• Novel combination with eftilagimod alfa (efti) achieves 51.5% tumour hyalinization/fibrosis in soft tissue sarcoma
• Strong immune system activation observed with increases in key cytokines and chemokines
• Pathologic responses correlate with increased immune biomarkers, indicating potential for improved survival

Immutep Limited has announced positive data from the EFTISARC-NEO Phase II trial, which were presented at the Connective Tissue Oncology Society (CTOS) 2025 Annual Meeting. The investigator-initiated study evaluated eftilagimod alfa (efti) in combination with radiotherapy and pembrolizumab in the neoadjuvant setting for resectable soft tissue sarcoma (STS). In the evaluable patient population (N=38), the novel combination with efti achieved a median 51.5% tumour hyalinization/fibrosis, significantly exceeding the study's prespecified level of pathologic response rates. These promising results were observed across ten different STS subtypes, including rare and highly aggressive tumours with poor prognosis. Early translational data from the initial twenty patients showed a strong immune system activation in line with efti's mode of action, with statistically significant increases in the expression of key cytokines and chemokines, such as CXCL9, CXCL10, IL-23, and IFN-γ. The increase in immune response biomarkers like IFN-gamma correlated with pathologic responses, indicating a significant destruction/alteration of tumour tissue following treatment. The high levels of tumour hyalinization/fibrosis achieved may hold significance in terms of future outcomes, as it serves as an early surrogate endpoint correlated with enhanced overall survival and recurrence-free survival in STS patients. Disease-free survival and overall survival data are still immature and will be presented in the future.

As neoadjuvant immunotherapy becomes more established in the treatment of early-stage cancers, the findings from EFTISARC-NEO highlight the possibility for efti to be used in patients who have a lower tumor burden at diagnosis. This could expand the range of patients who might benefit from efti, potentially increasing its role in the treatment landscape for cancers that are still localized and resectable.