Eftilagimod Alpha Plus Paclitaxel Yields Overall Survival Benefit in Metastatic HR+ Breast Cancer

Patients with hormone receptor–positive breast cancer in 3 separate subgroups showed an overall survival benefit when treated with eftilagimod alpha plus paclitaxel compared with the placebo.

Results of the phase 2b AIPAC study (NCT02614833) in patients with metastatic hormone receptor–positive breast cancer showed significant improvements in overall survival (OS) in those who were treated with eftilagimod alpha (Efti) plus paclitaxel versus matched placebo, according to data presented at the 2021 Society for Immunotherapy of Cancer (SITC) Annual Meeting. 

Data showed patients in the efti group had a median OS of 20.4 months compared with 17.5 months in the comparator group, for a survival benefit of 2.9 months (HR, 0.88; P = .197). The minimum follow-up was 22 months.

“These very pleasing results give us additional confidence that efti can ultimately deliver a meaningful clinical improvement for diverse sets of cancer patients. The results from our AIPAC trial are especially pleasing because metastatic breast cancer patients in the chemotherapy setting are a difficult to treat and large patient population where immunotherapies often fail to provide an additional benefit. These supportive results are also timely as we solidify the trial design for our planned phase 3 study in metastatic breast cancer, subject to regulatory body interactions,” Marc Voigt, CEO of Immutep, said in a press release.

A total of 227 patients with HER2-negative, HR-positive metastatic breast cancer were randomized 1:1 in a fasion. There were 114 patients in the efti group and 113 patients in the comparator group of placebo and paclitaxel. 

Patients received weekly paclitaxel on days 1, 8, and 15. On days 2 and 16 of each 4-week cycle, efti or placebo was injected with treatment repeated for up to 6 cycles. After the cycles, patients progressed to maintenance therapy with efti alone.

Those younger than 65 years had a median OS of 22.3 months in the efti group vs 14.8 months in the comparator group (HR, 0.66; P = .017), with a survival benefit of 7.5 months. Patients in the low monocyte group had a median OS of 32.5 months in the efti group and 12.9 months in the comparator group (HR, 0.44; P = .008), with a survival benefit of 19.6 months. Patients who had luminal B cancer had a median OS of 16.8 months in the efti group and 12.6 months in the comparator group (HR, 0.67; P = .049), with a survival benefit of 4.2 months.

In this trial, patients did not experience any new safety signals and the combination was deemed to be safe and well tolerated. Moving forward, investigators are planning a phase 3 investigation of efti plus paclitaxel for patients with metastatic breast cancer across multiple countries.

Reference

Immutep reports improved and statistically significant survival benefit for three key patient groups in final phase IIIb AIPAC study results in metastatic breast cancer. News Release. Immutep. November 9, 2021. Accessed November 15, 2021. https://bit.ly/3kCKABU