American Association for Cancer Research
10780432ccr204528-sup-254612_2_supp_7001670_qqdflj.docx (22.62 kB)

Supplementary Table 1 from Phase I Study of MEDI3726: A Prostate-Specific Membrane Antigen-Targeted Antibody–Drug Conjugate, in Patients with mCRPC after Failure of Abiraterone or Enzalutamide

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journal contribution
posted on 2023-03-31, 22:48 authored by Johann S. de Bono, Mark T. Fleming, Judy S. Wang, Richard Cathomas, Manuel Selvi Miralles, John Bothos, Mary Jane Hinrichs, Qu Zhang, Peng He, Marna Williams, Anton I. Rosenbaum, Meina Liang, Kapil Vashisht, Song Cho, Pablo Martinez, Daniel P. Petrylak

Clinical antitumor activity summary



MEDI3726 is an antibody–drug conjugate targeting the prostate-specific membrane antigen and carrying a pyrrolobenzodiazepine warhead. This phase I study evaluated MEDI3726 monotherapy in patients with metastatic castration-resistant prostate cancer after disease progression on abiraterone and/or enzalutamide and taxane-based chemotherapy. MEDI3726 was administered at 0.015–0.3 mg/kg intravenously every 3 weeks until disease progression/unacceptable toxicity. The primary objective was to assess safety, dose-limiting toxicities (DLT), and MTD/maximum administered dose (MAD). Secondary objectives included assessment of antitumor activity, pharmacokinetics, and immunogenicity. The main efficacy endpoint was composite response, defined as confirmed response by RECIST v1.1, and/or PSA decrease of ≥50% after ≥12 weeks, and/or decrease from ≥5 to <5 circulating tumor cells/7.5 mL blood. Between February 1, 2017 and November 13, 2019, 33 patients received MEDI3726. By the data cutoff (January 17, 2020), treatment-related adverse events (TRAE) occurred in 30 patients (90.9%), primarily skin toxicities and effusions. Grade 3/4 TRAEs occurred in 15 patients (45.5%). Eleven patients (33.3%) discontinued because of TRAEs. There were no treatment-related deaths. One patient receiving 0.3 mg/kg had a DLT of grade 3 thrombocytopenia. The MTD was not identified; the MAD was 0.3 mg/kg. The composite response rate was 4/33 (12.1%). MEDI3726 had nonlinear pharmacokinetics with a short half-life (0.3–1.8 days). The prevalence of antidrug antibodies was 3/32 (9.4%), and the incidence was 13/32 (40.6%). Following dose escalation, no MTD was identified. Clinical responses occurred at higher doses, but were not durable as patients had to discontinue treatment due to TRAEs.

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