Sanofi’s investigational Bruton’s tyrosine kinase (BTK) inhibitor tolebrutinib has been granted breakthrough therapy designation by the US Food and Drug Administration (FDA) as a treatment for adults with non-relapsing secondary progressive multiple sclerosis (nrSPMS).
A breakthrough therapy designation is given by the FDA to accelerate the development and regulatory review of potential new medicines that target serious conditions.
The regulator’s decision on tolebrutinib was supported by positive results from the late-stage HERCULES study, in which the drug delayed the time to onset of six-month confirmed disability progression by 31% compared to placebo.
The number of patients in the trial who experienced confirmed disability improvement also increased in the tolebrutinib arm, at 10% versus 5% in the placebo cohort.
Affecting approximately 2.9 million people worldwide, multiple sclerosis (MS) occurs when the immune system attacks the protective myelin sheath that covers the nerves and disrupts communication between the brain and the rest of the body.
Relapsing MS, characterised by attacks of worsening neurologic function followed by partial or complete recovery periods, accounts for about 85% of initial diagnoses, while nrSPMS, which refers to patients who have stopped experiencing relapses but continue to accumulate disability, is much less common.
Taken orally, Sanofi’s tolebrutinib is designed to block the action of the BTK enzyme, which is essential for the survival and activation of a type of white blood cell thought to be involved in the inflammation caused by MS.
The drug is being assessed in various forms of the disease, including primary progressive MS, and is now the first and only brain-penetrant BTK inhibitor in MS to be designated breakthrough therapy by the FDA.
Erik Wallström, global head of neurology development at Sanofi, said: “This breakthrough therapy designation demonstrates the potential for tolebrutinib to delay disability progression, a critical unmet need for people living with MS.
“We look forward to working with the FDA during the regulatory review of this first of its kind medicine in nrSPMS where there are currently no approved treatments available.”
Regulatory submissions of tolebrutinib are currently being finalised for the US and prepared for the EU, Sanofi said.