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FDA puts Translate Bio’s rare disease mRNA drug on hold

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The last time Translate Bio ran into a clinical hold, it resolved the issue in four months

The FDA has placed a clinical hold on the IND for Translate Bio’s mRNA treatment for ornithine transcarbamylase (OTC) deficiency, a genetic disease that causes too much ammonia to build up in the blood. The hold comes just nine months after the agency lifted a clinical hold on a different program, its lead asset, in development to treat cystic fibrosis.

The agency told Translate Bio verbally that it placed the hold because it had “additional clinical and nonclinical questions” after reviewing the IND for the candidate, MRT5201. The company submitted the application in December and is now is now waiting for an FDA letter with more details so it can work on the issues and get the treatment into the clinic.

OTC deficiency is an X-linked disease in which high ammonia levels in the blood affects the nervous system. Symptoms vary between patients and may include lack of energy and appetite, poorly controlled breathing rate and body temperature, unusual body movements, seizures or coma. Current treatments focus on keeping ammonia levels down, using a combination of dietary restriction and drugs that help remove nitrogen, a component of ammonia, from the body.

MRT5201 treats OTC enzyme deficiency by delivering mRNA that codes for the normal OTC enzyme into the liver, enabling liver cells to produce the enzyme.

The last time Translate Bio ran into a clinical hold, it resolved the issue in four months. After placing the hold on MRT5005, the cystic fibrosis program, in December 2017, the FDA then asked for more information about chemistry, manufacturing and controls related to certain materials, processes and testing used during the manufacturing of MRT5005. Translate Bio didn’t have to run additional studies to gather that information.

MRT5005 could improve upon existing CF drugs as it has the potential to treat all patients with the disease, regardless of the underlying mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Vertex’s approved CF drugs Kalydeco, Orkambi and Symdeko target specific mutations are only suitable for use in around 30,000 of the 70,000 patients with CF worldwide.