FDA, Regulatory

FDA slaps a clinical hold on messenger RNA program for rare genetic disease

Translate Bio’s plans to put a second messenger RNA drug in the clinic in the first half of 2019 has just ground to a halt in front of a sudden regulatory red light.

Ron Renaud

The biotech $TBIO, which went public in the class of 2018, announced this morning that the FDA has slapped a clinical hold on its IND for MRT5201. The IV drug is designed to address rare cases of ornithine transcarbamylase (OTC) deficiency, an X-linked genetic disease.

All we know right now is that the FDA has conveyed verbally that regulators have “additional clinical and nonclinical questions” for the biotech. The agency itself never discloses its position on these cases publicly. 

Shares in the biotech was down 7.5% mid-day Tuesday — not a dreadful outcome.

Leerink’s Geoffrey Porges talked with the management crew, who gave the analyst the impression that this hold was a lot like the temporary one they got for their lead effort. But whatever inspired it, the FDA’s decision has no impact on the top drug for cystic fibrosis. He notes:

At this stage it is impossible to tell whether this clinical hold amounts to a short- or long-term development delay for MRT5201, but regardless it does not seem to have any spillover implications for the company’s principal value driver, which is their lead development program MRT5005 in CF. The company assured us that enrollment in the SAD phase of the MRT5005 program is continuing without change, and the company expects to announce the first CF patient enrollment into the MAD phase of this trial shortly.

Messenger RNA, a field led by a slate of biotechs including Moderna and BioNTech, works by delivering code to a cell to instruct it to make a drug. In this case the coding directs liver cells to make normal OTC enzyme. That’s a concept that is easy to understand and devilishly difficult to accomplish. 

Translate, which is helmed by Ron Renaud, says it is awaiting formal communications from the FDA and then will tackle whatever issues are on the table. The company — which raised $122 million from its IPO and has a market cap of $250 million — has a Phase I/II trial underway on cystic fibrosis, according to its web site.


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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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