Synergy between VEGF/VEGFR inhibitors and chemotherapy agents in the phase I clinic

Abstract

Purpose: We hypothesized that chemotherapy synergizes with VEGF/VEGFR (VEGF/R) inhibitors in patients with advanced solid malignancies. Experimental Design: Patients treated on phase I protocols between December 2004 and July 2013 (n = 1,498) were included in this analysis. The primary outcome was clinical benefit, defined as stable disease ≥6 months, complete response, or partial response. Two odds ratios (OR) for achieving clinical benefit were calculated: one for patients treated with VEGF/R inhibitors (OR with VEGF/R) and another for patients treated without (OR without VEGF/R). To compare these two ORs, an interaction term was included in the multivariate model: (chemotherapy/factor of interest)×(VEGF/R). We took significant interaction terms (Pinteraction < 0.05) to suggest effect modification (either synergy or antagonism) with VEGF/R inhibitors. Results: All patients treated with VEGF/R inhibitors exhibited higher OR for clinical benefit than those who were not [OR = 1.9; 95% confidence interval (CI), 1.5-2.4; P < 0.0001]. Use of chemotherapy agents concomitant with VEGF/R inhibitors was associated with significantly higher OR for clinical benefit compared with chemotherapy use without VEGF/R inhibitors [OR with VEGF/R = 1.6 (95% CI, 1.1-2.5) vs. OR without VEGF/R = 0.4 (95% CI, 0.3-0.6), Pinteraction = 0.02]. Specifically, the antimetabolite class was associated with the greatest increase in OR for clinical benefit [OR with VEGF/R = 2.7 (95% CI, 1.5-4.7) vs. OR without VEGF/R = 0.2 (95% CI 0.1-0.3), Pinteraction = 0.004]. Conclusions: VEGF/R inhibitor was found to synergize with chemotherapeutics. This effect was most pronounced with the antimetabolite class.