BAY 140

BAY 140 is a potent and selective small molecule inhibitor of the BRPF1 (Bromodomain and PHD finger-containing protein 1) bromodomain, originally identified and characterized by Bayer. It demonstrates high affinity for the BRPF1 bromodomain with an IC50 of approximately 30 nM in biochemical assays and shows significant selectivity over other bromodomain-containing proteins, including BRPF2 and BRD4. While BAY 140 has been evaluated for its anti-proliferative activity in various cancer models—including bladder, ovarian, small cell lung cancer, and acute myeloid leukemia—it typically exhibits only modest cellular potency (micromolar range). Consequently, it is primarily utilized as a chemical probe to investigate the biological roles of BRPF1 in epigenetic regulation, development, and cell differentiation.