Extended Follow-Up Outcomes from Pooled Prospective Studies Evaluating Efficacy of Interstitial Alpha Radionuclide Treatment for Skin and Head and Neck Cancers.

Simple Summary: While the initial favorable efficacy and safety profile for a novel diffusing alpha-emitter radiation therapy (Alpha DaRT) have been previously demonstrated, the longer-term safety and durability of the treatment are unknown. In this pooled analysis of 81 treated head and neck or skin tumors from four clinical trials with a median follow-up of 14 months, a complete response was observed in 89% of treated lesions, two-year local recurrence-free survival was 77%, and there were no grade 2 or higher late toxicities observed. These results suggest that Alpha DaRT is a safe and effective treatment for skin and head and neck tumors. The initial favorable efficacy and safety profile for Alpha DaRT have been demonstrated (NCT04377360); however, the longer-term safety and durability of the treatment are unknown. This pooled analysis of four prospective trials evaluated the long-term safety and efficacy of Alpha DaRT for the treatment of head and neck or skin tumors. A total of 81 lesions in 71 patients were treated across six international institutions, with a median follow-up of 14.1 months (range: 2–51 months). Alpha DaRT sources were delivered via a percutaneous interstitial technique and placed to irradiate the tumor volume with the margin. The sources were removed two to three weeks following implantation. A complete response was observed in 89% of treated lesions (n = 72) and a partial response in 10% (n = 8). The two-year actuarial local recurrence-free survival was 77% [95% CI 63–87]. Variables, including recurrent versus non-recurrent lesions, baseline tumor size, or histology, did not impact long-term outcomes. Twenty-seven percent of patients developed related acute grade 2 or higher toxicities, which resolved with conservative measures. No grade 2 or higher late toxicities were observed. These data support the favorable safety profile of Alpha DaRT, which is currently being explored in a pivotal US trial. [ABSTRACT FROM AUTHOR]