Immutep announces initiation of Phase 2/3 trial of 'efti' in metastatic breast cancer

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Immutep (ASX:IMM) has announced the initiation of the AIPAC-003 Phase 2/3 clinical trial of its eftilagimod alpha in combination with paclitaxel for treating metastatic HER2-neg/low breast cancer.

That Australian clinical-stage biotechnology company is developing novel LAG-3 immunotherapies for cancer and autoimmune disease.

The company said its first-in-class soluble LAG-3 protein (efti), targeting MHC Class II ligands on antigen-presenting cells (APC), is positioned to improve clinical outcomes from standard-of-care chemotherapy.

It said its activation of APCs triggers a broad immune response, including significant increases in cytotoxic CD8+ T cells armed with chemo-induced tumour antigens to target cancer.

"This synergy was demonstrated by the AIPAC Phase IIb trial’s encouraging efficacy and safety, including a +2.9-month median overall survival (mOS) improvement, statistically significant mOS improvements between 4.2 to 19.6 months across three pre-specified subgroups, a statistically significant increase in cytotoxic CD8 T cells that correlated with improved OS, a higher 48% ORR (vs 38% for chemo alone), and a superior Quality of Life preservation," it said.

CEO Marc Voigt said, “With its novel mechanism of action to activate antigen-presenting cells, efti has to date safely improved clinical outcomes from anti-PD-(L)1 therapies and standard-of-care chemotherapy.

"We look forward to AIPAC-003 building upon the encouraging synergy seen in our previous Phase IIb trial in metastatic breast cancer, especially with its three key adaptations: same-day administration of efti plus paclitaxel, this dual IO-chemotherapy treatment continuing until disease progression, and a new primary endpoint of overall survival.

"The selected Phase II/III trial design allows us to move forward with a risk-balanced approach in MBC, as we continue our prioritized late-stage clinical development with anti-PD-1 therapy in 1st line head & neck squamous cell carcinoma and 1st line non-small cell lung cancer.”

The company said it and the US FDA agreed to the integrated Phase II/III trial design for AIPAC-003 to help inform a Biologics License Application.

The open-label lead-in of up to 12 patients will be followed by a randomized (1:1) portion of the Phase II consisting of up to 58 patients receiving 30mg efti or 90mg efti to determine the optimal biological dose in combination with paclitaxel. The company said that depending on the Phase 2 results, potential regulatory actions and resources, a randomised, double-blinded, placebo-controlled Phase 3 portion will then follow.