Sanofi’s long and winding path to get its investigational multiple sclerosis drug over the regulatory finish line has taken another turn with the FDA's move to delay its approval decision on the candidate by three months.
BTK inhibitor tolebrutinib—which was acquired in Sanofi’s $3.7 billion takeover of Principia Biopharma in 2021—had been on course for an FDA decision by Sept. 28 after Sanofi nabbed a priority review earlier this year. The company is seeking approval for the drug to treat non-relapsing secondary progressive multiple sclerosis (nrSPMS) and to slow disability accumulation independent of relapse activity in adult patients.
But the FDA now wants three more months to review the drug’s case after the French Big Pharma sent the U.S. agency “additional analyses during the review,” something that constituted a major amendment to its original NDA. The new decision target date is Dec. 28.
In a brief statement, Sanofi said it is “confident in the potential positive impact tolebrutinib can provide and will continue to collaborate closely with the FDA during the review period.”
The pharma has long touted the med as a potential blockbuster, but this is another bump in the road for the drug. A year ago, the med fell short in two of three phase 3 trials, denting its prospects and ultimately reducing its therapeutic scope.
Tolebrutinib had been evaluated across two forms of the chronic neurological disorder. The Hercules study involved patients with nrSPMS, while two identical phase 3 studies, dubbed Gemini 1 and 2, were focused on relapsing MS.
The Hercules study was a success, with tolebrutinib hitting the primary endpoint of delaying progression of disability compared to placebo.
But, in the Gemini trials, tolebrutinib failed on the primary endpoint of besting Sanofi’s own approved MS drug Aubagio when it came to reducing relapses over up to 36 months. Trying to find the positives, the company said an analysis of six-month data from those trials showed there had been a “considerable delay” in the onset of disability.
Sanofi then decided to specifically focus on the indication of nrSPMS where it saw success in the Hercules trial.
That was not the first time tolebrutinib had faced challenges in the clinic. The FDA placed a partial hold on further enrollment on all three of those trials three years ago over what the company described at the time as “a limited number of cases of drug-induced liver injury that have been identified with tolebrutinib exposure.”
Sanofi has, however, had better news on the BTK front of late, having grabbed an FDA approval just last month for Wayrilz in immune thrombocytopenia, a drug that also came out of its Principia buyout.