Enhertu reduced disease progression or death by 72% vs. a currently approved treatment, the company said in a statement.
A Phase 3 trial showed that its antibody drug conjugate demonstrated "superior progression-free survival" in patients with breast cancer when compared with trastuzumab emtansine. That drug is currently approved to treat patients with HER2-positive unresectable and/or metastatic breast cancer.
A "high and consistent benefit" was "seen across efficacy endpoints and key subgroups of patients receiving Enhertu in [the Destiny-Breast03 trial]," the company said.
The results "support the potential of Enhertu to become the new standard of care for those who have previously been treated for HER2-positive metastatic breast cancer," Javier Cortes, who heads the International Breast Cancer Center, said in the company statement. Cortes is principal investigator for the DB03 study,
Shares of AstraZeneca at last check jumped 4.6% to $58.10 on a broadly lower day on the stock market. On July 12 the stock touched a 52-week high near $61.
Susan Galbraith, the company's oncology executive vice president, said the drug tripled progression-free survival with a disease control rate exceeding 95%.
Early survival data showed nearly all patients treated with Enhertu were alive after a year, a positive indication of the treatment's potential.
The safety profile of the most common adverse events from the treatment were consistent with the company's previous clinical trials.
The most common grade 3 or higher treatment event included neutropenia -- lower white blood cell count -- which occurred in nearly 20% of patients.