Chemotherapy-free approach shows promising tumour response ahead of surgery
Immutep Limited (ASX:IMM; NASDAQ:IMMP) has announced that its novel immunotherapy combination—eftilagimod alpha (efti) with radiotherapy and Merck’s KEYTRUDA® (pembrolizumab)—has met the primary endpoint in a Phase II clinical trial for patients with resectable soft tissue sarcoma (STS).
The EFTISARC-NEO study, conducted at the Maria Skłodowska-Curie National Research Institute of Oncology in Warsaw, demonstrated a significant increase in tumour hyalinisation and fibrosis, a key surrogate marker associated with improved survival outcomes. The median tumour hyalinisation/fibrosis rate for the combination therapy was 50% in preliminary analysis—well above the 35% prespecified benchmark and considerably higher than the 15% typically observed with radiotherapy alone.
Potential paradigm shift for an aggressive orphan cancer
The results are notable as the combination avoids chemotherapy and appears to effectively modulate the tumour microenvironment, which is typically immunosuppressive in STS. Principal investigators Dr Katarzyna Kozak and Dr Paweł Sobczuk said the strong anti-cancer response supports efti’s mechanism of activating antigen-presenting cells and initiating a broad immune cascade.
“This chemotherapy-free combination far exceeded the ambitious target we initially set,” the investigators said. “There remains a very high unmet need in this aggressive orphan cancer indication.”
STS remains a rare cancer with poor prognosis and limited treatment options. The American Cancer Society estimates approximately 13,520 new cases and 5,420 deaths from STS in the US in 2025.
Next steps and broader pipeline
Full results from the 40-patient trial, funded in part by the Polish Medical Research Agency, are expected to be presented later this year at a medical meeting. The trial adds to Immutep’s broader clinical program for efti, which is also being evaluated in solid tumours such as non-small cell lung cancer, metastatic breast cancer, and head and neck squamous cell carcinoma.
Efti, a first-in-class MHC Class II agonist, has received Fast Track designation from the US FDA for use in both NSCLC and head and neck cancer in combination with anti-PD-1 therapies.
