Aggarwal R, Starzinski S, de Kouchkovsky I, Koshkin V, Bose R, Chou J, Desai A, Kwon D, Kaushal S, Trihy L, Rastogi M, Ippisch R, Aslam M, Friedlander T, Feng F, Oh D, Cheung A, Small E, Evans M, Fong L, and Hope TA
Background: Checkpoint inhibitors have been shown to have limited activity in patients with metastatic castration-resistant prostate cancer. We aimed to determine whether a single dose of lutetium-177 [ 177 Lu]-prostate-specific membrane antigen (PSMA)-617 ( 177 Lu-PSMA-617) followed by maintenance pembrolizumab was safe and could induce durable clinical benefit., Methods: We did an open-label, dose-expansion, phase 1 study at the University of California, San Francisco (San Fransisco, CA, USA). Eligible patients were men aged 18 years or older with progressive metastatic castration-resistant prostate cancer who had an Eastern Cooperative Oncology Group performance status of 0 or 1, had progression on one or more androgen signalling inhibitors, and at least three PSMA-avid lesions on 68 Ga-PSMA-11 positron emission tomography. In part A, patients were enrolled sequentially to one of three schedules in which a single dose of 177 Lu-PSMA-617 (7·4 GBq) was given intravenously 28 days before (schedule 1), concomitant with (schedule 2), or 21 days after (schedule 3) the start of maintenance intravenous pembrolizumab (200 mg every 3 weeks). In part B, 25 patients were enrolled using the recommended phase 2 schedule. The primary endpoint in part A was determination of the recommended phase 2 schedule, and in part B, the objective response rate. The analysis set included all patients who received at least one dose of pembrolizumab or 177 Lu-PSMA-617. This study is registered with ClinicalTrials.gov, NCT03805594., Findings: Between Aug 8, 2019 and May 7, 2022, 43 male patients were enrolled (n=18 part A [six patients per schedule]; n=25 part B), with a median follow-up of 16·5 months (IQR 12·2-21·9). Schedule 1 was selected as the recommended phase 2 schedule for part B, on the basis of safety and feasibility of administration observed in part A. In part B, 14 (56%; 95% CI 35-76) of 25 patients had a confirmed objective response. Two (5%) of 43 patients had a treatment-related adverse event of grade 3 or worse (grade 3 arthritis in schedule 2, grade 3 pneumonitis in schedule 3). One serious adverse event (one death due to aspiration pneumonia) and no treatment-related deaths were observed., Interpretation: A single priming dose of 177 Lu-PSMA-617 followed by pembrolizumab maintenance was safe and had encouraging preliminary activity in patients with metastatic castration-resistant prostate cancer., Funding: Prostate Cancer Foundation, National Cancer Institute, Novartis Pharmaceuticals, and Merck., Competing Interests: Declaration of interests RA reports research grants to their institution from the Prostate Cancer Foundation, National Cancer Institute, Merck, Novartis, Janssen Pharmaceuticals; personal fees from Pfizer, Jubliant Therapeutics, Bayer, Exelixis, Targeted Oncology, Lumanity, EcoR1, Bioexcel, and Amgen; and is a member of the data safety monitoring board for the Prostate Cancer Clinical Trials Consortium/DORA phase 3 trial. TAH reports grants to their institution from Clovis Oncology, Philips, GE Healthcare, Lantheus, the Prostate Cancer Foundation, and the National Cancer Institute (R01CA235741 and R01CA212148); personal fees from Ipsen, Bayer, and BlueEarth Diagnostics; and personal fees from and has an equity interest in RayzeBio and Curium. FYF reports consulting fees from Novartis, Janssen, Bayer, Bristol-Myers Squibb, Sanofi, Roivant, Myovant, Astellas, and Point; serves as an advisor to Artera; and has received research grants from the Prostate Cancer Foundation and the National Cancer Institute (R01CA235741). LF reports research grants from Abbvie, Bavarian Nordic, Bristol-Myers Squibb, Dendreon, Janssen, Merck, and Roche/Genentech; and ownership interests in Actym, Atreca, Bioatla, Bolt, Keyhole, Immunogenesis, Nutcracker, RAPT, Scribe, and Senti, unrelated to this study. JC has received research grants from the Prostate Cancer Foundation, the National Cancer Institute (K08CA273514) and Department of Defense Prostate Cancer Program (W81XWH2010136); and personal fees from Exai Bio, outside the scope of this work. IdK has received research grants to the institution from the Prostate Cancer Foundation and ASCO Conquer Cancer Foundation; and consulting fees from Janssen Pharmaceuticals. VSK reports research grants to their institution from the Prostate Cancer Foundation, Eli Lilly, Merck, Seagen, Endocyte/Novartis, Nektar, Clovis, Janssen, and Taiho. RB reports research grants from the National Cancer Institute (1K08CA226348), Department of Defense, American Cancer Society, Prostate Cancer Foundation, and the UCSF Benioff Institute for Prostate Cancer Research; and received personal fees from Janssen. DYO has received research grants from Prostate Cancer Foundation, National Cancer Institute, Merck, PACT Pharma, the Parker Institute for Cancer Immunotherapy, Poseida Therapeutics, TCR(2) Therapeutics, Roche/Genentech, and Nutcracker Therapeutics; and reimbursement for travel from Roche/Genentech. MJE reports research grants from Prostate Cancer Foundation and the National Cancer Institute; and holds equity in ORIC Pharmaceuticals, Hap10 Bio, Therapaint, and SUBA Pharmaceuticals. All other authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)