HH3806

HH3806 is a highly selective small molecule inhibitor of the second bromodomain (BD2) of the Bromodomain and Extra-Terminal (BET) family proteins, which include BRD2, BRD3, and BRD4. Developed by Haihe Biopharma (also known as Chengdu Haihe Medical Technology), HH3806 is designed to treat advanced solid tumors and hematologic malignancies. Unlike pan-BET inhibitors that target both the BD1 and BD2 domains, HH3806's selectivity for the BD2 domain is intended to maintain potent anti-tumor activity while potentially reducing dose-limiting toxicities, such as thrombocytopenia and gastrointestinal issues, often associated with non-selective BET inhibition. Preclinical studies demonstrated favorable pharmacokinetic properties, an acceptable safety profile, and potent anti-tumor efficacy. As of early 2023, HH3806 has entered Phase I clinical development, with the first patient dosed in a multi-center trial in Australia for patients with advanced solid tumors.