Phase 1 Study of OP-3136 in Advanced or Metastatic Solid Tumors

Part 1A (Dose Escalation for OP-3136 Monotherapy): This part of the study will evaluate the safety, tolerability, and PK in a range of doses of OP-3136, a lysine acetyltransferases 6A and 6B (KAT6A/B) inhibitor, administered orally once daily to participants with ER+ HER2- advanced or metastatic breast cancer (mBC), advanced or metastatic castration resistant prostate cancer (mCRPC), or advanced or metastatic non-small cell lung cancer (mNSCLC), and determine the maximum tolerated dose (MTD) and the recommended dose/regimen for expansion (RDE). Part 1B (Dose Escalation for OP-3136 in Combination with Fulvestrant): This part of the study will evaluate the safety and PK of OP-3136 administered in combination with fulvestrant in participants with ER+ HER2- mBC, and determine MTD and RDE for this combination. Part 1C (Dose Escalation for OP-3136 in Combination with Palazestrant): This part of the study will evaluate the safety and PK of OP-3136 administered in combination with palazestrant in participants with ER+ HER2- mBC, and determine MTD and RDE for this combination. Part 2A (Dose Expansion for OP-3136 Monotherapy): This part will evaluate two expansion cohorts at the monotherapy RDE from part 1 in participants with ER+ HER2- mBC and participants with mCRPC. Part 2B (Dose Expansion for OP-3136 in Combination with Fulvestrant OR Palazestrant): This part will evaluate the RDEs for OP-3136 in combination with fulvestrant from Part 1B OR the RDEs of OP-3136 in combination with palazestrant in an expansion cohort in participants with ER+ HER2- mBC.