Carboplatin in Metastatic Castrate Resistant Prostate Cancer: A Retrospective Study of Heavily Pretreated Patients (COMPACT)

Introduction: Many clinicians consider carboplatin monotherapy in advanced castrate-resistant prostate cancer (CRPC) patients who have progressed through all available hormonal and standard chemotherapy treatment options, despite the limited evidence to justify its use. Patients and Methods: This retrospective analysis aimed to evaluate the use of carboplatin monotherapy in patients with refractory prostate cancer in Australia. Efficacy (PSA response, duration, and survival) as well as toxicity was evaluated. Demographic data, PSA response rates, survival data and details of carboplatin treatment protocols, including dose and duration, were collected. Exploratory analyses were conducted on potential prognostic factors. Results: Fifty-one patients received carboplatin: median age 68 (range 55-86 years). Most patients (78.3%) received carboplatin AUC 5 at 3-week intervals. The median number of cycles of carboplatin received was 3 (range 1-17). The median duration of treatment was 63 days (range 1-441). The median overall survival was 6.8 months. Six (11.8%) patients had a PSA response ≥ 50%. The median time to PSA progression on carboplatin, as defined by PCWG,² was 67 days (range 15-418). Sixteen patients (31%) required dose delays or reductions and 8 patients (15.6%) ceased carboplatin due to treatment toxicity. Conclusion: Carboplatin is often used in Australia once all available standard treatment options have been exhausted in patients with CRPC. Toxicity is mild, and a minority of patients have responses, but these responses are rarely durable.