New Drug Approvals

Imofinostat

CAS 1338320-94-7

MF C17H16N2O4S MW 344.4 g/mol

• 3-(1-(Benzenesulfonyl)-2,3-dihydro-1H-indol-5-yl)-N-hydroxyacrylamide
• (E)-3-[1-(benzenesulfonyl)-2,3-dihydroindol-5-yl]-N-hydroxyprop-2-enamide

(2E)-3-[1-(benzenesulfonyl)-2,3-dihydro-1H-indol-5-yl]-N-hydroxyprop2-enamide
histone deacetylase inhibitor, antineoplastic, ABT-301, MPT0E028, ABT 301, MPT0E 028, T65L58FI65

Imofinostat (also known as ABT-301 or MPT0E028) is an orally bioavailable, small-molecule histone deacetylase (HDAC) inhibitor primarily being developed as an innovative precision oncology treatment. Developed by companies like AnBogen Therapeutics and Formosa Pharmaceuticals, it is designed to reactivate tumor suppressor genes that cancer cells have silenced, thereby triggering cancer cell death (apoptosis) and stopping tumor growth.

Mechanism of Action

Imofinostat works through a distinct multi-modality approach to fight cancer cells:

• HDAC Inhibition: It acts as a potent inhibitor of human pan-histone deacetylase enzymes, showing preferential selectivity for Class I HDACs (especially HDAC3). This blocks the deacetylation of histone proteins, causing chromatin to remodel and forcing cancer cells to express tumor-suppressor genes.
• Akt Pathway Targeting: Independent of its epigenetic effects, it can directly target and reduce the activation (phosphorylation) of the Akt protein kinase, a major pathway that cancer cells use to survive and multiply.
• Microenvironment Modulation: Preclinical data shows it alters the tumor microenvironment by converting “cold tumors” (invisible to the immune system) into “hot tumors” by promoting the infiltration of CD8+ cytotoxic T cells.

Current Clinical Status & Indications

Imofinostat is actively moving through clinical trial pipelines, focusing heavily on combination therapies to overcome treatment resistance:

• Colorectal Cancer (CRC): It is currently being evaluated in a global Phase 1/2 clinical trial (NCT07244705). It is combined with the immune checkpoint inhibitor tislelizumab (Tevimbra®) and the anti-angiogenic drug bevacizumab to treat advanced, metastatic colorectal cancer.
• Pancreatic Cancer: Recent data presented at the 2026 American Association for Cancer Research (AACR) Annual Meeting demonstrates that imofinostat disrupts the HDAC3-NRF2 pathway. This action breaks down chemotherapy resistance in highly aggressive KRAS-mutant pancreatic ductal adenocarcinoma, making tumors much more sensitive to treatments like gemcitabine.
• Other Solid Tumors: Phase 1 monotherapy trials have confirmed that the drug possesses a highly competitive safety profile across a broad variety of advanced solid tumors.

Imofinostat is an orally bioavailable N-hydroxyacrylamide-derived inhibitor of both human pan-histone deacetylase (HDAC) enzymes and the serine/threonine protein kinase Akt (protein kinase B), with potential antineoplastic activity. Upon administration, imofinostat selectively binds to and inhibits HDACs, which inhibits deacetylation of histone proteins and leads to the accumulation of highly acetylated histones. This may result in both an induction of chromatin remodeling, and the selective transcription of tumor suppressor genes. This prevents cell division and induces both cell cycle arrest and apoptosis, which may inhibit the proliferation of susceptible tumor cells. In addition, imofinostat inhibits the phosphorylation and activation of Akt, which prevents the activation of downstream signaling pathways, independent of its HDAC inhibitory activity. HDACs, upregulated in many tumor cell types, are a family of enzymes that deacetylate histone proteins. Akt, overexpressed in many tumor cell types, plays a key role in tumor cell proliferation and survival.

Dose-Seeking Study of MPT0E028 in Subjects With Advanced Solid Malignancies Without Standard Treatment

CTID: NCT02350868

Phase: Phase 1

Status: Completed

Date: 2019-04-11

PAT

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2011126821&_cid=P11-MQ4LAI-84972-1

COMD 12

Compound 12 was synthesized via the route as shown in Scheme 3 above (reagents and conditions: (a) NaBH₃CN, AcOH; (b) Benzenesulfonyl chloride, 4-methoxybenzenesulfonyl chloride, 3,4-dimethoxybenzenesulfonyl chloride, 4-fluorobenzenesulfonyl chloride, or 4-nitrobenzenesulfonyl chloride, pyridine; (c) L1AIH₄, THF; (d) PDC, MS, CH₂C1₂; f) Ph₃P = CH-COOCH₃, CH₂C1₂; (g) 1M LiOH(aq), dioxane; (h) (i) NH₂OTHP, PyBOP, NEt₃, DMF; (ii) TFA, MeOH; (i) Fe, NH₄C1, Isopropanol, H₂0).

2,3-Dihydro-lH-indole-5-carboxylic acid methyl ester (10): sodium cyanoborohydride (0.16 g, 2.57 mmol) was added to a solution of methyl indole-5-carboxylate (9) (0.30 g, 1.71 mmol) in AcOH (2 mL) at 0 °C. The reaction mixture was warmed to room temperature and stirred for 2 h before it was quenched with water at 0 °C. Concentrated NaOH was added to reach pH=10. The aqueous layer was extracted with CH₂CI₂ (15 mL x 3). The combined organic layer was dried over anhydrous MgS0₄ and concentrated under reduced pressure to give a yellow residue, which was purified by silica gel chromatography (EtOAc: n-hexane = 1 : 2) to afford 10 (0.28 g). 1H NMR (500MHz, CDC1₃): δ 3.06 (t, J= 8.5 Hz, 2H), 3.65 (t, J= 8.5 Hz, 2H), 3.84 (s, 3H), 6.53-6.55 (m, 1H), 7.75-7.76 (m, 2H).

l-Benzenesulfonyl-2,3-dihydro-lH-indole-5-carboxylic acid methyl ester (11): To a solution of 10 (0.28 g, 1.58 mmol) in pyridine (2 mL), benzenesulfonyl chloride (0.40 ml, 3.16 mmol) was added. The reaction mixture was refluxed overnight. The mixture was then purified by silica gel chromatography (EtOAc: n-hexane = 1 : 3) to afford 11 (0.40 g). 1H NMR (500MHz, CDCI₃): δ 2.99 (t, J= 8.6 Hz, 2H), 3.87 (s, 3H), 3.97 (t, J= 8.6 Hz, 2H), 7.45-7.48 (m, 2H), 7.56-7.59 (m, 1H), 7.66 (d, J= 8.5 Hz, 1H), 7.75 (s, 1H), 7.82 (d, J= 7.7 Hz, 2H), 7.90 (d, J= 7.9 Hz, 1H).

(l-Benzenesulfonyl-2,3-dihydro-lH-indol-5-yl)-methanol (12): LAH (0.10 g, 2.52 mmol) was added to a solution of 11 (0.40 g, 1.26 mmol) in THF (10 mL) at 0 °C. The reaction mixture was warmed to room temperature and stirred for 2 h before it was quenched with water and then extracted with CH₂CI₂ (15 mL x 3). The combined organic layer was dried over anhydrous MgS0₄ and concentrated under reduced pressure. The reaction mixture was purified by silica gel chromatography (EtOAc: n-hexane = 1 : 1) to afford 12 (0.24 g). 1H NMR (500MHz, CDC1₃): δ 2.83 (t, J= 8.4 Hz, 2H), 3.92 (t, J= 8.5 Hz, 2H), 4.49 (s, 2H), 7.09 (s, 1H), 7.16 (d, J= 8.2 Hz, 1H), 7.46-7.49 (m, 2H), 7.53 (d, J= 8.2 Hz, 1H), 7.60 (t, J= 7.5 Hz, 1H), 7.76 (d, J= 7.7 Hz, 2H).

l-Benzenesulfonyl-2,3-dihydro-lH-indole-5-carbaldehyde (13): molecular sieves (0.63g) were added to a solution of 12 (0.24 g, 0.83 mmol) in CH₂C1₂ (10 mL), PDC (0.63 g, 1.66 mmol). The mixture was stirred at room temperature overnight before it was filtered through celite. The organic layer was concentrated under reduced pressure then purified by silica gel chromatography (EtOAc: n-hexane = 1 : 2) to afford 13 (0.19 g). 1H NMR (500MHz, CDC1₃): δ 3.05 (t, J= 8.6 Hz, 2H), 4.01 (t, J= 8.7 Hz, 2H), 7.46-7,49 (m, 2H), 7.58-7.62 (m, 2H), 7.71 (d, J= 8.3 Hz, 1H), 7.75 (d, J= 8.3 Hz, 1H), 7.84 (d, J= 7.8 Hz, 2H), 9.85 (s, 1H).

3-(l-Benzenesulfonyl-2,3-dihydro-lH-indol-5-yl)-acrylic acid methyl ester (14): Methyl (triphenylphosphoranylidene) acetate (0.27 g, 0.79 mmol) was added to a solution of 13 (0.19g,

0.66 mmol) in CH₂CI₂ (10 mL). The mixture was stirred at room temperature for 3h before it was

quenched with water and then extracted with CH₂CI₂ (15 mL x 3). The combined organic layer was dried over anhydrous MgS0₄ and concentrated under reduced pressure to give a yellow residue, which was then purified by silica gel chromatography (EtOAc: n-hexane = 1 : 3) to afford 14

(0.20 g).

3-(l-Benzenesulfonyl-2,3-dihydro-lH-indol-5-yl)-acrylic acid (15): 1M LiOH aqueous solution (1.16 ml, 1.16 mmol) was added to a solution of 14 (0.20g, 0.58 mmol) in dioxane

(15 mL). The reaction mixture was stirred at 40 °C overnight before it was concentrated under reduced pressure. The residue was dissolved in water and concentrated HCl was added up to acidic pH to give the precipitation, which was dried by vacuum to afford 15 (0.16 g). 1H NMR (500MHz, CD₃OD): δ 2.92 (t, J= 8.5 Hz, 2H), 3.96 (t, J= 8.5 Hz, 2H), 6.33 (d, J= 15.9 Hz, 1H), 7.38 (s, 1H), 7.41 (d, J= 8.5 Hz, 1H), 7.50-7.53 (m, 2H), 7.55 (d, J= 16.1 Hz, 1H), 7.58-7.64 (m, 2H), 7.82 (d, J = 7.6 Hz, 2H).

3-(l-Benzenesulfonyl-2,3-dihydro-lH-indol-5-yl)-N-hydroxy-acrylamide

(Compound 12): NH₂OTHP (0.05 g, 0.44 mmol) was added to a solution of 15 (0.12 g, 0.37 mmol), PyBOP (0.20 g, 0.39 mmol), triethylamine (0.12 ml, 0.88 mmol) in DMF (1.5 mL). The reaction mixture was stirred at room temperature for 1 h before it was quenched with water, followed by extraction with EtOAc (15 mL x 3). The combined organic layer was dried over anhydrous MgS0₄ and concentrated under reduced pressure. The residue was purified by silica gel chromatography (CH₂C1₂: CH3OH = 30 : 1 : l%NH_3(aq)) to give a white solid, which was treated with TFA (1.13 ml, 15.21 mmol) in the presence of CH₃OH (25 mL) and stirred overnight at room temperature. The reaction mixture was concentrated under reduced pressure to give a white residue, which was recrystallized by CH₃OH to afford Compound 12 (0.12 g). 1H NMR (500MHz,

CD₃OD): δ 2.91 (t, J= 8.5 Hz, 2H), 3.96 (t, J= 8.4 Hz, 2H), 6.32 (d, J= 15.8 Hz, 1H), 7.32 (s, 1H), 7.37-7.39 (m, 1H), 7.46 (d, J= 15.7 Hz, 1H), 7.50-7.53 (m, 2H), 7.58-7.64 (m, 2H), 7.82 (d, J= 7.8 Hz, 2H). MS (EI) mlz: 170 (100%), 344 (M⁺, 3.21%). HRMS (EI) for Ci₇Hi₆N₂0₄S (M⁺): calcd, 344.0831; found, 344.0829.

PAT

 US20150368195

https://patentscope.wipo.int/search/en/detail.jsf?docId=US154007904&_cid=P11-MQ4M0P-01888-1

PAT

• Indolyl or indolinyl hydroxamate compoundsPublication Number: US-8846748-B2Priority Date: 2010-03-29Grant Date: 2014-09-30
• Indolyl or indolinyl hydroxamate compoundsPublication Number: US-9598364-B2Priority Date: 2010-03-29Grant Date: 2017-03-21
• Indolyl or indolinyl hydroxamate compoundsPublication Number: WO-2011126821-A2Priority Date: 2010-03-29
• Indolyl or indolinyl hydroxamate compoundsPublication Number: EP-2552887-A2Priority Date: 2010-03-29
• Indolyl or indolinyl hydroxamate compoundsPublication Number: US-2011245315-A1Priority Date: 2010-03-29
• Indolyl or indolinyl hydroxamate compoundsPublication Number: US-2014364477-A1Priority Date: 2010-03-29
• Indolyl or indolinyl hydroxamate compoundsPublication Number: EP-2552887-B1Priority Date: 2010-03-29Grant Date: 2018-10-24

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References

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