Long-term outcome of chemoimmunotherapy for extensive-stage small-cell lung cancer according to key clinical trial eligibility: 3-year outcomes from a prospective cohort study.

Background: Chemoimmunotherapy is the standard first-line treatment for extensive-stage small-cell lung cancer (ES-SCLC); however, its real-world long-term outcomes associated with patient backgrounds are still unclear. We explored this association using an updated large real-world prospective cohort with a minimum follow-up of 3 years.

Methods: This prospective cohort study, conducted across 32 hospitals, enrolled patients with ES-SCLC receiving carboplatin, etoposide, and atezolizumab between September 1, 2019 and September 30, 2020. Updated data with a minimum 3-year follow-up period were analyzed. Patients who met eligibility criteria for pivotal phase 3 clinical trials were considered "trial-eligible."

Results: The median (range) time from the treatment initiation to data cutoff (September 30, 2023) was 42.2 (35.8-48.2) months for the enrolled 207 patients. Most patients (89 %) had an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients fulfilling the inclusion criteria (132 [64 %]) were categorized as trial-eligible. The 3-year progression-free survival (PFS) probability and overall survival (OS) were 6.1 % and 20.9 %, respectively. The 3-year OS probabilities for trial-eligible and trial-ineligible patients were 26.7 and 9.5 %, respectively. The trial-eligible cohort had a larger percentage of patients achieving a 3-year OS (30/132, 22.7 %) than the trial-ineligible cohort (5/75, 6.7 %) (P = 0.003) CONCLUSIONS: Our study provides the first documentation of the long-term outcomes following chemoimmunotherapy in a large prospective real-world cohort of patients with ES-SCLC. Key eligibility criteria significantly influenced the long-term effectiveness. These findings provide valuable insights into the practical effectiveness of chemoimmunotherapy and clinical decision-making for patients with ES-SCLC.