Generation Bio shares halved as hemophilia gene therapy hunt goes back to square one

Generation Bio’s shares were briefly halted Tuesday morning on the release of mouse data that complicated its search for a viable target for hemophilia A to take into the clinic.

The biotech, which joined the public markets with an IPO that had proceeds of $230 million in June 2020, announced in a Securities and Exchange Commission filing that data from early preclinical mouse studies did not translate into nonhuman primates.

This one is in the weeds, but Generation's previous research in mouse models found that their candidate demonstrated peak mean human factor VIII expression of 205% of normal. Factor VIII is an essential blood-clotting protein and a key biomarker for patients with hemophilia. New gene therapies are trying to correct deficiency of that protein to prevent bleeding episodes.  

However, once the candidate was administered to nonhuman primates, that peak mean human factor VIII expression dropped to just 2%. That result is now sending Generation back to the drawing board to come up with a new candidate that might work in humans.

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After trading on Generation’s shares resumed, the price plummeted more than 55% to $6.22, compared to a prior close of $13.60.

Generation had promised to pick its clinical candidates over the course of 2020, with IND-enabling studies planned for this year. Applications to the FDA for human testing were expected in 2022.

That timeline will be pushed back—way back. The company now plans to provide updates to its pipeline program sometime in 2022 and timing for IND submissions will come “in the future.”

This is a cautionary tale for the hot IPO arena that has seen biotechs leap to the public markets based purely on preclinical data.

Nevertheless, Chief Scientific Officer Matthew Stanton, Ph.D., said the company has learned plenty about its platform in collecting the animal study data, specifically around manufacturing capabilities and production processes.

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“We are working to translate the improved potency and decreased variability that we have observed in mice to [nonhuman primates],” Stanton said.

Back in January, Generation said its candidate had been successfully delivered to the liver of nonhuman primates. At the time, Stanton referred to data on the demonstration of translation from mice to nonhuman primates as “important proof points for our platform.”

Generation is aiming to “exceed the limits of conventional gene therapies,” CEO Geoff McDonough, M.D., said in a Tuesday statement. The company’s gene therapy technology is based on a non-viral genetic medicine platform.