Osimertinib 80 mg EOD? Does this work?

Osimertinib is a third-generation thyroxine kinase inhibitor (TKI) used in treating advanced non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation. Osimertinib is used as a second line treatment for patients who develop EGFR T790 M resistance mutation rather than first line due to financial constraints. We present a case of a 60-year-old Chinese gentleman who diagnosed as stage 4 adenocarcinoma with EGFR Exon 19 deletion. His disease progressed after a year of treatment with afatinib. His plasma T790 M was negative and due to delay in tissue biopsy, he was empirically started on osimertinib. However, in view of financial concerns, he opted a dose reduction of 80 mg every alternate day rather than the conventional dose of 80 mg daily. Serial CT Thorax showed partial response based on RECIST 1.1 criteria and he has 9 months of progression free survival. This case report shows that Osimertinib in reduced dose may achieve good partial response and progression free survival in patients.