SAN FRANCISCO—The addition of onartuzumab to mFOLFOX6 for the treatment of patients with metastatic gastroesophageal adenocarcinoma (GEC) did not improve progression-free survival in the total population or in MET-positive patients, a study (Abstract 2) presented this week at the 2015 Gastrointestinal Cancers Symposium has shown.

Up-regulation of the MET/HGF pathway is known to be associated with a poor prognosis in patients with various cancers, including GEC. Onartuzumab, a fully humanized, monovalent anti-HET antibody, inhibits HGF binding and receptor activation. Therefore, researchers sought to investigate the safety and efficacy of onartuzumab plus mFOLFOX6 in previously untreated patients with metastatic, HER2-negative GEC in this phase 2 study.

Researchers enrolled 123 patients from 25 sites and randomly assigned them 1:1 to receive mFOLFOX6 plus onartuzumab 10 mg/kg or placebo. In the investigational arm, 33% of patients were MET-positive versus 28% of the placebo arm.

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Results showed that 74% of patients in the onartuzumab arm experienced progression-free events compared with 82% in the placebo arm and median progression-free survivals were 6.77 months and 6.97 months in the onartuzumab and placebo arms, respectively (HR = 1.08; 95% CI: 0.71,1.63). In patients with MET-positive disease, median progression-free survival was 5.95 months for onartuzumab and 6.8 months for placebo (HR = 1.38; 95% CI: 0.60,3.20).

In regard to safety, the most common serious adverse events that were more frequently associated with onartuzumab than placebo were neutropenia, thrombocytopenia, peripheral edema, and pulmonary embolism. Serious adverse events were more commonly observed in the onartuzumab group than the placebo group.


  1. Shah MA, Cho JY, Huat ITB, et al. Randomized phase II study of FOLFOX +/- MET inhibitor, onartuzumab (O), in advanced gastroesophageal adenocarcinoma (GEC). J Clin Oncol. 2015;33:(suppl 3; abstr 2).