SILVER SPRING, Maryland: A significant shift in the treatment of HER2-positive breast cancer is underway in the United States, after regulators cleared a new combination therapy for use at the very start of care.

The U.S. Food and Drug Administration this week approved AstraZeneca and Daiichi Sankyo's cancer drug Enhertu, in combination with Roche's Perjeta, as a first-line treatment for patients with a form of advanced breast cancer.

Enhertu was initially approved in the U.S. in late 2019 as a third-line therapy for patients with HER2-positive breast cancer who had already undergone other treatments.

Under the expanded approval, Enhertu can now be used alongside Roche's Perjeta to treat adults with advanced HER2-positive breast cancer confirmed through an FDA-approved diagnostic test.

Enhertu, which is also approved for certain gastric and lung cancers, is an antibody-drug conjugate designed to deliver chemotherapy directly to HER2-positive cancer cells, limiting damage to healthy tissue.

Roche's Perjeta, developed by Genentech, was first approved in June 2012 for use with trastuzumab and chemotherapy in patients with previously untreated HER2-positive metastatic breast cancer.

The FDA also cleared two companion diagnostic tests to identify patients with HER2-positive breast cancer who are eligible for treatment with the Enhertu-Perjeta combination.

The approval was based on data from a clinical study involving 1,157 patients with advanced HER2-positive breast cancer who had not previously received chemotherapy for metastatic disease.

Patients treated with the Enhertu and Perjeta combination achieved a median progression-free survival of 40.7 months, compared with 26.9 months for those receiving the standard treatment.

In the trial, tumors shrank or disappeared in 87 percent of patients receiving the new combination, versus 81 percent among patients given standard therapy.

Overall survival data were not yet mature at the time of analysis, with 16 percent of patients having died across both treatment groups.