Evidence for safety of retreatment with a single intra-articular injection of Gel-200 for treatment of osteoarthritis of the knee from the double-blind pivotal and open-label retreatment clinical trials

Background: Gel-200 is a cross-linked hyaluronate single-injection device for treatment of osteoarthritis pain in the knee. This report summarizes new analyses of the safety of retreatment with Gel-200 from the 13-week, pivotal, multicenter, randomized controlled trial (RCT) followed by an open-label extension trial (OLE). Methods: 379 patients were enrolled in the RCT [Gel-200; phosphate-buffered saline (PBS)]. Safety of retreatment with Gel-200 was assessed by comparing adverse events (AEs) and device-related AEs reported through Week 4 following retreatment with Gel-200 to those reported in patients receiving their first injection in the OLE. Results: 350 patients completed the initial RCT (231 Gel-200; 119 PBS); 258 patients enrolled in the OLE (162 Gel-200; 96 PBS). In total, 202 patients (125 Gel-200; 77 PBS) qualified for retreatment, while 56 (37 Gel-200; 19 PBS) did not. There were no significant demographic or disease characteristic differences between Gel-200 patients who were and were not retreated; those who were not eligible for retreatment experienced greater pain relief from Gel-200 in the RCT by all effectiveness endpoints (all p < 0.001), without differences in their safety profile. In the OLE, the safety of Gel-200, including percentages of patients who experienced any AEs (p = 0.547) and device-related AEs (p = 0.521), did not significantly differ between those receiving a second versus a first injection of Gel-200 following PBS in the RCT. Conclusion: In the OLE, the safety of a second injection of Gel-200 was comparable to that of a first injection and effectiveness was similar, as previously reported.