Everolimus breast cancer trial halted early with primary end point met

Novartis announced that it has stopped early its phase 3 trial of everolimus(Afinitor) plus exemestane in women with estrogen receptor-positive locally-advanced or metastatic breast cancer after an interim analysis showed that the primary end point of progression-free survival was met.

The Breast cancer trials of OraL EveROlimus-2 (BOLERO-2) study was investigating everolimus in combination with exemestane versus placebo plus exemestane in postmenopausal women with estrogen receptor-positive locally-advanced or metastatic breast cancer, whose disease had progressed, despite treatment with the nonsteroidal aromatase inhibitors letrozole or anastrozole.

The study enrolled more than 700 patients at more than 195 sites worldwide who had received no more than 1 prior chemotherapy treatment for advanced breast cancer. Patients were randomly assigned (2:1) to receive continuous therapy with everolimus 10 mg/day orally or placebo plus oral exemestane 25 mg/day. The primary end point was progression-free survival. Secondary end points included overall survival, overall response rate, incidence of adverse events, patient-reported outcomes, and clinical benefit rate. The company did not mention the results of the secondary end points, but said that results would be presented at an upcoming medical conference and that the company is planning to file marketing applications worldwide by the end of the year.

Everolimus targets mTOR in cancer cells, a protein that acts as an important regulator of tumor cell division, blood vessel growth, and cell metabolism. The drug can cause serious side effects including lung or breathing problems, infections, and renal failure, which can lead to death. Mouth ulcers and mouth sores are common side effects, the company stated.

"Despite clinical progress in advanced breast cancer, most women are either initially resistant or develop resistance to endocrine therapy over time. As a result, there is a significant need for new treatment options," said Hervé Hoppenot, president, Novartis Oncology, in a company statement. "Based on these study results, this combination has the potential to extend the time until chemotherapy is needed for these patients."