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Soo Park, MD
Soo Park, MD
Posted: Tuesday, November 19, 2024
According to Paul Nghiem, MD, PhD, of the University of Washington, Seattle, and colleagues, more than 50% of patients with Merkel cell carcinoma do not achieve a durable benefit with immunotherapy, despite improved survival outcomes attributed to PD-L1 therapy. These investigators aimed to determine whether adding radiation therapy to immunotherapy could improve progression-free survival among patients with PD-1–refractory advanced Merkel cell carcinoma. Their results were presented during the 2024 Society for Immunotherapy of Cancer (SITC) Annual Meeting (Abstract 783).
“The cohort size was large compared to other reported studies of this nature,” mentioned the study authors. “These results suggest that radiotherapy may be an appropriate salvage modality in immunotherapy-refractory advanced Merkel cell carcinoma patients.”
A total of 41 patients with nodal or distant disease—28 whose disease progressed on immunotherapy and subsequently underwent radiation therapy and 13 who switched to another immunotherapy regimen or changed treatment altogether—were enrolled in this trial. Approximately 71% and 69% of patients in the radiotherapy cohort and the comparison cohort, respectively, were receiving first-line immunotherapy upon disease progression.
The median time on immunotherapy to disease progression was similar between treatment arms (90 vs 92 days). Treatment was received at a median of 30 days after disease progression in the radiotherapy cohort, whereas the comparison cohort received immunotherapy a median of 26 days after disease progression. In the radiotherapy arm, most patients received a single fraction of 8 Gy (n = 15), followed by conventional radiation of 30 to 60 Gy (n = 10), and 18 to 24 Gy in two to three fractions (n = 3).
The median time to last follow-up from treatment initiation was numerically longer among patients who received radiotherapy compared with the comparison arm (15 vs 14 months). Of note, there was a significant improvement in 1-year progression-free survival in the radiotherapy cohort compared with the comparison cohort, with nine and two patients free of disease progression, respectively (32% vs 15%).
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