ASCO20: Dual EGFR Tyrosine Kinase Inhibitor Therapy for EGFR-Mutated NSCLC
Posted: Wednesday, June 17, 2020
Dual EGFR tyrosine kinase inhibitor therapy with osimertinib and gefitinib was found to be well tolerated as a first-line treatment for EGFR-mutated non–small cell lung cancer (NSCLC), according to phase I/II findings presented during the ASCO20 Virtual Scientific Program (Abstract 9507). Julia K. Rotow, MD, of Dana-Farber Cancer Institute, Boston, and colleagues also found rapid plasma clearance of the EGFR mutation in patients given the combination therapy.
From May 2017 to July 2019, the clinical trial enrolled patients with stage IV EGFR-mutated NSCLC with no history of treatment. The first phase of the study involved finding the maximum tolerated dose. Six patients were administered a daily dose of either 40 or 80 mg of osimertinib with 250 mg of gefitinib. The second phase studied the feasibility of receiving the maximum tolerated dose for at least six 4-week cycles in 21 patients.
The maximum tolerated dose was 80 mg of osimertinib plus 250 mg of gefitinib orally daily. A total of 81.5% of patients who received this dose completed at least six 4-week treatment cycles. The overall best response was an partial response rate of 85.2%, with 14.8% achieving stable disease.
In terms of clearance rates for plasma EGFR mutations, 68% were detected to have the driver EGFR mutation, which was undetectable in 82.4% of these patients after 2 weeks of treatment. Common adverse events for the combination treatment included rash (any grade: 96.3%; grade 3: 3.7%), diarrhea (any grade: 85.2%; grade 3: 11.1%), and dry skin of any grade.
After a 14.8-month follow-up, the median progression-free survival was not reached. However, the authors noted the clinical trial is currently ongoing. “Analysis of survival outcomes and acquired resistance mechanisms are pending data maturity and will facilitate understanding of the role of first-line dual EGFR TKI therapy for this patient population.”
Disclosure: The study authors’ disclosure information can be found at coi.asco.org.
