Real-world efficacy and safety of tarlatamab in previously treated small cell lung cancer in Korea

초록

Background: Despite advances in non-small cell lung cancer, therapeutic progress in small cell lung cancer (SCLC) remains limited. Tarlatamab, a novel bispecific T-cell engager targeting delta-like ligand 3, has shown promise in clinical trials. However, its real-world safety and efficacy, particularly regarding cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), remain underexplored. Methods: We retrospectively analyzed 10 Korean patients with previously treated extensive-stage SCLC who received tarlatamab through an expanded-access program between October 2024 and July 2025. Results: A partial response was observed in five patients (50.0%), stable disease in two (20.0%), and progressive disease in three (30.0%). The median progression-free survival (PFS) was 3.9 ± 0.7 months (95% confidence interval [CI]: 2.5–5.3), and mean PFS was 5.3 ± 1.1 months (95% CI: 3.2–7.4). The mean tumor size reduction was −5.5%. CRS occurred in seven patients (70%), all during the first cycle, and was limited to grades 1–2, with no severe cases or treatment discontinuations. One patient developed grade 3 ICANS. A higher neutrophil-to-lymphocyte ratio (NLR) was associated with CRS (P = 0.007). Hematologic toxicity was mild, with no neutropenia or grade ≥ 3 events. Conclusions: Tarlatamab demonstrated encouraging antitumor activity and a manageable safety profile in heavily pretreated Korean SCLC patients. CRS was common but mild, whereas ICANS was rare. An elevated NLR may predict the risk of CRS. These findings are consistent with previous trial data and support the potential use of tarlatamab as a treatment option for SCLC.