Kolon TissueGene moves arthritis gene therapy into spine trial after FDA green light
Kolon TissueGene is marching its gene therapy candidate TG-C beyond the knee and into the spine, chasing a market three times larger than osteoarthritis even as questions from a 2019 Korean safety scandal trail close behind.
The Korean company said Tuesday it plans to launch a phase 1 trial in the U.S. next year to test TG-C in degenerative disc disease (DDD), after receiving FDA clearance in December 2023.
That approval was based on safety data from TG-C’s ongoing phase 3 trials in knee osteoarthritis. The same drug batch used in those trials will be used for the DDD study.
TG-C combines healthy donor cartilage cells with a genetically modified human cell line engineered to produce TGF-β1, a growth factor that reduces inflammation and promotes cartilage repair. The therapy is administered as a single intra-articular injection, originally developed for the knee.
Kolon plans to enroll 24 DDD patients starting in the second half of 2026, pending approvals from institutional review boards and biosafety committees in the U.S. The company aims to complete those reviews by the second quarter of next year.
While the FDA allowed Kolon to proceed based on knee safety data, the shift in indication introduces new concerns. Spinal discs sit near the spinal cord, and preclinical research has shown that elevated levels of TGF-β1 can contribute to disc degeneration. Elevated TGF-β1 can also trigger inflammation in joint cartilage, underscoring the need for precise dose control in both tissues.
According to a Kolon spokesperson, TG-C is engineered to maintain a stable and controlled dose at the injection site. “Too much can cause issues, so the formulation ensures stable dosing,” the spokesperson said. “That’s actually part of what TG-C is engineered to do.”
The therapy is composed of two liquids: one containing chondrocytes and the other carrying modified cells that produce TGF-β1. According to the company, direct injection of the protein would lead to rapid degradation and inflammation, whereas the cell-based delivery mechanism ensures localized and sustained expression.
TG-C was initially approved in Korea in 2017 under the name Invossa but had its license revoked in 2019 when regulators discovered that the second component of the therapy was made from kidney-derived cells, not cartilage-derived cells as originally disclosed. The fallout led to trading in Kolon TissueGene shares being suspended for over three years and triggered multiple lawsuits.
The FDA also imposed a clinical hold in 2019 after the cell origin issue surfaced. Kolon submitted additional safety data, prompting the FDA to lift the hold in 2020. Patient enrollment resumed in late 2021, and dosing in the knee trials wrapped in July 2024.
Kolon is now turning its attention to a larger commercial opportunity. According to Grand View Research, the global market for degenerative disc disease reached 14.8 trillion won in 2024, compared with 5.8 trillion won for knee osteoarthritis.
“We intend to extend TG-C to high-value degenerative musculoskeletal diseases,” Kolon TissueGene CEO Jeon Seng-ho said in a statement. “Spinal disorders, like knee osteoarthritis, affect vast numbers of patients, and current treatments are limited. Even early-stage clinical data could open doors to licensing deals.”