Immutep said that its investigational drug eftilagimod alfa (efti), when combined with MSD’s KEYTRUDA (pembrolizumab), demonstrated a median overall survival of 17.6 months in patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) and low PD-L1 expression.
This finding, from the Phase IIb TACTI-003 trial, significantly exceeds survival rates seen with existing standard treatments in this patient group.
The trial included 31 evaluable patients and marked its data cut-off on 31 March 2025.
The reported median overall survival for this cohort surpasses those achieved through current standard-of-care therapies for similar patients. Cetuximab plus chemotherapy and anti-PD-1 therapy plus chemotherapy showed median survival periods of 10.7 and 11.3 months, respectively.
Anti-PD-1 monotherapy yielded an even lower median survival of 7.9 months.
The findings address a critical need within the first-line HNSCC patient population characterised by low PD-L1 expression (CPS <1), a group that comprises approximately 20% of cases and faces limited treatment options.
Currently, regulatory approvals restrict anti-PD-1 monotherapy usage to patients expressing higher PD-L1 levels, leaving chemotherapy-inclusive regimens as the main available treatments for those with CPS <1.
Immutep CEO Marc Voigt said: “We are excited to see this strong survival benefit for head and neck cancer patients with such cold tumours. Combining these two complementary immunotherapies has led to a 7-fold increase in response rates and a more than doubling of median overall survival as compared to historical results from anti-PD-1 monotherapy.
“Driving durable responses that translate into clinically meaningful survival holds tremendous promise for these patients in need of more tolerable and efficacious therapies.”
Immutep highlights the continued favourable safety profile of the efti and pembrolizumab combination, noting no new safety concerns. These results build on earlier evidence showing high response rates and several complete responses among the treated cohort.
Eftilagimod alfa has received fast track designation from the US Food and Drug Administration (FDA) for first-line treatment in both HNSCC and non-small cell lung cancer (NSCLC).
The company is preparing to engage with the FDA to explore potential approval pathways for efti targeting first-line HNSCC patients with low PD-L1 expression. Immutep continues data collection and analysis as part of the ongoing TACTI-003 trial, with further updates anticipated later this year.
Eftilagimod alfa functions as an MHC Class II agonist that stimulates both innate and adaptive immunity by activating antigen-presenting cells. This activation promotes the proliferation and activation of multiple immune cells, including CD8+ cytotoxic T cells, CD4+ helper T cells, dendritic cells, NK cells, and monocytes.
Additionally, it enhances the production of immune mediators such as IFN-ƴ and CXCL10, which play roles in boosting the immune system’s capacity to combat cancer.
Beyond HNSCC, efti is being evaluated across various solid tumour types including NSCLC and metastatic breast cancer, demonstrating its potential versatility in oncology therapy.
