Gefitinib (G) plus prednisone (P) versus placebo (pl) plus prednisone in the treatment of hormone-refractory prostate cancer (HRPC): A randomized phase II trial

Abstract

5070 Background: In spite of EGF-R overexpression in 40%-80% of pts with HRPC, the results achieved so far with G, a selective EGF-R tyrosine kinase inhibitor have been dismal. This trial was designed to investigate the activity of G when combined with P, a common therapeutic option for HRPC pts. Methods: HRPC pts unresponsive to antiandrogen withdrawal were given P (10 mg/d) plus G (250 mg/d) or pl. On progression, pts initially assigned to pl were offered the possibility to receive G. This was a one-stage trial, and 37 pts per arm were required. Best PSA response (any decrease = 50% in baseline PSA confirmed 4 wks apart) was the primary end-point. Time to disease progression, OS and toxicity were secondary end-points. Results: 82 pts were enrolled (GP: 38; plP: 44). Groups were well balanced in respect to median age (75 vs 74 yrs); WHO PS (0 in both); baseline PSA (52 vs 44 ng/ml); bone disease (87% vs 84%) Gleason score 7 (58% vs 52%); prior treatment. At a median follow-up time of 29 mos (26–32), overall 77 pts progression and 51 died. PSA resp was recorded in 16% and 11% of pts in GP and plP groups. Median time to progression was 4.0 (3.5–4.5) and 4.5 (3.5–5.0) mos, respectively. In both groups, median PSA level increased during the first 8 wks of treatment (GP:13%; plP: 32%) while it decreased thereafter. Median time to death was 26.5 (16–37) and 20.5 (14–27) mos in the GP and plP groups, respectively (HR: 0.69, 0.39–1.23; p=.2). However, OS of pts given either early or delayed treatment with G was significantly longer (26.5 vs 17.5 mos; HR: 0.49, 0.28–0.87, p=.01). This advantage was maintained also after multivariate analysis by Gleason score, baseline PSA, Hb and PAL, WHO PS and pain score. AEs (any grade) occurred in 19 pts in each arm. However diarrhea and skin rash were more common in the GP group (12% vs 0% and 14% vs 2%, respectively). Conclusions: G when combined to P showed a moderate toxicity, achieved PSA control and prolonged pts survival. The efficacy of GP in HRPC warrants to be further investigated. [Table: see text] No significant financial relationships to disclose.