FDA Halts Sanofi’s $3.7B Multiple Sclerosis Investment

The FDA has placed 5 Phase 3 studies of Sanofi’s tolebrutinib in multiple sclerosis (MS) and myasthenia gravis on partial clinical hold, due to reports of drug-induced liver injury. The decision raised doubts about Sanofi’s 2020 purchase of California-based Principia Biopharma, in an effort to rejuvenate Sanofi’s R&D portfolio. 

As result, new enrollment in the United States is paused, and participants who have been in the trial for fewer than 60 days shall suspend the study drug, but participants who clocked at least 60 days in the trial should continue treatment. The concerned studies are GEMINI 1 & 2, PERSEUS, HERCULES, and URSA.

Tolebrutinib is a brain-penetrating Bruton’s tyrosine kinase (BTK) inhibitor that achieves cerebrospinal fluid concentrations needed for targeting B lymphocytes and microglial cells.

Related article: US Court Rules Novartis Blockbuster Multiple Sclerosis Drug’s Patent Invalid 

Trials Outside US to Continue With Revised Protocol

Sanofi said that it spoke with the FDA in May 2022 about these liver injury cases, subsequently, patient enrollment criteria were updated to exclude participants with preexisting risk factors for liver dysfunction. 

Outside the US, trials are already proceeding with the revised trial protocols, Sanofi said it boosted its safety surveillance in all countries and is actively evaluating robustness of these new measures. 

The FDA only suspended trials for participants below 60-days; many patients are expected to carry on with the study since the initial 2019 recruitment. Currently, there are more than 2,000 combined studies participants  who are being treated with tolebrutinib for more than 3 years.

Any setbacks at this stage could hinder Sanofi’s trials to emerge next year, companies such as Merck and Roche also have similar ongoing trials for multiple sclerosis, with Merck expecting trial results next year as well. 

Since 2011, Sanofi has rapidly emerged as a leader in multiple sclerosis treatment. In 2020, Sanofi recorded $5.8 billion in sales from its MS business, close to 90% of which came from Aubagio alone. With the BTK inhibitor in its pocket, Sanofi is expected to generate international sales of $2 billion, provided it succeeds in the Phase 3 trial.

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Author

Fujie Tham