Real‐world outcomes of NSCLC patients receiving tissue or circulating tumor DNA‐guided osimertinib treatment

BACKGROUND: Osimertinib yields significant tumor responses and durations of progression‐free survival (PFS) in patients with acquired T790M mutations. However, the evidence supporting liquid biopsy‐guided treatment is still limited. This study examined the real‐world benefits of osimertinib in patients with tissue or plasma T790M mutations. METHODS: From January 2016 to June 2018, a total of 183 non‐small‐cell lung cancer patients were enrolled. The presence of the T790M mutation was assessed by either tissue or plasma. The PFS, overall survival, and tumor response rates of the patients were calculated and compared with those of previous clinical trials. RESULTS: T790M mutations were detected in 51.5% of the patients, including 64 of 140 (45.7%) who underwent liquid biopsies and 23 of 29 (79.3%) who underwent tumor biopsies. After excluding those in clinical trials, 46 patients received osimertinib, including 33 with positive plasma and 13 with positive tissue results for T790M mutations. The median PFS was 11.3 months (interquartile range: 5.2‐NR) in all the T790M‐positive patients and 10.1 months (interquartile range: 5.9‐NR) in the plasma T790M‐positive patients. The overall survival, meanwhile, was not reached, whereas the one‐year survival rate was 66.1% in all the patients and 61.4% in those who were plasma T790M‐positive. The objective response rate and disease control rate were 37.8% and 91.9% in all the patients and 34.6% and 92.3% in the plasma T790M‐positive group, respectively. Using a Cox proportional hazards regression, we determined that male gender was a poor prognostic factor for PFS. CONCLUSIONS: In this retrospective real‐world analysis, it was determined that both tissue and plasma T790M mutations can be used to guide treatment with osimertinib. Similar disease control rates and survival durations were observed in comparison to those of phase 3 clinical trials.