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Phase II randomized study of figitumumab plus docetaxel and docetaxel alone with crossover for metastatic castration-resistant prostate cancer
J.S. De Bono, J.M. Piulats, H.S. Pandha, D.P. Petrylak, F. Saad, L.M.A. Aparicio, S.K. Sandhu, P. Fong, S. Gillessen, G.R. Hudes T. Wang, J. Scranton, and M.N. Pollak
Clinical Cancer Research, Volume 20, Issue 7, 1 April 2014, Pages 1925-1934
Figitumumab is a human IgG2 monoclonal antibody targeting insulin-like growth factor 1 receptor (IGF-1R), with antitumor activity in prostate cancer. This phase II trial randomized chemotherapy- naïve men with progressing castration-resistant prostate cancer to receive figitumumab every 3 weeks with docetaxel/prednisone (Arm A) or docetaxel/prednisone alone (Arm B1). At progression on Arm B1, patients could cross over to the combination (Arm B2).
Prostate-specific antigen (PSA) response was the primary endpoint; response assessment on the two arms was noncomparative and tested separately; H0 = 0.45 versus HA = 0.60 ( α = 0.05; β = 0.09) for Arm A; H0 = 0.05 versus HA = 0.20 (α = 0.05, β = 0.10) for Arm B2. A comparison of progression-free survival (PFS) on Arms A and B1 was planned.
A total of 204 patients were randomized and 199 treated (Arm A: 97; Arm B1: 102); 37 patients crossed over to Arm B2 (median number of cycles started: Arm A = 8; B1 = 8; B2 = 4). PSA responses occurred in 52% and 60% of Arms A and B1, respectively; the primary PSA response objective in Arm A was not met. Median PFS was 4.9 and 7.9 months, respectively (HR = 1.44;95%confidence interval, 1.06-1.96). PSA response rate was 28% in Arm B2. The figitumumab combination appeared more toxic, with more treatment-related grade 3/4 adverse events (75% vs. 56%), particularly hyperglycemia, diarrhea, and asthenia, as well as treatment-related serious adverse events (41% vs. 15%), and all-causality grade 5 adverse events (18% vs. 8%).
IGF-1R targeting may merit further evaluation in this disease in selected populations, but combination with docetaxel is not recommended.
© 2014 AACR.