TheraP: 177Lu-PSMA-617 (LuPSMA) versus cabazitaxel in metastatic castration-resistant prostate cancer (mCRPC) progressing after docetaxel—Overall survival after median follow-up of 3 years (ANZUP 1603).

Authors

Michael Hofman

Michael S Hofman

Peter MacCallum Cancer Centre and Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, Australia

Michael S Hofman , Louise Emmett , Shahneen Sandhu , Amir Iravani , Anthony M. Joshua , Jeffrey C. Goh , David A. Pattison , Thean Hsiang Tan , Ian D. Kirkwood , Roslyn J. Francis , Craig Gedye , Natalie K. Rutherford , Alison Yan Zhang , Margaret Mary McJannett , Martin R. Stockler , Scott Williams , Andrew James Martin , Ian D. Davis

Organizations

Peter MacCallum Cancer Centre and Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, Australia, Department of Theranostics and Nuclear Medicine, St. Vincent's Hospital, Sydney, NSW, Australia, Peter MacCallum Cancer Center, Melbourne, Australia, Princess Margaret Cancer Center, University Health Network, University of Toronto, Toronto, ON, Canada, Department of Oncology, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia, Royal Adelaide Hospital, Adelaide, Australia, Sir Charles Gairdner Hospital, Perth, Australia, Calvary Mater Newcastle, Waratah, NSW, Australia, Calvary Mater Newcastle, Newcastle, Australia, Chris O'Brien Lifehouse, Sydney, Australia, Australian and New Zealand Urogenital and Prostate Cancer Trials Group, Camperdown, NSW, Australia, NHMRC Clinical Trials Centre, University of Sydney, Sydney, NSW, Australia, NHMRC Clinical Trials Center, University of Sydney, Sydney, Australia, Eastern Health Clinical School, Monash University, Box Hill, VIC, Australia

Research Funding

Other
Other Government Agency, Australian Nuclear Science and Technology Organisation (ANSTO), Endocyte (now part of Advanced Accelerator Applications, now the Radioligand business of Novartis), Its a Bloke Thing, Movember and CAN4CANCER

Background: We previously reported that in men with mCRPC progressing after docetaxel randomly assigned LuPSMA vs. cabazitaxel (Lancet 2021), those assigned LuPSMA has significant improvements in PSA response rate (66% vs. 37%), RECIST response rate (49% vs. 24%), progression-free survival (HR 0.63), less G3-4 toxicities (33% vs. 53%) and better patient-reported outcomes. We now report the secondary endpoint of overall survival (OS) with mature follow-up, for trial participants, and also those initially excluded because of low PSMA-expression or discordant disease on imaging with PSMA-PET and FDG-PET. Methods: Eligibility for the TheraP trial required mCRPC progressing after docetaxel, PET imaging with 68Ga-PSMA-11 that showed high PSMA-expression (at least one site with SUVmax≥20), and 18F-FDG demonstrating no sites of disease of FDG-positive and PSMA-negative (discordant disease). Participants were randomly assigned treatment with LuPSMA (8.5-6GBq every 6 weeks, maximum 6 cycles) vs cabazitaxel (20mg/m2 every 3 weeks, maximum 10 cycles). OS was analyzed by intention-to-treat and summarized by restricted mean survival time (RMST) to account for non-proportional hazards. Results: 291 patients were screened from 6 Feb 2018 to 3 Sep 2019: 200 were eligible and randomly assigned LuPSMA (99) or cabazitaxel (101); 80 of 291 (27%) registered after initial eligibility were excluded after PSMA/FDG-PET(51 SUVmax < 20, 29 discordant), with follow-up available in 61 of the 80 (76%). After a median follow-up time of 36 months (data cut-off 31 Dec 2021), death was reported in 70/101 assigned cabazitaxel, 77/99 assigned LuPSMA, and 55/61 excluded after PSMA/FDG-PET. Subsequent treatments among those assigned cabazitaxel included cabazitaxel in 21, and LuPSMA in 20; and among those assigned LuPSMA included additional LuPSMA in 5, and cabazitaxel in 32. Overall survival was similar in those randomly assigned LuPSMA versus cabazitaxel (RMST to 36 months was 19.1 vs. 19.6 months, difference -0.5, 95% CI -3.7 to + 2.7). No additional safety signals were identified with longer follow-up. Among 61 men excluded by imaging with PSMA/FDG-PET before randomisation, RMST to 36 months was 11.0 months (95% CI 9.0 to 13.1), following treatment that included cabazitaxel in 29 (48%) and LuPSMA in 3 (5%). Conclusions: LuPSMA is a suitable option for men with mCRPC progressing after docetaxel, with lower adverse events, higher response rates, improved patient-reported outcomes, and similar OS compared with cabazitaxel. Median survival was considerably shorter for patients excluded on PSMA/FDG-PET due to either low PSMA expression or FDG-discordant disease who would otherwise be eligible for LuPSMA. Clinical trial information: NCT03392428.

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Abstract Details

Meeting

2022 ASCO Annual Meeting

Session Type

Oral Abstract Session

Session Title

Genitourinary Cancer—Prostate, Testicular, and Penile

Track

Genitourinary Cancer—Prostate, Testicular, and Penile

Sub Track

Prostate Cancer– Advanced/Castrate-Resistant

Clinical Trial Registration Number

NCT03392428

Citation

J Clin Oncol 40, 2022 (suppl 16; abstr 5000)

DOI

10.1200/JCO.2022.40.16_suppl.5000

Abstract #

5000

Abstract Disclosures