(Bloomberg) -- AstraZeneca Plc said an experimental cancer drug it’s developing with Daiichi Sankyo Co. did not help breast cancer patients live longer than chemotherapy.
The UK drugmaker said the results for datopotamab deruxtecan, known as Dato-DXd, were probably muddied because patients went on to try other effective therapies after their cancer got worse in the trial. The study looked at people with inoperable or metastatic hormone receptor-positive, HER2-low or negative breast cancer.
Without proof the drug can extend the lives of this group of breast cancer patients, “we believe that approval now looks less likely,” Sean Conroy, an analyst at Shore Capital, wrote in a note. Rival Gilead Sciences Inc.’s drug Trodelvy is already approved for the same patient group and showed it was able to extend lives, Conroy said.
The results were the latest in a series of disappointments for the Astra compound, which earlier this month also reported mixed data in a lung cancer trial. In that study, while the drug helped some sick people live longer, the results didn’t hold true for all patients. Still, more trial results are still to come and may be able to improve the outlook for the drug, Shore’s Conroy said.
Astra shares fell as much as 1.34% in early trading in London. The stock has climbed about 11% this year.
In earlier stages of the breast cancer trial the drug — which was treating patients who had previously been treated with endocrine-based therapy and at least one systemic therapy — had met intermediate targets, such as increasing the length of time patients lived before their cancer got worse.
The drug is an antibody drug conjugate (ADC) which works by ferrying powerful chemotherapy directly to the tainted cells to kill the cancer without damaging the healthy cells.
Astra said it’s still committed to making Dato-DXd an option for breast cancer patients. It said it would share the trial results with drug regulators who are reviewing whether it should be approved.
(Updates with analyst comment in the third paragraph.)
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