- AstraZeneca said Monday it will withdraw Imfinzi in advanced bladder cancer in the U.S., a year after a confirmatory trial showed the immunotherapy was no better than chemotherapy in helping patients live longer.
- The FDA's accelerated approval of Imfinzi in bladder cancer, granted in 2017, was based on tumor shrinkage and response data from an early-stage trial that tested the drug in different types of cancer. Such approvals are meant to be conditional, sustained only if drugmakers can confirm clinical benefits like survival rates over standard treatments, a standard Imfinzi failed.
- AstraZeneca's decision, which the British drugmaker made following discussions with the Food and Drug Administration, is one of several recent regulatory pullbacks by manufacturers of cancer immunotherapies.
Immunotherapies like Imfinzi, also known as checkpoint inhibitors, have changed how many cancers are treated, helping to extend lives by using the body's immune system to eliminate tumors. Since their first introduction 10 years ago, the drugs have become some of the top-selling products in the industry, with more than $25 billion in sales last year.
Much of that growth has come from drugmakers expanding which types of cancers the therapies can treat, while confirming promising early data in diseases like melanoma and lung cancer. In other tumor types, however, the progress has been more disappointing.
Bladder cancer was the first condition for which the FDA approved Imfinzi. The DANUBE trial was intended to confirm that Imfinzi's ability to shrink tumors would result in a survival benefit versus chemotherapy.
That didn't happen, however. Results, published last fall, showed that among patients whose tumor cells express a high level of a key protein which Imfinzi blocks, those given the drug survived a median of 14.4 months — statistically similar to the 12.1 months for patients who received chemotherapy.
A separate arm of the trial was designed to test whether patients given Imfinzi plus an experimental AstraZeneca drug called tremelimumab would do better. But the combination resulted in a median survival of only 15.1 months, again statistically similar to the chemotherapy group.
Imfinzi will remain on the U.S. market in two lung cancer settings. Unlike Merck & Co.'s top-selling Keytruda, however, Imfinzi has not won approval for first-line treatment of lung cancer, the largest market.
AstraZeneca isn't alone in its decision to withdraw an immunotherapy drug after disappointing data. Following the failure of a confirmatory trial, Bristol Myers Squibb in December withdrew its immunotherapy Opdivo for late-stage small cell lung cancer. And in January, Roche withdrew an application to the European Medicines Agency for use of Tecentriq in combination with chemotherapy as a first-line bladder cancer treatment.
Looking back further, in early 2020, Merck pulled a European application to expand Keytruda use to esophageal cancer.