Advances in alveolar soft part sarcoma treatment in the era of immunotherapy

Alveolar soft part sarcoma (ASPS), an ultra-rare sarcoma, is a highly vascularized soft tissue tumor with ASPSCR1::TFE3 gene fusion that frequently metastasizes to the lungs, bones, and brain. The efficacy of conventional chemotherapy for ASPS is limited; however, targeted agents, especially vascular endothelial growth factor receptor (VEGFR) inhibitors, such as pazopanib and cediranib, have shown clinical efficacy. Unlike other soft tissue sarcomas, ASPS has been suggested to be in an immune hot state, that is, the tumor microenvironment contains a substantial number of immune cells, indicating it could be more responsive to immunotherapy. Recently, immune checkpoint inhibitors (ICIs), such as pembrolizumab, nivolumab, and atezolizumab, have emerged as promising treatment strategies, demonstrating higher response rates than conventional chemotherapy or targeted therapy. In addition, studies have suggested that combination therapies, including VEGFR inhibitors and ICIs, yield high response rates and prolong progression-free survival. This review summarizes and discusses recent advances in ASPS treatment, focusing on the role of immunotherapy. A combined treatment approach using VEGFR inhibitors and ICIs represents a promising therapeutic strategy, particularly for ASPS, which is generally resistant to conventional cytotoxic anticancer drugs.