Sanofi snags speedy review for Principia BTK drug, Pompe program

Sanofi’s rare disease programs are racking up speedy review tags. After scoring breakthrough and fast-track status from the FDA, the French pharma’s Pompe disease treatment grabbed a priority review tag, setting it up for an FDA decision next spring. The agency also fast-tracked rilzabrutinib, a BTK inhibitor Sanofi picked up in its $3.7 billion buyout of its partner Principia Biopharma.

People with Pompe disease have mutations in the GAA gene, which stops them from making enough of an enzyme of the same name. With too little of this enzyme, their calls can’t break down a complex sugar called glycogen into the simple sugar glucose. The glycogen buildup then causes tissue damage, particularly in the muscles, including heart muscle and the muscles that support breathing.

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Sanofi’s Pompe program, avalglucosidase alfa, is an enzyme replacement therapy designed to boost the delivery of GAA enzyme to muscle cells. Its FDA submission is based on a phase 2 trial in patients diagnosed as infants and a phase 3 study comparing the treatment to the standard of care, alglucosidase alfa, in patients with late-onset disease.

The FDA expects to make a decision on avalglucosidase alfa by May 18, 2021. The European Medicines Agency started reviewing it in October. Sanofi hopes it will become a new standard of care for people with Pompe disease.

“The hallmarks of Pompe disease are the relentless and debilitating deterioration of the muscles, which causes decreased respiratory function and mobility,” said Karin Knobe, head of development for rare diseases and rare blood disorders at Sanofi, in a statement. “Avalglucosidase alfa is specifically designed to deliver more GAA enzyme into the lysosomes of the muscle cells. We have been greatly encouraged by positive clinical trial results in patients with late-onset and infantile-onset Pompe disease.

As for rilzabrutinib, Principia had been developing the BTK inhibitor for several diseases, including autoimmune skin disorder pemphigus, blood disorder immune thrombocytopenia (ITP), and IgG4-related disease, a rheumatologic condition. The fast-track tag is for its development in ITP, a rare disease in which the immune system attacks and destroys platelets, the component of blood responsible for clotting.

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There is no cure for ITP; treatment focuses on preventing bleeding and stabilizing or improving platelet counts. A big challenge for patients with ITP is finding a treatment that works without side effects, according to the National Organization for Rare Disease. These can include high blood pressure, blood clots, diarrhea and abnormal liver tests.