AstraZeneca plc (NASDAQ:AZN) announced Monday a setback related to its key immuno-oncology therapy Imfinzi.

What Happened: The U.K. drugmaker said it is voluntarily withdrawing Imfinzi from the U.S. market as a treatment option for previously treated adult patients with locally advanced or metastatic bladder cancer.

The company said the decision has been made in consultation with the FDA.

Incidentally, it was the first indication for which Imfinzi was approved in the U.S.

Imfinzi was granted accelerated approval for the indication in the U.S. in May 2017 on the basis of positive results from a Phase 1/2 trial dubbed Study 1108. The approval issued was contingent on results from the Phase 3 DANUBE study in a first-line metastatic bladder cancer setting.

With the DANUBE study flunking the study goals in 2020, AstraZeneca opted to pull the drug out of the market for the indication, aligning with the FDA guidance for evaluating indications with accelerated approvals that did not meet post-marketing requirements.

AstraZeneca clarified that the withdrawal does not impact the indication outside the U.S. or other approved Imfinzi indications within or outside the U.S.

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Why It's Important: Apart from bladder cancer, Imfinzi has been approved in the U.S. for treating stage 3 non-small cell lung cancer that cannot be surgically removed and for extensive-stage small cell lung cancer.

Imfinzi is also being evaluated as a monotherapy and in combinations for several indications, including non-small cell lung cancer, small cell lung cancer, bladder cancer, liver cancer, biliary tract cancer and esophageal cancer.

In fiscal year 2020, Imfinzi fetched the company revenues of $2.042 million, or roughly 8% of the total.

AstraZeneca said it has notified health care providers of the update. It also recommended patients who are already on Imfinzi for metastatic bladder cancer to consult with their health care provider regarding ongoing care.

AZN Price Action: AstraZeneca shares shrugged off the adverse development and were 0.28% higher at $50.73 at last check Monday.

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