Chemoradiation ± Atezolizumab in Limited-Stage Small Cell Lung Cancer: Results of NRG Oncology/Alliance LU005.

PURPOSE: NRG Oncology/Alliance LU005 (ClinicalTrials.gov identifier: NCT03811002) tested the addition of atezolizumab to concurrent chemoradiation (CRT) in this open-label, phase III international trial. METHODS: Patients with limited-stage small cell lung cancer (LS-SCLC), stage Tx-IV, N0-3, and M0 with Eastern Cooperative Group performance status (PS) 0-2 received one cycle of chemotherapy (platinum/etoposide) before study registration and were randomly assigned to CRT alone versus CRT plus concurrent and adjuvant atezolizumab, 1,200 mg once daily, every 3 weeks until investigator-assessed progression or intolerable side effects for a maximum of 17 cycles. Patients were stratified by choice of chemotherapy (cisplatin v carboplatin), radiation fractionation schedule (66 Gy once daily v 45 Gy twice daily), sex, and PS (0/1 v 2). The primary end point was overall survival (OS). Secondary end points included investigator-assessed progression-free survival (PFS), objective response rate, local control, and distant-metastasis-free survival (DMFS). RESULTS: patients were randomly assigned from May 2019 to December 2023. The median OS was 36.1 months (95% CI, 28.1 to 42.5) for the CRT-alone arm and 31.1 months (95% CI, 28.5 to 44.7) for the CRT + atezolizumab arm, respectively (hazard ratio [HR], 1.03 [95% CI, 0.80 to 1.32]). The median PFS was 11.4 months (95% CI, 10.3 to 13.2) for the CRT-alone arm and 12.1 months (95% CI, 10.9 to 15.2) for the CRT + atezolizumab arm, respectively (HR, 0.98 [95% CI, 0.79 to 1.22]). The median DMFS was 13.0 months (95% CI, 11.3 to 18.2) for the CRT-alone arm and 16.8 months (95% CI, 12.1 to 21.6) for the CRT + atezolizumab arm (HR, 0.96 [95% CI, 0.76 to 1.21]). No unexpected safety signals with concurrent atezolizumab were observed. CONCLUSION: Concurrent and adjuvant atezolizumab with chemoradiation did not improve survival in patients with LS-SCLC.