ATLANTA – A combination of the epidermal growth factor receptor (EGFR)–targeted agent osimertinib (Tagrisso) with savolitinib, an investigational MET inhibitor, showed activity against MET-driven non–small cell lung cancer (NSCLC) in patients for whom prior lines of EGFR-targeted therapy had failed.
Neil Osterweil/MDedge News
Dr. Lecia V. Sequist
Results of the phase 1b TATTON trial suggest that it may be possible to overcome MET-driven drug resistance to tyrosine kinase inhibitors (TKIs) by targeting MET amplification, said Lecia V. Sequist, MD, from the Massachusetts General Hospital Cancer Center in Boston.
“We’ve seen that up to 10% of patients at the time of acquired resistance progressing on first- or second-generation EGFR TKIs and up to 25% of patients progressing on third-generation TKIs will have resistance driven by MET amplification,” she said at a briefing at the annual meeting of the American Association for Cancer Research.
Preliminary analysis of next-generation sequencing of circulating tumor DNA showed that MET amplification was the most common resistance mechanism, occurring in 15% of patients treated for NSCLC with first-line osimertinib in the FLAURA trial. In the AURA3 trial, MET amplification was the mechanism of resistance to second-line osimertinib in 19% of patients, she said.
Savolitinib is a selective oral MET-targeted TKI that has shown preliminary antitumor activity in patients with resistance to EGFR TKIs caused by MET amplification.
Dr. Sequist presented updated interim data on two cohorts of patients enrolled in the phase 1b trial evaluating osimertinib and savolitinib in patients with advanced or metastatic NSCLC bearing EGFR mutations following failure of one or more prior EGFR-targeted TKIs. A separate cohort of patients was treated with osimertinib and selumetinib, an investigational inhibitor of MEK1/2.
In the dose-expansion phase of the trial, enrolled patients with EGFR mutation–positive and MET-positive NSCLC, and divided them into two groups: patients who received prior therapy with a first- and/or second-generation EGFR-targeted TKI who were negative for the T790M resistance mutation and patients who had received prior treatment with a third-generation EGFR TKI, regardless of mutational status.
Of 46 patients treated with first- and/or second-generation agents, 24 had partial responses for an overall response rate of 52%. Of the remaining 22 patients, 16 (35%) had stable disease for at least 6 weeks, 3 had disease progression, and 3 were not evaluable. The median time to response was 43 days.
The most common adverse events of grade 3 or greater in this cohort were nausea (4%), fatigue (7%), vomiting (4%), peripheral edema (2%), decreased white blood cell count (2%), pain (7%), AST increase (8%), rash (4%), and decreased neutrophil count (8%).
Among 48 patients treated with the combination after disease progression on a third-generation EGFR TKI, 12 had a partial response, for an overall response rate of 25%. In addition, 21 of the 36 patients without objective responses had stable disease for at least 6 weeks, 6 had disease progression, and 9 were not evaluable. The median time to response was 46 days.
In this cohort, the most common adverse events, independent of causality, included nausea (2%), vomiting (4%), diarrhea (2%), fatigue (4%), decreased appetite (6%), and myalgia (1%). “Our data suggest that the combination of osimertinib and savolitinib could overcome MET-driven resistance, but certainly further research is needed to determine the final effectiveness of these therapies,” Dr. Sequist said.
The combination is being explored in two studies: the ongoing single-arm, phase 2 SAVANNAH trial in patients with advanced EGFR-mutant, MET-positive NSCLC who had disease progression on a prior course of osimertinib; and ORCHARD, currently in the planning stages as a phase 2 trial in patients with advanced NSCLC who had disease progression on first-line osimertinib.
The ORCHARD trial will have multiple biomarker-matched and nonmatched treatment arms to examine both targeted and nontargeted combinations.
“I would say this is impressive early data,” said Roy S. Herbst, MD, PhD, chief of medical oncology at Yale Cancer Center and Smilow Cancer Hospital in New Haven, Conn., the invited discussant in the session where Dr. Sequist presented the data.
“We need randomized trials to confirm the results, need to better define MET-selection criteria, and this could in the future be a very useful refractory EGFR therapy,” he said.
The TATTON trial is sponsored by AstraZeneca. Dr. Sequist reported serving as an advisory board member and receiving research support and honoraria from the company. Dr. Herbst reported receiving research support from AstraZeneca, Eli Lilly, and Merck, and has served as a consultant for AstraZeneca, Eli Lilly, Genentech/Roche, Merck, NextCure, and Pfizer.
SOURCES: Yu H et al. AACR 2019, Abstract CT032; Sequist LV et al. AACR 2019, Abstract CT033.