FDA fails in delayed superposition trial Sanofi (SNY.US) multiple sclerosis drug is doubly attacked

The Zhitong Finance App learned that the experimental multiple sclerosis drug from Sanofi (SNY.US) experienced a double setback on Monday: regulatory delays in the US occurred, and at the same time, a late-stage clinical trial failed.

The French pharmaceutical company said the US Food and Drug Administration (FDA) approval decision for its drug tolebrutinib to treat advanced multiple sclerosis may be delayed, and regulators will provide further guidance at the end of the first quarter. Sanofi shares plummeted 6.4% in early trading in Paris, the biggest drop in more than three months.

As of press release, the US stock was down 1.97% in the premarket.

To make matters worse, Sanofi said that in a late-stage trial for primary progressive multiple sclerosis, tolebrutinib failed to delay the progression of patients' disability.

Analyst John Murphy said the double blow could threaten the drug's annual sales peak of up to $1.7 billion. Sanofi has faced obstacles in developing this drug, and tests have shown that it poses a risk of liver damage. The company did not explain the reason for the FDA's anticipated delay. The review was delayed for three months in September of this year.

Murphy and her colleague Milla Bankovskaya wrote in a report: “The reason for the delay in US approval is unclear and may revolve around the liver safety of tolebrutinib, but we ultimately expect the drug will still be approved.”

Jefferies analyst Michael Leuchten believes it's too early to deny the drug. He notes that tolebrutinib targets unmet medical needs, and that Sanofi has submitted data for an expanded accessibility program — which means that patients may receive the drug due to no other alternatives while awaiting approval — “which indicates that the FDA currently approves its risk-benefit ratio.”

Brain and spinal cord

The company is conducting impairment tests on the value of assets associated with tolebrutinib and will provide an update in January. Sanofi said the results will not affect its main profit indicators, and there are no changes to the 2025 performance guidelines.

Including Monday's drop, Sanofi's stock price has fallen 15% so far this year, and its performance is lower than that of its peers.

Multiple sclerosis is a complex disorder that affects the brain and spinal cord, causing symptoms such as muscle cramps, numbness, and fatigue. There are several types of this disease, the most common of which are periods of sudden deterioration alternating with periods of recovery. In primary progressive multiple sclerosis, symptoms continue to worsen, and there is no recovery period. Sanofi said it will no longer seek regulatory approval for this indication, which accounts for about 10% of the total number of patients.

Another type is secondary progressive multiple sclerosis, which is characterized by a steady increase in disability, and it is this type that Sanofi has declared to the FDA. Sanofi obtained tolebrutinib when it acquired American biotech company Principia BioPharma in 2020.