5059 Background: Epothilones comprise a new class of microtubule stabilizing agents, and sagopilone is a novel, fully synthetic epothilone that has shown significant activity against a broad range of tumor models.
METHODS
Chemotherapy-naïve metastatic CRPC patients received sagopilone 16 mg/m2 IV over 3 hours every 21 days and prednisone 5 mg PO BID. The primary efficacy evaluation was based on PSA decline (≥50% PSA reduction confirmed at least 28 days apart). The Simon 2-Stage design required 3 responders among the first 13 evaluable patients and 13 responders among the first 46 evaluable patients to declare the agent of interest for further investigation.
RESULTS
Between August 2006 and May 2008, 53 patients were enrolled and treated. Sites of metastases were: bones, lymph nodes, and viscera in 72%, 68%, and 25% patients, respectively. Median PSA was 107.5 (6.2-1727) ng/ml. A median of 5 (2-12) cycles were delivered. The median dose delivered per cycle was 13.3 mg/m2. Two patients did not meet all eligibility criteria and were excluded from efficacy analyses; 3 additional patients were excluded from PSA decline and progression-free survival analyses due to missing baseline PSA assessment. Twenty of 48 patients (42%; 80% CI: 32%-52%) had a confirmed PSA decline in excess of 50% and 30 (63%; 95% CI: 47%-76%) had a 30% reduction in PSA within 3 months of enrollment. Of 39 patients with measurable disease by RECIST, 1 had a complete, 9 had a partial confirmed response (26%; 95% CI: 13%-42%). The median PFS was 6.4 months (95% CI: 4.7 to 10.2). All 53 patients are evaluable for safety. Toxicities occurring in ≥ 20% patients included peripheral neuropathy 74% (19% grade 3), fatigue 40% (6% grade 3, 2% grade 4), extremity pain 36% (6% grade 3), arthralgia 23% (no grade 3, 4), and constipation 21% (no grade 3, 4).
CONCLUSIONS
Sagopilone is active in metastatic chemotherapy-naïve CRPC patients, with probability of PSA decline, measurable disease responses, and PFS approximating the current standard of docetaxel + prednisone. Neuropathy and fatigue are the most common toxicities, while hematologic toxicity is rare. Further evaluation of this agent in prostate cancer is warranted. [Table: see text].