UPDATE: Phase 1 Trial for OP-3136 in mCRPC Started Recruiting

The first-in-human phase 1 trial of OP-3136, a novel orally bioavailable KAT6A/B inhibitor for solid tumors, started recruiting, with the prostate cancer cohort focusing on men with metastatic castration-resistant prostate cancer (mCRPC). This represents a significant expansion of OP-3136 beyond its initial focus on estrogen receptor-positive breast cancer, following encouraging preclinical data presented at AACR 2025 that demonstrated potent anti-tumor activity in prostate cancer xenograft models.

OP-3136 works through selective inhibition of lysine acetyltransferases KAT6A and KAT6B, epigenetic regulators implicated in oncogenic transcriptional programs. The drug demonstrated highly selective activity against KAT6 family members in nonclinical studies and showed dose-dependent tumor growth inhibition in prostate xenograft models, with particular synergy observed when combined with docetaxel. The mechanism targets epigenetic dysregulation present in both hormone-sensitive and castration-resistant prostate cancer, representing a novel approach to an increasingly resistant disease.

Clinical trial.