Anbogen Therapeutics announced that the U.S. Food and Drug Administration has approved its Investigational New Drug 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. The FDA clearance represents a significant milestone for addressing the substantial unmet medical need in colorectal cancer immunotherapy.
Novel Triplet Combination Targets "Cold Tumors"
The open-label, multi-center international study plans to enroll 66 patients with proficient mismatch repair (pMMR) or non-microsatellite instability-high (non-MSI-H) metastatic colorectal cancer. Enrollment is planned in Taiwan and Australia, with tislelizumab, a PD-1 monoclonal antibody, provided by BeOne Medicines (formerly known as BeiGene).
ABT-301 is an oral HDAC1/2/3 inhibitor that has demonstrated unique immune-modulating capabilities in preclinical studies. The compound 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.
Addressing a Major Clinical Challenge
Approximately 95% of metastatic colorectal cancer 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.
Favorable Safety Profile
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. This safety profile further supports its suitability for use in combination immunotherapy.
Strategic Development Plans
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.
