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its two lead candidates, for urea cycle disorders and phenylketonuria, will require smaller trials that take less cash to complete than studies in more common diseases. Gutierrez-Ramos says that Synlogic can get a signal that its drug is working in PKU, for instance, if it’s tested in a sample size of 30 to 40 patients. In IBD, that would take a few hundred, he says.
But first Synlogic has to reach those studies, a more difficult challenge than it would be with yet another small molecule or antibody drug. Synlogic has to convince regulators that it’s safe for people to ingest genetically engineered bacteria before it can begin testing them in people. “Clearly [these drugs] will have a different type of regulatory scrutiny—and they should,” Gutierrez-Ramos says.
Synlogic has already taken a few steps to address potential problems. For instance, it is using probiotic bacteria that are already part of the human microbiome—in other words, bacteria that our bodies already recognize and theoretically won’t trigger unintended consequences. Synlogic is wiring those bacteria with genetic circuits that come either from human genes or those of other bacteria in the microbiome. It’ll also use bacteria that survive for a short time, rather than colonize the gut.
“This is the armamentarium that we will take in [to discussions with regulators],” Gutierrez-Ramos says, noting that the outcome of those meetings will be a “very important milestone” for the company.
Should Synlogic get the green light to start human testing, would success in these initial studies propel the company towards an IPO? Flash back to just a year ago and a round like this, which includes a “crossover” investor, Deerfield Management, was all but a guarantee that an IPO was on the way. But biotech has tumbled, and the IPO market has become shaky ever since. Synlogic is taking its time.
“I don’t want us to get distracted by things we can’t control,” says Gutierrez Ramos, speaking of the public market for biotechs. “If we get a significant signal [that our drugs work in humans] as I hope we will, then we’ll see what the market is and what the next step is.”