Immune checkpoint inhibition resulted in mostly moderate activity in patients with cardiac soft-tissue sarcomas, according to a multicenter retrospective analysis reported by Nassar et al in JACC: CardioOncology. Investigators included 24 patients with cardiac soft-tissue sarcomas treated with anti–PD-1–based therapy between 2015 and 2022. At the time of immune checkpoint inhibitor–based treatment, 75.0% (n = 18) of patients had metastatic cardiac soft-tissue sarcomas and 16.7% (n = 4) had locally advanced disease. Immune checkpoint inhibitors were administered as first-line therapy in 25.0% (n = 6) and as second-line therapy or beyond in 75.0% (n = 18). Among 18 patients with available response data, objective response occurred in 2 (11.1%, 95% confidence interval [CI] = 3.1%–33.0%). Among 22 patients with advanced or metastatic disease, median progression-free survival was 5.7 months (95% CI = 2.8–13.3 months) and median overall survival was 14.9 months (95% CI = 5.7–23.7 months). Compared to 15 patients with nonangiosarcoma cardiac soft-tissue sarcomas, 8 patients with cardiac angiosarcoma had significantly poorer median progression-free survival (1.7 vs 11 months, P < .0001) and median overall survival (3.0 vs 24.0 months, P = .008). The investigators reported that any-grade treatment-related adverse events occurred in 46.7% (n = 7/15) of patients with nonangiosarcoma cardiac soft-tissue sarcomas (40% were grade ≥ 3 events); whereas no treatment-related adverse events of any grade occurred in patients with angiosarcoma. The study authors concluded: “Although immune checkpoint inhibitors demonstrated modest activity in cardiac soft-tissue sarcomas, durable benefit was observed in a subset of patients with nonangiosarcoma, albeit with higher toxicity.”