On August 4, 2025 Anbogen Therapeutics reported that the U.S. Food and Drug Administration (FDA) has approved its Investigational New Drug (IND) application for ABT-301, enabling the initiation of a Phase 1/2 clinical trial in combination with tislelizumab and bevacizumab for patients with metastatic colorectal cancer (mCRC) (Press release, Anbogen Therapeutics, AUG 4, 2025, View Source [SID1234654738]).
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This open-label, multi-center international study plans to enroll 66 patients with proficient mismatch repair (pMMR) or non-microsatellite instability-high (non-MSI-H) mCRC to evaluate the safety and preliminary efficacy of the triplet therapy. Enrollment is planned in Taiwan and Australia. Tislelizumab, a PD-1 monoclonal antibody, used in this trial is provided by BeOne Medicines (formerly known as BeiGene). Further details on this collaboration were disclosed by Anbogen in a press release dated September 27, 2024.
ABT-301 is an oral HDAC1/2/3 inhibitor. Preclinical studies have shown that it promotes CD8+ cytotoxic T cell infiltration and activity, enhances antigen presentation, and inhibits M-MDSCs cells, effectively modulating the tumor microenvironment and converting "cold tumors" into "hot tumors" to improve the efficacy of immune checkpoint inhibitors. ABT-301 also exhibits pro-apoptotic, anti-angiogenic, and tumor metabolic regulation effects. As a single-molecule, multi-modality anti-cancer agent, ABT-301 aims to enhance tumor treatment when combined with the two antibody drugs.
Notably, in a previous Phase 1 monotherapy clinical trial involving 23 participants, ABT-301 did not exhibit neutropenia or cardiac toxicity, which are commonly observed in other HDAC inhibitors—further supporting its suitability for use in combination immunotherapy.
Approximately 95% of mCRC patients are pMMR or non-MSI-H types—commonly referred to as "cold tumors"—which respond poorly to current immunotherapies. Only around 5% of patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) "hot tumors" typically benefit from immune checkpoint inhibitors. According to GlobalData, an estimated 370,000 new pMMR/non-MSI-H patients in second-line or later settings are diagnosed annually across the U.S., China, Japan, and the top five European markets (UK, France, Germany, Spain, and Italy), representing a potential market size of USD $9 billion.
Anbogen stated that the FDA’s IND approval marks a key milestone in the development of ABT-301, demonstrating the safety profile of the triplet therapy and advancing it into clinical stages. The company emphasized that the study targets the majority of patients (over 90%) with poor responses to immunotherapy, aiming to provide a novel treatment option and address this unmet clinical need.
Looking ahead, Anbogen will continue to advance the clinical development of ABT-301 while pursuing global licensing and strategic partnerships to accelerate commercialization and market entry. The company is also launching its Series B fundraising to attract strategic partners committed to advancing innovative cancer therapies and global expansion.