This is a first-in-human, open-label, multicenter phase 1 study to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy of OP-3136, a lysine acetyltransferases 6A and 6B (KAT6A/B) inhibitor, as monotherapy and in combination with other anticancer agents in participants with advanced solid tumors.
This study consists of 2 parts: a dose escalation part (Part 1) and dose expansion part (Part 2).
Participants with advanced or metastatic ER+HER2- breast cancer, mCRPC, or NSCLC (Part 1) or advanced or metastatic ER+HER2- BC or mCRPC (Part 2).
Part 1A (Dose escalation for OP-3136 monotherapy): Participants must have a tumor that is unresectable or metastatic and for which life prolonging measures do not exist or available therapies are intolerable or no longer effective.
Part 1B (Dose escalation for OP-3136 in combination with fulvestrant): Participants with advanced or metastatic ER+ HER2- breast cancer that have progressed on or after at least 1 prior line of treatment that included endocrine therapy and CDK 4/6 inhibitor in advanced or metastatic setting and must have received no more than 2 prior lines of endocrine therapy (one of which must be in combination with CDK4/6 inhibitor) and no more than 1 prior line of chemotherapy or an antibody-drug conjugate in the advanced or metastatic setting.
Part 1C (Dose escalation for OP-3136 in combination with palazestrant): Participants with advanced or metastatic ER+ HER2- breast cancer that have progressed on or after at least 1 prior line of treatment that included endocrine therapy and CDK 4/6 inhibitor in advanced or metastatic setting and must have received no more than 2 prior lines of endocrine therapy (one of which must be in combination with CDK4/6 inhibitor) and no more than 1 prior line of chemotherapy or an antibody-drug conjugate in the advanced or metastatic setting.
Prior therapy with KAT6A/B inhibitor in any treatment setting.
Participants with advanced/metastatic, symptomatic, visceral spread, that are at risk of life-threatening complications in the short term.
Known active or symptomatic central nervous system (CNS) metastases, carcinomatous meningitis, leptomeningeal disease, or a spinal cord compression that require CNS-specific treatment, or participants who did not demonstrate clinical and radiologic stability during the last 2 months prior to the first dose of study treatment or require or are currently on steroid therapy for CNS metastases.
History of cerebral vascular disease, including transient ischemic attack, within 6 months prior to the first dose of study treatment.
Sequential
OP-3136
DrugSelective inhibitor of HAT enzymes KAT6A and KAT6B
Fulvestrant
DrugSelective estrogen receptor degrader (SERD)
Palazestrant
DrugComplete estrogen receptor antagonist (CERAN)
7
Treatment groupsSee each treatment group below.
Number of participants with dose-limiting toxicities in the Dose Escalation Arms
Incidence of adverse events and laboratory abnormalities
Maximum observed concentration (Cmax)
Time to maximum concentration (Tmax)
Area under the curve from time zero to 24 hours (AUC0-24)
Overall Response Rate (ORR)
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