Study of JANX014 in Subjects With Metastatic Castration-Resistant Prostate Cancer

Inclusion Criteria: * Male ≥18 years of age at the time of signing informed consent * Histologically or cytologically confirmed adenocarcinoma of the prostate * For Dose Escalation: Having mCRPC that progressed after at least one novel anti-androgen therapy and at least one taxane containing regimen. Participants who have actively refused a taxane containing regimen or are medically unsuitable to receive taxane are eligible. * Adequate organ function * For Dose Expansion Part: Have received ≤ 2 anti-androgen therapies in either the HSPC or CRPC setting and no more than 1 prior taxane regimen in the HSPC setting. Participants who have actively refused a taxane regimen or are medically unsuitable to receive taxane are eligible. Exclusion Criteria: * Prior solid organ transplant * Prior treatment with any CAR-T cell therapy, approved or investigational T-cell engager therapy, and prior receipt of radioligand therapy * Clinically significant cardiovascular disease