AstraZeneca, Gilead vie for edge in race to treat tough breast cancer

AstraZeneca Plc and Daiichi Sankyo Co. are challenging Gilead Sciences Inc. for dominance in one of the toughest-to-treat breast cancers, with new data from Europe's biggest oncology meeting signaling a high-stakes race for patients - and profits.

Late-stage results presented Sunday showed that both drugs - Astra and Daiichi's Datroway and Gilead's Trodelvy - improved outcomes in patients receiving first-line treatment for metastatic triple-negative breast cancer ineligible for immunotherapy. Datroway extended overall survival by about five months compared with chemotherapy, reducing the risk of disease progression or death by 43%. Trodelvy cut that risk by 38%, though data on overall survival aren't yet complete.

Both sets of findings could change clinical practice, said Ana C Garrido-Castro, an oncologist at Dana-Farber Cancer Institute, who wasn't involved in the trials. "About 25 to 30% of patients do not survive past six months with chemotherapy alone," she said.


Both drugs belong to a newer class known as antibody-drug conjugates - therapies that combine an antibody designed to home in on cancer cells with a potent chemotherapy compound meant to kill them once attached.

Shares in Gilead rose as much as 0.9% in premarket trading on Monday. As of the last close, the stock has risen 33% this year. AstraZeneca climbed as much as 1% in London, bringing the stock's gain this year to about 20%, while Daiichi Sankyo advanced 2.7% in Tokyo on Monday.

Triple-negative breast cancer accounts for about 10% to 15% of all cases and has a five-year survival rate of roughly 77% -below the 91% average for breast cancer overall. Because it lacks the hormone and HER2 receptors that other therapies target, patients have few options once the disease spreads. Even modest survival gains are therefore seen as meaningful.