Kolon TissueGene's Knee Osteoarthritis Therapy Fails Phase 3 Trial

Kolon TissueGene has reported that a phase 3 trial of its cell-based gene therapy TG-C failed to meet its co-primary endpoints in patients with osteoarthritis of the knee (knee OA).

The trial enrolled 531 patients across 27 US sites, comparing intra-articular injections of TG-C against placebo. TG-C combines human allogeneic chondrocytes with an irradiated human embryonic kidney-derived cell line engineered to express TGF-β1. At one year, patients receiving TG-C showed no statistically significant improvement in knee function or pain compared with those on placebo. The trial also missed its key secondary endpoints.

The candidate has a troubled regulatory history. South Korean authorities approved TG-C in 2017 but withdrew that approval two years later following a discrepancy over the cell types used in the therapy. The US trial itself was delayed by an FDA hold and began enrolling patients four years after it was first registered.

Kolon says it will wait for results from a second, near-identical phase 3 trial, due in October, before deciding on next steps for the programme. That study shares the same treatment arms, co-primary endpoints and eligibility criteria as the one that has just failed.

The setback adds to a difficult track record for knee OA drug development. Ampio Pharmaceuticals wound down in 2024 after its lead candidate stalled at the preclinical stage and Centrexion Therapeutics' CNTX-4975 failed to outperform placebo in its own phase 3 trial.

Not every program in the space has struggled - Flexion Therapeutics secured FDA approval for its knee OA treatment Zilretta in 2017 and was acquired by Paciria BioSciences in 2021.