HONG KONG – After more than a decade of development, Tissuegene Inc. and its Asia licensee, Kolon Life Science Inc., received approval from South Korean regulatory authorities to market Invossa-K, a gene therapy for degenerative arthritis.

The most advanced candidate of Tissuegene's pipeline, Invossa-K is a first-in-class cell-mediated gene therapy designed to effectively treat osteoarthritis of the knee via the single intra-articular injection. Kolon Life Science, a subsidiary of South Korean conglomerate Kolon Group, is the local manufacturer of the drug.

Kolon said that by injecting regenerating genes into cartilage cells, pain relief can last for one to two years.

The South Korean Ministry of Food and Drug Safety (MFDS) gave the marketing green light to Invossa based on a phase III trial conducted in the country with two primary endpoints: International Knee Documentation Committee and Visual Analog Scale scores, which were selected to demonstrate improvement in pain and function.

Data from the phase III trial have not yet been publically disclosed, according to Tissuegene's Steve Birnbaum, business development director.

Though the experiments in Korea were not of sufficient length to see the structural changes necessary to prove it was a disease-modifying osteoarthritis drug (DMOAD), a U.S.-based, 1,000-patient, two-year phase III trial is focused on achieving DMOAD, Birnbaum said.

"Invossa's effect of improving structures such as cartilage regeneration did not show any difference compared to the control group," said the ministry in a statement. "The range of prescriptions was also limited to moderate patients who failed medication and physical therapy. The degrees of knee osteoarthritis are doubtful, light, moderate and severe. Invossa can be prescribed to third-stage 'moderate' patients only."

Kolon Life Science's stock price (KOSDAQ:102940) fell upon release of the news. "Kolon's stock dipped down 9.7 percent [on July 13], partly because the MFDS seems to have focused on categorizing Invossa as a treatment instead of a DMOAD," Lee Sang-won, an analyst at Hanwha security, told BioWorld. "But I think this is not something to be disappointed with, since cartilage regeneration effects can be determined via long-term observation in a large-scale clinical trial that will be conducted in the U.S."

Tissuegene's chairman and CEO, Woosok Lee, said in a statement that he is very optimistic about the future of the drug. "We are excited to launch the world's first cell and gene therapy for knee osteoarthritis and potentially the world's first disease-modifying osteoarthritis drug," he said.

"This approval is the first critical step toward a global launch for this innovative, novel cell and gene therapy technology that will address one of the most pressing unmet medical needs," said Lee.

According to the MFDS, only four gene therapy products have been licensed by major advanced pharmaceutical countries such as the U.S. and Europe. Among them, Invossa is the first to specifically target knee arthritis.

In preparation for Invossa's launch, roughly $167 million will be used to expand Kolon's Chungju Plant in North Chungcheong province.

Invossa is expected to start sales in South Korea as early as September this year.

Apart from having Invossa approved, Tissuegene and Kolon have been actively exporting its technology overseas.

Last November, Tissuegene and Kolon Life Science signed an agreement on the development and commercialization of Invossa with Japan's Mitsubishi Tanabe Pharma Corp. Under the contract, Tissuegene will receive an up-front payment of $24 million plus milestone payments amounting to $415 million from the Japanese company.

Tissuegene said the deal "represents the largest single-territory deal on record for Korea" and that the company is to receive double-digit marketing royalties after the product is launched.

Founded in 1999, Tissuegene is slated to go public on South Korea's secondary Kosdaq market in September with an aim to raise up to $260.9 million. According to Korea Exchange, the U.S.-based company has filed for a preliminary review on June 15 on its plan for an IPO of 1.5 million shares.

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