Immutep (ASX:IMM) has reported promising early results from its Phase 2 EFTISARC-NEO trial, with new data presented at the 2025 Connective Tissue Oncology Society (CTOS) Annual Meeting in Florida.
The study, which is evaluating the company’s immunotherapy eftilagimod alfa (efti) in combination with radiotherapy and MSD's KEYTRUDA (pembrolizumab) for resectable soft tissue sarcoma, significantly exceeded its prespecified pathologic response target.
In 38 evaluable patients, the combination achieved a median tumour hyalinization and fibrosis rate of 51.5 per cent, a level that met the study’s primary endpoint with strong statistical significance. Researchers noted that this response rate is more than three times higher than historical outcomes with standard radiotherapy alone.
The trial enrolled patients with ten soft tissue sarcoma subtypes, including highly aggressive and rare forms such as myxofibrosarcoma, undifferentiated pleomorphic sarcoma and malignant peripheral nerve sheath tumours. Early translational results from the first 20 surgical patients showed robust immune activation consistent with efti’s mechanism of action. Statistically significant increases were seen in circulating cytokines and chemokines, including CXCL9, CXCL10, IL-23 and interferon-gamma. Investigators reported that rises in these immune-response biomarkers correlated with stronger pathologic responses, suggesting deeper anti-tumour activity ahead of surgery.
Trial investigator Dr Paweł Sobczuk described the findings as an encouraging signal in a difficult-to-treat cancer. He noted that the breadth of activity across multiple subtypes supports the potential of efti’s antigen-presenting-cell activation to drive both innate and adaptive immune responses. Dr Sobczuk also highlighted the recent Golden Scalpel Award granted to the study, an accolade reserved for highly innovative medical research in Poland.
Immutep’s chief scientific officer, Dr Frédéric Triebel, said the sustained increase in immune biomarkers observed two weeks after efti injection reflects a meaningful and coordinated immune response. He noted that the strength of the early data suggests possible applications for efti in earlier-stage cancers where tumour burden is lower and curative treatment is still the primary goal.
Soft tissue sarcoma remains an orphan cancer with poor outcomes and significant unmet clinical need. Future readouts from EFTISARC-NEO will include disease-free and overall survival results as the dataset matures. Further translational analyses are also underway to better understand the immunologic drivers of response.