Sanofi is scrapping plans to get one of its more advanced experimental medicines approved for a certain kind of multiple sclerosis, following negative results from a clinical trial disclosed Monday.
The French pharmaceutical giant didn’t release any specific data, only that its drug, tolebrutinib, failed to meet the main goal of a late-stage trial titled PERSEUS. The study enrolled 767 participants with a rarer form of MS known as primary progressive, and looked at whether tolebrutinib was any better at delaying the disabilities that typically worsen over the course of the disease.
Based on these results, Sanofi will not attempt to get the drug approved in this setting. The company is also evaluating if it needs to take an impairment charge related to tolebrutinib’s intangible value, given that the drug was the centerpiece of a $3.7 billion buyout. Sanofi intends to provide an update on this evaluation in January — though it noted that, either way, the outcome won’t impact net income or earnings per share. Its 2025 financial guidance remains unchanged.
“We are disappointed by today’s results; however, we do believe [they] will improve our understanding of the underlying disease biology of multiple sclerosis,” said Houman Ashrafian, head of Sanofi’s research and development, in a statement.
Separately, Sanofi on Monday revealed that an approval verdict for tolebrutinib as a treatment for “non-relapsing secondary progressive” MS will likely come later than expected.
The Food and Drug Administration had previously aimed to make a decision by Sept. 28, but pushed that deadline back by three months after Sanofi made a “major amendment” to its application. Now, the company suspects recent discussions with the FDA indicate a ruling won’t come by the revised date of Dec. 28. Sanofi anticipates more guidance from the agency sometime in the first three months of next year.
The company said it “strongly believes” in tolebrutinib’s risk-benefit profile. In response to an FDA request, it has submitted an “expanded access protocol” so eligible patients with non-relapsing secondary progressive MS can get ahold of the drug.
“The fact that the FDA has requested an extended access program suggests the agency is comfortable with the risk/benefit for now,” wrote analysts at the investment bank Jefferies, in a note to clients.
“The market may well write the asset off, but that seems a bit premature,” the analysts added. “We wonder if more share price pressure will mean more pressure on management.”
Tolebrutinib comes as a tablet, and is part of a class of drugs designed to inhibit “Bruton’s tyrosine kinase,” an immune system-regulating enzyme that plays a key role in the development of B cells.
Those cells make antibodies that alert the body to potential threats. Research suggests a root cause of MS is antibodies mistakenly attacking the protective “myelin sheaths” that cloak nerve fibers.
Sanofi already has one BTK-blocking drug, Wayrilz, on the market for a different autoimmune condition. So does Novartis. BTK inhibitors like Imbruvica, Calquence and Brukinsa are used to treat certain blood cancers as well. The class as a whole carries safety concerns, namely the potential for liver injury, which in recent years led the FDA to issue partial clinical holds on tolebrutinib and similar drugs from Roche, Merck KGaA and InnoCare Pharma.
This fall, that Roche drug, fenebrutinib, succeeded in two large MS trials. One recruited primary progressive patients, while the other focused on the far more common “relapsing” form of the disease. Jefferies analysts described those readouts as a “positive surprise,” though they also questioned whether Roche had collected enough supportive evidence to file for approval.
