Prostate Cancer Coverage from Every Angle

Early-Phase Study of Antibody-Drug Conjugate in Castration-Resistant Prostate Cancer

By: Kayci Reyer
Posted: Monday, January 20, 2020

According to early-stage research findings published in the Journal of Clinical Oncology, DSTP3086S, a antibody-drug conjugate that targets six-transmembrane epithelial antigen of prostate 1 (STEAP1), may result in a clinical benefit for patients with metastatic castration-resistant prostate cancer. With an acceptable safety profile and evidence of antitumor activity, this agent requires optimization for further clinical development.

“Targeting STEAP1-expressing [metastatic castration-resistant prostate] tumors with an [antibody-drug conjugate] is feasible,” concluded Daniel C. Danila, MD, of Memorial Sloan Kettering Cancer Center, and colleagues.

The phase I, 3 + 3 dose-escalation study included 84 patients, 77 of whom received 0.3 to 2.8 mg/kg of intravenous DSTP3086S every 3 weeks and 7 of whom received 0.8 to 1.0 mg/kg of intravenous DSTP3086S each week. Clinical activity was noted, including a reduction of at least 50% in prostate-specific antigen for 11 of the 62 patients (18%) who received more than 2 mg/kg of DSTP3086S every 3 weeks. Among the 36 patients with measurable baseline disease, 2 (6%) achieved a partial response, and 16 of the 27 patients (59%) with unfavorable baseline levels of circulating tumor cells experienced a conversion to favorable levels of circulating tumor cells. The group undergoing weekly treatment did not experience  responses as determined by prostate-specific antigen or Response Evaluation Criteria in Solid Tumors criteria.

Dose-limiting toxicities were experienced in both treatment groups, including grade 3 transaminitis in two patients receiving treatment every 3 weeks and grade 3 hyperglycemia and grade 4 hypophosphatemia in one patient undergoing weekly treatment. Adverse events occurring in more than 20% of overall patients included fatigue, peripheral neuropathy, and gastrointestinal issues. Via initial expansion during dose escalation, 10 patients received 2.8 mg/kg every 3 weeks, but a dose reduction to 2.4 mg/kg (n = 39) occurred following frequent dose reductions.

 Disclosure: For full disclosures of the study authors, visit

By continuing to browse this site you permit us and our partners to place identification cookies on your browser and agree to our use of cookies to identify you for marketing. Read our Privacy Policy to learn more.