Results of a phase II study of sunitinib (SU) maintenance after response to docetaxel in metastatic castration-resistant prostate cancer (mCRPC).

153 Background: Docetaxel (D) remains the standard first cytotoxic therapy in mCRPC. Given its mechanism of action, acceptable toxicity profile and simple administration, SU had potential as maintenance therapy for mCRPC. In this multicenter study, we evaluated the tolerability and efficacy of SU monotherapy in patients (pts) with mCRPC who have responded to D. Methods: Pts withmCRPC and responding/stable disease at the time of D completion were enrolled in this multicentre trial. Pts received 50mg of SU daily on 4/2 week on/off cycles. The primary endpoint was progression-free survival (PFS), defined on the basis of RECIST criteria and worsening disease-related symptoms requiring further therapy. Because the effect of SU on PSA is not well known, PSA progression alone was not considered disease progression. PFS of 180 days was considered to be a clinically meaningful threshold for recommending further study of SU. PSA response was a secondary endpoint. The threshold for PSA-progression (PSA-P) was define...