High response to docetaxel (D)/carboplatin (C) based chemotherapy as salvage therapy in patients with docetaxel-resistant metastastic hormone-refractory prostate cancer (HRPC)

Abstract

e16041 Background: Presently, there is no standard treatment for prostate cancer (PC) patients who are resistant to docetaxel therapy. While previous reports support the use of C in combination with D in these patients (pts), the optimal regime is still unknown. Methods: Metastatic HRPC pts with clinical and/or radiographic evidence of progression while on docetaxel were included in our retrospective analysis. Between February 2005 and December 2008, 30 pts received treatment with C AUC 5 q3wks in combination with D 75 mg/m2 q3wks or D 35 mg/m2 d1, d8, d15 q4wks. All pts were assessed for PSA response and clinical outcome. Results: 27 pts were evaluable for response. Median age was 69 years (range 56–77) and median baseline performance status was ECOG 1 (range 0–2). The median number of prior therapies was 1 (range 1–3) with a median of 7 cycles of D therapy (range 3–34) administered. Median PSA at baseline was 297.15 ng/ml (range 12.33–6,446). Serum chromogranin A and neuron-specific enolase (NSE) were elevated in 24/24 and 8/25 cases, respectively. The median follow-up was 8.9 months (range: 0–38) with a median number of 6 cycles DC administered (range: 2–35). PSA declines of ≥50% (= PSA-response) was achieved in 14 of 27 pts (52%, 95% C.I. 0.32, 0.71) and PSA stabilization in 9 pts (33%). 4 pts (15%) progressed without PSA response. 6 PSA responders had a PSA reduction of >90%. The median duration of PSA response was 20.7 wks (95% C.I. 18.4, 59 wks). TTP was significantly longer in PSA responders vs. PSA non-responders (64.7 wks vs 15 wks, p<0.0001). 10 of 16 pts with measureable disease were evaluable for response. 3 of 6 PSA responders had a PR and 3 SD, while 2/4 pts with PSA non-response had PD and 2 SD. At the time of analysis, 2 PSA responders and 7 PSA non-responders have died. Median OS of all patients was 69.7 weeks with 79.9 wks for PSA responders vs. 38 wks for PSA non-responders (p=0.0034). The most common grade 3/4 toxicities were neutropenia in 42%, anemia in 23% and thrombocytopenia in 15% of pts. 17 of 30 pts had blood transfusions due to anemia. Conclusions: This retrospective analysis supports the usefulness of C plus weekly D chemotherapy as ≥second-line chemotherapy in docetaxel-resistant PC patients. No significant financial relationships to disclose.