The following is a summary of “Randomized Phase II Multicenter Trial of Abiraterone Acetate With or Without Cabazitaxel in the Treatment of Metastatic Castration-Resistant Prostate Cancer,” published in the November 2023 issue of Oncology by Slovin, et al.

For a phase II randomized noncomparative trial, researchers sought to evaluate the safety and efficacy of abiraterone acetate/prednisone (AAP) alone or in combination with cabazitaxel (AAP + C) in 81 men with metastatic castration-resistant prostate cancer (mCRPC). The objective was to assess radiographic progression-free survival (rPFS), prostate-specific antigen (PSA) progression-free survival, overall objective response, and safety outcomes while exploring the correlation between RB status and circulating tumor cells (CTC)

Patients were equally divided into two arms, one receiving AAP followed by cabazitaxel upon progression (Arm 1) and the other receiving upfront treatment with AAP + C (Arm 2). The trial investigated real-time assessment of RB status and CTC analysis to correlate with clinical outcomes.

Both treatment arms demonstrated good tolerability. In Arm 1, the median rPFS for AAP was 6.4 months (95% CI, 3.8 to 10.6), with a median overall survival (OS) of 18.3 months (95% CI, 14.4 to 37.6). Fifty-six percent of patients exhibited a ≥50% decline in PSA. In Arm 2, the median rPFS for AAP + C was extended to 14.8 months (95% CI, 10.6 to 16.4), with a median OS of 24.5 months (95% CI, 20.4 to 35.0). Notably, 92.1% of patients in this arm showed a ≥50% decline in PSA. RB expression in pretherapy tumor biopsy, CTC, or tissue explants did not identify those benefiting from AAP + C.

AAP + C was well-tolerated and demonstrated improved rPFS, prolonged OS, and a higher proportion of PSA declines than AAP alone, suggesting potential benefits when administered upfront. Further research was warranted to identify the specific population that may derive optimal benefits from this combination.

Source: ascopubs.org/doi/full/10.1200/JCO.22.02639