Association Between Smoking History and Overall Survival in Patients Receiving Pembrolizumab for First-Line Treatment of Advanced Non-Small Cell Lung Cancer.

Importance: There is a need to tailor treatments to patients who are most likely to derive the greatest benefit from them to improve patient outcomes and enhance cost-effectiveness of cancer therapies. Objective: To compare overall survival (OS) between patients with a current or former history of smoking with patients who never smoked and initiated pembrolizumab monotherapy as first-line (1L) treatment for advanced non-small lung cancer (NSCLC). Design, Setting, and Participants: This retrospective cohort study compared patients diagnosed with advanced NSCLC aged 18 or higher selected from a nationwide real-world database originating from more than 280 US cancer clinics. The study inclusion period was from January 1, 2011, to October 1, 2019. Exposures: Smoking status at the time of NSCLC diagnosis. Main Outcomes and Measures: OS measured from initiation of 1L pembrolizumab monotherapy. Results: In this retrospective cohort study, a total of 1166 patients (median [IQR] age, 72.9 [15.3] years; 581 [49.8%] men and 585 [50.2%] women) were assessed in the primary analysis, including 91 patients [7.8%] with no history of smoking (ie, never-smokers) and 1075 patients [92.2%] who currently or formerly smoked (ie, ever-smokers). Compared with ever-smokers, never-smokers were older (median age [IQR] of 78.2 [12.0] vs 72.7 [15.5] years), more likely to be female (61 [67.0%] vs 524 [48.7%]) and to have been diagnosed with nonsquamous tumor histology (70 [76.9%] vs 738 [68.7%]). After adjustment for baseline covariates, ever-smokers who initiated 1L pembrolizumab had significantly prolonged OS compared to never-smokers (median OS: 12.8 [10.9-14.6] vs 6.5 [3.3-13.8] months; hazard ratio (HR): 0.69 [95% CI, 0.50-0.95]). This trend was observed across all sensitivity analyses for the 1L pembrolizumab cohort, but not for initiators of 1L platinum chemotherapy, for which ever-smokers showed significantly shorter OS compared with never-smokers (HR, 1.2 [95% CI, 1.07-1.33]). Conclusions and Relevance: In patients with advanced NSCLC who received 1L pembrolizumab monotherapy in routine clinical practices in the US, patients who reported a current or former history of smoking at the time of diagnosis had consistently longer OS than never-smokers. This finding suggests that in never-smoking advanced NSCLC, 1L pembrolizumab monotherapy may not be the optimal therapy selection, and genomic testing for potential genomically matched therapies should be prioritized over pembrolizumab in never-smokers.