Roche’s fenebrutinib this week scored a mid-stage win in relapsing multiple sclerosis, while Sanofi’s tolebrutinib met the primary endpoint in a Phase III trial for progressive MS but flopped in two late-stage relapsing MS studies.
It was a big news week for multiple sclerosis clinical trial readouts involving oral BTK inhibitors, which leverage their small molecular structure to cross the blood-brain barrier. Roche was the outright winner while Sanofi announced mixed results.
Sanofi’s tolebrutinib on Monday missed the primary efficacy endpoints in two Phase III studies, failing to significantly reduce annualized relapse rate (ARR) in patients with relapsing MS (RMS), while succeeding in a third late-stage trial showing that the BTK inhibitor significantly delayed disability progression in patients with a less common form of progressive MS.
Still, according to GlobalData, tolebrutinib “stands out as being particularly promising” and is expected to generate sales of approximately $2.6 billion in 2030 across seven major markets—the U.S., France, Germany, Italy, Spain, U.K. and Japan. The data analytics firm predicted worldwide sales of fenebrutinib will only reach $810 million that same year.
Jefferies analysts described positivity around tolebrutinib, saying in a note to investors that despite the “mixed news,” Sanofi’s drug “now appears a largely de-risked perhaps $1–2 billion opportunity.”
Meanwhile, just two days after Sanofi’s announcement, Roche’s fenebrutinib scored a mid-stage win in RMS, demonstrating near-total elimination of disease activity. GlobalData said the BTK inhibitor “shines” with 96% of patients treated free of relapses at one year, with data from three ongoing Phase III trials expected by the end of next year.
According to Spherix Global Insights, orally administered BTK inhibitors are “already established in oncology” with U.S. neurologists “eagerly” awaiting the drug class for MS. However, the market research firm contends that setbacks involving safety have created an environment of uncertainty.
Liver Safety and Secondary Endpoints in Focus
While the overall sentiment for BTK inhibitors for MS is positive, the safety profile of these treatments remains a point of concern. Sanofi’s Phase III tolebrutinib studies were placed on partial clinical hold by the FDA in June 2022 after researchers found cases of drug-induced liver injury in some patients, while the regulator put Roche’s fenebrutinib under a partial clinical hold in December 2023 after two patients experienced elevated hepatic transaminase and bilirubin levels indicative of liver injury.
According to Jefferies analysts, liver safety “will be a key focus” at the Sept. 20 presentations of Sanofi’s HERCULES and GEMINI 1 and 2 full results at the 40th Congress of European Committee for Treatment and Research in Multiple Sclerosis in Copenhagen, Denmark.
Shiv Saidha, professor of neurology at Johns Hopkins University, said on a Jefferies call Thursday that another important aspect of these data will be the benefit across secondary endpoints, noting the failure last year of Merck KGaA’s BTK inhibitor evobrutinib to show benefit on these measures in MS before the German pharma decided in March 2024 to terminate its development.
Although Sanofi’s Phase III GEMINI 1 and 2 trials did not demonstrate a reduction in ARR, GlobalData observed that pooled data from secondary endpoints suggested a significant delay in the onset of confirmed disability worsening, aligning with the positive confirmed disability progression findings from the late-stage HERCULES study, and “providing a measure of support for tolebrutinib’s potential efficacy.”
Nevertheless, there appears to be a bit of a confidence problem in the wider drug class, Jefferies analysts noted. “Investor expectations have likely been notably lower after competitor Merck KGaA’s evobrutinib RMS failure.” So the question remains: Can orally administered BTK inhibitors ultimately succeed in MS like they have in oncology?
