Masitinib in nonresectable pancreatic cancer: Results of a phase III randomized placebo-controlled trial.

Abstract

158 Background: Masitinib is a selective c-Kit inhibitor that efficiently inhibits mast cell function. Increased mast cell activity in the tumor microenvironment has been linked to poor prognosis in pancreatic cancer (PC) patients. Methods: In a randomized (1:1 ratio), double-blind, international phase III trial, chemo-naïve PC patients (n=348) received either masitinib (9 mg/kg/day) in combination with gemcitabine (1000 mg/m2/wk) (M+G) or placebo plus gemcitabine (P+G). Primary endpoint was overall survival (OS). An ancillary pharmacogenomic study, based on RNA extracted from whole blood prior to treatment, was conducted in a subset of patients. Results: In the overall population median OS was not significantly improved in the M+G arm as compared with the P+G arm (median OS: 7.7 vs. 7.0 months, respectively; p=0.74, HR=0.90 [0.71; 1.14]). However, M+G treatment led to a significant survival advantage in two subpopulations. First, in patients with ‘pain’ at baseline (defined as a VAS score >20 mm on a 100 mm scale) (44% of patients with pain intensity data available) median OS was significantly increased from 5.4 months in the P+G arm to 8.1 months in the M+G arm (p=0.010; HR:0.61 [0.42; 0.88]); OS rates at 12 and 18 months were respectively, 32.2% and 18.2% in the M+G arm vs. 17.8% and 7.8% in the P+G arm. Second, in patients with a specific deleterious genomic biomarker (GBM) consisting of a limited number of genes (66% of patients with genetic data available), median OS was significantly increased in the M+G arm as compared with the P+G arm (11.0 vs. 5.0 months, respectively) (p=0.000038; HR=0.29 [0.17; 0.51]); OS rates at 12 and 18 months were respectively, 41.4% and 18.5% in the M+G arm vs. 11.1% and 4.2% in the P+G arm. In patients without pain (defined as VAS <5 mm and no need for opioid analgesics), median OS was 15.4 months in the P+G arm. In patients without the deleterious GBM, median OS in the P+G arm was 14.3 months. In these two patient populations M+G treatment was contraindicated. The general safety profile of the M+G combination regimen was acceptable. Conclusions: Masitinib in combination with gemcitabine provides a significant survival advantage over gemcitabine monotherapy in PC patients with ‘pain’ and patients with a specific GBM. Clinical trial information: NCT00789633.