Do Chemoimmunotherapy Clinical Trial Results Apply to Real World Patients with Extensive-Stage Small-Cell Lung Cancer?

Chemoimmunotherapy is the standard first-line therapy for patients with extensive-stage small-cell lung cancer (ES-SCLC). The PD-L1 antibodies atezolizumab and durvalumab have been shown to improve survival when combined with a platinum agent and etoposide during induction and continued as maintenance (NEJM JW Oncol Hematol Oct 12 2018 and N Engl J Med 2018; 379:2220 and NEJM JW Oncol Hematol Oct 29 2019 and Lancet 2019; 394:1929). Given that many patients with SCLC do not meet eligibility criteria for participation in clinical trials, there is considerable interest in using data from clinical practice to evaluate outcomes of patients who are underrepresented in clinical trials.

These investigators performed a prospective cohort study of consecutive patients with ES-SCLC who received carboplatin and etoposide with atezolizumab as first-line therapy at 32 hospitals in Japan from 2019 to 2020. Of 207 patients evaluated, median age was 72 years, 31% were aged >75 years, and 89% had performance status 0–1. Overall, 132 patients (64%) were adjudicated to meet eligibility criteria for phase 3 clinical trials and the rest were deemed ineligible based on poor performance status, symptomatic or untreated central nervous system metastases, comorbidities, and abnormal laboratory values.

There was a significant difference in disease control rates between trial-eligible and trial-ineligible patients (93% vs.77%; P=0.002). Median progression-free survival was significantly longer in eligible versus ineligible patients (5.1 vs. 4.7 months; hazard ratio, 0.72; P=0.03; 95% CI, 0.53–0.97) whereas overall survival was numerically but not significantly longer (15.8 vs. 13.1 months, respectively; HR, 0.74; P=0.10; 95%; 95% CI, 0.51–1.07). The rate of severe adverse events was higher in ineligible patients versus eligible patients (39% vs. 27%; P=0.07).