ARX517/JNJ-95298177 as Monotherapy or Combination Therapy in Subjects With Metastatic Prostate Cancer

Key Inclusion Criteria: * Male and ≥18 years at the time of providing written informed consent. * Histologically confirmed prostate adenocarcinoma. * For subjects who have not undergone an orchiectomy, must be undergoing treatment with a luteinizing hormone-releasing hormone (LHRH) agonist or antagonist and must agree to continue such therapy while on study treatment. Subjects enrolled to mCRPC cohorts must have serum testosterone levels of ≤50ng/dL (1.73nM at Screening). * Must receive prior treatment(s) as defined in the protocol for each cohort * Documented evidence of disease progression on or after the most-recent prior regimen for mCRPC cohorts * mCSPC combination cohorts: High volume metastatic disease documented by CT/MRI and/or 99mTC bone scan (for bone lesions) * Adequate blood counts * Must have at least 1 PSMA-positive metastatic lesion and no measurable PSMA-negative lesions by local assessment for alternative dosing regimen and combination cohorts. Key Exclusion Criteria * Receipt of chemotherapy within 21 days prior to enrollment; hormonal therapy (not including LHRH analogs) within 7 days prior to enrollment; palliative radiation therapy within 7 days prior to enrollment; or any other anticancer therapy within 21 days prior to enrollment or other therapy for monotherapy cohorts * Receipt of more than 1 prior taxane regimen or non-taxane chemotherapy for prostate cancer for alternative dose regimen and mCRPC combination cohorts * Receipt prior apalutamide, e…