Potential Mechanisms for Immunotherapy Resistance in Adult Soft-Tissue Sarcoma

Soft-tissue sarcomas represent a diverse group of rare malignancies originating from mesenchymal tissue, accounting for less than 1% of adult cancers in the USA. With over 13,000 new cases and around 5350 deaths annually, patients with metastatic soft-tissue sarcomas face limited therapeutic options and an estimated median overall survival of 18 months. While immunotherapy has demonstrated effectiveness in several cancers, its application in soft-tissue sarcomas remains challenging owing to the tumors' largely "cold" immunological environment, characterized by low levels of tumor-infiltrating lymphocytes and a lack of soft-tissue sarcoma-specific biomarkers. This review examines potential mechanisms underlying immunotherapy resistance in soft-tissue sarcomas, including the complex interplay between innate and adaptive immunity, the tumor microenvironment, and the role of immune-related genes. Despite preliminary findings suggesting correlations between immune profiles and histological subtypes, consistent biomarkers for predicting immunotherapeutic responses across soft-tissue sarcoma types are absent. Emerging strategies focus on converting "cold" tumors to "hot" tumors, enhancing their susceptibility to immunologic activation. While research is ongoing, personalized treatment approaches may offer hope for overcoming the inherent heterogeneity and resistance seen in soft-tissue sarcomas, ultimately aiming to improve outcomes for affected patients.