Prostate-specific Membrane Antigen Antibody-Drug Conjugate (PSMA ADC) 1301 is an open-label, dose-escalation phase 1 study of PSMA ADC administered IV in subjects with progressive, castration-resistant, metastatic prostate cancer that has progressed after prior taxane therapy. For all subjects, PSMA ADC will be administered in four repeating cycles.

Inclusion Criteria:

1. A diagnosis of progressive, castration-resistant, metastatic prostate cancer.
2. Prior chemotherapy regimens, one of which contains taxane.
3. Eastern Cooperative Oncology Group status of 0 or 1

Exclusion Criteria:

1. Clinically significant cardiac disease or severe debilitation pulmonary disease
2. Evidence of an active infection requiring ongoing antibiotic therapy
3. Any prior treatment with any other therapy targeting PSMA
4. History of drug and/or alcohol abuse