Anbogen, a Taiwan-based clinical-stage biotech startup, has announced a drug supply collaboration to evaluate the combination of Anbogen's HDAC inhibitor, ABT-301, with China-based BeiGene's anti-PD-1 antibody tislelizumab, in patients with mismatch repair–proficient (pMMR) or microsatellite stable (MSS) metastatic colorectal cancer (mCRC) in a global Phase II trial. Under the terms of the agreement, BeiGene will supply tislelizumab to Anbogen for the study.

In 2020, over 1.9 million new cases of colorectal cancer were diagnosed globally. Immune checkpoint inhibitors (ICIs) have emerged as a primary treatment for metastatic colorectal cancer (mCRC) with mismatch repair deficiency (dMMR) or high microsatellite instability (MSI-H). However, this innovative therapy benefits only a small fraction of patients, as less than 5% of mCRC cases exhibit dMMR/MSI-H. Consequently, there remains a significant unmet need for the 95% of patients with pMMR/MSS tumours, who do not respond to ICIs.

ABT-301, a novel HDAC inhibitor, has shown promising safety and pharmacokinetic profiles in a prior Phase 1 study as a single agent. Preclinical studies indicate that ABT-301 enhances the effectiveness of anti-PD-1/anti-PD-L1 therapies by increasing CD8+ cytotoxic T cells and decreasing monocytic myeloid-derived suppressor cells within both the tumuor and circulation, and inhibiting angiogenesis. These immune response enhancements may broaden the efficacy of ICIs in colorectal cancer patients. The upcoming Phase II study will investigate the effectiveness of treatment regimens combining ABT-301 and tislelizumab, with and without Bevacizumab, in pMMR/MSS mCRC patients with significant unmet needs.

The clinical trial will be conducted in multiple centers and will evaluate the safety, tolerability, and preliminary efficacy of the combination therapy in patients with advanced MSS CRC. The study is expected to begin enrollment in the first quarter of 2025.