LONDON — AstraZeneca announced on Thursday that a cancer drug in development had not shown as much progress as expected, a setback for the pharmaceutical company, which is grappling with weak sales and competition from manufacturers of generics.
The treatment for lung cancer had been expected to be a major driver of growth for AstraZeneca. Like many of its rivals, the company faces increased pressure from manufacturers that capitalize on the loss of patent protections on best-selling medicines.
The trial’s disappointing results sent shares in AstraZeneca plummeting nearly 16 percent, to about $56.
The company said on Thursday that the trial of the drug, known as Mystic, had not met a “primary endpoint” and would not have met a secondary target. Sean Bohen, executive vice president and chief medical officer at AstraZeneca, said in a statement that the results were “disappointing.”
AstraZeneca, a British-Swedish company, fended off a $119 billion takeover attempt from an American rival, Pfizer, in 2014, arguing that it had promising drugs in the pipeline. At the time, analysts said that the lung cancer drug could be worth as much as $6 billion in annual sales, and Pfizer had identified potential treatments for cancer as one of the assets that had attracted it to the company.
AstraZeneca agreed in December 2015 to pay $4 billion for a majority stake in Acerta Pharma, a privately held cancer drug developer with operations in the Netherlands and in California. The company has also bought ZS Pharma, a California-based maker of drugs for chronic kidney disease and heart failure, for $2.7 billion, and it acquired the respiratory business of the Takeda Pharmaceutical Company of Japan for $575 million.
AstraZeneca’s challenge is illustrated by the fate of the anti-cholesterol pillCrestor, which was prescribed more than 20 million times in the United States in 2015, the second-highest of any brand-name drug, according to the prescription tracker IMS Health. Crestor had been AstraZeneca’s best-selling drug, accounting for $5 billion of the company’s $23.6 billion in product sales that year.
But a generic version was approved in 2016, and sales of Crestor have dropped significantly since then. AstraZeneca’s revenue, which was reported on Thursday, was down 11 percent in the first half of the year, to $10.5 billion.
AstraZeneca also announced on Thursday that it would collaborate with Merck on developing Lynparza, a drug for various types of tumors, including breast, prostate and pancreatic cancers, and selumetinib, a drug that could be used on thyroid cancer.
Merck already produces its own drug that can be used in the treatment of lung cancer, but it suffered a recent setback in a trial for the drug’s use to treat head and neck cancer. A trial found that the drug, Keytruda, did not help patients of head and neck cancer survive any longer.
A separate AstraZeneca trial for a different lung cancer drug, Tagrisso, showed that it could help patients who had not already received treatment, the drug maker said on Thursday. Tagrisso is already used when initial treatments have not worked or have stopped working.