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First-Line Treatment With Osimertinib in EGFR Mutation–Positive Advanced NSCLC

By: Bruce Cleary
Posted: Tuesday, October 31, 2017

Reporting in the Journal of Clinical Oncology, Suresh S. Ramalingam, MD, of Emory University School of Medicine in Atlanta, and colleagues found that osimertinib demonstrated a “robust” objective response rate and prolonged progression-free survival in treatment-naive patients with epidermal growth factor receptor (EGFR) mutation–positive non–small cell lung cancer (NSCLC). The authors wrote, “There was no evidence of acquired EGFR T790M mutation in postprogression plasma samples.”

Earlier this year, the EGFR tyrosine kinase inhibitor osimertinib was approved by the U.S. Food and Drug Administration for the treatment of patients with EGFR T790M mutation–positive NSCLC whose disease has progressed on or after EGFR tyrosine kinase inhibitor therapy. 

A total of 60 patients with untreated locally advanced or metastatic EGFR-mutant lung cancer received 80 or 160 mg of osimertinib daily. Plasma samples were collected for study when patients had experienced progression of disease to study osimertinib resistance mechanisms.

At a median follow-up of 19.1 months, the overall objective response rate (ORR) in the 80-mg group was 67%, compared with 87% in the 160-mg group. Overall ORR was 77% across doses. Median progression-free survival was longer in the 80-mg group (22. 1 months vs. 19.3 months for the 160-mg group).

In the 50% of patients who had postprogression plasma samples, no circulating tumor DNA could be detected; 9 of 19 patients had putative resistance mechanisms. Acquired EGFR T790M was not detected.