Swift setback: A preclinical success in hep B is followed by safety woes

Dr. Marc Pellegrini

A few weeks ago, TetraLogic Pharmaceuticals ($TLOG) touted a preclinical program demonstrating that its drug birinapant could play a major role in swiftly erasing hepatitis B. Soon after, the Malvern, PA-based biotech announced that it had struck a deal to put the blood cancer drug into a combination study with Merck's ($MRK) PD-1 star Keytruda, setting the stage for a plan to raise money through the sale of stock.

And then a safety scare that followed just days later underscored the risk involved in heralding the success of animal studies.

Scientists from Melbourne's Walter and Eliza Hall Institute caused a stir in late April when they noted that birinapant in combination with an antiviral cleared hepatitis B in the mouse models it used in its animal study. A number of media outlets highlighted the early evidence of a cure.

"Birinapant enabled the destruction of hepatitis B-infected liver cells while leaving normal cells unharmed," said Marc Pellegrini. "Excitingly, when birinapant was administered in combination with current antiviral drug entecavir, the infection was cleared twice as fast compared with birinapant alone. We are hopeful these promising results will be as successful in human clinical trials, which are currently underway in Melbourne, Perth and Adelaide."

The human trials, though, had to be stopped days ago when investigators noted cases of cranial nerve palsies among the patients in the first cohort of patients enrolled in the Phase I study. The biotech's brief statement on the snafu said that the study halt was temporary. Investors, though, weren't happy, sending the company's stock down 30% and throwing a monkey wrench in the company's plan to raise $25 million.

Preclinical stage programs suffer from an extraordinarily high failure rate. And TetraLogic's travails right now, even if it gets back on track, help showcase just how big the risk can be.  

- here's the release on the animal study
- here's the FierceBiotech story on the safety concerns

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