Atezolizumab shows promise in advanced alveolar soft part sarcoma

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The phase 2 study of the anti-PD-L1 agent atezolizumab in patients with advanced alveolar soft part sarcoma (ASPS) has shown promising results, with approximately 37% of patients demonstrating an objective response to treatment.

The trial, which included both adult and pediatric patients with advanced ASPS, administered atezolizumab intravenously at varying dosages based on age, with the highest dose reaching 1200 mg. The treatment schedule followed a 21-day cycle.

Among the 52 patients evaluated, 37% demonstrated an objective response to atezolizumab, including 1 complete response and 18 partial responses. The median time to response was found to be 3.6 months, with responses lasting up to an impressive 55.8 months. The median progression-free survival was 20.8 months, showcasing the potential for extended disease control.

After 2 years of continuous therapy, 7 patients were able to take a treatment break; their responses were sustained beyond this hiatus.

There were no treatment-related grade 4 or 5 adverse events.

Responses to atezolizumab were observed across patients with varying baseline expressions of programmed death 1 and PD-L1, indicating its potential effectiveness across a broad spectrum of cases.

Chen AP, Sharon E, O’Sullivan-Coyne G, et al. Atezolizumab for Advanced Alveolar Soft Part Sarcoma. N Engl J Med. 2023;389(10):911-921. doi: 10.1056/NEJMoa2303383. PMID: 37672694.