Capivasertib, a potential first-in-class AKT inhibitor, + Faslodex shows positive results in CAPItello-291 phase III trial for HR-positive breast cancer

The trial met both primary endpoints, improving PFS in the overall patient population and in a prespecified biomarker subgroup of patients whose tumours had qualifying alterations in the PIK3CA, AKT1 or PTEN genes. Although the overall survival (OS) data were immature at the time of the analysis, early data are encouraging. The trial will continue to assess OS as a key secondary endpoint. The safety profile of capivasertib plus Faslodex was similar to that observed in previous trials evaluating this combination.

Breast cancer is the most common cancer worldwide, with an estimated 2.3 million patients diagnosed in 2020. Approximately 70% of breast cancer tumours are considered HR-positive and HER2-low or negative. Endocrine therapies are widely used for the treatment of HR-positive breast cancer, but many patients with advanced disease develop resistance to 1st-line CDK4/6 inhibitors and estrogen receptor-targeting therapies, underscoring the need for additional options.

Nicholas Turner, MD, PhD, Professor of Molecular Oncology at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, London, UK, and principal investigator in the CAPItello-291 Phase III trial, said: “The CAPItello-291 Phase III trial results show capivasertib offers a clinically meaningful improvement in progression free survival for patients with HR-positive breast cancer. This potential new medicine could give people more time with their cancer under control, which is a priority for patients and their families.

CAPItello-291 :CAPItello-291 is a Phase III, double-blind, randomised trial that is part of a larger clinical programme focused on capivasertib, an investigational AKT (serine/threonine kinase) inhibitor. CAPItello-291 is evaluating the efficacy of capivasertib in combination with Faslodex versus placebo plus Faslodex for the treatment of locally advanced (inoperable) or metastatic HR-positive, HER2-low or negative breast cancer.

The global trial enrolled 708 adult patients with histologically confirmed HR-positive, HER2-low or negative breast cancer whose disease has recurred or progressed during or after aromatase inhibitor therapy, with or without a CDK4/6 inhibitor, and up to one line of chemotherapy for advanced disease. The trial has dual primary endpoints of PFS in the overall patient population and in a subgroup of patients whose tumours have qualifying alterations in the PIK3CA, AKT1 or PTEN genes. In the trial, approximately 40% of tumours had PI3K/AKT/PTEN alterations.