Immutep reports positive EFTISARC-NEO phase II trial results in soft tissue sarcoma

Immutep Limited has announced positive data from the EFTISARC-NEO Phase II trial, presented at the 2025 European Society of Medical Oncology (ESMO) Congress in Berlin. The investigator-initiated study evaluated eftilagimod alfa (efti) in combination with radiotherapy and KEYTRUDA® (pembrolizumab) in the neoadjuvant setting for resectable soft tissue sarcoma (STS).

The primary endpoint of the study was met, with the novel combination treatment achieving a median of 51.5% tumor hyalinization/fibrosis in the evaluable patient population (N=38), which was statistically significant (p<0.001). This result substantially exceeded the study's predefined target of 35% and is more than threefold higher than historical results from radiotherapy alone.

Tumor hyalinization and fibrosis are recognized as early surrogate endpoints correlated with improved overall survival and recurrence-free survival in STS patients. The positive results were observed across multiple STS subtypes, suggesting broad applicability of the combination therapy.

The treatment regimen demonstrated a favorable safety profile, with only one Grade ≥3 toxicity related to immunotherapy reported. These findings may pave the way for a new therapeutic option for patients with STS, a disease with significant unmet medical need.

Immutep has thanked the principal investigators, patients, and their families for participating in this trial. Soft tissue sarcoma is an orphan disease with a generally poor prognosis, and new treatment modalities are crucial.