Real-world first-line serplulimab-based immunochemotherapy for extensive-stage small cell lung cancer: The multicenter ASTRUM-005R study.

e20106 Background: In the phase 3 ASTRUM-005 study (NCT04063163), serplulimab, an anti-PD-1 monoclonal antibody, combined with chemotherapy, demonstrated promising antitumor activity as first-line treatment in patients with extensive-stage small cell lung cancer (ES-SCLC). This led to its approval by the NMPA and designation as an orphan drug by the FDA. Here, we present a multicenter cohort study investigating the real-world efficacy and safety of first-line serplulimab-based immunochemotherapy for ES-SCLC in China. Methods: This cohort study enrolled adult patients with ES-SCLC at 12 sites in China from April 2022 to December 2023. These patients received at least two cycles of first-line serplulimab combined with an etoposide-platinum regimen and underwent at least one response assessment. The primary endpoint was real-world progression-free survival (rwPFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), and safety profiles. Results: A total of 420 patients were enrolled and evaluated for both efficacy and safety. The participants had a median age of 63 years (range 30-84), with 361 (85.95%) being male and 310 (73.81%) having a history of smoking. Most patients (386, 91.91%) had an ECOG PS of 0 or 1. Comorbidities, excluding other primary tumors, were present in 40.95% (172 patients). Liver and brain metastases were observed in 32.14% (n = 135) and 21.67% (n = 91), respectively. The median number of immunochemotherapy cycles was 4 (range 2-6), with 45.24% (n = 190) receiving more than 4 cycles. The median rwPFS was 9.1 months (95% CI 8.2-9.7), with a 1-year rwPFS rate of 34.3%, surpassing the 1-year PFS rate of 28.2% reported for the Asian in the ASTRUM-005 study. The median rwPFS was 9.8 months (95% CI 9.1-12.8) in patients without liver metastasis, significantly longer than the 6.7 months (95% CI 6.1-8.7) in patients with liver metastasis ( P < 0.0001). Patients who received radiotherapy also had a significantly longer median rwPFS of 9.8 months (95% CI 8.6-15.1) compared to 8.7 months (95% CI 7.3-9.6) for patients who did not receive radiotherapy ( P = 0.022). Additionally, patients who received > 4 cycles of immunochemotherapy had a median rwPFS of 10.5 months (95% CI 9.3-13.3), which was significantly longer than the 6.6 months (95% CI 5.6-9.1) in patients who received ≤4 cycles ( P < 0.0001). The ORR was 69.71%, and OS was not yet mature. Safety analysis revealed grade ≥3 AEs occurring in 19.05% of the cases. Conclusions: This cohort study reports the real-world survival outcomes of first-line serplulimab-based immunochemotherapy and provides valuable insights in a clinical setting. The study complements the ASTRUM-005 study, offering further evidence in ES-SCLC.