Neoadjuvant trial of sunitinib malate and androgen ablation (ADT) in patients with localized prostate cancer (PCa) at high risk for recurrence.

Abstract

143 Background: Presurgical ADT does not improve long-term outcomes in patients (pts) with high-risk localized PCa. Since the VEGF and PDGF signaling pathways have been implicated in PCa progression, and ADT results in endothelial cell apoptosis in the prostate by a VEGF-mediated mechanism, we hypothesized that combined treatment with sunitinib malate (SU), an oral inhibitor of the tyrosine kinases of VEGFR and PDGFR, might improve the efficacy of ADT in this pt population. Methods: Pts with no radiological evidence of metastases and either PCa ≥ clinical (c)T3 disease or Gleason grade 8-10 or serum prostate-specific antigen (PSA) ≥ 20 ng/mL or cT2b-c and Gleason 7 and PSA ≥10 ng/mL (AJCC, 1992), received i.m. leuprolide and oral SU for three 30-day cycles followed by surgery. SU was administered continuously at 37.5 mg daily (25 mg daily in the initial 6 pts). The primary endpoint of this phase II trial was rate of pathologic complete response (pCR). Secondary endpoints included safety and time to progression (TTP). Unresectable pelvic nodal disease, confirmed post-operative PSA ≥ 0.2 ng/mL, or administration of post-operative radiation or ADT, defined treatment failure. Results: Forty-four pts completed accrual, with a median age of 58 years (range 47-72); 34 Caucasian, 5 African-American, 4 Hispanic, and 1 Indian. High-risk criteria included cT3 (24/44), Gleason 8-10 (30/44), PSA ≥ 20 ng/mL (16/44). Two men were ineligible/declined therapy and one postponed surgery. No grade 4 toxicities or related discontinuations were observed. Thirty-five pts completed 3 months on 37.5 mg daily SU plus ADT and surgery with no unexpected complications. Of these, 2 pts experienced a pCR. Twenty (57%) pts have failed treatment or died, with a median TTP 27 months (95% CI: 12 – not estimable). The median follow-up of the remaining event-free pts is 35 months (range 23-41). Conclusions: The 3-months preoperative combination of SU and ADT is safe and well tolerated in pts with high-risk primary PCa. We observed 2 complete remissions in 35 patients. Ongoing characterization of molecular changes in the epithelial and stromal compartments will help understand the mechanisms of SU activity in PCa. [Table: see text]