A Study of Mevrometostat With Enzalutamide in People With Prostate Cancer Who Have Previously Received Androgen Receptor Pathway Inhibitor Therapy

Inclusion Criteria: * Willing and able to provide written informed consent * Age 18 years or older * Diagnosis of prostate cancer (adenocarcinoma) confirmed by tissue sample, without neuroendocrine or small cell features * Currently taking or recently treated with enzalutamide, darolutamide, or apalutamide (within 30 days of screening) and willing to switch to or restart enzalutamide for this study * Cancer has spread to bone or soft tissue (metastatic disease), confirmed by imaging * ECOG performance status of 0, 1, or 2 (able to care for self and up and about more than 50% of waking hours) * Testosterone level less than 50 ng/dL at screening, with ongoing hormone deprivation therapy or prior surgical castration * If receiving bone-protective therapy (e.g., denosumab or bisphosphonates), must be on a stable dose for at least 4 weeks * Evidence of cancer progression while on enzalutamide, darolutamide, or apalutamide, shown by rising PSA, worsening disease on imaging, or new bone lesions * Adequate organ function based on blood tests within 28 days of starting treatment, including adequate blood counts, kidney function, and liver function * Willing to use acceptable birth control during the study and for 30 days after the last dose Exclusion Criteria: * History of myelodysplastic syndrome, acute myeloid leukemia, or other prior cancer (exceptions: non-melanoma skin cancer, carcinoma in situ, cancers more than 3 years ago with no recurrence, or early-stage cancers with low …