Second-line therapy improves overall survival in primary refractory non-small cell lung cancer (NSCLC) patients

Background: The effect of palliative chemotherapy for non-small cell lung cancer (NSCLC) is well established. Recently, immune checkpoint inhibitors have shown promising efficacy in NSCLC patients. However, little is known about the efficacy of cytotoxic chemotherapy in patients whose tumors are refractory to first-line chemotherapy. We investigated the outcome of all consecutive and unselected patients receiving palliative chemotherapy in a single institution to assess the efficacy of second-line chemotherapy in primary refractory NSCLC. Patients and methods: Patients with metastatic NSCLC diagnosed between 1990 and 2016 were assessed. Outcome parameters were collected and patients were characterized as either having primary progressive disease or clinical benefit [CB; defined as complete/partial remission (CR, PR) or stable disease (SD)]. Probabilities of survival were calculated using the Kaplan-Meier estimator. The log-rank test was used for comparing groups. Cox models were used to explore the prognostic value of covariables. Results: The analysis included 576 patients. Median overall survival (OS) was 9.5 months [95% confidence interval (a) 8.47-10.47]; 62.7% of patients were treated with a platinum-based first-line therapy. Two hundred twenty-two patients (38.5%) were primary refractory to first-line therapy. Median OS was significantly shorter for those patients [7.4 versus 11.5 months, hazard ratio (HR) 1.61 (95% CI 1.34-1.93), P < 0.0001]. Poorer initial performance status was significantly associated with primary refractory disease (P = 0.015). Eighty-one (36.5%) primary refractory patients received a second-line therapy. Median OS was significantly longer for refractory patients receiving second-line therapy versus best supportive care [10.1 versus 5.0 months, HR 0.53 (95% a 0.40-0.72), P < 0.0001]. Conclusions: Nearly 40% of patients are primary refractory to palliative first-line therapy and have a poor prognosis. Active second-line therapy can significantly improve the outcome. Therefore, patients with primary refractory NSCLC should be offered further active therapy. These real-life data for primary refractory patients form the basis for further research in sequencing of current palliative treatment options.