US drug agency will not approve alemtuzumab

French pharmaceutical Sanofi has run into trouble after the US Food and Drug Administration (FDA) rejected its multiple sclerosis drug Lemtrada (alemtuzumab). The agency said that its rejection of alemtuzumab was the result of poor Phase III clinical trial design and side effects that outweigh the potential benefits.

When Sanofi bought Genzyme for more than $20 billion (£12 billion) in February 2011, additional milestone payments were agreed, depending on the success of alemtuzumab. The monoclonal antibody was approved to treat multiple sclerosis in the EU in September 2013, leading to expectations that the FDA would follow suit in the US.

Without the US market, Lemtrada is very unlikely to meet sales targets, and consequently Sanofi’s share price fell by 1.1%. Furthermore, one US law firm is launching a class action on behalf of investors, claiming the French company made misleading statements about the prospects for alemtuzumab.

In a press release, a spokesperson for Genzyme stated that they strongly disagree with the conclusions and plan to appeal against the FDA’s decision.

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