Crystalline form, pharmaceutical composition, use of the crystalline form, and method for preventing or treating.

Abstract

The present specification relates to a crystalline form of (3S)-2-[(5-amino-6-fluoro-1H- pyrrolo[3,2-b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]-1,2'- dione, and to compositions and uses thereof.

Description

Crystalline form, pharmaceutical composition, use of the crystalline form, and method for preventing or treating.

[001] This descriptive report claims the benefit of priority of European patent application no. 023161547,7, filed on 13 March 2023, the content of which is incorporated herein by reference in its entirety for all purposes. TECHNICAL FIELD

[002] This descriptive report refers to a crystalline form of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]-1,2'-dione, and to its compositions and uses. BACKGROUND

[003] Protein arginine methyltransferase 5 (PRMT5) is a member of the PRMT family of arginine methyltransferase enzymes that catalyze the addition of methyl groups to the guanidine motif of arginine residues, using S-adenosyl-L-methionine (SAM) as a methyl donor. PRMT5 is a type II arginine methyltransferase that symmetrically dimethylates the guanidine group of arginine residues, thus converting an arginine NH2 guanidine group into an NMe2 group. PRMT5 methylates various substrates, including histone and non-histone proteins, and in doing so regulates processes such as RNA splicing, cell proliferation, and DNA repair. Significantly, PRMT5 is overexpressed in several types of cancer and has been identified as a candidate for therapeutic intervention through the development of small molecules that inhibit PRMT5 methyltransferase activity (see, for example, Kim et al., (2020) Cell Stress 4(8) 199-2151).

[004] Cyclin-dependent kinase inhibitor 2A (CDKN2A) is a tumor suppressor gene that is homozygous deleted in approximately 15% of cancers. Loss of the locus on chromosome 9p21 Petition 870250081337, dated 10 / 09 / 2025, page 10 / 64 2 / 47 results in the co-deletion of several additional genes, including the gene encoding methylthioadenosine phosphorylase (MTAP). MTAP is a metabolic enzyme involved in methionine salvage, and the loss of MTAP results in increased concentrations of the MTAP substrate methylthioadenosine (MTA) in CDKN2A / MTAP-deleted cancer cells. MTA itself acts as a weak inhibitor of PRMT5, and the accumulation of MTA in CDKN2A / MTAP-deleted cancer cell lines leads to partial inhibition of PRMT5 activity. The compromised PRMT5 activity makes CDKN2A / MTAP-deleted cancer cells susceptible to further PRMT5 targeting, for example, using short-loop RNA (shRNA). A “collateral vulnerability” has been identified in cancer, where tumors with CDKN2A / MTAP deletion can be selectively targeted through PRMT5 inhibition (see Marjon et al., (2016) Cell Reports 15, 574-587; Mavrakis et al., (2016) Science 11;351(6278):1208-13; Kryukov et al., (2016) Science 11;351(6278):1214-8).

[005] PRMT5 inhibitors that are “MTA synergistic” (i.e., inhibitors that bind to PRMT5, preferably in the presence of MTA) exert a greater inhibitory effect on PRMT5 in environments where relatively high concentrations of MTA are present, such as tumor cells with CDKN2A / MTAP deletion, and not in healthy tissues. Consequently, PRMT5 inhibitors that are “MTA synergistic” must possess a high therapeutic index (and low off-target toxicity), as their antiproliferative activity will selectively manifest in target tumor cells with CDKN2A / MTAP deletion. Several PRMT5 inhibitors that are “MTA synergistic” have entered clinical trials, such as MRTX-1719 (NCT05245500); TNG-908 (NCT05275478); TNG-462 (NCT05732831); AMG-193 (NCT05094336, NCT05094336); and AZD3470 (NCT06130553; NCT06137144). However, to date, no PRMT5 inhibitor, much less PRMT5 inhibitors "synergistic with MTA", has been approved for Petition 870250081337, dated 10 / 09 / 2025, page 11 / 64 3 / 47 Therapeutic use. Document PCT / EP2022 / 075248 (published as International Publication Leaflet WO2023 / 036974) discloses PRMT5 inhibitors, particularly PRMT5 inhibitors synergistic with MTA, including the compound (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl]-1'but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]-1,2'-dione (hereinafter referred to as Compound (I)): F Compound (I), together with its activity as an enzyme inhibitor PRMT5 in assays with MTA present (IC50 0.006 μM) and MTA absent (IC50 0.027 μM), its activity in wild-type HCT116 cells (IC50 0.2 μM) and knockout HCT116 MTAP cells (IC50 0.0059 μM), and its activity against cell proliferation in wild-type HCT116 cells (IC50 6.1 μM) and knockout HCT116 MTAP cells (IC50 0.24 μM). Therefore, Compound (I) is an inhibitor of PRMT5 and is, in particular, a PRMT5 inhibitor synergistic with MTA. To further study the therapeutic potential of Compound (I), it is desirable to have solid forms of the compound with properties suitable for pharmaceutical development.

[006] In the formulation of pharmaceutical substances, it is important that the pharmaceutical substance (active compound) be in a form in which it can be conveniently handled and processed. This is important not only from the point of view of obtaining a commercially viable manufacturing process for the pharmaceutical substance itself, but also from the point of view of the subsequent manufacture of pharmaceutical formulations. Petition 870250081337, dated 10 / 09 / 2025, page 12 / 64 4 / 47 comprising the active compound and suitable excipients. The chemical and physical stability of the active compound are important factors in determining the suitability of a solid dosage form for use in the development of pharmaceutical formulations. The active compound, and the formulations containing it, must be able to be effectively stored for appreciable periods of time without exhibiting any significant alteration in the physicochemical characteristics of the active compound (e.g., chemical composition, density, hygroscopicity, and solubility).

[007] The need remains to provide a solid form of Compound (I) that has adequate physical and chemical stability and other drug-related properties suitable for pharmaceutical development. Summary of the descriptive report

[008] In one aspect, the descriptive report provides a crystalline form that is a cocrystal of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]1,2'-dione: F Compound (I), and adipic acid in a 2:1 ratio (herein referred to as “Form A of Compound (I)”).

[009] Those skilled in the art will appreciate that, although a specific tautomer of Compound (I) is shown above, Compound (I) may exist Petition 870250081337, dated 10 / 09 / 2025, page 13 / 64 5 / 47 in multiple tautomeric forms. The descriptive report covers all these tautomeric forms.

[0010] The descriptive report also provides a pharmaceutical composition comprising Compound (I) Form A and at least one pharmaceutically acceptable excipient.

[0011] The descriptive report also provides Compound Form A (I) for use as a medicine, for example, in the prophylaxis or treatment of a PRMT5-mediated disorder.

[0012] The descriptive report also provides the use of Compound Form A (I) in the manufacture of a drug, for example, for the prophylaxis or treatment of a PRMT5-mediated disorder.

[0013] The descriptive report also provides a method for preventing or treating, for example, preventing or treating a PRMT5-mediated disorder, which comprises administering Compound Form A (I).

[0014] Document PCT / EP2022 / 075248 (published as International Publication Leaflet WO2023 / 036974) describes the synthesis of a crystalline form of Compound (I) (herein referred to as “Reference Form 1”). However, as discussed in the Examples below, experimental investigation of its properties has revealed that Reference Form 1 exhibits characteristics that may be detrimental to pharmaceutical development. For example, under ambient conditions, Reference Form 1 exists as a hemihydrate that can be reversibly converted to the anhydrous or monohydrate form by changes in temperature and / or relative humidity.The reversible (de)hydration behavior of Reference Form 1 can result in unpredictable changes in physical properties due to interconversion between distinct forms, consequently affecting storage and manufacturing, and may also create variability in analytical assays that could complicate its development and use as a pharmaceutical active ingredient. Petition 870250081337, dated 10 / 09 / 2025, page 14 / 64 6 / 47

[0015] Compound Form A, as described herein, has a distinct crystalline structure (as determined by XRPD) and, surprisingly, exhibits a combination of characteristics that are attractive in the context of pharmaceutical development. For example, Compound Form A exhibits high thermal stability (melting point -217.6 °C, as determined by DSC); is non-solvated (as determined by DSC and TGA); exhibits low hygroscopic capacity (as determined by DVS); appears to be physically stable (as determined by XRPD analysis after an aqueous fluid paste stability experiment); and appears to have better solubility in a range of biorelevant media compared to Reference Form 1 (as determined by experiments in intestinal and gastric fluid models).

[0016] Compound (I) may exist in other solid forms with alternative counterions, such as acetic acid, 1,5-naphthalenedisulfonic acid, glutaric acid, oxalic acid, propionic acid, camphoric acid, 5-nitroisophthalic acid, 5-chlorsalicylic acid, 3,5-dinitrobenzoic acid, benzoic acid, fumaric acid, sulfuric acid, 2-mesitylenesulfonic acid, gallic acid, 3,5-dihydroxybenzoic acid, or 2,4-dihydroxybenzoic acid. These may exist in crystalline forms that are i) cocrystals of Compound (I) and the counterion; ii) salts of Compound (I); or mixtures thereof. However, Form A of Compound (I) is a crystalline form that appears to be particularly suitable for pharmaceutical development. Brief Description of the Figures

[0017] Figure 1: Powder X-ray diffraction pattern of Compound Form A (I), a physical form of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]1,2'-dione and adipic acid in a 2:1 ratio.

[0018] Figure 2: Superimposed thermogram obtained by differential scanning calorimetry and thermogravimetric analysis of Reference Form 1. Petition 870250081337, dated 10 / 09 / 2025, page 15 / 64 7 / 47

[0019] Figure 3: Superimposed thermogram obtained by differential scanning calorimetry and thermogravimetry of Form A of Compound (I).

[0020] Figure 4: Dynamic vapor sorption isotherm plot of Reference Form 1.

[0021] Figure 5: Dynamic vapor sorption isotherm plot of Compound Form A (I). Detailed Description

[0022] Powder X-ray diffraction analysis can be performed according to standard methods, examples of which can be found in, for example, Kitaigorodsky, AI (1973), Molecular Crystals and Molecules, Academic Press, New York; Bunn, CW (1948), Chemical Crystallography, Clarendon Press, London; or Klug, HP & Alexander, LE (1974), X-ray Diffraction Procedures, John Wiley & Sons, New York.

[0023] It is known in the art that a powder X-ray diffraction pattern can be obtained having one or more measurement errors depending on the measurement conditions (such as equipment, sample preparation, or machine used). In particular, it is generally known that the intensities in a powder X-ray diffraction pattern can oscillate depending on the measurement conditions and sample preparation. For example, one skilled in the art of powder X-ray diffraction will realize that the relative peak intensities can vary according to the orientation of the sample under test and the type and configuration of the instrument used. One skilled in the art will also realize that the position of the reflections can be affected by the precise height at which the sample is placed in the diffractometer and by the zero calibration of the diffractometer. The surface flatness of the sample can also have a small effect.Those versed in the technique of X-ray powder diffraction will also realize that the relative intensity of the peaks can be affected, for example, by grains larger than approximately 30 micrometers and non-unitary aspect ratios, which can affect the analysis of the... Petition 870250081337, dated 10 / 09 / 2025, p. 16 / 64 8 / 47 samples. Furthermore, it should be understood that intensities may oscillate depending on experimental conditions and sample preparation, such as preferred orientation of particles in the sample. The use of automatic or fixed divergence slits will also influence the relative intensity calculations. One skilled in the art can handle such effects when comparing diffraction patterns. Therefore, one skilled in the art will appreciate that the diffraction pattern data presented in the present invention should not be interpreted as absolute and any crystalline form that provides a powder diffraction pattern substantially identical to those disclosed herein falls within the scope of this descriptive report (for more information, see Jenkins, R & Snyder, RL “Introduction to X-Ray Powder Diffractometry” John Wiley & Sons 1996).

[0024] In general, a measurement error of a diffraction angle in a powder X-ray diffractogram is about 5% or less, in particular plus or minus 0.2°2-theta, and such a degree of measurement error should be taken into account when considering the powder X-ray diffraction patterns in Figure 1 and when reading Tables 2 and 3. Furthermore, it should be understood that intensities can oscillate depending on experimental conditions and sample preparation (preferred orientation). The definition of relative intensity is described in Table 1: Table 1. Definition of relative intensity. Percentage of relative intensity Definition 25 to 100 very strong 10 to 25 strong 3 to 10 medium <3 weak

[0025] A powder X-ray diffraction pattern was obtained directly from a sample of Compound (I) Form A, prepared as described herein. From visual analysis of the pattern (Figure 1), it is evident that Compound (I) Form A is highly crystalline. The ten most prominent peaks are shown in Table 2: Petition 870250081337, dated 10 / 09 / 2025, page 17 / 64 9 / 47 Table 2, Ten most prominent peaks in the powder X-ray diffraction pattern of FormaA. 2θ,° Relative intensity 8.9 very strong 14.5 strong 16.9 strong 17.4 strong 19.1 very strong 19.7 very strong 21.2 strong 22.9 very strong 23.7 strong 25.8 strong

[0026] The term “about”, as used herein when referring to any given numerical value, means within ±5% of that value.

[0027] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least one specific peak at (±0.2) 8.9 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least one specific peak at about 8.9 degrees 2-theta when the measurement is made using CuKa radiation.

[0028] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least one specific peak at (±0.2) 19.1 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least one specific peak at about 19.1 degrees 2-theta when the measurement is made using CuKa radiation.

[0029] In one embodiment, the descriptive report provides Compound Form A (I) which has a powder X-ray diffraction pattern containing at least two specific peaks at (±0.2) 8.9 and 19.1 degrees 2-theta when the Petition 870250081337, dated 10 / 09 / 2025, page 18 / 64 10 / 47 measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least two specific peaks at about 8.9 and 19.1 degrees 2-theta when measured using CuKa radiation.

[0030] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least one specific peak selected from (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least one specific peak selected from about 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation.

[0031] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least two specific peaks selected from (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least two specific peaks selected from about 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation.

[0032] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least three specific peaks selected from (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least three specific peaks selected from about 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation.

[0033] In one embodiment, the descriptive report provides Form A Petition 870250081337, dated 10 / 09 / 2025, page 19 / 64 11 / 47 of Compound (I), which has a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Form A of Compound (I), which has a powder X-ray diffraction pattern containing specific peaks at about 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation.

[0034] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation and one, two, three, four, five or six specific peaks selected from (±0.2) 14.5, 16.9, 17.4, 21.2, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing specific peaks at about 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation and one, two, three, four, five or six specific peaks selected from about 14.5, 16.9, 17.4, 21.2, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation.

[0035] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least two peaks selected from (±0.2) 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing at least two peaks selected from about 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation.

[0036] In one embodiment, the descriptive report provides Form A Petition 870250081337, dated 10 / 09 / 2025, page 20 / 64 12 / 47 of Compound (I), which has a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation. In one embodiment, the descriptive report provides Form A of Compound (I), which has a powder X-ray diffraction pattern containing specific peaks at approximately 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation.

[0037] The complete list of XRPD pattern peaks for Compound (I) Form A is shown in Table 3. In one embodiment, the descriptive report provides Compound (I) Form A, which has a powder X-ray diffraction pattern containing the specific peaks substantially as shown in Table 3 when measured using CuKa radiation.

[0038] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation and one, two or three specific peaks selected from (±0.2) 27.0, 28.1 and 29.2 2-theta when the measurement is made using CuKa radiation.In one embodiment, the descriptive report provides Compound Form A (I) which has a powder X-ray diffraction pattern containing specific peaks at about 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation and one, two or three selected specific peaks at about 27.0, 28.1 and 29.2 degrees 2-theta when the measurement is made using CuKa radiation.

[0039] In one embodiment, the descriptive report provides Compound Form A (I), which has a powder X-ray diffraction pattern substantially as shown in Figure 1 when the measurement is made using CuKa radiation.

[0040] In this descriptive report, in cases where the form Petition 870250081337, dated 10 / 09 / 2025, page 21 / 64 13 / 47 crystalline is described as having “a powder X-ray diffraction pattern containing at least one specific peak at (±0.2)…” or “a powder X-ray diffraction pattern containing at least one specific peak at approximately…”, the XRPD of the crystalline form may contain one or more of the 2-theta values ​​shown, for example, one or more of the 2-theta values, 2 or more of the 2-theta values, or 3 or more of the 2-theta values ​​shown. Similar descriptions with reference to different numbers of peaks (such as “…containing at least two specific peaks…” etc.) should be interpreted in the same way.

[0041] Compound Form A (I) was also characterized by differential scanning calorimetry (DSC). One versed in the technique will understand that the value or range of values ​​observed in the DSC thermogram of a specific compound will show variation between batches of different purities. Therefore, while for one compound the range may be small, for others the range may be quite large. In general, a measurement error of a diffraction angle in DSC thermal events is approximately plus or minus 5 °C, and such a degree of measurement error should be taken into account when considering the DSC data included herein, as for Figure 3.

[0042] When heated in a differential scanning calorimeter (conditions as described in the Examples section), Form A of Compound (I) exhibits a melting process with an onset temperature of about 216.6 °C and a peak temperature of about 217.7 °C as illustrated in Figure 3.

[0043] In one embodiment, the descriptive report provides Compound Form A (I), which has a DSC thermogram with an initial melt at 216.6 °C plus or minus 5 °C and a peak at 217.7 °C plus or minus 5 °C. In one embodiment, the descriptive report provides Compound Form A (I) which has a DSC thermogram with an initial melt at about 216.6 °C and a peak at about 217.7 °C. In one embodiment, the descriptive report Petition 870250081337, dated 10 / 09 / 2025, p. 22 / 64 14 / 47 provides Form A of Compound (I) which has a DSC thermogram substantially as shown in Figure 3.

[0044] Thermogravimetric analysis (TGA) (in combination with DSC, as described above) also demonstrates that, in contrast to Reference Form 1 (which, as discussed above, has variable and reversible (de)hydration), Form A of Compound (I) is not solvated, which may provide advantages during storage, manufacturing and pharmaceutical development.

[0045] In one embodiment, the descriptive report provides Compound Form A (I) which has a DSC and TGA superimposed thermogram substantially as shown in Figure 3.

[0046] In one embodiment, the descriptive report provides a crystalline form that is a cocrystal of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]1,2'-dione: F Compound (I), and adipic acid in a 2:1 ratio (Form A of Compound (I)), having at least one of the following: a) a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation; b) a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 Petition 870250081337, dated 10 / 09 / 2025, page 23 / 64 15 / 47 degrees 2-theta when the measurement is made using CuKa radiation; c) a powder X-ray diffraction pattern substantially as shown in Figure 1; d) a DSC thermogram with an initial melting point at 216.6 °C plus or minus 5 °C and a peak at 217.7 °C plus or minus 5 °C; (e) a DSC thermogram and, optionally, a TGA thermogram substantially as shown in Figure 3.

[0047] When it is stated that the present descriptive report refers to a crystalline form, the degree of crystallinity is greater than about 60%. In one embodiment, the degree of crystallinity is greater than about 80%. In one embodiment, the degree of crystallinity is greater than about 90%. In one embodiment, the degree of crystallinity is greater than about 95%. In one embodiment, the degree of crystallinity is greater than about 98%.

[0048] It is desirable that the crystalline form be substantially free of other crystalline forms of Compound (I) (i.e., a crystalline form or forms other than Form A of Compound (I)). Therefore, in one embodiment, the crystalline form contains less than 20%, 15%, 10%, 5%, 3%, or 1% by weight of other crystalline forms of Compound (I). In another embodiment, the crystalline form contains more than 80%, 85%, 90%, 95%, 97%, or 99% by weight of Form A of Compound (I).

[0049] Based on the present experimental data, it is believed that Form A of Compound (I) is a cocrystal of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]-1,2'-dione and adipic acid in a 2:1 ratio, that is, having a stoichiometric ratio of 2:1 of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]-1,2'-dione: adipic acid. Form A of Compound (I) can also be called the cocrystal of Compound (I): hemiadipic acid.

[0050] Without wishing to be limited by theory, cocrystal formation Petition 870250081337, dated 10 / 09 / 2025, p. 24 / 64 16 / 47 results from situations where an acid or base “coformer” is a solid at room temperature and there is no or only partial proton transfer between the free compound and such acid or base coformer. Consequently, a cocrystal of the coformer and the free compound results, rather than a salt. The definition of the acid or base coformer being a solid at room temperature is intended to distinguish cocrystals from solvates. It is accepted that proton transfer is in fact a continuum and can change with temperature, and therefore the point at which a cocrystal is best described as a salt can be somewhat subjective. However, as mentioned above, based on all the experimental evidence present, it is believed that Form A of Compound (I) is a cocrystal.

[0051] In one embodiment, Form A of the Compound (I) obtainable by any of the methods disclosed herein. In one embodiment, Form A of the Compound (I) obtainable by the method of Example 1, Method A, is provided. In one embodiment, Form A of the Compound (I) obtainable by the method of Example 1, Method B, is provided. In one embodiment, Form A of the Compound (I) obtainable by the method of Example 1, Method C, is provided.

[0052] Compound Form A (I) can be further characterized by additional techniques well known to those skilled in the art, such as single-crystal X-ray diffraction (e.g., to assess proton position, bond lengths or bond angles), solid-state 1H NMR (to assess, for example, C or N chemical shifts) or spectroscopic techniques (to measure, for example, OH or NH signals and IR peak shifts resulting from hydrogen bonding).

[0053] Form A of Compound (I) can be prepared as described in the Examples of the present invention. The crystallization of the desired Form A of Compound (I) can be aided by seeding with crystals of the desired shape. The seed crystals can be obtained using one of the Petition 870250081337, dated 10 / 09 / 2025, page 25 / 64 17 / 47 methods described in the Examples, such as Method B. The use of seeding is particularly advantageous in large-scale manufacturing. Medical uses

[0054] As described above, Compound (I) is a PRMT5 inhibitor and, in particular, Compound (I) is a synergistic PRMT5 inhibitor with MTA. Therefore, Form A of Compound (I) is expected to be useful as a medicament, such as in the prophylaxis or treatment of a PRMT5-mediated disorder, i.e., a disorder in which PRMT5 inhibition provides a prophylactic or therapeutic effect.

[0055] As used herein, the term “prophylaxis” is intended to have its normal meaning and include primary prophylaxis to prevent the development of the disease or condition, and secondary prophylaxis whereby the disease or condition has already developed and the individual is temporarily or permanently protected against exacerbation or worsening of the disease or condition, or the development of new symptoms associated with the disease or condition. The terms “prophylactic,” “prevent,” and “prevention” are used synonymously with “prophylaxis.”

[0056] As used herein, the term “treatment” is intended to have its normal meaning of dealing with a disease or condition in order to relieve wholly or partially one, some, or all of its symptoms in an individual, or to correct or compensate for the underlying pathology. The terms “treatment” and “to treat” are used synonymously with “therapy”.

[0057] An individual will typically be an individual in need of prophylaxis or treatment according to the descriptive report. In one embodiment, the individual is a human being.

[0058] In one embodiment, the descriptive report provides Form A of Compound (I) for use as a medicament.

[0059] In one embodiment, the descriptive report provides Compound Form A (I) for use in the prophylaxis or treatment of a disorder. Petition 870250081337, dated 10 / 09 / 2025, page 26 / 64 18 / 47 mediated by PRMT5 (e.g., cancer). In one embodiment, the descriptive report provides Compound Form (I) for use in the prophylaxis of a PRMT5-mediated disorder (e.g., cancer). In another embodiment, the descriptive report provides Compound Form (I) for use in the treatment of a PRMT5-mediated disorder (e.g., cancer).

[0060] In one embodiment, the descriptive report provides the use of Compound Form A (I) in the manufacture of a drug product.

[0061] In one embodiment, the descriptive report provides the use of Compound Form A in the manufacture of a medicament for the prophylaxis or treatment of a PRMT5-mediated disorder (e.g., cancer). In one embodiment, the descriptive report provides the use of Compound Form A in the manufacture of a medicament for the prophylaxis of a PRMT5-mediated disorder (e.g., cancer). In one embodiment, the descriptive report provides the use of Compound Form A in the manufacture of a medicament for the treatment of a PRMT5-mediated disorder (e.g., cancer).

[0062] In one embodiment, the descriptive report provides a method for preventing or treating a PRMT5-mediated disorder (e.g., cancer), which comprises administering Compound Form A (I). In one embodiment, the descriptive report provides a method for preventing a PRMT5-mediated disorder (e.g., cancer), which comprises administering Compound Form A (I). In one embodiment, the descriptive report provides a method for treating a PRMT5-mediated disorder (e.g., cancer).

[0063] In one embodiment, the PRMT5-mediated disorder is cancer. In one embodiment, the cancer is an MTAP deletion cancer, that is, a cancer in which the MTAP gene has been deleted. In one embodiment, the cancer is a CDKN2A and MTAP deletion cancer, that is, a cancer in which both the CDKN2A and MTAP genes are deleted. Petition 870250081337, dated 10 / 09 / 2025, page 27 / 64 19 / 47

[0064] In one embodiment, the cancer is selected from among gastric, pancreatic, colorectal, uterine, bile duct, stomach, bladder, cervical, testicular germ cell, lung (e.g., non-small cell lung cancer), multiple myeloma, lymphoma (e.g., diffuse large B-cell lymphoma or Hodgkin lymphoma), rhabdomyosarcoma, and cutaneous squamous cell carcinoma.

[0065] In one embodiment, the cancer is selected from among gastric, lung (e.g., non-small cell lung cancer) and lymphoma (e.g., diffuse large B-cell lymphoma or Hodgkin lymphoma).

[0066] In one embodiment, the cancer is non-small cell lung cancer. In one embodiment, the cancer is diffuse large B-cell lymphoma. In one embodiment, the cancer is Hodgkin's lymphoma. Combined therapy

[0067] Compound Form A (I) can be administered in conjunction with other compounds used to treat the above conditions. In one embodiment, a combination therapy is provided comprising Compound Form A (I) and a second active ingredient.

[0068] Compound Form A (I) and a second active ingredient may be administered simultaneously, sequentially or in a mixture, for the treatment of one or more of the conditions mentioned above. Such a combination may be used in combination with one or more additional active ingredients. Pharmaceutical compositions

[0069] For use in prophylaxis or therapy, Compound Form A (I) will typically be administered as a pharmaceutical composition. Therefore, in one embodiment, the descriptive report provides a pharmaceutical composition comprising Compound Form A (I) and at least one pharmaceutically acceptable excipient. Petition 870250081337, dated 10 / 09 / 2025, page 28 / 64 20 / 47

[0070] In one embodiment, the descriptive report provides a pharmaceutical composition comprising Compound Form A (I) and at least one excipient that is pharmaceutically acceptable for use as a medicament.

[0071] In one embodiment, the descriptive report provides a pharmaceutical composition comprising Form A of Compound (I) and at least one pharmaceutically acceptable excipient for use in the prophylaxis or treatment of a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer). In one embodiment, the descriptive report provides a pharmaceutical composition comprising Form A of Compound (I) and at least one pharmaceutically acceptable excipient for use in the prophylaxis of a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer). In one embodiment, the descriptive report provides a pharmaceutical composition comprising Form A of Compound (I) and at least one pharmaceutically acceptable excipient for use in the treatment of a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer).

[0072] In one embodiment, the descriptive report provides the use of a pharmaceutical composition comprising Compound Form (I) and at least one pharmaceutically acceptable excipient, in the manufacture of a medicament.

[0073] In one embodiment, the descriptive report provides the use of a pharmaceutical composition comprising Compound Form A and at least one pharmaceutically acceptable excipient, in the manufacture of a medicament for the prophylaxis or treatment of a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer). In one embodiment, the descriptive report provides the use of a pharmaceutical composition comprising Compound Form A and at least one pharmaceutically acceptable excipient, in the manufacture of a medicament Petition 870250081337, dated 10 / 09 / 2025, page 29 / 64 21 / 47 for the prophylaxis of a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer). In one embodiment, the descriptive report provides the use of a pharmaceutical composition comprising Form A of Compound (I) and at least one pharmaceutically acceptable excipient, in the manufacture of a medicament for the treatment of a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer).

[0074] In one embodiment, the descriptive report provides a method for preventing or treating a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer), which comprises administering a pharmaceutical composition comprising Compound Form A and at least one pharmaceutically acceptable excipient. In one embodiment, the descriptive report provides a method for preventing a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer), which comprises administering a pharmaceutical composition comprising Compound Form A and at least one pharmaceutically acceptable excipient. In one embodiment, the descriptive report provides a method for treating a PRMT5-mediated disorder, such as the disorders disclosed herein (e.g., cancer), which comprises administering a pharmaceutical composition comprising Compound Form A and at least one pharmaceutically acceptable excipient. Administration

[0075] Compound Form A will normally be administered in the form of a pharmaceutical composition comprising Compound Form A in a pharmaceutically acceptable dosage form via the oral, parenteral, intravenous, intramuscular, subcutaneous or other injectable, buccal, rectal, vaginal, transdermal and / or nasal and / or inhalation routes. Depending on the disorder and the patient to be treated and the route of administration, the compositions may be administered in varying doses. Petition 870250081337, dated 10 / 09 / 2025, page 30 / 64 22 / 47 In one embodiment, Form A of Compound (I) or a pharmaceutical composition comprising Form A of Compound (I) and at least one pharmaceutically acceptable excipient is administered orally.

[0076] Dosage forms suitable for oral use form an aspect of the descriptive report. In one embodiment, the descriptive report provides a solid oral dosage form comprising Compound Form A or a pharmaceutical composition comprising Compound Form A and at least one pharmaceutically acceptable excipient. In one embodiment, the solid oral dosage form is a tablet.

[0077] The compositions in the descriptive report can be obtained by conventional procedures using conventional pharmaceutical excipients well known in the art. Thus, compositions intended for oral use may contain, for example, one or more coloring agents, sweeteners, flavorings and / or preservatives.

[0078] Pharmaceutically acceptable excipients suitable for a tablet formulation include, for example, inert diluents; granulating and disintegrating agents; binding agents; and lubricating agents. Tablet formulations may be uncoated or coated using conventional coating agents and procedures well known in the art.

[0079] For additional information on formulations, the reader is referred to Chapter 25.2 of Volume 5 of Comprehensive Medicinal Chemistry (Corwin Hansch; Chairman of the Editorial Board), Pergamon Press 1990.

[0080] The amount of active ingredient (i.e., Compound (I) Form A) that is combined with one or more excipients to produce a single dosage form will necessarily vary depending on the host being treated and the specific route of administration.

[0081] The appropriate daily doses of Compound Form A (I) in Petition 870250081337, dated 10 / 09 / 2025, page 31 / 64 23 / 47 prophylactic or therapeutic treatment doses in humans are approximately 0.0001 to 100 mg / kg of body weight.

[0082] For additional information on Routes of Administration and Dosage Regimens, the reader is referred to Chapter 25.3 in Volume 5 of Comprehensive Medicinal Chemistry (Corwin Hansch; Chairman of the Editorial Board), Pergamon Press 1990.

[0083] The descriptive report may be further illustrated by the following non-limiting examples. Examples

[0084] In general: (i) the operations were performed at ambient temperature, i.e., in the range of 17 to 25 °C and under an atmosphere of an inert gas, such as nitrogen, unless otherwise indicated; (ii) Evaporations were carried out by rotary evaporation or using Genevac equipment or a Biotage v10 vacuum evaporator and processing procedures were carried out after the removal of residual solids by filtration; (iii) flash chromatography purifications were performed on an automated Teledyne Isco CombiFlash® Rf instrument or Teledyne Isco CombiFlash® Companion® using pre-packed RediSep Rf Gold™ silica columns (20-40 μm, spherical particles), GraceResolv™ cartridges (Davisil® silica) or Silicycle cartridges (40 to 63 μm); (iv) Preparatory reversed-phase HPLC was performed on an Agilent 1290 Infinity II preparatory system equipped with an SQ MS detector (ESI / APCI multimode source), with a Waters CSH C18 OBD column (5 microns silica, 30 mm diameter, 100 mm length, 50 mL / min flow rate) using water mixtures with decreasing polarity (containing 0.1 to 0.3% aqueous ammonia) or water (containing 0.1% formic acid) and Petition 870250081337, dated 10 / 09 / 2025, page 32 / 64 24 / 47 acetonitrile as eluents. Preparatory SFC purification was performed on a Sepiatec P100 SFC system or Waters Prep 100 SFC system equipped with a QDa MS detector, using the chromatographic conditions as detailed in the corresponding experimental data; (v) incomes, when present, are not necessarily the maximum attainable; (vi) In general, NMR chemical shift values ​​were measured on the delta scale [proton magnetic resonance spectra were determined using a Bruker Avance 400 instrument (400 MHz)]; measurements were made at room temperature unless otherwise specified; The following abbreviations were used: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; dd, doublet of doublets; ddd, doublet of doublet of doublet; dt, doublet of triplets; bs (broad signal), broad signal; (vii) In general, the compounds were also characterized by liquid chromatography-based mass spectrometry (LCMS or UPLC); reversed-phase C18 silica was used with a flow rate of 1 mL / min and detection was by electrospray mass spectrometry and UV absorbance recording a wavelength range of 220 to 320 nm. Analytical UPLC was performed on reversed-phase CSH C18 silica, using a Waters Acquity UPLC CSH C18 column with dimensions of 2.1 x 50 mm and a particle size of 1.7 microns. Gradient analysis was employed using mixtures with decreasing polarities as eluents, for example, mixtures with decreasing polarities of water (containing 0.1% formic acid or 0.1% ammonia) as solvent A and acetonitrile as solvent B.A typical 2-minute UPLC analytical method would employ a solvent gradient over 1.3 min, at approximately 1 mL / min, from a 97:3 mixture of solvents A and B, respectively, to a 3:97 mixture of solvents A and B. The reported molecular ion corresponds to [M+H]+, minus. Petition 870250081337, dated 10 / 09 / 2025, p. 33 / 64 25 / 47 that is specified otherwise; for molecules with multiple isotopic standards (Br, Cl, etc.), the reported value is that obtained for the lowest isotopic mass, unless otherwise specified; (viii) Intermediate purity was assessed by thin layer chromatography, mass spectrometry, HPLC (high performance liquid chromatography) and / or NMR analysis. Preparation of the reference form 1

[0085] A synthesis of Compound (I) is described in document PCT / EP2022 / 075248 (published as International Publication Leaflet WO2023 / 036974), the contents of which are incorporated by reference for the purpose of describing Compound (I) and its synthesis. The compounds described below were named using Chemdraw version 20.0.2.51 and the synthetic methods described herein are given for illustrative purposes only and are not limiting. AQ Intermediate: tert-butyl (6-chloro-5-fluoropyridin-3-yl)carbamate

[0086] To 5-bromo-2-chloro-3-fluoropyridine (100 g, 475.22 mmol) in dioxane (1 L) was added tert-butyl carbamate (61.20 g, 522.74 mmol) and cesium carbonate (310.00 g, 950.43 mmol). The solution was degassed under vacuum and purged with an inert nitrogen atmosphere for 5 minutes, followed by the addition of tris(dibenzylideneacetone)dipalladium(0) (13.06 g, 14.26 mmol) and (9,9-dimethyl9H-xanthene-4,5-di-yl)bis(diphenylphosphane) (Xantphos) (11.00 g, 19.01 mmol). The reaction mixture was heated to 85 °C under nitrogen for 16 hours and then cooled to room temperature. The solid was filtered and washed with excess dioxane. The solvent was removed under vacuum, obtaining the crude title compound (179 g, 153%) as a dark orange gum that solidified on stand. The crude gum was used directly in the next step without further purification. Ή NMR (400 MHz, DMSO-d6, 30 °C) 1,49 (9H, s), Petition 870250081337, dated 10 / 09 / 2025, p. 34 / 64 26 / 47 7.98 (1H, dd), 8.29 (1H, d), 9.98 (1H, s); m / z MH+247. AR Intermediate: 6-Chloro-5-fluoropyridin-3-amineH2Nx / \ / F

[0087] 4M HCl in 1,4-dioxane (137 mL, 547.3 mmol) was added in a portion to a solution of tert-butyl (6-chloro-5-fluoropyridin-3-yl)carbamate (36 g, 109.5 mmol) in 1,4-dioxane (20 mL) at 20 °C. The resulting suspension was stirred at 20 °C for 3 days. The reaction mixture was diluted with water (250 mL) and EtOAc (100 mL). The organic phase was separated and extracted with 2M HCl (3 x 100 mL) until no product remained in the organic phase. The combined aqueous phases were stirred and cooled to 0 °C in an ice bath. The reaction mixture was made basic to pH 14 with 50% NaOH solution. The reaction mixture was then extracted with EtOAc (2 x 250 mL), the combined organics were washed with saturated brine (50 mL), dried with MgSO4, filtered, and the solvent was removed under vacuum to yield the title compound (12.4 g, 77%) as a brown solid. Used directly in the next step without further purification.H NMR (400 MHz, CDCl3, 27 °C) 3.88 (s, 2H), 6.80 (dd, J = 9.6, 2.5 Hz, 1H), 7.68 (d, J = 2.5 Hz, 1H). AS Intermediate: 2-bromo-6-chloro-5H-fluoropyridin-3-amine

[0088] 6-chloro-5-fluoropyridin-3-amine (56.8 g, 379.3 mmol) in MeCN (250 mL) was cooled to 5 °C and a solution of NBS (67.50 g, 379.3 mmol) in MeCN (500 mL) was added over 15 minutes. The reaction mixture was heated to room temperature and stirred for 45 minutes. Water (2 L) was added and the reaction mixture was stirred for 30 minutes. The resulting solid was filtered and washed with water (400 mL). The Petition 870250081337, dated 10 / 09 / 2025, p. 35 / 64 27 / 47 solid was vacuum dried to yield the title compound (76 g, 89%) as a brown solid. Ή NMR (400 MHz, DMSO-d6, 30 °C) 6.01 (2H, s), 7.12 (1H,d); m / zMH+225. AT Intermediate: 5-chloro-6-fluoro-1H-pyrrolo[3,2-b]pyridine-2-carboxylic acid Hc HO

[0089] Palladium acetate (3.35 g, 14.93 mmol), triphenylphosphine (3.92 g, 14.93 mmol), 2-bromo-6-chloro-5-fluoropyridin-3-amine (18.0 g, 74.65 mmol), and pyruvic acid (15.57 mL, 224 mmol) were placed in a flask with 1,4-dioxane (88 mL). Triethylamine (45.80 mL, 328.5 mmol) was added, and the reaction was heated to 100 °C for 2.5 hours under nitrogen. The reaction mixture was cooled to room temperature and filtered to remove unwanted solids. The filtrate was diluted with 2M NaOH (200 mL), and MTBE (200 mL) was added. The reaction mixture was then vigorously stirred and separated. The organic phase was washed with 2M NaOH (100 mL). The combined basic aqueous phases were carefully acidified with concentrated (aqueous) HCl, and a brown precipitate was collected by filtration and dried. The dark brown solid was suspended in MeOH (90 mL) and stirred for 2 hours at room temperature.The solid was filtered and vacuum dried to yield the title compound (14.60 g, 91%) as a beige solid. 1H NMR (400 MHz, DMSO-d6, 30 °C) 7.16 (1H, dd), 7.84 (1H, dd), 12.36 (1H, s), 13.46 (1H, s); m / z MH+214. AU Intermediate: 5-chloro-6-fluoro-1H-pyrrolo[3,2-b]pyridine-2-carboxylate methyl

[0090] Sulfuric acid (3.08 mL, 57.83 mmol) was added dropwise to Petition 870250081337, dated 10 / 09 / 2025, p. 36 / 64 28 / 47 dropwise to 5-chloro-6-fluoro-1H-pyrrolo[3,2-b]pyridine-2-carboxylic acid (14.60 g, 57.83 mmol) in MeOH (113 mL) at room temperature. The reaction mixture was stirred under reflux for 18 hours. The reaction mixture was allowed to cool naturally and the solvent was removed under vacuum. Saturated NaHCO3 (400 mL) was carefully added to the residue and the resulting precipitate was removed by filtration, washed with water and dried under vacuum to yield the title compound (14.20 g, 107%) as a brown solid. Ή NMR (400 MHz, DMSO-d6, 30 °C) 3.91 (3H, s), 7.24 (1H, dd), 7.88 (1H, dd), 12.56 (1H, s); m / z MH+229. AV Intermediate: 5-chloro-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)-1Hpyrrolo[3,2-b]pyridine-2-carboxylate methyl WITHOUT —o THE·

[0091] Potassium bis(trimethylsilyl)amide (1M in THF) (101 mL, 100.9 mmol) was added dropwise over 15 minutes to a solution of methyl 5-chloro-6-fluoro-1H-pyrrolo[3,2-b]pyridine-2-carboxylate (21.74 g, 77.60 mmol) and (2-(chloromethoxy)ethyl)trimethylsilane (18.83 mL, 100.9 mmol) in THF (419 mL) at 5 °C under nitrogen. The reaction mixture was stirred at 5 °C for 30 minutes. Potassium bis(trimethylsilyl)amide (1M in THF) (15.52 mL, 15.52 mmol) was added and the reaction mixture was stirred at 5 °C for a further 30 minutes. (2-(chloromethoxy)ethyl)trimethylsilane (1.88 mL, 10.09 mmol) was added and stirred at 5 °C for a further 15 minutes. The reaction mixture was rapidly cooled with saturated NH4Q (400 mL) and diluted with EtOAc (400 mL). The aqueous phase was extracted again with EtOAc (250 mL). The combined organic phases were dried with MgSO4, filtered, and the solvent was removed under vacuum. The crude material was suspended in heptane (450 mL) and stirred for 5 minutes.The unwanted solid was removed by filtration and washed with heptane (50 mL). The solvent was removed under vacuum to produce... Petition 870250081337, dated 10 / 09 / 2025, page 37 / 64 29 / 47 the title compound (32.50 g, 117%) as a brown gum that solidified on rest. The gum was used directly in the next step without further purification. Ή NMR (400 MHz, DMSO-d6, 30 °C) -0.13 (9H, s), 0.70 - 0.80 (2H, m), 3.38 - 3.51 (2H, m), 3.89 (3H, s), 5.95 (2H, s), 7.41 (1H, d), 8.40 - 8.54 (1H, m); m / z MH+359. AW Intermediate: (5-chloro-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)-1-Hpyrrolo[3,2-b]pyridin-2-yl)methanol

[0092] Diisobutylaluminum hydride (1 M in toluene) (170 mL, 170.42 mmol) was added dropwise to a stirred solution of 5-chloro-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-pyrrolo[3,2-b]pyridine-2-carboxylate (27.80 g, 77.47 mmol) in DCM (333 mL) at 5 °C for 15 minutes. The reaction mixture was stirred at room temperature for 30 minutes. The reaction mixture was carefully poured into 2 M NaOH (500 mL), diluted with DCM (500 mL), and stirred for 1 hour. The organic phase was separated, and the aqueous phase was extracted with DCM (2 x 200 mL). The combined organics were dried with MgSO4, filtered, and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution from 0 to 40% EtOAc in heptane. The pure fractions were evaporated to dryness in order to yield the title compound (17.60 g, 68%) as a pale orange oil that solidified on stand.>H NMR (400 MHz, DMSO-d6, 30 °C) -0.10 (9H, s), 0.75 - 0.83 (2H, m), 3.36 - 3.56 (2H, m), 4.72 (2H, d), 5.50 (1H, t), 5.60 (2H, s), 6.57 (1H, d), 8.24 (1H, dd); m / z MH+331. Intermediate AX: 5-chloro-2-(chloromethyl)-6-fluoro-1-((2(trimethylsilyl)ethoxy)methyl)-1H-pyrrolo[3,2-b]pyridine Petition 870250081337, dated 10 / 09 / 2025, p. 38 / 64 30 / 47 SEM \cci mt y

[0093] Thionyl chloride (13.2 mL, 181.4 mmol) was added dropwise to (5-chloro-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)-1-Hpyrrolo[3,2-b]pyridin-2-yl)methanol (20.0 g, 60.45 mmol) in DCM (200 mL) at room temperature. The reaction mixture was stirred at room temperature for 1 hour. Saturated NaHCO3 (500 mL) was then added slowly. Once gas emission ceased, the phases were separated and the aqueous phase was extracted again with DCM (300 mL). The organic phases were combined, washed with brine (200 mL), passed through a phase separation filter paper, and the solvent was removed under vacuum to yield the title compound (19.2 g, 91%) as a brown crystalline solid. Ή NMR (400 MHz, DMSO-d6, 27 °C) -0.10 (9H, s), 0.75 - 0.9 (2H, m), 3.43 - 3.53 (2H, m), 5.07 (2H, s), 5.66 (2H, s), 6.7 - 6.9 (1H, m), 8.32 (1H, dd); WzMH+349. AA Intermediate: 2-(2-Bromo-4-fluorophenyl)methyl acetate F THE

[0094] Thionyl chloride (31.3 mL, 429.1 mmol) was carefully added dropwise to 2-(2-bromo-4-fluorophenyl)acetic acid (CAS No. 61150-59-2) (100 g, 429.1 mmol) in MeOH (400 mL) at room temperature. The reaction mixture was stirred at 60 °C for 4 hours, cooled, and the solvent was removed under vacuum. The residue was partitioned between EtOAc (250 mL) and saturated NaHCO3 (200 mL). The organic phase was washed with water (100 mL), brine (100 mL), passed through a phase separation filter paper, and the solvent was removed under vacuum to yield the title compound (105 g, 99%) as a colorless oil. ¹H NMR (400 MHz, DMSO-d6, 30 Petition 870250081337, dated 10 / 09 / 2025, p. 39 / 64 31 / 47 °C) 3.64 (3H, s), 3.83 (2H, s), 7.25 (1H, td), 7.48 (1H, dd), 7.58 (1H, dd)); m / z MH+not observed. Intermediate AB: methyl 5-fluoro-2-(2-methoxy-2-oxoethyl)benzoate

[0095] Methyl 2-(2-bromo-4-fluorophenyl)acetate (45.0 g, 182.14 mmol) and triethylamine (27.90 mL, 200.35 mmol) were placed in a steel pressure vessel with MeOH (300 mL). [1,1'Bis(diphenylphosphino)ferrocene]dichloropalladium(II) (dichloromethane complex) (4.46 g, 5.46 mmol) was added and the vessel was sealed. The vessel was purged with carbon monoxide and then charged to 7 bar with carbon monoxide. The pressure vessel was heated to 100 °C and stirred for 2 hours. The reaction mixture was allowed to cool naturally, vented, and filtered to remove the catalyst. The solvent was removed under vacuum and the residue was dissolved in EtOAc (250 mL), washed with water (2 x 200 mL) and brine (100 mL). The organic phase was passed through a phase separation filter paper and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution of EtOAc from 0 to 50% in heptane.The pure fractions were evaporated to dryness to yield the title compound (38.40 g, 93%) as a pale yellow oil. 1H NMR (400 MHz, DMSO-d6, 30 °C) 3.60 (3H, s), 3.80 (3H, s), 3.99 (2H, s), 7.42 - 7.49 (2H, m), 7.66 (1H, ddd); m / z MH+227. Intermediate AC:rac-m ethyl-2-(1-bromo-2-methoxy-2-oxoethyl)-5-fluorobenzoate Petition 870250081337, dated 10 / 09 / 2025, p. 40 / 64 32 / 47

[0096] Methyl 5-fluoro-2-(2-methoxy-2-oxoethyl)benzoate (47.0 g, 207.8 mmol) was dissolved in chloroform (450 mL). 1-bromopyrrolidine-2,5-dione (55.5 g, 311 mmol) was added followed by 2,2'-azobis(2-methylpropionitrile) (3.41 g, 20.8 mmol) and the reaction mixture was stirred under reflux for 72 hours. The reaction mixture was cooled and washed with water (2 x 250 mL), brine (100 mL), passed through a phase separation filter paper and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution from 0 to 40% EtOAc in heptane. The pure fractions were evaporated to dryness to yield the title compound (50.50 g, 80%) as a colorless solid. Ή NMR (400 MHz, DMSO-d6, 30 °C) 3.71 (3H, s), 3.86 (3H, s), 6.51 (1H, s), 7.56 (1H, td), 7.66 (1H, dd), 7.81 (1H, dd); m / z MH+ not observed. AD Intermediate: rac- 5-fluoro-2-(4-methoxybenzyl)-3-oxoisoindoline-1-carboxylate methyl

[0097] 4-methoxybenzylamine (23.5 g, 171 mmol) was placed in a flask with MeCN (300 mL) and sodium bicarbonate (23.9 g, 285 mmol) was added. Methyl rac-2-(1-bromo-2-methoxy-2-oxoethyl)-5-fluorobenzoate (43.5 g, 142 mmol), dissolved in MeCN (100 mL), was added slowly via a dropper funnel as the reaction mixture was brought to 80 °C. The reaction mixture was stirred at 80 °C for 3 hours. The reaction mixture was allowed to cool naturally, and most of the residue was removed. Petition 870250081337, dated 10 / 09 / 2025, page 41 / 64 33 / 47 part of the MeCN was vacuum-sealed and the residue was partitioned between EtOAc (400 mL) and water (400 mL). The aqueous phase was extracted again with EtOAc (100 mL), the organics were combined and washed with brine (50 mL). The organic phase was passed through a phase separation filter paper and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution of EtOAc from 0 to 50% in heptane. The pure fractions were evaporated to dryness to yield the title compound (45.3 g, 96%) as a pale yellow oil. H NMR (400 MHz, DMSO-d6, 30 °C) 3.69 (3H, s), 3.73 (3H, s), 4.31 (1H, d), 5.04 (1H, d), 5.18 (1H, s), 6.87 - 6.94 (2H, m), 7.17 - 7.24 (2H, m), 7.50 (1H, dd), 7.57 (1H, dd), 7.62 (1H, dd); m / z MH+330. AE Intermediate: rac-1-allyl-5-fluoro-2-(4-methoxybenzyl)-3-oxoisoindoline-1-carboxylate methyl

[0098] rac - 5-fluoro-2-(4-methoxybenzyl)-3-oxoisoindoline-1-carboxylate methyl (24.0 g, 72.9 mmol), allyl acetate (11.8 mL, 109 mmol), tris(dibenzylideneacetone)dipalladium(0) (1.67 g, 1.82 mmol) and N,Nf((1R,2R)-cyclohexane-1,2-di-yl)bis(2-(diphenylphosphanoyl)benzamide) (2.52 g, 3.64 mmol) were stirred in THF (400 mL) at 5 °C under nitrogen. 1,1,3,3-tetramethylguanidine (13.7 mL, 109 mmol) was then added dropwise. The reaction mixture was stirred at 5 °C for 5 minutes. The THF was removed under vacuum. The reaction mixture was partitioned between EtOAc (400 mL) and water (400 mL), and the organic phase was passed through a phase-separation filter paper. The solvent was removed under vacuum to produce an orange oil. The crude product was purified by flash chromatography on silica. Petition 870250081337, dated 10 / 09 / 2025, page 42 / 64 34 / 47 gradient elution of EtOAc from 0 to 50% in heptane. The pure fractions were evaporated to dryness to yield the title compound (25.8 g, 96%) as a solid cream. 1H NMR (400 MHz, DMSO-d6, 30 °C) 3.04 - 3.20 (2H, m), 3.26 (3H, s), 3.73 (3H, s), 4.52 (1H, d), 4.71 (1H, d), 4.74 - 4.94 (3H, m), 6.82 - 6.96 (2H, m), 7.28 - 7.39 (2H, m), 7.45 - 7.58 (2H, m), 7.63 (1H, dd); m / z MH+370. AF Intermediate: (S)-1-allyl-5-fluoro-2-(4-methoxybenzyl)-3-oxoisoindoline-1-carboxylate methyl

[0099] rac-1-allyl-5-fluoro-2-(4-methoxybenzyl)-3-oxoisoindoline-1-carboxylate methyl (-70:30 in favor of the desired (S) enantiomer) (25.8 g, 69.7 mmol) was purified by SFC chromatography (Column: Phenomenex C1, 30 x 250 mm, 5 microns, mobile phase: 10% IPA + 0.1% DEA / 90% scCO2, flow rate: 90 mL / min, BPR: 120 bar, column temperature: 40 °C, UV max 210 nm). The pure fractions were evaporated to dryness to yield the title compound (15.1 g, 56%) as a white solid. 'H NMR (400 MHz, DMSO-d6, 30 °C) 3.04 - 3.20 (2H, m), 3.26 (3H, s), 3.73 (3H, s), 4.52 (1H, d), 4.71 (1H, d), 4.74 - 4.94 (3H, m), 6.82 - 6.96 (2H, m), 7.28 - 7.39 (2H, m), 7.45 - 7.58 (2H, m), 7.63 (1H, dd); m / z MH+370.(Presumed stereochemical assignment of this intermediate based on the biological activity of bioactive compounds made using this enantiomer of the intermediate (compared to those made using the other enantiomer), along with X-ray structural evidence that the S enantiomer is preferentially and more active than the R enantiomer). Petition 870250081337, dated 10 / 09 / 2025, page 43 / 64 35 / 47 Intermediate AI: (S)-l-allyl-5-fluoro-3-oxoisoindoline-l-carboxylate methyl

[00100] (S)-1-allyl-5-fluoro-2-(4-methoxybenzyl)-3-oxoisoindoline-1-carboxylate methyl (20.0 g, 54.1 mmol) was placed in a flask with MeCN (200 mL) and water (100 mL). Ammonium cerium(IV) nitrate (74.2 g, 135 mmol) was added and the reaction mixture was stirred at room temperature for 30 min. The MeCN was removed under vacuum and the reaction mixture was partitioned between DCM (400 mL) and water (250 mL). The aqueous phase was extracted with DCM (200 mL). The organic phases were combined, washed with brine (100 mL), passed through a phase separation filter paper, and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution of EtOAc from 0 to 50% in heptane. The pure fractions were evaporated to dryness to yield the title compound (12.5 g, 93%) as a creamy crystalline solid.H NMR (400 MHz, DMSO-d6, 27 °C) 2.79 (1H, dd), 2.94 (1H, dd), 3.68 (3H, s), 4.93 - 5.15 (2H, m), 5.35 - 5.57 (1H, m), 7.37 - 7.46 (1H, m), 7.50 (1H, ddd), 7.63 - 7.79 (1H, m), 9.32 (1H, s); m / z MH+250. BQ Intermediate: (5)-1-allyl-2-((5-chloro-6-fluoro-1-((2(trimethylsilyl)ethoxy)methyl)-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl)-5-fluoro-3-oxoisoindoline-1-carboxylate methyl Petition 870250081337, dated 10 / 09 / 2025, pp. 44 / 64 36 / 47

[00101] Methyl (5)-1-allyl-5-fluoro-3-oxoisoindoline-1-carboxylate (11.80 g, 47.34 mmol) and 5-chloro-2-(chloromethyl)-6-fluoro-1-((2(trimethylsilyl)ethoxy)methyl)-1H-pyrrolo[3,2-b]pyridine (16.9 g, 48.3 mmol) were placed in a flask with dry DMF (60 mL). Cesium carbonate (38.60 g, 118.4 mmol) was added and the reaction mixture was stirred at 60 °C for 2 hours. The reaction mixture was cooled and partitioned between water (300 mL) and EtOAc (300 mL). The aqueous phase was extracted again with EtOAc (200 mL). The organic phases were combined, washed with water (3 x 200 mL), brine (200 mL), passed through a phase separation filter paper, and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution of EtOAc from 0 to 100% in heptane. The pure fractions were evaporated to dryness to yield the title compound (22.2 g, 83%) as a yellow gum that slowly solidified / crystallized to give a yellow solid.

[00102] H NMR (400 MHz, DMSO-d6, 27 °C) -0.09 (9H, s), 0.79 - 0.88 (2H, m), 3.03 (3H, s), 3.16 - 3.29 (2H, m), 3.46 - 3.60 (2H, m), 4.73 (1H, d), 4.89 (1H, dd), 4.94 - 5.10 (2H, m), 5.26 (1H, d), 5.59 (1H, d), 5.68 (1H, d), 6.76 (1H, s), 7.49 - 7.56 (1H, m), 7.58 - 7.68 (2H, m), 8.25 (1H, dd); m / z MH+562. Intermediate BR: (^)-1-allyl-2-((5-((tert-butoxycarbonyl)amino)-6-fluoro-1((2-(trimethylsilyl)ethoxy)methyl)-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl)-5-fluoro-3oxoisoindoline-1-carboxylate methyl Petition 870250081337, dated 10 / 09 / 2025, p. 45 / 64 37 / 47

[00103] (5)-1-allyl-2-((5-chloro-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)1H-pyrrolo[3,2-b]pyridin-2-yl)methyl)-5-fluoro-3-oxoisoindoline-1-carboxylate methyl (15 g, 26.69 mmol), cesium carbonate (21.74 g, 66.72 mmol), BrettPhos Pd G3 (2.42 g, 2.67 mmol), dicyclohexyl(2',4',6'-triisopropyl-3,6-dimethoxy-[1,1'-biphenyl]-2-yl)phosphane (1.43 g, 2.67 mmol) and tert-butyl carbamate (6.25 g, 53.37 mmol) were placed in a flask with Degassed 2-methyltetrahydrofuran (150 mL). Nitrogen was bubbled through the reaction mixture for 10 minutes, and then the reaction mixture was refluxed for 3 hours. The reaction mixture was cooled, diluted with water (400 mL), and extracted with EtOAc (2 x 300 mL). The combined organic phases were washed with saturated brine (200 mL), passed through a phase separation filter paper, and the solvent was removed under vacuum.The crude product was purified by flash chromatography on silica, gradient elution of EtOAc from 0 to 50% in heptane. The pure fractions were evaporated to dryness to yield the title compound (11.68 g, 68%) as a pale yellow foam. Ή NMR (400 MHz, DMSO-d6, 27 °C) -0.08 (9H, s), 0.82 - 0.86 (2H, m), 1.42 (9H, s), 2.99 (3H, s), 3.15 - 3.30 (2H, m), 3.52 (2H, dtd), 4.71 (1H, d), 4.88 (1H, dd), 4.94 - 5.10 (2H, m), 5.26 (1H, d), 5.55 (1H, d), 5.64 (1H, d), 6.69 (1H, s), 7.46 - 7.56 (1H, m), 7.57 - 7.66 (2H, m), 7.99 (1H, d), 9.18 (1H, s); m / z MH+643. BS Intermediate: (5)-2-((5-(( tert-butoxycarbonyl)amino)-6-fluoro-1-((2(trimethylsilyl)ethoxy)methyl)-1 H-pyrrolo[3,2-b ]pyridin-2-yl)methyl)-5-fluoro-3-oxo1- (2-oxoethyl) isoindoline-1-carboxylate methyl Petition 870250081337, dated 10 / 09 / 2025, pp. 46 / 64 38 / 47

[00104] To a solution of (5)-1-allyl-2-((5-(( tert-butoxycarbonyl)amino)-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)-1-pyrrolo[3,2-b ]pyridin-2-yl)methyl)-5-fluoro-3-oxoisoindoline-1-carboxylate methyl (11.50 g, 17.89 mmol) in 1,4-dioxane (240 mL) and water (60 mL), osmium(VIII) oxide (4% in water) (1.14 mL, 0.18 mmol), sodium periodate (9.57 g, 44.73 mmol) and 2,6-dimethylpyridine (4.17 mL, 35.78 mmol) were added. The reaction mixture was stirred at room temperature for 18 hours. The reaction mixture was partitioned between DCM (200 mL) and water (100 mL). The aqueous phase was extracted again with DCM (100 mL) and the organic phases were combined, passed through a phase separation filter paper, and the solvent was removed under vacuum. The crude product was purified by flash chromatography on silica, gradient elution of EtOAc from 0 to 50% in heptane. The pure fractions were evaporated to dryness to yield the title compound (8.70 g, 75%) as a beige foam.RMN de H (400 MHz, DMSO-d6, 27 °C) -0.07 (9H, s), 0.82 (2H, ddd), 1.42 (9H, s), 3.25 (3H, s), 3.46 - 3.54 (2H, m), 3.67 (2H, s), 4.92 (1H, d), 5.06 (1H, d), 5.52 (1H, d), 5.61 (1H, d), 6.57 (1H, s), 7.48 - 7.57 (1H, m), 7.64 (1H, dd), 7.68 (1H, dd), 8.00 (1H, d), 9.16 (1H, s), 9.25 (1H, s); m / z MH+645. (^f-(2-((1'-(but-2-in-1-il)-5-fluoro-2',3-dioxospiro[isoindolina-1,3'-pirrolidin]2-il)metil)-6-fluoro-1-((2-(trimetilsilil)etoxi)metil)-1 H-pirrolo[3,2-b ]piridin5-il)carbamato de terc-butila Petition: 870250081337, on September 10, 2025, page. 47 / 64 39 / 47

[00105] (5)-2-((5-(( tert-butoxycarbonyl)amino) -6-fluoro-1-((2(trimethylsilyl)ethoxy)methyl)-1 H-pyrrolo[3,2-b ]pyridin-2-yl)methyl)-5-fluoro-3-oxo1-(2-oxoethyl)isoindoline-1-carboxylate methyl (9.50 g, 14.73 mmol) and but-2-yn-1-amine hydrochloride (2.33 g, 22.10 mmol) were placed in a flask with 1,2-dichloroethane (100 mL). Triethylamine (3.08 mL, 22.10 mmol) was added and the reaction mixture was stirred at room temperature for 30 minutes. Sodium triacetoxyborohydride (6.25 g, 29.47 mmol) was added and the reaction mixture was stirred at room temperature overnight. The reaction mixture was diluted with DCM (250 mL) and washed sequentially with saturated NaHCO3 (100 mL), water (100 mL), and brine (100 mL). The organic phase was passed through a phase separation filter paper and the solvent was removed under vacuum to yield the title compound.The crude compound was used without further purification in the following reaction, assuming a 100% yield. m / z MH+666. (5)-2-((5-amino-6-fluoro-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl)-1'-(but-2-yn-1-yl)-5-fluorospiro[isoindoline-1,3'-pyrrolidine]-2',3-dione (Reference Form 1) Petition 870250081337, dated 10 / 09 / 2025, pp. 48 / 64 40 / 47 F F

[00106] (5)-( 2- ((l'-(but-2-yn-l-yl)-5-fluoro-2',3-dioxospiro [Isoindoline-1,3'-pyrrolidin]-2-yl)methyl)-6-fluoro-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-pyrrolo[3,2-b]pyridin-5-yl)tert-butyl carbamate (9.81 g, 14.73 mmol) was placed in a flask with 2,2,2-trifluoroacetic acid (22.55 mL, 294.7 mmol) and the solution was stirred for 2 hours at room temperature. The 2,2,2-trifluoroacetic acid was removed under vacuum and the residue was dissolved in MeCN (20 mL). Ammonium hydroxide (28 to 30% in water) (22.95 mL, 589.4 mmol) was added and the reaction mixture was stirred at 40 °C for 2 hours. The crude product was purified by reversed-phase chromatography (Interchim C18-HP Flash column, 415 g), using mixtures of water with decreasing polarities (containing, by volume, 1% NH4OH (28 to 30% in H2O)) and MeCN as eluents (gradient from 30 to 60%).The fractions containing the desired compound were combined, the MeCN was removed under vacuum, and the resulting solid was removed by filtration and dried to yield the title compound (3.74 g, 58%) as a creamy crystalline solid. ¹H NMR (400 MHz, DMSO-d6, 27 °C) 1.88 (³H, t), 2.36 - 2.44 (²H, m), 3.54 (¹H, ddd), 3.76 (¹H, dt), 4.08 (²H, qq), 4.24 (¹H, d), 5.03 (¹H, d), 5.49 (²H, s), 6.11 (¹H, d), 7.36 (¹H, dd), 7.49 - 7.64 (³H, m), 10.69 (¹H, d); m / z MH+436. Example 1: Preparation of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3l-pyrrolidine]1,2'-dione:hemiadipic acid co:crystal (“Form A of compound (I)). Method A: Single-solvent co-crystallization

[00107] Approximately 27.6 mg of adipic acid were dissolved Petition 870250081337, dated 10 / 09 / 2025, page 49 / 64 41 / 47 in 500 l / L of methanol and heated separately, approximately 150 mg of Reference Form 1 were dissolved in 2 mL of methanol with heating, subsequently these two solutions were combined and left on stirring with a magnetic stir bar at room temperature for 8 days with a slightly loose lid on the flask to allow slow evaporation. The resulting material was filtered, the solid recovered and dried under an air stream overnight, resulting in Form A of Compound (I) with a yield of approximately 53%.Method B: Antisolvent / Co-crystallization (unseeded)

[00108] Reference Form 1 (501.51 mg, 1.0942 mmol, 95 wt%) was loaded into an 8 mL flask, adipic acid (166.13 mg, 1.1368 mmol, 100 wt%) and dimethyl sulfoxide (3.54 g, 45.3 mmol, 100 wt%) were loaded and the contents stirred using a double impeller with 3 inclined blades at 600 rpm, heated to 25 °C and held at this temperature for 5 minutes. The contents of the flask were then heated at a rate of 5 °C / minute to 80 °C and the temperature was held for 20 minutes. Water (1.4 mL, 78 mmol, 100% by mass) was loaded into the flask at 80 °C for 2 hours at a rate of 0.012 mL / minute and the temperature maintained for a further 30 minutes. The contents of the flask were then cooled to 20 °C over 8 hours at a rate of 0.125 °C / minute and the temperature maintained for 80 hours.The contents of the flask were further cooled to 5 °C over 15 minutes and the temperature maintained for 3 hours, then heated to 20 °C and water (0.75 mL, 42 mmol, 100% by mass) was added to the flask during which crystallization occurred. The contents of the flask were then discharged onto a filter (30 mm diameter filter paper) under ambient conditions and deliquesced under vacuum. Premixed dimethyl sulfoxide (0.525 mL, 7.4 mmol, 100% by mass) and water (0.225 mL, 12.5 mmol, 100% by mass) were added to the container under ambient conditions for washing. The contents of the flask were shaken a. Petition 870250081337, dated 10 / 09 / 2025, pages 50 / 64 42 / 47 °C and then discharged onto the filter under ambient conditions and deliquesced under vacuum. This step was repeated for a second wash, after which 2-propanol (1.00 mL, 13.1 mmol, 100% by mass) was loaded onto the filter and the contents were deliquesced under vacuum. This step was repeated for the final wash, after which the filter contents were discharged onto a drying dish and vacuum dried in an oven at 45 to 50 °C for 24 hours, resulting in Compound Form A (I) with a yield of approximately 92%. Method C: Cooling / Antisolvent Co-crystallization (Seeding)

[00109] Reference Form 1 (8.01 g, 18.2 mmol, 99% by mass) was loaded into a 100 mL container, adipic acid (2.57 g, 17.6 mmol, 100% by mass) and dimethyl sulfoxide (54.88 g, 702.4 mmol, 100% by mass) were loaded and the contents were stirred using a 4-bladed inclined propeller impeller at 400 rpm, heated to 25 °C and held at this temperature for 30 minutes. The contents of the container were then heated at a rate of 5 °C / minute to 80 °C and the temperature held for 20 minutes. Water (21.6 mL, 1200 mmol, 100% by mass) was charged into the container at 80 °C for 2 hours at a rate of 0.1125 mL / minute and the temperature maintained for a further 5 minutes. The contents of the container were then cooled to 65 °C for 30 minutes at a rate of 0.5 °C / minute and the temperature maintained for 30 minutes.The seed (prepared according to Method B; 8.7 mg, 0.017 mmol, 100% by mass) was then loaded into the container at 65 °C and the temperature maintained for 3 hours. The contents of the container were then cooled to 20 °C over 6 hours at a rate of 0.125 °C / minute and the temperature was maintained for a further 3 hours. The antisolvent, water (12 mL, 666.119 mmol, 100% by mass), was loaded into the container at 20 °C for 6 hours and the temperature was maintained for a further 6 hours. The contents of the container were then discharged onto a filter (63 mm diameter) under ambient conditions and deliquesced under vacuum, resulting in a height of... Petition 870250081337, dated 10 / 09 / 2025, pp. 51 / 64 43 / 47 8 mm cake. Premixed dimethyl sulfoxide (7.2 mL, 100 mmol, 100% by mass) and water (4.8 mL, 270 mmol, 100% by mass) were loaded into the container under ambient conditions for washing. The contents of the container were stirred at 20 °C and then discharged onto the filter under ambient conditions and deliquesced under vacuum. This step was repeated for a second wash, after which 2-propanol (16 mL, 209 mmol, 100% by mass) was loaded onto the filter and the contents were deliquesced under vacuum. This step was repeated for the final wash, after which the contents of the filter were discharged onto a drying dish and dried under vacuum in an oven at 45 to 50 °C for 17 hours, resulting in Form A of Compound (I) with a yield of approximately 85%. Example 2: XRPD Analysis of the Polymorph of Form A of Compound (I)

[00110] The powder X-ray diffractogram was recorded with a two-theta scan axis and in one-dimensional scanning with a Rigaku SmartLab (X-ray wavelength 1.5418 Â of nickel-filtered Cu α radiation, 40 kV, 50 mA) equipped with a D / tex Ultra 250 detector and optical CBO-E. The sample was rotated at 30 revolutions per minute during the measurement. The sample was scanned from 3 to 40° 2-theta using a step width of 0.01° and a scan rate of 0.1° / min. The powder sample was packed in a long glass capillary with an outer diameter of 0.9 mm.

[00111] The 2-theta values ​​(in degrees) and relative peak intensities derived from the XRPD trace that characterize Form A are shown in Table 3 below: Table 3. Complete list of peaks in the X-ray powder diffraction pattern of Form A, in the range of 3 to 30° 2θ.________________________________________ 2θ,° Relative intensity 2θ,° Relative intensity 8.9 very strong 20.5 medium 11.8 medium 20.6 medium 12.2 medium 21.2 strong 14.5 strong 22.2 weak Petition 870250081337, dated 10 / 09 / 2025, pages 52 / 64 44 / 47 15.4 weak 22.9 very strong 15.5 weak 23.4 medium 15.8 medium 23.7 strong 16.1 weak 24.7 weak 16.9 strong 25.1 medium 17.4 strong 25.8 strong 17.6 medium 26.4 weak 17.8 weak 26.6 medium 17.9 weak 27.0 strong 17.9 weak 27.3 medium 18.2 medium 27.9 weak 18.6 weak 28.1 strong 19.1 very strong 28.6 medium 19.4 medium 28.8 weak 19.7 very strong 29.2 strong

[00112] Relative intensity refers to the size of the integrated peak normalized to that of the largest peak with the categories defined as in Table 1. Results

[00113] The powder X-ray diffraction pattern shown in Figure 1 demonstrates that Form A of Compound (I) is highly crystalline. Example 3: Properties of reference form 1 and form A of compound (I) Differential scanning calorimetry (DSC)

[00114] Thermal events were analyzed by standard-mode differential scanning calorimetry on a TA Discovery DSC instrument. Approximately 1.5 to 2.0 mg of material contained in a standard closed aluminum pan were measured over the temperature range of 25 °C to 300 °C at a constant heating rate of 10 °C / minute. Nitrogen was used as a purge gas at a flow rate of 50 mL / minute. Thermogravimetric analysis (TGA)

[00115] Weight loss was analyzed by standard thermogravimetric analysis on a TA Discovery TGA instrument. Approximately 3 to 5 mg Petition 870250081337, dated 10 / 09 / 2025, pages 53 / 64 45 / 47 of the material placed in a 100 μE platinum pan was heated to 300 °C from the instrument's ambient temperature at a constant heating rate of 10 °C / minute. Nitrogen was used as a purge gas at a flow rate of 25 mE / minute. Dynamic vapor solvation (DVS)

[00116] Approximately 5 to 10 mg of material were weighed into an aluminum sample pan and subjected to the following relative humidity profile using a Surface Measurement Systems DVS Resolution instrument: 40-90-0-90-0% relative humidity with 10% relative humidity steps and a dm / dt limit of 0.002% and a maximum step time limit of six hours. The temperature was maintained at approximately 25 °C throughout the process. Results

[00117] The results of the DSC and TGA experiments for Reference Form 1 and Compound Form (I) are shown in Figures 2 and 3, respectively. The results of the DVS experiments for Reference Form 1 and Compound Form (I) are shown in Figures 4 and 5, respectively.

[00118] Thermal analysis of Reference Example 1 by DSC shows a broad endotherm indicative of desolvation followed by a single melting endotherm (melting peak: endothermic, onset 164.08 °C, peak 168.52 °C, enthalpy 44.746 J / g) (Figure 2). A single melting endotherm for Form A of Compound (I) was observed (melting peak: endothermic, onset 216.63 °C, peak 217.70 °C, enthalpy 122.48 J / g) (Figure 3).

[00119] The TGA of Reference Form 1 shows a weight loss of 1.617% at 100 °C due to desolvation, indicating an initial hydrated form (Figure 2). TGA of Compound Form (I) showed no significant weight loss before the melting point, indicating an anhydrous form (Figure 3). Petition 870250081337, dated 10 / 09 / 2025, pp. 54 / 64 46 / 47

[00120] DVS analysis shows that Reference Form 1 undergoes reversible hydration from hemihydrate to monohydrate at high relative humidity and reversible dehydration from hemihydrate to anhydrate at low relative humidity (Figure 4). DVS analysis also reveals that Reference Form 1 has a moisture absorption of 3.37% at 80% relative humidity (Figure 4).

[00121] In contrast, Compound Form A (I) has very low hygroscopicity, with moisture absorption from 0.50% to 80% relative humidity (Figure 5).

[00122] Therefore, the results show that Form A of Compound (I) exhibits high thermal stability, is not solvated, and has low hygroscopicity. Example 4: Solubility of reference form 1 and form A of compound ω

[00123] The results of the preliminary solubility test of the Reference Form (I) and Form A of Compound (I) over 24 hours at 37 °C are shown in Table 4. Table 4, Solubility in biorelevant media of Form A of Compound (I) and of Reference Form 1.______________________________________________ Solubility (μM) Medium Compound Form A (I) Reference Form 1 SGF 21152* 42704* FaSSIFv2 1161 747 FaSSIF blank 369 250 FeSSIF 1376 830 FeSSIF blank 649 659 * Unsaturated samples; SGF (simulated gastric fluid) = simulated gastric fluid; FaSSIF (fasted state simulated intestinal fluid) = fasted state simulated intestinal fluid; FeSSIF (fed state simulated intestinal fluid) = fed state simulated intestinal fluid Results

[00124] The results show that Form A of Compound (I) is more soluble than Reference Form 1 in a variety of media. Petition 870250081337, dated 10 / 09 / 2025, pages 55 / 64 47 / 47 biorelevant (Table 4). The solubility test in SGF was inconclusive, as both samples were unsaturated. Example 5: Physical stability of form A of compound (I)

[00125] The physical stability of Compound (I) Form A was evaluated by an aqueous fluid paste method. Approximately 15 mg of Compound (I) Form A were weighed into a flask and 250 µL of water were added. This was stirred using a magnetic stir bar at room temperature for 10 days, then filtered using a 0.45 µm centrifuge filter (13,000 rpm for 5 minutes) and analyzed by XRPD, which showed no shape change in the Compound (I) Form A material, indicating that Compound (I) Form A appears to be physically stable. Conclusions

[00126] The results of the above experiments demonstrate that Compound (I) Form A is a distinct crystalline form that is more thermally stable than Reference Form 1. Compound (I) Form A is anhydrous, unlike Reference Form 1, which exhibits variable (de)hydration due to its sensitivity to temperature and / or humidity. Compound (I) Form A is less hygroscopic than Reference Form 1, and preliminary solubility data suggest that Compound (I) Form A is more soluble than Reference Form 1 in a variety of biorelevant media. Compound (I) Form A also appears to be physically stable.

Claims

1. Crystalline form, characterized by being a cocrystal of (3S)-2-[(5-amino-6-fluoro-1H-pyrrolo[3,2-b]pyridin-2-yl)methyl]-1'-but-2-ynyl-6-fluoro-spiro[isoindoline-3,3'-pyrrolidine]-1,2'-dione: F Compound (I), and adipic acid in a 2:1 ratio (Form A of Compound (I)).

2. Crystalline form according to claim 1, the crystalline form being characterized in that it has a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 19.1, 19.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation.

3. Crystalline form according to claim 1 or 2, the crystalline form being characterized in that it has a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, 14.5, 16.9, 17.4, 19.1, 19.7, 21.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation.

4. Crystalline form according to any one of claims 1 to 3, the crystalline form being characterized in that it has a powder X-ray diffraction substantially as shown in Figure 1 when measured using CuKa radiation.

5. Crystalline form according to any one of claims 1 to 4, the crystalline form being characterized in that it has a DSC thermogram substantially as shown in Figure 3.

6. Crystalline form according to claim 1, the form Petition 870250081337, dated 10 / 09 / 2025, p.57 / 64 2 / 3 crystalline being characterized by being a cocrystal of (3S)-2-[(5amino-6-fluoro-lH-pyrrolo[3,2-b]pyridin-2-yl)methyl]-l'-but-2-ynyl-6-fluorospiro[isoindoline-3,3'-pyrrolidine]-l,2'-dione: F Compound (I), and adipic acid in a 2:l ratio (Form A of Compound (I)), having at least one of the following: a) a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, l9.1, l9.7 and 22.9 degrees 2-theta when the measurement is made using CuKa radiation; b) a powder X-ray diffraction pattern containing specific peaks at (±0.2) 8.9, l4.5, l6.9, l7.4, l9.1, l9.7, 2l.2, 22.9, 23.7 and 25.8 degrees 2-theta when the measurement is made using CuKa radiation; c) a powder X-ray diffraction pattern substantially as shown in Figure 1; d) a DSC thermogram with an initial melt at 2l6.6 °C plus or minus 5 °C and a peak at 2l7.7 °C plus or minus 5 °C; e) a DSC thermogram and, optionally, a TGA thermogram substantially as shown in Figure 3.

7. Pharmaceutical composition, characterized in that it comprises the crystalline form as defined in any one of claims 1 to 6 and at least one pharmaceutically acceptable excipient.

8. Crystalline form according to any of claims 1a 6, or pharmaceutical composition according to claim 7, characterized in that it is intended for use as a medicament, for example, in the prophylaxis or treatment of a PRMT5-mediated disorder.

9. Use of the crystalline form according to any one of claims 1 to 6, or of the pharmaceutical composition according to claim 7, characterized in that it is used in the manufacture of a medicament, for example, for the prophylaxis or treatment of a PRMT5-mediated disorder.

10. Method for preventing or treating, for example, preventing or treating a PRMT5-mediated disorder, characterized in that it comprises administering the crystalline form as defined in any one of claims 1 to 6, or the pharmaceutical composition as defined in claim 7.

11. Crystalline form for use, pharmaceutical composition for use, use or method according to any of claims 8 to 10, characterized in that the disorder is cancer.

12. Crystalline form for use, pharmaceutical composition for use, use or method according to claim 11, characterized in that the cancer is an MTAP deletion cancer.

13. Crystalline form for use, pharmaceutical composition for use, use or method according to claim 11 or 12, characterized in that the cancer is selected from among gastric, pancreatic, colorectal, uterine, bile duct, stomach, bladder, cervical, testicular germ cell, lung (e.g., non-small cell lung cancer), multiple myeloma, lymphoma (e.g., diffuse large B-cell lymphoma or Hodgkin's lymphoma), rhabdomyosarcoma and cutaneous squamous cell carcinoma.

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