Continuing cabazitaxel beyond 10 cycles for metastatic castrate-resistant prostate cancer

Aim: Cabazitaxel prolongs survival in patients with metastatic castration-resistant prostate cancer in the postdocetaxel setting. We investigate the benefit of continuing cabazitaxel beyond 10 cycles in patients who are clinically responding without significant toxicity. Methods: A comparison was made between patients who received cabazitaxel for >10 cycles and those who had ≤10 cycles. Overall survival (OS), prostate-specific antigen (PSA) response, alkaline phosphatase (ALP) changes and treatment-associated adverse events were evaluated. Results: The median OS was 9 months (range 0.75-59), with OS significantly higher in patients who received extended duration of treatment: 14 months (range 3-90) vs 7 months (range 1.3-21) in patients treated with 4-10 cycles (HR 0.28, 95% CI 0.1 to 0.74, p=0.01). PSA decline did not show a significant correlation with OS (PSA decline ≥50%, p=0.54). Furthermore, there was no significant difference in OS between patients who had a normal versus high ALP at baseline. There was no clear evidence of cumulative toxicity in those having >10 cycles. Conclusion: A substantial proportion of patients with metastatic castration-resistant prostate cancer were able to receive more than 10 cycles of cabazitaxel without clinically relevant cumulative toxicity.