Immutep to present data from AIPAC-003 Phase II trial

Immutep (IMMP) announces new data from the AIPAC-003 trial will be presented at the 2025 San Antonio Breast Cancer Symposium taking place in San Antonio, Texas, from December 9-12, 2025. The Phase II study randomised female participants with HR+ and HER2-negative/HER2-low metastatic breast cancer resistant to endocrine-based therapy including cyclin-dependent kinase 4/6 inhibitors or metastatic triple-negative breast cancer not eligible for PD-(L)1-based therapy. Patients were randomised 1:1 to receive either 30 or 90 mg eftilagimod alfa in combination with paclitaxel to determine the optimal biological dose consistent with the FDA’s Project Optimus initiative. Both efti dosing levels on top of weekly paclitaxel in heavily pretreated metastatic breast cancer patients, who received a median of three prior lines of systemic therapy, led to strong objective response rates and disease control rates of 41.9% and 87.1% and 48.5% and 78.8%, respectively, in the evaluable population. Time to onset of response was comparable at 2.0 months versus 1.9 months. Additionally, both dosing levels elicited the desired pharmacodynamic response in line with efti’s mechanism of action with substantial increases in immune activation biomarkers including absolute-lymphocyte count and interferon-gamma. Data cut-off date for efficacy results was 15 September 2025.