Osimertinib is the best treatment choice for patients with epidermal growth factor receptor (EGFR)-mutated advanced non-small-cell lung cancer (NSCLC) whose disease progresses on a first- or second-generation EGFR-tyrosine kinase inhibitor due to acquired T790M mutation. On the other hand, there is a lack of therapeutic strategies with proven efficacy at the time of progression on osimertinib. If not administered previously, platinum-based chemotherapy can provide some clinical benefit, while immunotherapy does not seem to work in this setting. Here, we report on a unique case of response to osimertinib rechallenge after intervening chemotherapy in an EGFR T790M-positive NSCLC patient pretreated with the sequence erlotinib-osimertinib.