Results of a Phase II Study to Determine the Efficacy and Safety of Genetically Engineered Allogeneic Human Chondrocytes Expressing TGF-β1.

Abstract

Genetically engineered chondrocytes virally transduced with a transforming growth factor (TGF)-<i>β</i>1 (TG-C [TissueGene-C]) expression vector have been shown to have potential benefits in the nonoperative management of knee osteoarthritis. Previous literature has reported on safe dosages of TG-C. Therefore, the purpose of this study was to evaluate the Phase II results and a 24-month efficacy of this injectable mixture compared with placebo in patients with Kellgren-Lawrence (K-L) grade III knee osteoarthritis. Specifically, we assessed (1) functional outcomes, (2) pain scores, (3) adverse events (AEs), and (4) magnetic resonance imaging (MRIs) findings. We performed a multicenter, double-blinded, placebo-controlled, and randomized study of adults who had K-L grade III knee osteoarthritis. A total of 102 patients were 2:1 randomized to TG-C at a dose of 3.0 × 10⁷ cells, or placebo injections between May 1, 2011 and October 31, 2012. Outcomes analyzed were knee joint function, pain, quality of life, adverse events, and MRI findings using the whole-organ magnetic resonance imaging score (WORMS) system. There were significant improvements in the International Knee Documentation Committee (IKDC) and visual analogue scale (VAS) scores in the TG-C cohort, when compared with the placebo cohort at weeks 12, 52, 72, and 104 (<i>p</i> < 0.05). No severe AEs were observed. Common AEs were arthralgia, joint inflammation, and joint effusion which were similar between both cohorts. Whole-knee MRIs at 12 months showed less progression of cartilage damage, infrapatellar fat pad-synovitis, and effusion-synovitis in the TG-C cohort. Patients who received TG-C had significant improvements in IKDC and VAS scores. These patients also reported less severe and frequent pain. Additionally, fewer patients treated with TG-C showed progression of cartilage damage, as well as less progression of infrapatellar fat pad synovitis and effusion-synovitis. Furthermore, treatment with TG-C was generally well tolerated with minor AEs. Therefore, based on these results, TG-C appears to be a safe and effective modality for the management of K-L grade III osteoarthritis.