Adding Atezolizumab to Chemoradiation Fails to Improve Outcomes for Limited-Stage SCLC
Key Clinical Takeaways:
- Key Outcomes: Adding concurrent and adjuvant atezolizumab to chemoradiation (CRT) did not improve outcomes in LS-SCLC, with no significant differences in OS (36.1 vs 31.1 months; HR 1.03), PFS, or distant metastasis–free survival compared with chemoradiation alone.
- Design/Population: NRG Oncology/Alliance LU005 was an international, open-label, phase 3 trial enrolling patients with limited-stage SCLC who received induction platinum-etoposide followed by randomization to standard CRT with or without concurrent and adjuvant atezolizumab.
- Clinical Relevance: These results indicate that immune checkpoint inhibition with atezolizumab does not add benefit to definitive chemoradiation in LS-SCLC, supporting continued use of CRT alone as standard of care in this setting.
The addition of concurrent and adjuvant atezolizumab to standard chemoradiation did not improve survival outcomes for patients with limited-stage small cell lung cancer (LS-SCLC), according to results from the phase 3 NRG Oncology/Alliance LU005 trial.
This trial evaluated whether the addition of atezolizumab to standard concurrent chemoradiation (CRT) could improve outcomes among patients with LS-SCLC. While immune checkpoint inhibition has demonstrated survival benefit for extensive-stage disease, its role in the curative-intent setting for LS-SCLC remains uncertain.
In this open-label, international study, patients with LS-SCLC and ECOG performance status 0 to 2 received one induction cycle of platinum-etoposide chemotherapy prior to randomization. Participants were then assigned to receive either standard CRT alone or CRT combined with concurrent and adjuvant atezolizumab administered at 1,200 mg every three weeks for up to 17 cycles or until disease progression or unacceptable toxicity.
Randomization was stratified by platinum agent (cisplatin vs carboplatin), radiation fractionation schedule (66 Gy once daily vs 45 Gy twice daily), sex, and performance status. The primary end point was overall survival (OS), with secondary end points including progression-free survival (PFS), objective response rate, local control, and distant metastasis–free survival (DMFS).
Between May 2019 and December 2023, patients were enrolled and followed for efficacy outcomes. Median OS was 36.1 months in the CRT-alone arm compared with 31.1 months in the CRT plus atezolizumab arm (Hazard ratio [HR] 1.03; 95% confidence interval [CI], 0.80 to 1.32). Median PFS was similar between groups at 11.4 months with CRT alone and 12.1 months with the addition of atezolizumab (HR 0.98; 95% CI, 0.79 to 1.22). Median DMFS was also comparable, at 13.0 months versus 16.8 months, respectively (HR 0.96; 95% CI, 0.76 to 1.21). No unexpected safety signals were observed with the incorporation of concurrent atezolizumab.
In conclusion, the addition of concurrent and adjuvant atezolizumab to standard chemoradiation did not improve survival outcomes among patients with limited-stage SCLC. These results indicate that, unlike in extensive-stage disease, immune checkpoint inhibition does not currently confer added benefit in the definitive CRT setting for LS-SCLC.
Source:
Higgins K, Hu C, Ross H J, et al. Chemoradiation ± atezolizumab in limited-stage small cell lung cancer: results of NRG Oncology/Alliance LU005. J Clin Oncol. Published online January 13, 2026. https://ascopubs.org/doi/10.1200/JCO-25-01569
