Sanofi’s MS Drug Takes Double Hit With FDA Delay, Trial Failure

Sanofi’s experimental multiple sclerosis drug got hit with two setbacks on Monday: a regulatory delay in the US as well as a failure in a late-stage clinical trial.

US-listed shares of Sanofi dropped 4.9% in overnight trading.

The US Food and Drug Administration decision on the medicine, called tolebrutinib, to treat an advanced form of multiple sclerosis will likely be delayed, with further guidance from the regulator at the end of the first quarter, the French drugmaker said.

In another blow, Sanofi said tolebrutinib did not delay the progression of disability in patients with primary progressive multiple sclerosis in a late-stage trial. The drugmaker will not purse a regulatory approval for this indication, which represents about 10% of the overall patient population.

Sanofi has faced hurdles developing the medicine, with trials pointing to a risk of liver injury. The company did not give reasons for the expected FDA wait. The review was already delayed in September by three months.