Amid the prosecution’s probe into Kolon Life Science’s osteoarthritis gene therapy Invossa-K, it is drawing attention whether the company could win U.S. approval to resume a trial on the drug.

Industry watchers are watching whether the Food and Drug Administration (FDA) will allow the drug to contain kidney-derived cells (GP2-293 cells) that can potentially cause cancer.

A former long-time FDA reviewer told Korea Biomedical Review that the FDA would not reject the trial resumption application just because the drug contained 293 cells. “If the company conducted radiation exposure as recommended, and if there is no chance of causing cancer, the authorities will not take issues with carcinogenicity risk,” he said.

As the company revealed that the second fluid of Invossa contained 293 cells, not cartilage-derived cells, the company’s global phase-3 trial on the drug received “Clinical Hold” from the FDA in May. The FDA demanded the company submit documents, including the analysis of ingredients’ characteristics and a report on why ingredients were changed, to resume the trial.

On Sept. 29, the FDA demanded additional data after reviewing the submitted documents. The critical data is from a test to check whether retroviruses are generated after introducing the Env gene into the second fluid before and after irradiation. The test takes about three to four months.

“The FDA is probably most concerned about the possibility of generation of retroviruses when Invossa is injected into the knee joint cavity,” the former FDA reviewer said. “The result of this test is the most important. If there is no virus budding, the trial will be resumed.”

The issue of 293 cells’ potential of causing cancer is plausible only when there is no irradiation, he went on to say. Because the company had irradiation and Invossa is injected into the knee joint cavity where no blood is found, 293 cells’ possibility of causing cancer is nearly zero, he added.

He also criticized the Ministry of Food and Drug Safety for revoking the Invossa license recently. Canceling the permit just because the drug’s ingredient was different from the submitted data was not a judgment based on science.

Recently, the U.S. regulator found that Novartis fabricated pre-clinical data for Zolgensma. Still, the FDA did not revoke its license saying there was no problem in the drug’s efficacy and safety, he noted, adding that the FDA was investigating the case to hold the company accountable.

“In the U.S., the regulator does not cancel a permit even if related data is wrong, as long as it has nothing to do with the safety and efficacy of the drug,” he said.

The former FDA reviewer emphasized that clinical trial results show the efficacy and safety of a drug. While many patients received Invossa treatment, no case suffered a side effect because of the changed ingredient of the drug, he added.

“The food and drug safety ministry’s revocation of the Invossa license, based on the assumption that patients could be in danger, was a non-scientific decision,” he said.

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