Dr. Wildiers on the Final Results of the AIPAC Trial in HR+/HER2- Metastatic Breast Cancer

Hans Wildiers, MD, medical oncologist, Department of Medical Oncology, full professor, Faculty of Medicine, member, Laboratory of Experimental Oncology, University Hospital Leuven, Leuven, Belgium, discusses the final results of the phase 2b AIPAC trial (NCT02614833) in hormone receptor (HR)–positive, HER2-negative metastatic breast cancer.

The AIPAC trial randomized 227 patients with HR-positive, HER2-negative metastatic breast cancer to eftilagimod alpha (efti) plus paclitaxel followed by efti maintenance vs paclitaxel plus placebo followed by placebo maintenance. Most patients (84.1%) were endocrine resistant and 44.2% of patients received prior CDK4/6 inhibition.

The results of the study, which were presented during the 2021 SITC Annual Meeting, failed to demonstrate a statistically significant improvement in overall survival (OS) with efti vs placebo in this patient population. However, in patients aged less than 65 years, the median OS was 22.3 months with efti vs 14.8 months with placebo. In patients pre-treated with CDK4/6 inhibitors, the median OS was 20.2 months vs 14.9 months, respectively.

Moreover, the addition of efti to paclitaxel significantly increased pre-dose CD8 T cells compared with placebo plus paclitaxel and the increase correlated with increased OS.

Regarding safety, the most common efti-related adverse effect observed was any kind of local injection-related reaction, which was reported in 65.8% of patients who received efti vs 11.6% of patients who received placebo. Moreover, no deterioration in quality of life (QOL) was observed with efti; however, patients who received placebo experienced a significant deterioration in QOL at 6 months, concludes Wildiers.