Immutep Shares Safety Data from AIPAC-003 at ESMO Breast 2024

Immutep Limited, a clinical-stage biotechnology company, has announced promising results from the AIPAC-003 Phase II/III trial involving their novel LAG-3 immunotherapy, eftilagimod alpha (efti), combined with paclitaxel. These findings were presented at the European Society for Medical Oncology (ESMO) Breast Cancer 2024 Congress.

The trial includes the first-ever 90mg dosing of efti, a soluble LAG-3 protein and MHC Class II agonist, administered alongside weekly paclitaxel. Key results show a notable response in six patients with metastatic breast cancer (MBC) who had exhausted other treatment options, including endocrine therapy and CDK4/6 inhibitors.

Efficacy Results

The study revealed a 50% overall response rate among the six patients, with one complete response (CR) and two partial responses (PR). Additionally, a 100% disease control rate was observed, as three patients achieved stable disease according to RECIST 1.1 criteria. These findings are detailed in a poster titled “Testing a higher dose (90 mg s.c.) of eftilagimod alpha, a soluble LAG-3 protein, in metastatic breast cancer patients receiving weekly paclitaxel in AIPAC-003”.

Case Study: Complete Response

A noteworthy case involves a patient diagnosed with triple-negative breast carcinoma (TNBC) in 2019, who did not respond to multiple lines of therapy, including a CDK 4/6 inhibitor. This patient achieved a partial response during the combination treatment of efti and paclitaxel, which later advanced to a complete response. Remarkably, this complete response has been maintained since the patient transitioned to efti monotherapy, discontinuing paclitaxel.

Safety and Pharmacodynamic Data

The lead-in phase of the trial highlights the favorable safety profile of the 90mg efti dosing. No dose-limiting toxicities or severe treatment-emergent adverse events (grade 3 or higher) were reported. Pharmacokinetic data indicates that the 90mg dose results in a higher maximum concentration of efti in the bloodstream compared to lower doses used in previous trials. Efti remains at a pharmacologically active level up to 96 hours post-administration.

Additionally, pharmacodynamic effects were observed, including an increase in immune cell levels such as CD8 and CD4 T cells, and elevated plasma Th1 biomarker levels. All patients demonstrated a significant increase in interferon-gamma (IFN-γ) levels and the majority showed a marked rise in CXCL10 levels after a single 90mg dose of efti.

Expert Commentary

Dr. Serafin Morales Murillo from the University Hospital Arnau de Vilanova in Spain, who is also an investigator in the AIPAC-003 trial, expressed optimism about these findings. He emphasized the significance of the high response and disease control rates in patients whose cancer had progressed following various therapies, including CDK 4/6 inhibitors. Dr. Murillo looks forward to further data from this study.

Future Directions

The randomized Phase II portion of the AIPAC-003 trial, which aims to compare the efficacy of 90mg versus 30mg dosing of efti, is ongoing, with 35 patients enrolled thus far out of a planned 58. This part of the trial is crucial for determining the optimal dose in alignment with the FDA’s Project Optimus initiative. Additional safety and efficacy data from the trial are anticipated in 2024.

About Eftilagimod Alpha (Efti)

Efti is Immutep’s proprietary soluble LAG-3 protein and MHC Class II agonist that boosts both innate and adaptive immunity. It is designed to activate various immune cells, enhancing the body’s ability to combat cancer. Efti is being evaluated for multiple types of solid tumors and has received Fast Track designation from the FDA for first-line treatment of head and neck squamous cell carcinoma (HNSCC) and non-small cell lung cancer (NSCLC).

About Immutep

Immutep is a leader in developing LAG-3 immunotherapies for cancer and autoimmune diseases. The company’s innovative approach leverages their expertise in LAG-3 to provide new therapeutic options for patients, aiming to maximize benefits for both patients and shareholders.

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