Angiosarcoma: Role of Immunotherapy.

Opinion statement: Recent clinical trials have investigated immune checkpoint inhibitors (ICIs) alone, in combination with tyrosine kinase inhibitors (TKIs), or with chemotherapy in angiosarcoma, yielding mixed results across subtypes. Single-agent ICI therapy, such as cemiplimab (ORR 27.8%), has shown responses primarily in UV- and radiation-associated angiosarcomas, likely due to their higher tumor mutation burden (TMB), while dual ICI therapy (SWOG S1609, ORR 25%) suggests potential benefit but remains limited in cutaneous disease. ICI-TKI combinations, such as cabozantinib plus nivolumab (Alliance A091902, second-line, ORR 59%), demonstrated significant efficacy in both cutaneous and non-cutaneous angiosarcomas, suggesting anti-angiogenic therapy may enhance ICI responses in tumors historically resistant to checkpoint blockade. ICI-chemotherapy combinations have been less consistent. The Alliance A091902 first-line trial (paclitaxel ± nivolumab) found no overall PFS benefit, though scalp/face angiosarcoma patients appeared to fare better, raising the question of whether ICI alone might be equally effective in this subset. The South Korean paclitaxel + avelumab trial (ORR 50%) showed promising response rates, but the lack of detailed subgroup analysis limits interpretation. Other chemotherapy-ICI combinations, such as doxorubicin plus pembrolizumab, have shown isolated responses but require further study in larger cohorts. Moving forward, better biomarkers are critical for identifying which patients benefit most from ICIs, and while TKI-ICI combinations appear to hold the most promise, chemotherapy-ICI strategies need further refinement to optimize sequencing and patient selection in angiosarcoma treatment.