Immutep delivers strong survival results in efti-Keytruda head and neck cancer immunotherapy trial

Immutep (ASX: IMM) has announced a solid median overall survival (OS) rate in Cohort B of its TACTI-003 (Keynote-C34) Phase IIb trial to treat patients with recurrent or metastatic head and neck squamous cell carcinoma (1L HNSCC).

The study, which evaluated eftilagimod alfa (efti) in combination with anti-PD-1 therapy Keytruda (pembrolizumab) as first-line therapy for patients who have a PD-L1 protein expression below 1 (combined positive score, CPS <1), demonstrated an OS of 17.6 months.

Immutep’s study found that efti in combination with pembrolizumab continues to be well tolerated, with no new safety signals.

Standalone therapy

Up to 20% of patients with 1L HNSCC have a CPS of <1 and, despite immunotherapy’s progress in fighting cancer, anti-PD-1 therapy alone (without chemotherapy) is only approved for patients who express PD-L1 (or CPS >1).

Additionally, all available treatment options for patients with PD-L1 CPS <1 include chemotherapy.

The safety and mature OS data from this latest study build on a positive high overall response rate, with multiple complete responses achieved through combining both immunotherapies in 1L HNSCC patients with CPS <1.

Strong survival benefit

Immutep chief executive officer Mark Voigt said the study showed a strong survival benefit for head and neck cancer patients with cold (or immune-resistant) tumours.

“Combining these two complementary immunotherapies has led to a sevenfold increase in response rates and a doubling of the median overall survival as compared to historical results from anti-PD-1 monotherapy,” he said.

“Driving durable responses that translate into clinically meaningful survival holds tremendous promise for these patients in need of more tolerable and efficacious therapies.”

Unmet medical need

The study results supported a patient group with high unmet medical need.

“There is a lack of approved immunotherapy-only treatment regimens and a lack of competitor trials with chemotherapy-free approaches targeting this patient population,” Mr Voigt said.

“Given the strength of the efficacy and safety results generated to date with efti in combination with pembrolizumab, we will meet with regulators to discuss next steps and potential paths to approval.”

Adaptive immunity

Efti is Immutep’s proprietary soluble LAG-3 protein and MHC (major histocompatibility complex) Class II agonist that stimulates innate and adaptive immunity for the treatment of cancer.

Efti – which Immutep is evaluating for the treatment of solid tumours including HNSCC, non-small cell lung cancer (NSCLC) and metastatic breast cancer – has a favourable safety profile enabling various treatment combinations with anti-PD-\[L]1 immunotherapy and chemotherapy.

It has previously received fast-track designation in first-line HNSCC and first-line NSCLC from the US Food and Drug Administration.