The combination of abiraterone acetate and olaparib as first-line therapy for patients with metastatic castration-resistant prostate cancer (mCRPC) prolonged radiographic progression-free survival (rPFS) and improved overall survival (OS) compared to abiraterone acetate plus placebo treatment, according to a randomized, double blind, phase 3 study. 

Noel Clark, MBBS, Salford Royal Hospital, Manchester, UK, presented results from the PROpel trial on Thursday, February 16, 2023, at the 2023 ASCO Genitourinary Cancers Symposium in San Francisco, CA. 

A total of 796 patients with mCRPC who were eligible for abiraterone acetate therapy were enrolled in this study and randomized on a 1-to-1 basis to receive prednisone/prednisolone (5 mg twice daily) with either olaparib (300 mg twice daily) plus either abiraterone acetate (1000 mg once daily) or placebo. Homologous recombination repair (HRR) and BRCA mutation status were assessed after randomized groups were established. As previously reported, the primary endpoint of this study was met, as significant improvement in rPFS was observed in the abiraterone arm when compared to the placebo arm . 

At the data cut-off date of October 12, 2022, the OS rates suggest a consistent trend toward improvement in the abiraterone arm versus the placebo arm, with a median OS of 42.1 months vs 34.7 months, respectively (HR, 0.81, 95% CI; P = .0544). The OS improvement was seen regardless of HRRm status or BRCAm status. 
The most common grade ≥3 adverse event in the abiraterone arm was anemia (16.1%). 

Dr. Clark and co-authors concluded, “These results support the use of [abiraterone acetate plus olaparib] in [first-line] mCRPC.” They also noted, “The median OS of > 42 months is the longest median reported to date in a phase 3 trial in [first-line] mCRPC.”

Source: 

Clark N, Armstrong A, Thiery-Vuillemin, A, et al. Final overall survival (OS) in PROpel: abiraterone (abi) and olaparib (ola) versus abiraterone and placebo (pbo) as first-line (1L) therapy for metastatic castration-resistant prostate cancer (mCRPC). Presented at 2023 ASCO Genitourinary Cancers Symposium; February 17-19; San Francisco, CA. Abstract LBA16.