Background Small cell lung cancer (SCLC) is an aggressive tumour type accounting for 10-15 % of lung cancers. The role of thoracic radiotherapy (TRT) in extensive stage SCLC (ESSCLC) in the era of checkpoint inhibitors (CPIs) is undefined. Methods SAKK 15-19 is a national, multicenter, single-arm prospective phase II study evaluating consolidative TRT after standard first-line chemotherapy plus durvalumab in ES-SCLC. Patients (pts) with confirmed ES-SCLC and ECOG ≤ 1 received carboplatin AUC5 (day 1), etoposide 100 mg/m² (days 1-3) and durvalumab 1500 mg (day 1) for 4 cycles, followed by maintenance durvalumab every 4 weeks for up to 2 years in pts without progression. TRT (39 Gy in 13 fractions over 2. 5 weeks) was delivered within 5 weeks after chemoimmunotherapy. Prophylactic cranial irradiation was permitted. The primary endpoint was 12-month progression-free rate (PFR) ; secondary endpoints included progression-free survival (PFS), response rate and overall survival (OS). The study aimed at a 12-month PFR ≥ 25 % (H1) vs. ≤ 12. 5 %. Results Forty-six pts were enrolled; 37 % had ECOG 0, 30 % had asymptomatic brain metastases. At 29-month follow-up, the 12-month PFR was 15. 6 (95 % CI 7-27. 5), median PFS 6. 4 months (95 % CI 4. 8-7. 2) and median OS 15. 0 months (95 % CI 10. 2-22. 0). Grade 3-4 treatment-related adverse events (TRAEs) occurred in 23. 9 % of pts, mainly neutropenia (23. 9 %) and thrombocytopenia (8. 4 %). One pt (2 %) had grade 5 sepsis; no severe TRT-related toxicities were observed. Conclusions Adding consolidative TRT after chemotherapy plus durvalumab in ES-SCLC didn't meet the primary endpoint of the expected 12-month PFR. No additional severe toxicities from TRT were observed. Ongoing larger Phase III trials, including RAPTOR (LNRG LU007), will further define TRT's role in this setting.
Addeo et al. (2026) studied this question.