Sanofi’s most advanced multiple sclerosis (MS) drug candidate has missed the main goal of two late-stage trials to treat relapsing forms of the disease, dimming the prospects for a widely-pursued class of drugs.
The French drugmaker said on Monday that two Phase III trials showed that its experimental daily pill tolebrutinib was not better than its established MS drug Aubagio in reducing relapse rates in a highly common form of MS characterised by isolated flare-ups followed by temporary improvements.
In a mitigation of the setback for Sanofi, the company said a separate third late-stage trial showed that tolebrutinib met the main goal to treat a progressive – or steadily worsening – form of MS, which is less common and which currently cannot be treated.
In that trial, the Sanofi drug candidate slowed disability progression when compared with placebo, an ineffective dummy drug.
“Tolebrutinib represents an unprecedented breakthrough as a potential first-in-disease treatment option with clinically meaningful benefit in disability accumulation,” said Houman Ashrafian, head of research & development.
The company added it would discuss those results with regulators, aiming to file for approval by the end of 2024.
Sanofi is pursuing several opportunities in MS, a debilitating nerve disease, to offset revenue losses after the recent end of the Aubagio pill’s patent protection, part of a push to become a powerhouse in anti-inflammatory drugs.
CEO Paul Hudson has been trying to regain investor confidence in the pharma pipeline since he unexpectedly abandoned 2025 margin targets last October to boost drug development spending.
Its shares have bounced back somewhat over recent months on the strength of drug launches including Beyfortus to protect infants against a common respiratory infection.
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Tolebrutinib, from the $3.7 billion takeover of Principia Biopharma in 2020, belongs to a class of compounds known as Bruton’s tyrosine kinase (BTK) inhibitors, which has also attracted drug majors Novartis, Roche and Merck KGaA.
They are designed to selectively block the harmful autoimmune reaction behind MS for a more targeted approach than standard immunosuppressant drugs.
Investors, however, have been kept on edge over revenue prospects because of a possible link to liver damage and uncertain efficacy.
In 2022, concerns over liver damage led to a halt in the enrolment of new patients in three of Sanofi’s tolebrutinib studies that were still recruiting volunteers at the time.
On Monday, Sanofi only said liver safety was consistent with previous studies, with more data to be disclosed on Sept. 20.
Merck KGaA’s BTK inhibitor, too, had been under scrutiny for liver safety.
That drug last December missed its efficacy goal in MS trials, a major blow to the German company’s growth ambitions.
Roche subsidiary Genentech is still in the race, but safety concerns about its BTK inhibitor have also emerged last November.
Rival Novartis has said that its BTK drug candidate had shown no signs of liver damage.
Sanofi on Monday only provided a brief summary of the two relapsing-MS trials called GEMINI I & II and of the HERCULES trial on a form of progressive MS. It said details would be presented at the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) conference in Copenhagen on Sept. 20.
Another Phase III study known as PERSEUS in another progressive form of MS is still ongoing with results expected in 2025, Sanofi added.
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