EML4-ALK Rearrangement as a Mechanism of Resistance to Osimertinib in Metastatic Lung Adenocarcinoma: A Case Report

Osimertinib, a third-generation EGFR tyrosine kinase inhibitor, is the preferred frontline therapy for EGFR-mutant advanced NSCLC. However, despite its high initial response rates, multiple EGFR-independent mechanisms of resistance have been reported in patients receiving osimertinib. One such mechanism is the emergence of acquired, targetable oncogenic fusion events. It has been documented in other case reports that combination therapies can be efficacious in these scenarios. In our case report, we present a patient with EGFR-mutant advanced NSCLC who developed an acquired EML4-ALK rearrangement mediating resistance to osimertinib, which was overcome by using a combination of osimertinib with the ALK tyrosine kinase inhibitor alectinib.