A randomized phase II study of cediranib (CED) alone versus CED plus dasatinib (DAS) in patients (pts) with castration-resistant prostate cancer (CRPC).

5039 Background: Activation of the Vascular Endothelial Growth Factor Receptor (VEGFR) and the oncogenic Src pathway has been implicated in the development of CRPC in preclinical models. CED and DAS are multi-kinase inhibitors targeting VEGFR and Src respectively. Phase II studies of CED (Karakunnel et al ASCO 2009) and DAS (Yu et al Urology 2011) in CRPC have shown single agent activity. Methods: Docetaxel-preteated CRPC pts were randomized to arm A: CED alone (20 mg/day) vs arm B: CED (20 mg/day) plus DAS (100 mg/day) given orally on 4-week cycles. Primary endpoint was 12 week progression-free survival (PFS) as per the Prostate Cancer Clinical Trials Working Group (PCWG2). Patient reported outcomes were evaluated using Functional Assessment of Cancer Therapy-Prostate (FACT-P) and Present Pain Intensity (PPI) scales. Correlative studies of bone turnover markers (BTM), including bone alkaline phosphate (BAP) and serum beta-C telopeptide (B-CTx) were serially assayed. Results: 22 patients, 11 per arm, were enrolled. Baseline demographics were similar in both arms. Median number of cycles = 4 in arm A (range 1-12) and 2 in arm B (range 1-9). Twelve-week PFS was 73 % in arm A vs 18 % in arm B (p = 0.03). Median PFS in months (arm A vs B) was: 5.2 vs 2.6 (95% CI: 1.9-6.5 vs 1.4-not reached). Most common grade 3 toxicities were hypertension, anemia and thrombocytopenia in arm A and hypertension, diarrhea and fatigue in arm B. One treatment-related death (retroperitoneal hemorrhage) was seen in arm A. FACT-P and PPI scores did not significantly change in either arm. No correlation between BTM and PFS was seen in both arms A and B. Conclusions: Although limited by small numbers, this randomized study showed that the combination of VEGFR and Src targeted therapy did not result in improved efficacy and may be associated with a worse outcome than VEGFR targeted therapy alone in pts with CRPC. Clinical trial information: NCT01260688.