Treatments and outcomes of advanced/recurrent non-small cell lung cancer harboring the EGFR T790M mutation: A retrospective observational study of 141 patients in Japan

Background: The epidermal growth factor receptor (EGFR) T790M mutation is considered the major mechanism of acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) in nonsmall cell lung cancer (NSCLC) patients with EGFR-sensitizing mutations. Although chemotherapy is commonly used for those patients under the condition without T790M-targeted therapy, the clinical outcomes are poorly defined. Therefore, we aimed to reveal the treatment patterns and clinical outcomes in patients with T790M-positive NSCLC. Methods: We conducted a retrospective observational study at 23 sites in Japan, and 141 patients with T790M-positive advanced/recurrent NSCLC were identified from January 2008 to December 2014. Their records were studied to understand treatment patterns after detection of a T790M mutation and to assess the objective response rate (ORR) and median survival time (MST) to specific treatment modalities. Results: Of 141 patients, 24 had de novo T790M-positive tumors and 117 had acquired T790Mpositive tumors, with MSTs (95% CI) of 21.4 (12.4-36.7) and 9.1 (6.4-13.9) months, respectively. The most common regimen was platinum-based doublet chemotherapy ± bevacizumab, which was associated with an ORR/MST of 25.0%/29.1 months, respectively, in patients with de novo T790M mutations, and 22.2%/15.3 months, respectively, in patients with acquired T790M mutations. Conclusions: This study reveals the treatment patterns and outcomes of NSCLC patients in Japan after detection of the T790M mutation. The most common treatment following detection of the T790M mutation was platinum-based doublet chemotherapy ± bevacizumab. Platinum-based doublet chemotherapy ± bevacizumab was moderately effective, indicating the need for targeted therapies for patients with T790M mutation-positive NSCLC.