Progenics Pharmaceuticals reported positive clinical data from a completed phase 1 study of PSMA ADC, an antibody-drug conjugate designed to selectively deliver chemotherapy to cells that express prostate-specific membrane antigen. PSMA ADC was generally well tolerated in patients at doses up to and including 2.5 mg/kg, the maximum tolerated dose. Findings were presented at the 2013 Genitourinary Cancers Symposium, a meeting co-sponsored by the American Society of Clinical Oncology, the American Society for Radiation Oncology and the Society of Urologic Oncology. Fifty-two patients with metastatic castration-resistant prostate cancer were dosed at nine dose levels. Significant antitumor activity was observed across doses ranging from 1.8 mg/kg to 2.8 mg/kg. Dose limiting toxicities, primarily neutropenia, were seen at 2.8 mg/kg. The most commonly reported adverse events were anorexia and fatigue. Progenics opened enrollment in a subsequent phase 2 study of PSMA ADC in September 2012. This ongoing trial is an open-label, multicenter study assessing the anti-tumor activity and tolerability of PSMA ADC in up to 75 subjects with mCRPC. Patients are receiving a total of eight doses of drug at 2.5 mg/kg. The study endpoints evaluate responses in prostate specific antigen; circulating tumor cells; pain; and change in tumor size as measured under RECIST criteria. Safety also is being evaluated.