Roche on Tuesday announced that it has received U.S. Food and Drug Administration (FDA) approval for the first companion diagnostic (CDx) test to identify patients with metastatic breast cancer who may be eligible for Enhertu, an HER2-directed antibody drug conjugate.
The Pathway anti-HER2 (4B5) test is the only companion diagnostic test that is FDA-approved for use in the assessment of HER2 status in metastatic breast cancer patients, Roche said.
The test includes a scoring algorithm that helps identify low expressors of HER2, a receptor protein that helps cancer cells grow quickly.
Approximately half of all patients with metastatic breast cancer express low levels of HER2, the firm noted.
Historically, patients who express low levels of HER2 have been classified as HER2-negative and would not have been considered eligible for treatment with HER2-targeting therapies such as Enhertu, which could significantly improve patient outcomes.
The Pathway anti-HER2 (4B5) test was used in the DESTINY-Breast04 trial to identify patients whose tumors expressed low levels of HER2. The trial was sponsored by AstraZeneca and Daiichi Sankyo, the developers of Enhertu. The results showed a 50% reduction in rates of recurrence or death and an overall survival gain of six months over standard of care in patients with low levels of HER2 expression who were treated with Enhertu, Roche said.
