The addition of the cancer immunotherapy drug atezolizumab to the standard of care concurrent chemoradiation (cCRT) did not improve overall survival for patients with limited-stage small cell lung cancer (LS-SCLC) in the second planned interim analysis of the NRG Oncology/Alliance NRG-LU005 clinical trial.

These results were recently reported during the Plenary Session of the American Society for Radiation Oncology Annual Meeting in Washington, DC.

“While atezolizumab given concurrently with chemoradiation did not improve survival, we have still learned quite a bit from these findings. With the success of the ADRIATIC trial presented at ASCO earlier this year, it is clear that LS-SCLC patients benefit from immunotherapy, but it should be given after completion of chemoradiation and not concurrently. Our results also suggest that twice daily radiation may have performed better and could be considered the preferred radiation regimen for these patients,” stated Kristin A. Higgins, MD, Professor of Radiation Oncology at City of Hope National Medical Centre and Chief Clinical Officer, City of Hope Atlanta, and the lead author of the NRG-LU005 abstract.

NRG-LU005 is an open-label, randomised, phase III, international clinical study that enrolled 554 eligible patients with LS-SCLC in the U.S. and Japan.

Patients received one cycle of chemotherapy prior to registration onto the trial.

Following registration, patients were stratified by choice of cisplatin or carboplatin chemotherapy, their radiation fractionation schedule, sex, and ECOG performance status and then were randomly assigned to receive either cCRT alone or cCRT with atezolizumab at 1200 mg every three weeks for a maximum of 17 cycles.

The primary aim of NRG-LU005 was to compare overall survival with and without atezolizumab.

At the second planned interim analysis at a median follow up of 21 months for all patients, the 1, 2, and 3 year overall survival rates were  82.6% (95% CI 77.2 - 86.9), 62.9% (95% CI 56.2 - 69.0) and 50.3% (95% CI 42.3 - 57.8) for control, and 80.2% (95% CI 74.7 - 84.6), 58.6% (95% CI 52.1- 64.6) and 44.7% (95% CI 36.6 - 52.4) for adding atezolizumab, respectively.

The median overall survival for cCRT alone was 39.5 months (95% CI 27.5 - Not reached) and 33.1 months for the atezolizumab arm (HR= 1.11, 95% CI: 0.85-1.45). 

No new or unexpected safety findings were noted.

In addition to the primary objectives, NRG-LU005 also included secondary objectives comparing the following rates between treatments: progression-free survival, distant metastasis-free survival, cumulative incidence of local failure, complete or partial response, and adverse events.

This study was sponsored by the National Cancer Institute (NCI), part of the National Institutes of Health,  was supported by grants U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG Oncology SDMC), UG1CA189867 (NCORP), U24CA196067 (NRG Specimen Bank), U24CA180803 (IROC) from the NCI and Genentech by Genentech, a member of the Roche Group under a Cooperative Research and Development Agreement between NCI and Genentech.

Source: NRG Oncology