CD80 variant immunomodulatory proteins and uses thereof

Variant CD80 polypeptides with modified IgV and IgC domains address the limitations of existing IS modulators by enhancing binding to CD28, PD-L1, or CTLA-4, providing effective immune response modulation for cancer and immunological diseases.

AU2023203586B2Pending Publication Date: 2026-07-23ALPINE IMMUNE SCIENCES INC
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Patent Information

Authority / Receiving Office
AU · AU
Patent Type
Applications
Current Assignee / Owner
ALPINE IMMUNE SCIENCES INC
Filing Date
2023-06-08
Publication Date
2026-07-23

AI Technical Summary

Technical Problem

Existing therapeutics for modulating the immunological synapse (IS) interactions between antigen-presenting cells and lymphocytes are inadequate, necessitating improved immunomodulatory proteins with altered binding specificity and affinity for CD28, PD-L1, or CTLA-4 to enhance immune response modulation.

Method used

Development of variant CD80 polypeptides with specific amino acid modifications in the IgV and IgC domains, including substitutions, insertions, or deletions, to alter binding affinity and specificity for CD28, PD-L1, or CTLA-4, providing enhanced immunomodulatory effects.

Benefits of technology

The variant CD80 polypeptides exhibit altered binding properties, offering improved immune response modulation and therapeutic potential in cancer and immunological diseases by enhancing interactions with CD28, PD-L1, or CTLA-4.

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Abstract

Provided herein are variant CD80 polypeptides, immunomodulatory proteins comprising variant CD80 polypeptides, and nucleic acids encoding such proteins. The immunomodulatory proteins provide therapeutic utility for a variety of immunological and oncological conditions. Compositions and methods for making and using such proteins are provided.
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Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a divisional application of Australian Patent Application No. 2017248830, the entire contents of which are incorporated herein by reference. INCORPORATION BY REFERENCE OF SEQUENCE LISTING

[0002] The present application is being fded along with a Sequence Listing in electronic format. The Sequence Listing is presented in ST.26 format and is based on the Sequence Listing filed for the parent application entitled "CD80 variant immunomodulatory proteins and uses thereof' FIELD

[0003] The present disclosure relates to therapeutic compositions for modulating immune response in the treatment of cancer and immunological diseases. In some aspects, the present disclosure relates to particular variants of CD80 that exhibit altered affinity for a cognate binding partner. BACKGROUND

[0004] Modulation of the immune response by intervening in the processes that occur in the immunological synapse (IS) formed by and between antigen-presenting cells (APCs) or target cells and lymphocytes is of increasing medical interest. Mechanistically, cell surface proteins in the IS can involve the coordinated and often simultaneous interaction of multiple protein targets with a single protein to which they bind. IS interactions occur in close association with the 2023203586 08 Jun 2023 junction of two cells, and a single protein in this structure can interact with both a protein on the same cell (cis) as well as a protein on the associated cell (trans), likely at the same time. Although therapeutics are known that can modulate the IS, improved therapeutics are needed. Provided are immunomodulatory proteins, including soluble proteins or transmembrane immunomodulatory proteins capable of being expressed on cells, that meet such needs. SUMMARY

[0005] In some embodiments, provided herein is a variant CD80 polypeptide containing an IgV domain or a specific binding fragment thereof, an IgC domain or a specific binding fragment thereof, or both, wherein the variant CD80 polypeptide containing one or more amino acid modifications in an unmodified CD80 or specific binding fragment thereof, corresponding to position(s) 4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 24, 25, 27, 28, 29, 30, 31, 33, 36, 37, 38, 40, 41, 42, 43, 44, 47, 48, 50, 52, 53, 54, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 74, 76, 77, 80, 81, 83, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 99, 102, 103, 104, 108, 107,109, 110, 114, 115, 116, 117, 118, 120, 121, 122, 126, 127, 128, 129, 130, 133, 137, 140, 142, 143, 144, 148, 149, 152, 154, 160, 162, 164, 168, 169, 174, 175, 177, 178, 183, 178, 185, 188, 190, 192, 193, or 199 with reference to numbering of SEQ ID NO: 28. In some embodiments, the one or more amino acid modifications includes one or more amino acid substitution, insertion or deletion. In some embodiments, the unmodified CD80 is a mammalian CD80 or a specific binding fragment thereof. In some embodiments, the unmodified CD80 is a human CD80 or a specific binding fragment thereof. In some embodiments, the variant CD80 polypeptide includes: the IgV domain or a specific binding fragment thereof; and the IgC domain or a specific binding fragment thereof. In some embodiments, the unmodified CD80 includes (i) the sequence of amino acids set forth in SEQ ID NO:28, (ii) a sequence of amino acids that has at least 95% sequence identity to SEQ ID NO:28; or (iii) is a portion thereof comprising an IgV domain or IgC domain or specific binding fragments thereof.

[0006] In some embodiments of any one of the variant CD80 polypeptides, the specific binding fragment of the IgV domain or the IgC domain has a length of at least 50, 60, 70, 80, 90, 100, 110 or more amino acids; the specific binding fragment of the IgV domain includes a length that is at least 80% of the length of the IgV domain set forth as amino acids 35-135 of SEQ ID NO:1; or the specific binding fragment of the IgC domain includes a length that is at least 80% of the length of the IgC domain set forth as amino acids 145-230 of SEQ ID NO:1. In some embodiments, the variant CD80 polypeptide contains up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 2 2023203586 08 Jun 2023 14, 15, 16, 17, 18, 19 or 20 amino acid modifications, optionally amino acid substitutions. In some embodiments, the variant CD80 polypeptide includes a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity to SEQ ID NO: 28, or a specific binding fragment thereof. In some embodiments, the variant CD80 exhibits altered binding specificity to the ectodomain of CD28, PD-L1, or CTLA-4 compared to the unmodified CD80. In some instances, the altered binding is altfered binding affinity and / or altered binding selectivity.

[0007] In some embodiments of any one of the variant CD80 polypeptides, the one or more amino acid substitution is V4M, K9E, E10R, VIIS, A12G, A12T, A12V, T13N, LI4A. S15V, S15F, C16S, C16G, C16L, G17W, H18L, H18R, H18Y, V20L, S21P, V22A, E24G, L25P, Q27R, T28A, T28S, R29C, R29D, R29H, R29V, I30V, Y31F, Y31H, Y31L, Q33H, K36E, K36G, K37E, K37Q, M38I, M38L, M38T, M38V, L40M, T41A, T41G, T41D, T41I, M42T, M43I, M43Q, M43R, M43V, S44P, M47T, N48I, N48D, W50G, E52G, Y53C, K54M, F59L, F59S, D60V, I61N, T62S, N63S, N64S, L65H, S66H, I67F, I67T, V68A, V68M, I69T, L70Q, L70P, L70R, L72P, P74L, D76G, E77G, E77K, Y80N, E81A, E81R, E81V, V83A, V83I, L85I, L85R, K86E, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90L, D90N, A91E, A91G, A91S, A91T, F92L, F92N, F92P, F92Y, K93I, K93E, K93Q, K93R, K93V, R94G, R94L, R94F, E95K, H96R, L97R, E99G, E99D, L102S, S103L, S103P, V104A, V104L, D107N, F108L, P109S, P109H, T110A, S114T, D115G, F116S, F116L, E117V, E117G, I118V, I118A, I118T, T120S, S121P, N122S, I126L, I126V,I127T, C128Y, C128R, S129L, S129P, T130A, G133D, P137L, S140T, L142S, E143G, N144S, N144D, L148S, N149D, N149S, N152T, T154I, T154A, E160G, E162G, Y164H, S168G, K169E, K169I, K169S, M174T, M174V, T175A, N177S, H178R, L183H, K185E, H188D, H188Q, R190S, N192D, Q193L, T199S, or a conservative amino acid substitution thereof.

[0008] In some embodiments, the variant CD80 polypeptide contains an IgV domain or an IgC domain, or a specific binding fragment thereof, comprising one or more amino acid deletions in an unmodified CD80 or specific binding fragment thereof. In some embodiments, the deletion corresponds to position 43 of SEQ ID NO: 28.

[0009] In some embodiments, the one or more amino acid substitution is V4M / L70Q / A91G / T120S / T130A, A12T / H18L / M43V / F59L / E77K / P109S / I118T, A12V / S15F / Y31H / T41G / T130A / P137L / N152T, V20L / L70Q / A91S / T120S / T130A, V22A / L70Q / S121P, E24G / L25P / L70Q / T120S, T28S / L70Q / A91G / E95K / T120S / T130A, 2023203586 08 Jun 2023 E24G / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / H96R, R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, R29H / E52G / L70R / E88G / A91G / T130A, R29H / E52G / T120S / T130A, R29V / Y31F / K36G / M38L / M43Q / E81R / V83VL85I / K89R / D90L / A91E / F92N / K93Q / R94G, R29V / M43Q / E81R / L85I / K89R / D90L / A91E / F92N / K93Q / R94G, Y31H / T41G / L70Q / A91G / T120S / T130A, K36G, K36G / K37Q / M38VL40M, K36G / K37Q / M38PF59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / E99G / T130A / N149S, K36E / I67T / L70Q / A91 G / T 120S / T130A / N152T, K37E / F59S / L70Q / A91 G / T 120S / T130A, M3 8T / L70Q / E77G / A91 G / T 120S / T130A / N152T, M38V / T41D / M43I / W50G / D76G / V83A / K89E / T120S / T130A, T41I / A91G, S44P / L70Q / A91 G / T 130A, E52G / L70Q / A91 G / T 120S / T130A, K54M / A91 G / T 120S, D60V / A91G / T120S / T130A, N63S / L70Q / A91G / T120S / T130A, S66H / D90G / T110A / F116L, I67F / L70R / E88G / A91G / T120S / T130A, I67T / L70Q / A91G / T120S, V68A / T110A, V68M / L70P / L72P / K86E, L70Q / A91G / T110A / T120S / T130A, L70Q / E81A / A91 G / T 120S / 1127T / T130A, L70Q / Y87N / A91 G / T 130A, L70Q / A91G, L70Q / A91G / E117G / T120S / T130A, L70Q / A91 G / T 120S / T130A, L70Q / A91 G / T 130A, L70Q / A91G / I118A / T20S / T130A, L70R / A91G / T120S / T130A, E88D / K89R / D90K / A91G / F92Y / K93R, K89E / T130A, K89R / D90K / A91G / F92Y / K93R, E8 8D / K89R / D90K / A91G / F92Y / K93R / N122S / N177S, K89R / D90K / A91G / F92Y / K93R / N122S / N177S, A91G, A91G / F92L / F108L / T120S, A91G / L102S, A91G / S103P, A91G / T120S / T130A, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 2023203586 08 Jun 2023 V / R94L / T120S / I127T / T130A, H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38ET41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / T130A / M174T, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / H188D, H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91 T / F92P / K93V / R94L / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / E143G / K169E / M174V / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L85R / K89N / A91T / F92P / K93V / R94L / T120 S / I127T / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / F108L / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / T120S / T130A / K169E / H18 8D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / I127T / C128Y / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 2023203586 08 Jun 2023 F / T130A / K169E, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / T120S / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A / L148S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / I61N / E81V / L85R / K89N / A91T / F92P / K93V / R94F / V104 A / T120S / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / F92P / K93V / R94F / I118 V / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / T62S / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / T130A / K169E / T175A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / F116S / T130A / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / L142S / H188D, C16S / H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T11OA / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / A91G / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / D76G / A91G / S103L / T120S / I127T / T 130A, Q33 deleted / Y53C / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E, T62S / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / S129L / H188D, K9E / E10R / V11S / A12G / T13N / K14A / S15V / C16L / G17W / H18Y / Y53C / L70Q / D90G / T130A / N149D / N152T / H188D, H18L / R29D / Y31L / Q33H / K36G / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / Il 18V / T120S / I127T / T130A / H188D, K89E / K93E / T130A, 2023203586 08 Jun 2023 S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / N48V V68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / P109H / I126L / K169I, H18L / R29D / Y31L / Q3 3H / K3 6G / M3 8 VT41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R, S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / D90 N / A91T / F92P / K93 V / R94L / T130A / N149S / E162G, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S / R190S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91 T / F92P / K93V / R94L / T130A / R190S, C16G / V22A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / D76G / E81V / L85R / K8 9N / A91T / F92P / K93V / R94L / I118T / T130A / S140T / N149S / K169VH178R / N192D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / E117V / I118T / N149S / S168G / H188Q, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / I118T / T130A / N149S / K169I, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / D115G / I118T / T130A / G133D / N149S, S129P, A91G / S129P, I69T / L70Q / A91G / T120S, Y31H / S129P, T28A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / V104L / T130A / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S / H188Q, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A / N149S / T154I, A12G / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 2023203586 08 Jun 2023 P / K93V / R94L / L97R / T130A / L183H, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / S140T / N149S / K169S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169VQ193L, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169I, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / T130A / N149S / K169I, I118T / C128R, Q27R / R29C / M42T / S129P / E160G, S129P / T154A, S21P / L70Q / D90G / T120S / T130A, L70Q / A91G / N144D, L70Q / A91G / I118A / T120S / T130A / K169E, V4M / L70Q / A91G / I118V / T120S / T130A / K169E, L70Q / A91G / 1118 V / T120S / T130A / K169E, L70Q / A91G / 1118V / T120S / T130A, V20L / L70Q / A91S / I118V / T120S / T130A, L70Q / A91G / E117G / I118V / T120S / T130A, A91G / 1118V / T 120S / T130A, L70R / A91G / 1118V / T 120S / T130A / T199S, L70Q / E81A / A91G / I118V / T120S / I127T / T130A, T28S / L70Q / A91G / E95K / I118V / T120S / I126V / T130A / K169E, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, K3 6E / I67T / L70Q / A91G / 1118 V / T 120S / T130A / N152T, E52G / L70Q / A91G / D107N / I118 V / T120S / T130A / K169E, K37E / F59S / L70Q / A91G / 1118 V / T 120S / T130A / K185E, D60V / A91G / 1118V / T 120S / T130AK169E, K54M / L70Q / A91G / Y164H / T120S, M3 8T / L70Q / E77G / A91G / 1118 V / T 120S / T130 A / N152T, Y31H / T41G / M43L / L70Q / A91G / I118V / T120S / I126V / T130A, L65H / D90G / T110A / F116L, R29H / E52G / D90N / I118V / T120S / T130A, I67T / L70Q / A91G / I118V / T120S, L70Q / A91G / T110A / I118V / T120S / T130A, M38V / T41D / M43VW50G / D76G / V83A / K89E / I118V / T120S / I126V / T130A, A12V / S15F / Y31H / M3 8L / T41G / M43L / D90N / T130A / P137L / N149D / N152T, I67F / L70R / E88G / A91G / I118V / T120S / T130A, E24G / L25P / L70Q / A91G / I118V / T120S / N152T, 2023203586 08 Jun 2023 A91G / F92L / F108L / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R / N122S / N177S, K36G / K37Q / M38PL40M / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / E99G / T130A / N14 9S, K36G / L40M, R29D / Y31L / Q33H / K36G / M38ET41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / T130A / K169E / M174T, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N48D / F59L / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / I118V / T120S / I127T / T130A / H188D, H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91 T / F92P / K93V / R94L / I118V / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / E143G / K169E / M174V / H188D, R29D / I30V / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L85R / K89N / A91T / F92P / K93V / R94L / I118 V / T120S / I127T / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / F108L / I118V / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / T130A / N149D / K169E / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 2023203586 08 Jun 2023 P / K93 V / R94L / I118 V / T120S / T130A / K169E / H18 8D, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / C128Y / T130A / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / E99D / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / I118 V / T 120S / T130A / K169E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / I61N / E81V / L85R / K89N / A91T / F92P / K93V / R94F / V104A / I118V / T120S / I126V / T130A, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / I118V / T120S / T130A, H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / L142S / H188D, C16S / H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T110A / I118V / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / A91G / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / D76G / A91G / S103L / I118V / T120S / I1 27T / T130A,Y53C / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / K169E, T62S / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E, Y53C / L70Q / D90G / T130A / N149D / N152T / H188D, H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / H188D, or H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S.

[0010] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide contains the IgV domain or a specific fragment thereof and / or the IgC domain or a specific fragment thereof. In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide contains the IgV domain or a specific binding fragment thereof. In some embodiments, the IgV domain or specific binding fragment thereof is the only CD80 portion of the variant CD80 polypeptide. In some embodiments, the IgC domain or specific binding fragment thereof is the only CD80 portion of the variant CD80 polypeptide. 2023203586 08 Jun 2023

[0011] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide includes the sequence of amino acids set forth in any of SEQ ID NOS: 55-108, 280346, 414-475 or a specific binding fragment thereof, or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to any of SEQ ID NOS: 55-108, 280-346, 414-475 or a specific binding fragment thereof and that contains the one or more of the amino acid substitutions. In some embodiments, the variant CD80 polypeptide includes the IgV domain or a specific binding fragment thereof. In some embodiments, the IgV domain or specific fragment thereof is the only CD80 portion of the variant CD80 polypeptide. In some embodiments, the IgC domain or specific fragment thereof is the only CD80 portion of the variant CD80 polypeptide. In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide includes the sequence of amino acids set forth in any of SEQ ID NOS: 153-195, 347, 373-386, 476-477 or a specific binding fragment thereof, a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to any of SEQ ID NOS: 153-195, 347, 373-386, 476-477 or a specific binding fragment thereof and that contains the one or more of the amino acid substitutions.

[0012] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28, PD-L1, or CTLA-4 with increased affinity compared to the unmodified CD80 polypeptide. In some of any such embodiments, the variant polypeptide specifically binds to the ectodomain of CD28, PD-L1 or CTLA-4 with increased selectivity compared to the binding of the unmodified CD80 for the ectodomain. In some aspects, the increased selectivity includes a greater ratio for one cognate binding partner selected from among CD28, PD-L1 and CTLA-4 versus another of the cognate binding partner compared to the ratio of binding of the unmodified CD80 polypeptide for the one cognate binding partner versus the another of the cognate binding partner.

[0013] In some embodiments, the variant polypeptide specifically binds to the ectodomain of CD28 with increased selectivity compared to the binding of the unmodified CD80 for the ectodomain of CD28. In some aspects, the increased selectivity includes a greater ratio for binding CD28 versus PD-L1 or CTLA-4 compared to the ratio of binding of the unmodified CD80 polypeptide for CD28 versus PD-L1 or CTLA-4. In some cases, the ratio is greater by at least or at least about 1.5-fold, 2.0-fold, 3.0-fold, 4.0-fold. 5-fold, 10-fold, 15-fold, 20-fold, 30fold, 40-fold, 50-fold or more. 2023203586 08 Jun 2023

[0014] In some embodiments, the variant CD80 polypeptide specifically binds to the ectodomain of CD28 with increased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the increased affinity to the ectodomain is increased more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, 20-fold, 30-fold, 40fold, 50-fold or 60-fold compared to the binding affinity of the unmodified CD80 for the ectodomain.

[0015] In some embodiments of any one of the variant CD80 polypeptides, the one or more amino acid substitutions corresponds to position(s) 12, 18, 20, 29, 31, 36, 40, 41, 43, 52, 59, 60, 63, 67, 70, 77, 81, 87, 88, 89, 90, 91, 92, 93, 107, 109, 114, 117, 118, 120, 122, 127, 130, 144, 169,177 or 199 with reference to numbering of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of A12T, H18L, V20L, R29H, Y31H, K36G, L40M, T41G, T41I, M43V, E52G, F59L, D60V, N63S, I67T, L70Q, L70R, E77K, E81A, Y87N, E88D, E88G, K89E, K89R, D90K, D90N, A91G, A91S, F92Y, K93R, D107N, P109S, S114T, E117G, I118A, Il 18T, I118V, T120S, I127T, T130A, N144D, K169E, N177S and T199S and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is A12T / H18L / M43V / F59L / E77K / P109S / I118T, V20L / L70Q / A91S / T120S / T130A, V20L / L70Q / A91S / 1118 V / T120S / T130A, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, T41VA91G, E52G / L70 / A91G / T120S / T130A, E52G / L70Q / A91G / D107N / I118V / T120S / T130A / K169E, D60V / A91G / T120S / T130A, D60V / A91G / 1118 V / T 120S / T130A / K169E, N63S / L70Q / A91G / T120S / T130A, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, L70Q / E81A / A91G / T120S / I127T / T130A, L70Q / E81A / A91G / I118V / T120S / I127T / T130A, L70Q / Y87N / A91G / T130A, L70Q / A91G, L70Q / A91G / N144D, L70Q / A91G / E117G / T120S / T130A, L70Q / A91G / E117G / I118V / T 120S / T130A, L70Q / A91G / I118A / T120S / T130A, L70Q / A91G / I118A / T120S / T130A / K169E, L70Q / A91 G / T 120S / T130A, L70Q / A91G / 1118V / T 120S / T130A / K169E, L70R / A91 G / T 120S / T130A, L70R / A91G / 1118V / T 120S / T130A / T199S, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R / N122S / N177S. 2023203586 08 Jun 2023

[0016] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of PD-L1 with increased affinity compared to the unmodified CD80 polypeptide. In some cases, the increased affinity to the ectodomain is increased more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, 20-fold, 30-fold, 40-fold, 50-fold or 60-fold compared to the binding affinity of the unmodified CD80 for the ectodomain. In some of any such embodiments, the variant polypeptide specifically binds to the ectodomain of PD-L1 with increased selectivity compared to the binding of the unmodified CD80 for the ectodomain. In some cases, the increased selectivity includes a greater ratio for binding PD-L1 versus CD28 or CTLA-4 compared to the ratio of binding of the unmodified CD80 polypeptide for PD-L1 versus CD28 or CTLA-4. In some instances, the ratio is greater by at least or at least about 1.5-fold, 2.0-fold, 3.0-fold, 4.0-fold. 5-fold, 10-fold, 15fold, 20-fold, 30-fold, 40-fold, 50-fold or more.

[0017] In some embodiments, the one or more amino acid substitutions corresponds to position(s) 12, 18, 29, 31, 33, 36, 38, 40, 41, 42, 43, 47, 59, 67, 70, 77, 81, 85, 87, 88, 89, 90, 91, 92, 93, 94, 109, 118, 120, 122, 144, 148, 149, or 177 with reference to numbering of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of A12T, H18L, R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, L40M, T41A, T41G, M42T, M43R, M43V, M47T, F59L, I67T, L70Q, E77K, E81V, L85R, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90N, A91G, A91T, F92P, F92Y, K93R, K93V, R94L, P109S, Il 18T, Il 18V, T120S, N122S, N144S, L148S, N149S, and N177S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is A12T / H18L / M43V / F59L / E77K / P109S / I118T, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, or A91G. 2023203586 08 Jun 2023

[0018] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28 and the ectodomain of PD-L1 with increased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions corresponds to position(s) 12, 18, 36, 40, 43, 59, 77, 88, 89, 90, 91, 92, 93, 109, 118, 122, 177 with reference to numbering of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of A12T, H18L, K36G, L40M, M43V, F59L, E77K, E88D, K89R, D90K, A91G, F92Y, K93R, P109S, I118T, N112S, N177S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is A12T / H18L / M43V / F59L / E77K / P109S / I118T, K36G, K36G / L40M, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R / N122S / N177S.

[0019] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CTLA-4 with increased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the increased affinity to the ectodomain is increased more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, 20-fold, 30-fold, 40-fold, 50-fold or 60-fold compared to the binding affinity of the unmodified CD80 for the ectodomain. In some of any such embodiments, the variant polypeptide specifically binds to the ectodomain of CTLA-4 with increased selectivity compared to the binding of the unmodified CD80 for the ectodomain. In some cases, the increased selectivity includes a greater ratio for binding CTLA-4 versus CD28 or PD-L1 compared to the ratio of binding of the unmodified CD80 polypeptide for CTLA-4 versus CD28 or PD-L1. In some embodiments, the ratio is greater by at least or at least about 1.5-fold, 2.0-fold, 3.0-fold, 4.0-fold. 5-fold, 10-fold, 15-fold, 20-fold, 30-fold, 40-fold, 50-fold or more.

[0020] In some embodiments, the one or more amino acid substitutions corresponds to position(s) 4, 29, 31, 36, 40, 41, 52, 67, 68, 70, 87, 88, 89, 90, 91, 92, 93, 107, 109, 110, 118, 120, 130, 144, or 169 with reference to numbering of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of V4M, R29H, Y31H, K36G, L40M, T41G, E52G, I67T, V68A, L70Q, Y87N, E88D, E88G, K89E, K89R, D90K, D90N, A91G, F92Y, K93R, D107N, P109S, T110A, Il 18V, T120S, T130A, N144D, and K169E and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is V4M / L70Q / A91G / T120S / T130A, 2023203586 08 Jun 2023 V4M / L70Q / A91G / 1118 V / T120S / T130A / K169E, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, E52G / L70Q / A91G / T120S / T130A, E52G / L70Q / A91G / D107N / I118V / T120S / T130A / K169E, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T12OS,V68A / T110A, L70Q / A91G, L70Q / A91G / N144D, L70Q / A91G / T120S / T130A, L70Q / A91G / I118V / T120S / T130A / K169E, L70Q / A91G / T130A, K89R / D90K / A91G / F92Y / K93R, E88D / K89R / D90K / A91G / F92Y / K93R, A91G / 1118 V / T 120S / T130A, or A91G / T120S / T130A.

[0021] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28 and the ectodomain of CTLA-4 with increased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions correspond(s) to position(s) 36, 40, 52, 70, 88, 89, 90, 91, 92, 93, 107, 118, 120, 130, 144, or 169 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of K36G, L40M, E52G, L70Q, E88D, K89R, D90K, A91G, F92Y, K93R, D107N, Il 18V, T120S, T130A, N144D, and K169E, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is K36G, K36G / L40M, E52G / L70Q / A91G / T120S / T130A, E52G / L70Q / A91G / D107N / I118V / T120S / T130A / K169E, L70Q / A91G, L70Q / A91G / N144D, L70Q / A91 G / T 120S / T130A, L70Q / A91G / 1118V / T 120S / T130A / K169E, E88D / K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R.

[0022] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of PD-L1 and the ectodomain of CTLA-4 with increased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions corresponds to position(s) 29, 31, 36, 40, 41, 67, 70, 87, 88, 89, 90, 91, 92, 93, 109, 118, 120, 122, or 178 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of R29H, Y31H, K36G, L40M, T41G, I67T, L70Q, Y87N, E88D, E88G, K89E, K89R, D90N, D90K, A91G, F92Y, K93R, P109S, Il 18V, T120S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R. 2023203586 08 Jun 2023

[0023] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28, the ectodomain of PD-L1, and the ectodomain of CTLA-4 with increased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions corresponds to position(s) 36, 40, 88, 89, 90, 91, 92, or 93 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of K36G, L40M, E88D, K89R, D90K, A91G, F92Y, K93R, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is K36G, K36G / L40M, E88D / K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R.

[0024] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28 or the ectodomain of PD-L1 with increased affinity compared to the unmodified CD80 polypeptide, and the variant CD80 polypeptide specifically binds to the ectodomain of CTLA-4 with decreased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions corresponds to position(s) 29, 31, 33, 36, 38, 41, 42, 43, 47, 63, 67, 70, 81, 85, 87, 88, 89, 90, 91, 92, 93, 94, 109, 114, 118, 120, 127, 130, 144, 148, or 149 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, T41A, T41G, M42T, M43R, M47T, N63S, I67T, L70Q, E81A, E81V, L85R, Y87N, E88G, K89E, K89N, D90N, A91G, A91T, F92P, K93V, R94L, P109S, S114T, Il 18T, Il 18V, T120S, I127T, T130A, N144S, L148S, and N149S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is N63S / L70Q / A91G / T120S / T130A, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, or L70Q / Y87N / A91G / T120S / I127T / T130A.

[0025] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28 with increased affinity compared to the unmodified CD80 polypeptide, and the variant CD80 polypeptide specifically binds to the ectodomain of CTLA-4 with decreased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions corresponds to position(s) 63, 70, 81, 87, 91, 114, 118, 120, 127, or 130 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of N63S, L70Q, E81A, Y87N, A91G, S114T, Il 18V, T120S, I127T, and T130A, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is 2023203586 08 Jun 2023 R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N 149S, R29H / Y31H / T41G / Y87N / E8 8G / K89E / D90N / A91G / P109S, N63S / L70Q / A91G / T120S / T130A, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, or L70Q / Y87N / A91G / T120S / I127T / T130A.

[0026] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of PD-L1 with increased affinity compared to the unmodified CD80 polypeptide, and the variant CD80 polypeptide specifically binds to the ectodomain of CTLA-4 with decreased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions corresponds to position(s) 29, 31, 33, 36, 38, 41, 42, 43, 47, 67, 70, 81, 85, 87, 88, 89, 90, 91, 92, 93, 94, 109, 118, 120, 144, 148, 149 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, T41A, T41G, M42T, M43R, M47T, I67T, L70Q, E81V, L85R, Y87N, E88G, K89E, K89N, D90N, A91G, A91T, F92P, K93V, R94L, P109S, I118T, Il 18V, T120S, N144S, L148S, andN149S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N 149S, R29H / Y31H / T41G / Y87N / E8 8G / K89E / D90N / A91 G / P 109S, I67T / L70Q / A91G / I118V / T120S, or I67T / L70Q / A91G / T120S. 2023203586 08 Jun 2023

[0027] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide specifically binds to the ectodomain of CD28 and the ectodomain of PD-L1 with increased affinity compared to the unmodified CD80 polypeptide, and the variant CD80 polypeptide specifically binds to the ectodomain of CTLA-4 with decreased affinity compared to the unmodified CD80 polypeptide. In some embodiments, the one or more amino acid substitutions correspond(s) to position(s) of 70, 81, 87, 91, or 120 of SEQ ID NO: 28. In some embodiments, the one or more amino acid substitution is selected from the group consisting of L70Q, Y87N, A91G, and T120S, and conservative amino acid substitutions thereof.

[0028] In some embodiments of any one of the variant CD80 polypeptides, the CD28 is a human CD28. In some embodiments, the PD-L1 is a human PD-L1. In some embodiments, the CTLA-4 is a human CTLA-4.

[0029] In some embodiments of any one of the variant CD80 polypeptides, the binding activity is altered (increased or decreased) more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, 20-fold, 30-fold 40-fold or 50-fold compared to the unmodified CD80 polypeptide.

[0030] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide is a soluble protein.

[0031] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide is linked to a multimerization domain. In some embodiments, the variant CD80 polypeptide is a multimeric polypeptide, optionally a dimeric polypeptide, comprising a first variant CD80 polypeptide linked to a multimerization domain and a second variant CD80 polypeptide linked to a multimerization domain. In some embodiments, the first variant CD80 polypeptide and the second variant CD80 polypeptide are the same or different. In some embodiments, the multimerization domain is an Fc domain or a variant thereof with reduced effector function.

[0032] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide is linked to a moiety that increases biological half-life of the polypeptide. In some embodiments, the variant CD80 polypeptide is linked to an Fc domain or a variant thereof with reduced effector function. In some embodiments, the Fc domain is mammalian, optionally human; or the variant Fc domain contains one or more amino acid modifications compared to an unmodified Fc domain that is mammalian, optionally human. In some embodiments, the Fc domain or variant thereof contains the sequence of amino acids set forth in SEQ ID NO:226 or 2023203586 08 Jun 2023 SEQ ID NO:227 or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to SEQ ID NO:226 or SEQ ID NO:227. In some embodiments, the variant CD80 polypeptide is linked indirectly via a linker.

[0033] In some embodiments of any one of the variant CD80 polypeptides that is a transmembrane immunomodulatory protein, the variant CD80 polypeptide further contains a transmembrane domain linked to the extracellular domain (ECD) or specific binding fragment thereof of the variant CD80 polypeptide. In some embodiments, the transmembrane domain contains the sequence of amino acids set forth as residues 243-263 of SEQ ID NO: 1 or a functional variant thereof that exhibits at least 85% sequence identity to residues 243-263 of SEQ ID NO: 1. In some embodiments, the variant CD80 polypeptide further contains a cytoplasmic signaling domain linked to the transmembrane domain. In some embodiments, the cytoplasmic signaling domain contains the sequence of amino acids set forth as residues 264-288 of SEQ ID NO: 1 or a functional variant thereof that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to residues 264-288 of SEQ ID NO: 1.

[0034] In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 increases IFN-gamma (interferon-gamma) expression relative to the unmodified CD80 in an in vitro primary T-cell assay. In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 decreases IFN-gamma (interferon-gamma) expression relative to the unmodified CD80 in an in vitro primary T-cell assay. In some embodiments of any one of the variant CD80 polypeptides, the variant CD80 polypeptide is deglycosylated.

[0035] In some embodiments, provided herein is an immunomodulatory polypeptide comprising the variant CD80 according to any one of the embodiments described herein linked to a second polypeptide comprising an immunoglobulin superfamily (IgSF) domain. In some embodiments, the IgSF domain is affinity modified and exhibits altered binding to one or more of its cognate binding partner(s) compared to the unmodified or wild-type IgSF domain. In some embodiments, the IgSF domain exhibits increased binding to one or more of its cognate binding partner(s) compared to the unmodified or wild-type IgSF domain. In some embodiments, the variant CD80 is a first variant CD80 and the IgSF domain of the second polypeptide is an IgSF domain from a second variant CD80 according to any one of the embodiments described herein, wherein the first and second variant CD80 are the same or different. In some embodiments, the 2023203586 08 Jun 2023 variant CD80 polypeptide is capable of specifically binding to CD28, PD-L1, or CTLA-4, and the IgSF domain of the second polypeptide is capable of binding to a cognate binding partner other than one specifically bound by the variant CD80 polypeptide. In some embodiments, the variant CD80 polypeptide is capable of specifically binding to CD28 or PD-L1, and the IgSF domain is capable of binding to a cognate binding partner other than one specifically bound by the variant CD80 polypeptide. In some embodiments, the variant CD80 polypeptide is capable of specifically binding to CD28 or CTLA-4, and the IgSF domain is capable of binding to a cognate binding partner other than one specifically bound by the variant CD80 polypeptide. In some embodiments, the variant CD80 polypeptide is capable of specifically binding to CTLA-4 or PD-L1 and the IgSF domain is capable of binding to a cognate binding partner other than one specifically bound by the variant CD80 polypeptide. In some embodiments, the IgSF domain is from a member of the B7 family. In some embodiments, the IgSF domain is a tumor-localizing moiety that binds to a ligand expressed on a tumor. In some embodiments, the ligand is B7H6. In some embodiments, the IgSF domain is from NKp30. In some embodiments, the IgSF domain is affinity modified and exhibits increased binding to one or more of its cognate binding partner(s) compared to the unmodified or wild-type IgSF domain. In some embodiments, the IgSF domain is or contains an IgV domain. In some embodiments, the variant CD80 polypeptide is or contains an IgV domain.

[0036] In some embodiments according to any one of the immunomodulatory proteins, the immunomodulatory protein contains a multimerization domain linked to one or both of the variant CD80 polypeptide and the second polypeptide comprising the IgSF domain. In some embodiments, the multimerization domain is an Fc domain or a variant thereof with reduced effector function. In some embodiments, the immunomodulatory protein is dimeric. In some embodiments, the immunomodulatory protein is homodimeric. In some cases, the immunomodulatory protein is heterodimeric.

[0037] In some embodiments, provided herein is a conjugate comprising a variant CD80 according to any one of the embodiments described herein or an immunomodulatory polypeptide according to any one of the embodiments described herein linked to a moiety. In some embodiments, the moiety is a targeting moiety that specifically binds to a molecule on the surface of a cell. In some embodiments, the targeting moiety specifically binds to a molecule on the surface of an immune cell. In some embodiments, the immune cell is an antigen presenting cell or a lymphocyte. In some embodiments, the targeting moiety is a tumor-localizing moiety that 2023203586 08 Jun 2023 binds to a molecule on the surface of a tumor. In some embodiments, the moiety is a protein, a peptide, nucleic acid, small molecule or nanoparticle. In some embodiments, the moiety is an antibody or antigen-binding fragment. In some of any such embodiments, the conjugate is divalent, tetravalent, hexavalent or octavalent.

[0038] In some embodiments, provided herein is a nucleic acid molecule encoding a variant CD80 according to any one of the embodiments described herein or an immunomodulatory polypeptide according to any one of the embodiments described herein. In some embodiments, the nucleic acid molecule is a synthetic nucleic acid. In some embodiments, the nucleic acid is cDNA.

[0039] In some embodiments, provided herein is a vector comprising the nucleic acid of any one of the embodiments described herein. In some embodiments, the vector is an expression vector.

[0040] In some embodiments, the vector is a mammalian vector or a viral vector.

[0041] In some embodiments, provided herein is a cell comprising the vector according to any one of the embodiments described herein. In some embodiments, the cell is a mammalian cell. In some embodiments, the cell is a human cell.

[0042] In some embodiments, provided herein is a method of producing a variant CD80 polypeptide or an immunomodulatory protein, comprising introducing the nucleic acid molecule according to any one of the embodiments described herein or vector according to any one of the embodiments described herein into a host cell under conditions to express the protein in the cell. In some embodiments, the method further includes isolating or purifying the variant CD80 polypeptide or immunomodulatory protein from the cell.

[0043] In some embodiments, provided herein is a method of engineering a cell expressing a variant CD80 polypeptide, comprising introducing a nucleic acid molecule encoding the variant CD80 polypeptide according to any one of the embodiments described herein into a host cell under conditions in which the polypeptide is expressed in the cell.

[0044] In some embodiments, provided herein is an engineered cell, expressing the variant CD80 polypeptide according to any one of the embodiments described herein, the immunomodulatory protein according to any one of the embodiments described herein, the nucleic acid molecule according to any one of the embodiments described herein, or the vector according to any one of the embodiments described herein. In some embodiments, the variant CD80 polypeptide or immunomodulatory polypeptide contains a signal peptide. In some aspects, 2023203586 08 Jun 2023 the variant CD80 polypeptide or immunomodulatory polypeptide does not contain a transmembrane domain and / or is not expressed on the surface of the cell. In some embodiments, the variant CD80 polypeptide or immunomodulatory polypeptide is secreted from the engineered cell.

[0045] In some embodiments, the engineered cell contains a variant CD80 polypeptide that contains a transmembrane domain and / or is the transmembrane immunomodulatory protein according to any one of the embodiments described herein. In some embodiments, the variant CD80 polypeptide is expressed on the surface of the cell.

[0046] In some embodiments, the engineered cell is an immune cell. In some embodiments, the immune cell is an antigen presenting cell (APC) or a lymphocyte. In some embodiments, the engineered cell is a primary cell. In some embodiments, the engineered cell is a mammalian cell. In some embodiments, the engineered cell is a human cell. In some embodiments, the lymphocyte is a T cell. In some embodiments, the APC is an artificial APC.

[0047] In some of any such embodiments, the engineered cell further contains a chimeric antigen receptor (CAR) or an engineered T-cell receptor.

[0048] Also provided is an infectious agent, comprising a nucleic acid molecule encoding a variant CD80 polypeptide according to any one of the embodiments described herein or an immunomodulatory polypeptide according to any one of the embodiments described herein. In some instances, the encoded variant CD80 polypeptide or immunomodulatory polypeptide does not contain a transmembrane domain and / or is not expressed on the surface of a cell in which it is expressed. In some embodiments, the encoded variant CD80 polypeptide or immunomodulatory polypeptide is secreted from a cell in which it is expressed. In some aspects, the encoded variant CD80 polypeptide contains a transmembrane domain. In some aspects, the encoded variant CD80 polypeptide is expressed on the surface of a cell in which it is expressed.

[0049] In some of any such embodiments, the infectious agent is a bacterium or a virus. In some cases, the virus is an oncolytic virus. In some embodiments, the oncolytic virus is an adenoviruses, adeno-associated viruses, herpes viruses, Herpes Simplex Virus, Vesticular Stomatic virus, Reovirus, Newcastle Disease virus, parvovirus, measles virus, vesticular stomatitis virus (VSV), Coxsackie virus or a Vaccinia virus. In some embodiments, the virus specifically targets dendritic cells (DCs) and / or is dendritic cell-tropic. In some instances, the virus is a lentiviral vector that is pseudotyped with a modified Sindbis virus envelope product. 2023203586 08 Jun 2023

[0050] In some of any such embodiments, the infectious agent further contains a nucleic acid molecule encoding a further gene product that results in death of a target cell or that can augment or boost an immune response. In some embodiments, the further gene product is selected from an anticancer agent, anti-metastatic agent, an antiangiogenic agent, an immunomodulatory molecule, an immune checkpoint inhibitor, an antibody, a cytokine, a growth factor, an antigen, a cytotoxic gene product, a pro-apoptotic gene product, an anti-apoptotic gene product, a cell matrix degradative gene, genes for tissue regeneration or a reprogramming human somatic cells to pluripotency.

[0051] In some embodiments, provided herein is a pharmaceutical composition, comprising the variant CD80 polypeptide according to any one of the embodiments described herein, an immunomodulatory protein according to any one of the embodiments described herein, a conjugate according to any one of the embodiments described herein, or an engineered cell according to any one of the embodiments described herein. In some embodiments, the pharmaceutical composition further includes a pharmaceutically acceptable excipient. In some embodiments, the pharmaceutical composition is sterile.

[0052] In some embodiments, provided herein is an article of manufacture comprising the pharmaceutical composition according to any one of the embodiments described herein in a vial. In some embodiments, the vial is sealed.

[0053] In some embodiments, provided herein is a kit comprising the pharmaceutical composition according to any one of the embodiments described herein and instructions for use. In some embodiments, provided herein is a kit comprising the article of manufacture according to any one of the embodiments described herein and instructions for use.

[0054] In some embodiments, provided herein is a method of modulating an immune response in a subject, comprising administering the pharmaceutical composition according to any one of the embodiments described herein to the subject. In some embodiments, the method includes administering the engineered cells according to any one of the embodiments described herein. In some embodiments, the engineered cells are autologous to the subject. In some embodiments, the engineered cells are allogenic to the subject

[0055] In some embodiments, modulating the immune response treats a disease or condition in the subject. In some embodiments, the immune response is increased. In some embodiments, an immunomodulatory protein or conjugate comprising a variant CD80 polypeptide linked to a tumor-localizing moiety is administered to the subject. In some cases, the tumor-localizing 2023203586 08 Jun 2023 moiety is or contains a binding molecule that recognizes a tumor antigen. In some instances, the binding molecule contains an antibody or an antigen-binding fragment thereof or contains a wildtype IgSF domain or variant thereof.

[0056] In some embodiments, a pharmaceutical composition comprising the immunomodulatory protein according to any one of the embodiments described herein or the conjugate according to any one of the embodiments described herein is administered to the subject. In some embodiments, an engineered cell comprising a variant CD80 polypeptide that is a transmembrane immunomodulatory protein is administered to the subject and / or the engineered cell according to any one of the embodiments described herein is administered to the subject.

[0057] In some embodiments, an infectious agent encoding a variant CD80 polypeptide that is a transmembrane immunomodulatory protein is administered to the subject, optionally under conditions in which the infectious agent infects a tumor cell or immune cell and the transmembrane immunomodulatory protein is expressed on the surface of the infected cell. In some aspects, the transmembrane immunomodulatory protein is a transmembrane immunomodulatory protein according to any one of the embodiments described herein.

[0058] In some embodiments, the disease or condition is a tumor or cancer. In some embodiments, the disease or condition is selected from melanoma, lung cancer, bladder cancer, hematological malignancy, liver cancer, brain cancer, renal cancer, breast cancer, pancreatic cancer, colorectal cancer, spleen cancer, prostate cancer, testicular cancer, ovarian cancer, uterine cancer, gastric carcinoma, a musculoskeletal cancer, a head and neck cancer, a gastrointestinal cancer, a germ cell cancer, or an endocrine and neuroendocrine cancer.

[0059] In some embodiments, the immune response is decreased by the provided methods of modulating the immune response.

[0060] In some embodiments, a variant CD80 polypeptide or immunomodulatory protein that is soluble is administered to the subject. In some cases, the soluble polypeptide or immunomodulatory protein is an Fc fusion protein. In some of any such embodiments, a pharmaceutical composition comprising a variant CD80 polypeptide according to any one of the embodiments described herein, or the immunomodulatory protein according to any one of the embodiments described herein is administered to the subject. In some embodiments, an engineered cell comprising a secretable variant CD80 polypeptide is administered to the subject. 2023203586 08 Jun 2023 In some embodiments, an engineered cell according to any one of the embodiments described herein is administered to the subject.

[0061] In some embodiments, an infectious agent encoding a variant CD80 polypeptide that is a secretable immunomodulatory protein is administered to the subject, optionally under conditions in which the infectious agent infects a tumor cell or immune cell and the secretable immunomodulatory protein is secreted from the infected cell.

[0062] In some of any such embodiments, the disease or condition is an inflammatory or autoimmune disease or condition. In some embodiments, the disease or condition is an Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, a vasculitis, an autoimmune skin disease, transplantation, a Rheumatic disease, an inflammatory gastrointestinal disease, an inflammatory eye disease, an inflammatory neurological disease, an inflammatory pulmonary disease, an inflammatory endocrine disease, or an autoimmune hematological disease. In some embodiments, the disease or condition is selected from inflammatory bowel disease, transplant, Crohn's disease, ulcerative colitis, multiple sclerosis, asthma, rheumatoid arthritis, or psoriasis. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG. 1A-1C depicts various formats of the provided variant IgSF domain molecules. FIG. 1A depicts soluble molecules, including : (1) a variant IgSF domain (vlgD), e.g. variant CD80, fused to an Fc chain; (2) a stack molecule containing a first variant IgSF domain (first vlgD), e.g. variant CD80, and a second IgSF domain, such as a second variant IgSF domain (second vlgD); (3) a tumor targeting IgSF molecule containing a first variant IgSF domain (vlgD), e.g. variant CD80, and an IgSF domain that targets to a tumor antigen, such as an NkP30 IgSF domain; and (4) a variant IgSF domain (vlgD), e.g. variant CD80, linked to an antibody (V-Mab). FIG. IB depicts a transmembrane immunomodulatory protein (TIP) containing a variant IgSF domain (vlgD) expressed on the surface of a cell. In an exemplary embodiment, the cognate binding partner of the transmembrane bound vlgD is a costimulatory receptor, and the TIP containing the vlgD (e.g. CD80 vlgD) agonizes the costimulatory receptor such that the TIP induces a positive signal in the cell expressing the costimulatory receptor. FIG. IC depicts a secreted immunomodulatory protein (SIP) in which a variant IgSF domain (vlgD) is secreted from a cell, such as a first T cell (e.g. CAR T cell). In an exemplary embodiment, the cognate binding partner of the secreted vlgD is an activating receptor, e.g. CD28, which can be expressed 2023203586 08 Jun 2023 on the first cell (e.g. T cell) and / or on a second cell (e.g. T cell; either endogenous or engineered, such as a CAR T cell). Upon binding of the SIP with its cognate binding partner, signaling via the activating receptor is blocked. In all cases, the vlgD can be a V-domain (IgV) only, the combination of the V-domain (IgV) and C-domain (IgC), including the entire extracellular domain (ECD), or any combination of Ig domains of the IgSF superfamily member.

[0064] FIG. 2 depicts an exemplary schematic of the activity of a variant IgSF domain (vlgD) fused to an Fc (vlgD-Fc) in which the vlgD is a variant of an IgSF domain of CD80. As shown, a soluble vlgD of CD80 interacts with its cognate binding partners to block interactions of CD28, respectively, thereby blocking costimulation by the CD28 costimulatory receptors.

[0065] FIG. 3 depicts an exemplary schematic of a stack molecule for localizing the variant IgSF domain (vlgD) to a tumor cell. In this format, the stack molecule contains a first variant IgSF domain (first vlgD) and a second IgSF domain (e.g. a second vlgD) in which the second IgSF domain (e.g a second vlgD) is a tumor-targeted IgSF domain that binds to a tumor antigen. An exemplary tumor-targeted IgSF domain is an IgSF domain of NkP30, which binds to the tumor antigen B7-H6. In this depiction, the vlgD is a variant of an IgSF domain of CD80. As shown, binding of tumor-targeted IgSF domain to the surface of the tumor cell localizes the first vlgD on the tumor cell surface where it can interact with one or more of its cognate binding partner (e.g. CD28) expressed on the surface of an adjacent immune cell (e.g. T cell) to stimulate the costimulatory receptor.

[0066] FIG. 4 depicts various exemplary configurations of a stack molecule containing a first variant IgSF domain (first vlgD) and a second IgSF domain, such as a second variant IgSF domain (second vlgD). As shown, the first vlgD and second IgSF domain are independently linked, directly or indirectly, to the N- or C-terminus of an Fc subunit. For generating a homodimeric Fc molecule, the Fc subunit is one that is capable of forming a homodimer with a matched Fc subunit by co-expression of the individual Fc subunits in a cell. For generating a heterodimeric Fc molecule, the individual Fc subunits contain mutations (e.g. “knob-into-hole” mutations in the CH3 domain), such that formation of the heterodimer is favored compared to homodimers when the individual Fc subunits are co-expressed in a cell.

[0067] FIG. 5 depicts an exemplary schematic of the activity of a variant IgSF domain (vlgD) conjugated to an antibody (V-Mab) in which the antibody (e.g. anti-HER2 antibody) binds to an antigen on the surface of the tumor cell. In this depiction, the vlgD is a variant of an IgSF domain of CD80. As shown, binding of the antibody to the surface of the tumor cell 2023203586 08 Jun 2023 localizes the vlgD on the tumor cell surface where it can interact with one or more of its cognate binding partners expressed on the surface of an adjacent immune cell (e.g. T cell) to agonize receptor signaling. In an exemplary embodiment as shown, the variant IgSF domain (vlgD) is a variant of an IgSF domain of CD80. Binding of the CD80 vlgD to CD28 costimulatory receptors provides an agonist or costimulatory signal.

[0068] FIG. 6A-6C depicts various exemplary configurations of a variant IgSF domain (vlgD) conjugated to an antibody (V-Mab). FIG. 6A shows various configurations in which a vlgD is linked, directly or indirectly, to the N- and / or C-terminus of the light chain of an antibody. FIG. 6B shows various configurations in which a vlgD is linked, directly or indirectly, to the N- and / or C-terminus of the heavy chain of an antibody. FIG. 6C depicts the resulting V-Mab configurations when a light chain of FIG. 6A and a heavy chain of FIG. 6B are co-expressed in a cell.

[0069] FIG. 7A depicts results of a competition binding assay for binding of biotinylated recombinant CD28 Fc fusion protein (rCD28.Fc) to immobilized variant CD80 A91G ECD-Fc fusion molecule in the presence of unlabeled recombinant human PD-Ll-his, human CTLA-4-his or human-PD-L2-Fc fusion protein.

[0070] FIG. 7B depicts results of a competition binding assay for binding of biotinylated recombinant human PD-Ll-his monomeric protein to immobilized variant CD80 A91G ECD-Fc fusion molecule in the presence of unlabeled recombinant human rCD28.Fc, human CTLA-4.Fc or human PD-L2.Fc.

[0071] FIG. 8 depicts impedance results reflecting cytotoxic killing activity of cells engineered with an anti-CD19 chimeric antigen receptor (CAR) alone or with an exemplary transmembrane immunomodulatory TIP (CD80-TIP or ICOSL-TIP) or the corresponding CD80 or ICOSL wild-type transmembrane protein following co-culture with target antigen-expressing cells. Impedance was assessed using the Acea Real-Time Cell Analyzer (RTCA), which measures the impedance variations in the culture media of a 96-well microelectronic plate (Eplate). DETAILED DESCRIPTION

[0072] Provided herein are immunomodulatory proteins that are or comprise variants or mutants of CD80 and specific binding fragments thereof that exhibit altered binding activity or affinity to at least one target ligand cognate binding partner (also called counter-structure ligand protein). In some embodiments, the variant CD80 polypeptides contain one or more amino acid 27 2023203586 08 Jun 2023 modifications (e.g., amino acid substitutions, deletions, or additions) compared to an unmodified or wild-type CD80 polypeptide. In some embodiments, the variant CD80 polypeptides contain one or more amino acid modifications (e.g., substitutions) compared to an unmodified or wildtype CD80 polypeptide. In some embodiments, the one or more amino acid modifications (e.g., substitutions) are in an IgSF domain (e.g. IgV) of an unmodified or wild-type CD80 polypeptide. In some embodiments, the altered binding activity or affinity, such as increased or decreased binding activity or affinity, is for at least one of the cognate binding partner proteins CD28, PD-Ll, or CTLA-4. In some embodiments, the variant CD80 polypeptides exhibit altered, such as increased or decreased, binding activity or affinity to one or more of CD28, PD-L1, or CTLA-4 compared to the unmodified or wild-type CD80 not containing the one or more modifications. In some embodiments, the immunomodulatory proteins are soluble. In some embodiments, the immunomodulatory proteins are transmembrane immunomodulatory proteins capable of being expressed on the surface of cells. In some embodiments, also provided herein are one or more other immunomodulatory proteins that are conjugates or fusions containing a variant CD80 polypeptide provided herein and one or more other moiety or polypeptide.

[0073] In some embodiments, the variant CD80 polypeptides exhibit increased binding affinity to one or more of CD28, PD-L1, or CTLA-4 compared to the unmodified or wild-type CD80 not containing the one or more modifications. In some embodiments, the variant CD80 polypeptides exhibit decreased binding affinity to one or more of CD28, PD-L1, or CTLA-4 compared to the unmodified or wild-type CD80 not containing the one or more modifications. In some embodiments, the variant CD80 polypeptides exhibit increased binding affinity to one or more of CD28, PD-L1, or CTLA-4, and decreased binding affinity to another one or more of CD28, PD-L1, or CTLA-4 compared to the unmodified or wild-type CD80 not containing the one or more modifications.

[0074] In some embodiments, also provided herein are one or more other immunomodulatory proteins that are conjugates or fusions containing a variant CD80 polypeptide provided herein and one or more other moiety or polypeptide. In some embodiments, the variant CD80 polypeptides and immunomodulatory proteins modulate an immunological immune response, such an increase or decrease an immune response. In some embodiments, the variant CD80 polypeptides and immunomodulatory proteins provided herein can be used for the treatment of diseases or conditions that are associated with a dysregulated immune response. 2023203586 08 Jun 2023

[0075] In some embodiments, the provided variant CD80 polypeptides modulate T cell activation via interactions with costimulatory signaling molecules. In general, antigen specific T-cell activation generally requires two distinct signals. The first signal is provided by the interaction of the T-cell receptor (TCR) with major histocompatibility complex (MHC) associated antigens present on antigen presenting cells (APCs). The second signal is costimulatory to TCR engagement and necessary to avoid T-cell apoptosis or anergy.

[0076] In some embodiments, under normal physiological conditions, the T cell-mediated immune response is initiated by antigen recognition by the T cell receptor (TCR) and is regulated by a balance of co-stimulatory and inhibitory signals (e.g., immune checkpoint proteins). The immune system relies on immune checkpoints to prevent autoimmunity (i.e., self- tolerance) and to protect tissues from excessive damage during an immune response, for example during an attack against a pathogenic infection. In some cases, however, these immunomodulatory proteins can be dysregulated in diseases and conditions, including tumors, as a mechanism for evading the immune system.

[0077] In some embodiments, among known T-cell costimulatory receptors is CD28, which is the T-cell costimulatory receptor for the ligands B7-1 (CD80) and B7-2 (CD86) both of which are present on APCs. These same ligands can also bind to the inhibitory T-cell receptor CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) with greater affinity than for CD28; the binding to CTLA-4 acts to down-modulate the immune response. Likewise, CD80 is able to bind to programmed death ligand 1 (PD-L1). PD-L1 also is a negative regulator of immune activation and is capable of down-modulating the immune response via interactions with programmed death 1 (PD-1) receptor. The binding of CD80 to PD-L1 can block the interaction between PD-L1 and PD-1, and thereby potentiate or enhance the immune response. Thus, in some cases, interactions of CD80 with CD28 and PD-L1 yield overlapping and complementary effects.

[0078] In some embodiments, CD28 and PD-L1 may play complementary roles in modulating an immune response. Enhancement or suppression of the activity of these receptors has clinical significance for treatment of inflammatory and autoimmune disorders, cancer, and viral infections. In some cases, however, therapies to intervene and alter the costimulatory effects of both receptors are constrained by the spatial orientation requirements as well as size limitations imposed by the confines of the immunological synapse. In some aspects, existing therapeutic drugs, including antibody drugs, may not be able to interact simultaneously with the multiple target proteins involved in modulating these interactions. In addition, in some cases, 2023203586 08 Jun 2023 existing therapeutic drugs may only have the ability to antagonize, but not agonize, an immune response. Additionally, pharmacokinetic differences between drugs that independently target one or the other of these two receptors can create difficulties in properly maintaining a desired blood concentration of such drug combinations throughout the course of treatment.

[0079] In some embodiments, the provided variant CD80 polypeptides or immunomodulatory proteins modulate (e.g. increase or decrease) immunological activity induced or associated with costimulatory receptors CD28 or PD-L1 and, in some cases, CTLA-4. Thus, in some embodiments, the provided polypeptides overcome these constraints by providing variants CD80 with independent binding affinities to both CD28 and PD-L1, and, in some cases, CTLA-4, thereby agonizing or antagonizing the complementary effects of costimulation by receptors. Methods of making and using these variants of CD80 are also provided.

[0080] All publications, including patents, patent applications scientific articles and databases, mentioned in this specification are herein incorporated by reference in their entirety for all purposes to the same extent as if each individual publication, including patent, patent application, scientific article or database, were specifically and individually indicated to be incorporated by reference. If a definition set forth herein is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications and other publications that are herein incorporated by reference, the definition set forth herein prevails over the definition that is incorporated herein by reference.

[0081] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. I. DEFINITIONS

[0082] Unless defined otherwise, all terms of art, notations and other technical and scientific terms or terminology used herein are intended to have the same meaning as is commonly understood by one of ordinary skill in the art to which the claimed subject matter pertains. In some cases, terms with commonly understood meanings are defined herein for clarity and / or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art.

[0083] The terms used throughout this specification are defined as follows unless otherwise limited in specific instances. As used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms, acronyms, and abbreviations used 30 2023203586 08 Jun 2023 herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Unless indicated otherwise, abbreviations and symbols for chemical and biochemical names is per IUPAC-IUB nomenclature. Unless indicated otherwise, all numerical ranges are inclusive of the values defining the range as well as all integer values inbetween.

[0084] The term “affinity modified” as used in the context of an immunoglobulin superfamily domain, means a mammalian immunoglobulin superfamily (IgSF) domain having an altered amino acid sequence (relative to the corresponding wild-type parental or unmodified IgSF domain) such that it has an increased or decreased binding affinity or avidity to at least one of its cognate binding partners (alternatively “counter-structures”) compared to the parental wild-type or unmodified (i.e., non-affinity modified) IgSF control domain. Included in this context is an affinity modified CD80 IgSF domain. In some embodiments, the affinity-modified IgSF domain can contain 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or more amino acid differences, such as amino acid substitutions, in a wildtype or unmodified IgSF domain. An increase or decrease in binding affinity or avidity can be determined using well known binding assays such as flow cytometry. Larsen et al., American Journal of Transplantation, Vol 5: 443-453 (2005). See also, Linsley et al., Immunity, 1: 7930801 (1994). An increase in a protein’s binding affinity or avidity to its cognate binding partner(s) is to a value at least 10% greater than that of the wild-type IgSF domain control and in some embodiments, at least 20%, 30%, 40%, 50%, 100%, 200%, 300%, 500%, 1000%, 5000%, or 10000% greater than that of the wild-type IgSF domain control value. A decrease in a protein’s binding affinity or avidity to at least one of its cognate binding partner is to a value no greater than 90% of the control but no less than 10% of the wild-type IgSF domain control value, and in some embodiments no greater than 80%, 70% 60%, 50%, 40%, 30%, or 20% but no less than 10% of the wild-type IgSF domain control value. An affinity-modified protein is altered in primary amino acid sequence by substitution, addition, or deletion of amino acid residues. The term “affinity modified IgSF domain” is not be construed as imposing any condition for any particular starting composition or method by which the affinity-modified IgSF domain was created. Thus, the affinity modified IgSF domains of the present invention are not limited to wild type IgF domains that are then transformed to an affinity modified IgSF domain by any particular process of affinity modification. An affinity modified IgSF domain polypeptide can, for example, be generated starting from wild type mammalian IgSF domain sequence information, 2023203586 08 Jun 2023 then modeled in silico for binding to its cognate binding partner, and finally recombinantly or chemically synthesized to yield the affinity modified IgSF domain composition of matter. In but one alternative example, an affinity modified IgSF domain can be created by site-directed mutagenesis of a wild-type IgSF domain. Thus, affinity modified IgSF domain denotes a product and not necessarily a product produced by any given process. A variety of techniques including recombinant methods, chemical synthesis, or combinations thereof, may be employed.

[0085] The term “allogeneic” as used herein means a cell or tissue that is removed from one organism and then infused or adoptively transferred into a genetically dissimilar organism of the same species. In some embodiments of the invention, the species is murine or human.

[0086] The term “autologous” as used herein means a cell or tissue that is removed from the same organism to which it is later infused or adoptively transferred. An autologous cell or tissue can be altered by, for example, recombinant DNA methodologies, such that it is no longer genetically identical to the native cell or native tissue which is removed from the organism. For example, a native autologous T-cell can be genetically engineered by recombinant DNA techniques to become an autologous engineered cell expressing a transmembrane immunomodulatory protein and / or chimeric antigen receptor (CAR), which in some cases involves engineering a T-cell or TIL (tumor infiltrating lymphocyte). The engineered cells are then infused into a patient from which the native T-cell was isolated. In some embodiments, the organism is human or murine.

[0087] The terms “binding affinity,” and “binding avidity” as used herein means the specific binding affinity and specific binding avidity, respectively, of a protein for its counter-structure under specific binding conditions. In biochemical kinetics avidity refers to the accumulated strength of multiple affinities of individual non-covalent binding interactions, such as between CD80 and its counter-structures PD-L1, CD28, and / or CTLA-4. As such, avidity is distinct from affinity, which describes the strength of a single interaction. An increase or attenuation in binding affinity of a variant CD80 containing an affinity modified CD80 IgSF domain to its counter-structure is determined relative to the binding affinity of the unmodified CD80, such as an unmodified CD80 containing the native or wild-type IgSF domain, such as IgV domain. Methods for determining binding affinity or avidity are known in art. See, for example, Larsen et al., American Journal of Transplantation, Vol 5: 443-453 (2005). In some embodiments, a variant CD80, such as containing an affinity modified IgSF domain, specifically binds to CD28, PD-L1 and / or CTLA-4 measured by flow cytometry with a binding affinity that yields a Mean 2023203586 08 Jun 2023 Fluorescence Intensity (MFI) value at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% greater than an unmodified CD80 control in a binding assay such as described in Example 6.

[0088] The term “biological half-life” refers to the amount of time it takes for a substance, such as an immunomodulatory polypeptide comprising a variant CD80 polypeptide of the present invention, to lose half of its pharmacologic or physiologic activity or concentration. Biological half-life can be affected by elimination, excretion, degradation (e.g., enzymatic) of the substance, or absorption and concentration in certain organs or tissues of the body. In some embodiments, biological half-life can be assessed by determining the time it takes for the blood plasma concentration of the substance to reach half its steady state level (“plasma half-life”). Conjugates that can be used to derivatize and increase the biological half-life of polypeptides of the invention are known in the art and include, but are not limited to, polyethylene glycol (PEG), hydroxyethyl starch (HES), XTEN (extended recombinant peptides; see, WO2013130683), human serum albumin (HSA), bovine serum albumin (BSA), lipids (acylation), and poly-Pro-Ala-Ser (PAS), polyglutamic acid (glutamylation).

[0089] The term “chimeric antigen receptor” or “CAR” as used herein refers to an artificial (i.e., man-made) transmembrane protein expressed on a mammalian cell comprising at least an ectodomain, a transmembrane, and an endodomain. Optionally, the CAR protein includes a “spacer” which covalently links the ectodomain to the transmembrane domain. A spacer is often a polypeptide linking the ectodomain to the transmembrane domain via peptide bonds. The CAR is typically expressed on a mammalian lymphocyte. In some embodiments, the CAR is expressed on a mammalian cell such as a T-cell or a tumor infiltrating lymphocyte (TIL). A CAR expressed on a T-cell is referred to herein as a “CAR T-cell” or “CAR-T.” In some embodiments the CAR-T is a T helper cell, a cytotoxic T-cell, a natural killer T-cell, a memory T-cell, a regulatory T-cell, or a gamma delta T-cell. When used clinically in, e.g. adoptive cell transfer, a CAR-T with antigen binding specificity to the patient's tumor is typically engineered to express on a native T-cell obtained from the patient. The engineered T-cell expressing the CAR is then infused back into the patient. The CAR-T is thus often an autologous CAR-T although allogeneic CAR-T are included within the scope of the invention. The ectodomain of a CAR comprises an antigen binding region, such as an antibody or antigen binding fragment thereof (e.g. scFv), that specifically binds under physiological conditions with a target antigen, such as a tumor specific antigen Upon specific binding a biochemical chain of events (i.e., signal 2023203586 08 Jun 2023 transduction) results in modulation of the immunological activity of the CAR-T. Thus, for example, upon specific binding by the antigen binding region of the CAR-T to its target antigen can lead to changes in the immunological activity of the T-cell activity as reflected by changes in cytotoxicity, proliferation or cytokine production. Signal transduction upon CAR-T activation is achieved in some embodiments by the CD3-zeta chain (“CD3-z”) which is involved in signal transduction in native mammalian T-cells. CAR-Ts can further comprise multiple signaling domains such as CD28, 4IBB or OX40, to further modulate immunomodulatory response of the T-cell. CD3-z comprises a conserved motif known as an immunoreceptor tyrosine-based activation motif (ITAM) which is involved in T-cell receptor signal transduction.

[0090] The term “collectively” or “collective” when used in reference to cytokine production induced by the presence of two or more variant CD80 polypeptides in an in vitro assay, means the overall cytokine expression level irrespective of the cytokine production induced by individual variant CD80 polypeptides. In some embodiments, the cytokine being assayed is IFN-gamma in an in vitro primary T-cell assay such as described in Example 7.

[0091] The term “cognate binding partner” (used interchangeably with “counter-structure”) in reference to a polypeptide, such as in reference to an IgSF domain ofa variant CD80, refers to at least one molecule (typically a native mammalian protein) to which the referenced polypeptide specifically binds under specific binding conditions. In some aspects, a variant CD80 containing an affinity modified IgSF domain specifically binds to the counter-structure of the corresponding native or wildtype CD80 but with increased or attenuated affinity. A species of ligand recognized and specifically binding to its cognate receptor under specific binding conditions is an example of a counter-structure or cognate binding partner of that receptor. A “cognate cell surface binding partner” is a cognate binding partner expressed on a mammalian cell surface. A “cell surface molecular species” is a cognate binding partner of ligands of the immunological synapse (IS), expressed on and by cells, such as mammalian cells, forming the immunological synapse.

[0092] As used herein, “conjugate,” “conjugation” or grammatical variations thereof refers the joining or linking together of two or more compounds resulting in the formation of another compound, by any joining or linking methods known in the art. It can also refer to a compound which is generated by the joining or linking together two or more compounds. For example, a variant CD80 polypeptide linked directly or indirectly to one or more chemical moieties or 2023203586 08 Jun 2023 polypeptide is an exemplary conjugate. Such conjugates include fusion proteins, those produced by chemical conjugates and those produced by any other methods.

[0093] The term “competitive binding” as used herein means that a protein is capable of specifically binding to at least two cognate binding partners but that specific binding of one cognate binding partner inhibits, such as prevents or precludes, simultaneous binding of the second cognate binding partner. Thus, in some cases, it is not possible for a protein to bind the two cognate binding partners at the same time. Generally, competitive binders contain the same or overlapping binding site for specific binding but this is not a requirement. In some embodiments, competitive binding causes a measurable inhibition (partial or complete) of specific binding of a protein to one of its cognate binding partner due to specific binding of a second cognate binding partner. A variety of methods are known to quantify competitive binding such as ELISA (enzyme linked immunosorbent assay) assays.

[0094] The term “conservative amino acid substitution” as used herein means an amino acid substitution in which an amino acid residue is substituted by another amino acid residue having a side chain R group with similar chemical properties (e.g., charge or hydrophobicity). Examples of groups of amino acids that have side chains with similar chemical properties include 1) aliphatic side chains: glycine, alanine, valine, leucine, and isoleucine; 2) aliphatic-hydroxyl side chains: serine and threonine; 3) amide-containing side chains: asparagine and glutamine; 4) aromatic side chains: phenylalanine, tyrosine, and tryptophan; 5) basic side chains: lysine, arginine, and histidine; 6) acidic side chains: aspartic acid and glutamic acid; and 7) sulfurcontaining side chains: cysteine and methionine. Conservative amino acids substitution groups are: valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, glutamateaspartate, and asparagine-glutamine.

[0095] The term, “corresponding to” with reference to positions of a protein, such as recitation that nucleotides or amino acid positions “correspond to” nucleotides or amino acid positions in a disclosed sequence, such as set forth in the Sequence Listing, refers to nucleotides or amino acid positions identified upon alignment with the disclosed sequence based on structural sequence alignment or using a standard alignment algorithm, such as the GAP algorithm. For example, corresponding residues can be determined by alignment of a reference sequence with the sequence of wild-type CD80 set forth in SEQ ID NO:28 (ECD domain) or set forth in SEQ ID NO: 152 or 372 (IgV domain) by structural alignment methods as described 2023203586 08 Jun 2023 herein. By aligning the sequences, one skilled in the art can identify corresponding residues, for example, using conserved and identical amino acid residues as guides.

[0096] The terms “decrease” or “attenuate” “or suppress” as used herein means to decrease by a statistically significant amount. A decrease can be at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%.

[0097] The terms “derivatives” or “derivatized” refer to modification of a protein by covalently linking it, directly or indirectly, to a composition so as to alter such characteristics as biological half-life, bioavailability, immunogenicity, solubility, toxicity, potency, or efficacy while retaining or enhancing its therapeutic benefit. Derivatives of immunomodulatory polypeptides of the invention are within the scope of the invention and can be made by, for example, glycosylation, pegylation, lipidation, or Fc-fusion.

[0098] As used herein, domain (typically a sequence of three or more, generally 5 or 7 or more amino acids, such as 10 to 200 amino acid residues) refers to a portion of a molecule, such as a protein or encoding nucleic acid, that is structurally and / or functionally distinct from other portions of the molecule and is identifiable. For example, domains include those portions of a polypeptide chain that can form an independently folded structure within a protein made up of one or more structural motifs and / or that is recognized by virtue of a functional activity, such as binding activity. A protein can have one, or more than one, distinct domains. For example, a domain can be identified, defined or distinguished by homology of the primary sequence or structure to related family members, such as homology to motifs. In another example, a domain can be distinguished by its function, such as an ability to interact with a biomolecule, such as a cognate binding partner. A domain independently can exhibit a biological function or activity such that the domain independently or fused to another molecule can perform an activity, such as, for example binding. A domain can be a linear sequence of amino acids or a non-linear sequence of amino acids. Many polypeptides contain a plurality of domains. Such domains are known, and can be identified by those of skill in the art. For exemplification herein, definitions are provided, but it is understood that it is well within the skill in the art to recognize particular domains by name. If needed appropriate software can be employed to identify domains.

[0099] The term “ectodomain” as used herein refers to the region of a membrane protein, such as a transmembrane protein, that lies outside the vesicular membrane. Ectodomains often comprise binding domains that specifically bind to ligands or cell surface receptors, such as via a 2023203586 08 Jun 2023 binding domain that specifically binds to the ligand or cell surface receptor. The ectodomain of a cellular transmembrane protein is alternately referred to as an extracellular domain.

[0100] The terms “effective amount” or “therapeutically effective amount” refer to a quantity and / or concentration of a therapeutic composition of the invention, including a protein composition or cell composition, that when administered ex vivo (by contact with a cell from a patient) or in vivo (by administration into a patient) either alone (i.e., as a monotherapy) or in combination with additional therapeutic agents, yields a statistically significant decrease in disease progression as, for example, by ameliorating or eliminating symptoms and / or the cause of the disease. An effective amount may be an amount that relieves, lessens, or alleviates at least one symptom or biological response or effect associated with a disease or disorder, prevents progression of the disease or disorder, or improves physical functioning of the patient. In the case of cell therapy, the effective amount is an effective dose or number of cells administered to a patient by adoptive cell therapy. In some embodiments the patient is a mammal such as a nonhuman primate or human patient.

[0101] The term “endodomain” as used herein refers to the region found in some membrane proteins, such as transmembrane proteins, that extends into the interior space defined by the cell surface membrane. In mammalian cells, the endodomain is the cytoplasmic region of the membrane protein. In cells, the endodomain interacts with intracellular constituents and can be play a role in signal transduction and thus, in some cases, can be an intracellular signaling domain. The endodomain of a cellular transmembrane protein is alternately referred to as a cytoplasmic domain, which, in some cases, can be a cytoplasmic signaling domain.

[0102] The terms “enhanced” or “increased” as used herein in the context of increasing immunological activity of a mammalian lymphocyte means to increase one or more activities the lymphocyte. An increased activity can be one or more of increase cell survival, cell proliferation, cytokine production, or T-cell cytotoxicity, such as by a statistically significant amount. In some embodiments, reference to increased immunological activity means to increase interferon gamma (IFN-gamma) production, such as by a statistically significant amount. In some embodiments, the immunological activity can be assessed in a mixed lymphocyte reaction (MLR) assay. Methods of conducting MLR assays are known in the art. Wang et al., Cancer Immunol Res. 2014 Sep: 2(9):846-56. Other methods of assessing activities of lymphocytes are known in the art, including any assay as described herein. In some embodiments an enhancement can be an 2023203586 08 Jun 2023 increase of at least 10%, 20%, 30%, 40%, 50%, 75%,100%, 200%, 300%, 400%, or 500% greater than a non-zero control value.

[0103] The term “engineered cell” as used herein refers to a mammalian cell that has been genetically modified by human intervention such as by recombinant DNA methods or viral transduction. In some embodiments, the cell is an immune cell, such as a lymphocyte (e.g. T cell, B cell, NK cell) or an antigen presenting cell (e.g. dendritic cell). The cell can be a primary cell from a patient or can be a cell line, hi some embodiments, an engineered cell of the invention comprises a variant CD80 of the invention engineered to modulate immunological activity of a T-cell expressing CD28, PD-L1 and / or CTLA-4, or an APC expressing PD-L1, to which the variant CD80 polypeptide specifically binds. In some embodiments, the variant 80 is a transmembrane immunomodulatory protein (hereinafter referred to as “TIP”) containing the extracellular domain or a portion thereof containing the IgV domain linked to a transmembrane domain (e.g. a CD80 transmembrane domain) and, optionally, an intracellular signaling domain. In some cases, the TIP is formatted as a chimeric receptor containing a heterologous cytoplasmic signaling domain or endodomain. In some embodiments, an engineered cell is capable of expressing and secreting a immunomodulatory protein as described herein. Among provided engineered cells also are cells further containing an engineered T-cell receptor (TCR) or chimeric antigen receptor (CAR).

[0104] The term “engineered T-cell” as used herein refers to a T-cell such as a T helper cell, cytotoxic T-cell (alternatively, cytotoxic T lymphocyte or CTL), natural killer T-cell, regulatory T-cell, memory T-cell, or gamma delta T-cell, that has been genetically modified by human intervention such as by recombinant DNA methods or viral transduction methods. An engineered T-cell comprises a variant CD80 transmembrane immunomodulatory protein (TIP) of the present invention that is expressed on the T-cell and is engineered to modulate immunological activity of the engineered T-cell itself, or a mammalian cell to which the variant CD80 expressed on the T-cell specifically binds.

[0105] The term “engineered T-cell receptor” or “engineered TCR” refers to a T-cell receptor (TCR) engineered to specifically bind with a desired affinity to a major histocompatibility complex (MHC) / peptide target antigen that is selected, cloned, and / or subsequently introduced into a population of T-cells, often used for adoptive immunotherapy. In contrast to engineered TCRs, CARs are engineered to bind target antigens in a MHC independent manner. 2023203586 08 Jun 2023

[0106] The term “expressed on” as used herein is used in reference to a protein expressed on the surface of a cell, such as a mammalian cell. Thus, the protein is expressed as a membrane protein. In some embodiments, the expressed protein is a transmembrane protein. In some embodiments, the protein is conjugated to a small molecule moiety such as a drug or detectable label. Proteins expressed on the surface of a cell can include cell-surface proteins such as cell surface receptors that are expressed on mammalian cells.

[0107] The term “half-life extending moiety” refers to a moiety of a polypeptide fusion or chemical conjugate that extends the half-life of a protein circulating in mammalian blood serum compared to the half-life of the protein that is not so conjugated to the moiety. In some embodiments, half-life is extended by greater than or greater than about 1.2-fold, 1.5-fold, 2.0-fold, 3.0-fold, 4.0-fold., 5.0-fold, or 6.0-fold. In some embodiments, half-life is extended by more than 6 hours, more than 12 hours, more than 24 hours, more than 48 hours, more than 72 hours, more than 96 hours or more than 1 week after in vivo administration compared to the protein without the half-life extending moiety. The half-life refers to the amount of time it takes for the protein to lose half of its concentration, amount, or activity. Half-life can be determined for example, by using an ELISA assay or an activity assay. Exemplary half-life extending moieties include an Fc domain, a multimerization domain, polyethylene glycol (PEG), hydroxyethyl starch (HES), XTEN (extended recombinant peptides; see, WO2013130683), human serum albumin (HSA), bovine serum albumin (BSA), lipids (acylation), and poly-Pro-Ala-Ser (PAS), and polyglutamic acid (glutamylation).

[0108] The term “immunological synapse” or “immune synapse” as used herein means the interface between a mammalian cell that expresses MHC I (major histocompatibility complex) or MHC II, such as an antigen-presenting cell or tumor cell, and a mammalian lymphocyte such as an effector T cell or Natural Killer (NK) cell.

[0109] An Fc (fragment crystallizable) region or domain of an immunoglobulin molecule (also termed an Fc polypeptide) corresponds largely to the constant region of the immunoglobulin heavy chain, and is responsible for various functions, including the antibody’s effector function(s). The Fc domain contains part or all of a hinge domain of an immunoglobulin molecule plus a CH2 and a CH3 domain. The Fc domain can form a dimer of two polypeptide chains joined by one or more disulfide bonds. In some embodiments, the Fc is a variant Fc that exhibits reduced (e.g. reduced greater than 30%, 40%, 50%, 60%, 70%, 80%, 90% or more) activity to facilitate an effector function. In some embodiments, reference to amino acid 2023203586 08 Jun 2023 substitutions in an Fc region is by EU numbering system unless described with reference to a specific SEQ ID NO. EU numbering is known and is according to the most recently updated IMGT Scientific Chart (IMGT®, the international ImMunoGeneTics information system®, http: / / www.imgt.org / IMGTScientificChart / Numbering / Hu_IGHGnber.html (created: 17 May 2001, last updated: 10 Jan 2013) and the EU index as reported in Kabat, E.A. et al. Sequences of Proteins of Immunological interest. 5th ed. US Department of Health and Human Services, NIH publication No. 91-3242 (1991 ).

[0110] An immunoglobulin Fc fusion (“Fc-fusion”), such as an immunomodulatory Fc fusion protein, is a molecule comprising one or more polypeptides (or one or more small molecules) operably linked to an Fc region of an immunoglobulin. An Fc-fusion may comprise, for example, the Fc region of an antibody (which facilitates pharmacokinetics) and a variant CD80 polypeptide. An immunoglobulin Fc region may be linked indirectly or directly to one or more variant CD80 polypeptides or small molecules (fusion partners). Various linkers are known in the art and can optionally be used to link an Fc to a fusion partner to generate an Fc-fusion. Fc-fusions of identical species can be dimerized to form Fc-fusion homodimers, or using nonidentical species to form Fc-fusion heterodimers. In some embodiments, the Fc is a mammalian Fc such as a murine or human Fc.

[0111] The term “host cell” refers to a cell that can be used to express a protein encoded by a recombinant expression vector. A host cell can be a prokaryote, for example, E. coli, or it can be a eukaryote, for example, a single-celled eukaryote (e.g., a yeast or other fungus), a plant cell (e.g., a tobacco or tomato plant cell), an animal cell (e.g., a human cell, a monkey cell, a hamster cell, a rat cell, a mouse cell, or an insect cell) or a hybridoma. Examples of host cells include Chinese hamster ovary (CHO) cells or their derivatives such as Veggie CHO and related cell lines which grow in serum-free media or CHO strain DX-B11, which is deficient in DHFR. In some embodiments, a host cell can be a mammalian cell (e.g., a human cell, a monkey cell, a hamster cell, a rat cell, a mouse cell, or an insect cell).

[0112] The term “immunoglobulin” (abbreviated “Ig”) as used herein refers to a mammalian immunoglobulin protein including any of the five human classes of antibody: IgA (which includes subclasses IgAl and IgA2), IgD, IgE, IgG (which includes subclasses IgGl, IgG2, IgG3, and IgG4), and IgM. The term is also inclusive of immunoglobulins that are less than fulllength, whether wholly or partially synthetic (e.g., recombinant or chemical synthesis) or naturally produced, such as antigen binding fragment (Fab), variable fragment (Fv) containing 2023203586 08 Jun 2023 VH and VL, the single chain variable fragment (scFv) containing VH and VL linked together in one chain, as well as other antibody V region fragments, such as Fab', F(ab)2, F(ab')2, dsFv diabody, Fc, and Fd polypeptide fragments. Bispecific antibodies, homobispecific and heterobispecific, are included within the meaning of the term.

[0113] The term “immunoglobulin superfamily” or “IgSF” as used herein means the group of cell surface and soluble proteins that are involved in the recognition, binding, or adhesion processes of cells. Molecules are categorized as members of this superfamily based on shared structural features with immunoglobulins (i.e., antibodies); they all possess a domain known as an immunoglobulin domain or fold. Members of the IgSF include cell surface antigen receptors, co-receptors and co-stimulatory molecules of the immune system, molecules involved in antigen presentation to lymphocytes, cell adhesion molecules, certain cytokine receptors and intracellular muscle proteins. They are commonly associated with roles in the immune system. Proteins in the immunological synapse are often members of the IgSF. IgSF can also be classified into “subfamilies” based on shared properties such as function. Such subfamilies typically consist of from 4 to 30 IgSF members.

[0114] The terms “IgSF domain” or “immunoglobulin domain” or “Ig domain” as used herein refers to a structural domain of IgSF proteins. Ig domains are named after the immunoglobulin molecules. They contain about 70-110 amino acids and are categorized according to their size and function. Ig-domains possess a characteristic Ig-fold, which has a sandwich-like structure formed by two sheets of antiparallel beta strands. Interactions between hydrophobic amino acids on the inner side of the sandwich and highly conserved disulfide bonds formed between cysteine residues in the B and F strands, stabilize the Ig-fold. One end of the Ig domain has a section called the complementarity determining region that is important for the specificity of antibodies for their ligands. The Ig like domains can be classified (into classes) as: IgV, IgCl, IgC2, or Igl. Most Ig domains are either variable (IgV) or constant (IgC). IgV domains with 9 beta strands are generally longer than IgC domains with 7 beta strands. Ig domains of some members of the IgSF resemble IgV domains in the amino acid sequence, yet are similar in size to IgC domains. These are called IgC2 domains, while standard IgC domains are called IgCl domains. T-cell receptor (TCR) chains contain two Ig domains in the extracellular portion; one IgV domain at the N-terminus and one IgCl domain adjacent to the cell membrane. CD80 contains two Ig domains: IgV and IgC. 2023203586 08 Jun 2023

[0115] The term “IgSF species” as used herein means an ensemble of IgSF member proteins with identical or substantially identical primary amino acid sequence. Each mammalian immunoglobulin superfamily (IgSF) member defines a unique identity of all IgSF species that belong to that IgSF member. Thus, each IgSF family member is unique from other IgSF family members and, accordingly, each species of a particular IgSF family member is unique from the species of another IgSF family member. Nevertheless, variation between molecules that are of the same IgSF species may occur owing to differences in post-translational modification such as glycosylation, phosphorylation, ubiquitination, nitrosylation, methylation, acetylation, and lipidation. Additionally, minor sequence differences within a single IgSF species owing to gene polymorphisms constitute another form of variation within a single IgSF species as do wild type truncated forms of IgSF species owing to, for example, proteolytic cleavage. A “cell surface IgSF species” is an IgSF species expressed on the surface of a cell, generally a mammalian cell.

[0116] The term “immunological activity” as used herein in the context of mammalian lymphocytes such as T-cells refers to one or more cell survival, cell proliferation, cytokine production (e.g. interferon-gamma), or T-cell cytotoxicity activities. In some cases, an immunological activity can means their expression of cytokines, such as chemokines or interleukins. Assays for determining enhancement or suppression of immunological activity include the MLR (mixed lymphocyte reaction) assays measuring interferon-gamma cytokine levels in culture supernatants (Wang et al., Cancer Immunol Res. 2014 Sep: 2(9):846-56), SEB (staphylococcal enterotoxin B) T cell stimulation assay (Wang et al., Cancer Immunol Res. 2014 Sep: 2(9):846-56), and anti-CD3 T cell stimulation assays (Li and Kurlander, J Transl Med. 2010: 8: 104). Since T cell activation is associated with secretion of IFN-gamma cytokine, detecting IFN-gamma levels in culture supernatants from these in vitro human T cell assays can be assayed using commercial ELISA kits (Wu et al, Immunol Lett 2008 Apr 15; 117(1): 57-62). Induction of an immune response results in an increase in immunological activity relative to quiescent lymphocytes. An immunomodulatory protein, such as a variant CD80 polypeptide containing an affinity modified IgSF domain, as provided herein can in some embodiments increase or, in alternative embodiments, decrease IFN-gamma (interferon-gamma) expression in a primary T-cell assay relative to a wild-type IgSF member or IgSF domain control. Those of skill will recognize that the format of the primary T-cell assay used to determine an increase in IFN-gamma expression will differ from that employed to assay for a decrease in IFN-gamma expression. In assaying for the ability of an immunomodulatory protein or affinity modified 2023203586 08 Jun 2023 IgSF domain of the invention to decrease IFN-gamma expression in a primary T-cell assay, a Mixed Lymphocyte Reaction (MLR) assay can be used as described in Example 6. Conveniently, a soluble form of an affinity modified IgSF domain of the invention can be employed to determine its ability to antagonize and thereby decrease the IFN-gamma expression in a MLR as likewise described in Example 6. Alternatively, in assaying for the ability of an immunomodulatory protein or affinity modified IgSF domain of the invention to increase IFN-gamma expression in a primary T-cell assay, a co-immobilization assay can be used. In a coimmobilization assay, a T-cell receptor signal, provided in some embodiments by anti-CD3 antibody, is used in conjunction with a co-immobilized affinity modified IgSF domain, such as a variant CD80, to determine the ability to increase IFN-gamma expression relative to a wild-type IgSF domain control. Methods to assay the immunological activity of engineered cells, including to evaluate the activity of a variant CD80 transmembrane immunomodulatory protein, are known in the art and include, but are not limited to, the ability to expand T cells following antigen stimulation, sustain T cell expansion in the absence of re- stimulation, and anti-cancer activities in appropriate animal models. Assays also include assays to assess cytotoxicity, including a standard 51Cr-release assay (see e.g. Milone et al., (2009) Molecular Therapy 17: 1453-1464) or flow based cytotoxicity assays, or an impedance based cytotoxicity assay (Peper et al. (2014) Journal of Immunological Methods, 405:192-198).

[0117] An “immunomodulatory polypeptide” is a polypeptide that modulates immunological activity. By “modulation” or “modulating” an immune response is meant that immunological activity is either increased or decreased. An immunomodulatory polypeptide can be a single polypeptide chain or a multimer (dimers or higher order multimers) of at least two polypeptide chains covalently bonded to each other by, for example, interchain disulfide bonds. Thus, monomeric, dimeric, and higher order multimeric polypeptides are within the scope of the defined term. Multimeric polypeptides can be homomultimeric (of identical polypeptide chains) or heteromultimeric (of non-identical polypeptide chains). An immunomodulatory polypeptide can comprise variant CD80.

[0118] The term “increase” as used herein means to increase by a statistically significant amount. An increase can be at least 5%, 10%, 20%, 30%, 40%, 50%, 75%, 100%, or greater than a non-zero control value. 2023203586 08 Jun 2023

[0119] An “isoform” of CD80 is one of a plurality of naturally occurring CD80 polypeptides that differ in amino acid sequence. Isoforms can be the product of splice variants of an RNA transcript expressed by a single gene, or the expression product of highly similar but different genes yielding a functionally similar protein such as may occur from gene duplication. As used herein, the term “isoform” of CD80 also refers to the product of different alleles of a CD80 gene.

[0120] The term “lymphocyte” as used herein means any of three subtypes of white blood cell in a mammalian immune system. They include natural killer cells (NK cells) (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity). T cells include: T helper cells, cytotoxic T-cells, natural killer T-cells, memory T-cells, regulatory T-cells, or gamma delta T-cells. Innate lymphoid cells (ILC) are also included within the definition of lymphocyte.

[0121] The terms “mammal,” or “patient” specifically includes reference to at least one of a: human, chimpanzee, rhesus monkey, cynomolgus monkey, dog, cat, mouse, or rat.

[0122] The term “membrane protein” as used herein means a protein that, under physiological conditions, is attached directly or indirectly to a lipid bilayer. A lipid bilayer that forms a membrane can be a biological membrane such as a eukaryotic (e.g., mammalian) cell membrane or an artificial (i.e., man-made) membrane such as that found on a liposome. Attachment of a membrane protein to the lipid bilayer can be by way of covalent attachment, or by way of non-covalent interactions such as hydrophobic or electrostatic interactions. A membrane protein can be an integral membrane protein or a peripheral membrane protein. Membrane proteins that are peripheral membrane proteins are non-covalently attached to the lipid bilayer or non-covalently attached to an integral membrane protein. A peripheral membrane protein forms a temporary attachment to the lipid bilayer such that under the range of conditions that are physiological in a mammal, peripheral membrane protein can associate and / or disassociate from the lipid bilayer. In contrast to peripheral membrane proteins, integral membrane proteins form a substantially permanent attachment to the membrane's lipid bilayer such that under the range of conditions that are physiological in a mammal, integral membrane proteins do not disassociate from their attachment to the lipid bilayer. A membrane protein can form an attachment to the membrane by way of one layer of the lipid bilayer (monotopic), or attached by way of both layers of the membrane (polytopic). An integral membrane protein that interacts with only one lipid bilayer is an “integral monotopic protein”. An integral membrane 2023203586 08 Jun 2023 protein that interacts with both lipid bilayers is an “integral polytopic protein” alternatively referred to herein as a “transmembrane protein”.

[0123] The terms “modulating” or “modulate” as used herein in the context of an immune response, such as a mammalian immune response, refer to any alteration, such as an increase or a decrease, of existing or potential immune responses that occurs as a result of administration of an immunomodulatory polypeptide comprising a variant CD80 of the present invention or as a result of administration of engineered cells expresses an immunomodulatory protein, such as a variant CD80 transmembrane immunomodulatory protein of the present invention. Thus, it refers to an alteration, such as an increase or decrease, of an immune response as compared to the immune response that occurs or is present in the absence of the administration of the immunomodulatory protein comprising the variant CD80. Such modulation includes any induction, activation, suppression or alteration in degree or extent of immunological activity of an immune cell. Immune cells include B cells, T cells, NK (natural killer) cells, NK T cells, professional antigenpresenting cells (APCs), and non-professional antigen-presenting cells, and inflammatory cells (neutrophils, macrophages, monocytes, eosinophils, and basophils). Modulation includes any change imparted on an existing immune response, a developing immune response, a potential immune response, or the capacity to induce, regulate, influence, or respond to an immune response. Modulation includes any alteration in the expression and / or function of genes, proteins and / or other molecules in immune cells as part of an immune response. Modulation of an immune response or modulation of immunological activity includes, for example, the following: elimination, deletion, or sequestration of immune cells; induction or generation of immune cells that can modulate the functional capacity of other cells such as autoreactive lymphocytes, antigen presenting cells, or inflammatory cells; induction of an unresponsive state in immune cells (i.e., anergy); enhancing or suppressing the activity or function of immune cells, including but not limited to altering the pattern of proteins expressed by these cells. Examples include altered production and / or secretion of certain classes of molecules such as cytokines, chemokines, growth factors, transcription factors, kinases, costimulatory molecules, or other cell surface receptors or any combination of these modulatory events. Modulation can be assessed, for example, by an alteration in IFN-gamma (interferon gamma) expression relative to the wild-type or unmodified CD80 control in a primary T cell assay (see, Zhao and Ji, Exp Cell Res. 2016 Jani; 340(1) 132-138). Modulation can be assessed, for example, by an alteration of an immunological activity of engineered cells, such as an alteration in in cytotoxic activity of 2023203586 08 Jun 2023 engineered cells or an alteration in cytokine secretion of engineered cells relative to cells engineered with a wild-type CD80 transmembrane protein.

[0124] The term, a “multimerization domain” refers to a sequence of amino acids that promotes stable interaction of a polypeptide molecule with one or more additional polypeptide molecules, each containing a complementary multimerization domain, which can be the same or a different multimerization domain to form a stable multimer with the first domain. Generally, a polypeptide is joined directly or indirectly to the multimerization domain. Exemplary multimerization domains include the immunoglobulin sequences or portions thereof, leucine zippers, hydrophobic regions, hydrophilic regions, and compatible protein-protein interaction domains. The multimerization domain, for example, can be an immunoglobulin constant region or domain, such as, for example, the Fc domain or portions thereof from IgG, including IgGl, IgG2, IgG3 or IgG4 subtypes, IgA, IgE, IgD and IgM and modified forms thereof.

[0125] The terms “nucleic acid” and “polynucleotide” are used interchangeably to refer to a polymer of nucleic acid residues (e.g., deoxyribonucleotides or ribonucleotides) in either single-or double-stranded form. Unless specifically limited, the terms encompass nucleic acids containing known analogues of natural nucleotides and that have similar binding properties to it and are metabolized in a manner similar to naturally-occurring nucleotides. Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses conservatively modified variants thereof (e.g., degenerate codon substitutions) and complementary nucleotide sequences as well as the sequence explicitly indicated (a “reference sequence”). Specifically, degenerate codon substitutions may be achieved by generating sequences in which the third position of one or more selected (or all) codons is substituted with mixed-base and / or deoxyinosine residues. The term nucleic acid or polynucleotide encompasses cDNA or mRNA encoded by a gene.

[0126] The term “molecular species” as used herein means an ensemble of proteins with identical or substantially identical primary amino acid sequence. Each mammalian immunoglobulin superfamily (IgSF) member defines a collection of identical or substantially identical molecular species. Thus, for example, human CD80 is an IgSF member and each human CD80 molecule is a molecular species of CD80. Variation between molecules that are of the same molecular species may occur owing to differences in post-translational modification such as glycosylation, phosphorylation, ubiquitination, nitrosylation, methylation, acetylation, and lipidation. Additionally, minor sequence differences within a single molecular species owing to gene polymorphisms constitute another form of variation within a single molecular species as 2023203586 08 Jun 2023 do wild type truncated forms of a single molecular species owing to, for example, proteolytic cleavage. A “cell surface molecular species” is a molecular species expressed on the surface of a mammalian cell. Two or more different species of protein, each of which is present exclusively on one or exclusively the other (but not both) of the two mammalian cells forming the IS, are said to be in “cis” or “cis configuration” with each other. Two different species of protein, the first of which is exclusively present on one of the two mammalian cells forming the IS and the second of which is present exclusively on the second of the two mammalian cells forming the IS, are said to be in “trans” or “trans configuration.” Two different species of protein each of which is present on both of the two mammalian cells forming the IS are in both cis and trans configurations on these cells.

[0127] The term “non-competitive binding” as used herein means the ability of a protein to specifically bind simultaneously to at least two cognate binding partners. Thus, the protein is able to bind to at least two different cognate binding partners at the same time, although the binding interaction need not be for the same duration such that, in some cases, the protein is specifically bound to only one of the cognate binding partners. In some embodiments, the binding occurs under specific binding conditions. In some embodiments, the simultaneous binding is such that binding of one cognate binding partner does not substantially inhibit simultaneous binding to a second cognate binding partner. In some embodiments, noncompetitive binding means that binding a second cognate binding partner to its binding site on the protein does not displace the binding of a first cognate binding partner to its binding site on the protein. Methods of assessing non-competitive binding are well known in the art such as the method described in Perez de La Lastra et al., Immunology, 1999 Apr: 96(4): 663-670. In some cases, in non-competitive interactions, the first cognate binding partner specifically binds at an interaction site that does not overlap with the interaction site of the second cognate binding partner such that binding of the second cognate binding partner does not directly interfere with the binding of the first cognate binding partner. Thus, any effect on binding of the cognate binding partner by the binding of the second cognate binding partner is through a mechanism other than direct interference with the binding of the first cognate binding partner. For example, in the context of enzyme-substrate interactions, a non-competitive inhibitor binds to a site other than the active site of the enzyme. Non-competitive binding encompasses uncompetitive binding interactions in which a second cognate binding partner specifically binds at an interaction site that does not overlap with the binding of the first cognate binding partner but binds to the second 2023203586 08 Jun 2023 interaction site only when the first interaction site is occupied by the first cognate binding partner.

[0128] The term “pharmaceutical composition” refers to a composition suitable for pharmaceutical use in a mammalian subject, often a human. A pharmaceutical composition typically comprises an effective amount of an active agent (e.g., an immunomodulatory polypeptide comprising a variant CD80 or engineered cells expressing a variant CD80 transmembrane immunomodulatory protein) and a carrier, excipient, or diluent. The carrier, excipient, or diluent is typically a pharmaceutically acceptable carrier, excipient or diluent, respectively.

[0129] The terms “polypeptide” and “protein” are used interchangeably herein and refer to a molecular chain of two or more amino acids linked through peptide bonds. The terms do not refer to a specific length of the product. Thus, “peptides,” and “oligopeptides,” are included within the definition of polypeptide. The terms include post-translational modifications of the polypeptide, for example, glycosylation, acetylation, phosphorylation and the like. The terms also include molecules in which one or more amino acid analogs or non-canonical or unnatural amino acids that can be synthesized, or expressed recombinantly using known protein engineering techniques. In addition, proteins can be derivatized.

[0130] The term “primary T-cell assay” as used herein refers to an in vitro assay to measure interferon-gamma (“IFN-gamma”) expression. A variety of such primary T-cell assays are known in the art such as that described in Example 6. In a preferred embodiment, the assay used is anti-CD3 coimmobilization assay. In this assay, primary T cells are stimulated by anti-CD3 immobilized with or without additional recombinant proteins. Culture supernatants are harvested at timepoints, usually 24-72 hours. In another embodiment, the assay used is a mixed lymphocyte reaction (MLR). In this assay, primary T cells are simulated with allogenic APC. Culture supernatants are harvested at timepoints, usually 24-72 hours. Human IFN-gamma levels are measured in culture supernatants by standard ELISA techniques. Commercial kits are available from vendors and the assay is performed according to manufacturer’s recommendation.

[0131] The term “purified” as applied to nucleic acids, such as encoding immunomodulatory proteins of the invention, generally denotes a nucleic acid or polypeptide that is substantially free from other components as determined by analytical techniques well known in the art (e.g., a purified polypeptide or polynucleotide forms a discrete band in an electrophoretic gel, chromatographic eluate, and / or a media subjected to density gradient centrifugation). For 2023203586 08 Jun 2023 example, a nucleic acid or polypeptide that gives rise to essentially one band in an electrophoretic gel is “purified.” A purified nucleic acid or protein of the invention is at least about 50% pure, usually at least about 75%, 80%, 85%, 90%, 95%, 96%, 99% or more pure (e.g., percent by weight or on a molar basis).

[0132] The term “recombinant” indicates that the material (e.g., a nucleic acid or a polypeptide) has been artificially (i.e., non-naturally) altered by human intervention. The alteration can be performed on the material within, or removed from, its natural environment or state. For example, a “recombinant nucleic acid” is one that is made by recombining nucleic acids, e.g., during cloning, affinity modification, DNA shuffling or other well-known molecular biological procedures. A “recombinant DNA molecule,” is comprised of segments of DNA joined together by means of such molecular biological techniques. The term “recombinant protein” or “recombinant polypeptide” as used herein refers to a protein molecule which is expressed using a recombinant DNA molecule. A “recombinant host cell” is a cell that contains and / or expresses a recombinant nucleic acid or that is otherwise altered by genetic engineering, such as by introducing into the cell a nucleic acid molecule encoding a recombinant protein, such as a transmembrane immunomodulatory protein provided herein. Transcriptional control signals in eukaryotes comprise “promoter” and “enhancer” elements. Promoters and enhancers consist of short arrays of DNA sequences that interact specifically with cellular proteins involved in transcription. Promoter and enhancer elements have been isolated from a variety of eukaryotic sources including genes in yeast, insect and mammalian cells and viruses (analogous control elements, i.e., promoters, are also found in prokaryotes). The selection of a particular promoter and enhancer depends on what cell type is to be used to express the protein of interest. The terms “in operable combination,” “in operable order” and “operably linked” as used herein refer to the linkage of nucleic acid sequences in such a manner or orientation that a nucleic acid molecule capable of directing the transcription of a given gene and / or the synthesis of a desired protein molecule is produced.

[0133] The term “recombinant expression vector” as used herein refers to a DNA molecule containing a desired coding sequence and appropriate nucleic acid sequences necessary for the expression of the operably linked coding sequence in a particular host cell. Nucleic acid sequences necessary for expression in prokaryotes include a promoter, optionally an operator sequence, a ribosome binding site and possibly other sequences. Eukaryotic cells are known to utilize promoters, enhancers, and termination and polyadenylation signals. A secretory signal 2023203586 08 Jun 2023 peptide sequence can also, optionally, be encoded by the recombinant expression vector, operably linked to the coding sequence for the recombinant protein, such as a recombinant fusion protein, so that the expressed fusion protein can be secreted by the recombinant host cell, for easier isolation of the fusion protein from the cell, if desired. The term includes the vector as a self-replicating nucleic acid structure as well as the vector incorporated into the genome of a host cell into which it has been introduced. Among the vectors are viral vectors, such as lentiviral vectors.

[0134] The term “selectivity” refers to the preference of a subject protein, or polypeptide, for specific binding of one substrate, such as one cognate binding partner, compared to specific binding for another substrate, such as a different cognate binding partner of the subject protein. Selectivity can be reflected as a ratio of the binding activity (e.g. binding affinity) of a subject protein and a first substrate, such as a first cognate binding partner, (e.g., Kai) and the binding activity (e.g. binding affinity) of the same subject protein with a second cognate binding partner (e.g., K^).

[0135] The term “sequence identity” as used herein refers to the sequence identity between genes or proteins at the nucleotide or amino acid level, respectively. “Sequence identity” is a measure of identity between proteins at the amino acid level and a measure of identity between nucleic acids at nucleotide level. The protein sequence identity may be determined by comparing the amino acid sequence in a given position in each sequence when the sequences are aligned. Similarly, the nucleic acid sequence identity may be determined by comparing the nucleotide sequence in a given position in each sequence when the sequences are aligned. Methods for the alignment of sequences for comparison are well known in the art, such methods include GAP, BESTFIT, BLAST, FASTA and TFASTA. The BLAST algorithm calculates percent sequence identity and performs a statistical analysis of the similarity between the two sequences. The software for performing BLAST analysis is publicly available through the National Center for Biotechnology Infonnation (NCBI) website.

[0136] The term “soluble” as used herein in reference to proteins, means that the protein is not a membrane protein. In general, a soluble protein contains only the extracellular domain of an IgSF family member receptor, or a portion thereof containing an IgSF domain or domains or specific-binding fragments thereof, but does not contain the transmembrane domain. In some cases, solubility of a protein can be improved by linkage or attachment, directly or indirectly via 2023203586 08 Jun 2023 a linker, to an Fc domain, which, in some cases, also can improve the stability and / or half-life of the protein. In some aspects, a soluble protein is an Fc fusion protein.

[0137] The term “species” as used herein with respect to polypeptides or nucleic acids means an ensemble of molecules with identical or substantially identical sequences. Variation between polypeptides that are of the same species may occur owing to differences in post-translational modification such as glycosylation, phosphorylation, ubiquitination, nitrosylation, methylation, acetylation, and lipidation. Slightly truncated sequences of polypeptides that differ (or encode a difference) from the full length species at the amino-terminus or carbox yl-terminus by no more than 1, 2, or 3 amino acid residues are considered to be of a single species. Such microheterogeneities are a common feature of manufactured proteins.

[0138] The term “specific binding fragment” as used herein in reference to a full-length wildtype mammalian CD80 polypeptide or an IgV or an IgC domain thereof, means a polypeptide having a subsequence of an IgV and / or IgC domain and that specifically binds in vitro and / or in vivo to a mammalian CD28, mammalian PD-L1 and / or mammalian CTLA-4, such as a human or murine CD28, PD-L1, and / or CTLA-4. In some embodiments, the specific binding fragment of the CD80 IgV or the CD80 IgC is at least 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% the sequence length of the full-length wild-type sequence. The specific binding fragment can be altered in sequence to form the variant CD80.

[0139] The term “specifically binds” as used herein means the ability of a protein, under specific binding conditions, to bind to a target protein such that its affinity or avidity is at least 5 times as great, but optionally at least 10, 20, 30, 40, 50, 100, 250 or 500 times as great, or even at least 1000 times as great as the average affinity or avidity of the same protein to a collection of random peptides or polypeptides of sufficient statistical size. A specifically binding protein need not bind exclusively to a single target molecule but may specifically bind to a non-target molecule due to similarity in structural conformation between the target and non-target (e.g., paralogs or orthologs). Those of skill will recognize that specific binding to a molecule having the same function in a different species of animal (i.e., ortholog) or to a non-target molecule having a substantially similar epitope as the target molecule (e.g., paralog) is possible and does not detract from the specificity of binding which is determined relative to a statistically valid collection of unique non-targets (e.g., random polypeptides). Thus, a polypeptide of the invention may specifically bind to more than one distinct species of target molecule due to cross-reactivity. Solid-phase ELISA immunoassays or Biacore measurements can be used to determine specific 2023203586 08 Jun 2023 binding between two proteins. Generally, interactions between two binding proteins have dissociation constants (Kj) less than IxlO'5 M, and often as low as 1 x 10 12 M. In certain embodiments of the present disclosure, interactions between two binding proteins have dissociation constants of IxlO'6 M, IxlO'7 M, IxlO'8 M, IxlO'9 M, IxlO'10 M or IxlO'11 M.

[0140] The terms “surface expresses” or “surface expression” in reference to a mammalian cell expressing a polypeptide means that the polypeptide is expressed as a membrane protein. In some embodiments, the membrane protein is a transmembrane protein.

[0141] As used herein, “synthetic,” with reference to, for example, a synthetic nucleic acid molecule or a synthetic gene or a synthetic peptide refers to a nucleic acid molecule or polypeptide molecule that is produced by recombinant methods and / or by chemical synthesis methods.

[0142] The term “targeting moiety” as used herein refers to a composition that is covalently or non-covalently attached to, or physically encapsulates, a polypeptide comprising the variant CD80. The targeting moiety has specific binding affinity for a desired counter-structure such as a cell surface receptor (e.g., the B7 family member PD-L1), or a tumor antigen such as tumor specific antigen (TSA) or a tumor associated antigen (TAA) such as B7-H6. Typically, the desired counter-structure is localized on a specific tissue or cell-type. Targeting moieties include: antibodies, antigen binding fragment (Fab), variable fragment (Fv) containing VH and Vl, the single chain variable fragment (scFv) containing Vh and Vl linked together in one chain, as well as other antibody V region fragments, such as Fab', F(ab)2, F(ab')2, dsFv diabody, nanobodies, soluble receptors, receptor ligands, affinity matured receptors or ligands, as well as small molecule (<500 dalton) compositions (e.g., specific binding receptor compositions). Targeting moieties can also be attached covalently or non-covalently to the lipid membrane of liposomes that encapsulate a polypeptide of the present invention.

[0143] The term “transmembrane protein” as used herein means a membrane protein that substantially or completely spans a lipid bilayer such as those lipid bilayers found in a biological membrane such as a mammalian cell, or in an artificial construct such as a liposome. The transmembrane protein comprises a transmembrane domain (“transmembrane domain”) by which it is integrated into the lipid bilayer and by which the integration is thermodynamically stable under physiological conditions. Transmembrane domains are generally predictable from their amino acid sequence via any number of commercially available bioinformatics software applications on the basis of their elevated hydrophobicity relative to regions of the protein that 2023203586 08 Jun 2023 interact with aqueous environments (e.g., cytosol, extracellular fluid). A transmembrane domain is often a hydrophobic alpha helix that spans the membrane. A transmembrane protein can pass through the both layers of the lipid bilayer once or multiple times. A transmembrane protein includes the provided transmembrane immunomodulatory proteins described herein. In addition to the transmembrane domain, a transmembrane immunomodulatory protein of the invention further comprises an ectodomain and, in some embodiments, an endodomain.

[0144] The terms “treating,” “treatment,” or “therapy” of a disease or disorder as used herein mean slowing, stopping or reversing the disease or disorders progression, as evidenced by decreasing, cessation or elimination of either clinical or diagnostic symptoms, by administration of a therapeutic composition (e.g. containing an immunomodulatory protein or engineered cells) of the invention either alone or in combination with another compound as described herein. “Treating,” “treatment,” or “therapy” also means a decrease in the severity of symptoms in an acute or chronic disease or disorder or a decrease in the relapse rate as for example in the case of a relapsing or remitting autoimmune disease course or a decrease in inflammation in the case of an inflammatory aspect of an autoimmune disease. As used herein in the context of cancer, the terms “treatment” or, “inhibit,” “inhibiting” or “inhibition” of cancer refers to at least one of: a statistically significant decrease in the rate of tumor growth, a cessation of tumor growth, or a reduction in the size, mass, metabolic activity, or volume of the tumor, as measured by standard criteria such as, but not limited to, the Response Evaluation Criteria for Solid Tumors (RECIST), or a statistically significant increase in progression free survival (PFS) or overall survival (OS). “Preventing,” “prophylaxis,” or “prevention” of a disease or disorder as used in the context of this invention refers to the administration of an immunomodulatory polypeptide or engineered cells of the invention, either alone or in combination with another compound, to prevent the occurrence or onset of a disease or disorder or some or all of the symptoms of a disease or disorder or to lessen the likelihood of the onset of a disease or disorder.

[0145] The term “tumor specific antigen” or “TSA” as used herein refers to a counterstructure that is present primarily on tumor cells of a mammalian subject but generally not found on normal cells of the mammalian subject. A tumor specific antigen need not be exclusive to tumor cells but the percentage of cells of a particular mammal that have the tumor specific antigen is sufficiently high or the levels of the tumor specific antigen on the surface of the tumor are sufficiently high such that it can be targeted by anti-tumor therapeutics, such as immunomodulatory polypeptides of the invention, and provide prevention or treatment of the 2023203586 08 Jun 2023 mammal from the effects of the tumor. In some embodiments, in a random statistical sample of cells from a mammal with a tumor, at least 50% of the cells displaying a TSA are cancerous. In other embodiments, at least 60%, 70%, 80%, 85%, 90%, 95%, or 99% of the cells displaying a TSA are cancerous.

[0146] The term “variant” (also “modified” or mutant”) as used in reference to a variant CD80 means a CD80, such as a mammalian (e.g., human or murine) CD80 created by human intervention. The variant CD80 is a polypeptide having an altered amino acid sequence, relative to an unmodified or wild-type CD80. The variant CD80 is a polypeptide which differs from a wild-type CD80 isoform sequence by one or more amino acid substitutions, deletions, additions, or combinations thereof. For purposes herein, the variant CD80 contains at least one affinity modified domain, whereby one or more of the amino acid differences occurs in an IgSF domain (e.g. IgV domain). A variant CD80 can contain 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or more amino acid differences, such as amino acid substitutions. A variant CD80 polypeptide generally exhibits at least 50%, 60%, 70%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to a corresponding wild-type or unmodified CD80, such as to the sequence of SEQ ID NO:1, a mature sequence thereof or a portion thereof containing the extracellular domain or an IgSF domain thereof. In some embodiments, a variant CD80 polypeptide exhibits at least 50%, 60%, 70%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to a corresponding wildtype or unmodified CD80 comprising the sequence set forth in SEQ ID NO:28, SEQ ID NO: 152, or SEQ ID NO:372. Non-naturally occurring amino acids as well as naturally occurring amino acids are included within the scope of permissible substitutions or additions. A variant CD80 is not limited to any particular method of making and includes, for example, de novo chemical synthesis, de novo recombinant DNA techniques, or combinations thereof. A variant CD80 of the invention specifically binds to at least one or more of: CD28, PD-L1 and / or CTLA-4 of a mammalian species. In some embodiments, the altered amino acid sequence results in an an altered (i.e., increased or decreased) binding affinity or avidity to CD28, PD-L1 and / or CTLA-4 compared to the unmodified or wild-type CD80 protein. An increase or decrease in binding affinity or avidity can be determined using well known binding assays such as flow cytometry. Larsen et al., American Journal of Transplantation, Vol 5: 443-453 (2005). See also, Linsley et al., Immunity, 1: 7930801 (1994). An increase in variant CD80 binding affinity or avidity to 2023203586 08 Jun 2023 CD28, PD-L1 and / or CTLA-4 can be a value at least 5% greater than that of the unmodified or wild-type CD80 and in some embodiments, at least 10%, 15%, 20%, 30%, 40%, 50%, 100% greater than that of the unmodified or wild-type CD80 control value. A decrease in CD80 binding affinity or avidity to CD28, PD-L1 and / or CTLA-4 is to a value no greater than 95% of the of the unmodified or wild-type CD80 control values, and in some embodiments no greater than 80%, 70% 60%, 50%, 40%, 30%, 20%, 10%, 5%, or no detectable binding affinity or avidity of the unmodified or wild-type CD80 control values. A variant CD80 polypeptide is altered in primary amino acid sequence by substitution, addition, or deletion of amino acid residues. The term “variant” in the context of variant CD80 polypeptide is not be construed as imposing any condition for any particular starting composition or method by which the variant CD80 is created. A variant CD80 can, for example, be generated starting from wild type mammalian CD80 sequence information, then modeled in silico for binding to CD28, PD-L1 and / or CTLA-4, and finally recombinantly or chemically synthesized to yield the variant CD80. In but one alternative example, the variant CD80 can be created by site-directed mutagenesis of an unmodified or wild-type CD80. Thus, variant CD80 denotes a composition and not necessarily a product produced by any given process. A variety of techniques including recombinant methods, chemical synthesis, or combinations thereof, may be employed.

[0147] The term “wild-type” or “natural” or “native” as used herein is used in connection with biological materials such as nucleic acid molecules, proteins (e.g., CD80), IgSF members, host cells, and the like, refers to those which are found in nature and not modified by human intervention. II. VARIANT CD80 POLYPEPTIDES

[0148] Provided herein are variant CD80 polypeptides that exhibit altered (increased or decreased) binding activity or affinity for one or more CD80 cognate binding partners. In some embodiments, the CD80 cognate binding partner is CD28, PD-L1, or CTLA-4. In some embodiments, the variant CD80 polypeptide contains one or more amino acid modifications, such as one or more substitutions (alternatively, “mutations” or “replacements”), deletions or additions in an immunoglobulin superfamily (IgSF) domain (IgD) relative to a wild-type or unmodified CD80 polypeptide or a portion of a wild-type or unmodified CD80 containing the IgD or a specific binding fragment thereof. 2023203586 08 Jun 2023

[0149] Thus, a provided variant CD80 polypeptide is or comprises a variant IgD (hereinafter called “vlgD”) in which the one or more amino acid modifications (e.g., substitutions) is in an IgD.

[0150] In some embodiments, the IgD comprises an IgV domain or an IgC (e.g. IgC2) domain or specific binding fragment of the IgV domain or the IgC (e.g. IgC2) domain, or combinations thereof. In some embodiments, the IgD can be an IgV only, the combination of the IgV and IgC, including the entire extracellular domain (ECD), or any combination of Ig domains of CD80. Table 2 provides exemplary residues that correspond to IgV or IgC regions of CD80. In some embodiments, the variant CD80 polypeptide contains an IgV domain, or an IgC domain, or specific binding fragments thereof in which the at least one amino acid modification (e.g., substitution) in the IgV domain or IgC domain or the specific binding fragment thereof. In some embodiments, the variant CD80 polypeptide contains an IgV domain or specific binding fragments thereof in which the at least one of the amino acid modifications (e.g., substitutions) is in the IgV domain or a specific binding fragment thereof. In some embodiments, by virtue of the altered binding activity or affinity, the altered IgV domain or IgC domain is an affinity modified IgSF domain.

[0151] In some embodiments, the variant is modified in one more IgSF domains relative to the sequence of an unmodified CD80 sequence. In some embodiments, the unmodified CD80 sequence is a wild-type CD80. In some embodiments, the unmodified or wild-type CD80 has the sequence of a native CD80 or an ortholog thereof. In some embodiments, the unmodified CD80 is or comprises the extracellular domain (ECD) of CD80 or a portion thereof containing one or more IgSF domain (see Table 2). In some embodiments, the extracellular domain of an unmodified or wild-type CD80 polypeptide comprises an IgV domain and an IgC domain or domains. However, the variant CD80 polypeptide need not comprise both the IgV domain and the IgC domain or domains. In some embodiments, the variant CD80 polypeptide comprises or consists essentially of the IgV domain or a specific binding fragment thereof. In some embodiments, the variant CD80 polypeptide comprises or consists essentially of the IgC domain or specific binding fragments thereof. In some embodiments, the variant CD80 is soluble and lacks a transmembrane domain. In some embodiments, the variant CD80 further comprises a transmembrane domain and, in some cases, also a cytoplasmic domain. 2023203586 08 Jun 2023

[0152] In some embodiments, the wild-type or unmodified CD80 polypeptide is a mammalian CD80 polypeptide, such as, but not limited to, a human, a mouse, a cynomolgus monkey, or a rat CD80 polypeptide. In some embodiments, the wild-type or unmodified CD80 sequence is human.

[0153] In some embodiments, the wild-type or unmodified CD80 polypeptide has (i) the sequence of amino acids set forth in SEQ ID NO: 1 or a mature form thereof lacking the signal sequence, (ii) a sequence of amino acids that exhibits at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to SEQ ID NO: 1 or a mature form thereof, or (iii) is a portion of (i) or (ii) containing an IgV domain or IgC domain or specific binding fragments thereof.

[0154] In some embodiments, the wild-type or unmodified CD80 polypeptide is or comprises an extracellular domain of the CD80 or a portion thereof. For example, in some embodiments, the unmodified or wild-type CD80 polypeptide comprises the amino acid sequence set forth in SEQ ID NO: 28, or an ortholog thereof. For example, the unmodified or wild-type CD80 polypeptide can comprise (i) the sequence of amino acids set forth in SEQ ID NO:28, (ii) a sequence of amino acids that has at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to SEQ ID NO: 28, or (iii) is a specific binding fragment of of (i) or (ii) comprising an IgV domain or an IgC domain. In some embodiments, the wild-type or unmodified extracellular domain of CD80 is capable of binding one or more CD80 cognate binding proteins, such as one or more of CD28, PD-L1 or CTLA-4.

[0155] In some embodiments, the wild-type or unmodified CD80 polypeptide contains an IgV domain or an IgC domain, or a specific binding fragment thereof. In some embodiments, the IgV domain of the wild-type or unmodified CD80 polypeptide comprises the amino acid sequence set forth in SEQ ID NO: 152 or 372, or an ortholog thereof. For example, the IgV domain of the unmodified or wild-type CD80 polypeptide can contain (i) the sequence of amino acids set forth in SEQ ID NO: 152 or 372, (ii) a sequence of amino acids that has at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to SEQ ID NO: 152 or 372, or (iii) is a specific binding fragment of (i) or (ii). In some embodiments, the wild-type or unmodified IgV domain is capable of binding one or more CD80 cognate binding proteins, such as one or more of CD28, PD-L1 or CTLA-4. 2023203586 08 Jun 2023

[0156] In some embodiments, the IgC domain of the wild-type or unmodified CD80 polypeptide comprises the amino acid sequence set forth as residues 145-230 or 154-232 of SEQ ID NO: 1, or an ortholog thereof. For example, the IgC domain of the unmodified or wild-type CD80 polypeptide can contain (i) the sequence of amino acids set forth residues 145-230 or 154232 of SEQ ID NO: 1, (ii) a sequence of amino acids that has at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity to residues 145-230 or 154-232 of SEQ ID NO: 1, or (iii) is a specific binding fragment of (i) or (ii). In some embodiments, the wild-type or unmodified IgC domain is capable of binding one or more CD80 cognate binding proteins.

[0157] In some embodiments, the wild-type or unmodified CD80 polypeptide contains a specific binding fragment of CD80, such as a specific binding fragment of the IgV domain or the IgC domain. In some embodiments the specific binding fragment can bind CD28, PD-L1, and / or CTLA-4. The specific binding fragment can have an amino acid length of at least 50 amino acids, such as at least 60, 70, 80, 90, 100, or 110 amino acids. In some embodiments, the specific binding fragment of the IgV domain contains an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% of the length of the IgV domain set forth as amino acids 35-135 or 37-138 of SEQ ID NO: 1. In some embodiments, the specific binding fragment of the IgC domain comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% of the length of the IgC domain set forth as amino acids 145-230 or 154232 of SEQ ID NO: 1.

[0158] In some embodiments, the variant CD80 polypeptide comprises the ECD domain or a portion thereof comprising one or more affinity modified IgSF domains. In some embodiments, the variant CD80 polypeptides can comprise an IgV domain or an IgC domain, or a specific binding fragment of the IgV domain or a specific binding fragment of the IgC domain in which at least one of the IgV or IgC domain contains the one or more amino acid modifications (e.g., substitutions). In some embodiments, the variant CD80 polypeptides can comprise an IgV domain and an IgC domain, or a specific binding fragment of the IgV domain and a specific binding fragment of the IgC domain. In some embodiments, the variant CD80 polypeptide comprises a full-length IgV domain. In some embodiments, the variant CD80 polypeptide comprises a full-length IgC domain. In some embodiments, the variant CD80 polypeptide comprises a specific binding fragment of the IgV domain. In some embodiments, the variant 2023203586 08 Jun 2023 CD80 polypeptide comprises a specific binding fragment of the IgC domain. In some embodiments, the variant CD80 polypeptide comprises a full-length IgV domain and a fulllength IgC domain. In some embodiments, the variant CD80 polypeptide comprises a fulllength IgV domain and a specific binding fragment of an IgC domain. In some embodiments, the variant CD80 polypeptide comprises a specific binding fragment of an IgV domain and a fulllength IgC domain. In some embodiments, the variant CD80 polypeptide comprises a specific binding fragment of an IgV domain and a specific binding fragment of an IgC domain.

[0159] In any of such embodiments, the one or more amino acid modifications (e.g., substitutions) of the variant CD80 polypeptides can be located in any one or more of the CD80 polypeptide domains. For example, in some embodiments, one or more amino acid modifications (e.g., substitutions) are located in the extracellular domain of the variant CD80 polypeptide. In some embodiments, one or more amino acid modifications (e.g., substitutions) are located in the IgV domain or specific binding fragment of the IgV domain. In some embodiments, one or more amino acid modifications (e.g., substitutions) are located in the IgC domain or specific binding fragment of the IgC domain.

[0160] Generally, each of the various attributes of polypeptides are separately disclosed below (e.g., soluble and membrane bound polypeptides, affinity of CD80 for CD28, PD-L1, and CTLA-4, number of variations per polypeptide chain, number of linked polypeptide chains, the number and nature of amino acid alterations per variant CD80, etc.). However, as will be clear to the skilled artisan, any particular polypeptide can comprise a combination of these independent attributes. It is understood that reference to amino acids, including to a specific sequence set forth as a SEQ ID NO used to describe domain organization of an IgSF domain are for illustrative purposes and are not meant to limit the scope of the embodiments provided. It is understood that polypeptides and the description of domains thereof are theoretically derived based on homology analysis and alignments with similar molecules. Thus, the exact locus can vary, and is not necessarily the same for each protein. Hence, the specific IgSF domain, such as specific IgV domain or IgC domain, can be several amino acids (such as one, two, three or four) longer or shorter.

[0161] Further, various embodiments of the invention as discussed below are frequently provided within the meaning of a defined term as disclosed above. The embodiments described in a particular definition are therefore to be interpreted as being incorporated by reference when the defined term is utilized in discussing the various aspects and attributes described herein. 2023203586 08 Jun 2023 Thus, the headings, the order of presentation of the various aspects and embodiments, and the separate disclosure of each independent attribute is not meant to be a limitation to the scope of the present disclosure. Exemplary Modifications

[0162] Provided herein are variant CD80 polypeptides containing at least one affinity-modified IgSF domain (e.g. IgV or IgC) or a specific binding fragment thereof relative to an IgSF domain contained in a wild-type or unmodified CD80 polypeptide such that the variant CD80 polypeptide exhibits altered (increased or decreased) binding activity or affinity for one or more ligands CD28, PD-L1 or CTLA-4 compared to a wild-type or unmodified CD80 polypeptide. In some embodiments, a variant CD80 polypeptide has a binding affinity for CD28, PD-L1, and / or CTLA-4 that differs from that of a wild-type or unmodified CD80 polypeptide control sequence as determined by, for example, solid-phase ELISA immunoassays, flow cytometry or Biacore assays. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28, PD-L1, and / or CTLA-4. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28, PD-L1, and / or CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. The CD28, PD-L1 and / or the CTLA-4 can be a mammalian protein, such as a human protein or a murine protein.

[0163] Binding affinities for each of the cognate binding partners are independent; that is, in some embodiments, a variant CD80 polypeptide has an increased binding affinity for one, two or three of CD28, PD-L1, and CTLA-4, and / or a decreased binding affinity for one, two or three of CD28, PD-L1, and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide.

[0164] In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. 2023203586 08 Jun 2023

[0165] In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28 and PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28 and a decreased binding affinity for PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28 and PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28 and an increased binding affinity for PD-L1, relative to a wild-type or unmodified CD80 polypeptide.

[0166] In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28 and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28 and a decreased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28 and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28 and an increased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide.

[0167] In some embodiments, the variant CD80 polypeptide has an increased binding affinity for PD-L1 and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for PD-L1 and a decreased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for PD-L1 and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for PD-L1 and an increased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide.

[0168] In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28, PD-L1, and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28 and PD-L1, and a decreased binding affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28 and CTLA-4, and a decreased binding affinity for PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28 and PD-L1, and an increased binding 2023203586 08 Jun 2023 affinity for CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28 and an increased binding affinity for PD-L1 and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has an increased binding affinity for CD28, and a decreased binding affinity for PD-L1 and CTLA-4, relative to a wildtype or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28, CTLA-4, and PD-L1, relative to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide has a decreased binding affinity for CD28, and an increased binding affinity for PD-L1 and CTLA-4, relative to a wild-type or unmodified CD80 polypeptide.

[0169] In some embodiments, a variant CD80 polypeptide with increased or greater binding affinity to CD28, PD-L1, and / or CTLA-4 will have an increase in binding affinity relative to the wild-type or unmodified CD80 polypeptide control of at least about 5%, such as at least about 10%, 15%, 20%, 25%, 35%, or 50% for the CD28, PD-L1, and / or CTLA-4. In some embodiments, the increase in binding affinity relative to the wild-type or unmodified CD80 polypeptide is more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9fold, 10-fold, 20-fold, 30-fold 40-fold or 50-fold. In such examples, the wild-type or unmodified CD80 polypeptide has the same sequence as the variant CD80 polypeptide except that it does not contain the one or more amino acid modifications (e.g., substitutions).

[0170] In some embodiments, a variant CD80 polypeptide with decreased or reduced binding affinity to CD28, PD-L1, and / or CTLA-4 will have decrease in binding affinity relative to the wild-type or unmodified CD80 polypeptide control of at least 5%, such as at least about 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or more for the CD28, PD-L1, and / or CTLA-4. In some embodiments, the decrease in binding affinity relative to the wild-type or unmodified CD80 polypeptide is more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8fold, 9-fold, 10-fold, 20-fold, 30-fold 40-fold or 50-fold. In such examples, the wild-type or unmodified CD80 polypeptide has the same sequence as the variant CD80 polypeptide except that it does not contain the one or more amino acid modifications (e.g., substitutions).

[0171] In some embodiments, the equilibrium dissociation constant (Ka) of any of the foregoing embodiments to CD28, PD-L1, and / or CTLA-4 can be less than 1x10'5M, IxlO’6 M, IxlO'7 M, IxlO'8 M, IxlO'9 M, IxlO'10 M or IxlO'11 M, or IxlO42 M. 2023203586 08 Jun 2023

[0172] The wild-type or unmodified CD80 sequence does not necessarily have to be used as a starting composition to generate variant CD80 polypeptides described herein. Therefore, use of the term “substitution” does not imply that the provided embodiments are limited to a particular method of making variant CD80 polypeptides. Variants CD80 polypeptides can be made, for example, by de novo peptide synthesis and thus does not necessarily require a “substitution” in the sense of altering a codon to encode for the substitution. This principle also extends to the terms “addition” and “deletion” of an amino acid residue which likewise do not imply a particular method of making. The means by which the variant CD80 polypeptides are designed or created is not limited to any particular method. In some embodiments, however, a wild-type or unmodified CD80 encoding nucleic acid is mutagenized from wild-type or unmodified CD80 genetic material and screened for desired specific binding affinity and / or induction of IFN-gamma expression or other functional activity according to the methods disclosed in the Examples or other methods known to a skilled artisan. In some embodiments, a variant CD80 polypeptide is synthesized de novo utilizing protein or nucleic acid sequences available at any number of publicly available databases and then subsequently screened. The National Center for Biotechnology Information provides such information and its website is publicly accessible via the internet as is the UniProtKB database as discussed previously.

[0173] Unless stated otherwise, as indicated throughout the present disclosure, the amino acid substitution(s) are designated by amino acid position number corresponding to the numbering of positions of the unmodified ECD sequence set forth in SEQ ID NO:28 or also, where applicable, the unmodified IgV sequence set forth in SEQ ID NO: 152 or 372 (containing residues 1-101 or 1-107, respectively, of SEQ ID NO:28 depending on annotation convention) as follows: VIHVTKEVKEVATLSCGHNVSVEELAQTRIYWQKEKKMVLTMMSGDMNIWPEYKN RTIFDITNNLSIVILALRPSDEGTYECVVLKYEKDAFKREHLAEVTLSVKADFPTPSISD FEIPTSNIRRIICSTSGGFPEPHLSWLENGEELNAINTTVSQDPETELYAVSSKLDFNMTT NHSFMCLIKYGHLRVNQTFNWNTTKQEHFPDN (SEQ ID NO:28) VIHVTKEVKEVATLSCGHNVSVEELAQTRIYWQKEKKMVLTMMSGDMNIWPEYKN RTIFDITNNLSIVILALRPSDEGTYECVVLKYEKDAFKREHLAEVT (SEQ ID NO: 152) 2023203586 08 Jun 2023 VIHVTKEVKEVATLSCGHNVSVEELAQTRIYWQKEKKMVLTMMSGDMNIWPEYKN RTIFDITNNLSIVIQALRPSDEGTYECVVLKYEKDGFKREHLAEVTLSVKAD (SEQ ID NO:372)

[0174] It is within the level of a skilled artisan to identify the corresponding position of a modification, e.g. amino acid substitution, in a CD80 polypeptide, including portion thereof containing an IgSF domain (e.g. IgV) thereof, such as by alignment of a reference sequence with SEQ ID NO:28 or SEQ ID NO: 152 or SEQ ID NO:372. In the listing of modifications throughout this disclosure, the amino acid position is indicated in the middle, with the corresponding unmodified (e.g. wild-type) amino acid listed before the number and the identified variant amino acid substitution listed after the number. If the modification is a deletion of the position a “del” is indicated and if the modification is an insertion at the position an “ins” is indicated.

[0175] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) in a wild-type or unmodified CD80 sequence. The one or more amino acid modifications (e.g., substitutions) can be in the ectodomain (extracellular domain) of the wild-type or unmodified CD80 sequence, such as the extracellular domain. In some embodiments, the one or more amino acid modifications (e.g., substitutions) are in the IgV domain or specific binding fragment thereof. In some embodiments, the one or more amino acid modifications (e.g., substitutions) are in the IgC domain or specific binding fragment thereof. In some embodiments of the variant CD80 polypeptide, some of the one or more amino acid modifications (e.g., substitutions) are in the IgV domain or a specific binding fragment thereof, and some of the one or more amino acid modifications (e.g., substitutions) are in the IgC domain or a specific binding fragment thereof.

[0176] In some embodiments, the variant CD80 polypeptide has up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid modifications (e.g., substitutions). The modifications (e.g., substitutions) can be in the IgV domain or the IgC domain. In some embodiments, the variant CD80 polypeptide has up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid modifications (e.g., substitutions) in the IgV domain or specific binding fragment thereof. In some embodiments, the variant CD80 polypeptide has up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid modifications (e.g., substitutions) in the IgC domain or specific binding fragment thereof. In some 2023203586 08 Jun 2023 embodiments, the variant CD80 polypeptide has at least about 85%, 86%, 86%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity with the wild-type or unmodified CD80 polypeptide or specific binding fragment thereof, such as the amino acid sequence of SEQ ID NO: 28, 152, or 372.

[0177] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) in an unmodified CD80 or specific binding fragment there of corresponding to position(s) 4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 24, 25, 27, 28, 29, 30, 31, 33, 36, 37, 38, 40, 41, 42, 43, 44, 47, 48, 50, 52, 53, 54, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 74, 76, 77, 80, 81, 83, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 99, 102, 103, 104, 107, 108, 109, 110, 114, 115, 116, 117, 118, 120, 121, 122, 126, 127, 128, 129, 130, 133, 137, 140, 142, 143, 144, 148, 149, 152, 154, 160, 162, 164, 168, 169, 174, 175, 177, 178, 183, 178, 185, 188, 190, 192, 193, or 199 with reference to numbering of SEQ ID NO: 28. In some embodiments, such variant CD80 polypeptides exhibit altered binding affinity to one or more of CD28, PD-L1, or CTLA-4 compared to the wild-type or unmodified CD80 polypeptide. For example, in some embodiments, the variant CD80 polypeptide exhibits increased binding affinity to CD28, PD-L1, and / or CTLA-4 compared to a wild-type or unmodified CD80 polypeptide. In some embodiments, the variant CD80 polypeptide exhibits decreased binding affinity to CD28, PD-L1, and / or CTLA-4 compared to a wild-type or unmodified CD80 polypeptide.

[0178] In some embodiments, the variant CD80 polypeptide has one or more amino acid substitution selected from V4M, K9E, E10R, VI IS, A12G, A12T, A12V, T13N, LUA. S15V, S15F, C16S, C16G, C16L, G17W, H18L, H18R, H18Y, V20L, S21P, V22A, E24G, L25P, Q27R, T28A, T28S, R29C, R29D, R29H, R29V, I30V, Y31F, Y31H, Y31L, Q33H, K36E, K36G, K37E, K37Q, M38I, M38L, M38T, M38V, L40M, T41A, T41G, T41D, T41I, M42T, M43I, M43Q, M43R, M43V, S44P, M47T, N48D, N48I, W50G, E52G, Y53C, K54M, F59L, F59S, D60V, I61N, T62S, N63S, N64S, L65H, S66H, I67F, I67T, V68A, V68M, I69T, L70Q, L70P, L70R, L72P, P74L, D76G, E77G, E77K, Y80N, E81A, E81R, E81V, V83A, V83I, L85I, L85R, K86E, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90L, D90N, A91E, A91G, A91S, A91T, F92L, F92N, F92P, F92Y, K93I, K93E, K93Q, K93R, K93V, R94G, R94L, R94F, E95K, H96R, L97R, E99D, E99G, L102S, S103L, S103P, V104A, V104L, D107N, F108L, P109S, P109H, T110A, S114T, D115G, F116S, F116L, E117V, E117G, I118V, I118A, I118T, T120S, S121P, N122S, I126L, I126V, I127T, C128Y, C128R, S129L, S129P, T130A, G133D, 2023203586 08 Jun 2023 P137L, S140T, L142S, E143G, N144D, N144S, L148S, N149D, N149S, N152T, T154I, T154A, E160G, E162G, Y164H, S168G, K169E, K169I, K169S, M174T, M174V, T175A, N177S, H178R, L183H, K185E, H188D, H188Q, R190S, N192D, Q193L, or T199S. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of V4M, K9E, E10R, VI IS, A12G, A12T, A12V, T13N, L14A, S15V, S15F, C16S, C16G, C16L, G17W, H18L, H18R, H18Y, V20L, S21P, V22A, E24G, L25P, Q27R, T28A, T28S, R29C, R29D, R29H, R29V, I30V, Y31F, Y31H, Y31L, Q33H, K36E, K36G, K37E, K37Q, M38I, M38L, M38T, M38V, L40M, T41A, T41G, T41D, T41I, M42T, M43I, M43Q, M43R, M43V, S44P, M47T, N48D, N48I, W50G, E52G, Y53C, K54M, F59L, F59S, D60V, I61N, T62S, N63S, N64S, L65H, S66H, I67F, I67T, V68A, V68M, I69T, L70Q, L70P, L70R, L72P, P74L, D76G, E77G, E77K, Y80N, E81A, E81R, E81V, V83A, V83I, L85I, L85R, K86E, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90L, D90N, A91E, A91G, A91S, A91T, F92L, F92N, F92P, F92Y, K93I, K93E, K93Q, K93R, K93V, R94G, R94L, R94F, E95K, H96R, L97R, E99D, E99G, L102S, S103L, S103P, V104A, V104L, D107N, F108L, P109S, P109H, T110A, S114T, D115G, F116S, F116L, E117V, E117G, I118V, I118A, I118T, T120S, S121P, N122S, I126L, I126V, I127T, C128Y, C128R, S129L, S129P, T130A, G133D, P137L, S140T, L142S, E143G, N144D, N144S, L148S, N149D, N149S, N152T, T154I, T154A, E160G, E162G, Y164H, S168G, K169E, K169I, K169S, M174T, M174V, T175A, N177S, H178R, L183H, K185E, H188D, H188Q, R190S, N192D, Q193L, T199S or a conservative amino acid substitution thereof.

[0179] In some embodiments, the one or more amino acid modification, e.g. substitution is L70Q / A91G, L70Q / A91G / T130A, L70Q / A91G / I118A / T120S / T130A, V4M / L70Q / A91G / T120S / T130A, L70Q / A91G / T120S / T130A, V20L / L70Q / A91S / T120S / T130A, S44P / L70Q / A91 G / T 130A, L70Q / A91G / E117G / T120S / T130A, A91 G / T 120S / T130A, L70R / A91 G / T 120S / T130A, L70Q / E81A / A91 G / T 120S / 1127T / T130A, L70Q / Y87N / A91 G / T 130A, T28S / L70Q / A91G / E95K / T120S / T130A, N63S / L70Q / A91 G / T 120S / T130A, K36E / I67T / L70Q / A91 G / T 120S / T130A / N152T, E52G / L70Q / A91 G / T 120S / T130A, K37E / F59S / L70Q / A91G / T120S / T130A, A91G / S103P, K89E / T130A, D60V / A91 G / T 120S / T130A, K54M / A91 G / T 120S, M38T / L70Q / E77G / A91 G / T 120S / T130A / N152T, R29H / E52G / L70R / E88G / A91 G / T 130A, Y31H / T41G / L70Q / A91G / T120S / T130A, V68A / T110A, S66H / D90G / T110A / F116L, 2023203586 08 Jun 2023 R29H / E52G / T120S / T130A, A91G / L102S, I67T / L70Q / A91G / T120S, L70Q / A91 G / T 11OA / T120S / T130A, M38V / T41D / M43I / W50G / D76G / V83A / K89E / T120S / T130A, V22A / L70Q / S121P, A12 V / S15F / Y31H / T41 G / T 130A / P137L / N152T, I67F / L70R / E88G / A91 G / T 120S / T130A, E24G / L25P / L70Q / T120S, A91G / F92L / F108L / T120S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, E24G / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / H96R / N149S / C182S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29V / M43Q / E81R / L85I / K89R / D90L / A91E / F92N / K93Q / R94G, T41PA91G, K89R / D90K / A91G / F92Y / K93R / N122S / N177S, K89R / D90K / A91G / F92Y / K93R, K36G / K37Q / M38I / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / E99G / T130A / N149S, E88D / K89R / D90K / A91G / F92Y / K93R, K36G / K37Q / M38VL40M, R29H / Y31H / T41G / Y87N / E8 8G / K89E / D90N / A91G / P109S, A12T / H18L / M43V / F59L / E77K / P109S / I118T, R29V / Y31F / K36G / M38L / M43Q / E81R / V83I / L85I / K89R / D90L / A91E / F92N / K93Q / R94G, V68M / L70P / L72P / K86E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / T130A / M174T, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / H188D, 2023203586 08 Jun 2023 H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91 T / F92P / K93V / R94L / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38ET41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / E143G / K169E / M174V / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L85R / K89N / A91T / F92P / K93V / R94L / T120 S / I127T / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / F108L / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / T120S / T130A / K169E / H18 8D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / T120S / I127T / C128Y / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / T130A / K169E, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / T120S / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A, 2023203586 08 Jun 2023 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A / L148S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / I61N / E81V / L85R / K89N / A91T / F92P / K93V / R94F / V104 A / T120S / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / F92P / K93V / R94F / I118 V / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / T62S / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / T130A / K169E / T175A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / F116S / T130A / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / L142S / H188D, C16S / H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T11OA / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / A91G / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / D76G / A91G / S103L / T120S / I127T / T 130A, DELTAQ33 / Y53C / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E, T62S / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / S129L / H188D, K9E / E10R / V11S / A12G / T13N / K14A / S15V / C16L / G17W / H18Y / Y53C / L70Q / D90G / T130A / N14 9D / N152T / H188D, H18L / R29D / Y31L / Q33H / K36G / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / Il 18V / T120S / I127T / T130A / H188D, K89E / K93E / T130A, S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / N48W68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / P109H / I126L / K169I, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91 T / F92P / K93V / R94L / L97R, S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / D90 N / A91T / F92P / K93 V / R94L / T130A / N149S / E162G, 2023203586 08 Jun 2023 H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S / R190S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91 T / F92P / K93 V / R94L / T130A / R190S, C16G / V22A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / D76G / E81V / L85R / K8 9N / A91T / F92P / K93V / R94L / I118T / T130A / S140T / N149S / K169VH178R / N192D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / E117V / I118T / N149S / S168G / H188Q, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / I118T / T130A / N149S / K169I, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / D115G / I118T / T130A / G133D / N149S, S129P, A91G / S129P, I69T / L70Q / A91G / T120S, Y31H / S129P, T28A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / V104L / T130A / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S / H188Q, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / T130 A / N149S / T1541, A12G / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / L97R / T130A / L183H, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / S140T / N149S / K169S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169VQ193L, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 2023203586 08 Jun 2023 V / R94L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169I, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / T130A / N149S / K169I, I118T / C128R, Q27R / R29C / M42T / S129P / E160G, S129P / T154A, S21P / L70Q / D90G / T120S / T130A, L70Q / A91G / N144D, L70Q / A91G / I118A / T120S / T130A / K169E, V4M / L70Q / A91G / I118V / T120S / T130A / K169E, L70Q / A91G / 1118 V / T120S / T130A / K169E, L70Q / A91G / 1118V / T120S / T130A, V20L / L70Q / A91S / I118V / T120S / T130A, L70Q / A91G / E117G / I118V / T120S / T130A, A91G / 1118V / T 120S / T130A, L70R / A91G / 1118V / T 120S / T130A / T199S, L70Q / E81A / A91G / I118V / T120S / I127T / T130A, T28S / L70Q / A91G / E95K / I118V / T120S / I126V / T130A / K169E, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, K3 6E / I67T / L70Q / A91G / 1118 V / T 120S / T130A / N152T, E52G / L70Q / A91G / D107N / I118 V / T120S / T130A / K169E, K37E / F59S / L70Q / A91G / 1118 V / T 120S / T130A / K185E, D60V / A91G / 1118V / T 120S / T130AK169E, K54M / L70Q / A91G / Y164H / T120S, M3 8T / L70Q / E77G / A91G / 1118 V / T 120S / T130 A / N152T, Y31H / T41G / M43L / L70Q / A91G / I118V / T120S / I126V / T130A, L65H / D90G / T110A / F116L, R29H / E52G / D90N / I118V / T120S / T130A, I67T / L70Q / A91G / I118V / T120S, L70Q / A91G / T110A / I118V / T120S / T130A, M38V / T41D / M43VW50G / D76G / V83A / K89E / I118V / T120S / I126V / T130A, A12V / S15F / Y31H / M3 8L / T41G / M43L / D90N / T130A / P137L / N149D / N152T, I67F / L70R / E88G / A91G / I118V / T120S / T130A, E24G / L25P / L70Q / A91G / I118V / T120S / N152T, A91G / F92L / F108L / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R / N122S / N177S, K36G / K37Q / M38I / L40M / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / E99G / T130A / N14 9S, K36G / L40M, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 2023203586 08 Jun 2023 V / R94L / I118V / T120S / I127T / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38ET41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / T130A / K169E / M174T, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N48D / F59L / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / I118V / T120S / I127T / T130A / H188D, H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91 T / F92P / K93V / R94L / I118V / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / E143G / K169E / M174V / H188D, R29D / I30V / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / K169E, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L85R / K89N / A91T / F92P / K93V / R94L / I118 V / T120S / I127T / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / F108L / I118V / T120S / T130A / K169E / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / T130A / N149D / K169E / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / 1118 V / T120S / T130A / K169E / H18 8D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118V / T120S / I127T / C128Y / T130A / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / E99D / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92 2023203586 08 Jun 2023 P / K93 V / R94L / I118 V / T120S / T130A / K169E, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / I61N / E81V / L85R / K89N / A91T / F92P / K93V / R94F / V104A / I118V / T120S / I126V / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / I118V / T120S / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / T62S / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / T130A / K169E / T175A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / L142S / H188D, C16S / H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T110A / I118V / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / A91G / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / D76G / A91G / S103L / I118V / T120S / I1 27T / T130A, Y53C / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / K169E, T62S / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E, Y53C / L70Q / D90G / T130A / N149D / N152T / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / H188D, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S.

[0180] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) in an unmodified CD80 or specific binding fragment there of corresponding to position(s) 4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 24, 25, 27, 28, 29, 31, 33, 36, 37, 38, 40, 41, 42, 43, 44, 47, 48, 50, 52, 53, 54, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 72, 74, 76, 77, 80, 81, 83, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 99, 102, 103, 104, 108, 109, 110, 115, 116, 117, 118, 120, 121, 122, 126, 127, 128, 129, 130, 133, 137, 140, 142, 143, 144, 148, 149, 152, 154, 160, 162, 168, 169, 174, 175, 177, 178, 183, 178, 188, 190, 192, or 193 with reference to numbering of SEQ ID NO: 28. In some embodiments, such variant CD80 polypeptides exhibit altered binding affinity to one or more of CD28, PD-L1, or CTLA-4 compared to the wild-type or unmodified CD80 polypeptide. For example, in some embodiments, the variant CD80 polypeptide exhibits increased binding affinity to CD28, PD-L1, and / or CTLA-4 compared to a wild-type or unmodified CD80 polypeptide. In some 2023203586 08 Jun 2023 embodiments, the variant CD80 polypeptide exhibits decreased binding affinity to CD28, PD-L1, and / or CTLA-4 compared to a wild-type or unmodified CD80 polypeptide.

[0181] In some embodiments, the variant CD80 polypeptide has one or more amino acid substitution selected from V4M, K9E, E10R, VI IS, A12G, A12T, A12V, T13N, L14A, S15V, S15F, C16S, C16G, C16L, G17W, H18L, H18R, H18Y, V20L, S21P, V22A, E24G, L25P, Q27R, T28A, T28S, R29C, R29D, R29H, R29V, Y31F, Y31H, Y31L, Q33H, K36E, K36G, K37E, K37Q, M38I, M38L, M38T, M38V, L40M, T41A, T41G, T41D, T41I, M42T, M43I, M43Q, M43R, M43V, S44P, M47T, N48I, W50G, E52G, Y53C, K54M, F59L, F59S, D60V, I61N, T62S, N63S, N64S, S66H, I67F, I67T, V68A, V68M, I69T, L70Q, L70P, L70R, L72P, P74L, D76G, E77G, E77K, Y80N, E81A, E81R, E81V, V83A, V83I, L85I, L85R, K86E, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90L, D90N, A91E, A91G, A91S, A91T, F92L, F92N, F92P, F92Y, K93I, K93E, K93Q, K93R, K93V, R94G, R94L, R94F, E95K, H96R, L97R, E99G, L102S, S103L, S103P, V104A, V104L, F108L, P109S, P109H, T110A, D115G, F116S, F116L, E117V, E117G, I118V, I118A, Il 18T, T120S, S121P, N122S, I126L, I127T, C128Y, C128R, S129L, S129P, T130A, G133D, P137L, S140T, L142S, E143G, N144S, L148S, N149D, N149S, N152T, T154I, T154A, E160G, E162G, S168G, K169E, K169I, K169S, M174T, M174V, T175A, N177S, H178R, L183H, H188D, H188Q, R190S, N192D, Q193L,. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of V4M, K9E, E10R, VI IS, A12G, A12T, A12V, T13N, L14A, S15V, S15F, C16S, C16G, C16L, G17W, H18L, H18R, H18Y, V20L, S21P, V22A, E24G, L25P, Q27R, T28A, T28S, R29C, R29D, R29H, R29V, Y31F, Y31H, Y31L, Q33H, K36E, K36G, K37E, K37Q, M38I, M38L, M38T, M38V, L40M, T41A, T41G, T41D, T41I, M42T, M43I, M43Q, M43R, M43V, S44P, M47T, N48I, W50G, E52G, Y53C, K54M, F59L, F59S, D60V, I61N, T62S, N63S, N64S, S66H, I67F, I67T, V68A, V68M, I69T, L70Q, L70P, L70R, L72P, P74L, D76G, E77G, E77K, Y80N, E81A, E81R, E81V, V83A, V83I, L85I, L85R, K86E, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90L, D90N, A91E, A91G, A91S, A91T, F92L, F92N, F92P, F92Y, K93I, K93E, K93Q, K93R, K93V, R94G, R94L, R94F, E95K, H96R, L97R, E99G, L102S, S103L, S103P, V104A, V104L, F108L, P109S, P109H, T110A, D115G, F116S, F116L, E117V, E117G, I118V, I118A, Il 18T, T120S, S121P, N122S, I126L, I127T, C128Y, C128R, S129L, S129P, T130A, G133D, P137L, S140T, L142S, E143G, N144S, L148S, N149D, N149S, N152T, T154I, T154A, E160G, E162G, S168G, K169E, K169I, K169S, M174T, 2023203586 08 Jun 2023 M174V, T175A, H178R, H178R, L183H, H188D, H188Q, R190S, N192D, Q193L, or a conservative amino acid substitution thereof.

[0182] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) in an unmodified CD80 or specific binding fragment there of corresponding to position(s) 30, 65, 107, 114, 164, 185, or 199 with reference to numbering of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitution selected from I30V, N48D, L65H, E99D, D107N, S114T, I126V, N144D, Y164H, and T199S. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of N48D, L65H, E99D, D107N, S114T, I126V, N144D, Y164H, K185E, T199S, or a conservative amino acid substitution thereof.

[0183] A conservative amino acid substitution is any amino acid that falls in the same class of amino acids as the substituted amino acids, other than the wild-type or unmodified amino acid. The classes of amino acids are aliphatic (glycine, alanine, valine, leucine, and isoleucine), hydroxyl or sulfur-containing (serine, cysteine, threonine, and methionine), cyclic (proline), aromatic (phenylalanine, tyrosine, tryptophan), basic (histidine, lysine, and arginine), and acidic / amide (aspartate, glutamate, asparagine, and glutamine). Thus, for example, a conservative amino acid substitution of the V4M substitution includesV4S, V4C, and V4T amino acid substitutions.

[0184] In some embodiments, the variant CD80 polypeptide comprises any of the substitutions (mutations) listed in Table 1. Table 1 also provides exemplary sequences by reference to SEQ ID NO for the extracellular domain (ECD) or IgV domain of wild-type CD80 or exemplary variant CD80 polypeptides. As indicated, the exact locus or residues corresponding to a given domain can vary, such as depending on the methods used to identify or classify the domain. Also, in some cases, adjacent N- and / or C-terminal amino acids of a given domain (e.g. IgV) also can be included in a sequence of a variant IgSF polypeptide, such as to ensure proper folding of the domain when expressed. Thus, it is understood that the exemplification of the SEQ ID NOs in Table 1 is not to be construed as limiting. For example, the particular domain, such as the IgV domain, of a variant CD80 polypeptide can be several amino acids longer or shorter, such as 1-10, e.g. 1, 2, 3, 4, 5, 6 or 7 amino acids longer or shorter, than the sequence of amino acids set forth in the respective SEQ ID NO. 2023203586 08 Jun 2023

[0185] In some embodiments, the variant CD80 polypeptide comprises any of the extracellular domain (ECD) sequences listed in Table 1 (i.e., any one of SEQ ID NOS: 55-108, 280-346, 414-475). In some embodiments, the variant CD80 polypeptide comprises a polypeptide sequence that exhibits at least 90% identity, at least 91% identity, at least 92% identity, at least 93% identity, at least 94% identity, at least 95% identity, such as at least 96% identity, 97% identity, 98% identity, or 99% identity to any of the extracellular domain (ECD) sequences listed in Table 1 (i.e., any one of SEQ ID NOS: 55-108, 280-346, 414-475) and contains the amino acid modification(s), e.g., substitution(s), not present in the wild-type or unmodified CD80. In some embodiments, the variant CD80 polypeptide comprises a specific binding fragment of any of the extracellular domain (ECD) sequences listed in Table 1 (i.e., any one of SEQ ID NOS: 55-108, 280-346, 414-475) and contains the amino acid modification(s), e.g., substitution(s), not present in the wild-type or unmodified CD80. In some embodiments, the variant CD80 polypeptide comprises any of the IgV sequences listed in Table 1 (i.e., any one of SEQ ID NOS: 153-195, 347, 373-386, 476-477). In some embodiments, the variant CD80 polypeptide comprises a polypeptide sequence that exhibits at least 90% identity, at least 91% identity, at least 92% identity, at least 93% identity, at least 94% identity, at least 95% identity, such as at least 96% identity, 97% identity, 98% identity, or 99% identity to any of the IgV sequences listed in Table 1 (i.e., any one of SEQ ID NOS: 153-195, 347, 373-386, 476-477) and contains the amino acid modification(s), e.g., substitution(s), not present in the wild-type or unmodified CD80. In some embodiments, the variant CD80 polypeptide comprises a specific binding fragment of any of the IgV sequences listed in Table 1 (i.e., any one of SEQ ID NOS: 153-195, 347, 373-386, 476-477) and contains the amino acid modification(s), e.g., substitution(s), not present in the wild-type or unmodified CD80.

[0186] Table 1 also provides exemplary sequences by reference to SEQ ID NO for the extracellular domain (ECD) or IgV domain of wild-type CD80 or exemplary variant CD80 polypeptides. As indicated, the exact locus or residues corresponding to a given domain can vary, such as depending on the methods used to identify or classify the domain. Also, in some cases, adjacent N- and / or C-terminal amino acids of a given domain (e.g. ECD) also can be included in a sequence of a variant IgSF polypeptide, such as to ensure proper folding of the domain when expressed. Thus, it is understood that the exemplification of the SEQ ID NOSs in Table 1 is not to be construed as limiting. For example, the particular domain, such as the IgV domain, of a variant CD80 polypeptide can be several amino acids longer or shorter, such as 1- 2023203586 08 Jun 2023 10, e.g. 1, 2, 3, 4, 5, 6 or 7 amino acids longer or shorter, than the sequence of amino acids set forth in the respective SEQ ID NO. TABLE 1: Exemplary variant CD80 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO Wild-type 28 152, 372 L70Q / A91G 55 153,374 L70Q / A91G / T130A 56 L70Q / A91G / 1118 A / T120S / T130A 57 V4M / L70Q / A91G / T120S / T130A 58 154 L70Q / A91 G / T 120S / T130A 59 V20L / L70Q / A91S / T120S / T130A 60 155 S44P / L70Q / A91 G / T 130A 61 156 L70Q / A91G / E117G / T120S / T130A 62 A91G / T120S / T130A 63 157 L70R / A91 G / T 120S / T130 A 64 158 L70Q / E81A / A91 G / T 120S / 1127T / T130A 65 159 L70Q / Y87N / A91 G / T 130A 66 160 T28 S / L70Q / A91G / E95 K / T120S / T130 A 67 161 N63 S / L70Q / A91 G / T 120S / T130 A 68 162 K3 6E / I67T / L70Q / A91 G / T 120S / T130 A / N152T 69 163 E52G / L70Q / A91 G / T 120S / T130A 70 164 K37E / F59S / L70Q / A91 G / T 120S / T130A 71 165 A91G / S103P 72 378 K89E / T130A 73 166,385 A91G 74 154, 375 D60V / A91 G / T 120S / T130A 75 167 K54M / A91G / T120S 76 168 M3 8T / L70Q / E77G / A91 G / T 120S / T130A / N152T 77 169 R29H / E52G / L70R / E8 8G / A91 G / T 130A 78 170 Y31H / T41G / L70Q / A91 G / T 120S / T130 A 79 171 V68A / T110A 80 172 S66H / D90G / T110A / F116L 81 173 R29H / E52G / T120S / T130A 82 174 A91G / L102S 83 386 I67T / L70Q / A91 G / T 120S 84 175 L70Q / A91 G / T 110A / T120S / T130A 85 M38V / T41D / M43I / W50G / D76G / V83A / K89E / T120S / T130A 86 176 V22A / L70Q / S121P 87 177 A12V / S15F / Y31H / T41 G / T 130A / P137L / N152T 88 178 I67F / L70R / E8 8G / A91 G / T 120S / T130A 89 179 E24G / L25P / L70Q / T120S 90 180 A91G / F92L / F108L / T120S 91 181 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / N149S 92 182 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / N144S / N149S 93 R29D / Y31L / Q33H / K36G / M3 81 / T41A / M42T / M43R / M47T / E81V / L85R / 94 183 2023203586 08 Jun 2023 TABLE 1: Exemplary variant CD80 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO K89N / A91T / F92P / K93 V / R94L / L148S / N149S E24G / R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / H96R / N149S / C182S 95 184 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / N149S 96 R29V / M43Q / E81R / L85I / K89R / D90L / A91E / F92N / K93Q / R94G 97 185,376 T41I / A91G 98 186,377 K89R / D90K / A91G / F92 Y / K93R / N122S / N177S 99 K89R / D90K / A91G / F92Y / K93R 100 187,373 K36G / K37Q / M38PF59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / E9 9G / T130A / N149S 101 188 E88D / K89R / D90K / A91G / F92Y / K93R 102 189,379 K36G / K37Q / M38PL40M 103 190, 380 K36G 104 191,381 R29H / Y31H / T41G / Y87N / E8 8G / K89E / D90N / A91 G / Pl 09S 105 192 A12T / H18L / M43 V / F59L / E77K / P109S / I118T 106 193 R29V / Y31F / K36G / M38L / M43Q / E81R / V83PL85I / K89R / D90L / A91E / F9 2N / K93Q / R94G 107 194, 382 V68M / L70P / L72P / K86E 108 195,383 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E 280 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A 281 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E 282 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / T130A / M174T 283 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / H18 8D 284 H18R / R29D / Y31L / Q33H / K36G / K37E / M3 81 / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / T130A / K169E / H18 8 D 285 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / E143G / K169E / M1 74V / H188D 286 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A 287 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / H18 8D 288 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E 289 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A 290 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / 1127T / T130A / K169E / H18 8D 291 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / F108L / T120S / T130A / K169E / H18 8D 292 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / 293 2023203586 08 Jun 2023 TABLE 1: Exemplary variant CD80 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO K89N / A91T / F92P / K93 V / R94L / T130A / H18 8D R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / K169E 294 H18L / R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / T130A / K169E / H18 8D 295 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / C128 Y / T130A / H18 8D 296 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / T130A / K169E 297 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A 298 H18L / R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / K169E 299 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A 300 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A / L148S 301 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118 V / T 120S / I127T / T130A / K169E 302 R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / I61N / E81V / L85R / K 89N / A91T / F92P / K93 V / R94F / V104A / T120S / T130A 303 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / F92P / K93V / R94F / I118V / T130A 304 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / T62S / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E / T175A 305 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / F116S / T130A / H188D 306 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / I127T / T130A / L142S / H18 8D 307 C16S / H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T11OA / H18 8D 308 R29D / Y31L / Q3 3H / K3 6G / M3 81 / T41A / M43R / M47T / A91G / T120S / 1127T / T13OA / H188D 309 R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / L70Q / D76G / A91G / S103L / T120S / I127T / T130A 310 DELTAQ33 / Y53O / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E 311 T62S / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T120S / T130A / K169E 312 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / S129L / H18 8D 313 K9E / E1OR / V11S / A12G / T13N / K14A / S15 V / C16L / G17W / H18 Y / Y53C / L 70Q / D90G / T130A / N149D / N152T / H188D 314 H18L / R29D / Y31L / Q33H / K36G / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118 V / T 120S / I127T / T130A / H18 8D 315 K89E / K93E / T130A 316 S21P / R29D / Y31L / Q3 3H / K3 6G / M3 81 / T41A / M43R / M47T / N48I / V68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / P109H / I126L / K169I 317 2023203586 08 Jun 2023 TABLE 1: Exemplary variant CD80 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO H18L / R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91T / F92P / K93V / R94L / L97R 318 347,384 S21P / R29D / Y31L / Q33 H / K36G / M 3 81 / T41A / M43R / M47T / P74L / Y80N / E 81V / L85R / K89N / D90N / A91T / F92P / K93 V / R94L / T130A / N149S / E162G 319 H18L / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A 320 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S / R190S 321 H18L / R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / R190S 322 C16G / V22A / R29D / Y31L / Q33H / K36G / M3 8I / T41A / M43R / M47T / V68M / D76G / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / S140T / N149S / K169I / H178R / N192D 323 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94F / E117V / I118T / N149S / S168G / H188Q 324 V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E8IV / L85R / K89N / A91T / F92P / K93 V / R94L / T130A 325 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93V / R94F / Il 18T / T130A / N149S / K169I 326 V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E8IV / L85R / K89N / A91T / F92P / K93V / R94L / D115G / I118T / T130A / G133D / N14 9S 327 S129P 328 A91G / S129P 329 I69T / L70Q / A91G / T120S 330 Y31H / S129P 331 T28A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / V104L / T130A / N149S 332 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S / H18 8Q 333 H18L / R29D / Y31L / Q33H / K36G / M3 81 / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S 334 H18L / R29D / Y31L / Q33H / K36G / M3 8PT41A / M43R / M47T / V68 A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T130A / N149S / T154I 335 A12G / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / T130A / L183H 336 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / S140T / N149S / K169S 337 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S / K169I / Q193L 338 V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / Il 18T / T130A / N149S 339 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S 340 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S / K1691 341 R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / T130A / N149S / K1691 342 2023203586 08 Jun 2023 TABLE 1: Exemplary variant CD80 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO I118T / C128R 343 Q27R / R29C / M42T / S129P / E160G 344 S129P / T154A 345 S21P / L70Q / D90G / T120S / T130 A 346 L70Q / A91G / N144D 414 L70Q / A91G / 1118 A / T120S / T130A / K169E 415 V4M / L70Q / A91G / 1118 V / T 120S / T130A / K169E 416 L70Q / A91G / 1118 V / T 120S / T130A / K169E 417 L70Q / A91G / 1118 V / T 120S / T130A 418 V20L / L70Q / A91S / 1118 V / T 120S / T130A 419 L70Q / A91G / E117G / 1118 V / T 120S / T130A 420 A91G / 1118 V / T 120S / T130A 421 L70R / A91G / 1118 V / T 120S / T130A / T199S 422 L70Q / E81A / A91G / 1118 V / T 120S / 1127T / T130A 423 T28S / L70Q / A91G / E95K / 1118 V / T 120S / 1126 V / T 130A / K169E 424 N63S / L70Q / A91G / S114T / I118V / T120S / T130A 425 K36E / I67T / L70Q / A91G / 1118 V / T 120S / T130A / N152T 426 E52G / L70Q / A91G / D107N / I118 V / Tl 20S / T130A / K169E 427 K37E / F59S / L70Q / A91G / 1118 V / T 120S / T130A / K185E 428 D60 V / A91G / 1118 V / T 120S / T130 AK169E 429 K54M / L70Q / A91G / Y164H / T120S 430 M38T / L70Q / E77G / A91G / 1118 V / T 120S / T130A / N152T 431 Y31H / T41G / M43L / L70Q / A91G / 1118 V / T 120S / 1126 V / T 130A 432 L65H / D90G / T110A / F116L 433 R29H / E52G / D90N / I118V / T120S / T130A 434 I67T / L70Q / A91G / 1118 V / T 120S 436 L70Q / A91G / T11OA / 1118 V / T 120S / T130A 437 M38V / T41D / M43I / W50G / D76G / V83A / K89E / I118V / T120S / I126V / T130A 438 Al 2V / S15F / Y31H / M38L / T41G / M43L / D90N / T130A / P137L / N149D / N152T 439 I67F / L70R / E88G / A91G / 1118 V / T 120S / T130A 440 E24G / L25P / L70Q / A91G / 1118 V / T 120S / N152T 441 A91G / F92L / F108L / 1118 V / T 120S 442 E88D / K89R / D90K / A91G / F92Y / K93R / N122S / N177S 443 K36G / K37Q / M38I / L40M / F59L / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / E9 9G / T130A / N149S 444 K36G / L40M 445 476,477 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F 92P / K93 V / R94L / 1118 V / Tl 20S / I127T / T130A / K169E 446 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / 1118 V / T 120S / 1127T / T130A 447 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / 1118 V / T 120S / 1127T / T130A / K169E 448 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91 T / F 92P / K93 V / R94L / 1118 V / Tl 20S / T130A / K169E / M174T 449 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / N48D / F59L / E81V / L85R / K 89N / A91T / F92P / K93 V / R94L / 1118 V / T 120S / 1127T / T130A / H188D 450 2023203586 08 Jun 2023 TABLE 1: Exemplary variant CD80 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L 85R / K89N / A91T / F92P / K93 V / R94L / 1118 V / T120S / T130A / K169E / H188D 451 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / I118 V / T 120S / I127T / T130A / E143G / K169E / M174V / H18 8D 452 R29D / I30V / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / I118 V / T 120S / I127T / T130A / H188D 453 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F 92P / K93 V / R94L / 1118 V / Tl 20S / I127T / T130A / H188D 454 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / I118 V / T 120S / I127T / T130A / K169E 455 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / K89N / A91 T / F 92P / K93 V / R94L / 1118 V / Tl 20S / I127T / T130A 456 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L85R / K89N / A91T / F92P / K 93 V / R94L / 1118 V / T 120S / I127T / T130A / K169E / H188D 457 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91 T / F 92P / K93 V / R94L / F108L / 1118 V / T 120S / T130A / K169E / H188D 458 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / 1118 V / T 120S / T130A / N149D / K169E / H188D 459 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K 89N / A91T / F92P / K93 V / R94L / 1118 V / T 120S / T130A / K169E / H188D 460 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91 T / F 92P / K93 V / R94L / 1118 V / Tl 20S / I127T / C128 Y / T130A / H188D 461 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / E99D / T130A 462 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K 89N / A91T / F92P / K93 V / R94L / 1118 V / T 120S / T130A / K169E 463 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / I61N / E81V / L85R / K89N / A 91T / F92P / K93 V / R94F / V104A / 1118 V / T 120S / I126 V / T 130A 464 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91 T / F 92P / K93 V / R94F / 1118 V / T 120S / T130A 465 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / T62S / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / 1118 V / T 120S / T130A / K169E / T175 A 466 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / 1118 V / T 120S / I127T / T130A / L142S / H188D 467 C16S / H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K 89N / A91T / F92P / K93V / R94L / T110A / I118V / H188D 468 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / A91G / 1118 V / T 120S / I127T / T130A / H188D 469 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / D76G / A91G / S103L / Il 18 V / T 120S / 1127T / T130A 470 Y53C / L85R / K89N / A91T / F92P / K93 V / R94L / 1118 V / T 120S / 1127T / T130A / K169E 471 T62S / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / 1118 V / T 120S / T130A / K169E 472 Y53C / L70Q / D90G / T130A / N149D / N152T / H188D 473 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / 1118 V / T 120S / I127T / T130A / H188D 474 H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A 91T / F92P / K93 V / R94L / T130A / N149S 475

[0187] In some embodiments the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 12, 18, 20, 29, 31, 36, 40, 41, 43, 82 2023203586 08 Jun 2023 52, 59, 60, 63, 67, 70, 77, 81, 87, 88, 89, 90, 91, 92, 93, 107, 109, 114, 117, 118, 120, 122, 127, 130, 144, 169, 178 or 199 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from A12T, H18L, V20L, R29H, Y31H, K36G, L40M, T41G, T41I, M43V, E52G, F59L, D60V, N63S, I67T, L70Q, L70R, E77K, E81A, Y87N, E88D, E88G, K89E, K89R, D90K, D90N, A91G, A91S, F92Y, K93R, D107N, P109S, S114T, E117G, I118A, Il 18T, I118V, T120S, I127T, T130A, N144D, K169E, H178R, or T199S. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from A12T, H18L, V20L, R29H, Y31H, K36G, L40M, T41G, T41I, M43V, E52G, F59L, D60V, N63S, I67T, L70Q, L70R, E77K, E81A, Y87N, E88D, E88G, K89E, K89R, D90K, D90N, A91G, A91S, F92Y, K93R, D107N, P109S, S114T, E117G, I118A, I118T, Il 18V, T120S, I127T, T130A, N144D, K169E, H178R, or T199S or conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitutions is A12T / H18L / M43V / F59L / E77K / P109S / I118T, V20L / L70Q / A91S / T120S / T130A, V20L / L70Q / A91S / 1118 V / T120S / T130A, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, T41VA91G, E52G / L70 / A91G / T120S / T130A, E52G / L70Q / A91G / D107N / I118V / T120S / T130A / K169E, D60V / A91G / T120S / T130A, D60V / A91G / 1118 V / T 120S / T130A / K169E, N63S / L70Q / A91G / T120S / T130A, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, L70Q / E81A / A91G / T120S / I127T / T130A, L70Q / E81A / A91G / 1118V / T 120S / I127T / T130A,L70Q / Y87N / A91 G / T 130A, L70Q / A91G, L70Q / A91G / N144D,L70Q / A91G / E117G / T120S / T130A, L70Q / A91G / E117G / I118V / T120S / T130A, L70Q / A91G / I118A / T120S / T130A, L70Q / A91G / 1118A / T120S / T130A / K169E, L70Q / A91 G / T 120S / T130A, L70Q / A91G / 1118V / T 120S / T130A / K169E, L70R / A91 G / T 120S / T130A, L70R / A91G / 1118V / T 120S / T130A / T199S, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R / N122S / N177S, E88D / K89R / D90K / A91G / F92Y / K93R / N122S / N177S. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of CD28 and / or increased selectivity to CD28 compared to a wild-type or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372. 2023203586 08 Jun 2023

[0188] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) that correspond to position(s) 12, 18, 21, 22, 28, 29, 31, 33, 36, 38, 40, 41, 42, 43, 47, 48, 59, 64, 67, 68, 70, 77, 81, 85, 87, 88, 89, 90, 91, 92, 93, 94, 97, 104, 109, 115, 117, 118, 120, 122, 126, 130, 133, 140, 144, 148, 149, 168, 169, 177, 183, 188 or 193. of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of A12G, A12T, H18L, S21P, V22A, T28A, R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, L40M, T41A, T41G, M42T, M43R, M43V, M47T, N48I, F59L, N64S, I67T, V68A, V68M, L70Q, E77K, E81V, L85R, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90N, A91G, A91T, F92P, F92Y, K93R, K93V, R94F, R94L, L97R, V104L, P109H, P109S, D115G, El 17V, Il 18T, Il 18V, T120S, N122S, I126L, T130A, G133D, S140T, N144S, L148S, N149S, S168G, K169I, K169S, N177S, L183H, H188Q, R190S and Q193L. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of A12T, H18L, R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, L40M, T41A, T41G, M42T, M43R, M43V, M47T, F59L, I67T, L70Q, E77K, E81V, L85R, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90N, A91G, A91T, F92P, F92Y, K93R, K93V, R94L, P109S, Il 18T, I118V,T120S, N122S, N144S, L148S, N149S, and N178S, and conservative amino acid substitutions thereof.

[0189] In some embodiments, the one or more amino acid substitutions is A12T / H18L / M43V / F59L / E77K / P109S / I118T, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, A91G, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 2023203586 08 Jun 2023 V / R94L / T130A / N149S / R190S, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / E117V / I118T / N149S / S168G / H188Q, V22A / R29D / Y31L / Q33H / K36G / M38ET41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / I118T / T130A / N149S / K169I, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / D115G / I118T / T130A / G133D / N149S, T28A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / V104L / T130A / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S / H188Q, K89E / T130A, K89E / K93E / T130A, S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / N48VV68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / S21P / N48I / V68A / P109H / I126L / K169I, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S, A12G / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / L97R / T130A / L183H, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / S140T / N149S / K169S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169VQ193L, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169I, or R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 2023203586 08 Jun 2023 F / T130A / N149S / K169I. In some embodiments, the variant CD80 polypeptide exhibits increased affinity to PD-L1 and / or increased selectivity to PD-L1 compared to the wild-type or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0190] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) that correspond to position(s) 12, 18, 36, 40, 43, 59, 77, 88, 89, 90, 91, 92, 93, 109, 118, 122, or 177 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of A12T, H18L, K36G, M43V, F59L, E77K, E88D, K89R, D90K, A91G, F92Y, K93R, P109S, Il 18T, N112S, and N177S. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of A12T, H18L, K36G, L40M, M43V, F59L, E77K, E88D, K89R, D90K, A91G, F92Y, K93R, P109S, Il 18T, N112S, and N177S, and conservative mutations thereof. In some embodiments, the one or more amino acid substitution is A12T / H18L / M43V / F59L / E77K / P109S / I118T, K36G, K36G / L40M, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, E8 8D / K89R / D90K / A91G / F92Y / K93R / N122S / N177S, or K89R / D90K / A91G / F92Y / K93R / N122S / N177S. In some embodiments, the variant CD80 polypeptide exhibits increased affinity to the ectodomain of CD28 and the ectodomain of PD-L1 compared to a wildtype or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0191] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 4, 29, 31, 36, 40, 41, 52, 67, 68, 70,87,88,89,90,91,92,93, 107, 109, 110, 118, 120, 130, 144, or 169 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of V4M, R29H, Y31H, K36G, L40M, T41G, E52G, I67T, V68A, L70Q, Y87N, E88D, E88G, K89E, K89R, D90K, D90N, A91G, F92Y, K93R, D107N, P109S, T110A, Il 18V, T120S, T130A, N144D, and K169E. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of V4M, R29H, Y31H, K36G, L40M, T41I, T41G, E52G, I67T, I69T, V68A, L70Q, Y87N, E88D, E88G, K89E, K89R, D90K, D90N, A91G, F92Y, K93R, D107N, P109S, T110A, Il 18V, T120S, T130A, N144D, and K169E and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is V4M / L70Q / A91G / T120S / T130A, V4M / L70Q / A91G / 1118 V / T120S / T130A / K169E, 2023203586 08 Jun 2023 R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, T41EA91G, E52G / L70Q / A91G / T120S / T130A, E52G / L70Q / A91G / D107N / I118V / T120S / T130A / K169E, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T12OS,V68A / T110A, L70Q / A91G, L70Q / A91G / N144D, L70Q / A91G / T 120S / T130A, L70Q / A91G / 1118V / T120S / T130A / K169E, L70Q / A91G / T130A, K89R / D90K / A91G / F92Y / K93R, E88D / K89R / D90K / A91G / F92Y / K93R, A91G / I118V / T120S / T130A, A91G / T120S / T130A or I69T / L70Q / A91G / T120S. In some embodiments, the variant CD80 polypeptide exhibits increased affinity and / or increased selectivity to the ectodomain of CTLA-4 compared to a wildtype or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372. I In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 36, 40, 52, 70, 88, 89, 90, 91, 92, 93,107, 118120, 130, 144, or 169of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of K36G, L40M, E52G, L70Q, E88D, K89R, D90K, A91G, F92Y, K93R, D107N, Il 18V, T120S, T130A, N144D, and K169E. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of K36G, L40M, E52G, L70Q, E88D, K89R, D90K, A91G, F92Y, K93R, D107N, Il 18V, T120S, T130A N144D, and K169E, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is K36G, K36G / L40M, E52G / L70Q / A91G / T120S / T130A, E52G / L70Q / A91G / D107N / I118V / T120S / T130A / K169E, L70Q / A91G, L70Q / A91G / N144D, L70Q / A91 G / T 120S / T130A, L70Q / A91G / 1118 V / T 120S / T130A / K169E, E88D / K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of CD28 and the ectodomain of CTLA-4 compared to a wildtype or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0192] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 29, 31, 36, 40, 41, 67, 70, 87, 88, 89, 90, 91, 92, 93, 109, 118, 120, 122, 130, or 178 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of R29H, Y31H, K36G, L40M, T41G, I67T, L70Q, Y87N, E88D, E88G, K89E, K89R, D90N, D90K, A91G, F92Y, K93R, P109S, Il 18V, T120S. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group 2023203586 08 Jun 2023 consisting of R29H, Y31H, K36G, L40M, T41G, I67T, L70Q, Y87N, E88D, E88G, K89E, K89R, D90N, D90K, A91G, F92Y, K93R, P109S, Il 18V, T120S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitutions is R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of PD-L1 and the ectodomain of CTLA-4 compared to wild-type or an unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0193] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 36, 40, 88 89, 90, 91, 92, or 93 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of K36G, L40M, E88D, K89R, D90K, A91G, F92Y, and K93R. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of K36G, L40M, E88D, K89R, D90K, A91G, F92Y, K93R, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitutions is K36G, K36G / L40M, E88D / K89R / D90K / A91G / F92Y / K93R, or K89R / D90K / A91G / F92Y / K93R. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of CD28, the ectodomain of PD-L1 and the ectodomain of CTLA-4 compared to wild-type or an unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0194] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 12, 18, 29, 31, 33, 36, 38, 40, 41, 42, 43, 47, 48, 63, 59, 64, 67, 68, 70, 81, 85, 87, 88, 89, 90, 91, 92, 93, 94, 97, 104, 109, 114, 115, 117, 118, 120, 122, 126, 127, 130, 133, 140, 144, 148,149, 168, 169, 177, 183, 188 or 193 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of A12G, A12T, H18L, S21P, V22A, T28A, R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, L0M, T41A, T41G, M42T, M43R, M43V, M47T, N48I, F59L, N63S, N64S, I67T, V68A, V68M, L70Q, E77K, E81A, E81V, L85R, Y87N, E88D, E88G, K89E, K89N, D90K, D90N, A91G, A91T, F92P, F92Y, K93R, K93V, R94F, R94L, L97R, S103L, S103P, V104L, P109H, P109S, D115G, El 17V, Il 18T, S114T, Il 18V, 2023203586 08 Jun 2023 T120S, N122S, I126L, I127T, T130A, G133D, S140T, N144S, L148S, N149S, S168G, K169I, K169S, N177S, L183H, H188Q, R190S and Q193L. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, T41A, T41G, M42T, M43R, M47T, N63S, I67T, L70Q, E81A, E81V, L85R, Y87N, E88G, K89E, K89N, D90N, A91G, A91T, F92P, K93V, R94L, P109S, S114T, Il 18V, Il 18T, T120S, I127T, T130A, N144S, L148S, and N149S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitutions is N63S / L70Q / A91G / T120S / T130A, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, L70Q / Y87N / A91G / T120S / I127T / T130A. In some embodiments, the one or more amino acid substitutions is A12T / H18L / M43V / F59L / E77K / P109S / I118T, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, A91G, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S / R190S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / E117V / I118T / N149S / S168G / H188Q, V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / I118T / T130A / N149S / K169I, V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 2023203586 08 Jun 2023 P / K93 V / R94L / D115 G / 1118T / T130A / G133D / N149S, T28A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / V104L / T130A / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S / H188Q, K89E / T130A, K89E / K93E / T130A, S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / N48VV68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / S21P / N48I / V68A / P109H / I126L / K169I, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S, A12G / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / L97R / T130A / L183H, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / S140T / N149S / K169S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169VQ193L, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169I, or R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / T130A / N149S / K169I. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of CD28 or the ectodomain of PD-L1, and decreased affinity for the ectodomain of CTLA-4, compared to wild-type or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0195] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 63, 70, 81, 87, 91, 114, 118, 120, 127, or 130 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of N63S, L70Q, E81A, Y87N, 2023203586 08 Jun 2023 A91G, S114T, Il 18V, T120S, I127T, and T130A. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of N63S, L70Q, E81A, Y87N, A91G, S114T, I118V, T120S, I127T, and T130A, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29H / Y31H / T41G / Y87N / E8 8G / K89E / D90N / A91G / P109S, N63S / L70Q / A91G / T120S / T130A, N63S / L70Q / A91G / S114T / I118V / T120S / T130A, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, or L70Q / Y87N / A91G / T120S / I127T / T130A. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of CD28, and decreased affinity for the ectodomain of CTLA-4, compared to wild-type or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372.

[0196] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 12, 18, 29, 31, 33, 36, 38, 40, 41, 42, 43, 47, 48, 59, 64, 67, 68, 70, 77, 81, 85, 87, 88, 89, 90, 91, 92, 93, 94, 97, 104, 109, 115, 117, 118, 120, 122, 126, 130, 133, 140, 144, 148, 149, 168, 169, 177, 183, 188 or 193 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of A12G, A12T, H18L, S21P, V22A, T28A, R29D, R29H, Y31H, Y31L, Q33H, K36G, M38I, L40M, T41A, T41G, M42T, M43R, M47T, M43V, N48I, F59L, N64S, I67T, V68A, V68M, L70Q, E77K, E81V, L85R, Y87N, E88D, E88G, K89E, K89N, K89R, D90K, D90N, A91G, A91T, F92P, F92Y, K93V, R94F, R94L, L97R, S103L, S103P, V104L, P109H, P109S, D115G, E117V, Il 18T, I118V, T120S, N122S, I126L, T130A, G133D, S140T, N144S, L148S, N149S, S168G, K169I, K169S, N177S, L183H, H188Q, R190S and Q193L. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of R29D, R29H, Y31H, Y31L, 2023203586 08 Jun 2023 Q33H, K36G, M38I, T41A, T41G, M42T, M43R, M47T, I67T, L70Q, E81V, L85R, Y87N, E88G, K89E, K89N, D90N, A91G, A91T, F92P, K93V, R94L, P109S, Il 18T, Il 18V, T120S, N144S, L148S, and N149S, and conservative amino acid substitutions thereof. In some embodiments, the one or more amino acid substitution is R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29H / Y31H / T41G / Y87N / E8 8G / K89E / D90N / A91G / P109S, I67T / L70Q / A91G / I118V / T120S, or I67T / L70Q / A91G / T120S. In some embodiments, the one or more amino acid substitutions is A12T / H18L / M43V / F59L / E77K / P109S / I118T, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N144S / N149S, R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L148S / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / N149S, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S, K36G, K36G / L40M, I67T / L70Q / A91G / T120S, I67T / L70Q / A91G / I118V / T120S, E88D / K89R / D90K / A91G / F92Y / K93R, K89R / D90K / A91G / F92Y / K93R, A91G, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118V / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S / R190S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / E117V / I118T / N149S / S168G / H188Q, V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, 2023203586 08 Jun 2023 R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93 V / R94F / I118T / T130A / N149S / K169I, V22A / R29D / Y31L / Q33H / K36G / M38FT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93 V / R94L / D115G / I118T / T130A / G133D / N149S, T28A / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / V104L / T130A / N149S, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / L97R / N149S / H188Q, K89E / T130A, K89E / K93E / T130A, S21P / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / N48VV68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / S21P / N48I / V68A / P109H / I126L / K169I, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / V68M / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / T130A, H18L / R29D / Y31L / Q33H / K36G / M38VT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / T130A / N149S, A12G / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92 P / K93V / R94L / L97R / T130A / L183H, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / S140T / N149S / K169S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169VQ193L, V22A / R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93 V / R94L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S, R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 L / I118T / T130A / N149S / K169I, or R29D / Y31L / Q33H / K36G / M38PT41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94 F / T130A / N149S / K169L In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of PD-L1, and decreased affinity for the ectodomain of CTLA-4, compared to wild-type or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372. 2023203586 08 Jun 2023

[0197] In some embodiments, the variant CD80 polypeptide has one or more amino acid modifications (e.g., substitutions) corresponding to position(s) 70, 81, 87, 91, or 120 of SEQ ID NO: 28. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of L70Q, Y87N, A91G, and T120S. In some embodiments, the variant CD80 polypeptide has one or more amino acid substitutions selected from the group consisting of L70Q, Y87N, A91G, and T120S, and conservative amino acid substitutions thereof. In some embodiments, the variant CD80 polypeptide exhibits increased affinity for the ectodomain of CD28 and the ectodomain of PD-L1, and decreased affinity for the ectodomain of CTLA-4, compared to wild-type or unmodified CD80 polypeptide, such as comprising the sequence set forth in SEQ ID NO: 28, 152, or 372. III. FORMAT OF VARIANT POLYPEPTIDES

[0198] The immunomodulatory polypeptide comprising a variant CD80 provided herein in which is contained a vlgD can be formatted in a variety of ways, including as a soluble protein, fusion or conjugate, membrane bound protein, secreted protein or for delivery in an infectious agent. In some embodiments, the particular format can be chosen for the desired therapeutic application. In some cases, an immunomodulatory polypeptide comprising a variant CD80 polypeptide is provided in a format to antagonize or block activity of its cognate binding partner, e.g. CD28, PD-L1 and / or CTLA-4. In some embodiments, antagonism of CTLA-4 may be useful to promote immunity in oncology. In some embodiments, antagonism of CD28 may be useful for treating inflammation or autoimmunity. In some cases, an immunomodulatory polypeptide comprising a variant CD80 polypeptide is provided in a format to agonize or stimulate activity of its cognate binding partner, e.g. CD28, PD-L1 and / or CTLA-4. In some embodiments, agonism of CTLA-4 may be useful for treating inflammation or autoimmunity. In some embodiments, agonism of CD28 may be useful for treating oncology. A skilled artisan can readily determine the activity of a particular format, such as for antagonizing or agonizing one or more specific cognate binding partner. Exemplary methods for assessing such activities are provided herein, including in the examples.

[0199] In some aspects, provided are immunomodulatory proteins comprising a vlgD of CD80 in which such proteins are soluble, e.g. fused to an Fc chain. In some aspects, one or more additional IgSF domain, such as one or more additional vlgD, may be linked to a vlgD of CD80 as provided herein (hereinafter called a “stack” or “stacked” immunomodulatory protein). In some embodiments, the modular format of the provided immunomodulatory proteins provides 2023203586 08 Jun 2023 flexibility for engineering or generating immunomodulatory proteins for modulating activity of multiple counter structures (multiple cognate binding partners). In some embodiments, such “stack” molecules can be provided in a soluble format or, in some cases, may be provided as membrane bound or secreted proteins. In some embodiments, a variant CD80 immunomodulatory protein is provided as a conjugate in which is contained a vlgD of CD80 linked, directly or indirectly, to a targeting agent or moiety, e.g. to an antibody or other binding molecules that specifically binds to a ligand, e.g. an antigen, for example, for targeting or localizing the vlgD to a specific environment or cell, such as when administered to a subject. In some embodiments, the targeting agent, e.g. antibody or other binding molecule, binds to a tumor antigen, thereby localizing the variant CD80 containing the vlgD to the tumor microenvironment, for example, to modulate activity of tumor infiltrating lymphocytes (TILs) specific to the tumor microenvironment.

[0200] In some embodiments, provided immunomodulatory proteins are expressed in cells and provided as part of an engineered cellular therapy (ECT). In some embodiments, the variant CD80 polypeptide is expressed in a cell, such as an immune cell (e.g. T cell or antigen presenting cell), in membrane-bound form, thereby providing a transmembrane immunomodulatory protein (hereinafter also called a “TIP”). In some embodiments, depending on the cognate binding partner recognized by the TIP, engineered cells expressing a TIP can agonize a cognate binding partner by providing a costimulatory signal, either positive to negative, to other engineered cells and / or to endogenous T cells. In some aspects, the variant CD80 polypeptide is expressed in a cell, such as an immune cell (e.g. T cell or antigen presenting cell), in secretable form to thereby produce a secreted or soluble form of the variant CD80 polypeptide (hereinafter also called a “SIP”), such as when the cells are administered to a subject. In some aspects, a SIP can antagonize a cognate binding partner in the environment (e.g. tumor microenvironment) in which it is secreted. In some embodiments, a variant CD80 polypeptide is expressed in an infectious agent (e.g. viral or bacterial agent) which, upon administration to a subject, is able to infect a cell in vivo, such as an immune cell (e.g. T cell or antigen presenting cell), for delivery or expression of the variant polypeptide as a TIP or a SIP in the cell.

[0201] In some embodiments, a soluble immunomodulatory polypeptide, such as a variant CD80 containing a vlgD, can be encapsulated within a liposome which itself can be conjugated to any one of or any combination of the provided conjugates (e.g., a targeting moiety). In some embodiments, the soluble or membrane bound immunomodulatory polypeptides of the invention 2023203586 08 Jun 2023 are deglycosylated. In more specific embodiments, the variant CD80 sequence is deglycosylated. In even more specific embodiments, the IgV and / or IgC (e.g. IgC2) domain or domains of the variant CD80 is deglycosylated.

[0202] Non-limiting examples of provided formats are described in FIGS. 1A-1C and further described below. A. Soluble Protein

[0203] In some embodiments, the immunomodulatory protein containing a variant CD80 polypeptide is a soluble protein. Those of skill will appreciate that cell surface proteins typically have an intracellular, transmembrane, and extracellular domain (ECD) and that a soluble form of such proteins can be made using the extracellular domain or an immunologically active subsequence thereof. Thus, in some embodiments, the immunomodulatory protein containing a variant CD80 polypeptide lacks a transmembrane domain or a portion of the transmembrane domain. In some embodiments, the immunomodulatory protein containing a variant CD80 lacks the intracellular (cytoplasmic) domain or a portion of the intracellular domain. In some embodiments, the immunomodulatory protein containing the variant CD80 polypeptide only contains the vlgD portion containing the ECD domain or a portion thereof containing an IgV domain and / or IgC (e.g. IgC2) domain or domains or specific binding fragments thereof containing the amino acid modification(s).

[0204] In some embodiments, an immunomodulatory polypeptide comprising a variant CD80 can include one or more variant CD80 polypeptides of the invention. In some embodiments a polypeptide of the invention will comprise exactly 1, 2, 3, 4, 5 variant CD80 sequences. In some embodiments, at least two of the variant CD80 sequences are identical variant CD80 sequences.

[0205] In some embodiments, the provided immunomodulatory polypeptide comprises two or more vlgD sequences of CD80. Multiple variant CD80 polypeptides within the polypeptide chain can be identical (i.e., the same species) to each other or be non-identical (i.e., different species) variant CD80 sequences. In addition to single polypeptide chain embodiments, in some embodiments two, three, four, or more of the polypeptides of the invention can be covalently or non-covalently attached to each other. Thus, monomeric, dimeric, and higher order (e.g., 3, 4, 5, or more) multimeric proteins are provided herein. For example, in some embodiments exactly two polypeptides of the invention can be covalently or non-covalently attached to each other to form a dimer. In some embodiments, attachment is made via interchain cysteine disulfide bonds. 96 2023203586 08 Jun 2023 Compositions comprising two or more polypeptides of the invention can be of an identical species or substantially identical species of polypeptide (e.g, a homodimer) or of non-identical species of polypeptides (e.g., a heterodimer). A composition having a plurality of linked polypeptides of the invention can, as noted above, have one or more identical or non-identical variant CD80 polypeptides of the invention in each polypeptide chain.

[0206] In some embodiments, the immunomodulatory protein comprises a variant CD80 polypeptide attached to an immunoglobulin Fc (yielding an “immunomodulatory Fc fusion,” such as a “variant CD80-Fc fusion,” also termed a CD80 vlgD-Fc fusion). In some embodiments, the attachment of the variant CD80 polypeptide is at the N-terminus of the Fc. In some embodiments, the attachment of the variant CD80 polypeptide is at the C-terminus of the Fc. In some embodiments, two or more CD80 variant polypeptides (the same or different) are independently attached at the N-terminus and at the C-terminus.

[0207] In some embodiments, the Fc is murine or human Fc. In some embodiments, the Fc is a mammalian or human IgGl, lgG2, lgG3, or lgG4 Fc regions. In some embodiments, the Fc is derived from IgGl, such as human IgGl. In some embodiments, the Fc comprises the amino acid sequence set forth in SEQ ID NO: 226 or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 226.

[0208] In some embodiments, the Fc region contains one more modifications to alter (e.g. reduce) one or more of its normal functions. In general, the Fc region is responsible for effector functions, such as complement-dependent cytotoxicity (CDC) and antibody-dependent cell cytotoxicity (ADCC), in addition to the antigen-binding capacity, which is the main function of immunoglobulins. Additionally, the FcRn sequence present in the Fc region plays the role of regulating the IgG level in serum by increasing the in vivo half-life by binding to an in vivo FcRn receptor. In some embodiments, such functions can be reduced or altered in an Fc for use with the provided Fc fusion proteins.

[0209] In some embodiments, one or more amino acid modifications may be introduced into the Fc region of a CD80-Fc variant fusion provided herein, thereby generating an Fc region variant. In some embodiments, the Fc region variant has decreased effector function. There are many examples of changes or mutations to Fc sequences that can alter effector function. For example, WO 00 / 42072, WO2006019447, WO2012125850, WO2015 / 107026, US2016 / 0017041 and Shields et al. J Biol. Chem. 9(2): 6591-6604 (2001) describe exemplary Fc variants with 2023203586 08 Jun 2023 improved or diminished binding to FcRs. The contents of those publications are specifically incorporated herein by reference.

[0210] In some embodiments, the provided variant CD80-Fc fusions comprise an Fc region that exhibits reduced effector functions, which makes it a desirable candidate for applications in which the half-life of the CD80-Fc variant fusion in vivo is important yet certain effector functions (such as CDC and ADCC) are unnecessary or deleterious. In vitro and / or in vivo cytotoxicity assays can be conducted to confirm the reduction / depletion of CDC and / or ADCC activities. For example, Fc receptor (FcR) binding assays can be conducted to ensure that the CD80-Fc variant fusion lacks FcyR binding (hence likely lacking ADCC activity), but retains FcRn binding ability. The primary cells for mediating ADCC, NK cells, express FcyRIII only, whereas monocytes express FcyRI, FcyRII and FcyRIII. FcR expression on hematopoietic cells is summarized in Table 3 on page 464 of Ravetch and Kinet, Annu. Rev. Immunol. 9:457-492 (1991). Non-limiting examples of in vitro assays to assess ADCC activity of a molecule of interest is described in U.S. Pat. No. 5,500,362 (see, e.g. Hellstrom, I. et al. Proc. Nat'l Acad. Sci. USA 83:7059-7063 (1986)) and Hellstrom, I et al.. Proc. Nat'l Acad. Sci. USA 82:1499-1502 (1985); U.S. Pat. No. 5,821,337 (see Bruggemann, M. et al., J. Exp. Med. 166:1351-1361 (1987)). Alternatively, non-radioactive assay methods may be employed (see, for example, ACTI™ non-radioactive cytotoxicity assay for flow cytometry (CellTechnology, Inc. Mountain View, Calif.; and CytoTox 96™ non-radioactive cytotoxicity assay (Promega, Madison, Wis.). Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e.g., in an animal model such as that disclosed in Clynes et al. Proc. Nat'l Acad. Sci. USA 95:652-656 (1998). Clq binding assays may also be carried out to confirm that the CD80-Fc variant fusion is unable to bind Clq and hence lacks CDC activity. See, e.g., Clq and C3c binding ELISA in WO 2006 / 029879 and WO 2005 / 100402. To assess complement activation, a CDC assay may be performed (see, for example, Gazzano-Santoro et al., J. Immunol. Methods 202:163 (1996); Cragg, M. S. et al., Blood 101:1045-1052 (2003); and Cragg, M. S. and M. J. Glennie, Blood 103:2738-2743 (2004)). FcRn binding and in vivo clearance / half life determinations can also be performed using methods known in the art (see, e.g., Petkova, S. B. et al., Int'l. Immunol. 18(12):1759-1769 (2006)). 2023203586 08 Jun 2023

[0211] CD80-Fc variant fusions with reduced effector function include those with substitution of one or more of Fc region residues 238, 265, 269, 270, 297, 327 and 329 by EU numbering (U.S. Pat. No. 6,737,056). Such Fc mutants include Fc mutants with substitutions at two or more of amino acid positions 265, 269, 270, 297 and 327 by EU numbering, including the so-called “DANA” Fc mutant with substitution of residues 265 and 297 to alanine (U.S. Pat. No. 7,332,581).

[0212] In some embodiments, the Fc region of CD80-Fv variant fusions has an Fc region in which any one or more of amino acids at positions 234, 235, 236, 237, 238, 239, 270, 297, 298, 325, and 329 (indicated by EU numbering) are substituted with different amino acids compared to the native Fc region. Such alterations of Fc region are not limited to the above-described alterations, and include, for example, alterations such as deglycosylated chains (N297A and N297Q), IgGl-N297G, IgGl-L234A / L235A, IgGl-L234A / L235E / G237A, IgGl-A325A / A330S / P331S, IgGl-C226S / C229S, IgGl-C226S / C229S / E233P / L234V / L235A, IgGl-E233P / L234V / L235A / G236del / S267K, IgGl-L234F / L235E / P331S, IgGl-S267E / L328F, IgG2-V234A / G237A, IgG2-H268Q / V309L / A330S / A331S, IgG4-L235A / G237A / E318A, and IgG4-L236E described in Current Opinion in Biotechnology (2009) 20 (6), 685-691; alterations such as G236R / L328R, L235G / G236R, N325A / L328R, and N325LL328R described in WO 2008 / 092117; amino acid insertions at positions 233, 234, 235, and 237 (indicated by EU numbering); and alterations at the sites described in WO 2000 / 042072.

[0213] Certain Fc variants with improved or diminished binding to FcRs are described. (See, e.g., U.S. Pat. No. 6,737,056; WO 2004 / 056312, WO2006019447 and Shields et al., J. Biol. Chem. 9(2): 6591-6604 (2001).)

[0214] In some embodiments, there is provided a CD80-Fc variant fusion comprising a variant Fc region comprising one or more amino acid substitutions which increase half-life and / or improve binding to the neonatal Fc receptor (FcRn). Antibodies with increased half-lives and improved binding to FcRn are described in US2005 / 0014934A1 (Hinton et al.) or WO2015107026. Those antibodies comprise an Fc region with one or more substitutions therein which improve binding of the Fc region to FcRn. Such Fc variants include those with substitutions at one or more of Fc region residues: 238, 256, 265, 272, 286, 303, 305, 307, 311, 312, 317, 340, 356, 360, 362, 376, 378, 380, 382, 413, 424 or 434 by EU numbering, e.g., substitution of Fc region residue 434 (U.S. Pat. No. 7,371,826). 2023203586 08 Jun 2023

[0215] In some embodiments, the Fc region of a CD80-Fc variant fusion comprises one or more amino acid substitution E356D and M358L. In some embodiments, the Fc region of a CD80-Fc variant fusion comprises one or more amino acid substitutions C220S, C226S, C229S. In some embodiments, the Fc region of a CD80 variant fusion comprises one or more amino acid substitutions R292C and V302C. See also Duncan & Winter, Nature 322:738-40 (1988); U.S. Pat. No. 5,648,260; U.S. Pat. No. 5,624,821; and WO 94 / 29351 concerning other examples of Fc region variants.

[0216] In some embodiments, alterations are made in the Fc region that result in diminished Clq binding and / or Complement Dependent Cytotoxicity (CDC), e.g., as described in U.S. Pat. No. 6,194,551, WO 99 / 51642, and Idusogie et al., J. Immunol. 164: 4178-4184 (2000).

[0217] In some embodiments, there is provided a CD80-Fc variant fusion comprising a variant Fc region comprising one or more amino acid modifications, wherein the variant Fc region is derived from IgGl, such as human IgGl. In some embodiments, the variant Fc region is derived from the amino acid sequence set forth in SEQ ID NO: 226. In some embodiments, the Fc contains at least one amino acid substitution that is N82G by numbering of SEQ ID NO: 226 (corresponding to N297G by EU numbering). In some embodiments, the Fc further contains at least one amino acid substitution that is R77C or V87C by numbering of SEQ ID NO: 226 (corresponding to R292C or V302C by EU numbering). In some embodiments, the variant Fc region further comprises a C5S amino acid modification by numbering of SEQ ID NO: 226 (corresponding to C220S by EU numbering). For example, in some embodiments, the variant Fc region comprises the following amino acid modifications: N82G and one or more of the following amino acid modifications C5S, R77C or V87C with reference to SEQ ID NO:226.

[0218] In some embodiments, there is provided a CD80-Fc variant fusion comprising a variant Fc region in which the variant Fc comprises the sequence of amino acids set forth in any of SEQ ID NOS:389, 392-394 and 413, or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOS: 389, 392-394 and 413.

[0219] In some embodiments, the Fc is derived from IgG2, such as human IgG2. In some embodiments, the Fc comprises the amino acid sequence set forth in SEQ ID NO: 227 or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 227. 2023203586 08 Jun 2023

[0220] In some embodiments, the Fc comprises the amino acid sequence set forth in SEQ ID NO: 411 or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 411. In some embodiments, the IgG4 Fc is a stabilized Fc in which the CH3 domain of human IgG4 is substituted with the CH3 domain of human IgGl and which exhibits inhibited aggregate formation, an antibody in which the CH3 and CH2 domains of human IgG4 are substituted with the CH3 and CH2 domains of human IgGl, respectively, or an antibody in which arginine at position 409 indicated in the EU index proposed by Kabat et al. of human IgG4 is substituted with lysine and which exhibits inhibited aggregate formation (see e.g. U.S. Patent No. 8,911,726). In some embodiments, the Fc is an IgG4 containing the S228P mutation, which has been shown to prevent recombination between a therapeutic antibody and an endogenous IgG4 by Fab-arm exchange (see e.g. Labrijin et al. (2009) Nat. Biotechnol., 27(8)767-71.) In some embodiments, the Fc comprises the amino acid sequence set forth in SEQ ID NO: 412 or a sequence of amino acids that exhibits at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 412.

[0221] In some embodiments, the variant CD80 polypeptide is directly linked to the Fc sequence. In some embodiments, the variant CD80 polypeptide is indirectly linked to the Fc sequence, such as via a linker. In some embodiments, one or more “peptide linkers” link the variant CD80 polypeptide and the Fc domain. In some embodiments, a peptide linker can be a single amino acid residue or greater in length. In some embodiments, the peptide linker has at least one amino acid residue but is no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid residues in length. In some embodiments, the linker is (in one-letter amino acid code): GGGGS (“4GS”) or multimers of the 4GS linker, such as repeats of 2, 3, 4, or 5 4GS linkers.

[0222] In some embodiments, the variant CD80-Fc fusion protein is a dimer formed by two variant CD80 Fc polypeptides linked to an Fc domain. In some specific embodiments, identical or substantially identical species (allowing for 3 or fewer N-terminus or C-terminus amino acid sequence differences) of CD80-Fc variant fusion polypeptides will be dimerized to create a homodimer. In some embodiments, the dimer is a homodimer in which the two variant CD80 Fc polypeptides are the same. Alternatively, different species of CD80-Fc variant fusion polypeptides can be dimerized to yield a heterodimer. Thus, in some embodiments, the dimer is a heterodimer in which the two variant CD80 Fc polypeptides are different. 2023203586 08 Jun 2023

[0223] Also provided are nucleic acid molecules encoding the variant CD80-Fc fusion protein. In some embodiments, for production of an Fc fusion protein, a nucleic acid molecule encoding a variant CD80-Fc fusion protein is inserted into an appropriate expression vector. The resulting variant CD80-Fc fusion protein can be expressed in host cells transformed with the expression where assembly between Fc domains occurs by interchain disulfide bonds formed between the Fc moieties to yield dimeric, such as divalent, variant CD80-Fc fusion proteins.

[0224] The resulting Fc fusion proteins can be easily purified by affinity chromatography over Protein A or Protein G columns. For the generation of heterodimers, additional steps for purification can be necessary. For example, where two nucleic acids encoding different variant CD80 polypeptides are transformed into cells, the formation of heterodimers must be biochemically achieved since variant CD80 molecules carrying the Fc-domain will be expressed as disulfide-linked homodimers as well. Thus, homodimers can be reduced under conditions that favor the disruption of interchain disulfides, but do no effect intra-chain disulfides. In some cases, different variant-CD80 Fc monomers are mixed in equimolar amounts and oxidized to form a mixture of homo- and heterodimers. The components of this mixture are separated by chromatographic techniques. Alternatively, the formation of this type of heterodimer can be biased by genetically engineering and expressing Fc fusion molecules that contain a variant CD80 polypeptide using knob-into-hole methods described below. B. Stack Molecules with Additional IgSF Domains

[0225] In some embodiments, the immunomodulatory proteins can contain any of the variant CD80 polypeptides provided herein linked, directly or indirectly, to one or more other immunoglobulin superfamily (IgSF) domain (“stacked” immunomodulatory protein construct and also called a “Type II” immunomodulatory protein). In some aspects, this can create unique multi-domain immunomodulatory proteins that bind two or more, such as three or more, cognate binding partners, thereby providing a multi-targeting modulation of the immune synapse.

[0226] In some embodiments, an immunomodulatory protein comprises a combination (a “non-wild-type combination”) and / or arrangement (a “non-wild type arrangement” or “non-wildtype permutation”) of a variant CD80 domain with one or more other affinity modified and / or non-affinity modified IgSF domain sequences of another IgSF family member (e.g. a mammalian IgSF family member) that are not found in wild-type IgSF family members. In some embodiments, the immunomodulatory protein contains 2, 3, 4, 5 or 6 immunoglobulin 2023203586 08 Jun 2023 superfamily (IgSF) domains, where at least one of the IgSF domain is a variant CD80 IgSF domain (vlgD of CD80) according to the provided description.

[0227] In some embodiments, the sequences of the additional IgSF domains can be a modified IgSF domain that contains one or more amino acid modifications, e.g. substitutions, compared to a wildtype or unmodified IgSF domain. In some embodiments, the IgSF domain can be non-affinity modified (e.g., wild-type) or have been affinity modified. In some embodiments, the unmodified or wild-type IgSF domain can be from mouse, rat, cynomolgus monkey, or human origin, or combinations thereof. In some embodiments, the additional IgSF domains can be an IgSF domain of an IgSF family member set forth in Table 2. In some embodiments, the additional IgSF domain can be an affinity-modified IgSF domain containing one or more amino acid modifications, e.g. substitutions, compared to an IgSF domain contained in an IgSF family member set forth in Table 2.

[0228] In some embodiments, the additional IgSF domain is an affinity or non-affinity modified IgSF domain contained in an IgSF family member of a family selected from Signal-Regulatory Protein (SIRP) Family, Triggering Receptor Expressed On Myeloid Cells Like (TREML) Family, Carcinoembryonic Antigen-related Cell Adhesion Molecule (CEACAM) Family, Sialic Acid Binding Ig-Like Lectin (SIGLEC) Family, Butyrophilin Family, B7 family, CD28 family, V-set and Immunoglobulin Domain Containing (VSIG) family, V-set transmembrane Domain (VSTM) family, Major Histocompatibility Complex (MHC) family, Signaling lymphocytic activation molecule (SLAM) family, Leukocyte immunoglobulin-like receptor (LIR), Nectin (Nec) family, Nectin-like (NECL) family, Poliovirus receptor related (PVR) family, Natural cytotoxicity triggering receptor (NCR) family, T cell immunoglobulin and mucin (TIM) family or Killer-cell immunoglobulin-like receptors (KIR) family. In some embodiments, the additional IgSF domains are independently derived from an IgSF protein selected from the group consisting of CD80(B7-l), CD86(B7-2), CD274 (PD-L1, B7-H1), PDCD1LG2(PD-L2, CD273), ICOSLG(B7RP1, CD275, ICOSL, B7-H2), CD276(B7-H3), VTCN1(B7-H4), CD28, CTLA-4, PDCDl(PD-l), ICOS, BTLA(CD272), CD4, CD8A(CD8-alpha), CD8B(CD8-beta), LAG3, HAVCR2(TIM-3), CEACAM1, TIGIT, PVR(CD155), PVRL2(CD112), CD226, CD2, CD160, CD200, CD200Rl(CD200R), and NC R3 (NKp30).

[0229] The first column of Table 2 provides the name and, optionally, the name of some possible synonyms for that particular IgSF member. The second column provides the protein identifier of the UniProtKB database, a publicly available database accessible via the internet at 2023203586 08 Jun 2023 uniprot.org or, in some cases, the GenBank Number. The Universal Protein Resource (UniProt) is a comprehensive resource for protein sequence and annotation data. The UniProt databases include the UniProt Knowledgebase (UniProtKB). UniProt is a collaboration between the European Bioinformatics Institute (EMBL-EBI), the SIB Swiss Institute of Bioinformatics and the Protein Information Resource (PIR) and supported mainly by a grant from the U.S. National Institutes of Health (NIH). GenBank is the NIH genetic sequence database, an annotated collection of all publicly available DNA sequences (Nucleic Acids Research, 2013 Jan;41(Dl):D36-42). The third column provides the region where the indicated IgSF domain is located. The region is specified as a range where the domain is inclusive of the residues defining the range. Column 3 also indicates the IgSF domain class for the specified IgSF region. Colum 4 provides the region where the indicated additional domains are located (signal peptide, S; extracellular domain, E; transmembrane domain, T; cytoplasmic domain, C). It is understood that description of domains can vary depending on the methods used to identify or classify the domain, and may be identified differently from different sources. The description of residues corresponding to a domain in Table 2 is for exemplification only and can be several amino acids (such as one, two, three or four) longer or shorter. Column 5 indicates for some of the listed IgSF members, some of its cognate cell surface binding partners. TABLE 2. IgSF members according to the present disclosure. IgSF Member (Synonym ) UniProtKB Protein Identifier IgSF Region & Domain Class Other Domains Cognate Cell Surface Binding Partners IgSF Member Amino Acid Sequence (SEQ ID NO) Precursor (mature residues) Mature ECD CD80 (B7-1) NP_005182. 1 P33681 35-135, 35138, 37-138, or 35-141 IgV, 145-230 or 154-232 IgC S: 1-34, E: 35-242, T: 243-263, C: 264-288 CD28, CTLA-4, PD-L1 SEQ ID NO: 1 (35-288) SEQ ID NO: 253 SEQ ID NO: 28 CD86 (B7-2) P42081.2 33-131 IgV, 150-225 IgC2 S: 1-23, E: 24-247, T: 248-268, C: 269-329 CD28, CTLA-4 SEQ ID NO: 2 (24-329) SEQ ID NO: 254 SEQ ID NO: 29 CD274 (PD-L1, B7-H1) Q9NZQ7.1 24-130 IgV, 133-225 IgC2 S: 1-18, E: 19-238, T: 239-259, C: 260-290 PD-1, B7-1 SEQ ID NO: 3 (19-290) SEQ ID NO: 255 SEQ ID NO: 30 PDCD1LG 2 (PD-L2, CD273) Q9BQ51.2 21-118 IgV, 122-203 IgC2 S: 1-19, E: 20-220, T: 221-241, C: 242-273 PD-1, RGMb SEQ ID NO: 4 (20-273) SEQ ID NO: 256 SEQ ID NO: 31 2023203586 08 Jun 2023 TABLE 2. IgSF members according to the present disclosure. IgSF Member (Synonym ) UniProtKB Protein Identifier IgSF Region & Domain Class Other Domains Cognate Cell Surface Binding Partners IgSF Member Amino Acid Sequence (SEQ ID NO) Precursor (mature residues) Mature ECD ICOSLG (B7RP1, CD275, ICOSL, B7-H2) 075144.2 19-129 IgV, 141-227 IgC2 S: 1-18, E: 19-256, T: 257-277, C: 278-302 ICOS, CD28, CTLA-4 SEQ ID NO: 5 (19-302) SEQ ID NO: 257 SEQ ID NO: 32 CD276 (B7-H3) Q5ZPR3.1 29-139 IgV, 145-238 IgC2, 243-357 IgV, 367-453 IgC S: 1-28, E: 29-466, T: 467-487, C: 488-534 SEQ ID NO: 6 (29-534) SEQ ID NO: 258 SEQ ID NO: 33 VTCN1 (B7-H4) Q7Z7D3.1 35-146 IgV, 153-241 IgV S: 1-24, E: 25-259, T: 260-280, C: 281-282 SEQ ID NO: 7 (25-282) SEQ ID NO: 259 SEQ ID NO: 34 CD28 P10747.1 28-137 IgV S: 1-18, E: 19-152, T: 153-179, C: 180-220 B7-1, B7-2, B7RP1 SEQ ID NO: 8 (19-220) SEQ ID NO: 260 SEQ ID NO: 35 CTLA-4 P16410.3 39-140 IgV S: 1-35, E: 36-161, T: 162-182, C: 183-223 B7-1, B7-2, B7RP1 SEQ ID NO: 9 (36-223) SEQ ID NO: 261 SEQ ID NO: 36 PDCD1 (PD-1) Q15116.3 35-145 IgV S: 1-20, E: 21-170, T: 171-191, C: 192-288 PD-L1, PD-L2 SEQ ID NO: 10 (21-288) SEQ ID NO: 262 SEQ ID NO: 37 ICOS Q9Y6W8.1 30-132 IgV S: 1-20, E: 21-140, T: 141-161, C: 162-199 B7RP1 SEQ ID NO: 11 (21-199) SEQ ID NO: 263 SEQ ID NO: 38 BTLA (CD272) Q7Z6A9.3 31-132 IgV S: 1-30, E: 31-157, T: 158-178, C: 179-289 HVEM SEQ ID NO: 12 (31-289) SEQ ID NO: 264 SEQ ID NO: 39 CD4 P01730.1 26-125 IgV, 126-203 IgC2, 204-317 IgC2, 317-389 IgC2 S: 1-25, E: 26-396, T: 397-418, C: 419-458 MHC class II SEQ ID NO: 13 (26-458) SEQ ID NO: 265 SEQ ID NO: 40 CD8A (CD8-alpha) P01732.1 22-135 IgV S: 1-21, E: 22-182, T: 183-203, C: 204-235 MHC class I SEQ ID NO: 14 (22-235) SEQ ID NO: 266 SEQ ID NO: 41 CD8B (CD8-beta) P10966.1 22-132 IgV S: 1-21, E: 22-170, T: 171-191, C: 192-210 MHC class I SEQ ID NO: 15 (22-210) SEQ ID NO: 267 SEQ ID NO: 42 2023203586 08 Jun 2023 TABLE 2. IgSF members according to the present disclosure. IgSF Member (Synonym ) UniProtKB Protein Identifier IgSF Region & Domain Class Other Domains Cognate Cell Surface Binding Partners IgSF Member Amino Acid Sequence (SEQ ID NO) Precursor (mature residues) Mature ECD LAG3 P18627.5 37-167 IgV, 168-252 IgC2, 265-343 IgC2, 349-419 IgC2 S: 1-28, E: 29-450, T: 451-471, C: 472-525 MHC class II SEQ ID NO: 16 (29-525) SEQ ID NO: 268 SEQ ID NO: 43 HAVCR2 (TIM-3) Q8TDQ0.3 22-124 IgV S: 1-21, E: 22-202, T: 203-223, C: 224-301 CEACAM-1, phosphatidylseri ne, Galectin-9, HMGB1 SEQ ID NO: 17 (22-301) SEQ ID NO: 269 SEQ ID NO: 44 CEACAM 1 P13688.2 35-142 IgV, 145-232 IgC2, 237-317 IgC2, 323-413 IgC S: 1-34, E: 35-428, T: 429-452, C: 453-526 TIM-3 SEQ ID NO: 18 (35-526) SEQ ID NO: 270 SEQ ID NO: 45 TIGIT Q495A1.1 22-124 IgV S: 1-21, E: 22-141, T: 142-162, C: 163-244 CD155, CD112 SEQ ID NO: 19 (22-244) SEQ ID NO: 271 SEQ ID NO: 46 PVR (CD 155) P15151.2 24-139 IgV, 145-237 IgC2, 244-328 IgC2 S: 1-20, E: 21-343, T: 344-367, C: 368-417 TIGIT, CD226, CD96, poliovirus SEQ ID NO: 20 (21-417) SEQ ID NO: 272 SEQ ID NO: 47 PVRL2 (CD 112) Q92692.1 32-156 IgV, 162-256 IgC2, 261-345 IgC2 S: 1-31, E: 32-360, T: 361-381, C: 382-538 TIGIT, CD226, CD112R SEQ ID NO: 21 (32-538) SEQ ID NO: 273 SEQ ID NO: 48 CD226 Q15762.2 19-126 IgC2, 135-239 IgC2 S: 1-18, E: 19-254, T: 255-275, C: 276-336 CD155, CD112 SEQ ID NO: 22 (19-336) SEQ ID NO: 274 SEQ ID NO: 49 CD2 P06729.2 25-128 IgV, 129-209 IgC2 S: 1-24, E: 25-209, T: 210-235, C: 236-351 CD58 SEQ ID NO: 23 (25-351) SEQ ID NO: 275 SEQ ID NO: 50 CD 160 095971.1 27-122 IgV S: 1-26 E: 27-122 HVEM, MHC family of proteins SEQ ID NO: 24 (27-159) SEQ ID NO: 276 SEQ ID NO: 51 CD200 P41217.4 31-141 IgV, 142-232 IgC2 S: 1-30, E: 31-232, T: 233-259, C: 260-278 CD200R SEQ ID NO: 25 (31-278) SEQ ID NO: 277 SEQ ID NO: 52 CD200R1 (CD200R) Q8TD46.2 53-139 IgV, 140-228 IgC2 S: 1-28, E: 29-243, T: 244-264, C: 265-325 CD200 SEQ ID NO: 26 (29-325) SEQ ID NO: 278 SEQ ID NO: 53 2023203586 08 Jun 2023 TABLE 2. IgSF members according to the present disclosure. IgSF Member (Synonym ) UniProtKB Protein Identifier IgSF Region & Domain Class Other Domains Cognate Cell Surface Binding Partners IgSF Member Amino Acid Sequence (SEQ ID NO) Precursor (mature residues) Mature ECD NCR3 (NKp30) 014931.1 19-126 IgC-like S: 1-18, E: 19-135, T: 136-156, C: 157-201 B7-H6 SEQ ID NO:27 (19-201) SEQ ID NO: 279 SEQ ID NO: 54 VSIG8 Q5VU13 22-141 IgV 1 146-257 IgV 2 S: 1-21 E: 22-263 T: 264-284 C: 285-414 VISTA SEQ ID NO: 348 (22-414) SEQ ID NO: 349 SEQ ID NO: 350

[0230] The number of such non-affinity modified or affinity modified IgSF domains present in a “stacked” immunomodulatory protein construct (whether non-wild type combinations or non-wild type arrangements) is at least 2, 3, 4, or 5 and in some embodiments exactly 2, 3, 4, or 5 IgSF domains (whereby determination of the number of affinity modified IgSF domains disregards any non-specific binding fractional sequences thereof and / or substantially immunologically inactive fractional sequences thereof).

[0231] In some embodiments of a stacked immunomodulatory protein provided herein, the number of IgSF domains is at least 2 wherein the number of affinity modified and the number of non-affinity modified IgSF domains is each independently at least: 0, 1, 2, 3, 4, 5, or 6. Thus, the number of affinity modified IgSF domains and the number of non-affinity modified IgSF domains, respectively, (affinity modified IgSF domain: non-affinity modified IgSF domain), can be exactly or at least: 2:0 (affinity modified: wild-type), 0:2, 2:1, 1:2, 2:2, 2:3, 3:2, 2:4, 4:2, 1:1, 1:3,3:1, 1:4,4:1, 1:5, or 5:1.

[0232] In some embodiments of a stacked immunomodulatory protein, at least two of the non-affinity modified and / or affinity modified IgSF domains are identical IgSF domains.

[0233] In some embodiments, a stacked immunomodulatory protein provided herein comprises at least two affinity modified and / or non-affinity modified IgSF domains from a single IgSF member but in a non-wild-type arrangement (alternatively, “permutation”). One illustrative example of a non-wild type arrangement or permutation is an immunomodulatory protein comprising a non-wild-type order of affinity modified and / or non-affinity modified IgSF domain sequences relative to those found in the wild-type CD80 whose IgSF domain sequences served as the source of the variant IgSF domains as provided herein. Thus, in one example, the 2023203586 08 Jun 2023 immunomodulatory protein can comprise an IgV proximal and an IgC distal to the transmembrane domain albeit in a non-affinity modified and / or affinity modified form. The presence, in an immunomodulatory protein provided herein, of both non-wild-type combinations and non-wild-type arrangements of non-affinity modified and / or affinity modified IgSF domains, is also within the scope of the provided subject matter.

[0234] In some embodiments of a stacked immunomodulatory protein, the non-affinity modified and / or affinity modified IgSF domains are non-identical (i.e., different) IgSF domains. Non-identical affinity modified IgSF domains specifically bind, under specific binding conditions, different cognate binding partners and are “non-identical” irrespective of whether or not the wild-type or unmodified IgSF domains from which they are engineered was the same. Thus, for example, a non-wild-type combination of at least two non-identical IgSF domains in an immunomodulatory protein can comprise at least one IgSF domain sequence whose origin is from and unique to one CD80, and at least one of a second IgSF domain sequence whose origin is from and unique to another IgSF family member that is not CD80, wherein the IgSF domains of the immunomodulatory protein are in non-affinity modified and / or affinity modified form. However, in alternative embodiments, the two non-identical IgSF domains originate from the same IgSF domain sequence but at least one is affinity modified such that they specifically bind to different cognate binding partners.

[0235] In some embodiments, the provided immunomodulatory proteins, in addition to containing a variant CD80 polypeptide, also contains at least 2, 3, 4, 5 or 6 additional immunoglobulin superfamily (IgSF) domains, such as an IgD domain of an IgSF family member set forth in Table 2. In some embodiments, the provided immunomodulatory proteins contains at least one additional IgSF domain (e.g. a second IgSF domain) in which at least one additional or second IgSF domain is an IgSF domain set forth in a wild-type or unmodified IgSF domain or a specific binding fragment thereof contained in the sequence of amino acids set forth in any of SEQ ID NOS: 1-27 and 348. In some embodiments, the wild-type or unmodified IgSF domain is an IgV domain or an IgC domain, such as an IgCl or IgC2 domain.

[0236] In some embodiments, the provided immunomodulatory proteins, in addition to containing a variant CD80 polypeptide, also contains at least one additional IgSF domain (e.g. a second IgSF domain) that is a vlgD that contains one or more amino acid modifications (e.g. substitution, deletion or mutation) compared to an IgSF domain in a wild-type or unmodified IgSF domain, such as an IgSF domain in an IgSF family member set forth in Table 2. In some 2023203586 08 Jun 2023 embodiments, the additional or second affinity-modified IgSF domain comprises at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to a wild-type or unmodified IgSF domain or a specific binding fragment thereof contained in the sequence of amino acids set forth in any of SEQ ID NOS: 1-27 and 348. In some embodiments, the wild-type or unmodified IgSF domain is an IgV domain or an IgC domain, such as an IgCl or IgC2 domain. In some embodiments, the additional or second IgSF domain is an affinity-modified IgV domain or IgC domain.

[0237] In some embodiments, the one or more additional IgSF domain (e.g. second IgSF) domain is an IgSF domain (e.g. IgV) of another IgSF family member that binds or recognizes a tumor antigen. In such embodiments, the IgSF family member serves as a tumor-localizing moiety, thereby bringing the vlgD of CD80 in close proximity to immune cells in the tumor microenvironment. In some embodiments, the additional IgSF domain (e.g. second IgSF) domain is an IgSF domain of NkP30, which binds or recognizes B7-H6 expressed on a tumor cell. In some embodiments, the at least one additional (e.g. second) IgSF domain, e.g. NkP30, is a vlgD that contains one or more amino acid modifications (e.g. substitutions, deletions or additions). In some embodiments, the one or more amino acid modifications increase binding affinity and / or selectivity to B7-H6 compared to unmodified IgSF domain, e.g. NkP30, such as by at least or at least about 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, 20-fold, 30-fold 40-fold or 50-fold. Among the exemplary polypeptides is an NKp30 variant that contains the mutations L30V / A60V / S64P / S86G with reference to positions in the NKp30 extracellular domain corresponding to positions set forth in SEQ ID NO:54.

[0238] Tables 3-5 provide exemplary polypeptides containing one or more affinity-modified IgSF domains that can be used in stack constructs provided herein. TABLE 3: Exemplary variant ICOSL polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO Wild-type 32 196 N52S 109 197 N52H 110 198 N52D 111 199 N52Y / N57Y / F138L / L203P 112 200 N52H / N57Y / Q100P 113 201 N52S / Y146C / Y152C 114 N52H / C198R 115 N52H / C140D / T225A 116 N52H / C198R / T225A 117 N52H / K92R 118 202 N52H / S99G 119 203 2023203586 08 Jun 2023 TABLE 3: Exemplary variant ICOSL polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO N52Y 120 204 N57Y 121 205 N57Y / Q100P 122 206 N52S / S130G / Y152C 123 N52S / Y152C 124 N52S / C198R 125 N52Y / N57Y / Y152C 126 N52Y / N57Y / H129P / C198R 127 N52H / L161P / C198R 128 N52S / T113E 129 S54A 130 207 N52D / S54P 131 208 N52K / L208P 132 209 N52S / Y152H 133 N52D / V151A 134 N52H / I143T 135 N52S / L80P 136 210 F120S / Y152H / N201S 137 N52S / R75Q / L203P 138 211 N52S / D158G 139 N52D / Q133H 140 N52S / N57Y / H94D / L96F / L98F / Q100R 141 212 N52S / N57 Y / H94D / L96F / L98F / Q100R / G103E / F120S 142 213 N52S / G103E 239 240 N52H / C140del / T225A 478 TABLE 4: Exemplary variant NKp30 polypeptides Mutation(s) ECD SEQ ID NO IgC-like domain SEQ ID NO Wild-type 54 214 L30V / A60V / S64P / S86G 143 215 L30V 144 216 A60V 145 217 S64P 146 218 S86G 147 219 TABLE 5: Exemplary variant CD86 polypeptides Mutation(s) ECD SEQ ID NO IgV SEQ ID NO Wild-type 29 220 Q35H / H90L / Q102H 148 221 Q35H 149 222 H90L 150 223 Q102H 151 224 2023203586 08 Jun 2023

[0239] In some embodiments, the two or more IgSF domain, including a vlgD of CD80 and one or more additional IgSF domain (e.g. second variant IgSF domain) from another IgSF family member, are covalently or non-covalently linked. A plurality of non-affinity modified and / or affinity modified IgSF domains in a stacked immunomodulatory protein polypeptide chain need not be covalently linked directly to one another. In some embodiments, the two or more IgSF domains are linked directly or indirectly, such as via a linker. In some embodiments, an intervening span of one or more amino acid residues indirectly covalently bonds IgSF domains to each other. The linkage can be via the N-terminal to C-terminal residues. In some embodiments, the linkage can be made via side chains of amino acid residues that are not located at the N-terminus or C-terminus of the IgSF domain(s). Thus, linkages can be made via terminal or internal amino acid residues or combinations thereof.

[0240] In some embodiments, one or more “peptide linkers” link the vlgD of CD80 and an additional IgSF domain (e.g. second variant IgSF domain). In some embodiments, a peptide linker can be a single amino acid residue or greater in length. In some embodiments, the peptide linker has at least one amino acid residue but is no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid residues in length. In some embodiments, the linker is (in one-letter amino acid code): GGGGS (“4GS”) or multimers of the 4GS linker, such as repeats of 2, 3, 4, or 5 4GS linkers. In some embodiments, the peptide linker is (GGGGSh or (GGGGS)3. In some embodiments, the linker also can include a series of alanine residues alone or in addition to another peptide linker (such as a 4GS linker or multimer thereof). In some embodiments, the number of alanine residues in each series is: 2, 3, 4, 5, or 6 alanines.

[0241] In some embodiments, the non-affinity modified and / or affinity modified IgSF domains are linked by “wild-type peptide linkers” inserted at the N-terminus and / or C-terminus of the first and / or second non-affinity modified and / or affinity modified IgSF domains. These linkers are also called leading sequences (N-terminal to non-affinity modified or affinity modified IgSF domain) or trailing sequences (C-terminal to non-affinity modified or affinity modified IgSF domain), and sequences that exist in the wild-type protein that span immediately outside the structural prediction of the Ig fold of the IgSF. In some embodiments, the “wild-type linker” is an amino acid sequence that exists after the signal sequence, but before in the IgSF domain, such as the defined IgV domain, in the amino acid sequence of the wild-type protein. In some embodiments, the “wild-type” linker is an amino acid sequence that exists immediately after the IgSF domain, such as immediately after the defined IgV domain but before the IgC 2023203586 08 Jun 2023 domain, in the amino acid sequence of the wild-type protein. These linker sequences can contribute to the proper folding and function of the neighboring IgSF domain(s). In some embodiments, there is present a leading peptide linker inserted at the N-terminus of the first IgSF domain and / or a trailing sequence inserted at the C-terminus of the first non-affinity modified and / or affinity modified IgSF domain. In some embodiments, there is present a second leading peptide linker inserted at the N-terminus of the second IgSF domain and / or a second trailing sequence inserted at the C-terminus of the second non-affinity modified and / or affinity modified IgSF domain. When the first and second non-affinity modified and / or affinity modified IgSF domains are derived from the same parental protein and are connected in the same orientation, wild-type peptide linkers between the first and second non-affinity modified and / or affinity modified IgSF domains are not duplicated. For example, when the first trailing wild-type peptide linker and the second leading wild-type peptide linker are the same, the Type II immunomodulatory protein does not comprise either the first trailing wild-type peptide linker or the second leading wild-type peptide linker.

[0242] In some embodiments, the Type II immunomodulatory protein comprises a first leading wild-type peptide linker inserted at the N-terminus of the first non-affinity modified and / or affinity modified IgSF domain, wherein the first leading wild-type peptide linker comprises at least 5 (such as at least about any of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more) consecutive amino acids from the intervening sequence in the wild-type protein from which the first non-affinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately preceding domain (such as a signal peptide or an IgSF domain). In some embodiments, the first leading wild-type peptide linker comprises the entire intervening sequence in the wild-type protein from which the first non-affinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately preceding domain (such as a signal peptide or an IgSF domain).

[0243] In some embodiments, the Type II immunomodulatory protein further comprises a first trailing wild-type peptide linker inserted at the C-terminus of the first non-affinity modified and / or affinity modified IgSF domain, wherein the first trailing wild-type peptide linker comprises at least 5 (such as at least about any of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more) consecutive amino acids from the intervening sequence in the wild-type protein from which the first non-affinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately following domain (such as an IgSF domain or a 2023203586 08 Jun 2023 transmembrane domain). In some embodiments, the first trailing wild-type peptide linker comprises the entire intervening sequence in the wild-type protein from which the first nonaffinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately following domain (such as an IgSF domain or a transmembrane domain).

[0244] In some embodiments, the Type II immunomodulatory protein further comprises a second leading wild-type peptide linker inserted at the N-terminus of the second non-affinity modified and / or affinity modified IgSF domain, wherein the second leading wild-type peptide linker comprises at least 5 (such as at least about any of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more) consecutive amino acids from the intervening sequence in the wild-type protein from which the second non-affinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately preceding domain (such as a signal peptide or an IgSF domain). In some embodiments, the second leading wild-type peptide linker comprises the entire intervening sequence in the wild-type protein from which the second non-affinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately preceding domain (such as a signal peptide or an IgSF domain).

[0245] In some embodiments, the Type II immunomodulatory protein further comprises a second trailing wild-type peptide linker inserted at the C-terminus of the second non-affinity modified and / or affinity modified IgSF domain, wherein the second trailing wild-type peptide linker comprises at least 5 (such as at least about any of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more) consecutive amino acids from the intervening sequence in the wild-type protein from which the second non-affinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately following domain (such as an IgSF domain or a transmembrane domain). In some embodiments, the second trailing wild-type peptide linker comprises the entire intervening sequence in the wild-type protein from which the second nonaffinity modified and / or affinity modified IgSF domain is derived between the parental IgSF domain and the immediately following domain (such as an IgSF domain or a transmembrane domain).

[0246] Exemplary trailing sequences for at Type II protein containing a CD80 IgSF domain, can contain the amino acid sequence set forth in SEQ ID NO: 232. Exemplary trailing sequences for a Type II protein containing a CD80 IgSF domain are set forth in SEQ ID NOS: 231, 232 and 371. Exemplary trailing sequences for a Type II protein containing an ICOSL IgSF domain are 2023203586 08 Jun 2023 set forth in SEQ ID NOS: 233 and 234. Exemplary leading and trailing sequences for a Type II protein containing a CD86 IgSF domain are set forth in SEQ ID NOS: 236-238. An exemplary trailing sequence for a Type II protein containing an NKp30 IgSF domain is set forth in SEQ ID NO:235.

[0247] In some embodiments, the two or more IgSF domain, including a vlgD of CD80 and one or more additional IgSF domain (e.g. second variant IgSF domain) from another IgSF family member, are linked or attached to an Fc to form a dimeric multi-domain stack immunomodulatory protein. In some embodiments, the variant CD80 polypeptide and second IgSF domain are independently linked, directly or indirectly, to the N- or C-terminus of an Fc subunit. In some embodiments, the variant CD80 polypeptide and second IgSF domain are linked, directly or indirectly, and one of the variant CD80 or second IgSF domain is also linked, directly or indirectly, to the N- or C-terminus of an Fc subunit. In some embodiments, linkage to the Fc is via a peptide linker, e.g. a peptide linker, such as described above. In some embodiments, linkage between the variant CD80 and second IgSF domain is via a peptide linker, e.g. a peptide linker, such as described above. In some embodiments, the vlgD of CD80, the one or more additional IgSF domains, and the Fc domain can be linked together in any of numerous configurations as depicted in FIG. 4. Exemplary configurations are described in the Examples.

[0248] In some embodiments, the stacked immunomodulatory protein is a dimer formed by two stacked immunomodulatory Fc fusion polypeptides. Also provided are nucleic acid molecules encoding any of the stacked immunomodulatory proteins. In some embodiments, the dimeric multi-domain stack immunomodulatory protein can be produced in cells by expression, or in some cases co-expression, of stack immunomodulatory Fc fusion polypeptides, such as described above in according with generating dimeric Fc fusion proteins.

[0249] In some embodiments, the dimeric multi-domain stack immunomodulatory protein is divalent for each Fc subunit, monovalent for each subunit, or divalent for one subunit and tetravalent for the other.

[0250] In some embodiments, the dimeric multi-domain stack immunomodulatory protein is a homodimeric multi-domain stack Fc protein. In some embodiments, the dimeric multi-domain stack immunomodulatory protein comprises a first stack immunomodulatory Fc fusion polypeptide and a second stack immunomodulatory Fc fusion polypeptide in which the first and second polypeptide are the same. In some embodiments, the Fc portion of the polypeptide can be any Fc as described above. 2023203586 08 Jun 2023

[0251] In some embodiments, the multi-domain stack molecule is heterodimeric, comprising two different Fc polypeptides wherein at least one is an Fc polypeptide containing at least one variant CD80 polypeptide and / or at least one second IgSF domain (e.g. second variant IgSF domain). In some embodiments, the multi-domain stack molecule contains a first Fc polypeptide containing a variant CD80 and a second IgSF domain and a second Fc polypeptide containing the variant CD80 and the second IgSF domain. In some embodiments, the multi-domain stack molecule contains a first Fc polypeptide containing a variant CD80 polypeptide and a second IgSF domain and a second Fc polypeptide that is not linked to either a variant CD80 polypeptide or second IgSF domain.

[0252] In some embodiments, the multi-domain stack molecule contains a first Fc polypeptides containing 1, 2, 3, 4 or more variant CD80 polypeptides and 1, 2, 3, 4 or more second IgSF domains, wherein the total number of IgSF domains in the first stack Fc polypeptide is greater than 2, 3, 4, 5, 6 or more. In one example of such an embodiment, the second stack Fc polypeptide contains 1, 2, 3, 4 or more variant CD80 polypeptides and 1, 2, 3, 4 or more second IgSF domains, wherein the total number of IgSF domains in the first stack Fc polypeptide is greater than 2, 3, 4, 5, 6 or more. In another example of such an embodiments, the second Fc polypeptide is not linked to either a variant CD80 polypeptide or second IgSF domain.

[0253] In some embodiments, the heterodimeric stack molecule contains a first stack immunomodulatory Fc fusion polypeptide and a second stack immunomodulatory Fc fusion polypeptide in which the first and second polypeptide are different. In some embodiments, a heterodimeric stack molecule contains a first Fc subunit containing a first variant CD80 polypeptide and / or second IgSF domain (e.g. second variant IgSF domain) and a second Fc subunit containing the other of the first variant CD80 polypeptide or the second IgSF domain. In some embodiments, the heterodimeric stack molecule contains a first stack immunomodulatory Fc fusion polypeptide and a second stack immunomodulatory Fc fusion polypeptide in which the first and second polypeptide are different. In some embodiments, a heterodimeric stack molecule contains a first Fc subunit containing a first variant CD80 polypeptide and / or second IgSF domain (e.g. second variant IgSF domain) and a second Fc subunit containing both the first variant CD80 polypeptide and second IgSF domain (e.g. second variant IgSF domain) but in a different orientation or configuration from the first Fc subunit. 2023203586 08 Jun 2023

[0254] In some embodiments, the Fc domain of one or both of the first and second stacked immunomodulatory Fc fusion polypeptide comprises a modification (e.g. substitution) such that the interface of the Fc molecule is modified to facilitate and / or promote heterodimerization. In some embodiments, modifications include introduction of a protuberance (knob) into a first Fc polypeptide and a cavity (hole) into a second Fc polypeptide such that the protuberance is positionable in the cavity to promote complexing of the first and second Fc-containing polypeptides. Amino acids targeted for replacement and / or modification to create protuberances or cavities in a polypeptide are typically interface amino acids that interact or contact with one or more amino acids in the interface of a second polypeptide.

[0255] In some embodiments, a first polypeptide that is modified to contain protuberance (hole) amino acids include replacement of a native or original amino acid with an amino acid that has at least one side chain which projects from the interface of the first polypeptide and is therefore positionable in a compensatory cavity (hole) in an adjacent interface of a second polypeptide. Most often, the replacement amino acid is one which has a larger side chain volume than the original amino acid residue. One of skill in the art knows how to determine and / or assess the properties of amino acid residues to identify those that are ideal replacement amino acids to create a protuberance. In some embodiments, the replacement residues for the formation of a protuberance are naturally occurring amino acid residues and include, for example, arginine (R), phenylalanine (F), tyrosine (Y), or tyrptophan (W). In some examples, the original residue identified for replacement is an amino acid residue that has a small side chain such as, for example, alanine, asparagines, aspartic acid, glycine, serine, threonine, or valine.

[0256] In some embodiments, a second polypeptide that is modified to contain a cavity (hole) is one that includes replacement of a native or original amino acid with an amino acid that has at least one side chain that is recessed from the interface of the second polypeptide and thus is able to accommodate a corresponding protuberance from the interface of a first polypeptide. Most often, the replacement amino acid is one which has a smaller side chain volume than the original amino acid residue. One of skill in the art knows how to determine and / or assess the properties of amino acid residues to identify those that are ideal replacement residues for the formation of a cavity. Generally, the replacement residues for the formation of a cavity are naturally occurring amino acids and include, for example, alanine (A), serine (S), threonine (T) and valine (V). In some examples, the original amino acid identified for replacement is an amino 2023203586 08 Jun 2023 acid that has a large side chain such as, for example, tyrosine, arginine, phenylalanine, or tryptophan.

[0257] The CH3 interface of human IgGl, for example, involves sixteen residues on each o domain located on four anti-parallel P-strands which buries 1090 A2 from each surface (see e.g., Deisenhofer et al. (1981) Biochemistry, 20:2361-2370; Miller et al., (1990) J Mol. Biol., 216, 965-973; Ridgway et al., (1996) Prot. Engin., 9: 617-621; U.S. Pat. No. 5,731,168). Modifications of a CH3 domain to create protuberances or cavities are described, for example, in U.S. Pat. No. 5,731,168; International Patent Applications WO98 / 50431 and WO 2005 / 063816; and Ridgway et al., (1996) Prot. Engin., 9: 617-621. In some examples, modifications of a CH3 domain to create protuberances or cavities are typically targeted to residues located on the two central anti-parallel P-strands. The aim is to minimize the risk that the protuberances which are created can be accommodated by protruding into the surrounding solvent rather than being accommodated by a compensatory cavity in the partner CH3 domain.

[0258] In some embodiments, the heterodimeric molecule contains a T366W mutation in the CH3 domain of the “knobs chain” and T366S, L368A, Y407V mutations in the CH3 domain of the “hole chain”. In some cases, an additional interchain disulfide bridge between the CH3 domains can also be used (Merchant, A. M., et al., Nature Biotech. 16 (1998) 677-681) e.g. by introducing a Y349C mutation into the CH3 domain of the “knobs” or “hole” chain and a E356C mutation or a S354C mutation into the CH3 domain of the other chain. In some embodiments, the heterodimeric molecule contains S354C, T366W mutations in one of the two CH3 domains and Y349C, T366S, L368A, Y407V mutations in the other of the two CH3 domains. In some embodiments, the heterodimeric molecule comprises E356C, T366W mutations in one of the two CH3 domains and Y349C, T366S, L368A, Y407V mutations in the other of the two CH3 domains. In some embodiments, the heterodimeric molecule comprises Y349C, T366W mutations in one of the two CH3 domains and E356C, T366S, L368A, Y407V mutations in the other of the two CH3 domains. In some embodiments, the heterodimeric molecule comprises Y349C, T366W mutations in one of the two CH3 domains and S354C, T366S, L368A, Y407V mutations in the other of the two CH3 domains. Examples of other knobs-in-holes technologies are known in the art, e.g. as described by EP 1 870 459 Al.

[0259] In some embodiments, the Fc subunits of the heterodimeric molecule additionally can contain one or more other Fc mutation, such as any described above. In some embodiments, the heterodimer molecule contains an Fc subunit with a mutation that reduces effector function. 2023203586 08 Jun 2023

[0260] In some embodiments, an Fc variant containing CH3 protuberance / cavity modifications can be joined to a stacked immunomodulatory polypeptide anywhere, but typically via its N- or C-terminus, to the N- or C-terminus of a first and / or second stacked immunomodulatory polypeptide, such as to form a fusion polypeptide. The linkage can be direct or indirect via a linker. Typically, a knob and hole molecule is generated by co-expression of a first stacked immunomodulatory polypeptide linked to an Fc variant containing CH3 protuberance modification(s) with a second stacked immunomodulatory polypeptide linked to an Fc variant containing CH3 cavity modification(s). C. Conjugates and Fusions of Variant Polypeptides and Immunomodulatory Proteins

[0261] In some embodiments, the variant polypeptides provided herein, which are immunomodulatory proteins comprising variants of an Ig domain of the IgSF family (vlgD), can be conjugated with or fused with a moiety, such as an effector moiety, such as another protein, directly or indirectly, to form a conjugate (“IgSF conjugate”). In some embodiments, the attachment can be covalent or non-covalent, e.g., via a biotin-streptavidin non-covalent interaction. In some embodiments of a CD80-Fc variant fusion, any one or combination of any two or more of the foregoing conjugates can be attached to the Fc or to the variant CD80 polypeptide or to both

[0262] In some embodiments, the moiety can be a targeting moiety, a small molecule drug (non-polypeptide drug of less than 500 daltons molar mass), a toxin, a cytostatic agent, a cytotoxic agent, an immunosuppressive agent, a radioactive agent suitable for diagnostic purposes, a radioactive metal ion for therapeutic purposes, a prodrug-activating enzyme, an agent that increases biological half-life, or a diagnostic or detectable agent.

[0263] In some embodiments the effector moiety is a therapeutic agent, such as a cancer therapeutic agent, which is either cytotoxic, cytostatic or otherwise provides some therapeutic benefit. In some embodiments, the effector moiety is a targeting moiety or agent, such as an agent that targets a cell surface antigen, e.g., an antigen on the surface of a tumor cell. In some embodiments, the effector moiety is a label, which can generate a detectable signal, either directly or indirectly. In some embodiments, the effector moiety is a toxin. In some embodiments, the effector moiety is a protein, peptide, nucleic acid, small molecule or nanoparticle. 2023203586 08 Jun 2023

[0264] In some embodiments, 1, 2, 3, 4, 5 or more effector moieties, which can be the same or different, are conjugated, linked or fused to the variant polypeptide or protein to form an IgSF conjugate. In some embodiments, such effector moieties can be attached to the variant polypeptide or immunomodulatory protein using various molecular biological or chemical conjugation and linkage methods known in the art and described below. In some embodiments, linkers such as peptide linkers, cleavable linkers, non-cleavable linkers or linkers that aid in the conjugation reaction, can be used to link or conjugate the effector moieties to the variant polypeptide or immunomodulatory protein.

[0265] In some embodiments, the IgSF conjugate comprises the following components: (protein or polypeptide), (L)q and (effector moiety)m, wherein the protein or polypeptide is any of the described variant polypeptides or immunomodulatory proteins capable of binding one or more cognate counter structure ligands as described; L is a linker for linking the protein or polypeptide to the moiety; m is at least 1; q is 0 or more; and the resulting IgSF conjugate binds to the one or more counter structure ligands. In particular embodiments, m is 1 to 4 and q is 0 to 8.

[0266] In some embodiments, there is provided an IgSF conjugate comprising a variant polypeptide or immunomodulatory protein provided herein conjugated with a targeting agent that binds to a cell surface molecule, for example, for targeted delivery of the variant polypeptide or immunomodulatory protein to a specific cell. In some embodiments, the targeting agent is a molecule(s) that has the ability to localize and bind to a molecule present on a normal cell / tissue and / or tumor cell / tumor in a subject. In other words, IgSF conjugates comprising a targeting agent can bind to a ligand (directly or indirectly), which is present on a cell, such as a tumor cell. The targeting agents of the invention contemplated for use include antibodies, polypeptides, peptides, aptamers, other ligands, or any combination thereof, that can bind a component of a target cell or molecule.

[0267] In some embodiments, the targeting agent binds a tumor cell(s) or can bind in the vicinity of a tumor cell(s) (e.g., tumor vasculature or tumor microenvironment) following administration to the subject. The targeting agent may bind to a receptor or ligand on the surface of the cancer cell. In another aspect of the invention, a targeting agent is selected which is specific for a noncancerous cells or tissue. For example, a targeting agent can be specific for a molecule present normally on a particular cell or tissue. Furthermore, in some embodiments, the same molecule can be present on normal and cancer cells. Various cellular components and 2023203586 08 Jun 2023 molecules are known. For example, if a targeting agent is specific for EGFR, the resulting IgSF conjugate can target cancer cells expressing EGFR as well as normal skin epidermal cells expressing EGFR. Therefore, in some embodiments, an IgSF conjugate of the invention can operate by two separate mechanisms (targeting cancer and non-cancer cells).

[0268] In various aspects of the invention disclosed herein an IgSF conjugate of the invention comprises a targeting agent which can bind / target a cellular component, such as a tumor antigen, a bacterial antigen, a viral antigen, a mycoplasm antigen, a fungal antigen, a prion antigen, an antigen from a parasite. In some aspects, a cellular component, antigen or molecule can each be used to mean, a desired target for a targeting agent. For example, in various embodiments, a targeting agent is specific for or binds to a component, which includes but is not limited to, epidermal growth factor receptor (EGFR, ErbB-1, HER1), ErbB-2 (HER2 / neu), ErbB-3 / HER3, ErbB-4 / HER4, EGFR ligand family; insulin-like growth factor receptor (IGFR) family, IGF-binding proteins (IGFBPs), IGFR ligand family; platelet derived growth factor receptor (PDGFR) family, PDGFR ligand family; fibroblast growth factor receptor (FGFR) family, FGFR ligand family, vascular endothelial growth factor receptor (VE...

Claims

1. A variant CD80 polypeptide, comprising an IgV domain and an IgC domain,wherein the variant CD80 polypeptide comprises amino acid substitutions withreference to an unmodified CD80 polypeptide;wherein the amino acid substitutions are selected from:E24G / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / H96R,R29D / Y31L / Q33H / K36G / M38I / T41A / M42T / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / L148S / N149S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / N149S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / N149S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / N144S / N149S, R29H / Y31H / T41G / Y87N / E88G / K89E / D90N / A91G / P109S,R29H / E52G / L70R / E88G / A91G / T130A, R29H / E52G / T120S / T130A,R29V / Y31F / K36G / M38L / M43Q / E81R / V83I / L85I / K89R / D90L / A91E / F92N / K93Q / R94G,R29V / M43Q / E81R / L85I / K89R / D90L / A91E / F92N / K93Q / R94G,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / M174T,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / H188D,H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / 2023203586   26 Jun 2026K93V / R94L / T120S / I127T / T130A / E143G / K169E / M174V / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / F108L / T120S / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T130A / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / K169E,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / C128Y / T130A / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94F / T130A / K169E,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T130A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93I / R94L / L97R / T130A / L148S,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / K169E,2502023203586   26 Jun 2026R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / I61N / E81V / L85R / K89N / A91T / F92P / K 93V / R94F / V104A / T120S / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / F92P / K93V / R94F / I 118V / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / T62S / E81V / L85R / K89N / A91T / F92P / K 93V / R94L / I118V / T120S / T130A / K169E / T175A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / F116S / T130A / H188D,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T120S / I127T / T130A / L142S / H188D,C16S / H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T110A / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / A91G / T120S / I127T / T130A / H188D, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / D76G / A91G / S103L / T120S / I127 T / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / S129L / H188D,H18L / R29D / Y31L / Q33H / K36G / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / H188D,S21P / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / N48I / V68A / E81V / L85R / K89N / A 91T / F92P / K93V / R94L / P109H / I126L / K169I,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91T / F92P / K93V / R94L / L97R,S21P / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / D90N / A91T / F92P / K93V / R94L / T130A / N149S / E162G,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / P74L / Y80N / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T130A / R190S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94F / E117V / I118T / N149S / S168G / H188Q,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / N64S / E81V / L85R / K89N / A91T / F92P / K93V / R94F / I118T / T130A / N149S / K169I,T28A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / V104L / T130A / N149S,2023203586   26 Jun 2026H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / L97R / N149S / H188Q,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / L97R / N149S,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T130A / N149S / T154I,A12G / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / V68A / E81V / L85R / K89N / A91T / F92P / K93V / R94L / L97R / T130A / L183H,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / T130A / S140T / N149S / K169S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / T130A / N149S / K169I / Q193L,V22A / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / T130A / N149S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / T130A / N149S,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118T / T130A / N149S / K169I,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94F / T130A / N149S / K169I, Q27R / R29C / M42T / S129P / E160G,R29H / E52G / D90N / I118V / T120S / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E / M174T,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / N48D / F59L / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / H188D,H18R / R29D / Y31L / Q33H / K36G / K37E / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E / H188D,2522023203586   26 Jun 2026R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / E143G / K169E / M174V / H188D,R29D / I30V / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K 93V / R94L / I118V / T120S / I127T / T130A / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L85R / K89N / A91T / F92P / K93V / R94L / I 118V / T120S / I127T / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / F108L / I118V / T120S / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / N149D / K169E / H188D,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / C128Y / T130A / H188D,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / E99D / T130A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / T130A / K169E,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / I61N / E81V / L85R / K89N / A91T / F92P / K 93V / R94F / V104A / I118V / T120S / I126V / T130A,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94F / I118V / T120S / T130A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / L142S / H188D,C16S / H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T110A / I118V / H188D,R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / A91G / I118V / T120S / I127T / T130A / H182532023203586   26 Jun 20268D, R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / L70Q / D76G / A91G / S103L / I118V / T120 S / I127T / T130A,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / I118V / T120S / I127T / T130A / H188D,H18L / R29D / Y31L / Q33H / K36G / M38I / T41A / M43R / M47T / E81V / L85R / K89N / A91T / F92P / K93V / R94L / T130A / N149S,, corresponding to numbering of positions set forth in SEQ ID NO:28;wherein the unmodified CD80 polypeptide comprises (i) the sequence of amino acids set forth in SEQ ID NO:28, or (ii) a portion of the sequence of amino acids set forth in SEQ ID NO:28 comprising a sequence of amino acids of an IgV domain and an IgC domain of a CD80 polypeptide; andwherein the variant CD80 polypeptide exhibits decreased affinity to the ectodomain of CTLA-4 compared to the unmodified CD80 polypeptide.

2. The variant CD80 polypeptide of claim 1, wherein the sequence of aminoacids of the IgV domain of the unmodified CD80 polypeptide comprises amino acid residues 35-135, corresponding to the numbering of SEQ ID NO: 1.

3. The variant CD80 polypeptide of claim 1 or 2, wherein the sequence of aminoacids of the IgC domain of the unmodified CD80 polypeptide comprises amino acid residues 145-230, corresponding to the numbering of SEQ ID NO:1.

4. The variant CD80 polypeptide of any one of claims 1-3, comprising thesequence of amino acids set forth in any one of SEQ ID NOS: 78, 82, 92-97, 105, 107, 280310, 313, 315, 317-342, 344, 434, 446 or 475 or a specific binding fragment thereof, or asequence of amino acids that exhibits at least 95% sequence identity to any one of SEQ ID NOS: 78, 82, 92-97, 105, 107, 280-310, 313, 315, 317-342, 344, 434, 446 or 475 or a specific binding fragment thereof and that contains the amino acid substitutions.

5. The variant CD80 polypeptide of any one of claims 1-4, wherein the affinityfor the ectodomain of CTLA-4 is decreased more than 1.2-fold, 1.5-fold, 2-fold, 3-fold, 4-2023203586   26 Jun 2026fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, 20-fold, 30-fold 40-fold or 50-fold compared to the unmodified CD80 polypeptide.

6. The variant CD80 polypeptide of any one of claims 1-5, wherein:(a) the variant CD80 polypeptide is linked to a multimerization domain;(b) the variant CD80 polypeptide is a multimeric polypeptide, optionally a dimeric polypeptide, comprising a first variant CD80 polypeptide linked to a multimerization domain and a second variant CD80 polypeptide linked to a multimerization domain; and / or(c) the multimerization domain is an Fc domain or a variant thereof with reduced effector function.

7. The variant CD80 polypeptide of claim 6, wherein the multimerization domainis a mammalian, optionally human Fc domain or a variant IgG1 Fc domain with reduced effector function, wherein the variant IgG1 Fc domain comprises one or more amino acid modifications compared to an unmodified Fc domain that is mammalian, optionally human.

8. The variant CD80 polypeptide of claim 7, wherein the Fc domain or variantIgG1 Fc domain comprises the sequence of amino acids set forth in SEQ ID NO:226 or SEQ ID NO:227 or a sequence of amino acids that exhibits at least 85% sequence identity to SEQ ID NO:226 or SEQ ID NO:227.

9. The variant CD80 polypeptide of claim 7 or 8, wherein the variant CD80polypeptide is linked to the Fc domain indirectly via a linker.

10. An immunomodulatory polypeptide, comprising the variant CD80 of any one of claims 1-9 linked to a second polypeptide comprising an immunoglobulin superfamily (IgSF) domain.

11. A conjugate, comprising the variant CD80 of any one of claims 1-9 or the immunomodulatory polypeptide of claim 10 linked to a moiety.

12. A nucleic acid molecule(s) encoding the variant CD80 polypeptide of any one of claims 1-9 or the immunomodulatory polypeptide of claim 10.2552023203586   26 Jun 202613.    A vector, comprising the nucleic acid molecule of claim 12.

14. A cell comprising the vector of claim 13.

15. A method of producing a variant CD80 polypeptide or an immunomodulatory protein, comprising introducing a nucleic acid or nucleic acid molecule(s) encoding the variant CD80 polypeptide of any one of claims 1-9 or the immunomodulatory protein of claim 10 into a host cell under conditions to express the variant CD80 polypeptide or the immunomodulatory protein in the cell, and isolating or purifying the variant CD80 polypeptide or the immunomodulatory protein from the cell.

16. A pharmaceutical composition, comprising the variant CD80 polypeptide of any one of claims 1-9, the immunomodulatory protein of claim 10, or the conjugate of claim 11.

17. A method of modulating an immune response in a subject, comprising administering the pharmaceutical composition of claim 16 to the subject, wherein modulating the immune response treats a disease or condition in the subject.

18. Use of the pharmaceutical composition of claim 16 in the manufacture of a medicament for modulating an immune response in a subject, wherein modulating the immune response treats a disease or condition in the subject.

19. The method of claim 17 or the use of claim 18, wherein the disease or condition is an inflammatory or autoimmune disease or condition.

20. The method of claim 17 or 19 or the use of claim 18 or 19, wherein the disease or condition is a Type 1 diabetes, an Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, a vasculitis, an autoimmune skin disease, transplantation, a Rheumatic disease, an inflammatory gastrointestinal disease, an inflammatory eye disease, an inflammatory neurological disease, an inflammatory pulmonary disease, an inflammatory endocrine disease, or an autoimmune hematological disease.2562023203586   26 Jun 202621. The method or use of claim 19, or claim 20, wherein the disease or condition is selected from inflammatory bowel disease, transplant, Crohn's disease, ulcerative colitis, multiple sclerosis, asthma, rheumatoid arthritis, or psoriasis.