Sanofi nets valuable FDA voucher with approval for first oral regimen for neglected sleeping sickness

FDA priority review vouchers are valuable assets that drug companies use to expedite regulatory reviews of medicines with big commercial prospects. Thanks to an agency go-ahead in a rare tropical disease, Sanofi has nabbed such a certificate.

Sanofi’s fexinidazole has won an FDA green light to treat sleeping sickness, also known as African trypanosomiasis. It's a parasitic disease caused by the Trypanosoma brucei bug and transmitted by the tse-tse fly.

Alongside the approval, the FDA also doled out a tropical disease priority review voucher. Sanofi and its partner, the Drugs for Neglected Diseases initiative (DNDi), will equally share rights to the voucher, the French pharma said.

Without naming a specific product it intends to use the voucher on, a Sanofi spokesperson said the drug review coupon will allow the company to “accelerate access of other innovative medicines to patients.” 

Drugmakers typically use priority review vouchers on applications for drugs with high commercial expectations. Bristol Myers Squibb, for example, recently used such a voucher on Zeposia’s application in ulcerative colitis.

To shorten the FDA’s review timeline and therefore move up a drug’s launch by four months, biopharma companies have historically paid top dollar to get their hands on a priority review voucher. In January, Alexion—now on track to become part of AstraZeneca—bought one for $100 million from Rhythm.

Sleeping sickness isn’t a disease that affects the U.S. as the tse-tse fly is found only in sub-Saharan Africa. Thanks to control efforts, the World Health Organization recorded fewer than 2,000 cases between 2017 and 2019, the CDC said. It’s a curable disease but can be fatal if left untreated.

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The FDA go-ahead follows a positive opinion for fexinidazole from the European Medicines Agency in late 2018 under a pathway that allows drug reviewers to give opinions on meds that are intended for use outside the European Union.

Given that the FDA and the EMA are “two of some of the world’s most stringent regulatory authorities, we believe these regulatory nods will help with approvals in other parts of the world,” the Sanofi spokesperson told Fierce Pharma. The FDA nod “guarantees a quality product to treat all patients, in the context of the global fight against sleeping sickness,” the spokesperson added.

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While current treatments are effective, fexinidazole offers the first oral regimen, Sanofi said. Existing treatments may include intramuscular injections of antimicrobial drug pentamidine or intravenous infusions of eflornithine. The convenience of an oral therapy is important for sleeping sickness as the disease mostly affects people living in rural areas of sub-Saharan Arica, where medical logistics can be challenging.

Fexinidazole is now FDA-approved as a 10-day, once-daily treatment for both stages of sleeping sickness caused by the Trypanosoma brucei gambiense, which induces a slowly progressing disease mostly found in western and central Africa. The stages of disease are defined by whether or not the parasites have affected the central nervous system.