Biogen shares soar as FDA approves Alzheimer's drug

Shares in Biogen closed nearly 40% higher after the biotech’s breakthrough Alzheimer’s drug received regulatory approval in the US.

The US Food and Drug Administration has approved aducanumab as an early treatment for the disease, despite mixed results from clinical trials. The FDA acknowledged the mixed results, but said the drug had been shown to reduce a protein called amyloid beta in the brains of people in the early stages of the disease. This, it said, was likely to benefit patients.

The announcement sent shares in the US firm soaring. At one point they jumped more than 50% before ending the session 38% higher. In pre-market trading on Tuesday, the shares were largely flat as at 1315 BST.

Aducanumab, which is branded Aduhelm, is the first new drug for Alzheimer’s to be approved in nearly 20 years. Biogen has priced the treatment, which purports to slow the progression of the disease, at $56,000 per year.

The FDA told Reuters that the accelerated approval pathway granted aducanumab was appropriate. Patrizia Cavazzoni, director of the FDA’s Center for Drug Evaluation and Research, said it allowed for "some residual uncertainty on the drug’s clinical benefits while making the drug available to patients rather than having to wait".

Biogen is required to conduct a confirmatory clinical trial but has "several years" to do so, Cavazzoni added.

Around 35 million people suffer from Alzheimer’s worldwide.