Randomized Phase II Multicenter Trial of Abiraterone Acetate with or Without Cabazitaxel in the Treatment of Metastatic Castration-Resistant Prostate Cancer

Susan F. Slovin*, Karen Knudsen, Susan Halabi, Renee De Leeuw, Ayesha Shafi, Praneet Kang, Steven Wolf, Bin Luo, Anuradha Gopalan, Tracy Curley, Mark Fleming, Ana Molina, Celina Fernandez, Kevin Kelly

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

PURPOSEImproving clinical outcomes with novel drug combinations to treat metastatic castration-resistant prostate cancer (mCRPC) is challenging. Preclinical studies showed cabazitaxel had superior antitumor efficacy compared with docetaxel. Gene expression profiling revealed divergent effects of these taxanes in cycling cells. mCRPC are RB deficient rendering them hypersensitive to taxanes. These data suggested that upfront treatment with cabazitaxel with abiraterone may affect therapeutic response. We designed a phase II randomized noncomparative trial of abiraterone acetate/prednisone (AAP) or AAP and cabazitaxel (AAP + C) in men with mCRPC to address this hypothesis.METHODSThis trial of 81 men with mCRPC determined the radiographic progression-free survival (rPFS), prostate-specific antigen (PSA) progression-free survival, overall objective response, and safety of AAP or AAP + C. Equally allocated patients received AAP followed by switching to cabazitaxel upon radiographic progression (arm 1) or upfront with AAP + C (arm 2). Patients were stratified into high-/low-risk groups by the Halabi nomogram. Real-time assessment of RB status and circulating tumor cell (CTC) analysis to correlate with clinical outcomes was exploratory.RESULTSBoth treatment arms were well-tolerated. Median rPFS in AAP was 6.4 months (95% CI, 3.8 to 10.6) and median overall survival (OS) 18.3 months (95% CI, 14.4 to 37.6), respectively. Fifty-six percent of patients showed â ‰¥50% decline in PSA. Median rPFS in AAP + C was 14.8 months (95% CI, 10.6 to 16.4), and median OS 24.5 months (95% CI, 20.4 to 35.0). There was a â ‰¥50% decline in PSA in 92.1% of men. Neither RB expression in pretherapy tumor biopsy, CTC, or tissue explants identified those who may benefit from AAP + C.CONCLUSIONAAP + C was safe with improved rPFS, OS duration, and a higher proportion of PSA declines. This suggests that AAP + C given earlier rather than sequentially may benefit some men. Further work is needed to identify this population.

Original languageEnglish
Pages (from-to)5015-5024
Number of pages10
JournalJournal of Clinical Oncology
Volume41
Issue number32
DOIs
StatePublished - 10 Nov 2023
Externally publishedYes

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