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Immutep Launches Phase II/III Trial in HER2-Low Metastatic Breast Cancer

NEW YORK – Immutep on Tuesday said it began a Phase II/III trial of its LAG-3 immunotherapy candidate eftilagimod alpha with paclitaxel in patients with HER2-negative or -low metastatic breast cancer.

In the open-label lead-in portion of the Phase II AIPAC-003 trial, investigators will test eftilagimod at a 90 mg dose in combination with paclitaxel in up to 12 patients. Following that, researchers will establish the optimal biological dose by randomly assigning 58 patients to either the 30 mg or 90 mg dose of eftilagimod plus paclitaxel. If all goes well, Sydney-based Immutep will initiate a randomized, double-blinded placebo-controlled Phase III trial of the combination in 771 patients, in which overall survival would be the primary endpoint.

Based on feedback from the US Food and Drug Administration and the European Medicines Agency, Immutep expanded the trial design to include patients with triple-negative breast cancer and added the open-label lead-in portion to the trial. With these changes, the company expects to produce data from the trial that will support a biologics license application and a European marketing authorization application. 

Eftilagimod is a soluble LAG-3 protein targeting MHC Class II ligands on antigen-presenting cells. It is designed to activate those cells to trigger an immune response targeting the cancer. In a Phase IIb trial, Immutep-treated patients saw a 2.9-month increase in median overall survival, a 48 percent overall response rate, and a statistically significant increase in cytotoxic CD8 T cells correlated with improved overall survival.

In a statement, Immutep CEO Marc Voigt said that the "selected Phase II/III trial design allows us to move forward with a risk-balanced approach in [metastatic breast cancer] as we continue our prioritized late-stage clinical development with anti-PD-1 therapy in first-line head and neck squamous cell carcinoma and first-line non-small cell lung cancer."