Kolon Life Science announced on April 10 that it would verify the safety of Invossa, the world's first osteoarthritis gene therapy treatment, by keeping track of the 3,000 patients who were administered with the drug for 10 years.
Questions were raised about the safety of Invossa after the company announced on April 1 that it has confirmed the main cells used in the gene therapy treatment have been confirmed to be different from the ones approved for marketing in Korea.
The company will announce the results of its inspection into the matter on April 15. The most controversial part is that the transfected cells, which are the key components of the drug, are not cartilage-derived cells but are kidney-derived cells and that their source is tumorigenic HEK293.
The presence of tumorigenicity indicates the possibility of the cells developing into cancer cells. Some argue that development and validation of cells that are tumorigenic (kidney cells) before transformation should be different from that for cells that are not tumorigenic (chondrocytes) before transformation.
In response, Kim Su-jung, head of the Kolon Life Science Research Center, said, "All cells develop tumorigenicity at the moment of transformation. Tumorigenicity of the original cells and that of cells after transformation are not related." According to Kim, tumorigenicity develops regardless of the type of the original cell.
She also added, "Kolon is fully aware of the risk of tumorigenicity and has secured safety by emitting radiation higher than the standard." She said that the company irradiated radiation to two solutions of Invossa, and after rapid freezing, partially thawed them and cultured them for 44 days. Only after confirming that all the cells have died, the company thawed the remaining cells and injected them into two solutions to secure full safety.
Kolon also rejected the argument that it is necessary to carry out clinical trials all over again since the requirements for performing clinical trials have changed. The company argues that as the cells were changed from the beginning of the clinical trials, a change of composition is enough. Yoo Soo-hyun, executive director of the company’s bio division, said, "As it has already been proven safe from the U.S. Food and Drug Administration (FDA) and the Korean Ministry of Food and Drug Safety (MFDS), we will not be required to repeat the clinical trial, but we will cooperate with investigations.”
“Some say that we delayed the report of composition change, but wereported to the Drug Ministry first, even though it was not obligatory,and decided to discontinue sales voluntarily,” he added
As the controversy over the safety of Invossa continues, Kolon decided to conduct 10-year follow-up, with assistance from the Drug Ministry, on all 3,000 patients who were administered with Invossa, in addition to the patients who participated in the clinical trials. In the medical field, the period of time in which cancer has been remedied is five years, meaning that if the company can show that there has been no abnormality for more than twice the period, it can prove the safety of Invossa.
Kolon Tissue Gene, which has been conducting clinical trials for Invossa in the United States, will have its first meeting with the FDA next month to resume the clinical trials. The Drug Ministry will decide on the change of the drug type or the cancellation of the authorization of Invossa after FDA decides on resuming the clinical trials.