Use of an immunoconjugate that binds to the cd123 antigen

Description

"USE OF AN IMMUNOCONJUGATE THAT BINDS TO THE CD123 ANTIGEN" Separated from BR112017027254-7, filed on 06 / 28 / 2016. Related to orders.

[001] This application claims the benefit of the filing date pursuant to 35 U.S.C. §119(e) of U.S. Provisional Application No. 62 / 186,161, filed June 29, 2015, U.S. Provisional Application No. 62 / 338,203, filed May 18, 2016, and U.S. Provisional Application No. 62 / 346,730, filed June 7, 2016. The entire content of each of the aforementioned applications is incorporated herein by reference. FIELD OF INVENTION

[002] The present invention relates generally to antibodies, antigen-binding fragments thereof, polypeptides and immunoconjugates that bind to the CD123 antigen (the α chain of the interleukin-3 receptor, or IL-3Ra). The present invention also relates to methods of using these CD123-binding molecules for the diagnosis and treatment of diseases, such as B-cell malignancies. BACKGROUND OF THE INVENTION

[003] CD123 (interleukin-3 receptor alpha, IL-3Rα) is a 40 kDa molecule that is part of the interleukin-3 receptor (IL-3R) complex. The cytokine interleukin-3 (IL-3) triggers the early differentiation of multipotent stem cells into erythroid, myeloid, and lymphoid progenitor cells. CD123 is expressed on committed CD34+ progenitors, but not by normal CD34+ / CD38- hematopoietic stem cells (HSCs). CD123 is expressed by basophils, mast cells, plasmacytoid dendritic cells, some expression by monocytes, macrophages, and eosinophils, and low or no expression by neutrophils and megakaryocytes. Some tissues Petition 870260060475, dated 06 / 19 / 2026, page 7 / 752 2 / 355 non-hematopoietic stem cells, such as placenta, Leydig cells of the testis, certain elements of brain cells, and some endothelial cells, also express CD123. However, the expression is primarily cytoplasmic.

[004] CD123 is reported to be expressed by leukemic blast cells (leukemia blasts) and leukemic stem cells (LSCs) (Jordan et al., Leukemia 14:1777-1784, 2000; Jin et al., Blood 113:6603-6610, 2009). In normal human precursor populations, CD123 is expressed by a subset of hematopoietic progenitor cells (HPCs), but not by normal HSCs. CD123 is also reported to be expressed by plasmacytoid dendritic cells (pDCs) and basophils and, to a lesser extent, monocytes and eosinophils.

[005] CD123 has been reported to be overexpressed in malignant cells in a wide variety of hematological malignancies including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) (Munoz et al., Haematologica 86(12):1261-1269, 2001). CD123 overexpression is associated with a poorer prognosis in AML (Tettamanti et al., Br. J. Haematol. 161: 389-401, 2013). AML and MDS are thought to arise from and be perpetuated by a small population of leukemic stem cells (LSCs), which are generally dormant (i.e., not rapidly dividing cells) and therefore resistant to cell death (apoptosis) and conventional chemotherapeutic agents. LSCs are characterized by the overexpression of CD123, whereas CD123 is not present in the corresponding normal population of hematopoietic stem cells in normal human bone marrow (Jin et al., Blood 113:6603-6610, 2009; Jordan et al., Leukemia 14:1777-1784, 2000).CD123 expression is also associated with several other malignancies / pre-malignacies: chronic myeloid leukemia (CML) progenitor cells (including blast crisis CML); cells of... Petition 870260060475, dated 06 / 19 / 2026, page 8 / 752 3 / 355 Reed-Sternberg Hodgkin's lymphoma (RS); transformed non-Hodgkin lymphoma (NHL); some chronic lymphocytic leukemia (CLL) (CD11c+); a subset of acute T-lymphoblastic leukemia (T-ALL) (16%, mostly immature, primarily adult), plasmacytoid dendritic cell (pDC) malignancies (DC2) and CD34+ / CD38- myelodysplastic syndrome (MDS) bone marrow malignancies.

[006] AML is a clonal disease characterized by the proliferation and accumulation of transformed myeloid progenitor cells in the bone marrow, which ultimately leads to hematopoietic failure. The incidence of AML increases with age, and older patients generally have worse treatment outcomes than younger patients (Robak et al., Clin. Ther. 2:2349-2370, 2009). Unfortunately, currently, most adults with AML die from the disease.

[007] Treatment for AML initially focuses on inducing remission (induction therapy). Once remission is achieved, treatment shifts to focus on securing that remission (post-remission or consolidation therapy) and, in some cases, maintenance therapy. The standard remission induction paradigm for AML is chemotherapy with an anthracycline / cytarabine combination, followed by consolidation chemotherapy, usually with higher doses of the same drugs used during the induction period or human stem cell transplantation, depending on the patient's ability to tolerate intensive treatment and the likelihood of cure with chemotherapy alone (see Roboz, Curr. Opin. Oncol. 24:711-719, 2012).

[008] Agents frequently used in induction therapy include cytarabine and anthracyclines. Cytarabine, also known as AraC, kills cancer cells and other normal cells that become cancerous. Petition 870260060475, dated 06 / 19 / 2026, page 9 / 752 4 / 355 divide rapidly, interfering with DNA synthesis. Side effects associated with AraC treatment include decreased resistance to infection, resulting from decreased white blood cell production; hemorrhage, as a result of decreased platelet production; and anemia, due to a potential reduction in red blood cells. Other side effects include nausea and vomiting. Anthracyclines (e.g., daunorubicin, doxorubicin, and idarubicin) exhibit various modes of action, including inhibition of DNA and RNA synthesis, disruption of higher-order DNA structures, and production of cell-damaging free oxygen radicals. The most consequential adverse effect of anthracyclines is cardiotoxicity, which considerably limits the administered dose lifetime and, to some extent, their usefulness.

[009] Thus, unfortunately, despite substantial progress in the treatment of newly diagnosed AML, 20% to 40% of patients do not achieve remission with standard induction chemotherapy and 50% to 70% of patients who enter a first complete remission are likely to relapse within 3 years. The ideal strategy at the time of relapse, or for patients with resistant disease, remains uncertain. Stem cell transplantation has been established as the most effective form of antileukemic therapy in AML patients in first or subsequent remission (Roboz, 2012).

[0010] Antibody-drug conjugates (ADCs) and other cell-binding agent-drug conjugates are emerging as a powerful class of antitumor agents with efficacy in a variety of cancers. Cell-binding agent-drug conjugates (such as ADCs) are generally composed of three distinct elements: a cell-binding agent (e.g., an antibody); a ligand; and a cytotoxic moiety. Conventionally, the cytotoxic drug moiety is covalently linked to residues of Petition 870260060475, dated 06 / 19 / 2026, page 10 / 752 5 / 355 lysine in the antibody, or cysteine ​​residues, obtained through the reduction of disulfide bonds between chains, resulting in ADCs that are heterogeneous mixtures containing varying numbers of drugs bound at different positions in the antibody molecule. SUMMARY OF THE INVENTION

[0011] The present invention is based on the surprising findings that the conjugates of the present invention are highly potent against various cancer cells expressing CD123, particularly leukemia with at least one negative prognostic factor.

[0012] One aspect of the invention provides an antibody or its antigen-binding fragment that: (a) binds to an epitope in amino acids 101 to 346 of the human CD123 / IL3-Ra antigen and (b) inhibits IL3-dependent proliferation in antigen-positive TF-1 cells.

[0013] In certain embodiments, the antibody or its antigen-binding fragment binds to an epitope within amino acids 101 to 204 of the human CD123 antigen. In another embodiment, the antibody or its antigen-binding fragment binds to an epitope in amino acids 205 to 346 of the human CD123 antigen.

[0014] A related aspect of the invention provides an antibody or antigen-binding fragment thereof that: (a) binds an epitope within amino acids 1 to 100 of human CD123 antigen and (b) inhibits IL3-dependent proliferation in antigen-positive TF-1 cells, with an IC50 value of 0.1 nM or less (e.g., 0.08 nM, 0.05 nM, 0.03 nM).

[0015] In certain embodiments, the antibody or its antigen-binding fragment inhibits the proliferation of leukemic stem cells or leukemic blast cells, but not hematopoietic stem cells.

[0016] In certain embodiments, the antibody or its fragment of Petition 870260060475, dated 06 / 19 / 2026, page 11 / 752 6 / 355 antigen binding binds to cells positive for human CD123 antigen with a dissociation constant (Kd) of 0.3 nM or lower, such as between 0.01 nM and 0.3 nM, between 0.01 nM and 0.2 nM, between 0.01 nM and 0.19 nM, between 0.01 nM and 0.18 nM, between 0.01 nM and 0.15 nM, or between 0.01 nM and 0.1 nM.

[0017] In certain embodiments, the antibody or its antigen-binding fragment binds to cynomolgus monkey CD123. For example, the antibody or its antigen-binding fragment may bind to cynomolgus monkey CD123 with a Kd between 0.05 and 0.3 nM, between 0.05 and 0.2 nM, between 0.05 nM and 0.19 nM, between 0.05 nM and 0.18 nM, between 0.05 nM and 0.15 nM, or between 0.05 and 0.1 nM. In certain embodiments, the antibody or its antigen-binding fragment binds human and cynomolgus monkey CD123 with substantially similar binding affinity. For example, the antibody or its antigen-binding fragment can bind to human and cynomolgus monkey CD123 with a Kd between 0.05 and 0.3 nM, between 0.05 and 0.2 nM, or between 0.05 and 0.1 nM. Kd can be measured by flow cytometry, surface plasma resonance, or radioimmunoassay.

[0018] In certain embodiments, the antibody or its antigen-binding fragment inhibits at least 50% of IL3-dependent proliferation in antigen-positive TF-1 cells at a concentration of 0.5 nM or lower.

[0019] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) at least one variable heavy chain region or a fragment thereof comprising three sequence complementarity-determining regions (CDRs) CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 1, 5 and 12, CDR2 is selected from the group consisting of SEQ ID NOs: 2, 3, 6-10, 13 and 14, and, Petition 870260060475, dated 06 / 19 / 2026, p. 12 / 752 7 / 355 optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 4, 11, 15 and 70; and b) at least one variable light chain region or a fragment thereof comprising three sequence complementarity-determining (CDR) regions CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 16, 19, 20, 23 and 72, CDR2 is selected from the group consisting of SEQ ID NOs: 17, 21, 24 and 71 and, optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 18, 22 and 25.

[0020] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) at least one variable heavy chain region or its fragment comprising three sequence complementarity-determining regions (CDRs) CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 1, 5 and 12, CDR2 is selected from the group consisting of SEQ ID NOs: 2, 3, 6-10, 13 and 14 and, optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 4, 11 and 15;(b) at least one variable light chain region or fragment thereof comprising three sequence complementarity-determining (CDR) regions CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 16, 19, 20 and 23, CDR2 is selected from the group consisting of SEQ ID NOs: 17, 21 and 24 and, optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 18, 22 and 25.

[0021] In certain embodiments, conservative amino acid substitutions comprise a substitution of at least one Lys Petition 870260060475, dated 06 / 19 / 2026, p. 13 / 752 8 / 355 in a CDR by an Arg.

[0022] In certain embodiments, the antibody is a humanized antibody grafted with CDR comprising mouse CDR regions, wherein one or more (e.g., 1, 2, 3, 4, 5, 6, 7 or 8) of the heavy chain region and / or the light chain region, vernier zone residues of said antibody are of mouse origin.

[0023] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 39 or 40; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41.

[0024] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 34; and b) a variable immunoglobulin light chain region with the amino acid sequence as set out in SEQ ID NO: 35. In certain embodiments, Xaa, the second N-terminus residue of SEQ ID NO: 34, is Phe. In other embodiments, Xaa is Val.

[0025] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable region of immunoglobulin heavy chain having the amino acid sequence shown in SEQ ID NO: 39 or 40; except that in which the N-terminal residue is Ser; and b) a variable region of immunoglobulin light chain having the amino acid sequence shown in SEQ ID NO: 41.

[0026] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable region of immunoglobulin heavy chain having the sequence of Petition 870260060475, dated 06 / 19 / 2026, page 14 / 752 9 / 355 amino acids presented in SEQ ID NO: 39 or 40; and b) a variable region of immunoglobulin light chain having the amino acid sequence presented in SEQ ID NO: 41, except for the one in which the N-terminal residue is Ser.

[0027] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 59 or 60, except that in which the N-terminal residue is Ser and except that in which the residue corresponding to the 5th to last residue of SEQ ID NO: 54 is Cys (i.e., Cys at EU / OU numbering position 442); and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41.

[0028] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 59 or 60, except that in which the residue corresponding to the 5th to last residue of SEQ ID NO: 54 is Cys; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41, except that in which the N-terminal residue is Ser.

[0029] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 38; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 35.

[0030] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable region of immunoglobulin heavy chain having the sequence of Petition 870260060475, dated 06 / 19 / 2026, page 15 / 752 10 / 355 amino acids presented in SEQ ID NO: 34; and b) a variable region of immunoglobulin light chain possessing the amino acid sequence presented in SEQ ID NO: 37.

[0031] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 56; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 35.

[0032] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 54; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 37.

[0033] In certain embodiments, Xaa, the second residue of the terminal N of the SEQ ID NOS: 38, 34, 56 and 54 is Phe. In other modes, Xaa is Val.

[0034] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 59 or 60, except that in which the residue corresponding to the 5th to last residue of SEQ ID NO: 54 is Cys; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41.

[0035] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 54; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in Petition 870260060475, dated 06 / 19 / 2026, page 16 / 752 11 / 355 SEQ ID NO: 35.

[0036] In certain embodiments, Xaa, the second residue of the terminal N of SEQ ID NO: 54 or 56, is Phe. In other embodiments, Xaa is Val.

[0037] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable immunoglobulin heavy chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 1, a CDR2 having an amino acid sequence presented in SEQ ID NO: 2 or 3, and a CDR3 having an amino acid sequence presented in SEQ ID NO: 4; and b) a variable immunoglobulin light chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 16, a CDR2 having an amino acid sequence presented in SEQ ID NO: 17, and a CDR3 having an amino acid sequence presented in SEQ ID NO: 18.

[0038] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable immunoglobulin heavy chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 5, a CDR2 having an amino acid sequence presented in SEQ ID NO: 6, 7, 8, 9 or 10, and a CDR3 having an amino acid sequence presented in SEQ ID NO: 11; and, b) a variable immunoglobulin light chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 19 or 20, a CDR2 having an amino acid sequence presented in SEQ ID NO: 21 and a CDR3 having an amino acid sequence presented in SEQ ID NO: 22.

[0039] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a variable immunoglobulin heavy chain region comprising a CDR1 Petition 870260060475, dated 06 / 19 / 2026, page 17 / 752 12 / 355 having an amino acid sequence presented in SEQ ID NO: 12, a CDR2 having an amino acid sequence presented in SEQ ID NO: 13 or 14, and a CDR3 having an amino acid sequence presented in SEQ ID NO: 15; and b) a variable immunoglobulin light chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 23, a CDR2 having an amino acid sequence presented in SEQ ID NO: 24, and a CDR3 having an amino acid sequence presented in SEQ ID NO: 25.

[0040] In certain embodiments, the antibody or its antigen-binding fragment may comprise: a) a Vh sequence at least 95% identical to a Vh reference sequence selected from the group consisting of SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (preferably 26, 28, 30, 32, 34 and 38); and / or, b) a Vl sequence at least 95% identical to a Vl reference sequence selected from the group consisting of SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (preferably 27, 29, 31, 35 and 37). In certain modes, the Vh sequence is at least 99% identical to one of the following SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (preferably 26, 28, 30, 32, 34 and 38) and / or where the Vl sequence is at least 99% identical to one of the following SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (preferably 27, 29, 31, 35 and 37).In embodiments, the antibody or its antigen-binding fragment may comprise: a) a Vh sequence selected from the group consisting of SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (preferably 26, 28, 30, 32, 34 and 38); and / or, b) a Vl sequence selected from the group consisting of SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (preferably 27, 29, 31, 35 and 37). In certain embodiments, the antibody or its antigen-binding fragment may comprise a Vh sequence of SEQ ID NO: 26 and a Vl sequence of SEQ ID NO: 27, or a Vh sequence of SEQ ID NO: 28 and a Vl sequence. Petition 870260060475, dated 06 / 19 / 2026, p. 18 / 752 13 / 355 of SEQ ID NO: 29 or a Vh sequence of SEQ ID NO: 30 and a Vh sequence of SEQ ID NO: 31 or a Vh sequence of SEQ ID NO: 34 and a Vl sequence of SEQ ID NO: 35.

[0041] In certain embodiments, the antibody is a murine, non-human mammalian, chimeric, humanized, or human antibody. For example, the humanized antibody may be a CDR-grafted antibody or a coated antibody. In certain embodiments, the antibody is a full-length antibody. In certain embodiments, its antigen-binding fragment is a Fab, Fab', F(ab')2, Fd, single-chain Fv or scFv, disulfide-linked Fv, V-NAR domain, IgNar, intrabody, IgGΔCH2, minibody, F(ab')3, tetrabody, triacorb, dibody, single-domain antibody, DVD-Ig, Fcab, mAb2, (scFv)2, or scFv-Fc.

[0042] Another aspect of the invention provides a polypeptide comprising the Vh and Vl sequences of either of the subject's antibodies or their antigen-binding fragment. The polypeptide may be a fusion with a protein that is not a Pseudomonas toxin.

[0043] Another aspect of the invention provides a cell that produces the antibody or its antigen-binding fragment of the invention, or the polypeptide of the invention.

[0044] Another aspect of the invention provides a method for producing the antibody or its antigen-binding fragment of the invention, or the polypeptide of the invention, comprising: (a) culturing the cell of the invention; and, (b) isolating the antibody, its antigen-binding fragment or the polypeptide from the cultured cell. In certain embodiments, the cell is a eukaryotic cell.

[0045] Another aspect of the invention provides an immunoconjugate with the following formula: CBA—(^CyL1' ' wL, where: Petition 870260060475, dated 06 / 19 / 2026, page 19 / 752 14 / 355 CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, which is covalently linked through a lysine residue to CyL1; Wl is an integer from 1 to 20; and CyL1 is represented by the following formula: or a pharmaceutically acceptable salt thereof, where: The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M; W' is -NRe', Re' is -(CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Petition 870260060475, dated 06 / 19 / 2026, p. 20 / 752 15 / 355 Rké -H ou -Me; Rx3 is a (C1-C6)alkyl group; L' is represented by the following formula: -NR5-PC(=O)-(CRaRb)mC(=O)- (B1'); or -NR5-PC(=O)-(CRaRb)mS-Zs1- (B3'); R5 is -H or a (C1-C3)alkyl group; P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; Ra and Rb, for each occurrence, are each independently -H, (C1-C3)alkyl, or a charged substituent or an ionizable group Q; m is an integer from 1 to 6; and Zs1 is selected from any of the following formulas: (b3); (b1); (b2); (b9); and in which: q is an integer from 1 to 5; and M is H+ or a cation.

[0046] In certain modalities, Ra and Rb are both H; and R5 is H or Petition 870260060475, dated 06 / 19 / 2026, p. 21 / 752 16 / 355 Me.

[0047] In some embodiments, P is a peptide containing 2 to 5 amino acid residues. For example, P can be selected among Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, AlaLys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N9-to-trosil-Arg, Phe-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), Gly-Leu (SEQ ID NO: 57), Leu-Ala-Leu (SEQ ID NO: 57). 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-A, Alag-A, Alag D-No-No, D-No-D-No, No-Meth and Met-No. In some modalities, P is Gly-Gly-Gly, Wing-Val, Wing-Wing, Wing-D-Wing, D-Wing-Wing or D-Wing-D-Wing.

[0048] In some embodiments, Q is -SO3M.

[0049] In some embodiments, the immunoconjugate is represented by the following formula: Petition 870260060475, de 19 / 06 / 2026, pág. 22 / 752 17 / 355 C? H? H X. 0 H X 0 xA^XCh ΪΝ'OMe MeO^^XN JU 0 ° υ Γ « > A Α ​​A „fx / \ , HN γ N Π χ X. 0 H χ 0 ' ιΑ y y- .U McO^ U ° ° υ hU! jy^^ γ * Xy ° * h ΡγνΆΑνΑ gí^°z Ay u H f Λ ΐ Ξ 0 H J Η Α ί / NU'X'Me MeOZUU.. U 0 0 ϊ ! Λ ην-Χ<ν~7| / ^ν ϊ = ο H χ χ J γ, γ |1 1 N—,h U MeoX^h^-N Ο 0 0 \ / θ ' X υ. XS N—CBA H so3m > JwL . J / ο A Αν / \ AS N--CBA H so3m >- J WL . J γ > ç .. . J N' C Β A ,Υ > h .. J H CBA 0 γ > wL J H —CBA Ο γ > Ò A wL Petition 870260060475, de 19 / 06 / 2026, pág. 23 / 752 18 / 355 Petition 870260060475, de 19 / 06 / 2026, pág. 24 / 752 19 / 355 Petition 870260060475, de 19 / 06 / 2026, pág. 25 / 752 20 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 26 / 752 21 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 27 / 752 22 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 28 / 752 23 / 355 or a pharmaceutically acceptable salt thereof, where Wl is an integer from 1 to 10; the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H; and when it is a connection Petition 870260060475, dated 06 / 19 / 2026, p. 29 / 752 24 / 355 simple, X will be -H, and Y will be -OH or -SO3M.

[0050] A related aspect provides an immunoconjugate with the formula: CBa4—CyL2' ' wLem que: CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, which is covalently linked to CyL2 through a lysine residue; Wl is an integer from 1 to 20; and CyL2 is represented by the following formula: Rx1 THE R® 2 N ; or or a pharmaceutically acceptable salt thereof, where: Petition 870260060475, dated 06 / 19 / 2026, p. 30 / 752 25 / 355 The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or a protecting amine portion, and Y will be -OH or -SO3M; Rx1 and Rx2 are independently (C1-C6) alkyl; Reé -H or a (C1-C6)alkyl; W' is -NRe', Re' is -(CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Zs1 is selected from any of the following formulas: the N O / (CH2)q9 N0(b3); (b1); O H V H ” H (b4); the (b2); SO3M 0(b5), o N (b6), (b7); the (b8); the (b9); and so3M s o (b10), where: q is an integer from 1 to 5; and M is -H+ or a cation.

[0051] In certain embodiments, Re is H or Me; Rx1 and Rx2 are independently - (CH2)p- (CRfRg) -, where Rf and Rg are each independently -H or (C1-C4)alkyl; ep is 0, 1, 2 or 3. Petition 870260060475, dated 06 / 19 / 2026, p. 31 / 752 26 / 355

[0052] In certain modalities, Rfe Rgsão igual ou diferentes, e são escolhidos de -H e -Me.

[0053] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 32 / 752 27 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 33 / 752 28 / 355 or a pharmaceutically acceptable salt thereof, where Wl is an integer from 1 to 10; the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H; and when it is a single bond, X will be -H, and Y will be -OH or -SO3M.

[0054] In certain embodiments, the double line — between N and C represents a double bond, X is absent and Y is -H. In certain embodiments, the double line — between N and C represents a single bond, X is -H and Y is -SO3M. In certain embodiments, M is H+, Na+ or K+.

[0055] Another related aspect of the invention provides an immunoconjugate with the following formula: CBA 4—CyL3) ' ' wL, where: CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, which is covalently linked to CyL3 through a Lys residue; Wl is an integer from 1 to 20; CyL3 is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 34 / 752 29 / 355 m' is 1 or 2; Ri and R2 are each independently H or a (C1-C3) alkyl group; and Zs1 is selected from any of the following formulas: (b3); (bi); (b2); (b5),0(b4); (b7); (b8); and (b6), (b9), where: q is an integer from 1 to 5; and M is H+ or a cation.

[0056] In certain modalities, m' is 1 and Ri and R2 are both H. In certain other modalities, m' is 2 and Ri and R2 are both Me.

[0057] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 35 / 752 30 / 355 CBA MeO or CBA MeO HO H, ou wL MeO HO H CBA or a pharmaceutically acceptable salt thereof, where Wl is an integer from 1 to 10.

[0058] In certain forms, M is H+, Na+ or K+.

[0059] Another aspect of the invention provides an immunoconjugate with the following formula: in which: CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to the Jcb' group; Ws is 1, 2, 3, or 4; Jcb' is a moiety formed by the reaction of an aldehyde group derived from the oxidation of a 2-hydroxyethylamine moiety (where the moiety of Petition 870260060475, dated 06 / 19 / 2026, p. 36 / 752 31 / 355 2-hydroxyethylamine may be part of a serine, threonine, hydroxylysine, 4-hydroxyornithine or valeric acid (2,4-diamino-5-hydroxy) residue at an N-terminus of said antibody or antigen-binding fragment thereof, or its polypeptide of the invention, and a reactive aldehyde group at Cys1, and is represented by the following formula: . n2h s1|—C -N. s2 ; j J ; where s1 is the site covalently linked to CBA; and s2 is the site covalently linked to Cys1; Cys1 is represented by the following formula: or or a pharmaceutically acceptable salt thereof, where: Petition 870260060475, dated 06 / 19 / 2026, p. 37 / 752 32 / 355 The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M, and M will be H+ or a cation; R5 is -H or a (C1-C3)alkyl group; P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; Zd1 is missing, -C(=O)-NR9-, or -NR9-C(=O)-; R9 is -H or a (C1-C3)alkyl group; Ra and Rb, for each occurrence, are independently -H, (C1C3)alkyl, or a charged substituent or an ionizable group Q; re r' are independently integers from 1 to 6; W' is -NRe', Re' is -(CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx3 is a (C1-C6)alkyl group; L is -NR9-(CRaRb)r or absent; er is an integer from 0 to 6.

[0060] For simplicity, in each instance below reciting Ser as the N-terminal residue, it should be understood that another portion of 2-hydroxyethylamine, as part of a serine, threonine, hydroxylysine, 4-hydroxyornithine, or 2,4-diamino-5-hydroxy valeric acid residue, is contemplated when applicable, especially in relation to Thr.

[0061] In certain modalities, Ra and Rb are H and R5 and R9 are both H or Me.

[0062] In some embodiments, P is a peptide containing 2 to 5 amino acid residues. For example, P can be selected from the group consisting of: Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Petition 870260060475, of 19 / 06 / 2026, p. 38 / 752 33 / 355 Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N9-tosyl-Arg, Phe-N9-nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, GlyPhe-Lys, Leu-Ala, Leu Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), Gly-Phe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, Arg-D-Arg, Val-DC-Lys, Valys Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, and Meth. In some modalities, P is Gly-Gly-Gly, Wing-Val, Wing-Wing, Wing-DAla, D-Wing-Wing or D-Wing-D-Wing. In some modalities, Q is -SO3M.

[0063] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 39 / 752 34 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 40 / 752 35 / 355 í Λ > hv > o> °< / z'x o> “V* ° h 1 w Μ ? Μ Ί iR H ? Z OOO OOOOOO ® / ” / \_ jH > / :H .a .ã . a ΟΜ oJ V / 0 4 °Μ° A 0 0..... Ο 0..... 0$ 0..... Μ r Μ r Μ r Ύ° Rr1 oRR* Η if N=c«~'-CBA 0 Η > 0 Ws J Η [] Ν—C^'CBA ο Η η2 > 5 WS JA Η π Ν—C—-CBA ο Η η2 > ws ; Η \ / „-Ν· Q n=C--cba 0-4 Η Υ < 0 ί > ws . ; Η Ν ^N=c^CBA 0-4 Η / > > ws . ; Η \ Ν —C^^CBA 0-4 Η Η2 7 > J Ws ; Petition 870260060475, dated 06 / 19 / 2026, p. 41 / 752 36 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 42 / 752 37 / 355 Ws; or or a pharmaceutically acceptable salt thereof, wherein the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be H; and when it is a single bond, X will be -H, and Y will be -OH or -SO3M.

[0064] Another aspect of the invention provides an immunoconjugate with the following formula: in which: CBA is the antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to the Jcb' group. Jcb' is a moiety formed by the reaction of an aldehyde group derived from Petition 870260060475, dated 06 / 19 / 2026, p. 43 / 752 38 / 355 of the oxidation of a 2-hydroxyethylamine portion at an N-terminus of said antibody or its antigen-binding fragment of the invention, or polypeptide thereof of the invention, and a reactive aldehyde group at Cys2, and is represented by the following formula: s 9 . H2H OeS1H=N'^s2S'HNA / s2π;n;n; . H2η s1f-c—?N H s2 ; s2 ; or where s1 is the site covalently bonded to CBA; and s2 is the site covalently bonded to Cys2; Cys2 is represented by the following formula: ; or a pharmaceutically acceptable salt thereof, where: Petition 870260060475, dated 06 / 19 / 2026, p. 44 / 752 39 / 355 The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M; M is H+ or a cation; Rx1 is a (C1-C6)alkyl group; Reé -H or a (C1-C6)alkyl; W' is -NRe', Re' is -(CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx2 is a (C1-C6)alkyl group; Li is represented by the following formula: in which: s3 is the site covalently linked to the Jcb' group; s4 is the site covalently linked to the -S- group in Cys2; Za2 is missing, -C(=O)-NR9-, or -NR9-C(=O)-; R9 is -H or a (C1-C3)alkyl group; Q is H, a charged substituent or an ionizable group; Ra1, Ra2, Ra3, Ra4, for each occurrence, are independently H or (C1-C3)alkyl; and q1 and r1 are each independently an integer from 0 to 10, provided that q1 and r1 are not both 0.

[0065] In certain modalities, -L1- is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 45 / 752 40 / 355 0; or ο or a pharmaceutically acceptable salt thereof, where R is H or SO3M.

[0066] In certain embodiments, Re is H or Me; and Rx1 is -(CH2)p(CRfRg)- and Rx2 is -(CH2)p-(CRfRg)-, where Rf and Rg are each independently -H or (C1-C4)alkyl; ep is 0, 1, 2 or 3. In certain embodiments, Rf and Rg are the same or different, and are selected from H and -Me.

[0067] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 46 / 752 41 / 355 ws Petition 870260060475, dated 06 / 19 / 2026, p. 47 / 752 42 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 48 / 752 43 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 49 / 752 44 / 355 Petition 870260060475, de 19 / 06 / 2026, pág. 50 / 752 45 / 355 0 A .s, HN XY\ / X ó rí TI JJ A^-N'···XX MeOXX Xí 0 0 A .s, HN X y\ x rS 1 / rí TIT X'^N., / 'x / 'θ^,θ MeO^ ^ ír 0 Λ '^'0'^-' ^5 / x Z' y 1 I H hz A / XΜi / · / <Λ I^NiAAOMth MeoXX- í J 0 0 L ^0. ,,S. / / o^-' N XsZ xW^xx J^^Nr^^QHe MeO' Zy. í JO ° Z o JX ,.S / - r^ \sz x xA Y 1 | HH 1 rWXCf í J ° 0 L r jx ,-s / / '-^'0'^-' ^-s-^ ' Λ^°^Χί MeO'^ / X- Cí ° ° XH Η Ί CBA s 1 ¥ o X CO2M o > X^-N^A^ ° ¥J JWs . JNHX ^NC -~-CBA s T π o X γ0Ο2Μ 0 an^A > >t^nx^¥ ° ¥J JWs . JH Xz X / N--C- / / wvwvwQgA Π H 0 7 ' WS JH aN\ _ Αχ / Xf N-- 0^ΛΛΛΛΛΛ^0β / \ Π H 0 <y>Ws JH \ / 'NX X / N--θ^ / νννννννν0β / \ Π H H2 0 V. ' J WS JH \ / N\ \ / X—c-TM—CBA Í1 H H2 0 <Y í ¥ | Ws J Petition 870260060475, dated 06 / 19 / 2026, p. 51 / 752 46 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 52 / 752 47 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 53 / 752 48 / 355 '-------- / =\ ' Γ\ If ο If Oa \ > Ολ . xo ui / o jV < jV ( °Λ=τχ i °; °”H'X °> °> m ? m / Z / > > y—% ( \\ / / / \ / / / oooooo ' ush ' N ' W · - « Λ l H Μ) u / Ju N2 H co |_| ^X·3 / 'C ° BA ° c- Xj ws ; Λ H |_| / 'N . N---^CBA N H2 HH r N—, rXX 5 OJ Ws J ou Λ O II H N--C CBA 'n^ h2 X Η 1 ' zY ( ^Ν-~^ ° XI > Ws J Petition 870260060475, dated 06 / 19 / 2026, p. 54 / 752 49 / 355 or a pharmaceutically acceptable salt thereof, wherein the double line = between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is H; and when it is a single bond, X is -H; and Y is -OH or -SO3M.

[0068] In certain embodiments, the double line — between N and C represents a double bond, X is absent and Y is -H.

[0069] In certain embodiments, the double line — between N and C represents a single bond, X is -H and Y is -SO3M. In certain embodiments, M is H+, Na+ or K+.

[0070] Another aspect of the invention provides an immunoconjugate with the following formula: ; in which: CBA is the antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to the Jcb' group; Jcb' is a portion formed by the reaction of an aldehyde group derived from the oxidation of a 2-hydroxyethylamine portion at an N-terminus of said antibody or its antigen-binding fragment of the invention, or polypeptide thereof of the invention, and a reactive aldehyde group at Cys3, and is represented by the following formula: JJJ where s1 is the site covalently bonded to CBA; and s2 is the site covalently bonded to Cys3; Cys3 is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 55 / 752 50 / 355 in which: m' is 1 or 2; Ri and R2 are each independently H or a (C1-C3)alkyl group; Li is represented by the following formula: Ra3 □ \ / a4s3 çV . .7 / \ / \ S νχ / Λ T\ Γ'^ Δ41Iζη RaiRa2Q where: s3 is the site covalently linked to the Jcb' group; s4 is the site covalently linked to the -S- group in Cys3; Za2 is missing, -C(=O)-NRg-, or -NRg-C(=O)-; R9 is -H or a (C1-C3)alkyl group; Q is H, a charged substituent or an ionizable group; Rai, Ra2, Ra3, Ra4, for each occurrence, are independently H or a (C1-C3)alkyl group; and qi and ri are each independently an integer from 0 to i0, provided that qi and ri are not both 0. [007i] In certain modalities, m' is ie Ri and R2 are both H. In certain modalities, m' is 2 and Ri and R2 are both Me.

[0072] In certain forms, -Li- is represented by the following formula: ; ; ; Petition 870260060475, dated 06 / 19 / 2026, p. 56 / 752 51 / 355 0; or a pharmaceutically acceptable salt thereof, where R is H or SO3M and M is H+ or a cation.

[0073] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 57 / 752 52 / 355 J or a pharmaceutically acceptable salt thereof; where DM is represented by the following formula: Me O

[0074] Another aspect of the invention provides an immunoconjugate with the following formula: CBaX'Jcb'—Cys4) ' 'wwhere: CBA is the antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to the Jcb' group. Jcb' is a portion formed by the reaction of an aldehyde group derived from the oxidation of a 2-hydroxyethylamine portion at an N-terminus of said antibody or its antigen-binding fragment of the invention, or polypeptide thereof of the invention, and a reactive aldehyde group at Cys4e is represented by the following formula: <, H2h s1|—C -N. s2 ; s2 s2 ; SK c H or where s1 is the site covalently linked to CBA; and s2 is the site Petition 870260060475, dated 06 / 19 / 2026, p. 58 / 752 53 / 355 covalently bonded to Cys4; Cys4 is represented by the following formula: Li' is represented by the following formula: in which: s3 is the site covalently linked to the Jcb' group; s4 is the site covalently linked to the -NMe- group in Cys4; Zbi and Zb2 are both absent, or one of Zbi and Zb2 is absent and the other is -CH2-O- or -O-CH2-; Zbi' and Zb2' are each independently absent, -CH2-O-, -OCH2-, -NRg-C(=O)-CH2-, or -CH2-C(=O)-NRg-; R9 is H or (C1-C3)alkyl; n1 and mi are each independently an integer of ia 6; one of Ei and E2 is -C(=O)-, and the other is -NRg-; or one of Ei and E2 is -C(=O)- or -NRg-, and the other is absent; P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; and Rb1, Rb2, Rb3, Rb4, Rb5 and Rb6, for each occurrence, are each independently either H or a (C1-C3)alkyl group.

[0075] In certain modalities, Rbi, Rb2, Rb3, Rb4, Rb5 and Rb6 are all Petition 870260060475, dated 06 / 19 / 2026, p. 59 / 752 54 / 355 H. In certain modalities, Rg is H.

[0076] In certain modalities, Zbi' and Zb2' are both absent; either Zbi' is -CH2-O-; and Zb2' is absent; or Zbi' is -CH2-C(=O)-NRg-; and Zb2' is -O-CH2- or absent.

[0077] In some embodiments, P is a peptide containing 2 to 5 amino acid residues. For example, P can be selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, AlaLys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-Ng-to-Trp-Arg, Phe-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), Gly-Leu (SEQ ID NO: 57), Leu-Ala-Leu (SEQ ID NO: 57). 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-A, Alag-A, Alag D-No-No, D-No-D-No, No-Meth and Met-No. In some modalities, P is Gly-Gly-Gly, Wing-Val, Wing-Wing, Wing-D-Wing, D-Wing-Wing and D-Wing-D-Wing.

[0078] In some embodiments, the immunoconjugate is represented by the following formula: Petition 870260060475, of 19 / 06 / 2026, p. 60 / 752 55 / 355 j H ?n9 H ο CBA-j-CH2--N HO HO Iws· j Ws. ; ws. j Ws· j Petition 870260060475, dated 06 / 19 / 2026, p. 61 / 752 56 / 355 ws. j WS. J ws. J or a pharmaceutically acceptable salt thereof, where DM is represented by the following structural formula: Me O

[0079] Another aspect of the invention provides an immunoconjugate represented by the following formula: CBA-(—Cyc1) 'Zwcem que: Petition 870260060475, dated 06 / 19 / 2026, p. 62 / 752 57 / 355 CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to CyC1 through a cysteine ​​residue; WC is 1 or 2; CyC1 is represented by the following formula: or a pharmaceutically acceptable salt thereof, where: The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M, and M will be H+ or a cation; R5 is -H or a (C1-C3)alkyl group; Petition 870260060475, dated 06 / 19 / 2026, p. 63 / 752 58 / 355 P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; Ra and Rb, for each occurrence, are independently -H, (C1C3)alkyl, or a charged substituent or an ionizable group Q; W' is -NRe', Re' is -(CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx3 is a (C1-Ce)alkyl group; and, LC is represented by s1 is the site covalently bonded to CBA, and s2 is the site covalently bonded to the -C(=O)- group in CyC1; where: R19 and R20, for each occurrence, are independently either -H or a (C1C3)alkyl; m is an integer between 1 and 10; and Rh is -H or a (C1-C3)alkyl group.

[0080] In certain modalities, Ra and Rb are both H; and R5 is H or Me.

[0081] In certain embodiments, P is a peptide containing 2 to 5 amino acid residues. For example, P may be selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, AlaLys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N9-tosyl-Arg, PheN9-nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-LeuAla-Leu (SEQ ID NO: 57), Gly-Phe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-D-Arg, AlaAla, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met and Met-Ala. In certain Petition 870260060475, dated 06 / 19 / 2026, p. 64 / 752 In 59 / 355 modes, P is Gly-Gly-Gly, Wing-Val, Wing-Wing, Wing-D-Wing, D-Wing-Wing, or D-Wing-D-Wing. In certain modes, Q is -SO3M.

[0082] In certain modalities, R19 and R20 are both H; in is an integer from 1 to 6.

[0083] In certain modalities, -LC- is represented by the following formula:

[0084] In certain forms, the immunoconjugate is represented by the following formula: toilet or Petition 870260060475, dated 06 / 19 / 2026, p. 65 / 752 60 / 355 ; or a pharmaceutically acceptable salt thereof, wherein the double line = between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be H; and when it is a single bond, X will be -H, and Y will be -OH or -SO3M.

[0085] Another aspect of the invention provides an immunoconjugate represented by the following formula: CBA-(—CyC2) ' 'wc, where: CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to CyC2 via a cysteine ​​residue; WC is 1 or 2; CyC2 is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 66 / 752 61 / 355 or a pharmaceutically acceptable salt thereof, where: The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M, and M will be H+ or a cation; Rx1 is a (C1-C6)alkyl group; Reé -H or a (C1-C6)alkyl; W' is -NRe'; Re' is -(CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx2 is a (C1-C6)alkyl group; LC' is represented by the following formula: the ; ; in which: s1 is the site covalently bonded to CBA and s2 is the site covalently bonded to CBA. Petition 870260060475, dated 06 / 19 / 2026, p. 67 / 752 62 / 355 linked to the -S- group in CyC2; Z is -C(=O)-NR9-, or -NR9-C(=O)-; Q is -H, a charged substituent, or an ionizable group; R9, R10, R11, R12, R13, R19, R20, R21 and R22, for each occurrence, are independently either -H or a (C1-C3)alkyl group; qer, for each occurrence, is independently an integer between 0 and 10; Men are, each one independently, an integer between 0 and 10; Rhé -H or a (C1-C3)alkyl; and P' is an amino acid residue or a peptide containing 2 to 20 amino acid residues.

[0086] In some embodiments, P' is a peptide containing 2 to 5 amino acid residues. For example, P' can be selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, AlaLys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N9-Arg, Phe-N9-Arg Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), Gly-Leu (SEQ ID NO: 57), Leu-Ala-Leu (SEQ ID NO: 57). 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-A, Alag-A, Alag D-No-No, D-No-D-No, No-Meth and Met-No. In some modalities, P' is Gly-Gly-Gly, Wing-Val, Wing-Wing, Wing-D-Wing, D-Wing-Wing or D-Wing-D-Wing.

[0087] In some embodiments, the -LC'- immunoconjugate is represented by the following formula: Petition 870260060475, of 19 / 06 / 2026, p. 68 / 752 63 / 355 ; Your

[0088] In certain embodiments, Re is H or Me; Rx1 is -(CH2)p-(CRfRg), and Rx2 is -(CH2)p-(CRfRg)-, where Rf and Rg are each independently -H or a (C1-C4)alkyl group; ep is 0, 1, 2 or 3. In certain embodiments, Rf and Rg are the same or different, and are selected from -H and -Me.

[0089] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 69 / 752 64 / 355 Petition 870260060475, dated 06 / 19 / 2026, pp. 70 / 752 65 / 355 J or a pharmaceutically acceptable salt thereof, wherein the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is Hj and when it is a single bond, X is -H, and Y is -OH or -SO3M.

[0090] In certain embodiments, the double line — between N and C represents a double bond, X is absent and Y is -H.

[0091] In certain embodiments, the double line — between N and C represents a single bond, X is -H and Y is -SO3M. In certain embodiments, M is H+, Na+ or K+.

[0092] Another aspect of the invention provides an immunoconjugate with the following formula: CBA-(—Cyc3) 'Zwcem que: CBA is an antibody or its antigen-binding fragment of the invention, or its polypeptide of the invention, covalently linked to CyC3 through a cysteine ​​residue; WC is 1 or 2; Petition 870260060475, dated 06 / 19 / 2026, pp. 71 / 752 66 / 355 CyC3 is represented by the following formula: in which: m' is 1 or 2; Ri and R2 are each independently either -H or a (C1-C3) alkyl group; LC' is represented by the following formula: the ; ; in which: s1 is the site covalently linked to CBA and s2 is the site covalently linked to the -S- group in CyC3; Z is -C(=O)-NR9-, or -NR9-C(=O)-; Q is H, a charged substituent or an ionizable group; R9, R10, R11, R12, R13, R19, R20, R21 and R22, for each occurrence, are independently either -H or a (C1-C3)alkyl group; qer, for each occurrence, is independently an integer between 0 and 10; Men are, each one independently, an integer between 0 and 10; Rh is -H or a (C1-C3)alkyl group; and P' is an amino acid residue or a peptide containing 2 to 20 amino acid residues. Petition 870260060475, of 19 / 06 / 2026, p. 72 / 752 67 / 355

[0093] In some embodiments, P' is a peptide containing 2 to 5 amino acid residues. For example, P' is selected from Gly-GlyGly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, PheCit, Leu-Cit, Lle-Cit, Trp, Cit, Phe-Ala, Phe-N9-tosyl-Arg, N-Arg, ni Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-AlaLeu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), Leu-Leu (SEQ ID NO: 57). 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-ValArg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-Arg, Ala-D-A, Ala, Ala D-No-No, D-No-D-No, No-Meth and Met-No. In some modalities, P' is Gly-Gly-Gly, Wing-Val, Wing-Wing, Wing-D-Wing, D-Wing-Wing or D-Wing-D-Wing.

[0094] In some embodiments, -LC'- is represented by the following formula: where M is H+ or a cation.

[0095] In certain modalities, m' is 1 and Ri and R2 are both H. In certain modalities, m' is 2 and R1 and R2 are both Me.

[0096] In certain forms, the immunoconjugate is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, pp. 73 / 752 68 / 355 JWc; or or a pharmaceutically acceptable salt thereof, where DM is a drug portion represented by the following formula:

[0097] Another aspect of the invention provides a pharmaceutical composition comprising the antibody or its antigen-binding fragment of the invention, or the polypeptide of the invention, or the immunoconjugate of the invention, and a pharmaceutically acceptable carrier.

[0098] Another aspect of the invention provides a method for inhibiting the growth of a cell expressing CD123, comprising contacting the cell with the antibody or its antigen-binding fragment of the invention, or the polypeptide of the invention, or the immunoconjugate of the invention, or the pharmaceutical composition of the invention.

[0099] In certain modalities, the cell is a tumor cell. In Petition 870260060475, dated 06 / 19 / 2026, pp. 74 / 752 69 / 355 In certain modalities, the cell is either a leukemia cell or a lymphoma cell.

[00100] Another aspect of the invention provides a method for treating a subject with cancer, in which cancer cells express CD123, the method comprising administering to said subject a therapeutically effective amount of the antibody or antigen-binding fragment thereof, or the polypeptide of the invention, or the immunoconjugate of the invention, or the pharmaceutical composition of the invention.

[00101] In certain modalities, the cancer or proliferative cell disorder is leukemia or lymphoma. In certain modalities, the cancer or proliferative cell disorder is selected from the group consisting of: acute myeloid leukemia (AML); chronic myeloid leukemia (CML); acute lymphoblastic leukemia (ALL), including B-cell lineage acute lymphoblastic leukemia (B-ALL); chronic lymphocytic leukemia (CLL); hairy cell leukemia (HCL); myelodysplastic syndrome; basic plasmacytoid DC neoplasm leukemia (BPDCN); non-Hodgkin lymphomas (NHL), including mantle cell lymphoma; and Hodgkin leukemia (HL). In certain modalities, the cancer is acute myeloid leukemia (AML). In certain modalities, the cancer is B-cell acute lymphoblastic leukemia (B-ALL).

[00102] Another aspect of the invention provides a method for treating a cellular proliferative disorder in a subject, wherein the cellular proliferative disorder cells express CD123, the method comprising administering to said subject a therapeutically effective amount of the antibody or its antigen-binding fragment of the invention, or the polypeptide of the invention, or the immunoconjugate of the invention, or the pharmaceutical composition of the invention, in an amount sufficient to treat said cellular proliferative disorder. Petition 870260060475, dated 06 / 19 / 2026, pp. 75 / 752 70 / 355

[00103] It is contemplated that any embodiment described in this document, including those described only in one aspect of the invention (but not in others or not repeated in others), and those described only in the Examples, may be combined with any one or more other embodiments of the invention, unless explicitly denied or inapplicable. BRIEF DESCRIPTION OF THE FIGURES

[00104] FIG. 1 shows the inhibition of IL3-dependent proliferation of TF-1 cells by chimeric CD123-6 antibody (chCD123-6) and its CDR-grafted huCD123-6 antibodies (huCD123-6Gv4.6 and huCD123-6Gv4.7).

[00105] FIGS. 2A and 2B show that three murine anti-CD123 antibodies (muCD123-3, -6 and -14) inhibit IL3-dependent proliferation of TF-1 cells at least as well as 7G3. FIG. 2A shows the inhibition of TF-1 cells cultured in the presence of IL-3 (1 ng / mL) by the various anti-CD123 antibodies, including CD123-binding control antibodies 7G3, 6H6 and 9F5. FIG. 2B shows the inhibition of TF-1 cells cultured in the presence of GM-CSF (2 ng / mL) by the same anti-CD123 antibodies.

[00106] FIG. 3 shows that murine anti-CD123 antibodies muCD123-3, -6 and -14 inhibit IL-3-dependent proliferation (1 ng / mL) of TF-1 cells in a dose-dependent manner and to a greater degree than antibody 7G3. muCD123-16 is a negative control anti-CD123 antibody that binds to CD123 but does not inhibit IL-3-dependent proliferation of TF-1 cells.

[00107] FIGS. 4A and 4B show that murine antibodies muCD123-3, -6 and -14 have a higher binding affinity to CD123-positive AML cells than antibody 7G3 on CD123-expressing TF-1 (FIG. 4A) and HNT-34 (FIG. 4B) cells.

[00108] FIGS. 5A and 5B show that anti-CD-123 antibodies Petition 870260060475, dated 06 / 19 / 2026, pp. 76 / 752 71 / 355 chimeric antibodies, chCD123-3, -6, and -14, retain high binding affinity of their murine counterparts, using HNT-34 cells (FIG. 5A) or the MOLM-13 cell line (FIG. 5B) of CD123-positive acute myeloid leukemia (AML). The chimeric antibody chKTI, which does not bind CD123, was included as a negative control.

[00109] FIG. 6 shows that chimeric chCD1233, -6 and -14 anti-CD123 antibodies maintain the functional activity of their murine counterparts, as evidenced by their ability to inhibit IL-3-dependent proliferation of TF-1 cells. A non-functional chimeric anti-CD123 antibody (chCD123-18) that binds CD123 but does not inhibit IL-3-dependent proliferation of TF-1 cells was included as a negative control.

[00110] FIG. 7A shows that the murine (muCD123-6), chimeric (chCD123-6), and CDR-grafted huCD123-6 (huCD1236Gv4.7S2 and huCD123-6Gv4.7S3) antibodies have higher affinity than 7G3 for HNT-34 cells expressing CD123. The chimeric antibody chKTI, which does not bind CD123, was included as a negative control. FIGS. Figures 7B and 7C show that conjugation of huCD123-6Gv4.7S3 or the Gv4.7 antibody to compounds D1 or D2 via Lys-, Ser-, or Cys- binding only moderately affected the binding affinities of these ADC conjugates, namely huCD123-6Gv4.7S3-SeriMab-sD1 bound to Ser (see structure in FIG. 17) and huCD123-6Gv4.7S3-SeriMabD8 and the huCD123-6Gv4.7S3-sSPDB-D1 bound to Lys and huCD123-6Gv4.7S3-D2 in FIG. 7B; and the huCD123-6Gv4.7-CysMab-D4 and huCD123-6Gv4.7-CysMab-D5 linked to Cys in FIG. 7C. In FIG. 7C, the unconjugated huCD123-6Gv4.7 antibody has a heavy chain sequence of SEQ ID NO: 54, where Xaa is Val.The conjugates with S3-SeriMab have cytotoxin binding (in this case, the indolinobenzodiazepine compounds or IGN in this document) through an oxidized N-terminal Ser light chain. The conjugates... Petition 870260060475, dated 06 / 19 / 2026, pp. 77 / 752 72 / 355 with CysMab have cytotoxin binding (in this case, IGN compounds) through a molecularly modified Cys in the heavy chain (i.e., Cys corresponds to the 5th to last Cys in SEQ ID NO: 54).

[00111] FIG. 8A shows that chimeric (chCD123-6) and CDR-grafted huCD123-6 antibodies (huCD123-6Gv4.7S2 and huCD1236Gv4.7S3) inhibit IL-3-dependent proliferation of TF-1 cells better than 7G3 antibodies. The inhibition is IL-3-dependent, since these antibodies had no inhibitory effect when the cells grew in the presence of GM-CSF (Figure 8B).

[00112] FIG. 9A shows the expression constructs of the IL-3Ra extracellular domain (CD123) and chimeric receptor proteins comprising IL-3Ra (gray) and GMRa (white) domains. FIG. 9B shows that the CD123-6 antibody binds primarily to the CRM domain of IL-3Rα (residues 101-306). FIG. 9C shows that the CD1233 antibody binds primarily to the CRM domain of IL-3Rα (residues 101-306). FIG. 9D shows that the CD123-14 antibody binds exclusively to the N-terminal domain of IL-3Rα (residues 1-100). FIG. 9E shows that the 7G3 antibody binds exclusively to the N-terminal domain of IL-3Rα (residues 1-100). Figure 9F shows that antibody 6H6 binds exclusively to the N-terminal domain of IL-3Rα (residues 1-100). Figure 9G shows that antibody 9F5 binds exclusively to the N-terminal domain of IL-3Rα (residues 1-100).

[00113] FIG. 10 demonstrates that the Maytansinoid DM1 conjugate of the coated huCD123-6Rv1.1 antibody, huCD123-6Rv1.1-CX1-1-DM1, exhibits OCI-AML4-dependent cytotoxicity from the CD123-expressing AML cell line independent of growth factor. The cytotoxicity is CD123-dependent, as evidenced by the ability of excess unconjugated huCD123-6 antibody (500 nM) to block cytotoxicity.

[00114] FIG. 11A shows in vitro cytotoxicity of the various Petition 870260060475, dated 06 / 19 / 2026, pp. 78 / 752 73 / 355 lysine-bound huCD123-6Rv1.1-IGN conjugates in multiple CD123-positive malignant cell lines of different origins.

[00115] FIG. 11B shows the in vitro cytotoxicity of various lysine- or cysteine-linked huCD123-6-IGN conjugates in multiple CD123-positive B-ALL cell lines. Unlinked KTI-based conjugates are included as negative controls.

[00116] FIG. 11C shows that the various Lys- or Cys-bound IGN compounds are highly active in the P-gp (P-glycoprotein) positive AML cell lines Kasumi-3 and MOLM-1. Control curves with open data points are produced in the presence of excess unconjugated corresponding huCD123 antibodies.

[00117] FIG. 11D shows that almost all of the various Lys- or Cys-linked CD123-IGN conjugates of the invention kill 90% of AML progenitor cells from samples of 9 AML patients at nM or sub-nM concentrations.

[00118] FIG. 11E shows that the Cys-linked huCD123-6Gv4.7CysMab-D5 conjugate kills normal blood cells at concentrations that are >100 times higher than those required to kill AML progenitors. In comparison, Mylotarg does not exhibit this preferential killing effect.

[00119] FIGS. 12A and 12B show in vitro cytotoxicity of the various lysine-linked huCD123-6Rv1.1-IGN conjugates in primary cells from AML patients. The result of a typical CFU test for a primary patient sample is shown in FIG. 12A. FIG. 12B shows the IC90 values ​​for all AML patient samples treated with the conjugates.

[00120] FIGS. 13A-13C show that the CysMab IGN conjugate of huCD123-6 (huCD123-6Gv4.6-CysMab-D5, filled black circle) is at least as active as the lysine-bound conjugate (huCD123-6Gv4.6-D2, filled black square) of the same antibody. Petition 870260060475, dated 06 / 19 / 2026, pp. 79 / 752 74 / 355 in relation to EOL-1 from AML cell line (FIG. 13A), KOPN-8 from B-ALL cell line (FIG. 13B) and MOLM-1 from CML cell line (FIG. 13C). The dashed curves connecting open data points in each figure represent the activity of the respective conjugates (i.e., open circle for huCD123-6Gv4.6-CysMab-D5 and open square for huCD123-6Gv4.6-D2) in the presence of a blocking concentration (500 nM) of the unconjugated chCD123-6 antibody.

[00121] FIGS. 14A-14C show that huCD123-6 SeriMab (huCD123-6Rv1.1S2-SeriMab-D8, filled black circle) is at least as active as the lysine-bound conjugate (huCD123-6Rv1.1D2, filled black triangle) of the same antibody in SHI-1 from AML cell lines (FIG. 14A) and HNT-34 (FIG. 14B), as well as MOLM-1 from CML cell line (FIG. 14C). The dashed curves connecting open data points in each figure represent the activity of the respective conjugates (i.e., open circle for huCD123-6Rv1.1S2-SeriMab-D8 and open descending triangle for huCD123-6Rv1.1-D2) in the presence of a blocking concentration (500 nM) of the unconjugated huCD123-6 antibody.

[00122] FIG. 15 shows a schematic drawing to illustrate the general steps that can be used to synthesize a Serlinkage conjugate of the invention.

[00123] FIG. 16 shows a schematic drawing to illustrate the general steps that can be used to synthesize a Serlinkage conjugate of the invention.

[00124] FIG. 17 shows a schematic drawing to illustrate the general steps that can be used to synthesize a Serlinkage conjugate of the invention.

[00125] FIG. 18 shows that the huCD123-6Gv4.7CysMab-D5 conjugate associated with Cys has greater activity than gemtuzumab. Petition 870260060475, dated 06 / 19 / 2026, page 80 / 752 75 / 355 ozogamicin (GO) (also known as Mylotarg) in samples from unselected AML patients.

[00126] FIG. 19 shows that the Cys-linked huCD123-6Gv4.7CysMab-D5 conjugate kills normal progenitor cells at concentrations that are >100 times higher than those required to kill AML progenitors. In comparison, Mylotarg and huCD1236G4.7-CysMab-D5' (DNA crosslinking D5' ADC) do not exhibit this preferential killing effect.

[00127] FIG. 20 shows in vivo efficacy of CD123-IGN conjugates in the AML MV4-11 subcutaneous mouse model.

[00128] FIG. 21 shows that the huCD123-6Gv4.7CysMab-D5 conjugate linked to Cys is highly active in several CD123-positive AML cell lines with few prognostic factors.

[00129] FIG. 22 shows in vivo bioluminescence imaging of mice treated with huCD123-6Gv4.7CysMab-D5 conjugate compared with vehicle-treated and control mice on day 26. Treatment with the conjugate significantly reduces tumor burden in mice.

[00130] FIG. 23 shows the prolonged survival treatment of huCD123-6Gv4.7-CysMab-D5 conjugate 6 / 6 mice compared with vehicle-treated and control mice.

[00131] FIG. 24 shows that incubation of MV4-11 cells with huCD123-6Gv4.7-CysMab-D5 conjugate leads to DNA damage, S-phase cell cycle arrest, and apoptosis-mediated cell death.

[00132] FIG. 25 shows the in vivo efficacy of CD123IGN conjugates in the Molm-13 AML dissemination model.

[00133] FIG. 26 shows the in vivo efficacy of CD123IGN conjugates in the subcutaneous EOL-1 model.

[00134] FIG. 27 shows the in vivo efficacy of the huCD123CysMab-D5 conjugate at various doses in the EOL-1 subcutaneous model. Petition 870260060475, dated 06 / 19 / 2026, page 81 / 752 76 / 355

[00135] FIG. 28 shows the in vivo efficacy of the huCD123CysMab-D5 conjugate compared with the corresponding payload-free drug form (FGN849 or D5), naked antibody, control, cytarabine, and azacitidine in the EOL-1 subcutaneous model.

[00136] FIG. 29 shows the in vivo efficacy of CD123IGN conjugates in the disseminated MV4-11 AML model.

[00137] FIG. 30 shows in vivo efficacy of CD123-IGN conjugates in the MV4-11 AML subcutaneous model.

[00138] FIG. 31 shows treatment with prolonged survival of huCD123-CysMab-D5 conjugate in mice compared with vehicle-treated and control mice.

[00139] FIG. 32 shows in vivo tolerability of huCD123-CysMab-D5 and huCD123-SeriMab-sD1 conjugates in mice.

[00140] FIG. 33 shows in vivo tolerability of the D2 conjugate bound to huCD123-lysine in mice. DETAILED DESCRIPTION OF THE INVENTION 1. Definitions

[00141] To facilitate understanding of the present invention, a series of terms and phrases are defined below.

[00142] The terms human IL-3Ra, Interleukin-3 receptor alpha, or CD123, as used alternatively in this document, refer to any native (human) IL-3Rα or CD123, unless otherwise indicated. The CD123 protein is an interleukin-3 specific subunit of a heterodimeric cytokine receptor (IL-3 receptor or IL-3R). IL-3R consists of a ligand-specific alpha subunit and a common signal transducer beta subunit (also known as CD131) shared by receptors for interleukin 3 (IL3), colony-stimulating factor 2 (CSF2 / GM-CSF), and interleukin 5 (IL5). The binding of CD123 / IL-3Rα to IL3 is dependent on the beta subunit. The beta subunit is activated by ligand binding and Petition 870260060475, dated 06 / 19 / 2026, p. 82 / 752 77 / 355 is required for the biological activities of IL3.

[00143] All of the above terms for CD123 may refer to a protein or a nucleic acid sequence as indicated in this document. The term CD123 / IL-3Ra encompasses full-length, unprocessed CD123 / IL-3Rα as well as any form of CD123 / IL-3Rα that results from processing within the cell. The term also encompasses naturally occurring variants of the CD123 / IL-3Rα protein or nucleic acid, for example, splice variants, allelic variants, and isoforms. The CD123 / IL-3Rα polypeptides and polynucleotides described in this document may be isolated from a variety of sources, such as human tissue types or from other sources, or prepared by synthetic or recombinant methods.Examples of CD123 / IL-3Rα sequences include, but are not limited to, NCBI reference numbers NP_002174 & NM_002183 (protein and nucleic acid sequences for human CD123 variant 1) and NP_001254642 and NM_001267713 (protein and nucleic acid sequences for human CD123 variant 2).

[00144] The term antibody means an immunoglobulin molecule that specifically recognizes and binds to a target, such as a protein, polypeptide, peptide, carbohydrate, polynucleotide, lipid, or combination thereof, through at least one antigen recognition site within the variable region of the immunoglobulin molecule. In this document, the term antibody encompasses intact polyclonal antibodies, intact monoclonal antibodies, antibody fragments (such as Fab, Fab', F(ab')2 and Fv fragments), single-chain Fv mutants (scFv), multispecific antibodies, such as bispecific antibodies, chimeric antibodies, humanized antibodies, human antibodies, fusion proteins comprising an antigen-determining portion of an antibody, and any other immunoglobulin molecule. Petition 870260060475, dated 06 / 19 / 2026, p. 83 / 752 78 / 355 modified comprising an antigen recognition site provided that the antibodies exhibit the desired biological activity. An antibody may be from any of the five major immunoglobulin classes: IgA, IgD, IgE, IgG, and IgM, or subclasses (isotypes) thereof (e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2), based on the identity of their constant heavy chain domains referred to as alpha, delta, epsilon, gamma, and mu, respectively. Different immunoglobulin classes have different and known subunit structures and three-dimensional configurations. Antibodies may be naked or conjugated to other molecules, such as toxins, radioisotopes, etc.

[00145] In some embodiments, an antibody is a non-naturally occurring antibody. In some embodiments, an antibody is purified from natural components. In some embodiments, an antibody is produced by recombination. In some embodiments, an antibody is produced by a hybridoma.

[00146] A blocking antibody or an antagonist antibody is one that inhibits or reduces the biological activity of the antigen it binds to, such as CD123 / IL-3Ra. In a given embodiment, blocking antibodies or antagonist antibodies substantially or completely inhibit the biological activity of the antigen. Desirably, the biological activity is reduced by 10%, 20%, 30%, 50%, 70%, 80%, 90%, 95% or even 100%.

[00147] The term anti-CD123 antibody, anti-IL-3Rα antibody, or an antibody that (specifically) binds to CD123 / IL-3Ra refers to an antibody that is capable of binding CD123 / IL-3Ra with sufficient affinity such that the antibody is useful as a diagnostic and / or therapeutic agent in the induction of CD123 / IL-3Ra. Unless otherwise specified, the extent of binding of an anti-CD123 / IL-3Ra antibody to an unrelated non-CD123 / IL-3Ra protein is Petition 870260060475, dated 06 / 19 / 2026, p. 84 / 752 79 / 355 less than approximately 10% of the antibody binding to CD123 / IL-3Ra as measured, for example, by a radioimmunoassay (RIA). In certain embodiments, an antibody that binds to CD123 / IL-3Ra has a dissociation constant (Kd) of < 0.5 nM, < 0.3 nM, < 0.1 nM, < 0.05 nM, or < 0.01 nM. In one embodiment, the anti-CD123 / IL-3Ra antibody does not bind common beta-chain CD131. In one embodiment, the anti-CD123 / IL-3Ra antibody does not bind to the same CD123 epitope that is bound by known and commercially available CD123 antibodies, such as 7G3 (mouse IgG2a), 6H6 (mouse IgG1), and 9F5 (mouse IgG1) (Sun et al., Blood 87(1): 8392, 1996).

[00148] The anti-CD123 / IL-3Ra antibody sequences and their antigen-binding fragments of the invention are provided in Tables 1-6 below. The nomenclature for the various antibodies and immunoconjugates of the invention is provided separately below.

[00149] The term antibody fragment refers to a portion of an intact antibody and refers to the antigen-determining variable regions of an intact antibody. Examples of antibody fragments include, but are not limited to, Fab, Fab', F(ab')2 and Fv fragments, linear antibodies, single-chain antibodies, and multispecific antibodies formed from antibody fragments. The term antigen-binding fragment of an antibody includes one or more fragments of an antibody that retain the ability to bind specifically to an antigen. The antigen-binding function of an antibody has been shown to be performed by certain fragments of a full-length antibody. Examples of binding fragments encompassed by the term antigen-binding fragment of an antibody include (without limitation): (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CH1 domains (e.g., a papain-digested antibody produces Petition 870260060475, dated 06 / 19 / 2026, p. 85 / 752 80 / 355 three fragments: two antigen-binding Fab fragments and one non-antigen-binding Fc fragment); (ii) an F(ab')2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge in the hinge region (e.g., a pepsin-digested antibody produces two fragments: a bivalent antigen-binding F(ab')2 fragment and a non-antigen-binding pFc' fragment) and its related monovalent F(ab') unit; (iii) an Fd fragment consisting of the Vh and Chi domains (i.e., the portion of the heavy chain that is included in Fab); (iv) an Fv fragment consisting of the Vl and Vh domains of a single arm of an antibody, and related disulfide-linked Fv; (v) a dAb (domain antibody) or sdAb (single domain antibody) fragment (Ward et al., Nature 341:544-546, 1989), consisting of a Vh domain; and (vi) and an isolated complementarity-determining region (CDR).

[00150] A monoclonal antibody refers to a homogeneous population of antibodies involved in highly specific recognition and binding of a single antigenic determinant, or epitope. This contrasts with polyclonal antibodies, which typically include different antibodies directed against different antigenic determinants. The term monoclonal antibody encompasses intact, full-length monoclonal antibodies as well as antibody fragments (such as Fab, Fab', F(ab%Fv), single-strand mutants (scFv), fusion proteins comprising an antibody portion, and any other modified immunoglobulin molecule comprising an antigen recognition site. Furthermore, monoclonal antibody refers to such antibodies made in various ways, including but not limited to, hybridoma, phage selection, recombinant expression, and transgenic animals.

[00151] The term humanized antibody refers to forms of non-human antibodies (e.g., murine) that are antibody chains. Petition 870260060475, dated 06 / 19 / 2026, p. 86 / 752 81 / 355 specific immunoglobulin, chimeric immunoglobulins or their fragments containing minimal non-human sequences (e.g., murine). Typically, humanized antibodies are human immunoglobulins in which residues of the complementarity-determining region (CDR) are replaced by CDR residues from a non-human species (e.g., mouse, rat, rabbit, hamster) that have the desired specificity, affinity, and capability (Jones et al., Nature 321:522-525, 1986; Riechmann et al., Nature). 332:323-327, 1988; Verhoeyen et al., Science 239:1534-1536, 1988).

[00152] In some cases, the residues of the Fv framework region (FR) of a human immunoglobulin are replaced by corresponding residues in a non-human species antibody that has the desired specificity, affinity, and capacity. The humanized antibody may be further modified by replacing additional residues in the Fv framework region and / or within the replaced non-human residues to refine and optimize the antibody's specificity, affinity, and / or capacity. Generally, the humanized antibody will comprise substantially all of at least one, and typically two or three, variable domains containing all or substantially all of the CDR regions that correspond to the non-human immunoglobulin, whereas all or substantially all of the FR regions are those of a consensus sequence of the human immunoglobulin.The humanized antibody may also comprise at least a portion of an immunoglobulin (Fc) constant region or domain, typically that of a human immunoglobulin. Examples of methods used to generate humanized antibodies are described in U.S. Patents 5,225,539 and 5,639,641, Roguska et al., Proc. Natl. Acad. Sci. USA 91(3): 969-973, 1994; and Roguska et al., Protein Eng. 9(10): 895-904, 1996 (all incorporated herein by reference). In some. Petition 870260060475, dated 06 / 19 / 2026, p. 87 / 752 In 82 / 355 embodiments, a humanized antibody is a coated antibody. In some embodiments, a humanized antibody is a CDR-grafted antibody.

[00153] A variable region of an antibody refers to the variable region of the antibody light chain or the variable region of the antibody heavy chain, either alone or in combination. The variable regions of the heavy and light chains consist of four framework regions (FRs) connected by three complementarity-determining regions (CDRs), also known as the hypervariable regions. The CDRs in each chain are held together in close proximity by the FRs and, with the CDRs of the other chain, contribute to the formation of the antigen-binding site of the antibodies. There are at least two techniques for determining CDRs: (1) an approach based on cross-species sequence variability (i.e., Kabat et al. Sequences of Proteins of Immunological Interest, 5th ed., 1991, National Institutes of Health, Bethesda Md.); and (2) an approach based on crystallographic studies of antigen-antibody complexes (Al-lazikani et al., J. Molec. Biol. 273:927948, 1997).Furthermore, combinations of these two approaches are sometimes used in the technique to determine the CDRs.

[00154] The Kabat numbering system is generally used when referring to a residue in the variable domain (approximately residues 1-107 of the light chain and residues 1-113 of the heavy chain) (e.g., Kabat et al., Sequences of Immunological Interest, 5th Ed., Public Health Service, National Institutes of Health, Bethesda, Md. (1991)).

[00155] The amino acid position numbering as in Kabat refers to the numbering system used for variable heavy chain domains or variable light chain domains in the antibody compilation in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed., Public Health Service, National Institutes of Health, Petition 870260060475, dated 06 / 19 / 2026, page 88 / 752 83 / 355 Bethesda, Md. (1991) (incorporated herein by reference). Using this numbering system, the actual linear amino acid sequence may contain fewer or more amino acids corresponding to a shortening of, or insertion into, a variable domain FR or CDR. For example, a heavy chain variable domain may include a single amino acid insertion (residue 52a according to Kabat) after residue 52 of H2 and inserted residues (e.g., residues 82a, 82b, and 82c, etc. according to Kabat) after residue 82 of the heavy chain FR. The Kabat numbering of residues can be determined for a given antibody by alignment in homology regions of the antibody sequence with a standard numbered Kabat sequence. Instead, Chothia refers to the location of structural loops (Chothia and Lesk J. Mol. Biol. 196:901-917, 1987).The end of the Chothia CDR-H1 loop when numbered using the Kabat numbering convention varies between H32 and H34, depending on the loop length. This is because the Kabat numbering scheme places the insertions at H35A and H35B – if neither 35A nor 35B is present, the loop ends at 32; if only 35A is present, the loop ends at 33; if both 35A and 35B are present, the loop ends at 34. The AbM hypervariable regions represent a compromise between Kabat CDRs and Chothia structural loops, and are used by Oxford Molecular's AbM antibody modeling software. Kabat AbM Chiothia Handle L1 L24-L34 L24-L34 L24-L34 L2 L50-L56 L50-L56 L50-L56 L3 L89-L97 L89-L97 L89-L97 H1 H31-H35B H26-H35B H26-H32..34 (Kabat Numbering) H1 H31-H35 H26-H35 H26-H32 Petition 870260060475, dated 06 / 19 / 2026, page 89 / 752 84 / 355 (Chotia Numbering) H2 H50-H65 H50-H58 H52-H56 H3 H9S-H102 H95-H102 H95-H102

[00156] The term human antibody means an antibody produced by a human or an antibody with an amino acid sequence corresponding to an antibody produced by a human using any technique known in the art. In certain embodiments, the human antibody has no non-human sequence. This definition of a human antibody includes intact or full-length antibodies, or antigen-binding fragments thereof.

[00157] The term chimeric antibodies refers to antibodies in which the amino acid sequence of the immunoglobulin molecule is derived from two or more species. Typically, the variable region of the light and heavy chains corresponds to the variable region of antibodies derived from one mammalian species (e.g., mouse, rat, rabbit, etc.) with the desired specificity, affinity, and capacity, while the constant regions are homologous to sequences in antibodies derived from another (usually human) species to avoid or reduce the chance of provoking an immune response in that species (e.g., human). In certain embodiments, the chimeric antibody may include an antibody or its antigen-binding fragment comprising at least one human heavy and / or light chain polypeptide, such as, for example, an antibody comprising murine light chain and human heavy chain polypeptides.

[00158] The terms epitope or antigenic determinant are used interchangeably in this document and refer to the portion of an antigen capable of being recognized and specifically bound by a particular antibody. When the antigen is a polypeptide, epitopes can be formed by either contiguous amino acids or by... Petition 870260060475, dated 06 / 19 / 2026, p. 90 / 752 85 / 355 non-contiguous amino acids juxtaposed by a tertiary folding of a protein. Epitopes formed from contiguous amino acids are normally retained after protein denaturation, while epitopes formed by tertiary folding are normally lost after protein denaturation. An epitope typically includes at least 3, and more commonly, at least 5 or 8-10 amino acids in a single spatial conformation.

[00159] Binding affinity generally refers to the strength of the sum total of non-covalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless otherwise indicated, as used in this document, binding affinity refers to intrinsic binding affinity reflecting a 1:1 interaction between the members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (Kd) or the half-maximal effective concentration (EC50). Affinity can be measured by common methods known in the art, including those described in this document.Low-affinity antibodies generally bind to the antigen slowly and tend to dissociate easily, while high-affinity antibodies generally bind to the antigen more rapidly and tend to remain bound for longer. A variety of methods for measuring binding affinity are known in the art, any of which can be used for the purposes of the present invention. Specific illustrative embodiments are described below.

[00160] Or rather, when used in this document to refer to binding affinity, it will refer to a stronger bond between a molecule and its bonding partner. Or rather, when used in this document it refers to a stronger connection, represented by a Petition 870260060475, dated 06 / 19 / 2026, p. 91 / 752 86 / 355 smaller numerical Kd value. For example, an antibody that has an affinity for an antigen of 0.3 nM or better, the antibody's affinity for the antigen is < 0.3 nM, for example, 0.29 nM, 0.28 nM, 0.27 nM, etc., or any value equal to or less than 0.3 nM. In one embodiment, the antibody affinity determined by a Kd will be between about 10⁻³ to about 10⁻¹² M, between about 10⁻⁶ to about 10⁻¹¹ M, between about 10⁻⁶ to about 10⁻¹⁰ M, between about 10⁻⁶ to about 10⁻⁹ M, between about 10⁻⁶ to about 10⁻⁸ M, or between about 10⁻⁶ to about 10⁻⁷ M.

[00161] By specifically binding, it generally means that an antibody binds to an epitope through its antigen-binding domain and that the binding implies some complementarity between the antigen-binding domain and the epitope. According to this definition, an antibody is said to specifically bind to an epitope when it binds to that epitope through its antigen-binding domain more readily than it would bind to a random, unrelated epitope. The term specificity is used in this document to qualify the relative affinity with which a given antibody binds to a given epitope. For example, antibody A may be considered to have a higher specificity for a given epitope than antibody B, or antibody A may be designed to bind to epitope C with a higher specificity than to the related epitope D.

[00162] In certain embodiments, an antibody or antigen-binding fragment of the invention binds specifically to a CD123 antigen, insofar as it has a higher specificity for binding to the CD123 antigen (of any kind) than to a non-CD123 antigen. In certain embodiments, an antibody or antigen-binding fragment of the invention binds specifically to a human CD123 antigen, insofar as it has a higher Petition 870260060475, dated 06 / 19 / 2026, page 92 / 752 87 / 355 binding specificity to human CD123 antigen than to a non-human CD123 antigen (e.g., mouse or rat CD123).

[00163] By preferential binding, it is understood that the antibody binds specifically to an epitope more readily than it would bind to a related, similar, homologous, or analogous epitope. Thus, an antibody that preferentially binds to a particular epitope would be more likely to bind to that epitope than to a related epitope, even if such an antibody might cross-react with the related epitope. For example, in certain embodiments, an antibody or antigen-binding fragment of the invention preferentially binds to a human CD123 antigen on a mouse CD123.

[00164] An antibody is said to competitively inhibit the binding of a reference antibody to a given epitope if it preferentially binds to that epitope to the extent that it blocks, to some degree, the binding of the reference antibody to the epitope. Competitive inhibition can be determined by any method known in the art, for example, competitive ELISA assays. An antibody can be said to competitively inhibit the binding of the reference antibody to a given epitope by at least 90%, at least 80%, at least 70%, at least 60%, or at least 50%.

[00165] The phrase "substantially similar" or "substantially the same," as used in this document, denotes a sufficiently high degree of similarity between two numerical values ​​(generally one associated with an antibody of the invention and the other associated with a reference / comparator antibody) such that a person skilled in the art would consider the difference between the two values ​​to be of little or no biological and / or statistical significance within the context of the biological characteristics measured by said values. Petition 870260060475, dated 06 / 19 / 2026, p. 93 / 752 88 / 355 (e.g., Kd values). The difference between the two quoted values ​​is less than about 50%, less than about 40%, less than about 30%, less than about 20%, or less than about 10% depending on the value for the reference / comparison antibody.

[00166] An isolated polypeptide, antibody, polynucleotide, vector, cell, or composition is a form not found in nature. Isolated polypeptides, antibodies, polynucleotides, vectors, cells, or compositions include those that have been purified to a degree where they are no longer in a form in which they are found in nature. In some embodiments, an isolated antibody, polynucleotide, vector, cell, or composition is substantially pure.

[00167] In this document, substantially pure refers to material that is at least 50% pure (i.e., free from contaminants), at least 90% pure, at least 95% pure, at least 98% pure, or at least 99% pure.

[00168] The term immunoconjugate, conjugate or ADC, as used in this document, refers to a compound or a derivative thereof that is linked to a cell-binding agent (i.e., an anti-CD123 / IL-3Ra antibody or a fragment thereof) and is defined by a generic formula: ALC, where C = cytotoxin, L = ligand and A = cell-binding agent (CBA), such as anti-CD123 / IL-3Ra antibody or antibody fragment. Immunoconjugates may also be defined by the generic formula in reverse order: CLA.

[00169] A ligand is any chemical unit capable of binding a compound, usually a drug, such as a cytotoxic agent described in this document (e.g., maytansinoid compounds or IGN (indolinobenzodiazepine)), to a cell-binding agent such as an anti-CD123 / IL-3Ra antibody or a fragment thereof in a form Petition 870260060475, dated 06 / 19 / 2026, p. 94 / 752 89 / 355 stable covalent. The ligands may be susceptible or substantially resistant to acid-induced cleavage, light-induced cleavage, peptidase-induced cleavage, esterase-induced cleavage, and disulfide bond cleavage, under conditions whereby the compound or antibody remains active. Suitable ligands are well known in the art and include, for example, disulfide groups, thioether groups, acid-labile groups, photolabile groups, peptidase-labile groups, and esterase-labile groups. Ligands also include charged ligands and hydrophilic forms thereof, as described herein and as known in the art.

[00170] The terms elevated CD123 / IL-3Ra, increased CD123 / IL-3Ra expression, and CD123 / IL-3Ra overexpression refer to a sample containing elevated levels of CD123 expression. CD123 may be elevated, increased, or overexpressed compared to a control value (e.g., expression level in a biological sample, tissue, or cell from an individual without cancer, a sample or cancer known to express no or low CD123 / IL-3Ra, a normal sample, or a cancer that does not have CD123 / IL-3Raα values). For example, a sample (e.g., a sample from a hematologic cancer such as leukemia and lymphoma) with increased expression may contain an increase of at least 2, 3, 4, 5, 10, 15, 20, 25, 30, or at least 50 times relative to control / normal values.

[00171] A reference sample can be used to correlate and compare the results obtained in the methods of the invention from a test sample. Reference samples can be cells (e.g., cell lines, cell precipitate) or tissue. The CD123 / IL-3Rα levels in the reference sample can be an absolute or relative amount, a quantity variation, a minimum and / or maximum amount, an amount Petition 870260060475, dated 06 / 19 / 2026, page 95 / 752 90 / 355 mean and / or a median amount of CD123 / IL-3Ra. A reference sample may also serve as a baseline of CD123 / IL-3Ra expression to which the test sample is compared. The reference sample may include a previous sample or baseline sample from the same patient, a normal reference with a known level of CD123 / IL-3Ra expression, or a reference from a relevant patient population with a known level of CD123 / IL-3Rα expression. CD123 / IL-3Rα levels may also be expressed as values ​​on a standard curve. A standard curve is a quantitative method of plotting assay data to determine the concentration of CD123 / IL-3Rα in a sample. In one embodiment, a reference sample is an antigen standard comprising purified CD123 / IL-3Rα. The diagnostic methods of the invention may involve a comparison between the expression levels of CD123 / IL-3Rα in a test sample and a reference value.In some modalities, the reference value is the CD123 / IL-3Rα expression level in a reference sample. A reference value can be a predetermined value and can also be determined from reference samples (e.g., control biological samples or reference samples) tested in parallel with the test samples. A reference value can be a single cutoff value, such as a median or mean, or a range of values, such as a confidence interval. Reference values ​​can be established for various subgroups of individuals.

[00172] The term primary antibody in this document refers to an antibody that binds specifically to the target protein antigen in a sample. A primary antibody is usually the first antibody used in an ELISA assay or an IHC procedure. In one embodiment, the primary antibody is the only antibody used in an IHC procedure. Petition 870260060475, dated 06 / 19 / 2026, p. 96 / 752 91 / 355

[00173] The term secondary antibody, in this document, refers to an antibody that binds specifically to a primary antibody, thus forming a bridge or link between the primary antibody and a subsequent reagent, if any. A secondary antibody is generally the second antibody used in an immunohistochemistry procedure.

[00174] A sample or biological sample of the present invention is of biological origin, in specific embodiments, such as from eukaryotic organisms. In some embodiments, the sample is a human sample, but animal samples may also be used. Non-limiting sources of a sample for use in the present invention include solid tissue, biopsy aspirates, ascitic and fluidic extracts, blood, plasma, serum, cerebrospinal fluid, lymphatic fluid, outer sections of the skin, respiratory, intestinal and genitourinary tracts, tears, saliva, milk, tumors, organs, cell cultures or cell culture constituents, for example. A cancerous sample is a sample that contains a cancerous cell.The method can be used to examine an aspect of CD123 / IL-3Ra expression or a sample state, including, but not limited to, comparison of different cell or tissue types, comparison of different developmental stages, and detection or determination of the presence and / or type of disease or abnormality.

[00175] As used in this document, the term capture reagent refers to a reagent capable of binding and capturing a target molecule in a sample under suitable conditions, so that the capture target molecule-reactant complex can be separated from the rest of the sample. In one embodiment, the capture reagent is immobilized. In one embodiment, the capture reagent in a sandwich immunoassay is an antibody or a mixture of different antibodies against a target antigen. Petition 870260060475, dated 06 / 19 / 2026, page 97 / 752 92 / 355

[00176] As used in this document, the term detectable antibody refers to an antibody that is capable of being detected directly by means of a label amplified by a detection medium, or indirectly, by means of, for example, another antibody that is labeled. For direct labeling, the antibody is normally conjugated to a moiety that is detectable by some means. In one embodiment, the detectable antibody is a biotinylated antibody.

[00177] As used in this document, the term detection medium refers to a portion or technique used to detect the presence of detectable antibody and includes detection agents that amplify the immobilized marker as a marker captured on a microtiter plate. In one embodiment, the detection media are a fluorimetric detection agent such as avidin or streptavidin.

[00178] Commonly, a combined ELISA employs the following steps: (1) the microtiter plate is coated with a capture antibody; (2) the sample is added, and any antigen present binds to the capture antibody; (3) the detection antibody is added and binds to the antigen; (4) the enzyme-linked secondary antibody is added and binds to the detection antibodies; and (5) substrate is added and is converted by the enzyme into a detectable form.

[00179] The word marker, when used in this document, refers to a detectable compound or composition that is conjugated directly or indirectly to an antibody in order to generate a labeled antibody. The marker may be detectable on its own (e.g., radioisotope markers or fluorescent markers) or, in the case of an enzymatic marker, it may catalyze the chemical change of a substrate compound or composition that is detectable.

[00180] By correlation or correlation is meant the comparison, in any form, of the performance and / or results of a first analysis with the performance and / or results of a second analysis. Petition 870260060475, dated 06 / 19 / 2026, page 98 / 752 93 / 355 For example, the results of an initial analysis can be used in conducting a second analysis, and / or someone can use the results of an initial analysis to determine whether a second analysis should be performed, and / or someone can compare the results of an initial analysis with the results of a second analysis. In one modality, increased CD123 / IL-3Ra expression correlates with a higher probability of efficacy of a CD123 / IL-3Ra-targeted therapy.

[00181] The terms cancer and cancerous refer to or describe the physiological condition in mammals in which a population of cells is characterized by unregulated cell growth. Tumor and neoplasm refer to one or more cells resulting from excessive cell growth or proliferation, benign (non-cancerous) or malignant (cancerous), including precancerous lesions.

[00182] Examples of cancer include lymphoma and leukemia. Examples of cancers or tumorous diseases that can be treated and / or prevented by the methods and reagents (e.g., the anti-CD123 antibody, its antigen-binding fragment, or its immunoconjugate) of the invention include AML, CML, ALL (e.g., B-ALL), CLL, myelodysplastic syndrome, basic plasmacytoid DC neoplasm leukemia (BPDCN), B-cell lymphomas including non-Hodgkin lymphomas (NHL), precursor B-cell lymphoblastic leukemia / lymphoma, and mature B-cell neoplasms.such as B-cell chronic lymphocytic leukemia (B-CLL) / small lymphocytic lymphoma (SLL), B-cell prolymphocytic leukemia, lymphoplasmacytic lymphoma, mantle cell lymphoma (MCL), follicular lymphoma (FL), including low-grade, intermediate-grade and high-grade FL, central cutaneous follicle lymphoma, marginal zone B-cell lymphoma (MALT type, nodal type and splenic type), hairy cell leukemia (HCL), diffuse large B-cell lymphoma, Burkitt lymphoma, plasmacytoma, plasma cell myeloma, disorder, Petition 870260060475, dated 06 / 19 / 2026, page 99 / 752 94 / 355 post-transplant lymphoproliferative disorder, Waldenstrom's macroglobulinemia, anaplastic large cell lymphoma (ALCL), and Hodgkin's leukemia (HL).

[00183] Cancers also include cancers that contain cells with high levels of CD123 / IL-3Ra expression. These CD123 / IL-3Ra high-expressing cancers include, but are not limited to, AML, CML, ALL (e.g., B-ALL), and CLL.

[00184] The terms cancer cells, tumor cells, and grammatical equivalents refer to the total population of cells derived from a tumor or precancerous lesion, including both non-tumorigenic cells, which comprise the majority of the tumor cell population, and tumorigenic stem cells (cancer stem cells). In this document, the term tumor cell will be modified by the term non-tumorigenic when referring only to tumor cells that lack the ability to renew and differentiate, in order to distinguish these tumor cells from cancer stem cells.

[00185] The term subject refers to any animal (e.g., a mammal), including but not limited to humans, non-human primates, rodents, and the like, that is the recipient of a specific treatment. Typically, the terms subject and patient are used interchangeably with respect to a human subject.

[00186] Administration in combination with one or more additional therapeutic agents includes simultaneous (concomitant) and consecutive administration in any order.

[00187] The term pharmaceutical formulation refers to a preparation whose form allows the biological activity of the active ingredient to be effective, and which does not contain additional components that are unacceptably toxic to an individual to whom the formulation will be administered. Such a formulation may be sterile. Petition 870260060475, dated 06 / 19 / 2026, page 100 / 752 95 / 355

[00188] An effective amount of an antibody or immunoconjugate as disclosed in this document is an amount sufficient to achieve a specifically stated objective. An effective amount can be determined empirically and routinely in relation to the stated objectives.

[00189] The term therapeutically effective amount refers to an amount of an antibody or other drug effective in treating a disease or disorder in a subject or mammal.In the case of cancer, the therapeutically effective amount of the drug may reduce the number of cancer cells; reduce tumor size; inhibit (i.e., delay to some extent and in a given modality, stop) cancer cell infiltration into peripheral organs; inhibit (i.e., delay to some extent and in a given modality, stop) tumor metastasis; inhibit, to some extent, tumor growth; alleviate, to some extent, one or more symptoms associated with cancer; and / or result in a favorable response, such as increased progression-free survival (PFS), disease-free survival (DFS) or overall survival (OS), complete response (CR), partial response (PR), or, in some cases, stable disease (SD), reduction of progressive disease (PD), reduced time to progression (TTP), or any combination thereof. See the definition of treat in this document.Since the drug can inhibit the growth and / or kill existing cancer cells, it can be cytostatic and / or cytotoxic.

[00190] A prophylactically effective amount refers to an amount that is effective, in doses and for the time periods required, to achieve the desired prophylactic result. Typically, but not necessarily, once a prophylactic dose is used in subjects before or in an early stage of the disease, the prophylactically effective amount will be less than the amount Petition 870260060475, dated 06 / 19 / 2026, p. 101 / 752 96 / 355 therapeutically effective.

[00191] The term respond favorably generally refers to causing a beneficial state in a subject. In relation to cancer treatment, the term refers to providing a therapeutic effect on the subject. Positive therapeutic effects in cancer can be measured in a number of ways (See, WA Weber, J. Nucl. Med. 50:1S10S (2009)). For example, tumor growth inhibition, molecular marker expression, serum marker expression, and molecular imaging techniques can be used to assess the therapeutic efficacy of a cancer therapy. Regarding tumor growth inhibition, according to NCI guidelines, a T / C < 42% is the minimum level of antitumor activity. A T / C < 10% is considered a high level of antitumor activity, with T / C (%) = median treated tumor volume / median control tumor volume x 100.A favorable response can be assessed, for example, by an increase in progression-free survival (PFS), disease-free survival (DFS) or overall survival (OS), complete response (CR), partial response (PR), or, in some cases, stable disease (SD), a decrease in progressive disease (PD), a reduction in time to progression (TTP), or any combination of the above.

[00192] PFS, DFS, and OS can be measured by the standards established by the US National Cancer Institute and the US Food and Drug Administration for the approval of new drugs. See Johnson et al., (2003) J. Clin. Oncol. 21(7): 1404-1411.

[00193] Progression-free survival (PFS) refers to the time period from admission until disease progression or death. PFS is generally measured using the Kaplan-Meier method and the Evaluation of Response in Solid Tumors (RECIST) guidelines 1.1. Generally, progression-free survival refers to the situation in which a patient remains alive without the cancer worsening. Petition 870260060475, dated 06 / 19 / 2026, page 102 / 752 97 / 355

[00194] A complete response or complete remission or CR indicates the disappearance of all signs of tumor or cancer in response to treatment. This does not always mean that the cancer has been cured.

[00195] A partial response or PR refers to a decrease in the size or volume of one or more tumors or lesions, or in the extent of cancer in the body, in response to treatment.

[00196] Stable disease refers to disease without progression or recurrence. In stable disease, there is neither sufficient reduction in tumor size to qualify as a partial response nor sufficient increase in tumor size to qualify as progressive disease.

[00197] Progressive disease refers to the appearance of more new lesions or tumors and / or the unequivocal progression of existing non-target lesions. Progressive disease may also refer to the growth of a tumor by more than 20% since the start of treatment, due to an increase in mass or spread of the tumor.

[00198] Disease-free survival (DFS) refers to the length of time during and after treatment that the patient remains free from disease.

[00199] Overall Survival (OS) refers to the period of time from the patient's admission until death or the date recorded on the last date they were alive. OS includes an extension of life expectancy compared to unexposed or untreated individuals or patients. Overall survival refers to the situation in which a patient remains alive for a given period of time, such as one year, five years, etc., for example, from diagnosis or treatment.

[00200] A chemotherapeutic agent is a chemical compound useful in the treatment of cancer, regardless of its mechanism of action. Terms such as treat or treatment or to treat or relieve or to Petition 870260060475, dated 06 / 19 / 2026, page 103 / 752 98 / 355 relief refers to therapeutic measures that cure, slow down, reduce symptoms, and / or halt the progression of a diagnosed pathological condition or disorder. Thus, those who require treatment include those already diagnosed with the disorder, and may also include those with minimal residual disease, resistant disease, or relapsing disease. In certain embodiments, an individual is treated for cancer according to the methods of the present invention if the patient exhibits one or more of the following: a reduction in the number of or complete absence of cancer cells; a reduction in tumor size; inhibition or absence of cancer cell infiltration into peripheral organs, including, for example, the spread of cancer into soft tissues and bone; inhibition of or absence of tumor metastases; inhibition or absence of tumor growth; relief of one or more symptoms associated with the specific cancer; reduction in morbidity and mortality;Improvement in quality of life; reduction in tumorigenicity, tumorigenic frequency, or tumorigenic capacity of a tumor; reduction in the number or frequency of cancer stem cells in a tumor; differentiation of tumorigenic cells to a non-tumorigenic state; increase in progression-free survival (PFS), disease-free survival (DFS), or overall survival (OS), complete response (CR), partial response (PR), stable disease (SD), a decrease in progressive disease (PD), a reduction in time to progression (TTP), or any combination thereof.

[00201] Prophylactic or preventive measures refer to measures that prevent and / or delay the development of a targeted pathological condition or disorder. Thus, those who need prophylactic or preventive measures include those prone to having the disorder and those in whom the disorder should be prevented.

[00202] Prophylactic or preventive measures refer to measures Petition 870260060475, dated 06 / 19 / 2026, page 104 / 752 99 / 355 therapies that prevent and / or delay the development of a targeted pathological condition or disorder. Thus, those who need prophylactic or preventive measures include those prone to having the disorder and those in whom the disorder should be prevented.

[00203] In this document, the term health professional refers to individuals or institutions that interact with and administer directly to living subjects, for example, human patients. Non-limiting examples of health professionals include physicians, nurses, technicians, therapists, pharmacists, counselors, alternative medicine practitioners, medical facilities, medical offices, hospitals, emergency rooms, clinics, urgent care centers, alternative medicine clinics / comforts, and any other entity providing general and / or specialized treatment, assessment, maintenance, therapy, medication, and / or advice related to all, or any part of, a patient's health status, including but not limited to general, specialized, medical, surgical, and / or any other type of treatment, assessment, maintenance, therapy, medication, and / or advice.

[00204] In some respects, a healthcare professional may administer or entrust another healthcare professional with administering a therapy to treat cancer. Administration of a therapy, as used in this document, includes prescribing a therapy to an individual, as well as providing, applying, or giving the therapy to the individual. A healthcare professional may implement or entrust another healthcare professional or patient with performing the following actions: obtaining a sample, processing a sample, submitting a sample, receiving a sample, transferring a sample, analyzing or measuring a sample, quantifying a sample, providing the results obtained after analyzing / measuring / quantifying a sample, receiving the results obtained Petition 870260060475, dated 06 / 19 / 2026, page 105 / 752 100 / 355 after analyzing / measuring / quantifying a sample, compare / mark the results obtained after analyzing / measuring / quantifying one or more samples, provide the comparison / marking of one or more samples, obtain the comparison / marking of one or more samples, administer a therapy or therapeutic agent (e.g., a CD123 / IL-3Ra binding agent), initiate administration of a therapy, interrupt administration of a therapy, continue administration of a therapy, temporarily interrupt administration of a therapy, increase the amount of a therapeutic agent administered, decrease the amount of a therapeutic agent administered, continue administration of an amount of a therapeutic agent, increase the frequency of administration of a therapeutic agent, decrease the frequency of administration of a therapeutic agent, maintain the same dosing frequency of a therapeutic agent,To replace a therapy or therapeutic agent with at least one other therapeutic agent or therapy, or to combine a therapy or therapeutic agent with at least one other additional therapy or therapeutic agent. These actions can be performed by a healthcare professional automatically using a computer-implemented method (e.g., through a web-based service or stand-alone computer system).

[00205] Polynucleotide or nucleic acid, as used alternatively in this document, refers to polymers of nucleotides of any length and includes DNA and RNA. Nucleotides may be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases, and / or their analogs or any substrate that can be incorporated into a polymer by DNA or RNA polymerase. A polynucleotide may comprise modified nucleotides, such as methylated nucleotides and their analogs. If present, modification of the nucleotide structure may be Petition 870260060475, dated 06 / 19 / 2026, p. 106 / 752 101 / 355 transmitted before or after polymer assembly. The nucleotide sequence can be interrupted by non-nucleotide components. A polynucleotide can be modified even after polymerization, such as by conjugation with a labeling component. Other types of modifications include, for example, capping, the substitution of one or more of the naturally occurring nucleotides with an analog, internucleotide modifications, such as, for example, those with uncharged bonds (e.g., methyl phosphonates, phosphotriasters, phosphoamidates, etc.) and with charged bonds (e.g., phosphorothioates, phosphorodithioates, etc.), those containing pendant portions, such as, for example, proteins (e.g., nucleases, toxins, antibodies, signal peptides, ply-L-lysine, etc.), those with intercalators (e.g., acridine, psoralen, etc.).Polynucleotides (PNUs) contain chelating agents (e.g., metals, radioactive metals, boron, oxidative metals, etc.), alkylating agents, modified linkages (e.g., alpha anomeric nucleic acids, etc.), as well as unmodified forms of the polynucleotide(s). Furthermore, any of the hydroxyl groups generally present in sugars can be substituted, for example, by phosphonate groups, phosphate groups, protected by standard protecting groups, or activated to prepare additional linkages for additional nucleotides, or it can be conjugated with solid or semi-solid supports. The OH groups with 5' and 3' terminations can be phosphorylated or substituted by amines or portions of organic coating groups of 1 to 20 carbon atoms. Other hydroxyl groups can also be derived from standard protecting groups.Polynucleotides may also contain analogous forms of ribose or deoxyribose sugars that are generally known in the art, including, for example, 2'-O-methyl-, 2'-O-allyl, 2'-fluoro or 2'-azido-ribose, analogous carbocyclic sugars. Petition 870260060475, dated 06 / 19 / 2026, page 107 / 752 102 / 355 alpha-anomeric, epimeric sugars such as arabinose, xylose, or lyxose, pyranose sugars, furanose sugars, heptuloses, acyclic analogs, and analogs of basic nucleosides such as methylriboside. One or more phosphodiester linkages may be substituted by alternative linkage groups. These alternative linkage groups include, but are not limited to, embodiments in which the phosphate is substituted by P(O)S (thioate), P(S)S (dithioate), (O)NR2 (amidate), P(O)R, P(O)OR*, CO, or CH2 (formacetal), where each R or R is independently H or alkyl substituted or unsubstituted (1-20 C) optionally containing an ether (-O-), aryl, alkenyl, cycloalkyl, cycloalkenyl, or araldyl linkage. Not all linkages in a polynucleotide need to be identical. The preceding description applies to all polynucleotides mentioned here, including RNA and DNA.

[00206] The term vector refers to a construct that is capable of delivering and expressing one or more genes or sequences of interest in a host cell. Examples of vectors include, but are not limited to, viral vectors, pure DNA or RNA expression vectors, plasmid, cosmid or phage vectors, DNA or RNA expression vectors associated with cationic condensation agents, DNA or RNA expression vectors encapsulated in liposomes, and certain eukaryotic cells, such as producer cells.

[00207] The terms polypeptide, peptide, and protein are used interchangeably in this document to refer to polymers of amino acids of any length. Polymers may be linear or branched, may comprise modified amino acids, and may be interrupted by non-amino acids. The terms also encompass an amino acid polymer that has been modified naturally or by intervention; for example, by disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation or modification, such as conjugation with a Petition 870260060475, dated 06 / 19 / 2026, page 108 / 752 103 / 355 labeling component. Also included in the definition are, for example, polypeptides containing one or more analogs of an amino acid (including, for example, non-natural amino acids, etc.), as well as other modifications known in the art. It is understood that, since the polypeptides of this invention are based on antibodies, in certain embodiments, the polypeptides may occur as single chains or associated chains. In some embodiments, a polypeptide, peptide, or protein is non-naturally occurring. In some embodiments, a polypeptide, peptide, or protein is purified from other naturally occurring components. In some embodiments, the polypeptide, peptide, or protein is produced recombinantly.

[00208] The terms identical or percent identity in the context of two or more nucleic acids or polypeptides refer to two or more sequences or subsequences that are identical or have a specified percent of nucleotides or amino acid residues that are the same when compared and aligned (introducing gaps, if necessary) to maximum correspondence, not considering any conservative amino acid substitutions as part of the sequence identity. Percent identity can be measured using sequence comparison software or algorithms or by visual inspection. Several algorithms and software are known in the art that can be used to obtain alignments of amino acid or nucleotide sequences. A non-limiting example of a sequence alignment algorithm is the algorithm described in Karlin et al., Proc. Natl. Acad. Sci. 87:2264-2268, 1990, as modified in Karlin et al., Proc. Natl. Acad. Sci.90:5873-5877, 1993, and incorporated into the NBLAST and XBLAST programs (Altschul et al., Nucleic Acids Res. 25:3389-3402, 1991). In certain embodiments,. Gapped BLAST can be used as described in Altschul et al. Petition 870260060475, dated 06 / 19 / 2026, page 109 / 752 104 / 355 Nucleic Acids Res. 25:3389-3402, 1997; BLAST-2, WU-BLAST-2 (Altschul et al., Methods in Enzymology 266:460-480, 1996), ALIGN, ALIGN-2 (Genentech, South San Francisco, California) or Megalign (DNASTAR) are additional publicly available software programs that can be used to align sequences. In certain embodiments, the percent identity between two nucleotide sequences is determined using the GAP program in the Accelrys GCG software package (e.g., using an NWSgapdna.CMP array and a gap weight of 40, 50, 60, 70, or 90 and a length weight of 1, 2, 3, 4, 5, or 6). In certain alternative modalities, the GAP program in the GCG software package, which incorporates the Needleman and Wunsch algorithm (J. Mol. Biol.(48):444453, 1970) can be used to determine the percent identity between two amino acid sequences (e.g., using either the Blossum 62 matrix or a PAM250 matrix and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5). Alternatively, in certain embodiments, the percent identity between nucleotide or amino acid sequences is determined using the Myers and Miller algorithm (CABIOS, 4: 1117, 1989). For example, percent identity can be determined using the ALIGN program (version 2.0) and using a PAM120 with a residue table, a gap length penalty of 12, and a gap penalty of 4. The appropriate parameters for maximum alignment by the specific alignment software can be determined by those skilled in the art. In certain applications, standard alignment software parameters are used.In certain embodiments, the percent identity X of a first amino acid sequence to a second amino acid sequence is calculated as 100 x (Y / Z), where Y is the number of amino acid residues scored as matches. Petition 870260060475, dated 06 / 19 / 2026, p. 110 / 752 105 / 355 identical in the alignment of the first and second sequences (as aligned by visual inspection or a specific sequence alignment program) and Z is the total number of residues in the second sequence. If the length of a first sequence is greater than that of the second sequence, the percent identity of the first sequence with respect to the second sequence will be greater than the percent identity of the second sequence with respect to the first sequence.

[00209] As a non-limiting example, whether any given polynucleotide has a certain percent sequence identity (e.g., is at least 80% identical, at least 85% identical, at least 90% identical, and in some embodiments at least 95%, 96%, 97%, 98%, or 99% identical) with respect to a reference sequence can, in certain embodiments, be determined using the Bestfit program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, 575 Science Drive, Madison, WI 53711). Bestfit uses the local homology algorithm of Smith and Waterman, Advances in Applied Mathematics 2: 482-489, 1981, to find the best homology segment between two sequences.When using Bestfit or any other sequence alignment program to determine whether a specific sequence is, for example, 95% identical to a reference sequence, according to the present invention, the parameters are defined, of course, such that the percentage of identity is calculated over the entire length of the reference nucleotide sequence and that gaps in homology of up to 5% of the total number of nucleotides in the reference sequence are allowed.

[00210] In some embodiments, two nucleic acids or polypeptides of the invention are substantially identical, meaning that they have at least 70%, at least 75%, at least 80%, at least 85%, at least 90% and, in some embodiments, at least Petition 870260060475, dated 06 / 19 / 2026, p. 111 / 752 106 / 355 95%, 96%, 97%, 98%, 99% nucleotide or amino acid residue identity when compared and aligned for maximum match, as measured using a sequence comparison algorithm or by visual inspection. In certain embodiments, there is identity with respect to a sequence region of at least about 10, about 20, about 40-60 residues in length or any integer value between them, or with respect to a region longer than 60-80 residues, at least about 90-100 residues, or the sequences are substantially identical with respect to the total length of the sequences being compared, such as the coding region of a nucleotide sequence, for example.

[00211] A conservative amino acid substitution is one in which the amino acid residue is replaced by an amino acid residue having a similar side chain. Families of amino acid residues with similar side chains have been defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine), and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). For example, replacing phenylalanine with tyrosine is a conservative substitution.In certain embodiments, the conservative substitutions in the polypeptide and antibody sequences of the invention do not abolish the binding of the polypeptide or antibody containing an amino acid sequence to the antigens, i.e., CD123 / IL-3Ra to which the... Petition 870260060475, dated 06 / 19 / 2026, p. 112 / 752 107 / 355 polypeptide or antibody binds. Methods for identifying nucleotides and conservative amino acid substitutions that do not eliminate antigen binding are well known in the art (see, for example, Brummell et al., Biochem. 32:1180-1187, 1993; Kobayashi et al., Protein Eng. 12(10):879-884, 1999; and Burks et al., Proc. Natl. Acad. Sci. USA 94:412-417, 1997).

[00212] In this document, P-glycoprotein 1, also known as permeability glycoprotein, P-gp or Pgp, multidrug resistance protein 1 (MDR1), ATP-binding cassette subfamily B member 1 (ABCB1), or cluster of differentiation 243 (CD243), is an ABC transporter of the MDR / TAP subfamily that transports a wide variety of substrates across extra- and intracellular membranes. It is an ATP-dependent effluent pump with broad substrate specificity. P-gp is widely distributed and expressed in the intestinal epithelium where it lifts xenobiotics (such as toxins or drugs) back into the intestinal lumen, in liver cells where it pumps them into the bile ducts, in the proximal tubule cells of the kidney where it pumps them into the urinary ducts, and in the capillary endothelial cells that make up the blood-brain barrier and the blood-testis barrier, where it returns them to the capillaries.

[00213] Some cancer cells also express large amounts of P-gp, which makes these cancers resistant to several drugs.

[00214] Alkyl as used in this document refers to a linear or branched-chain saturated monovalent hydrocarbon radical of one to twenty carbon atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-methyl-1-propyl, -CH2CH(CH3)2), 2-butyl, 2-methyl-2-propyl, 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 3-methyl-1-butyl, 2-methyl-1-butyl, 1-hexyl), 2-hexyl, 3-hexyl, 2-methyl-2-pentyl, 3-methyl-2 Petition 870260060475, dated 06 / 19 / 2026, page 113 / 752 108 / 355 pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl-3-pentyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, 1-heptyl, 1-octyl, and the like. Preferably, the alkyl group has one to ten carbon atoms. More preferably, the alkyl group has one to four carbon atoms.

[00215] The number of carbon atoms in a group can be specified in this document by the prefix Cx-xx, where x and xx are integers. For example, C1-4alkyl is an alkyl group with 1 to 4 carbon atoms.

[00216] The term compound or cytotoxic compound are used interchangeably. They are intended to include compounds for which a structure or formula or any respective derivative has been described in the present invention, or a structure or formula or any respective derivative has been incorporated by reference. The term also includes stereoisomers, geometric isomers, tautomers, solvates, metabolites, salts (e.g., pharmaceutically acceptable salts), of a compound of all the formulas described in the present invention. The term also includes any solvates, hydrates and polymorphs of any of the foregoing.The specific mention of stereoisomers, geometric isomers, tautomers, solvates, metabolites, salts, conjugates, salts of conjugates, solvates, hydrates, or polymorphs in certain aspects of the invention described in this patent application should not be interpreted as an intended omission of these forms in other aspects of the invention where the term compound is used without mention of these other forms.

[00217] The term chiral refers to molecules that have the property of non-superposition of the mirror-image partner, while the term achiral refers to molecules that are superimposed on their mirror-image partner.

[00218] The term stereoisomer refers to compounds that have identical chemical constitution and connectivity, but different Petition 870260060475, dated 06 / 19 / 2026, p. 114 / 752 109 / 355 orientations of their atoms in space that cannot be interconverted by rotation around single bonds.

[00219] Diastereomer refers to a stereoisomer with two or more chiral centers and whose molecules are not mirror images of each other. Diastereomers have different physical properties, for example, melting points, boiling points, spectral properties, and reactivities. Mixtures of diastereomers can be separated under high-resolution analytical procedures such as crystallization, electrophoresis, and chromatography.

[00220] Enantiomers refer to two stereoisomers of a compound that are non-superimposable mirror images of each other.

[00221] Definitions and stereochemical conventions used in this document generally follow S.P. Parker, Ed., McGraw-Hill, Dictionary of Chemical Terms (1984) McGraw-Hill Book Company, New York; and Eliel, E. and Wilen, S., Stereochemistry of Organic Compounds, John Wiley & Sons, Inc., New York, 1994. The compounds of the invention may contain asymmetric or chiral centers and therefore exist in different stereoisomeric forms. It is intended that all stereoisomeric forms of the compounds of the invention, including but not limited to diastereomers, enantiomers and atropisomers, as well as mixtures thereof, such as racemic mixtures, form part of the present invention. Many organic compounds exist in optically active forms, that is, they have the ability to rotate the plane of polarized light in the plane. In the description of an optically active compound, the prefixes D and L, or R and S, are used to denote the absolute configuration of the molecule about its chiral center(s).The prefixes del or (+) and (-) are used to designate the sign of the rotation of plane-polarized light by the compound, with (-) or 1 meaning that the compound is levorotatory. A compound prefixed with (+) or d is dextrorotatory. For a given chemical structure, these... Petition 870260060475, dated 06 / 19 / 2026, p. 115 / 752 110 / 355 stereoisomers are identical except that they are mirror images of each other. A specific stereoisomer may also be referred to as an enantiomer, and a mixture of such isomers is often called an enantiomeric mixture. A 50:50 mixture of enantiomers is referred to as a racemic mixture or a racemate, which can occur where there has been no stereoselection or stereospecificity in a chemical reaction or process. The terms racemic mixture and racemate refer to an equimolar mixture of two enantiomeric species, devoid of optical activity.

[00222] The term tautomer or tautomeric form refers to structural isomers of energies that are interconvertible across a low energy barrier. For example, proton tautomers (also known as prototropic tautomers) include interconversions through the migration of a proton, such as keto-enol and imine-enamine isomerizations. Valence tautomers include interconversions by rearranging some of the bonding electrons.

[00223] The term imine reactive reagent refers to a reagent that is capable of reacting with an imine group. Examples of imine reactive reagents include, but are not limited to, sulfites (H2SO3, H2SO2 or a salt of HSO3-, SO32- or HSO2-formed with a cation), metabisulfite (H2S2O5 or a salt of S2O52-formed with a cation), mono-, di-, tri- and tetra-thiophosphates (PO3SH3, PO2S2H3, POS3H3, PS4H3 or a salt of PO3S3-, PO2S23-, POS33- or PS43-formed with a cation), thiophosphate esters ((RiO)2PS(ORi), RiSH, RiSOH, RiSO2H, RiSO3H), various amines (hydroxylamine (e.g., NH2OH), hydrazine (e.g., NH2NH2), NH2O-R Ri'NH-Ri, NH2-Ri), NH2-CO-NH2, NH2-C(=S)-NH2, thiosulfate (H2S2O3 or an S2O32-formed salt with cation), dithionite (H2S2O4 or an S2O42-formed salt with cation), phosphorodithioate (P(=S)(ORk)(SH)(OH) or its salt formed with cation), acid Petition 870260060475, dated 06 / 19 / 2026, p. 116 / 752 111 / 355 hydroxamic (RkC(=O)NHOH or a salt formed with a cation), hydrazide (RkCONHNH2), formaldehyde sulfoxylate (HOCH2SO2H or a salt of HOCH2SO2-formed with a cation, such as HOCH2SO2-Na+), glycated nucleotide (such as GDP-mannose), fludarabine or a mixture thereof, wherein Ri and Ri' are independently a linear or branched alkyl with 1 to 10 carbon atoms and are substituted by at least one substituent selected from -N(Rj)2, -CO2H, -SO3H, and PO3H; Ri and Ri' may optionally be further substituted by a substituent for an alkyl described in this document; Rj is a linear or branched alkyl with 1 to 6 carbon atoms; and Rk is a linear, branched or cyclic alkyl, alkenyl or alkynyl group with 1 to 10 carbon atoms, aryl, heterocyclyl or heteroaryl group (preferably, Rk is a linear or branched alkyl group with 1 to 4 carbon atoms; more preferably, Rk is methyl, ethyl or propyl). Preferably, the cation is a monovalent cation, such as Na+ or K+.Preferably, the reactive imine reagent is selected from sulfites, hydroxylamine, urea, and hydrazine. More preferably, the reactive imine reagent is NaHSO3 or KHSO3.

[00224] The phrase "pharmaceutically acceptable salt" as used in this document refers to pharmaceutically acceptable organic or inorganic salts of a compound of the invention. Illustrative salts include, but are not limited to, salts of sulfate, citrate, acetate, oxalate, chloride, bromide, iodide, nitrate, bisulfate, phosphate, acid phosphate, isonicotinate, lactate, salicylate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucuronate, saccharate, formate, benzoate, glutamate, methanesulfonate mesylate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, pamoate (i.e., 1,1'-methylene-bis(2-hydroxy-3-naphthoate)), alkali metal (e.g., sodium and potassium), alkaline earth metal (e.g., magnesium), and salts. Petition 870260060475, dated 06 / 19 / 2026, page 117 / 752 112 / 355 ammonium. A pharmaceutically acceptable salt may involve the inclusion of another molecule such as an acetate ion, a succinate ion, or another counterion. The counterion can be any organic or inorganic moiety that stabilizes the charge on the parent compound. Furthermore, a pharmaceutically acceptable salt may have more than one charged atom in its structure. Instances where multiple charged atoms are part of the pharmaceutically acceptable salt may have multiple counterions. Therefore, a pharmaceutically acceptable salt may have one or more charged atoms and / or one or more counterions.

[00225] If the compound of the invention is a base, the desired pharmaceutically acceptable salt can be prepared by any suitable method available in the art, for example, treatment of the free base with an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, methanesulfonic acid, phosphoric acid and the like, or with an organic acid, such as acetic acid, maleic acid, succinic acid, mandelic acid, fumaric acid, malonic acid, pyruvic acid, oxalic acid, glycolic acid, salicylic acid, a pyranosidyl acid, such as glucuronic acid or galacturonic acid, an alpha-hydroxy acid, such as citric acid or tartaric acid, an amino acid, such as aspartic acid or glutamic acid, an aromatic acid, such as benzoic acid or cinnamic acid, a sulfonic acid, such as p-toluenesulfonic acid or ethanesulfonic acid or similar.

[00226] If the compound of the invention is an acid, the desired pharmaceutically acceptable salt can be prepared by any suitable method, for example, by treating the free acid with an inorganic or organic base, such as an amine (primary, secondary or tertiary), an alkali metal hydroxide or alkaline earth metal hydroxide, or the like. Illustrative examples of suitable salts include, but are not limited to, organically derived salts. Petition 870260060475, dated 06 / 19 / 2026, page 118 / 752 113 / 355 of amino acids, such as glycine and arginine, ammonia, primary, secondary, and tertiary amines, and cyclic amines, such as piperidine, morpholine, and piperazine, and inorganic salts derived from sodium, calcium, potassium, magnesium, manganese, iron, copper, zinc, aluminum, and lithium.

[00227] In this document, the term solvate means a compound that additionally includes a stoichiometric or non-stoichiometric amount of solvent such as water, isopropanol, acetone, ethanol, methanol, DMSO, ethyl acetate, acetic acid, and dichloromethane, ethanolamine, 2-propanol, or the like, linked by non-covalent intermolecular forces. Solvates or hydrates of compounds are readily prepared by adding at least one molar equivalent of a hydroxyl solvent such as methanol, ethanol, 1-propanol, 2-propanol, or water to the compound to result in solvation or hydration of the imine moiety.

[00228] A metabolite or catabolite is a product produced through the metabolism or catabolism in the body of a specified compound, its derivative, or its conjugate, or its salt. The metabolites of a compound, a derivative thereof, or a conjugate thereof, can be identified using routine techniques known in the art and their activities determined using tests such as those described in this document. These products may result, for example, from the oxidation, hydroxylation, reduction, hydrolysis, amidation, deamidation, esterification, deesterification, enzymatic cleavage, and the like, of the administered compound. Therefore, the invention includes metabolites of the compounds, a derivative thereof, or a conjugate thereof, of the invention, including the compounds, a derivative thereof, or a conjugate thereof, produced by a process comprising contacting a compound, a derivative thereof, or a conjugate thereof, of the present invention with a mammal for a sufficient period of time. Petition 870260060475, dated 06 / 19 / 2026, page 119 / 752 114 / 355 to obtain a metabolic product of the same.

[00229] The phrase pharmaceutically acceptable indicates that the substance or composition must be chemically and / or toxicologically compatible with the other ingredients comprising a formulation and / or the mammal being treated with it.

[00230] The term protecting group or protective moiety refers to a substituent that is commonly used to block or protect a particular functionality while reacting with other functional groups in the compound, a derivative thereof, or a conjugate thereof. For example, an amine protecting group or aminoprotective moiety is a substituent attached to an amino group that blocks or protects the amino functionality of the compound. These groups are well known in the art (see, for example, P. Wuts and T. Greene, 2007, Protective Groups in Organic Synthesis, Chapter 7, J. Wiley & Sons, NJ) and exemplified by carbamates, such as methyl ethyl carbamate, FMOC, substituted ethyl carbamates, 1,6-β-eliminated cleaved carbamates (also called autoimmulatives), ureas, amides, peptides, and alkyl and aryl derivatives. Suitable amino protecting groups include acetyl, trifluoroacetyl, t-butoxycarbonyl (BOC), benzyloxycarbonyl (CBZ), and 9-fluorenylmethyleneoxycarbonyl (Fmoc).For a general description of protective groups and their use, see PGM Wuts & TW Greene, Protective Groups in Organic Synthesis, John Wiley & Sons, New York, 2007.

[00231] The term amino acid refers to naturally occurring amino acids or non-naturally occurring amino acids. In one embodiment, the amino acid is represented by NH2-C (Raa'Raa)C(=O)OH, wherein Raa and Raa' are each independently H, a linear, branched or cyclic alkyl, alkenyl or alkynyl optionally substituted with 1 to 10 carbon atoms, aryl, heteroaryl or heterocyclyl, or Raa and the terminal nitrogen atom N may form Petition 870260060475, dated 06 / 19 / 2026, p. 120 / 752 115 / 355 together form a heterocyclic ring (for example, as in proline). The term amino acid residue refers to the residue corresponding to the amino acid when a hydrogen atom is removed from the amine and / or carboxy end of the amino acid, such as -NH-C(Raa'Raa)-C(=O)O-.

[00232] The term cation refers to an ion with a positive charge. The cation can be monovalent (e.g., Na+, K+, NH4+, etc.), divalent (e.g., Ca2+, Mg2+, etc.) or multivalent (e.g., Al3+, etc.). Preferably, the cation is monovalent.

[00233] The term reactive ester group refers to an ester group that can readily react with an amine group to form an amide linkage. Examples of reactive ester groups include, but are not limited to, N-hydroxysuccinimide esters, N-hydroxyphthalimide esters, N-hydroxysulfosuccinimide esters, paranitrophenyl esters, dinitrophenyl esters, pentafluorophenyl esters and their derivatives, wherein said derivatives facilitate amide linkage formation. In certain embodiments, the reactive ester group is an N-hydroxysuccinimide ester or an N-hydroxysulfosuccinimide ester.

[00234] The term reactive amine group refers to a group that can react with an amine group to form a covalent bond. Examples of reactive amine groups include, but are not limited to, reactive ester groups, acyl halides, sulfonyl halides, imidoesters, or reactive thioester groups. In certain embodiments, the reactive amine group is a reactive ester group. In one embodiment, the reactive amine group is an N-hydroxysuccinimide ester or an N-hydroxy sulfosuccinimide ester.

[00235] The term thiol-reactive group refers to a group that can react with a thiol group (-SH) to form a covalent bond. Examples of thiol-reactive groups include, but are not limited to, maleimide, haloacetyl, alloacetamide, vinyl sulfone, vinyl sulfonamide, or vinyl pyridine. In one embodiment, the thiol-reactive group is Petition 870260060475, dated 06 / 19 / 2026, p. 121 / 752 116 / 355 maleimide.

[00236] As used in the present invention and claims, the singular forms a, uma and a / o include plural forms, unless the context clearly dictates otherwise.

[00237] It is understood that, whenever modalities are described in this document using the language comprising, analogous modalities described in terms of consisting of and / or consisting essentially of are also provided.

[00238] The term and / or, as used in a sentence such as A and / or B in this document, is intended to include both A and B, A or B, A and B. Similarly, the term and / or, as used in a sentence such as A, B and / or C, is intended to cover each of the following options: A, B and C; A, B or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone). Nomenclature of antibodies, compounds, and immunoconjugates.

[00239] In this document, the nomenclature used for anti-CD123 antibodies, cytotoxic compounds and their immunoconjugates generally adopts the following meanings.

[00240] CD123-3, -6 and -14 (or CD123 Mu-3, -6 and -14; or muCD1233, -6 and 14) are three murine anti-CD123 monoclonal antibodies. The CDR1-3 sequences of the heavy and light chains (VH-CDR1-3 and VLCDR1-3) are provided in Tables 1 and 2, with associated SEQ ID NOs: 1-25. The sequences of the heavy chain variable region (HCVR) are provided in Table 3A with associated SEQ ID NOs: 26, 28 and 30. Their sequences of the light chain variable region (LCVR) are provided in Table 4A with associated SEQ ID NOs: 27, 29 and 31. The full-length heavy chain (HC) sequences of the murine antibodies are provided in Table 5 (SEQ ID NOs: 42, 44, and 46), and the full-length light chain (LC) sequences of the murine antibodies are provided in Table 6 (SEQ ID NOs: 43, 45, and 46). Petition 870260060475, dated 06 / 19 / 2026, p. 122 / 752 117 / 355 47).

[00241] chCD123-3, -6, and -14 are the corresponding murine-human chimeric antibodies that possess the variable regions of the murine heavy and light chains and the human constant region sequences. For example, the chimeric antibody chCD123-6 is composed of the mouse HCVR and LCVR of SEQ ID NOs: 28 and 29, respectively, along with the human IgG1 and Kappa constant sequences for heavy and light chains, respectively. See Example 3.

[00242] huCD123-3, -6, and -14 are the corresponding humanized antibodies. When humanization is through CDR grafting of the 6 corresponding murine CDR regions (HC and LC CDR1-3), the letter G immediately follows the clone designation, which in turn is followed by a version number designating the origin of the human light chain and heavy chain variable region sequences. Thus, huCD123-6Gv4.6 refers to the humanized CD123 antibody based on grafting (G) of the 6 CDR regions of the corresponding muCDR123-6 antibody, the human light chain variable region Gv4, and the human heavy chain variable region Gv6. Similarly, -Gv4.7 comprises the human light chain variable region Gv4 and the human heavy chain variable region Gv7; and -Gv1.1 comprises the human light chain variable region Gv1 and the human heavy chain variable region Gv1.

[00243] The three HCVR sequences, huCD123-6Gv1, -Gv6, and -Gv7 are provided in Table 3A (SEQ ID NOs: 32 and 34, with SEQ ID NO: 34 representing both -Gv6 and -Gv7, as they differ only in the 2nd Xaa residue) and their DNA coding sequences in Table 3B (SEQ ID NOs: 62, 64, and 66). The three full-length HC sequences, huCD123-6Gv1, -Gv6, and -Gv7 are provided in Table 5 (SEQ ID NOs: 48 and 50, with SEQ ID NO: 50 representing the full-length -Gv6 and -Gv7, as they differ only in the 2nd Xaa residue) Petition 870260060475, dated 06 / 19 / 2026, p. 123 / 752 118 / 355 residue Xaa).

[00244] The two LCVR sequences, huCD123-6Gv1 and -Gv4, are provided in Table 4A (SEQ ID NOs: 33 and 35), and their DNA coding sequences in Table 4B (SEQ ID NOs: 63 and 65). The two full-length LC sequences, huCD123-6Gv1 and -Gv4, are provided in Table 6 (SEQ ID NOs: 49 and 51).

[00245] When humanization is by coating, the coated heavy chain sequences are called rh immediately after the murine CD123 antibody clone number and are further referred to as one of two versions of the coated sequences, v1.0 or v1.1. Thus, huCD123-6rhv1.0 and -rhv1.1 are heavy chain sequences coated with CDR regions corresponding to the muCD123-6 antibody, with version designations of 1.0 and 1.1, respectively. See HCVR SEQ IDs: 39 and 40 in Table 3A and SEQ ID Nos: 68 and 69 in Table 3B. See also SEQ ID Nos: 59 and 60 of full-length HC in Table 5.

[00246] Similarly, the only version of the coated light chain sequence, huCD123-6rlv1.0, has LCVR SEQ ID NO: 41 in Table 4A, and full-length LC SEQ ID NO: 61 in Table 6.

[00247] An antibody coated with huCD123-6rhv1.0 and huCD1236rlv1.0 is huCD123-6Rv1.0; and an antibody coated with huCD1236rhv1.1 and huCD123-6rlv1.0 is huCD123-6Rv1.1.

[00248] NTS2 or S2 for short refers to an antibody possessing molecularly modified Ser at the N-terminus of the heavy chain. The S2 variant of huCD123-6Gv6 / 7 has the HCVR sequence SEQ ID NO: 38 in Table 3A and the full-length HC protein sequence SEQ ID NO: 53 in Table 5.

[00249] Similarly, NTS3 or S3 for short refers to an antibody possessing a molecularly modified Ser at the N-terminus of the light chain. The S3 variant of huCD123-6Gv4 has the sequence of Petition 870260060475, dated 06 / 19 / 2026, page 124 / 752 119 / 355 LCVR SEQ ID NO: 37 in Table 4A and SEQ ID NO: 58 of the full-length LC protein sequence in Table 6.

[00250] An antibody comprising a molecularly modified N-terminal Ser (S2 or S3) can be conjugated with a drug / cytotoxic agent via the oxidized N-terminal Ser, or via conventional Lys linkage. If the drug linkage is via the oxidized N-terminal Ser, the conjugate name contains a SeriMab designation. If the drug linkage is via Lys, the conjugate name does not contain SeriMab (despite the fact that there is an S2 or S3 designation to signal the presence of molecularly modified Ser at the N-terminal). The particular linkage type will also be apparent based on the reactive group of the cytotoxin. For example, huCD123-6Gv4.7S3-SeriMab-D8 refers to the conjugate between D8 and huCD123-6Gv4.7S3 of humanized CD123 antibody, via the oxidized N-terminal Ser in the light chain.The humanized CD123 antibody has the murine CD123-6 CDR regions grafted on, the human Gv4 LC and Gv7 heavy chain, and the N-terminus of the light chain has a molecularly modified Ser (S3). In contrast, huCD123-6Gv4.7S3-sSPDB-D1 refers to the conjugate between D1 and the same humanized CD123 antibody huCD123-6Gv4.7S3, via Lys linkage through a sulfonated SPDB ligand.

[00251] In certain embodiments, if both the N-terminus of the light chain and the heavy chain contain the molecularly modified Ser, S2S3 or S2S3-SeriMab may appear in the antibody name.

[00252] Certain antibodies of the invention possess a molecularly modified Cys in the CH3 domain of the heavy chain, in a position corresponding to the same Kabat position from the 5th to the last Cys in SEQ ID NO: 54. These HCs or antibodies comprising these HCs bear the designation CysMab. Thus, huCD123-6Gv4.6CysMab is a humanized CD123 antibody possessing CDR regions. Petition 870260060475, dated 06 / 19 / 2026, page 125 / 752 The 120 / 355 grafted muCD123-6 is based on the human Gv4 light chain and Gv6 heavy chain sequences, where a molecularly modified Cys is located in the HC CH3 region at a position corresponding to the 5° to the last Cys in SEQ ID NO: 54. Similarly, its heavy chain sequence is huCD123-6Gv6CysMab. Furthermore, huCD123-6Gv4.6S2-CysMab is otherwise identical but has a molecularly modified Ser at the N-terminus of the heavy chain, and its heavy chain sequence is huCD123-6Gv6S2CysMab.

[00253] The coated antibody described above can be developed to contain an N-terminal Ser in the light chain (S3 variant of the coated antibody) or in the heavy chain (S2 variant of the coated antibody), or both (see below). Alternatively or additionally, the coated antibody may have a molecularly modified Cys in the heavy chain CH3 domain at a position corresponding to the same Kabat position from the 5th to the last Cys of SEQ ID NO: 54 (the CysMab version of the coated antibody). A coated antibody may have combined Cys and N-terminal Ser.

[00254] In conjugates formed between such a CysMab and cytotoxin, however, at least in theory, the cytotoxin can be linked to CysMab via the conventional Cys or Lys linkage. As used in this document, however, without specific indication, a conjugate with a CysMab designation refers to a conjugate between a CysMab and a cytotoxin via the Cys linkage (not the Lys linkage). The particular linkage type will also be apparent based on the reactive group of the cytotoxin.

[00255] Other variations or combinations of the above general nomenclature are also contemplated and will be readily apparent to one skilled in the art. For example, huCD123-6Rv1.1-CysMab is the coated version of huCD123-6 (v1.1) which has a Cys Petition 870260060475, dated 06 / 19 / 2026, page 126 / 752 121 / 355 molecularly modified molecule located in the HC CH3 region at a position corresponding to the 5th to last Cys in SEQ ID NO: 54.

[00256] The antibodies or their antigen-binding fragments of the invention can be conjugated with certain cytotoxic agents, either by linking to the amino group of the Lys side chain, the thiol group of the Cys side chain, or an oxidized N-terminal Ser / Thr. Certain representative (non-limiting) cytotoxic agents described in the descriptive report (including examples) are listed below for illustrative purposes. Note that most compounds such as D1, D2, D4, DGN462, D3, D6, etc., can be sulfonated (not illustrated in this document, but see Figure 17 compound sD1, FIG. 15 compound sDGN462 and FIG. 16 compound sD8) onto one of the indolinobenzodiazepine monomers in certain examples. For compound D5', both indolinobenzodiazepine monomers can be Petition 870260060475, dated 06 / 19 / 2026, page 127 / 752 122 / 355 Compound N° Structure D3 oA 7 / / =\ ° ooo Ξ / / ° \ \ ooo ) >=< °3 O | 3ZI ω ,7 D4 0. ° ? Va hn X Th Ϊ / \ so3h u ífj H i—3 Xa X jf / —\ / OMe MeO N \ O ° Xj D5 oo . n · OO ZI o^>, W -..... >O ZI O. $ yz D5' ? H ! ? H II X1 OH ΰ XJ (I Ί ° / =N ° ~ ' V ' ° N MeO^^xZ'''·^ CX 0 0 XX D6 Ox s ã ^3 nh ΛΊ TTIT ΓΛ 0 ° Vz Petition 870260060475, dated 06 / 19 / 2026, p. 128 / 752 123 / 355 Compound N° Structure D7 Ου ° 7 % ( ° o / po ÍD / ____ Yj o_O o= / 'ΖΞΕ O / z J Vz D8 o H = ? H HN-^YT ü Y NH2 Ί Ί i OH OH (1 D9 H ΜρΠ Meu— ON NH2 ° H íl Ί O Xí f Y '7 1 OMe MeO^^Y^N \ u ° ° u

[00257] Note that several agents differ only slightly due to the different binding chemistry required to bind the cytotoxin to different antibody side chains (i.e., Lys binding, Cys binding, oxidized N-terminal Ser binding). However, these related cytotoxins are given different D designations. See D1 and D4, as well as D2, D5, and D8.

[00258] Conjugates of subject antibodies and cytotoxic agents generally follow the antibody and cytotoxic agent nomenclature as described above.

[00259] For example, huCD123-6Gv4.6-sulfo-SPDB-D1 is a conjugate of the antibody huCD123-6Gv4.6 to compound D1 via a sulfonated SPDB linker, at one or more Lys residues of the antibody. huCD123-6-CX1-1-DM1 is a conjugate of the antibody huCD123-6 conjugated to the cytotoxic agent DM1 via a triglycyl linker called CX1-1 linker, at one or more Lys residues of the Petition 870260060475, dated 06 / 19 / 2026, p. 129 / 752 124 / 355 antibody. See Example 9e.

[00260] A notable exception is the huCD123-6-SeriMabsD1 conjugate shown in FIGS. 7B and 17, in which the short ligand sequence between huCD123-6-SeriMab and the cytotoxin sD1 is not explicitly recited in the conjugate name. Similarly, the huCD123-6-SeriMab-sDGN462 conjugate in FIG. 15 is also an exception to the general rules above. 2. CD123 Liaison Agents

[00261] In a first aspect, the present invention provides agents that bind specifically to CD123 / IL-3Ra, such as human CD123 / IL-3Ra. These agents are generally referred to in this document as CD123 / IL-3Rα binding agents. In certain embodiments, the CD123 / IL-3Ra binding agents are antibodies or antigen-binding fragments thereof (or antibodies for simplicity), their immunoconjugates or their polypeptides.

[00262] Amino acid and nucleotide sequences for human and other species of CD123 / IL-3Rα are known in the art. For example, the human CD123 / IL-3Rα variant 1 splice protein sequence as described in NCBI RefSeq NP_002174 is reproduced below: MVLLWLTLLL IALPCLLQTK EDPNPPITNL RMKAKAQQLT WDLNRNVTDI ECVKDADYSM PAVNNSYCQF GAISLCEVTN YTVRVANPPF STWILFPENS GKPWAGAENL TCWIHDVDFL 121 SCSWAVGPGA PADVQYDLYL NVANRRQQYE CLHYKTDAQG TRIGCRFDDI SRLSSGSQSS 181 HILVRGRSAA FGIPCTDKFV VFSQIEILTP PNMTAKCNKT HSFMHWKMRS HFNRKFRYEL 241 QIQKRMQPVI TEQVRDRTSF QLLNPGTYTV QIRARERVYE FLSAWSTPQR FECDQEEGAN Petition 870260060475, dated 06 / 19 / 2026, p. 130 / 752 125 / 355 301 TRAWRTSLLI ALGTLLALVC VFVICRRYLV MQRLFPRIPH MKDPIGDSFQ NDKLVVWEAG 361 KAGLEECLVT EVQVVQKT (SEQ ID NO: 36)

[00263] The sequence above shows the CD123 / IL-3R alpha precursor chain protein, which is composed of 378 amino acids, containing the extracellular domain (residues 1-306, including an 18-residue N-terminal signal peptide), a 20-amino acid transmembrane domain, and a small 52-amino acid cytoplasmic tail.

[00264] The nucleic acid sequence of variant 1 of splice of Human CD123 / IL-3Ra as represented in NCBI RefSeq NM_002183 is reproduced below: GTCAGGTTCA TGGTTACGAA GCTGCTGACC CCAGGATCCC AGCCCGTGGG AGAGAAGGGG GTCTCTGACA GCCCCCACCC CCAGATCCTT ATTGGGTCTG AGTTTCAGGG 121 GTGGGGCCCC AGCTGGAGGT CTCAATCGGG GAGTACAACC TTCGGTTTCT 181 CTTCGGGGAA AGCTGCTTTC GGAAGATATC AGAAACATCC TAGGATCAGG 241 ACACCCCAGA TCTTCTCAAC AAGGCTGTTT CTTCCACACA GTACTTTGAT 301 CTCCATTTAA GCAGGCACCT TTCCGGAGCT GCGTTCCCGA TGGTCCTCCT 361 TTGGCTCACG CTGCTCCTGA CTGTCTCCTG CAAACGAAGG AAGATCCAAA 421 CCCACCAATC ACGAACCTAA AAAGGCTCAG CAGTTGACCT GGGACCTTAA 481 CAGAAATGTG ACCGATATCG AGACGCCGAC TATTCTATGC CGGCAGTGAA CTCCCCACTG TATAAAACAG AGCGCACACG TGGAACCACG CTGTCCTGCG TCGCCCTGCC GGATGAAAGC AGTGTGTTAA 541 CAATAGCTAT TGCCAGTTTG GAGCAATTTC CTTATGTGAA Petition 870260060475, dated 06 / 19 / 2026, page 131 / 752 126 / 355 GTGACCAACT ACACCGTCCG 601 AGTGGCCAAC CCACCATTCT CCTCTTCCCT GAGAACAGTG GGAAGCCTTG 661 GGCAGGTGCG GAGAATCTGA TCATGACGTG GATTTCTTGA GCTGCAGCTG 721 GGCGGTAGGC CCGGGGGCCC CCAGTACGAC CTGTACTTGA ACGTTGCCAA 781 CAGGCGTCAA CAGTACGAGT CAAAACGGAT GCTCAGGGAA CACGTATCGG 841 GTGTCGTTTC GATGACATCT CAGCGGTTCT CAAAGTTCCC ACATCCTGGT 901 GCGGGGCAGG AGCGCAGCCT CTGCACAGAT AAGTTTGTCG TCTTTTCACA CCACGTGGAT CCTGCTGGAT CCGCGGACGT GTCTTCACTA CTCGACTCTC TCGGTATCCC 961 GATTGAGATA TTAACTCCAC CCAACATGAC TGCAAAGTGT AATAAGACAC ATTCCTTTAT 1021 GCACTGGAAA ATGAGAAGTC CAAATTTCGC TATGAGCTTC AGATACAAAA 1081 GAGAATGCAG CCTGTAATCA CAGAGACAGA ACCTCCTTCC AGCTACTCAA 1141 TCCTGGAACG TACACAGTAC CCGGGAAAGA GTGTATGAAT TCTTGAGCGC 1201 CTGGAGCACC CCCCAGCGCT CCAGGAGGAG GGCGCAAACA CACGTGCCTG 1261 GCGGACGTCG CTGCTGATCG GCTGCTGGCC CTGGTCTGTG TCTTCGTGAT 1321 CTGCAGAAGG TATCTGGTGA CTTTCCCCGC ATCCCTCACA TGAAAGACCC 1381 CATCGGTGAC AGCTTCCAAA GGTGGTCTGG GAGGCGGGCA AAGCCGGCCT 1441 GGAGGAGTGT CTGGTGACTG ATTTCAATCG CAGAACAGGT AAATAAGAGC TCGAGTGCGA CGCTGGGGAC TGCAGAGACT ACGACAAGCT AAGTACAGGT Petition 870260060475, of 19 / 06 / 2026, p. 132 / 752 127 / 355 CGTGCAGAAA ACTTGAGACT GGGGTTCAGG 1501 GCTTGTGGGG GTCTGCCTCA ATCTCCCTGG CCGGGCCAGG CGCCTGCACA GACTGGCTGC 1561 TGGACCTGCG CACGCAGCCC AGGAATGGAC ATTCCTAACG GGTGGTGGGC ATGGGAGATG 1621 CCTGTGTAAT TTCGTCCGAA GCTGCCAGGA AGAAGAACAG AACTTTGTGT GTTTATTTCA 1681 TGATAAAGTG ATTTTTTTTT TTTTAACCCA AAA (SEQ ID NO: 52)

[00265] CD123 / IL-3Ra protein and nucleic acid sequences from other non-human species can be easily retrieved from public databases, such as GenBank, using sequence search tools known in the art (such as NCBI BLASTp or BLASTn) and the above protein and nucleic acid sequences as query sequences, respectively.

[00266] These sequences from non-human species can be aligned with human sequences using any of the many sequence alignment tools recognized in the art, such as those described in this document and above, so that any amino acid or nucleotide residues corresponding to any given human sequences or sequence regions can be easily obtained.

[00267] Thus, one aspect of the invention provides an antibody or its antigen-binding fragment that: (a) binds an epitope to amino acids 101 to 346 of the human CD123 antigen and (b) inhibits IL3-dependent proliferation in antigen-positive TF-1 cells.

[00268] In some embodiments, an anti-CD123 / IL-3Ra antibody or its antigen-binding fragment can specifically bind to an epitope of SEQ ID NO: 36. In certain embodiments, the epitope is within a region corresponding to residues 101-346 of Petition 870260060475, dated 06 / 19 / 2026, p. 133 / 752 128 / 355 Human CD123 / IL-3Ra. In certain embodiments, the epitope is within a region corresponding to residues 101-204 of SEQ ID NO: 36. In certain other embodiments, the epitope is within a region corresponding to residues 205-346 of SEQ ID NO: 36. In certain embodiments, the epitope is not within a region corresponding to residues 1-100 of human CD123 / IL-3Ra.

[00269] In certain embodiments, CD123 / IL3Ra binding agents (e.g., antibodies) inhibit IL3-dependent signaling, such as IL-3-dependent proliferation of CD123-positive TF-1 cells. While not wishing to be bound by any particular theory, the CD123 / IL-3Rα binding agents (e.g., antibodies) of the invention bind to CD123, such as within a CD123 region corresponding to residues 101-346 (e.g., residues 101-204 or 205-346) of human CD123 / IL-3Rα and prevent, reduce, diminish, or inhibit productive binding between CD123 and the IL-3 ligand and / or productive binding between CD123 and CD131 of the common beta chain, leading to reduced or abolished IL-3-dependent signaling.

[00270] In a related aspect, the invention provides an antibody or antigen-binding fragment thereof that: (a) binds an epitope within amino acids 1 to 100 of human CD123 antigen and (b) inhibits IL3-dependent proliferation in antigen-positive TF-1 cells, with an IC50 value of 0.1 nM or less (e.g., 0.08 nM, 0.05 nM, 0.03 nM).

[00271] In certain embodiments, binding by the CD123 / IL-3Rα binding agents (e.g., antibodies) of the invention inhibits (e.g., preferentially inhibits) the proliferation of leukemic stem cells (LSCs), leukemic progenitors (LPs), or leukemic blasts, but does not substantially inhibit the proliferation of normal hematopoietic stem cells (HSCs). Petition 870260060475, dated 06 / 19 / 2026, page 134 / 752 129 / 355

[00272] Inhibition of cell proliferation can be conducted using any standard assays known in the art, including, but not limited to, flow cytometry. For example, HSCs, LSCs, normal LPs, and leukemic blasts can be separated using flow cytometry based on the difference in the expression of cell surface markers, and the relative number of surviving or remaining cells after incubation with the test agents can be measured and compared quantitatively.

[00273] The inhibition of cell proliferation of leukemic LSCs, LPs, or blasts compared to normal HSCs can also be assayed using an in vitro potency assay in primary cancer cells, such as primary AML cells. For example, AML cells (or normal human bone marrow samples containing normal HSCs) can be exposed to various concentrations of the subject's anti-CD123 antibodies, their antigen-binding fragments, their immunoconjugates, or a polypeptide comprising the antibodies or antigen-binding fragments for 24 hours. Non-targeted (isotype-matched) antibodies, or immunoconjugate controls (ADCs) can also be used in the assay. Samples can be divided into a short-term liquid culture assay (STLC) to measure cytotoxicity against leukemic LSCs, LPs, or blasts; and a long-term liquid culture assay (LTLC) to measure the effect on normal LSCs and HSCs.STLC can be used to measure colony-forming units from 10-14 days in cells, for example, following plating on MethoCult H4230 semi-solid medium (Stemcell technologies). LTLC assays can be performed similarly with the addition of growth factors for long-term culture of 5-7 weeks. In both assays, colonies can be counted to determine colony-forming units per number of cells initially plated. Petition 870260060475, dated 06 / 19 / 2026, page 135 / 752 130 / 355 LTLC can be further analyzed for the presence of molecular cancer markers (e.g., AML) using PCR or FISH or both.

[00274] In certain embodiments, the antibody or its antigen-binding fragment binds to cells positive for human CD123 antigen with a dissociation constant (Kd) of 0.3 nM or less. In certain embodiments, the antibodies or their antigen-binding fragments bind to human CD123 with a Kd between 0.05 and 0.3 nM, or between 0.05 and 0.2 nM, or between 0.05 and 0.1 nM, or between 0.01 nM and 0.3 nM, or between 0.01 nM and 0.2 nM, or between 0.01 nM and 0.1 nM.

[00275] In certain embodiments, antibodies or their antigen-binding fragments bind to cynomolgus monkey CD123. In certain embodiments, antibodies or their antigen-binding fragments bind to cynomolgus monkey CD123 with a Kd between 0.05 and 0.3 nM, or between 0.05 and 0.2 nM, or between 0.05 and 0.1 nM.

[00276] In certain embodiments, antibodies or their antigen-binding fragments bind to human and cynomolgus monkey CD123 with substantially similar binding affinity. In certain embodiments, antibodies or their antigen-binding fragments bind to human and cynomolgus monkey CD123 with Kd between 0.05 and 0.3 nM, or between 0.05 and 0.2 nM, or between 0.05 and 0.1 nM.

[00277] In certain modalities, the Kd value is based on cell-based binding assay. In certain modalities, the Kd value is measured by flow cytometry. In certain modalities, the Kd value is measured by surface plasma resonance (such as, for example, using the BIOCORE™ surface plasma resonance system). In certain modalities, the Kd value is measured by radioimmunoassay (RIA). In certain modalities, Kd is measured by any other method recognized by the art. Petition 870260060475, dated 06 / 19 / 2026, p. 136 / 752 131 / 355

[00278] In certain embodiments, the antibody or its antigen-binding fragment inhibits at least 50% of IL3-dependent proliferation in antigen-positive TF-1 cells at a concentration of 0.5 nM or lower.

[00279] In certain embodiments, CD123 / IL3Ra binding agents are CD123 / IL-3Ra antibodies or their antigen-binding fragments comprising a heavy chain variable region (HCVR) and a light chain variable region (LCVR), each comprising three CDR regions (e.g., CDR1-CDR3 for HCVR and CDR1-CDR3 for LCVR), wherein the composite CDRs for HCVR and LCVR are one of the sequences provided in Tables 1 and 2 below. Petition 870260060475, dated 06 / 19 / 2026, page 137 / 752 132 / 355 Table 1 Amino acid sequences CDR of the variable region of the heavy chain Antibody Alt Name VH-CDR1 VH-CDR2 VH-CDR3 CD123-3 CD123Mu -3 SYVMH (SEQ ID NO:1) YIKPYKDGTK (SEQ ID NO:2) EGENGYYDAMDY (SEQ ID NO:4) YIKPYKDGTKYNEKFKG (Kabat) (SEQ ID NO:3) CD123-6 CD123Mu -6 SSIMH (SEQ ID NO:5) YIKPYNDGTK Murine + Grafted (SEQ ID NO:6) EGGNDYYDTMDY (SEQ ID NO:11) YIRPYNDGTR (resurrected version 1.0) (SEQ ID NO: 7) YIKPYNDGTKYNEKFKG (Murine Kabat + Grafted) (SEQ ID NO: 8) YIRPYNDGTRYNQKFQG(Kabat - resurrected v1. 0) (SEQ ID NO:9) Petition 870260060475, dated 06 / 19 / 2026, p. 138 / 752 133 / 355 YIKPYNDGTKYNQKFQG (Kabat - resurfaced v1. 1) (SEQ ID NO:10) CD123-14 CD123Mu -14 NYAMS (SEQ ID NO:12) TINSGGSFTY (SEQ ID NO:13) QSEAYYGYDKRT (SEQ ID NO:15) QSEAYYGYDKRTWFAY (SEQ ID NO:70) TINSGGSFTYYPDSVKG (Kabat) (SEQ ID NO:14) Petition 870260060475, dated 06 / 19 / 2026, p. 139 / 752 134 / 355 Table 2 Amino acid sequences of the CDR of the variable region of the light chain Anticorpo Alt Nome VL-CDR1 VL-CDR2 VL-CDR3 CD123-3 CD123Mu- 3 KASQDINKYIA (SEQ ID NO:16) YTSTLQP (SEQ ID NO:17) LQYDNLLYT (SEQ ID NO:18) CD123-6 CD123Mu- 6 KASQDINSYLS (SEQ ID NO:19) RVNRLVD (SEQ ID NO:21) LQYDAFPYT (SEQ ID NO:22) RASQDINSYLS Humanizado (SEQ ID NO:20) RASQDINSYLA (SEQ ID NO:72) RVNRLVS (SEQ ID NO:71) CD123- 14 CD123Mu- 14 RASQSVGTSIH (SEQ ID NO:23) YASESIS (SEQ ID NO:24) QQSKSWPLT (SEQ ID NO:25)

[00280] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) at least one variable heavy chain region or a fragment thereof comprising three sequence complementarity-determining (CDR) regions CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 1, 5 and 12, CDR2 is selected from the group consisting of SEQ ID NOs: 2-3, 6-10 and 13-14, and optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 4, 11, 15 and 70; (b) at least one variable light chain region or a fragment thereof comprising three sequence complementarity-determining regions (CDRs) CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected Petition 870260060475, dated 06 / 19 / 2026, p. 140 / 752 135 / 355 from the group consisting of SEQ ID NOs: 16, 19-20, 23 and 72, CDR2 is selected from the group consisting of SEQ ID NOs: 17, 21, 24 and 71 and, optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 18, 22 and 25.

[00281] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) at least one variable heavy chain region or a fragment thereof comprising three sequence complementarity-determining (CDR) regions CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 1, 5 and 12, CDR2 is selected from the group consisting of SEQ ID NOs: 2-3, 6-10 and 13-14, and optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 4, 11 and 15;(b) at least one variable light chain region or a fragment thereof comprising three sequence complementarity-determining (CDR) regions CDR1, CDR2 and CDR3, respectively, wherein, with the exception of 1, 2 or 3 conservative amino acid substitutions, CDR1 is selected from the group consisting of SEQ ID NOs: 16, 19-20 and 23, CDR2 is selected from the group consisting of SEQ ID NOs: 17, 21 and 24 and, optionally, CDR3 is selected from the group consisting of: SEQ ID NOs: 18, 22 and 25.

[00282] In certain embodiments, the conservative amino acid substitutions comprise a substitution of a Lys in a CDR by an Arg (such as the Lys-to-Arg substitutions in SEQ ID NOs: 6 and 7, 8 and 9, and 19 and 20). In certain embodiments, the antibody is a humanized CDR-grafted antibody comprising mouse CDR regions, and wherein one or more (e.g., 1, 2, 3, 4, 5, 6, 7, or 8) of the heavy chain region and / or the light chain region, vernier zone residues of the antibody are of mouse origin. Petition 870260060475, dated 06 / 19 / 2026, pp. 141 / 752 136 / 355

[00283] In certain embodiments, anti-CD123 / IL-3Ra antibodies and antigen-binding fragments thereof comprise: a) a variable immunoglobulin heavy chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 1, a CDR2 having an amino acid sequence presented in SEQ ID NO: 2 or 3 and, optionally, a CDR3 having an amino acid sequence presented in SEQ ID NO: 4; and 2) an immunoglobulin light chain variable region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 16, a CDR2 having an amino acid sequence presented in SEQ ID NO: 17 and, optionally, a CDR3 having an amino acid sequence presented in SEQ ID NO: 18. In certain embodiments, the CDR2 of the heavy chain variable region is SEQ ID NO: 2. In certain embodiments, the CDR2 of the heavy chain variable region is SEQ ID NO: 3.

[00284] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 5, a CDR2 having an amino acid sequence presented in SEQ ID NO: 6, 7, 8, 9 or 10 and, optionally, a CDR3 having an amino acid sequence presented in SEQ ID NO: 11; and 2) a variable immunoglobulin light chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 19 or 20, a CDR2 having an amino acid sequence presented in SEQ ID NO: 21 and, optionally, a CDR3 having an amino acid sequence presented in SEQ ID NO: 22. In certain embodiments, the CDR2 of the variable heavy chain region is SEQ ID NO: 6 and the CDR1 of the variable light chain region is SEQ ID NO: 19. In certain embodiments, the Petition 870260060475, dated 06 / 19 / 2026, pp. 142 / 752 137 / 355 The CDR2 of the variable region of the heavy chain is SEQ ID NO: 7 and the CDR1 of the variable region of the light chain is SEQ ID NO: 19. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 8 and the CDR1 of the variable region of the light chain is SEQ ID NO: 19. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 9 and the CDR1 of the variable region of the light chain is SEQ ID NO: 19. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 10 and the CDR1 of the variable region of the light chain is SEQ ID NO: 19. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 6 and the CDR1 of the variable region of the light chain is SEQ ID NO: 20. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 7 and the CDR1 of the variable region of the light chain is SEQ ID NO: 19. The CDR2 of the light chain is SEQ ID NO: 20. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 8 and the CDR1 of the variable region of the light chain is SEQ ID NO: 20.In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 9 and the CDR1 of the variable region of the light chain is SEQ ID NO: 20. In certain embodiments, the CDR2 of the variable region of the heavy chain is SEQ ID NO: 10 and the CDR1 of the variable region of the light chain is SEQ ID NO: 20. For each pair of combinations of heavy chain variable region CDR2 with light chain variable region CDR1 above, the heavy chain variable region CDR1 and 3 are SEQ ID NOs: 5 and 11, respectively, and the light chain variable region CDR2 and 3 are SEQ ID NOs: 21 and 22, respectively.

[00285] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 12, a CDR2 having an amino acid sequence presented in SEQ ID NO: 13 or 14 and, optionally, a CDR3 having an amino acid sequence presented in SEQ ID NO:. Petition 870260060475, dated 06 / 19 / 2026, page 143 / 752 138 / 355 15; and 2) a variable region of the immunoglobulin light chain comprising a CDR1 having an amino acid sequence presented in SEQ ID NO: 23, a CDR2 having an amino acid sequence presented in SEQ ID NO: 24 and, optionally, a CDR3 having an amino acid sequence presented in SEQ ID NO: 25. In certain embodiments, CDR2 of the variable region of the heavy chain is SEQ ID NO: 13. In certain embodiments, CDR2 of the variable region of the heavy chain is SEQ ID NO: 14.

[00286] In certain embodiments, the CDR1 sequences of the light and heavy chains of one antibody (such as SEQ ID NOs: 5 and 19) can be combined with CDR2 sequences of the light and heavy chains of another antibody (such as SEQ ID NOs: 2 and 17) and optionally can be combined with CDR3 sequences of the light and heavy chains of the same antibody (e.g., SEQ ID NOs: 4 and 18, or 11 and 22) or another antibody (e.g., SEQ ID NOs: 15 and 25). All possible combinations based on the SEQ ID NOs: 125 in Table 1, particularly those pertaining to the same antibody number (e.g., all six CDRs of the light and heavy chains come from CD123-3, or from CD123-6, or from CD123-14) are contemplated here without exhaustively enumerating all specific combinations.

[00287] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments have conserved amino acid substitutions at 1, 2, or 3 consecutive residues in any one or more of the above CDR sequences. That is, in some embodiments, the antibodies in question and their antigen-binding fragments may have conserved amino acid substitutions at 1, 2, or 3 consecutive residues in any one or more of the SEQ ID NOs: 125.

[00288] In certain modes, the CD123 / IL linking agents Petition 870260060475, dated 06 / 19 / 2026, p. 144 / 752 139 / 355 3Ra are CD123 / IL-3Ra antibodies or antigen-binding fragments comprising a heavy chain variable region (HCVR) and a light chain variable region (LCVR), wherein the HCVR and LCVR are some of the sequences provided in Tables 3A and 4A below. Selected corresponding nucleic acid sequences encoding the HCVR and LCVR are in Tables 3B and 4B. Table 3A Amino acid sequences of the Variable Region of the Chain Heavy Antibody Alt Name Amino Acid Sequence VH (SEQ ID NO) CD123-3 CD123Mu-3 EFQLQQSGPEVVKPGASVKMSCKASGYT FTSYVMHWMKQKPGQGLEWIGYIKPYKD GTKYNEKFKGKATLISDKPSSTAYMELSSL TSEDSAVYYCAREGENGYYDAMDYWGQ GTSVTVSS (SEQ ID NO:26) CD123-6 CD123Mu-6 EFQLQQSGPELVKPGASVKMSCKASGYIF TSSIMHWMKQKPGQGLEWIGYIKPYNDGT KYNEKFKGKATLTSDKSSSTANMELNSLT SEDSAVYYCAREGGNDYYDTMDYWGQG TSVTVSS (SEQ ID NO:28) CD123-14 CD123Mu-14 EVKLVESGGDLVKPGGSLKLSCAASGFTF SNYAMSWVRQNSEKRLEWVATINSGGSF TYYPDSVKGRFTISRDNAKDSLYLQMSSL NSEDTAMYYCARQSEAYYGYDKRTWFAY WGQGTLVTVSS (SEQ ID NO:30) huCD123- 6Gv1 QVQLVQSGAEVKKPGASVKVSCKASGYG FTSSIMHWVRQAPGQGLEWMGYIKPYND GTKYNEKFKGRVTMTRDTSTSTVYMELSS LRSEDTAVYYCAREGGNDYYDTMDYWG QGTLVTVSS (SEQ ID NO:32) huCD123- 6Gv6 / 7 QXQLVQSGAEVKKPGASVKVSCKASGYIF TSSIMHWVRQAPGQGLEWIGYIKPYNDGT KYNEKFKGRATLTSDRSTSTAYMELSSLR Petition 870260060475, dated 06 / 19 / 2026, page 145 / 752 140 / 355 SEDTAVYYCAREGGNDYYDTMDYWGQG TLVTVSS (SEQ ID NO:34) huCD123- 6Gv6 / 7-NTS2 SXQLVQSGAEVKKPGASVKVSCKASGYIF TSSIMHWVRQAPGQGLEWIGYIKPYNDGT KYNEKFKGRATLTSDRSTSTAYMELSSLR SEDTAVYYCAREGGNDYYDTMDYWGQG TLVTVSS (SEQ ID NO:38) huCD123- 6rhv1.0 QVQLVQSGAEVVKPGASVKMSCKASGYT FTSSIMHWMKQKPGQGLEWIGYIRPYNDG TRYNQKFQGKATLTSDRSSSTANMELNSL TSEDSAVYYCAREGGNDYYDTMDYWGQ GTSVTVSS (SEQ ID NO:39) huCD123-6rhv1.1 *In all the sequences above where the 2nd residue of terminal N is X (or Xaa), for example SEQ ID NOs: 34 and 38, X is F for Gv6 sequences, while X is V for Gv7 sequences. Petition 870260060475, dated 06 / 19 / 2026, page 146 / 752 141 / 355 Table 3B Nucleic Acid Sequences of the Variable Region of Selected Heavy Chain Antibody VH DNA sequence (SEQ ID NO) huCD123- 6VhGv1 AAGCTTGCCACCATGGGATGGTCCTGCATTATCCT GTTCCTTGTAGCAACTGCAACAGGAGTCCACAGCC AGGTCCAACTGGTGCAGTCCGGGCCGAGGTGAA GCCAGCGGCTATGGTTTTACCAGCTCAATCATGCA CTGGGTCAGGCAAGCCCCAGGACAGGGTCTCGAA TGGATGGGATACATTAAGCCTTACAATGGTAC AAAATATAATGAAAATTAAGGGTCGTGTTACCAT GACAAGGGATACATCAACTAGCACTGCTATGGAT AACTGAGCTCTCTCAGGTCCGAGGATACTGCAGTA TATTACTGCGCCCGGGAGGGAGGCAACGACTATTA CGACACCATGGACTATTGGGGGCAGGGCACACTG GTTACTGTATCCAGGCGCCTCTACTAAGGGGCCC (SEQ ID NO:62) huCD123- 6Vh6VhGv AAGCTTGCCACCATGGGCTGGTCCTGTATCATCCT GTTCCTCGTTGCAACAGCAACTGGCGTGCACAGCC AGTTCCAGCTTGTGCAGAGTGGCGCCGAAGTCAA GAAACCAGGCGCTAGTGTCAAGGTGTCCTGTAAG GCATCAGGCTACATCI IIACCAGCTCCATCATGCA TTGGGTCAGACAGGCTCCTGGACAGGGCCTGGAG TGGATTGGGTATATCAAGCCATACAATGGGAC AAAATACAATGAAAAGTTTAAAGGGCGAGCCACTC TGACATCTGATCGGAGTACAAGCACTGCCTACATG GAATTGAGCTCACTGCGGTCCGAGAGCTGCTGCT GTATTATTGCGCTCGGGAGGGAGGGAACGACTAC TACGATACCATGGACTACTGGGGCCAGGGCACCCTGGTTACCGTCAGCAGCGCTTCCACTAAGGGCCC (SEQ ID NO:64) Petition 870260060475, dated 06 / 19 / 2026, p. 147 / 752 142 / 355 huCD123- aagcttgccaccatgggctggtcctgtatcatcct 6VhGv7 gttcctcgttgcaacagcaactggcgtgcacagcc aggtccaacttgtgcagagtggcgccgaagtcaa gaaaccaggcgctagtgtcaaggtgtcctgtaag gcatcaggctacatci iiaccagctccatcatgca ttgggtcagacaggctcctggacagggcctggag tggattgggtatatcaagccatacaatgatgggac aaaatacaatgaaaagtttaaagggcgagccactc tgacatctgatcggagtacaagcactgcctacatg gaattgagctcactgcggtccgaagacactgctgt gtattattgcgctcgggagggagggaacgactac tacgataccatggactactggggccagggcaccc tggttaccgtcagcagcgcttccactaagggccc (SEQ ID NO:66) huCD123- aagcttgccaccatggggtggagctgcattattct 6VHrhv1.0 gttcttggtcgccaccgcaactggcgtccactctc aggtccagctcgtccagtctggggcagaagtggt caagcccggtgcatctgtgaaaatgtcctgcaaag ctagcgggtatacattcacatctagtatcatgcatt ggatgaaacagaagcctggccagggtctggagtg gataggatatatcaggccttacaacgatggcactc gatacaaccaaaagttccagggtaaagctacactg acctcagaccgctcaagcagtacagcaaacatgga actgaacagtcttacctctgaggacagtgccgiii actattgcgccagggagggtggcaatgactactat gatactatggactactggggacagggtacctctgt aacagtttcaagcgccagcactaagggccc (SEQ ID NO:68) Petition 870260060475, dated 06 / 19 / 2026, pp. 148 / 752 143 / 355 huCD123- 6VHrhv1.1 AAGCTTGCCACCATGGGCTGGTCTTGTATTATTCT GTTTCTGGTGGCCACCGCAACAGGCGTTCACAGTC AATTCCAGCTGGTCCAGTCCGGCGCCGAGGTTGT CAAACCTGGTGCCAGCGTAAAGATGTCTTGCAAAG CTAGCGGCTATACIIICACTTCTTCAATTATGCACT GGATGAAGCAAAAGCCTGGACAGGGCCTGGAATG GATCGGCTACATTAAACCTTATAACGACGGCACAA AGTACAATCAGAAGTTCCAAGGAAAGGCAACCCTG ACCTCAGACAAGTCTTCATCCACTGCCAACATGGA ACTTAATAGTCTTACCTCTGAGGATTCCGCTGTCTA TTATTGCGCTCGGGAGGGGGGGAACGACTATTAC GACACCATGGACTACTGGGGACAGGGCACCAGTG TTACCGTGTCCAGCGCTAGCACCAAGGGCCC (SEQ ID NO:69) *Bases in bold mark the first codon of the amino acid sequence in the mature variable region. Table 4A Amino acid sequences of the Variable Region of the Light Chain Antibody Alt Name Amino Acid Sequence VL (SEQ ID NO) CD123-3 DIQMTQSPSSLSASLGGKVTITCKASQDINK YIAWYQHKPGKGPRLLIHYTSTLQPGIPSRF SGSGSGRDYSFSISNLEPEDIATYYCLQYD NLLYTFGGGTKLELKR(SEQ ID NO:27) CD123-6 DIKMTQSPSSMYASLGERVTITCKASQDINS YLSWFQQKPGKSPKTLIYRVNRLVDGVPSR FSGSGSGQDYSLTISSLEYEDMGIYYCLQY DAFPYTFGGGTKLEIKR(SEQ ID NO:29) CD123-14 DILLTQSPAILSVSPGTRVSFSCRASQSVGT SIHWYQQRPNGFPRLLIKYASESISGIPSRF SGSGSGTDFTLNINSVESEDIADYYCQQSK SWPLTFGAGTKLELKR(SEQ ID NO:31) Petition 870260060475, dated 06 / 19 / 2026, page 149 / 752 144 / 355 huCD123- 6Gv1 DIQMTQSPSSLSASVGDRVTITCRASQDINS YLAWFQQKPGKAPKSLIYRVNRLVSGVPSR FSGSGSGTDFTLTISSLQPEDFATYYCLQYD AFPYTFGQGTKVEIKR (SEQ ID NO:33) huCD123- 6Gv4 DIQMTQSPSSLSASVGDRVTITCRASQDINS YLSWFQQKPGKAPKTLIYRVNRLVDGVPSR FSGSGSGNDYTLTISSLQPEDFATYYCLQY DAFPYTFGQGTKVEIKR (SEQ ID NO:35) huCD123- 6Gv4-NTS3 SIQMTQSPSSLSASVGDRVTITCRASQDINS YLSWFQQKPGKAPKTLIYRVNRLVDGVPSR FSGSGSGNDYTLTISSLQPEDFATYYCLQY DAFPYTFGQGTKVEIKR (SEQ ID NO:37) huCD123- 6rlv1.0 DIQMTQSPSSMSASVGERVTITCRASQDIN SYLSWFQQKPGKSPKTLIYRVNRLVDGVPS RFSGSGSGQDYSLTISSLEPEDMGIYYCLQ YDAFPYTFGQGTKLEIKR (SEQ ID NO:41) Table 4B Nucleic Acid Sequences of the Variable Region of Selected Lightweight Chain Antibody Alt Name DNA sequence VL (SEQ ID NO) huCD123-6 VlGvI GAATTCGCCACCATGGGTTGGTCTTGTAT AATCCTGTTCCTGGTCGCTACCGCAACAG GGGTTCACTCAGACATCCAGATGACCCA GAGTCCCTCTTCTGAGCTTCTGACCTTGGGGGGGGCCG ATCCCAGGACATCAATTCTTACCTGGCTT GGTTCCAGCAGAAGCCCGGAAAAGCCCC TAAATCTCTCAIIIACCGGGTAAACCGTT TGGTCTCCGGAGTGCCTTCAAGG iiiAGT GGATCTGGATCAGGTACAGACTTCACTCT CACCATAAGCAGCCTGCAACCAGAGGAT TTCGCACCTTGATTGATTGATT CGCCTTCCCTTACACT TTCGGGCAGGGG Petition 870260060475, of 19 / 06 / 2026, p. 150 / 752 145 / 355 ACCAAAGTGGAAATAAAGCGTACG (SEQ ID NO:63) huCD123-6 VlGv4 GAATTCGCCACCATGGGTTGGTCCTGTAT CATCCTCIIICTGGTGGCAACTGCAACCG GCGTCCATAGCGACATTCAGATGACACA GTCTCCTTCTTCCCTGAGCGCCAGCGTC GGGGACCGCGTGACTATCACATGTCGGG CCTCCCAGGACATTAACTCTTACCTCTCC TGGTTCCAGCAGAAGCCTGGGAAAGCCC CAAAGACACTGATATACAGGGTAAATCGT TTGGTTGACGGTGTACCATCACGATTTTC CGGTAGTGGGTCTGGAAACGATTACACT CTCACAATTAGCAGCCTGCAACCAGAGG ACTTTGCAACATACTATTGCCTGCAGTAC GATGCTTTTCCTTATACCTTCGGTCAGGG TACCAAGGTGGAAATTAAACGTACG (SEQ ID NO:65) huCD123- 6VL(resurfaced) GAATTCGCCACCATGGGCTGGTCATGTAT TATCCTGTTTCTGGTTGCAACCGCAACAG GAGTACACTCTGATATCCAGATGACTCAG TCTCCCTCTTCTATGTCTGCTTCTGTGGG AGAGAGAGTCACCATCACCTGTCGCGCT TCCCAAGATATTAATAGCTATCTGTCTTG GTTCCAACAGAAACCTGGCAAATCACCCA AGACTCTGAIIIATCGGGTTAACCGCCTG GTGGACGGTGTGCCTTCACGCTTCTCCG GCAGCGGTAGTGGACAAGACTATAGCCT GACAAIIICTTCTCTTGAACCCGAGGACA TGGGAATCTACTATTGCTTGCAGTATGAC GCIIII CCπATACAπCGGCCAGGGCAC AAAGCIGGAAAICAAACGIACG (SEQ ID NO:67) *Bases in bold mark the first codon in the sequence of Petition 870260060475, dated 06 / 19 / 2026, pp. 151 / 752 146 / 355 amino acids from the mature variable region

[00289] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: (a) a VH sequence at least 95% identical to a VH sequence reference selected from a group having amino acid sequences represented by SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38); and / or (b) a VL sequence at least 95% identical to a VL sequence reference selected from the group having amino acid sequences represented by SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37).

[00290] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: (a) a VH sequence at least 96% identical to a VH sequence reference selected from a group having amino acid sequences represented by SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38); and / or (b) a VL sequence at least 96% identical to a VL sequence reference selected from the group having amino acid sequences represented by SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37).

[00291] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: (a) a VH sequence at least 97% identical to a VH sequence reference selected from a group having amino acid sequences represented by SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38); and / or (b) a Vl sequence at least 97% identical to a Vl sequence reference selected from the group having amino acid sequences represented by SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and Petition 870260060475, dated 06 / 19 / 2026, pp. 152 / 752 147 / 355 37).

[00292] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: (a) a Vh sequence at least 98% identical to a VH sequence reference selected from a group having amino acid sequences represented by SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38); and / or (b) a VL sequence at least 98% identical to a Vl sequence reference selected from the group having amino acid sequences represented by SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37).

[00293] In certain embodiments, anti-CD123 antibodies and their antigen-binding fragments comprise: (a) a VH sequence at least 99% identical to a VH sequence reference selected from a group having amino acid sequences represented by SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38); and / or (b) a VL sequence at least 99% identical to a VL sequence reference selected from the group having amino acid sequences represented by SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37).

[00294] In certain embodiments, the CD123 / IL-3Ra antibody / antigen-binding fragment has a certain percentage of sequence identity for SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (preferably SEQ ID NOS: 26, 28, 30, 32, 34 and 38) and / or 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37) differs from SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38) and / or 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37) only by conservative amino acid substitutions, such as 1, 2 or 3 conservative amino acid substitutions. In certain Petition 870260060475, dated 06 / 19 / 2026, pp. 153 / 752 148 / 355 modalities, conservative amino acid substitutions are substitutions of 1, 2, or 3 consecutive amino acids in one or more CDR regions of the heavy and / or light chains.

[00295] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: (a) a Vh sequence identical to a Vh sequence reference selected from a group having amino acid sequences represented by SEQ ID NOS: 26, 28, 30, 32, 34, 38, 39 and 40 (or SEQ ID NOS: 26, 28, 30, 32, 34 and 38); and / or (b) a Vl sequence identical to a Vl sequence reference selected from the group having amino acid sequences represented by SEQ ID NOS: 27, 29, 31, 33, 35, 37 and 41 (or SEQ ID NOS: 27, 29, 31, 35 and 37).

[00296] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: the Vh sequence as set forth in SEQ ID NO: 26, and / or a Vl sequence as set forth in SEQ ID NO: 27.

[00297] In certain embodiments, anti-CD123 / IL-3Ro antibodies and their antigen-binding fragments comprise: the Vh sequence as set forth in SEQ ID NO: 28, and / or a Vl sequence as set forth in SEQ ID NO: 29.

[00298] In certain embodiments, anti-CD123 / IL-3Ro antibodies and their antigen-binding fragments comprise: the Vh sequence as set forth in SEQ ID NO: 30, and / or a Vl sequence as set forth in SEQ ID NO: 31.

[00299] In certain embodiments, anti-CD123 / IL-3Ro antibodies and their antigen-binding fragments comprise: the Vh sequence as set forth in SEQ ID NO: 34, and / or a Vl sequence as set forth in SEQ ID NO: 35.

[00300] In certain embodiments, anti-CD123 / IL-3Ro antibodies and their antigen-binding fragments comprise a Petition 870260060475, dated 06 / 19 / 2026, pp. 154 / 752 149 / 355 sequence Vh and a sequence Vl with a combination of SEQ ID Nos. selected from the group consisting of: 32 / 33, 34 / 33, 38 / 33, 39 / 33, 40 / 33, 32 / 35, 34 / 35, 38 / 35, 39 / 35, 40 / 35, 32 / 37 34 / 37, 38 / 37, 39 / 37, 40 / 37, 39 / 33, 39 / 35, 39 / 37, 39 / 41, 40 / 33, 40 / 35, 40 / 37 and 40 / 41.

[00301] For example, in one embodiment, the antiCD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 39 or 40; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41. In certain embodiments, the Vh sequence is shown in SEQ ID NO: 39, and the Vl sequence is shown in SEQ ID NO: 41. In certain embodiments, the Vh sequence is shown in SEQ ID NO: 40 and the Vl sequence is shown in SEQ ID NO: 41.

[00302] In one reported embodiment, the anti-CD123 / IL3Ra antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 34; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 35. In certain embodiments, Xaa in SEQ ID NO: 34 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 34 is Val (V).

[00303] In another embodiment, the anti-CD123 / IL-3Rα antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 39 or 40, except that the first residue is replaced by Ser (S); and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41.

[00304] In another embodiment, anti-CD123 / IL-3Rα antibodies Petition 870260060475, dated 06 / 19 / 2026, pp. 155 / 752 150 / 355 and its antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 39 or 40; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41, except that the first residue is replaced by Ser (S).

[00305] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 59 or 60, except that the N-terminal residue is Ser, and except that the residue corresponding to the 5th to last residue of SEQ ID NO: 54 is Cys; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41.

[00306] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 59 or 60, except that the residue corresponding to the 5th to last residue of SEQ ID NO: 54 is Cys; and b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 41, except that the N-terminal residue is Ser.

[00307] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 38; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 35. In certain embodiments, Xaa in SEQ ID NO: 38 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 38 is Val (V). Petition 870260060475, dated 06 / 19 / 2026, pp. 156 / 752 151 / 355

[00308] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) a variable immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 34; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 37. In certain embodiments, Xaa in SEQ ID NO: 34 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 34 is Val (V).

[00309] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 56; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 35. In certain embodiments, Xaa in SEQ ID NO: 56 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 56 is Val (V).

[00310] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 54; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 37. In certain embodiments, Xaa in SEQ ID NO: 54 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 54 is Val (V).

[00311] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 59 or 60, except that the residue corresponding to the 5th to last residue of SEQ ID NO: 54 is Cys; and b) a variable immunoglobulin light chain region. Petition 870260060475, dated 06 / 19 / 2026, pp. 157 / 752 152 / 355 possessing the amino acid sequence presented in SEQ ID NO: 41.

[00312] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region possessing the amino acid sequence presented in SEQ ID NO: 54; and, b) an immunoglobulin light chain variable region possessing the amino acid sequence presented in SEQ ID NO: 35. In certain embodiments, Xaa in SEQ ID NO: 54 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 54 is Val (V).

[00313] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 56; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 35. In certain embodiments, Xaa in SEQ ID NO: 56 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 56 is Val (V).

[00314] In another embodiment, the anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments comprise: a) an immunoglobulin heavy chain region having the amino acid sequence shown in SEQ ID NO: 54; and, b) a variable immunoglobulin light chain region having the amino acid sequence shown in SEQ ID NO: 37. In certain embodiments, Xaa in SEQ ID NO: 54 is Phe (F). In certain embodiments, Xaa in SEQ ID NO: 54 is Val (V).

[00315] In certain embodiments, anti-CD123 / IL-3Ra antibodies and their antigen-binding fragments bind specifically to CD123 / IL-3Ra. In certain embodiments, the CD123 / IL-3Ra antibody or its antigen-binding fragment is a murine, chimeric, humanized, or human antibody or its fragment. Petition 870260060475, dated 06 / 19 / 2026, pp. 158 / 752 153 / 355 antigen-binding fragment that specifically binds to CD123 / IL-3Ra. In certain embodiments, the humanized antibody or its antigen-binding fragment is an antigen-binding or CDR-inhibited antibody or fragment thereof.

[00316] In certain embodiments, anti-CD123 / IL-3Ra antibodies are full-length antibodies. Full-length antibodies may comprise any of the antibodies defined above by CDR 1-4 (e.g., CDR1 and CDR2 heavy chain; CDR1 and CDR2 heavy and light chains), 1-6 CDR sequences (e.g., CDR1-CDR3 heavy chain; CDR1-CDR3 heavy and light chains) or any of the antibodies defined above by LCVR and / or HCVR, or any of the full-length antibodies having a heavy chain sequence in Table 5, or any of the full-length antibodies having a light chain sequence in Table 6, or any of the full-length antibodies having a heavy chain sequence in Table 5 and a light chain sequence in Table 6. Table 5 Full-Length Heavy Chain Amino Acid Sequences Complete Sequence of Heavy Chain Amino Acids Antibody (SEQ ID NO) CD123-3 EFQLQQSGPEVVKPGASVKMSCKASGYTFTSYVMHWMKQK PGQGLEWIGYIKPYKDGTKYNEKFKGKATLISDKPSSTAYME LSSLTSEDSAVYYCAREGENGYYDAMDYWGQGTSVTVSSA KTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWN SGSLSSGVHTFPAVLESDLYTLSSSVTVPSSPRPSETVTCNV AHPASSTKVDKKIVPRDCGCKPCICTVPEVSSVFIFPPKPKDV LTITLTPKVTCVVVDISKDDPEVQFSWFVDDVEVHTAQTQPR EEQFNSTFRSVSELPIMHQDWLNGKEFKCRVNSAAFPAPIEK TISKTKGRPKAPQVYTIPPPKEQMAKDKVSLTCMITDFFPEDI TVEWQWNGQPAENYKNTQPIMNTNGSYFVYSKLNVQKSNW Petition 870260060475, dated 06 / 19 / 2026, page 159 / 752 154 / 355 EAGNTFTCSVLHEGLHNHHTEKSLSHSPGK (SEQ ID NO:42) CD123-6 EFQLQQSGPELVKPGASVKMSCKASGYIFTSSIMHWMKQKP GQGLEWIGYIKPYNDGTKYNEKFKGKATLTSDKSSSTANMEL NSLTSEDSAVYCAREGGNDYYDTMDYWGQGTSVTVSSAK TTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPPVTWNS GSLSSSGVHTFPAVLESDLYTLSSSVTVPSSMRPSETVTCNVA HPASSTKVDKKIVPRDCGCKPCICTVPEVSSVFIFPPKPKDVL TITLTPKVTCVVVDISKDDPEVQFSWFVDDVEVHTAQTQPRE EQFNSTFRSVSELPIMHQDWLNGKEFKCRVNSAAFPAPIEKT ISKTKGRPKAPQVYTIPPKEQMAKDKVSLTCMITDFFPEDIT VEWQWNGQPAENYKNTQPIMNTNGSYFVYSKLNVQKSNWE AGNTFTCSVLHEGLHNHHTEKSLSHSPGK (SEQ ID NO:44) CD123- EVKLVESGGDLVKPGGSLKLSCAASGFTFSNYAMSWVRQN 14 SEKRLEWVATINSGGSFTYYPDSVKGRFTISRDNAKDSLYLQ MSSLNSEDTAMYYCARQSEAYYGYDKRTWFAYWGQGTLVT VSSAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVT VTWNSGSLSSGVHTFPAVLESDLYTLSSSVTVPSSPRPSETV TCNVAHPASSTKVDKKIVPRDCGCCKPCICTVPEVSSVFIFPPK PKDVLTITLTPKVTCVVVDISKDDPEVQFSWFVDDVEVHTAQ TQPREEQFNSTFRSVSELPIMHQDWLNGKEFKCRVNSAAFP APIEKTISKTKGRPKAPQVYTIPPPKEQMAKDKVSLTCMITDF FPEDITVEWQWNGQPAENYKNTQPIMNTNGSYFVYSKLNVQ KSNWEAGNTFTCSVLHEGLHNHHTEKSLSHSPGK (SEQID NO:46) huCD123 QVQLVQSGAEVKKPGASVKVSCKASGYGFTSSIMHWVRQA -6Gv1 PGQGLEWMGYIKPYNDGTKYNEKFKGRVTMTRDTSTSTVY MELSSLRSEDTAVYCAREGGNDYYDTMDYWGQGTLVTVS SASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTPAVLQSSGLYSLSSVVPSSSLGTQTYI CNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSV FLFPPKPKDTLMISRTPEVTVCVVDVSHEDPEVKFNWYVDGV EVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKV SNKALPAPIEKTISKAGGQPREPQVYTLPPSRDELTKNQVSLT Petition 870260060475, de 19 / 06 / 2026, pág. 160 / 752 155 / 355 CLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLY SKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:48) huCD123 -6Gv6 / 7 QXQLVQSGAEVKKPGASVKVSCKASGYIFTSSIMHWVRQAP GQGLEWIGYIKPYNDGTKYNEKFKGRATLTSDRSTSTAYMEL SSLRSEDTAVYYCAREGGNDYYDTMDYWGQGTLVTVSSAS TKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNS GALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNV NHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLF PPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEV HNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCL VKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKL TVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:50) huCD123 -6 Gv6 / 7NTS2(ou S2) SXQLVQSGAEVKKPGASVKVSCKASGYIFTSSIMHWVRQAP GQGLEWIGYIKPYNDGTKYNEKFKGRATLTSDRSTSTAYMEL SSLRSEDTAVYYCAREGGNDYYDTMDYWGQGTLVTVSSAS TKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNS GALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNV NHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLF PPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEV HNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKL TVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:53) huCD123 -6 Gv6 / 7CysMab QXQLVQSGAEVKKPGASVKVSCKASGYIFTSSIMHWVRQAP GQGLEWIGYIKPYNDGTKYNEKFKGRATLTSDRSTSTAYMEL SSLRSEDTAVYYCAREGGNDYYDTMDYWGQGTLVTVSSAS TKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNS GALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNV NHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLF Petition 870260060475, dated 06 / 19 / 2026, page 161 / 752 156 / 355 PPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEV HNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCL VKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKL TVDKSRWQQGNVFSCSVMHEALHNHYTQKSLCLSPG (SEQ ID NO:54) huCD123 -6 Gv6 / 7S2- CysMab SXQLVQSGAEVKKPGASVKVSCKASGYIFTSSIMHWVRQAP GQGLEWIGYIKPYNDGTKYNEKFKGRATLTSDRSTSTAYMEL SSLRSEDTAVYYCAREGGNDYYDTMDYWGQGTLVTVSSAS TKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNS GALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNV NHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLF PPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEV HNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCL VKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKL TVDKSRWQQGNVFSCSVMHEALHNHYTQKSLCLSPG (SEQ ID NO:56) huCD123 -6rhv1.0 QVQLVQSGAEVVKPGASVKMSCKASGYTFTSSIMHWMKQK PGQGLEWIGYIRPYNDGTRYNQKFQGKATLTSDRSSSTANM ELNSLTSEDSAVYYCAREGGNDYYDTMDYWGQGTSVTVSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSW NSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYIC NVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGV EVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKV SNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLT CLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLY SKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:59) huCD123 -6rhv1.1 QFQLVQSGAEVVKPGASVKMSCKASGYTFTSSIMHWMKQK PGQGLEWIGYIKPYNDGTKYNQKFQGKATLTSDKSSSTANM ELNSLTSEDSAVYYCAREGGNDYYDTMDYWGQGTSVTVSS. Petição 870260060475, de 19 / 06 / 2026, pág. 162 / 752 157 / 355 ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSW NSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYIC NVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGV EVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKV SNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLT CLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLY SKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:60) *In all the sequences above where the 2nd residue of the N-terminal is X (or Xaa), for example SEQ ID NOs: 50, 53, 54, and 56, X is F for Gv6 sequences, while X is V for Gv7 sequences. In some modalities, the Met (in bold) in SEQ ID NO: 44 is Pro. Table 6 Full-Length Light Chain Amino Acid Sequences Antibody Full-Length Light Chain Amino Acid Sequence (SEQ ID NO) CD123-3 DIQMTQSPSSLSASLGGKVTITCKASQDINKYIAWYQHK PGKGPRLLIHYTSTLQPGIPSRFSGSGSGRDYSFSISNL EPEDIATYYCLQYDNLLYTFGGGTKLELKRADAAPTVSI FPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSER QNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSY TCEATHKTSTSPIVKSFNRNEC (SEQ ID NO:43) CD123-6 DIKMTQSPSSMYASLGERVTITCKASQDINSYLSWFQQ KPGKSPKTLIYRVNRLVDGVPSRFSGSGSGQDYSLTIS SLEYEDMGIYYCLQYDAFPYTFGGGTKLEIKRADAAPT VSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGS ERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHN SYTCEATHKTSTSPIVKSFNRNEC (SEQ ID NO:45) CD123-14 DILLTQSPAILSVSPGTRVSFSCRASQSVGTSIHWYQQ RPNGFPRLLIKYASESISGIPSRFSGSGSGTDFTLNINSV Petition 870260060475, dated 06 / 19 / 2026, page 163 / 752 158 / 355 ESEDIADYYCQQSKSWPLTFGAGTKLELKRADAAPTVS IFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSE RQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNS YTCEATHKTSTSPIVKSFNRNEC (SEQ ID NO:47) huCD123- 6Gv1 DIQMTQSPSSLSASVGDRVTITCRASQDINSYLAWFQQ KPGKAPKSLIYRVNRLVSGVPSRFSGSGSGTDFTLTISS LQPEDFATYYCLQYDAFPYTFGQGTKVEIKRTVAAPSV FIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNA LQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKV YACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:49) huCD123- 6Gv4 DIQMTQSPSSLSASVGDRVTITCRASQDINSYLSWFQQ KPGKAPKTLIYRVNRLVDGVPSRFSGSGSGNDYTLTIS SLQPEDFATYYCLQYDAFPYTFGQGTKVEIKRTVAAPS VFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDN ALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHK VYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:51) huCD1236Gv4-NTS3 (ou S3) SIQMTQSPSSLSASVGDRVTITCRASQDINSYLSWFQQ KPGKAPKTLIYRVNRLVDGVPSRFSGSGSGNDYTLTIS SLQPEDFATYYCLQYDAFPYTFGQGTKVEIKRTVAAPS VFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDN ALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHK VYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:58) huCD123- 6rlv1.0 DIQMTQSPSSMSASVGERVTITCRASQDINSYLSWFQQ KPGKSPKTLIYRVNRLVDGVPSRFSGSGSGQDYSLTIS SLEPEDMGIYYCLQYDAFPYTFGQGTKLEIKRTVAAPS VFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDN ALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHK VYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:61).

[00317] In certain embodiments, anti-CD123 / IL3Ra antibodies are full-length antibodies comprising: (a) a heavy chain with at least about 90%, 95%, 96%, 97%, 98% or 99% sequence identity to any of the sequences Petition 870260060475, dated 06 / 19 / 2026, page 164 / 752 (a) a full-length heavy chain sequence 159 / 355 above, such as any of the full-length heavy chain sequences in Table 5; and / or (b) a light chain with at least about 90%, 95%, 96%, 97%, 98%, or 99% sequence identity to any of the full-length light chain sequences above, such as any of the full-length light chain sequences in Table 6.In certain embodiments, anti-CD123 / IL-3Ra antibodies are full-length antibodies comprising a full-length heavy chain sequence and a full-length light chain sequence combination selected from the group consisting of SEQ ID NOs: 42 / 43, 44 / 45, 46 / 47, 48 / 49, 50 / 49, 53 / 49, 54 / 49, 56 / 49, 59 / 49, 60 / 49, 48 / 51, 50 / 51, 53 / 51, 54 / 51, 56 / 51, 59 / 51, 60 / 51, 48 / 58, 50 / 58, 53 / 58, 54 / 58, 56 / 58, 59 / 58, 60 / 58, 59 / 49, 59 / 51, 59 / 58. 59 / 61, 60 / 49, 60 / 51, 60 / 58 and 60 / 61, or antibodies with at least about 90%, 95%, 96%, 97%, 98% or 99% sequence identity for any of the full-length heavy chain sequences and / or their light chain sequences.

[00318] In certain embodiments, anti-CD123 / IL3Ra antibodies are full-length antibodies comprising a full-length heavy chain sequence and a complete light chain sequence combination selected from the group consisting of SEQ ID NOs: 59 / 61 and 60 / 61, or antibodies with at least about 90%, 95%, 96%, 97%, 98% or 99% sequence identity for any of the full-length heavy chain sequences and / or their light chain sequences. Such antibodies may further comprise engineered N-terminal Ser / Thr in the light chain, heavy chain or both. Such antibodies may further comprise modified Cys in the CH3 domain of the heavy chain at a position corresponding to the 5th to last Cys of SEQ ID NO: 54.

[00319] In certain embodiments, the anti-CD123 / IL3Ra antibody Petition 870260060475, dated 06 / 19 / 2026, p. 165 / 752 160 / 355 3Ra is a murine, chimeric, humanized, or human antibody that specifically binds to CD123 / IL-3Ra. In certain embodiments, the anti-CD123 / IL-3Ra antibody possessing a certain percentage of sequence identity for any of the full-length SEQ ID NOs differs from such SEQ ID NOs only by conservative amino acid substitutions, for example, only by 1, 2, 3, 4, or 5 consecutive conservative amino acid substitutions. In certain embodiments, the conservative amino acid substitutions are outside the CDRs.

[00320] In certain embodiments, its antigen-binding fragment is or comprises a single-chain Fab, Fd, Fab', F (ab')2, Fv or scFv, disulfide-linked Fv, V-NAR domain, IgNar, intracorpora, IgGΔCH2, minibody, F (ab')3, tetrabody, triabody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb2, (scFv)2, or scFv-Fc, of any of the above antibodies.

[00321] In a related aspect, the invention also provides a polypeptide comprising any of the antibodies or their antigen-binding fragments, any of the Vh and / or Vl sequences above, any of the HCVR and / or LCVR sequences above, or any of the HCVR and / or LCVR sequences (CDRs) above. The polypeptide may, for example, fuse with a non-antibody protein or domain. In certain embodiments, the fusion protein is not a fusion with a Pseudomonas toxin.

[00322] The affinity or avidity of antibodies for an antigen can be determined experimentally using any suitable method known in the art, for example, flow cytometry, enzyme-linked immunosorbent assay (ELISA), or radioimmunoassay (RIA) or kinetics (e.g., BIACORE™ analysis). Direct binding assays as well as competitive binding assay formats can be readily employed. See, for example, Berzofsky et al. Petition 870260060475, dated 06 / 19 / 2026, p. 166 / 752 161 / 355 et al., Antibody-Antigen Interactions, in Fundamental Immunology, Paul, WE, Ed., Raven Press: New York, NY (1984); Kuby, Janis Immunology, WH Freeman and Company: New York, NY (1992); and the methods described herein.

[00323] The measured affinity of a specific antibody-antigen interaction may vary if measured under different conditions (e.g., salt concentration, pH, temperature). Thus, affinity measurements and other antigen-binding parameters (e.g., KD or Kd, kon, koff) are made with standardized antibody-antigen solutions and a standardized buffer, as is known in the art and as the buffer described herein.

[00324] In one aspect, linkage assays can be performed using flow cytometry on cells expressing the CD123 / IL-3Ra antigen on the surface. For example, CD123 / IL-3Ro positive cells can be incubated with varying concentrations of anti-CD123 / IL-3Ra antibodies using 1 χ¹⁰⁵ cells per sample in 100 μL of FACS buffer (e.g., RPMI-1640 medium supplemented with 2% normal goat serum). The cells can then be pelleted, washed, and incubated for 1 h with 100 μL of FITC-conjugated anti-mouse-goat IgG antibody or anti-human (goat) IgG antibody (being obtained from, for example, Jackson Laboratory, 6 μg / mL in FACS buffer). The cells could be pelleted again, washed with FACS buffer, and then resuspended in 200 µL of PBS containing 1% formaldehyde.Samples can be obtained, for example, using a FACSCalibur flow cytometer with the HTS multi-well sampler and analyzed using CellQuest Pro (all from BD Biosciences, San Diego, USA). For each sample, the mean fluorescence intensity for FL1 (IFM) can be exported and plotted against antibody concentration on a semi-log graph to generate a binding curve. Petition 870260060475, dated 06 / 19 / 2026, page 167 / 752 A 162 / 355 sigmoidal dose-response curve is suitable for binding curves, and EC50 values ​​are calculated using programs such as GraphPad Prism v4 with standard parameters (GraphPad software, San Diego, CA). EC50 values ​​can be used as a measure of the apparent dissociation constant Kd or KD for each antibody.

[00325] Monoclonal antibodies can be prepared using hybridoma methods, such as those described by Kohler and Milstein (1975) Nature 256:495. When using the hybridoma method, a mouse, hamster, or other suitable host animal is immunized to elicit the production of antibody lymphocytes that will specifically bind to an immunizing antigen. Lymphocytes can also be immunized in vitro. After immunization, the lymphocytes are isolated and fused with an appropriate myeloma cell line using, for example, polyethylene glycol, to form hybridoma cells that can subsequently be selected from non-myeloma lymphocytes.Hybridomas that produce monoclonal antibodies specifically directed against a chosen antigen, as determined by immunoprecipitation, immunotransfer, or by an in vitro binding assay (e.g., radioimmunoassay (RIA); enzyme-linked immunosorbent assay (ELISA)), can then be propagated either in vitro using standard methods (Goding, Monoclonal Antibodies: Principles and Practice, Academic Press, 1986) or in vivo as ascitic tumors in an animal. The monoclonal antibodies can then be purified from culture medium or ascitic fluid, as described for polyclonal antibodies.

[00326] Alternatively, monoclonal antibodies can also be made using recombinant DNA methods, as described in US Patent 4,816,567. The polynucleotides encoding a monoclonal antibody are isolated from mature B cells or cells Petition 870260060475, dated 06 / 19 / 2026, page 168 / 752 163 / 355 of the hybridoma, such as by RT-PCR using oligonucleotide triggers that specifically amplify the genes encoding light and heavy chains of the antibody, and their sequence is determined using conventional procedures. The isolated polynucleotides encoding the light and heavy chains are then cloned into suitable expression vectors, which, when transfected into host cells, such as E. coli cells, simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, monoclonal antibodies are generated by host cells. Furthermore, recombinant monoclonal antibodies or respective fragments of the desired species can be isolated from phage display libraries expressing CDRs of the desired species, as described (McCafferty et al., Nature 348:552-554, 1990; Clackson et al., Nature, 352:624-628, 1991; and Marks et al., J. Mol. Biol.222:581-597, 1991).

[00327] The polynucleotide(s) encoding a monoclonal antibody can be further modified in numerous different ways using recombinant DNA technology to generate alternative antibodies. In some embodiments, the constant domains of the light and heavy chains, for example, a mouse monoclonal antibody, can be replaced 1) by these regions from, for example, a human antibody to generate a chimeric antibody or 2) from a non-immunoglobulin polypeptide to generate a fusion antibody. In some embodiments, the constant regions are truncated or removed to generate the desired antibody fragment from a monoclonal antibody. Site-directed or high-density mutagenesis of the variable region can be used to optimize the specificity, affinity, etc. of a monoclonal antibody.

[00328] In some forms, the monoclonal antibody against the Petition 870260060475, dated 06 / 19 / 2026, page 169 / 752 164 / 355 Human CD123 / IL-3Ra is a humanized antibody. In certain embodiments, these antibodies are therapeutically used to reduce antigenicity and HAMA (human anti-mouse antibody) responses when administered to a human subject.

[00329] Methods for human or non-human engineered, humanizing, or resurgent antibodies may also be used and are well known in the art. A humanized, resurgent, or similarly engineered antibody may have one or more amino acid residues from a non-human source, for example, but not limited to, mouse, rat, rabbit, non-human primates, or other mammals. These non-human amino acid residues are replaced by residues that are often referred to as import residues, which are typically taken from an import variable, constant, or other domain of a known human sequence.

[00330] These imported sequences can be used to reduce immunogenicity or to reduce, increase, or modify binding, affinity, rate, off-rate, avidity, specificity, half-life, or any other appropriate characteristic known in the art. In general, CDR residues are directly and substantially involved in influencing CD123 / IL-3Ra binding. Therefore, some or all human or non-human CDR sequences are retained, while non-human sequences of the variable and constant regions can be replaced by human amino acids or other amino acids.

[00331] Antibodies may also optionally be humanized, resurgent, engineered antibodies, or engineered human antibodies with high-affinity retention for CD123 / IL3Rα antigen and other favorable biological properties. To achieve this goal, humanized anti-CD123 / IL-3Rα antibodies (or Petition 870260060475, dated 06 / 19 / 2026, p. 170 / 752 165 / 355 human) or manipulated and resurgent antibodies can optionally be prepared by a process of analyzing parental sequences and various conceptual humanized and manipulated products using three-dimensional models of parental, manipulated, and humanized sequences. Three-dimensional immunoglobulin models are commonly available and familiar to those skilled in the art. Computer programs are available which illustrate and display probable three-dimensional conformational structures of immunoglobulin sequences from the selected candidate. Inspection of these displays allows analysis of the probable role of residues in the functioning of the candidate immunoglobulin sequence, i.e., analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen, such as CD123 / IL-3Ra.In this way, framework residues (FR) can be selected and combined from consensus and import sequences, so that the desired antibody characteristic, such as higher affinity for target antigens, is achieved.

[00332] The humanization, resurfacing, or antibody engineering of the present invention can be performed using any known method, such as, but not limited to, those described in Winter (Jones et al., Nature 321: 522, 1986; Riechmann et al., Nature 332: 323, 1988; Verhoeyen et al., Science 239: 1534, 1988; Sims et al., J. Immunol. 151:2296, 1993; Chothia and Lesk, J. Mol. Biol. 196:901, 1987; Carter et al., Proc. Natl. Acad. Sci. USA 89:4285, 1992; Presta et al., J. Immunol. 151:2623, 1993; Raguska et al., Proc. Natl. Academic. Sci. USA 91(3):969-973, 1994; US Pat. Us. 5,639,641, 5,723,323; 5,976,862; 5,824,514; 5,817,483; 5,814,476; 5,763,192; 5,723,323; 5,766,886; 5,714,352; 6,204,023; 6,180,370; 5,693,762; 5,530,101; 5,585,089; 5,225,539; 4,816,567; PCT / : US98 / 16280; US96 / 18978; US91 / 09630; US91 / 05939; US94 / 01234; Petition 870260060475, dated 06 / 19 / 2026, p. 171 / 752 166 / 355 GB89 / 01334; GB91 / 01134; GB92 / 01755; WO90 / 14443; WO90 / 14424; WO90 / 14430; EP 229246; 7,557,189; 7,538,195; and 7,342,110, each of which is incorporated herein by reference, including the references cited.

[00333] In certain alternative embodiments, the antibody to CD123 / IL-3Ra is a human antibody. Human antibodies can be prepared directly using various techniques known in the art. Immortalized human B lymphocytes that have been immunized in vitro or isolated from an immunized individual producing an antibody directed against a target antigen can be generated (see, for example, Cole et al., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77 (1985); Boemer et al., 1991, J. Immunol, 147 (1):86-95; and US Patent 5,750,373). Furthermore, the human antibody can be selected from a phage library, wherein that phage library manifests human antibodies described, for example, in Vaughan et al., Nat. Biotech. 14:309-314, 1996, Sheets et al., Proc. Nat'l. Academic. Sci. 95:6157-6162, 1998, Hoogenboom and Winter, J. Mol. Biol. 227:381,1991, and Marks et al., J. Mol. Biol. 222:581, 1991).Techniques for generating and using antibody phage libraries are also described in U.S. Patents Nos. 5,969,108, 6,172,197, 5,885,793, and 6,521,404. 6,544,731; 6,555,313; 6,582,915; 6,593,081; 6,300,064; 6,653,068; 6,706,484; and 7,264,963; and Rothe et al., J. Mol. Bio. doi: 10.1016 / j.jmb.2007.12.018, 2007 (each of which is incorporated by reference in its entirety). Affinity maturation strategies and chain scrambling strategies (Marks et al., Bio / Technology 10:779-783, 1992, incorporated by reference in its entirety) are known in the art and can be employed to generate high-affinity human antibodies.

[00334] Humanized antibodies can also be made in transgenic mice containing human immunoglobulin loci. Petition 870260060475, dated 06 / 19 / 2026, page 172 / 752 167 / 355 which are capable, through immunization, of producing the complete repertoire of human antibodies in the absence of endogenous immunoglobulin production. This approach is described in U.S. Patents Nos. 5,545,807; 5,545,806; 5,569,825; 5,625,126; 5,633,425; and 5,661,016.

[00335] In certain embodiments, an antibody fragment is provided to, for example, increase tumor penetration. Several techniques are known for the production of antibody fragments. Traditionally, these fragments are derived by proteolytic digestion of intact antibodies (e.g., Morimoto et al., Journal of Biochemical and Biophysical Methods 24: 107-117, 1993; Brennan et al., Science 229:81, 1985). In certain embodiments, antibody fragments are produced recombinantly. Fab, Fv, and scFv antibody fragments can all be expressed and secreted from E. coli or other host cells, thus allowing the production of large quantities of these fragments. These antibody fragments can also be isolated from antibody phage libraries. The antibody fragment can also be linear antibodies described in US Patent No. 5,641,870, for example, and can be mono- or bispecific.Other techniques for producing antibody fragments will become apparent to those skilled in the art.

[00336] For the purposes of the present invention, it should be appreciated that the modified antibodies may comprise any type of variable region that provides for the association of the antibody with the polypeptides of a human CD123 / IL-3Ra. In this respect, the variable region may comprise or be derived from any type of mammal that can be induced to mount a humoral response and generate immunoglobulins against the desired associated tumor antigen. Thus, the variable region of the modified antibodies may be, for example, human, murine, Petition 870260060475, dated 06 / 19 / 2026, page 173 / 752 168 / 355 non-human primates (e.g., cynomolgus monkeys, macaques, etc.) or of lupine origin. In some embodiments, the variable and constant regions of the modified immunoglobulins are human. In other embodiments, the variable regions of compatible antibodies (generally derived from a non-human source) may be specifically designed or adapted to improve the binding properties or reduce the immunogenicity of the molecule. In this respect, the variable regions useful in the present invention may be humanized or altered by the inclusion of imported amino acid sequences.

[00337] In certain embodiments, the variable domains in the light and heavy chains are altered by at least partial substitution of one or more CDRs and, if necessary, by partial substitution of the framework region and sequence alteration.Although CDRs can be derived from an antibody of the same class or even subclass as the antibody from which the structural regions are derived, it is nevertheless anticipated that CDRs will be derived from an antibody of a different class and, in certain embodiments, from an antibody of a different species. It may not be necessary to replace all CDRs with complete donor variable region CDRs to transfer antigen-binding capability from one variable domain to another. Conversely, it may only be necessary to transfer those residues that are needed to maintain the activity of the antigen-binding site. Given the explanations set forth in U.S. Patent Nos. 5,585,089, 5,693,761, and 5,693,762, it will be well within the competence of those skilled in the art, through routine experimentation or trial and error, to obtain a functional antibody with reduced immunogenicity.

[00338] Changes in the variable region, notwithstanding, those skilled in the art will appreciate that the modified antibodies of this invention comprise antibodies (for example, antibodies Petition 870260060475, dated 06 / 19 / 2026, page 174 / 752 169 / 355 complete or their immunoreactive fragments) in which at least a portion of one or more domains of the constant region has been eliminated or altered in order to provide desired biochemical characteristics such as increased tumor localization or reduced serum half-life when compared with an antibody of approximately the same immunogenicity comprising a native or unaltered region. In some embodiments, the constant region of the modified antibodies will comprise a human constant region. Modifications of the constant region compatible with this invention comprise additions, deletions, or substitutions of one or more amino acids in one or more domains. That is, the modified antibodies disclosed in this document may include alterations or modifications in the three constant domains of a heavy chain (CH1, CH2, or CH3) and / or in the constant domain of the light chain (CL).In some embodiments, modified constant regions are contemplated in which one or more domains are partially or totally eliminated. In some embodiments, the compatible modified antibodies will comprise deleted domain constructs or variants, in which the entire CH2 domain has been removed (ACH2 constructs). In some embodiments, the omitted constant region domain will be replaced by a short amino acid spacer (e.g., 10 residues) that provides the molecular flexibility normally conveyed by the absent constant region.

[00339] It will be observed that in certain embodiments, the modified antibodies can be designed to fuse the CH3 domain directly to the hinge region of the respective modified antibodies. It may be desirable to provide a peptide spacer between the hinge region and the modified CH2 and / or CH3 domains. For example, compatible constructs could be expressed in which the CH2 domain has been deleted and the remaining CH3 domain (modified or not) Petition 870260060475, dated 06 / 19 / 2026, pp. 175 / 752 The modified 170 / 355 antibody is joined to the hinge region with a 5-20 amino acid spacer. This spacer may be added, for example, to ensure that the regulatory elements of the constant domain remain free and accessible or that the hinge region remains flexible. However, it is observed that amino acid spacers may, in some cases, prove to be immunogenic and elicit an unwanted immune response against the construct. In this sense, in certain embodiments, any spacer added to the construct will be relatively non-immunogenic, or even omitted completely, in order to maintain the desired biochemical qualities of the modified antibodies.

[00340] In addition to the exclusion of all domains from the constant region, it will be appreciated that the antibodies of the present invention may be provided by the partial exclusion or substitution of some or even a single amino acid. For example, the mutation of a single amino acid in selected areas of the CH2 domain may be sufficient to substantially reduce Fc binding and thus increase tumor localization. Similarly, it may be desirable to simply exclude that part of one or more domains of the constant region that control the effector function (e.g., complementary C1Q binding) to be modulated. These partial exclusions of constant regions may improve selected antibody characteristics (serum half-life) while leaving other desirable functions associated with the constant region domain intact in the subject.Furthermore, as mentioned above, the constant regions of the disclosed antibodies can be modified, for example, through mutation or substitution of one or more amino acids, which can enhance the profile of the resulting construct. In this regard, it may be possible to disrupt the activity provided by a conserved binding site (e.g., Fc binding) while substantially maintaining the configuration and profile. Petition 870260060475, dated 06 / 19 / 2026, page 176 / 752 171 / 355 immunogenic modified antibody. Certain embodiments may involve the addition of one or more amino acids to the constant region to enhance desirable characteristics, such as increasing or decreasing effector function or providing more carbohydrate or cytotoxin attachment. In such embodiments, it may be desirable to insert or replicate specific sequences derived from selected constant region domains.

[00341] The present invention further encompasses variants and equivalents that are substantially homologous to the chimeric, humanized, and human antibodies or antibody fragments thereof set forth herein. They may contain, for example, conservative substitution mutations, i.e., substitution of one or more amino acids by similar amino acids. For example, conservative substitution refers to the substitution of one amino acid for another within the same general class, such as, for example, an acidic amino acid for another acidic amino acid, a basic amino acid for another basic amino acid, or a neutral amino acid for another neutral amino acid. What is intended by a conservative amino acid substitution is well known in the art, as defined above.

[00342] The polypeptides of the present invention may be recombinant polypeptides, natural polypeptides, or synthetic polypeptides, comprising an antibody or fragment thereof, against a human CD123 / IL-3Ra. It will be recognized in the art that some amino acid sequences of the invention may be altered without significant effect on the structure or function of the protein. Thus, the invention further includes variations of the polypeptides that show substantial activity or that include regions of an antibody, or fragment thereof, against a CD123 antigen, such as a human CD123. These mutants include deletions, insertions, inversions, repeats, and substitutions of the same type. Petition 870260060475, dated 06 / 19 / 2026, page 177 / 752 172 / 355

[00343] Polypeptides and analogues can be further modified to contain additional chemical moieties that are not normally part of the protein. These derived moieties can improve the solubility, biological half-life, or absorption of the protein. The moieties can also reduce or eliminate any undesirable side effects of proteins and similar substances. An overview of these moieties can be found in REMINGTON'S PHARMACEUTICAL SCIENCES, 20th ed., Mack Publishing Co., Easton, PA (2000).

[00344] The isolated polypeptides described herein can be produced by any suitable method known in the art. These methods range from direct protein synthesis methods to the construction of a DNA sequence encoding isolated polypeptide sequences and expressing those sequences in a suitable, transformed host. In some embodiments, a DNA sequence is constructed using recombinant technology by isolating or synthesizing a DNA sequence encoding a wild-type protein of interest. Optionally, the sequence can be mutagenized by site-specific mutagenesis to provide functional analogs. See, for example, Zoeller et al., Proc. Nat'l. Acad. Sci. USA 81:5662-5066, 1984, and US Pat. No. 4,588,585.

[00345] In some embodiments, a DNA sequence encoding a polypeptide of interest (e.g., antibody, antigen-binding fragment, or polypeptide of the invention) would be constructed wholly or partially by chemical synthesis using an oligonucleotide synthesizer. These oligonucleotides can be designed based on the amino acid sequence of the desired polypeptide and by selecting those codons that are favored in the host cell in which the recombinant polypeptide of interest will be produced. Standard methods can be applied to synthesize an isolated polynucleotide sequence encoding a polypeptide of Petition 870260060475, dated 06 / 19 / 2026, page 178 / 752 173 / 355 isolated interest. For example, a complete amino acid sequence can be used to construct a back-translated gene. Additionally, a DNA oligomer containing a nucleotide sequence encoding the specific isolated polypeptide can be synthesized. For example, several small oligonucleotides encoding portions of the desired polypeptide can be synthesized and then linked. The individual oligonucleotides typically contain 5' or 3' overhangs for complementary assembly.

[00346] Once assembled (by synthesis, site-directed mutagenesis, or other method), the polynucleotide sequences encoding a particular isolated polypeptide of interest will be inserted into an expression vector and operatively linked to the appropriate expression control sequence for protein expression in a desired host. Proper assembly can be confirmed by nucleotide sequencing, restriction mapping, and expression of a biologically active polypeptide in a suitable host. As is well known in the art, in order to obtain high expression levels of a transfected gene in a host, the gene must be operatively linked to transcriptional and translational expression control sequences that are functional in the chosen expression host.

[00347] In certain embodiments, recombinant expression vectors are used to amplify and express DNA-encoding antibodies or fragments thereof against human CD123 / IL3Ra. Recombinant expression vectors are replicable DNA constructs that have synthetic or cDNA-derived fragments of DNA encoding a polypeptide chain of an anti-CD123 / IL-3Ra antibody, or a fragment thereof, operatively linked to transcriptional or translational regulatory elements derived from mammalian, microbial, viral, or insect genes. A unit Petition 870260060475, dated 06 / 19 / 2026, page 179 / 752 Transcriptional 174 / 355 generally comprises a set of (1) a genetic element or elements having a regulatory role in gene expression, for example, transcriptional promoters or enhancers, (2) a structural or coding sequence that is transcribed into mRNA and translated into protein, and (3) appropriate transcription initiation and translation and termination sequences. These regulatory elements may include an operator sequence to control transcription. The ability to replicate in a host, usually conferred by an origin of replication, and gene selection to facilitate recognition of transformants may additionally be incorporated. DNA regions are operatively linked when they are functionally related to one another.For example, DNA for a signal peptide (secretory leader) is operatively linked to DNA for a polypeptide if it is expressed as a precursor that participates in the secretion of the polypeptide; a promoter is operatively linked to a coding sequence if it controls the transcription of the sequence; or a ribosome binding site is operatively linked to the coding sequence if it is positioned to allow translation. Structural elements intended for use in yeast expression systems include a leader sequence allowing extracellular secretion of the translated protein by a host cell. Alternatively, if the recombinant protein is expressed without a leader or transport sequence, it may include an N-terminal methionine residue. This residue may optionally be cleaved further from the expressed recombinant protein to provide an end product.

[00348] The choice of expression control sequence and expression vector will depend on the choice of host. A wide variety of host / expression vector combinations can be employed. Useful expression vectors for eukaryotic hosts, Petition 870260060475, dated 06 / 19 / 2026, page 180 / 752 175 / 355 include, for example, vectors comprising expression control sequences of SV40, bovine papillomavirus, adenovirus, and cytomegalovirus. Useful expression vectors for bacterial hosts include known bacterial plasmids, such as Escherichia coli plasmids, including pCR1, pBR322, pMB9 and their derivatives, more host-variant plasmids such as M13, and single-stranded DNA phages.

[00349] Suitable host cells for the expression of a CD123 / IL-3Ra binding polypeptide or antibody (or a CD123 / IL-3Ra protein to be used as an antigen) include prokaryotes, yeast, insect, or higher eukaryotic cells under the control of appropriate promoters. Prokaryotes include Gram-negative or Gram-positive organisms, for example, E. coli or bacilli. Higher eukaryotic cells include established cell lines originating from mammals, such as CHO cells. Cell-free translation systems may also be employed. Suitable expression and cloning vectors for use with bacterial, fungal, yeast, and mammalian cell hosts are described by Pouwels et al. (Cloning Vectors: A Laboratory Manual, Elsevier, NY, 1985), the relevant description of which is incorporated herein by reference.Additional information on methods of protein production, including antibody production, can be found, for example, in U.S. Patent Publication No. 2008 / 0187954, U.S. Patents Nos. 6,413,746 and 6,660,501, and International Patent Publication No. WO 04009823, each of which is incorporated herein by reference in its entirety.

[00350] Several mammalian or insect cell culture systems can also be advantageously employed to express the recombinant protein. The expression of recombinant proteins in mammalian cells can be performed because Petition 870260060475, dated 06 / 19 / 2026, page 181 / 752 176 / 355 These proteins are generally correctly folded, appropriately modified, and fully functional. Examples of suitable mammalian host cell lines include HEK-293 and HEK-293T, COS-7 monkey kidney cell lines, described by Gluzman (Cell 23:175, 1981), and other cell lines including, for example, L cells, CI 27, 3T3, Chinese hamster ovary (CHO) cell lines, HeLa, and BHK. Mammalian expression vectors may comprise non-transcribed elements such as an origin of replication, a suitable promoter and enhancer linked to the gene to be expressed, and other flanking 5' or 3' non-transcribed sequences and 5' or 3' untranslated sequences such as ribosome-required binding sites, a polyadenylation site, splice donor and acceptor sites, and transcription termination sequences.Baculovirus systems for the production of heterologous proteins in insect cells are analyzed by Luckow and Summers, Bio / Technology 6:47 (1988).

[00351] Thus, one aspect of the invention also provides a cell that produces any of the antibodies in question or their antigen-binding fragment, or any of the subject polypeptides. In certain embodiments, the cell is a mammalian cell. In certain embodiments, the cell is a HEK293 or HEK-293T cell, a COS-7 cell, an L cell, a CI 27 cell, a 3T3 cell, a Chinese hamster ovary (CHO) cell, a HeLa cell, or a BHK cell. In certain embodiments, the cell is a CHO cell.

[00352] Proteins produced by a transformed host can be purified according to any suitable method. Such standard methods include chromatography (e.g., ion exchange and affinity and sizing column chromatography), centrifugation, differential solubility, or any other technique. Petition 870260060475, dated 06 / 19 / 2026, page 182 / 752 177 / 355 standard for protein purification. Affinity markers such as hexahistidine, maltose-binding domain, influenza coat sequence, and glutathione-S-transferase can be attached to the protein to allow easy purification by passage over an appropriate affinity column. Isolated proteins can also be physically characterized using techniques such as proteolysis, nuclear magnetic resonance, and X-ray crystallography.

[00353] For example, supernatants from systems that secrete recombinant protein into culture media can first be concentrated using a commercially available protein concentration filter, for example, an Amicon or Millipore Pellicon ultrafiltration unit. After the concentration step, the concentrate can be applied to an appropriate purification matrix. Alternatively, an anion exchange resin can be employed, for example, a matrix or substrate that has pendant diethylaminoethyl (DEAE) groups. Matrices can be acrylamide, agarose, dextran, cellulose, or other types commonly used in protein purification. Alternatively, a cation exchange step can be employed. Suitable cation exchangers include various insoluble matrices comprising sulfopropyl or carboxymethylcellulose groups.Finally, one or more reversed-phase high-performance liquid chromatography (RP-HPLC) phases employing hydrophobic RP-HPLC media, for example, silica gel with methyl groups or other pendant aliphatic groups, can be used to further purify a CD123 / IL-3Ra binding agent. Some or all of the preceding purification steps, in various combinations, can also be employed to provide a homogeneous recombinant protein.

[00354] Recombinant protein produced in bacterial culture can be isolated, for example, by initial extraction of precipitates from Petition 870260060475, dated 06 / 19 / 2026, page 183 / 752 178 / 355 cell, followed by one or more steps of concentration, salting, aqueous ion exchange, or size exclusion chromatography. High-performance liquid chromatography (HPLC) may be employed for the final purification steps. Microbial cells used in the expression of a recombinant protein may be disrupted by any convenient method, including freeze-thaw cycle, sonication, mechanical disruption, or the use of cell lysing agents.

[00355] Methods known in the art for the purification of antibodies and other proteins also include, for example, those described in U.S. Patent Publication Nos. 2008 / 0312425, 2008 / 0177048 and 2009 / 0187005, each of which is hereby incorporated by reference in this document in its entirety.

[00356] In certain embodiments, the CD123 / IL-3Ra linking agent of the present invention has an N-terminal serine, which can be oxidized with an oxidizing agent to form an oxidized CD123 / IL-3Ra linking agent possessing an N-terminal aldehyde group.

[00357] Any suitable oxidizing agent may be used in step (a) of the methods described above. In certain embodiments, the oxidizing agent is a periodate. More specifically, the oxidizing agent is sodium periodate.

[00358] Excess molar equivalents of the oxidizing agent relative to the CD123 / IL-3Rα linking agent may be used. In certain embodiments, approximately 2-100, 5-80, 10-50, 1-10, or 5-10 molar equivalents of the oxidizing agent may be used. In certain embodiments, approximately 10 or approximately 50 equivalents of the oxidizing agent may be used. When a large amount of the oxidizing agent is used, a short reaction time is employed to avoid over-oxidation. For example, when 50 equivalents of the oxidizing agent are used, the oxidation reaction is carried out Petition 870260060475, dated 06 / 19 / 2026, page 184 / 752 179 / 355 for about 5 to about 60 minutes. Alternatively, when 10 equivalents of the oxidizing agent are used, the reaction is carried out for about 30 minutes to about 24 hours. In one embodiment, 5-10 molar equivalents of the oxidizing agent are used and the oxidation reaction is carried out for about 5 to about 60 minutes (e.g., about 10 to about 30 minutes, about 20 to about 30 minutes).

[00359] In certain embodiments, the oxidation reaction does not lead to significant non-segmented oxidation. For example, no significant extent (e.g., less than 20%, less than 10%, less than 5%, less than 3%, less than 2%, or less than 1%) of methionine and / or glycans are oxidized during the N-terminal serine oxidation process to generate the oxidized CD123 / IL-3Ra linking agent possessing an N-terminal aldehyde group.

[00360] In certain embodiments, the CD123 / IL-3Ra binding agent of the present invention has a recombinantly created Cys residue, such as a Cys residue corresponding to the 5th to last Cys, for example, SEQ ID NO: 54 or 56 (i.e., a Cys residue at EU / OU numbering position 442). Thus, the term cysteine ​​engineered antibody includes an antibody with at least one Cys that is not normally present in a given antibody light chain or heavy chain residue. Such a Cys, which may also be referred to as a genetically engineered Cys, can be designed using any conventional molecular biology or recombinant DNA technology (e.g., by replacing the coding sequence with a non-Cys residue in the target residue with a coding sequence for Cys).For example, if the original residue is Ser with a coding sequence of 5'-UCU-3', the coding sequence can be mutated (e.g., by site-directed mutagenesis) to 5'-UGU-3', which codes for Cys. In certain... Petition 870260060475, dated 06 / 19 / 2026, page 185 / 752 In certain embodiments, the genetically engineered Cys antibody of the invention has a genetically engineered Cys in the heavy chain. In certain embodiments, the genetically engineered Cys is within or near the CH3 domain of the heavy chain. In certain embodiments, the genetically engineered Cys corresponds to the 5th to last Cys, for example, SEQ ID NO: 54 or 56. The modified antibody heavy (or light) chain sequence can be inserted into a suitable recombinant expression vector to produce the engineered antibody with the engineered Cys residue instead of the original Ser residue. 3. Immunoconjugates

[00361] In a second aspect, the present invention also provides immunoconjugates comprising CD123 / IL-3Ra-binding agents described herein covalently linked to one or more molecules of the cytotoxic agents described herein.

[00362] In a first embodiment, the immunoconjugate of the present invention comprises CD123 / IL-3Ra binding agents (including the antibody, its antigen-binding fragment or the polypeptide comprising the antibody or its antigen-binding fragment) described herein covalently linked to a cytotoxic agent described herein through the ε-amino group of one or more lysine residues located in the CD123 / IL-3Ra binding agents.

[00363] In a specific embodiment of the first embodiment, the immunoconjugate of the present invention is represented by the following formula: CBA—(— CyL1) V wL(L1), where: CBA is a CD123 / IL-3Ra binding agent (e.g., a subject antibody or antigen-binding fragment described above, or a subject polypeptide described above) that is covalently linked via a lysine residue to CyL1; Petition 870260060475, dated 06 / 19 / 2026, p. 186 / 752 181 / 355 Wl is an integer from 1 to 20; and CyL1 is a cytotoxic compound represented by the following formula: (L1a), or a pharmaceutically acceptable salt thereof, where: The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M; W' is -NRe', Re' is - (CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Petition 870260060475, dated 06 / 19 / 2026, p. 187 / 752 182 / 355 Rx3 is an alkyl (C1-C6); L' is represented by the following formula: -NR5-PC(=O)-(CRaRb)mC(=O)- (B1'); or -NR5-PC(=O)-(CRaRb)mS-Zs1- (B2'); R5 is -H or an alkyl(C1-C3); P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; Ra and Rb, for each occurrence, are each independently -H, (C1-C3)alkyl, or a charged substituent or an ionizable group Q; m is an integer from 1 to 6; and Zs1 is selected from any of the following formulas: 'S0(b3); (b6), (b9); and in which: q is an integer from 1 to 5; and M is H+ or a cation.

[00364] In a specific 2amodality, for formula conjugates (L1), CyL1 is represented by the formula (L1a) or (L1a1); and the Petition 870260060475, dated 06 / 19 / 2026, page 188 / 752 The remaining 183 / 355 variables are described above in the specific modality 1.

[00365] In a specific 3a-embodiment, for conjugates of formula (L1), CyL1 is represented by formula (L1b) or (L1b1); and the remaining variables are described above in the specific 1a-embodiment. More specifically, Rx3 is an alkyl (C2-C4).

[00366] In a specific 4amodality, for conjugates of formula (L1), CyL1 is represented by formula (L1a); Ra and Rb are both H; R5 is H or Me, and the remaining variables are as described above in the specific 1amodality.

[00367] In a specific 5a modality, P is a peptide containing 2 to 5 amino residues; and the remaining various options are described in the 1st, 2nd or 4th specific modes. In a more specific mode, P is selected from the group that consists of Gly-GlyGly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, PheCit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N9-tosyl-Arg, Phe-N9-nitroArg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-AlaLeu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), Gly-Phe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-ValArg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, AlaD-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, and Met-Ala. Corn specifically, P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala, D-Ala-Ala or D-Ala-D-Ala.

[00368] In a specific 6amodality, Q is -SO3M; and the remaining variables are described above in specific 1a, 2a, 4a or 5amodalities or any more specific modalities described therein.

[00369] In a specific 7amodality, the immunoconjugate of the first modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 189 / 752 184 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 190 / 752 185 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 191 / 752 186 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 192 / 752 187 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 193 / 752 188 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 194 / 752 189 / 355 CBA MeO OMe CBA THE SOUND CBA OMe SOUND CBA THE OMe MeO CBA MeO OMe SOUND OMe MeO MeO Petition 870260060475, dated 06 / 19 / 2026, p. 195 / 752 190 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 196 / 752 191 / 355 or a pharmaceutically acceptable salt thereof, where Wl is an integer from 1 to 10; the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is -H; and when it is a single bond, X is -H, and Y is -OH or -SO3M. In a more specific embodiment, the double line — between N and C represents a double bond, X is absent and Y is -H. In another more specific embodiment, the double line — between N and C represents a single bond, X is -H and Y is SO3M.

[00370] In a specific modality, the immunoconjugate of the first modality is represented by the following formula: CBA—(--CyL2) vWL(L2), where: CBA is a CD123 / IL-3Ra binding agent described in the first aspect of the first invention (for example, an antibody subject or antigen-binding fragment described above, or a polypeptide subject described above), which is covalently linked to CyL2 via a lysine residue; Wl is an integer from 1 to 20; and Petition 870260060475, dated 06 / 19 / 2026, p. 197 / 752 192 / 355 CyL2 is a cytotoxic compound represented by the following formula: or a pharmaceutically acceptable salt thereof, where: The double line between N and C represents either a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or a protecting amine portion, and Y will be -OH or -SO3M; Rx1 and Rx2 are independently (C1-C6) alkyl; Reé -H or a (C1-C6)alkyl; W' is -NRe', Re'é - (CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Petition 870260060475, dated 06 / 19 / 2026, p. 198 / 752 193 / 355 Rké -H ou -Me; Zs1 is selected from any of the following formulas: the (b1);0(b2); o (b3); (b5), (b4); (b6), (b7); (b9); and in which: q is an integer from 1 to 5; and M is -H+ or a cation.

[00371] In a specific 9a-modality, for immunoconjugates of formula (L2), CyL2 is represented by formula (L2a) or (L2a1); and the remaining variables are as described above in the specific 8a-modality.

[00372] In a specific 10amodality, for immunoconjugates of formula (L2), CyL2 is represented by formula (L2b) or (L2b1); and the remaining variables are as described above in the specific 8amodality.

[00373] In a specific 11amodality, for immunoconjugates of formula (L2), Re is H or Me; Rx1 and Rx2 are independently (CH2)p- (CRfRg) -, where Rf and Rg are each independently -H Petition 870260060475, dated 06 / 19 / 2026, p. 199 / 752 194 / 355 or an alkyl (C1-C4); ep is 0, 1, 2 or 3; and the remaining variables are as described above in the 8th, 9th or 10th specific embodiment. More specifically, Rf and Rg are equal or different, and are selected from -H and -Me.

[00374] In a specific 12amodality, the immunoconjugate of the first modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 200 / 752 195 / 355 C 0 X To-.. Y 1 í| ] o LI j 1, MeC) d ° C ° hy'^'v H f 1 A IT j / MeC) d ° c 0 x rL 1 TrTL Í MeCt d ° XX / / ,O. / / N 7 / SX eL 1' MeO U 0 / ° / 'o X \ Lo0'^0! 7 7 Me MeO U 0 r XX / -x / NS ' Μχ-^dc l^^N~7^-^OMe MeO -' O ° H „S. / -,x-. ,N-'—CBA s 7 '' x 0 > Y NX Λ / 3⁄4 WL . J 1 X37^Ci . Π '' x 0 > Y ^vNX r '7 > WL . X\ N ' / VWW, WVX θ X 0 vd ° IJ WL J Λ so3m h —CBA OH d^'' rd Wl j ou Petition 870260060475, dated 06 / 19 / 2026, p. 201 / 752 196 / 355 or a pharmaceutically acceptable salt thereof, where Wl is an integer from 1 to 10; the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H; and when it is a single bond, X will be -H, and Y will be -OH or -SO3M. In a more specific embodiment, the double line — between N and C represents a double bond. In another more specific embodiment, the double line — between N and C represents a single bond, X is -H and Y is -SO3M.

[00375] In a specific 13amodality, the immunoconjugate of the first modality is represented by the following formula: CBA -í--CyL3)WL(L3), where: CBA is a CD123 / IL-3Ra binding agent described in the first aspect of the present invention (for example, an antibody subject or antigen-binding fragment described above, or a subject of its polypeptide described above), which is covalently linked to CyL3 via a Lys residue; Wl is an integer from 1 to 20; CyL3 is represented by the following formula: m' is 1 or 2; Petition 870260060475, dated 06 / 19 / 2026, p. 202 / 752 197 / 355 Ri and R2 are each independently H or a (C1-C3)alkyl group; Zs1 is selected from any of the following formulas: THE the / (CH2)q9 No (b3); (bi); so3m (b2); ° (b5), 'S0 (b4); (b7); (b8); and (b6), (b9), where: q is an integer from 1 to 5; and M is H+ or a cation.

[00376] In a specific 14amodality, for immunoconjugates of formula (L3), m' is 1 and R1 and R2 are both H; and the remaining variables are as described above in the specific 13amodality.

[00377] In a specific 15amodality, for immunoconjugates of formula (L3), m' is 2 and R1 and R2 are Me; and the remaining variables are as described above in the specific 13amodality.

[00378] In a specific 16amodality, the immunoconjugate of the first modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 203 / 752 198 / 355 Wl; or or a pharmaceutically acceptable salt thereof, where Wl is an integer from 1 to 10.

[00379] In a specific 17amodality, for immunoconjugates of the first modality, M is H+, Na+, or K+; and the remaining variables are as described above in any of the 1apara specific 16amodality or any more specific modalities described therein.

[00380] In any of the above 1apara specific 17amodalities, the antibody in question or its antigen-binding fragment may have one or more (e.g., substantially all or 100% of the Lys residues in any of the six CDR regions of light and heavy chain (if any) substituted for Arg. The antibody in question or its antigen-binding fragment may comprise an immunoglobulin heavy chain variable region (HCVR) possessing the amino acid sequence presented in the SEQs. Petition 870260060475, dated 06 / 19 / 2026, page 204 / 752 199 / 355 ID NO: 39 or 40; and a variable region of the immunoglobulin light chain (LCVR) having the amino acid sequence shown in SEQ ID NO: 41. The antibody in question or its antigen-binding fragment may also comprise an Ig HCVR with the amino acid sequence shown in SEQ ID NO: 34; and an Ig LCVR with the amino acid sequence shown in SEQ ID NO: 35. The antibody in question or its antigen-binding fragment may further comprise an Ig HCVR with the amino acid sequence shown in SEQ ID NO: 32, 34, 38, 39 or 40; and an Ig LCVR with the amino acid sequence shown in SEQ ID NO: 33, 35, 37, or 41. In certain embodiments, the second N-terminal residue of SEQ ID NO: 34 is Phe, while in other certain embodiments, the second N-terminal residue of SEQ ID NO: 34 is Val.

[00381] The immunoconjugates described in the first embodiment or any specific embodiments described herein may be prepared according to any method known in the art, see, for example, WO 2012 / 128868 and WO2012 / 112687, which are incorporated herein by reference.

[00382] In certain embodiments, immunoconjugates of the first embodiment may be prepared by a first method comprising the steps of reacting CBA with a cytotoxic agent possessing a reactive amine group.

[00383] In one embodiment, for the first method described above, the reaction is carried out in the presence of a reactive imine reagent, such as NaHSO3.

[00384] In one embodiment, for the first method described above, the cytotoxic agent possessing an amine-reactive reagent is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, page 205 / 752 200 / 355 (L1a'), or a pharmaceutically acceptable salt thereof, where: Lc' is represented by the following formula: -NR5-PC(=O)-(CRaRb)mC(=O)E (B1); or -NR5-PC(=O)-(CRaRb)mS-Zs(B2) C (= O) E is a reactive ester group, such as N-hydroxysuccinimide ester, N-hydroxysulfosuccinimide ester, nitrophenyl (e.g., 2- or 4-nitrophenyl) ester, dinitrophenyl (e.g., 2,4-dinitrophenyl) ester, sulfo-tetrafluorophenyl (e.g., 4-sulfo-2,3,5,6-tetrafluorophenyl ester) or pentafluorophenyl ester, preferably N-hydroxysuccinimide ester; Z is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 206 / 752 201 / 355 in which: q is an integer from 1 to 5; and U is -H or SO3M; and the remaining variables are described in any of the Γ for 7ae 17a specific modalities or any more specific modalities described therein.

[00385] In certain embodiments, immunoconjugates of the first embodiment may be prepared by a second method comprising the steps of: (a) reacting a cytotoxic agent with a linking compound having a reactive amine group and a reactive thiol group to form a cytotoxic agent-agent compound having the reactive amine group attached to it; and Petition 870260060475, dated 06 / 19 / 2026, page 207 / 752 202 / 355 (b) react CBA with the cytotoxic ligand compound.

[00386] In one embodiment, for the second method described above, the reaction in step (a) is carried out in the presence of an imine reactive reagent.

[00387] In one embodiment, for the second method described above, the cytotoxic agent-ligand compound is reacted with CBA without purification. Alternatively, the cytotoxic agent-ligand compound is first purified before reacting with CBA.

[00388] In certain embodiments, immunoconjugates of the first embodiment may be prepared by a third method comprising the steps of: (a) reacting CBA with a linking compound having a reactive amine group and a reactive thiol group to form a modified CBA having a reactive thiol group attached to it; and (b) reacting the modified CBA with the cytotoxic agent.

[00389] In one embodiment, for the third method described above, the reaction in step (b) is carried out in the presence of an imine reactive reagent.

[00390] In certain embodiments, immunoconjugates of the first embodiment can be prepared by a fourth method comprising the steps of reacting CBA, a cytotoxic compound and a linking compound possessing an amine reactive group and a thiol reactive group.

[00391] In one embodiment, for the fourth method, the reaction is carried out in the presence of an imine reactive agent.

[00392] In certain embodiments of the second, third, or fourth embodiment described above, the linking compound having a reactive amine group and a reactive thiol group is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 208 / 752 203 / 355 (a1L); (a2L); (a3L); (a4L); (a5L), (a6L), 0(a7L); (a8L); the N —\ u (a9L); e (a10L), where X is halogen; Jd -SH, -SSRd, or -SC (= O) Rg; Rd is phenyl, nitrophenyl, dinitrophenyl, carboxy-nitrophenyl, pyridyl, or nitropyridyl; Rg is an alkyl; and the remaining variables are as described above for formula (a1) - (a10); and the cytotoxic agent is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 209 / 752 204 / 355 or a pharmaceutically acceptable salt thereof, wherein the variables are as described in any of the specific modalities described therein, 8apara 12ae 17a.

[00393] In certain embodiments, for the second, third or fourth methods described above, the linking compound having a reactive amine group and a reactive thiol group is represented by any of the formula (a1L) - (a10L) and the cytotoxic agent is represented by the following formula:

[00394] Where the variables are described above in any of the 13 to 17 specific modalities and any other modalities Petition 870260060475, dated 06 / 19 / 2026, p. 210 / 752 205 / 355 specifics described therein.

[00395] In a second embodiment, the immunoconjugate of the present invention comprises an oxidized CD123 / IL-3Ra binding agent (including the antibody, its antigen-binding fragment, or the polypeptide comprising the antibody or its antigen-binding fragment) described in the first aspect of the present invention described herein (for example, oxidized antibody or its antigen-binding fragment, or its polypeptide) covalently linked to a cytotoxic agent described herein through one or more aldehyde groups located on the oxidized CD123 binding agent. The aldehyde groups located on the oxidized CD123 / IL-3Ra binding agent may be generated by the oxidation of one or more 2-hydroxyethylamine moieties of the CD123 / IL-3Ra binding agent, wherein the 2-hydroxyethylamine moiety is part of a serine, threonine, hydroxylysine, 4-hydroxyornithine, or 2,4-diamino-5-hydroxyvaleric acid.In one embodiment, the aldehyde groups can be generated by oxidation of the 2-hydroxyethylamine portion of one or more N-terminal serine residue(s) located in the CD123 / IL-3Ra linking agent (e.g., 2, 3, or even 4 N-terminal Ser residues of the light chains and / or the heavy chains).

[00396] In a specific embodiment of the first embodiment, the immunoconjugate of the present invention is represented by the following formula: CBAuGJcb'—Cys1) / Ws(Si). in which: CBA is the oxidized CD123 / IL-3Ro binding agent described in the first aspect of the invention (for example, an oxidized antibody of the subject or its antigen-binding fragment described above, or an oxidized polypeptide of the subject described above). Ws is 1, 2, 3, or 4; Petition 870260060475, dated 06 / 19 / 2026, p. 211 / 752 206 / 355 Jcb' is a moiety formed by the reaction of an aldehyde group in CBA with a reactive aldehyde group in Cys1, and is represented by the following formula: O c=ixNXs H η A s2n; h2h N-| s2 H5 H h2°"l·2where s1 is the site covalently bonded to CBA; and s2 is the site covalently bonded to Cys1; Cys1 is represented by the following formula: or a pharmaceutically acceptable salt thereof, where: Petition 870260060475, dated 06 / 19 / 2026, p. 212 / 752 207 / 355 The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M, and M will be H+ or a cation; R5 is -H or a (C1-C3)alkyl group; P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; Zd1 is missing, -C(=O)-NR9-, or -NR9-C(=O)-; R9 is -H or an alkyl group (C1-C3); Ra and Rb, for each occurrence, are independently -H, alkyl (C1C3), or a charged substituent or an ionizable group Q; re r' are independently integers from 1 to 6; W' is -NRe', Re' is - (CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx3 is an alkyl (C1-C6); L is -NR9-(CRaRb)r or absent; er is an integer from 0 to 6.

[00397] In a specific 2a-modality, for immunoconjugates of formula (S1), Cys1 is represented by the formula (S1a) or (S1a1); and the remaining variables are described above in the specific 1a-modality.

[00398] In a specific 3a-modality, for immunoconjugates of formula (S1), Cys1 is represented by formula (S1b) or (S1b1); and the remaining variables are described above in the specific 1a-modality. More specifically, Rx3 is an alkyl (C2-C4).

[00399] In a specific 4amodality, for immunoconjugates of formula (S1), Ra and Rb are H and R5 and R9 are H or Me; and the remaining variables are described above in the specific 1a or 2amodality. Petition 870260060475, dated 06 / 19 / 2026, p. 213 / 752 208 / 355

[00400] In a specific 5amodality, for immunoconjugated by formula (S1), P is a peptide containing 2 to 5 amino residues; and the various remaining ones are described as the 1st, 2nd or 4th specific mode. In a more specific mode, P is selected from the group consisting of Gly-Gly-Gly, Ala-Val, ValAla, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N9-tosyl-Arg, Phe-N9-nitro-Arg, Phe-Phe-Lys, DPhe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, AlaLeu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 57), GlyPhe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, ValD-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-ValD-Lys, D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-AlaD-Ala, Ala-Met, and Met-Ala. Ainda corn specifically, P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala, D-Ala-Ala or D-Ala-D-Ala.

[00401] In a specific 6a-modality, for immunoconjugates of formula (S1), Q is -SO3M; and the remaining variables are described above in specific 1a, 2a, 4a or 5a-modality.

[00402] In a specific 7a-modality, the immunoconjugate of the second modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 214 / 752 209 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 215 / 752 210 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 216 / 752 211 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 217 / 752 212 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 218 / 752 213 / 355 WS Petition 870260060475, dated 06 / 19 / 2026, p. 219 / 752 214 / 355 N—CH₂O₃H or a pharmaceutically acceptable salt thereof, wherein the double line = between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is H; and when it is a single bond, X is -H, and Y is -OH or -SO₃M. In a more specific embodiment, the double line — between N and C represents a double bond, X is absent and Y is -H. In another more specific embodiment, the double line = between N and C represents a single bond, X is -H and Y is -SO₃M.

[00403] In a specific embodiment, the immunoconjugates of the present invention are represented by the following formula: CBAuL· JCB'—Cys2Ws(S2); in which: CBA is the oxidized CD123 / IL-3Ra binding agent described in the first aspect of the invention (for example, an oxidized antibody of the subject or its antigen-binding fragment described above, or an oxidized polypeptide of the subject described above); Jcb' is a moiety formed by the reaction of an aldehyde group in CBA with a reactive aldehyde group in Cys2, and is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 220 / 752 215 / 355 . h2 I--C -N. I « N—IS2 H 5SZ where s1 is the site covalently bonded to CBA; and s2 is the site covalently bonded to Cys2; Cys2 is represented by the following formula: oRe / — Rx1^Ll-i N or a pharmaceutically acceptable salt thereof, where: The double line = between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a Petition 870260060475, dated 06 / 19 / 2026, p. 221 / 752 216 / 355 single bond, X will be -H or a protecting amine portion, and Y will be -OH or -SO3M; M is H+ or a cation; Rx1 is a (C1-C6)alkyl group; Reé -H or a (C1-C6)alkyl; W' is -NRe', Re' is - (CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx2 is an alkyl (C1-C6); Li is represented by the following formula: in which: s3 is the site covalently linked to the Jcb' group; s4 is the site covalently linked to the -S- group in Cys2; Za2 is missing, -C(=O)-NR9-, or -NR9-C(=O)-; R9 is -H or a (c1-c3)alkyl group; Q is H, a charged substituent or an ionizable group; Ra1, Ra2, Ra3, Ra4, for each occurrence, are independently H or (C1-C3)alkyl; and q1 and r1 are each independently an integer from 0 to 10, provided that q1 and r1 are not both 0.

[00404] In a more specific embodiment, Za2 is absent; q1 and r1 are independent of an integer from 0 to 3, provided that q1 and r1 are not both 0; and the remaining variables are as described above in the 8th specific embodiment. More specifically, Ra1, Ra2, Ra3, Ra4 are all -H.

[00405] In another more specific form, Za2 is -C (= O) -NH-, Petition 870260060475, dated 06 / 19 / 2026, p. 222 / 752 217 / 355 or -NHg-C (= O) -; q1 and r1 are each independently an integer from 1 to 6; and the remaining variables are as described above in the specific 8th modality. More specifically, Ra1, Ra2, Ra3, Ra4 are all -H.

[00406] In a specific 9a-modality, for immunoconjugate of formula (S2), Cys2 is represented by the formula (S2a) or (S2a1); and the remaining variables are as described above in the specific 8a-modality or any more specific modalities described therein.

[00407] In a specific 10a-modality, for immunoconjugate of formula (S2), Cys2 is represented by the formula (S2b) or (S2b1); and the remaining variables are as described above in the specific 8a-modality or any more specific modalities described therein.

[00408] In a specific 11a-modality, for immunoconjugate of formula (S2), -L1- is represented by the following formula: ; ; ; 0; or 0 or a pharmaceutically acceptable salt thereof, wherein R is H or -SO3M; and the remaining variables are as described above in the 8th, 9th or 10th specific embodiment or any more specific embodiments described therein.

[00409] In a specific embodiment, for immunoconjugate of formula (S2), Re is H or Me; and Rx1 is - (CH2)p- (CRfRg) - and Rx2 is - (CH2)p(CRfRg) -, where Rf and Rg are each independently -H or an alkyl (C1-C4); ep is 0, 1, 2 or 3. More specifically, Rf and Rg are the same or different, and are selected from -H and -Me.

[00410] In a specific 13amodality, the immunoconjugate of the second modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, p. 223 / 752 218 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 224 / 752 219 / 355 0 ( LzxA. HN \ ndxi0 < 0 Γ A ^x ,S^ HN X ζ^νχύ° °υύ MeO^·^ O / A HN A a H jS > \ ^Nrx° AA / N~q^^^^OMe MeO^'·^ OA A. HN \ v / X / ¼} X ΑΑ / Ν^ΑxΑx,-,ι^θ MeO^Av OA hn A a ^"χιο^°η MeO^x^ O HN^^ Y * ííX X-Q0 °JX ^^'Υ^ΑΜε MeO^^AH uh / X / V ζΝχ H2 / a / AA N—C w^CBA SAHX 0 XYM > rà ws . ; H uh / X / X χΝ. H2 / x / X^ / N—C ^~-CBA s Ah x 0 IYM > ιΆ . ws . J SO3M |_| Λ / x A χΝ. H ^N — C~ CBA 5 II A ° l ίΑ r / ¾ . Ws J SO3M |_| Λ ~ 1 __H , / X / N — C ™"CBA II A ° l / ¾ . Ws J SO3M Η Λ A χΝ. NC—CBA 'AY , ΝΑ Λ ;A ws . J SO3M Η Λ / XA A. SJ η H2 ^AY L NA > A' Ws . J Petition 870260060475, de 19 / 06 / 2026, pág. 225 / 752 220 / 355 Petition 870260060475, de 19 / 06 / 2026, pág. 226 / 752 221 / 355 Petition 870260060475, de 19 / 06 / 2026, pág. 227 / 752 222 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 228 / 752 223 / 355 WS Petition 870260060475, dated 06 / 19 / 2026, p. 229 / 752 224 / 355 Petition 870260060475, dated 06 / 19 / 2026, p. 230 / 752 225 / 355 Petition 870260060475, dated 06 / 19 / 2026, pp. 231 / 752 226 / 355 or a pharmaceutically acceptable salt thereof, wherein the double line = between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be H; and when it is a single bond, X will be -H; and Y will be -OH or -SO3M. Petition 870260060475, dated 06 / 19 / 2026, pp. 232 / 752 227 / 355 In a more specific embodiment, the double line between N and C represents a double bond, X is absent, and Y is -H. In another more specific embodiment, the double line between N and C represents a single bond, X is -H, and Y is -SO3M.

[00411] In a specific 14amodality, the immunoconjugate of the second modality is represented by the following formula: ΟΒΑνγΰΟΒ' — Cys3j / Ws (S3); where: CBA is the oxidized CD123 / IL-3Ra binding agent described in the first aspect of the invention (for example, an oxidized antibody of the subject or its antigen-binding fragment described above, or an oxidized polypeptide of the subject described above); Jcb' is a moiety formed by the reaction of an aldehyde group in CBA with a reactive aldehyde group in Cys3, and is represented by the following formula: where s1 is the site covalently bonded to CBA; and s2 is the site covalently bonded to Cys3; Cys3 is represented by the following formula: in which: Petition 870260060475, dated 06 / 19 / 2026, p. 233 / 752 228 / 355 m' is 1 or 2; Ri and R2 are each independently H or a (C1-C3)alkyl group; Li is represented by the following formula: in which: s3 is the site covalently linked to the Jcb' group; s4 is the site covalently linked to the -S- group in Cys3; Za2 is missing, -C(=O)-NRg-, or -NRg-C(=O)-; Rg is -H or an alkyl (C1-C3); Q is H, a charged substituent or an ionizable group; For each occurrence, Ra1, Ra2, Ra3, and Ra4 are independently either H or a (C1-C3)alkyl group; and q1 and ri are each independently an integer from 0 to i0, provided that qi and ri are not both 0. [004i2] In a more specific embodiment, Za2 is absent; qi and ri are independent of an integer from 0 to 3, provided that qi and ri are not both 0; and the remaining variables are as described above in the i4a specific embodiment. More specifically, Rai, Ra2, Ra3, Ra4 are all -H. [004i3] In another more specific embodiment, Za2 is -C (= O) -NH-, or -NHg-C (= O) -; qi and ri are each independently an integer of ia 6; and the remaining variables are as described above in the i4a specific embodiment. More specifically, Rai, Ra2, Ra3, Ra4 are all -H. [004i4] In a specific i5amodality, for immunoconjugates of formula (S3), m' is i; Ri and R2 are both H; and the remaining variables are as described above in the specific i4amodality or any more specific modalities described therein. Petition 870260060475, dated 06 / 19 / 2026, p. 234 / 752 229 / 355

[00415] In a specific 16amodality, for immunoconjugates of formula (S3), m' is 2; Ri and R2 are Me; and the remaining variables are as described above in the specific 14amodality or any more specific modalities described therein.

[00416] In a specific 17amodality, for immunoconjugates of formula (S3), -L1- is represented by the following formula: 0; or a pharmaceutically acceptable salt thereof, where R is H or SO3M and M is H+ or a cation.

[00417] In a specific 18amodality, the immunoconjugate of the second modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, pp. 235 / 752 230 / 355 or a pharmaceutically acceptable salt thereof; where DM is represented by the following formula:

[00418] In a specific 19amodality, the immunoconjugate of the second modality is represented by the following formula: CBA Ar JCB'—Cys4j / ws (S4) where: CBA is the oxidized CD123 / IL-3Ra binding agent described in the first aspect of the invention (e.g., an oxidized antibody from the subject or the Petition 870260060475, dated 06 / 19 / 2026, p. 236 / 752 231 / 355 its antigen-binding fragment described above, or an oxidized polypeptide subject described above); Jcb' is a moiety formed by the reaction of an aldehyde group in CBA with a reactive aldehyde group in Cys4, and is represented by the following formula: O s1 |—C=N^8H N N—s2H 5Ss1 s1 s1 N—s s2 H 5SZ H H2° I s2 where s1 is the site covalently bonded to CBA; and s2 is the site covalently bonded to Cys4; Cys4 is represented by the following formula: (S4a), Li' is represented by the following formula: Rb1 Rb3 Rb4 η1 Π R0Kb2; ouZb2'^ z \mi lí ^b5 Rb6O where: s3 is the site covalently linked to the Jcb' group; s4 is the site covalently linked to the -NMe- group in Cys4; Zbi and Zb2 are both absent, or one of Zbi and Zb2 is absent and the other is -CH2-O- or -O-CH2-; Zbi' and Zb2' are each independently absent. Petition 870260060475, dated 06 / 19 / 2026, pp. 237 / 752 232 / 355 CH2-O-, -O-CH2-, -NRg-C(=O)-CH2-, or -CH2-C(=O)-NRg-; Rg is H or alkyl (C1-C3); n1 and ml are each independently an integer from 1 to 6; One of Ei and E2 is -C(=O)-, and the other is -NRg-; or one of Ei and E2 is -C(=O)- or -NRg-, and the other is absent; P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; and Rbi, Rb2, Rb3, Rb4, Rb5 and Rb6, for each occurrence, are each independently either H or an alkyl group (C1-C3). [004ig] In a 20a-specific modality, for immunoconjugates of formula (S4), Rbi, Rb2, Rb3, Rb4, Rb5 and Rb6 are all H; and the remaining variables are as described above in the 1a-specific modality.

[00420] In a specific 2iamodality, for immunoconjugates of formula (S4), Rg is H; and the remaining variables are as described above in the specific 20iamodality. [0042i] In a specific 22amodality, for immunoconjugates of formula (S4), Zbi' and Zb2' are both absent; or Zbi' is -CH2-O- and Zb2' is absent; or Zbi' is -CH2-C (= O) -NRg-; and Zb2' is -O-CH2- or absent; and the remaining variables are as described above in the iga, 20a or 2ia specific modality.

[00422] In a specific 23a-modality, for immunoconjugates of formula (S4), P is a peptide containing 2 to 5 amino acid residues; and the remaining variables are as described above in the iga, 20a, 2ia or specific 22a-modality. In a more specific embodiment, P is selected from the group consisting of Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-Ng-tosyl-Arg, Phe-Ng-nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ Petition 870260060475, dated 06 / 19 / 2026, pp. 238 / 752 233 / 355 ID NO: 57), Gly-Phe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, ArgArg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, Ala-DAla, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, and Met-Ala; and the remaining variables are as described above in the 23specific modality. Even more specifically, P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala, D-Ala-Ala, or D-Ala-D-Ala.

[00423] In a specific 24amodality, the immunoconjugate of the second modality is represented by the following formula: WS. ; Petition 870260060475, dated 06 / 19 / 2026, p. 239 / 752 234 / 355 Petition 870260060475, dated 06 / 19 / 2026, pp. 240 / 752 235 / 355 or a pharmaceutically acceptable salt thereof, wherein DM is represented by the following structural formula:

[00424] In a specific 25amodality, for immunoconjugates of the first modality, M is H+, Na+, or K+; and the remaining variables are as described above in any of the 1apara specific 24amodality or any more specific modalities described therein.

[00425] In any of the above 1apara specific 25amodality, the oxidized antibody or its antigen-binding fragment may have 1, 2, 3, or up to 4 N-terminal 2-hydroxyethylamine moieties oxidized to aldehyde group(s), to covalently bind to a cytotoxic agent described herein. The N-terminal 2-hydroxyethylamine moiety may be part of a serine, threonine, hydroxylysine, 4-hydroxyornithine, or 2,4-diamino-5-hydroxyvaleric acid residue, preferably Ser or Thr. To simplify, the description below, including the oxidation reaction and any subsequent conjugation with ligands or cytotoxic agents, can refer to Ser as a specific example of such N-terminal portions of 2 Petition 870260060475, dated 06 / 19 / 2026, pp. 241 / 752 236 / 355 hydroxyethylamine, but should generally be interpreted as referring to all N-terminal 2-hydroxyethylamine portions. The antibody in question or its antigen-binding fragment may comprise an immunoglobulin heavy chain variable region (HCVR) having the amino acid sequence shown in SEQ ID NO: 38; and an immunoglobulin light chain variable region (LCVR) having the amino acid sequence shown in SEQ ID NO: 33, 35, 37 or 41 (preferably SEQ ID NO: 35 or 37). The antibody in question or its antigen-binding fragment may also comprise an HCVR Ig with the amino acid sequence shown in SEQ ID NO: 32, 34, 38, 39 or 40 (preferably SEQ ID NO: 34); and an LCVR Ig with the amino acid sequence shown in SEQ ID NO: 37.The antibody in question or its antigen-binding fragment may further comprise an Ig heavy chain (HC) region having the amino acid sequence shown in SEQ ID NO: 53 or 56; and a variable region of the Ig LCVR light chain having the amino acid sequence shown in SEQ ID NO: 33, 35, 37 or 41 (preferably SEQ ID NO: 35 or 37). The antibody in question or its antigen-binding fragment may also comprise an Ig HC region having the amino acid sequence shown in SEQ ID NO: 48, 50, 53, 54, 56, 59 or 60 (preferably SEQ ID NO: 53); and an LCVR Ig with the amino acid sequence presented in SEQ ID NO: 37. In certain embodiments, the second N-terminal residue of SEQ ID NOs: 34, 38, 50, 53, 54, or 56 is Phe, while in other embodiments, the second N-terminal residue of SEQ ID NOs: 34, 38, 50, 53, 54, or 56 is Val.

[00426] In certain embodiments, immunoconjugates of the second embodiment may be prepared by a first method comprising the reaction of a CD123 / IL-3Ra binding agent. Petition 870260060475, dated 06 / 19 / 2026, pp. 242 / 752 237 / 355 oxidized having an N-terminal aldehyde described in the first aspect of the invention with a cytotoxic agent having a reactive aldehyde group.

[00427] In certain embodiments, the immunoconjugates of the second embodiment can be prepared by a second method comprising reacting an oxidized CD123 / IL-3Ra binding agent possessing an N-terminal aldehyde described in the first aspect of the invention with a binding compound having a reactive aldehyde group to form a modified CD123 / IL-3Ra binding agent possessing a ligand attached thereto, followed by reacting the modified CD123 / IL-3Ra binding agent with a cytotoxic agent.

[00428] In certain embodiments, the immunoconjugates of the second embodiment can be prepared by a third method comprising contacting an oxidized CD123 / IL-3Ra binding agent having an N-terminal aldehyde described in the first aspect of the invention with a cytotoxic agent followed by the addition of a binding compound having a reactive aldehyde group.

[00429] In certain embodiments, immunoconjugates of the second embodiment may be prepared by a fourth method comprising the steps of: (a) oxidation of a CD123 / IL-3Ra binding agent having an N-terminal 2-hydroxyethylamine moiety (e.g., Ser / Thr) with an oxidizing agent to form an oxidized CD123 / IL-3Ra binding agent having an N-terminal aldehyde group; and (b) reacting the oxidized CD123 / IL-3Ra binding agent having the N-terminal aldehyde group with a cytotoxic agent possessing a reactive aldehyde group.

[00430] In certain embodiments, immunoconjugates of the second embodiment may be prepared by a fifth method that Petition 870260060475, dated 06 / 19 / 2026, pp. 243 / 752 238 / 355 comprises the following steps: (a) oxidation of a CD123 / IL-3Ra linking agent having an N-terminal 2-hydroxyethylamine moiety (e.g., Ser / Thr) with an oxidizing agent to form an oxidized CD123 / IL-3Ra linking agent having an N-terminal aldehyde group; (b) reacting the oxidized CD123 / IL-3Ra binding agent having the N-terminal aldehyde group with a linking compound having a reactive aldehyde group to form a modified CD123 / IL-3Ra binding agent having a ligand attached to it, followed by reacting the modified CD123 / IL-3Ra binding agent with a cytotoxic agent.

[00431] In certain embodiments, immunoconjugates of the second embodiment may be prepared by a sixth method comprising the steps of: (a) oxidation of a CD123 / IL-3Ra linking agent having an N-terminal 2-hydroxyethylamine moiety (e.g., Ser / Thr) with an oxidizing agent to form an oxidized CD123 / IL-3Ra linking agent having an N-terminal aldehyde group; (b) contacting the oxidized CD123 / IL-3Ra linking agent possessing the N-terminal aldehyde group with a cytotoxic agent followed by the addition of a linking compound possessing a reactive aldehyde group.

[00432] In one embodiment, for the first or fourth method described above, the cytotoxic agent possessing a reactive aldehyde group is represented by the following formula: (S1a'), Petition 870260060475, dated 06 / 19 / 2026, pp. 244 / 752 239 / 355 or a pharmaceutically acceptable salt thereof, where JcBé is represented by the following formula: o λ H ; nh2£ ^NH, í—° ; ou * ; and the remaining variables are described above in any of the specific modalities 1 to 7 and 25 and any more specific modalities described therein.

[00433] In another embodiment, for the first or fourth method described above, the cytotoxic agent possessing a reactive aldehyde group is represented by the following formula: (S4a'), or its pharmaceutically acceptable salt, where Jcb is as described Petition 870260060475, dated 06 / 19 / 2026, pp. 245 / 752 240 / 355 above and the remaining variables are described in any of the 19 to 25 specific modalities and any more specific modalities described therein.

[00434] In one embodiment, for the second, third, fifth, or sixth method described above, the linking compound is represented by the following formula: (Lsa) where Jd -SH, -SSRd, or -SC (= O) Rg; R is phenyl, nitrophenyl, dinitrophenyl, carboxy-nitrophenyl, pyridyl or nitropyridyl; R is an alkyl; Jcb is as described above; the cytotoxic agent is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, pp. 246 / 752 241 / 355 and the remaining variables are described above in any of the 8apara 13ae 25a specific modalities and any more specific modalities described therein.

[00435] In another embodiment, for the second, third, fifth or sixth method described above, the binding compound is represented by the formula (Lsa) above; the cytotoxic compound is represented by the following formula: and the remaining variables are as described in any of the 14apara 18ae 25a specific modalities and any more specific modalities described therein.

[00436] In one embodiment, for the first or fourth methods described above, the cytotoxic agent is reacted with an imine-reactive reagent, such as NaHSO3, to form a modified cytotoxic agent before reacting with the oxidized CD123 / IL-3Ra binding agent possessing the N-terminal aldehyde. In one embodiment, the modified cytotoxic agent is not purified before reacting with the oxidized CBA possessing the N-terminal aldehyde. Alternatively, the modified cytotoxic agent is purified before reacting with the oxidized CBA possessing the N-terminal aldehyde.

[00437] In another modality, for the second or fifth method Petition 870260060475, dated 06 / 19 / 2026, pp. 247 / 752 242 / 355 described above, the cytotoxic agent is reacted with an imine-reactive reagent, such as NaHSO3, to form a modified cytotoxic agent before reacting with the modified CD123 / IL-3Ra binding agent possessing a ligand attached to it. In one embodiment, the modified cytotoxic agent is purified before reacting with the modified CD123 / IL-3Ra binding agent possessing a ligand attached to it. Alternatively, the modified cytotoxic agent is not purified before reacting with the oxidized CD123 / IL-3Ra binding agent possessing the N-terminal aldehyde.

[00438] In yet another embodiment, for the third or sixth methods described above, the reaction of the oxidized CD123 / IL-3Ra binding agent, the cytotoxic agent and the binding compound are carried out in the presence of an imine reactive reagent, such as NaHSO3.

[00439] Any suitable oxidizing agent may be used in step (a) of the fourth, fifth or sixth method described above. In certain embodiments, the oxidizing agent is a periodate. More specifically, the oxidizing agent is sodium periodate.

[00440] Excess molar equivalents of the oxidizing agent relative to the CD123 / IL-3Ra linking agent may be used. In certain embodiments, approximately 2-100, 5-80, 10-50, 1-10, or 5-10 molar equivalents of the oxidizing agent may be used. In certain embodiments, approximately 10 or approximately 50 equivalents of the oxidizing agent may be used. When a large amount of the oxidizing agent is used, a short reaction time is used to avoid over-oxidation. For example, when 50 equivalents of the oxidizing agent are used, the oxidation reaction is carried out for about 5 to about 60 minutes. Alternatively, when 10 equivalents of the oxidizing agent are used, the reaction is carried out for about 30 minutes to about 24 hours. In one embodiment, 5-10 molar equivalents of the oxidizing agent are used and the reaction of Petition 870260060475, dated 06 / 19 / 2026, pp. 248 / 752 The 243 / 355 oxidation process is carried out for approximately 5 to approximately 60 minutes (for example, approximately 10 to approximately 30 minutes, approximately 20 to approximately 30 minutes).

[00441] In certain embodiments, a catalyst is present in the reaction in the first, second, or third method described above or in the reaction of step (b) in the fourth, fifth, or sixth method described above. Any suitable catalyst in the art may be used. In one embodiment, the catalyst is an aniline or substituted aniline. Exemplary aniline catalysts include, but are not limited to, aniline, o-phenylenediamine, m-phenylenediamine, 3,5-diaminobenzoic acid, p-phenylenediamine, 2-methyl-p-phenylenediamine, N-methylp-phenylenediamine, o-aminophenol, m-aminophenol, p-aminophenol, p-methoxyaniline, 5-methoxyanthranilic acid, o-aminobenzoic acid, and 4-aminophenethyl alcohol. In one embodiment, the catalyst is 4-aminophenethyl alcohol. In certain embodiments, the reaction of step (b) is carried out at a pH of about 5.0 to about 6.5. In certain embodiments, the reaction of step (b) is carried out at a pH of about 5.0.

[00442] In certain embodiments, for the reaction in the first, second, or third method described above or in the reaction of step (b) in the fourth, fifth, or sixth method described above, the compound possessing an aldehyde reactive group (e.g., cytotoxic agent, or the binding compound described herein) is used in molar excess relative to the oxidized cell-binding agent (e.g., oxidized antibody or oxidized antigen-binding moiety). In certain embodiments, the ratio of the compound possessing an aldehyde reactive group to the oxidized cell-binding agent is between about 10:1 and about 1.1:1, between about 5:1 and about 2:1. In one embodiment, the ratio is about 4:1.

[00443] In a third embodiment, the immunoconjugates of the present invention comprise a CD123 / IL binding agent. Petition 870260060475, dated 06 / 19 / 2026, pp. 249 / 752 244 / 355 3Ra (including antibody, its antigen-binding fragment or polypeptide comprising the antibody or its antigen-binding fragment) described in the first aspect of the invention covalently linked to a cytotoxic agent described herein through the thiol group (-SH) of one or more cysteine ​​residues located in the CD123-binding agent.

[00444] In a specific 1a-modality, the immunoconjugate of the third modality is represented by the following formula: CBA-(—Cyc1)Wc(Cl), where: CBA is a CD123 / IL-3Rα binding agent described in the first aspect of the invention (for example, an antibody subject or antigen-binding fragment described above, or a polypeptide subject described above), which is covalently linked to CyC1 via a cysteine ​​residue; WC is 1 or 2; CyC1 is represented by the following formula 1 O o \ * ΓΓ V Γ OMe MeO p ^==7 OO Rs n (CRaRb)m 1 Γ\ ° 0 \ ,x \\] LC—W (C1a1); (C1b), or Petition 870260060475, dated 06 / 19 / 2026, pp. 250 / 752 245 / 355 (C1b1) or a pharmaceutically acceptable salt thereof, where: The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M, and M will be H+ or a cation; R5 is -H or a (C1-C3)alkyl group; P is an amino acid residue or a peptide containing 2 to 20 amino acid residues; Ra and Rb, for each occurrence, are independently -H, alkyl (C1C3), or a charged substituent or an ionizable group Q; W' is -NRe', Re' is - (CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Rké -H ou -Me; Rx3 is an alkyl group (C1-C6); and, LC is represented by: where s1 is the site covalently bonded to CBA, and s2 is the site covalently bonded to the -C(=O)- group in CyC1; where: R19 and R20, for each occurrence, are independently -H or an alkyl(C1-C3); m is an integer between 1 and 10; and Petition 870260060475, dated 06 / 19 / 2026, pp. 251 / 752 246 / 355 Rhé -H or an alkyl group (C1-C3).

[00445] In a specific 2amodality, for immunoconjugates of formula (Ci), CyC1 is represented by the formula (C1a) or (C1a1); and the remaining variables are described above in the specific 1amodality.

[00446] In a specific 3amodality, for immunoconjugates of formula (C1), CyC1 is represented by the formula (C1b) or (C1b1); and the remaining variables are described above in the specific 1amodality.

[00447] In a specific 4a-modality, for immunoconjugates of formula (C1), CyC1 is represented by formula (C1a) or (C1a1); Ra and Rb are both H; R5 is H or Me, and the remaining variables are as described above in the specific 1a or 2a-modality.

[00448] In a specific 5modality, for immunoconjugates of formula (C1), P is a peptide containing 2 to 5 amino acid residues; and the remaining variables are described as above in the 1st, 2nd or 4th specific modality. In a more specific modality, P is selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-N-Arg-9 Phe-N9-nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, GlyPhe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Leu-Ala-Leu (SEQ ID NO: 55), β-Ala-Ala-Leu (SEQ ID NO: 57), Gly-Phe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-Lys, D-L-D-Val, D-Val D-Arg-D-Arg, No-No, No-D-No, D-No-No, D-No-D-No, No-Met, and No-No. In another more specific modality, P is Gly-Gly-Gly, AlaVal, Ala-Ala, Ala-D-Ala, D-Ala-Ala or D-Ala-D-Ala.

[00449] In a specific 6a-modality, for immunoconjugates of formula (C1), Q is -SO3M; and the remaining variables are as described above in the 1a, 2a, 4a or 5a-specific modality or any more specific modalities described therein.

[00450] In a specific 7amodality, for immunoconjugates of Petition 870260060475, dated 06 / 19 / 2026, pp. 252 / 752 247 / 355 formula (Ci), R19 and R20 are both H; em is an integer from 1 to 6; and the remaining variables are described above in 1a, 2a, 3a, 4a, 5a or 6a specific modality or any more specific modalities described therein.

[00451] In a specific 8amodality, for immunoconjugates of formula (C1), -L-LC- is represented by the following formula: and the remaining variables are described above in specific modalities 1a, 2a, 3a, 4a, 5a, 6a or 7a, or any more specific modalities described therein.

[00452] In a specific 9a-modality, the immunoconjugate of the third modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, pp. 253 / 752 248 / 355 or a pharmaceutically acceptable salt thereof, wherein the double line between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is H; and when it is a single bond, X is -H, and Y is -OH or -SO3M. In a more specific embodiment, the double line between N and C represents a double bond, X is absent, and Y is -H. In another more specific embodiment, the double line between N and C represents a single bond, X is -H, and Y is -SO3M.

[00453] In a specific 10th modality, the immunoconjugate of the third modality is represented by the following formula: (C2), where: CBA is a CD123 / IL-3Ra binding agent described in the first aspect of the invention (for example, an antibody subject or antigen-binding fragment described above, or a polypeptide subject described above), which is linked Petition 870260060475, dated 06 / 19 / 2026, pp. 254 / 752 249 / 355 covalently to CyC2 through a cysteine ​​residue; WC is 1 or 2; CyC2 is represented by the following formula: (C2a), (C2a1), (C2b), or (C2b1), or a pharmaceutically acceptable salt thereof, where: The double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X will be absent and Y will be -H or a (C1-C4)alkyl group; and when it is a single bond, X will be -H or an amine protecting portion, and Y will be -OH or -SO3M, and M will be H+ or a cation; Rx1 is a (C1-C6)alkyl group; Reé -H or a (C1-C6)alkyl; W' is -NRe'; Re'é - (CH2-CH2-O)n-Rk; n is an integer from 2 to 6; Petition 870260060475, dated 06 / 19 / 2026, pp. 255 / 752 250 / 355 Rké -H ou -Me; Rx2 is an alkyl (Ci-Ce); LC' is represented by the following formula: or where si is the site covalently linked to CBA and s2 is the site covalently linked to the -S- group in CyC2; Z is -C(=O)-NRg-, or -NRg-C(=O)-; Q is -H, a charged substituent, or an ionizable group; Rg, R10, Rii, R12, R13, Rig, R20, R21 and R22, for each occurrence, are independently either -H or a (C1-C3)alkyl group; qer, for each occurrence, is independently an integer between 0 and i0; men are, each one independently, an integer between 0 and i0; Rhé -H or a (C1-C3)alkyl; and P' is an amino acid residue or a peptide containing 2 to 20 amino acid residues.

[00454] In a more specific embodiment, qer are each independently an integer between ia 6, more specifically, an integer between ia 3. More specifically, Ri0, Rii, Ri2 and Ri3 are all H.

[00455] In another more specific embodiment, men are each independently an integer between ie 6, more specifically, an integer between ia 3. More specifically, Petition 870260060475, dated 06 / 19 / 2026, pp. 256 / 752 251 / 355 Rig, R20, R21 and R22 are all H.

[00456] In a specific 11a-modality, for immunoconjugates of formula (C2), CyC2 is represented by formula (C2a) or (C2a1); and the remaining variables are as described above in the specific 10a-modality or any more specific modalities described therein.

[00457] In a specific 12a-modality, for immunoconjugates of formula (C2), CyC2 is represented by formula (C2b) or (C2b1); and the remaining variables are as described above in the specific 10a-modality.

[00458] In a specific 13a-embodiment, for immunoconjugates of formula (C2), P' is a peptide containing 2 to 5 amino acid residues; and the remaining variables are as described in the specific 10a, 11a or 12a-embodiment or any more specific embodies described therein. In a more specific embodiment, P' is selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, LysLys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp, Cit, Phe-Ala, Phe-Ng-tosylArg, Phe-Ng-nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, LeuAla-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu (SEQ ID NO: 55), βAla-Leu-Ala-Leu (SEQ ID NO: 57), Gly-Phe-Leu-Gly (SEQ ID NO: 73), Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, DVal-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-DArg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, and Met-Ala. In another more specific embodiment, P' is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala, D-Ala-Ala or D-Ala-D-Ala.

[00459] In a specific 14amodality, for immunoconjugates of formula (C2), -LC'- is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, pp. 257 / 752 252 / 355

[00460] In a specific 15a-modality, for immunoconjugates of (C2), RfH or Me; Rx1 is - (CH2)p- (CRfRg) - and Rx2 is - (CH2)p- (CRfRg) -, where Rf and Rg are each independently -H or an alkyl (C1-C4); ep is 0, 1, 2 or 3; and the remaining variables are as described above in the 10a, 11a, 12a, 13a, or 14a-specific modality. More specifically, Rf and Rg are the same or different, and are selected from -H and -Me.

[00461] In a specific 16amodality, the immunoconjugate of the third modality is represented by the following formula: Petition 870260060475, dated 06 / 19 / 2026, pp. 258 / 752 253 / 355 Petition 870260060475, dated 06 / 19 / 2026, pp. 259 / 752 254 / 355 ; or a pharmaceutically acceptable salt thereof, wherein the double line = between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is H; and when it is a single bond, X is -H, and Y is -OH or -SO3M. In a more specific embodiment, the double line — between N and C represents a double bond, X is absent and Y is -H. In another specific embodiment, the double line — between N and C represents a single bond, X is -H and Y is -SO3M.

[00462] In a specific 17a-modality, the immunoconjugate of the third modality is represented by the following formula: CBA 4— Cyc3)Wc(C3), where:

[00463] CBA is a CD123 / IL-3Ra binding agent described in the first aspect of the invention (for example, an antibody subject or antigen-binding fragment described above, or a polypeptide subject described above), which is covalently linked to CyC3 via a cysteine ​​residue; WC is 1 or 2; CyC3 is represented by the following formula: 0s ci \ ° R1R2cí MeO, L \° ^''4 s'1MeO HO η(C3a) where: Petition 870260060475, dated 06 / 19 / 2026, p. 260 / 752 255 / 355 m' is 1 or 2; Ri and R2 are each independently either -H or a (C1-C3)alkyl group; LC' is represented by the following formula: the ; ; in which: si is the s...

Claims

1. Use of an immunoconjugate, characterized in that it is for the manufacture of a pharmaceutical composition or medicament for treating an individual with acute myeloid leukemia (AML), wherein the immunoconjugate is represented by the following formula: or a pharmaceutically acceptable salt thereof, wherein the double line — between N and C represents a single bond or a double bond, provided that, when it is a double bond, X is absent and Y is -H, and when it is a single bond, X is -H and Y is -SO3M, M is H+, Na+ or K+; and wherein CBA is an antibody or an antigen-binding fragment thereof, comprising: (a) a variable region of the immunoglobulin heavy chain, comprising a CDR1 with an amino acid sequence established at SEQ ID NO: 5, a CDR2 with an amino acid sequence established at SEQ ID NO: 8 and a CDR3 with an amino acid sequence established at SEQ ID NO: 11;and (b) a variable region of the immunoglobulin light chain, comprising a CDR1 with an amino acid sequence established in SEQ ID NO: 20, a CDR2 with an amino acid sequence established in SEQ ID NO: 21 and a CDR3 with a Petition 870260060475, dated 19 / 06 / 2026, page 362 / 752; 2 / 2 amino acid sequence established in SEQ ID NO:

22.

2. Use of an immunoconjugate, according to claim 1, characterized in that CBA is an antibody or an antigen-binding fragment thereof, comprising: (a) a variable immunoglobulin heavy chain region having the amino acid sequence established in SEQ ID NO: 34; and (b) a variable immunoglobulin light chain region having the amino acid sequence established in SEQ ID NO:

35.

3. Use of an immunoconjugate, according to claim 2, characterized in that Xaa, the second N-terminal residue of SEQ ID NO: 34, is Phe, or Xaa, the second N-terminal residue of SEQ ID NO: 34, is Val.

4. Use of the immunoconjugate, according to claim 1, characterized in that CBA is an antibody comprising: (a) an immunoglobulin heavy chain with the amino acid sequence set forth in SEQ ID NO: 54; and (b) an immunoglobulin light chain with the amino acid sequence set forth in SEQ ID NO:

51.

5. Use of the immunoconjugate, according to claim 4, characterized in that Xaa, the second N-terminal residue of SEQ ID NO: 54, is Phe, or Xaa, the second N-terminal residue of SEQ ID NO: 54, is Val.

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