Irradiating a small number of metastatic lesions does not appear to improve progression-free or overall survival in patients receiving immune checkpoint inhibitor monotherapy for advanced cancer.
In the phase 2 CHEERS trial, 52 patients with advanced solid tumors were randomized to anti-PD-1/PD-L1 monotherapy and 47 patients to the same treatment plus stereotactic body radiotherapy (3 x 8 Gy) to a maximum of three lesions prior to the second or third cycle of an immune checkpoint inhibitor.
Patients had locally advanced or metastatic melanoma, renal cell carcinoma, urothelial carcinoma, non-small cell lung carcinoma, or head and neck squamous cell carcinoma and were treated at five Belgian hospitals.
Most patients had more than three lesions.
Seven patients in the experimental group did not complete radiotherapy due to early progression or intercurrent illness.
Over a median follow-up of 12.5 months, median progression-free survival was 4.4 months in the radiotherapy group versus 2.8 months in the control group (hazard ratio [HR], 0.95; P = .82).
Median overall survival was not significantly better with radiotherapy compared with the control group (14.3 vs 11 months; HR, 0.82; P = .47), nor was the objective response rate (27% vs 22%; P = .56).
However, a post hoc analysis demonstrated a significant association between the number of irradiated lesions and overall survival among patients receiving radiotherapy (HR, 0.31; P = .002).
The incidence of grade 3 or worse treatment-related adverse events was 18% in both groups.
Although the study was negative overall, the post hoc analysis coupled with "recent evidence suggests that treating all active disease sites with higher radiation doses...may be a more promising strategy to optimize systemic disease control," the authors concluded.
The study was led by Mathieu Spaas, MD, Department of Radiation Oncology, Ghent University, Belgium, and published online July 6 in JAMA Oncology.
There was insufficient power to detect if certain cancers benefited more from add-on radiation because of the small sample size.
More than half of patients in the control group had already received some form of radiotherapy before study inclusion, which may mean the study underestimated the benefit of radiotherapy.
The work was funded by Kom Op Tegen Kanker and Varian Medical Systems.
Investigators disclosed numerous industry ties, including Merck, Novartis, and Bristol Myers Squibb.
M. Alexander Otto is a physician assistant with a master ' s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape and is also an MIT Knight Science Journalism fellow. Email: firstname.lastname@example.org
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Cite this: No Benefit to Adding Limited Radiation in Advanced Cancer - Medscape - Jul 10, 2023.