Promising new treatment for patients with HR+ HER-2 negative metastatic breast cancer

June 11, 2024
Breast cancer that has spread to other parts of the body (metastatic) is particularly hard to treat.

New research from Yale Cancer Center reveals data from a phase I study in patients with hormone receptor positive HER2-negative metastatic breast cancer. The results, which assess the safety and efficacy of a treatment known as PF-07248144, offer new hope for treating this aggressive type of breast cancer. 

Yale researchers found that PF-07248144, both as a standalone therapy and in combination with the hormone therapyfulvestrant (an estrogen receptor antagonist agent), was well-tolerated and effective at treating patients with hormone receptor-positive, HER2-negative metastatic breast cancer. PF-07248144 targets and blocks the proteins KAT6A and KAT6B, which can help cancer grow and spread when they are not working properly or are dysregulated. 

Senior author of the study, Patricia LoRusso, DO, Associate Director for Experimental Therapeutics at Yale Cancer Center, presented the findings at the American Society of Clinical Oncology (ASCO) Annual Meeting on June 1. The results of the study were published on the same day in Nature Medicine. 

For nearly three years, 107 patients were enrolled in the phase I trial and received at least one dose of PF-07248144. 29 patients received PF-07248144 at 5 dose levels, 35 patients received PF-07248144 at 5mg daily, and 43 patients received PF-07248144 at 5 mg daily in combination with 500 mg fulvestrant. According to LoRusso, the goal of the study was to overcome the patients ESR1 mutation and enhance or resume response in combination with hormonal therapy (fulvestrant). 

In a review of the data, the combination of PF-07248144 with fulvestrant showed an objective response rate (ORR) of 30.2% and a median duration of response (DOR) of nine months. For patients who were treated with only PF-07248144, the ORR was lower at 11%, however the median DOR was slightly better at 12 months. Most side effects related to the treatment were manageable. The most common were taste alteration, a decrease in white blood cell count, and anemia.