title: 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.
abstract: 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).
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  ClinicalTrials.gov identification numbers NTC 00449696 and NTC 00450112.
authors.affiliation: Division of Immunology and Rheumatology, Stanford University School of Medicine, Palo Alto, CA, USA.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Strand
authors.affiliation: North American Business Unit, Seikagaku Corporation, Chiyoda-ku, Tokyo, Japan.
authors.forename: Sooyeol
authors.initials: S
authors.lastname: Lim
authors.affiliation: Clinical Development Department, Research & Development Division, Seikagaku Corporation, Chiyoda-ku, Tokyo, Japan. junko.takamura@seikagaku.co.jp.
authors.forename: Junko
authors.initials: J
authors.lastname: Takamura
mesh_terms: D000368:Aged; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage*; D007270:Injections, Intra-Articular; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000188:drug therapy*; D055675:Viscosupplements / Q000008:administration & dosage*
chemical_list: D055675:Viscosupplements; D006820:Hyaluronic Acid
keywords: Cross-linked HA; Gel-200; Hyaluronic acid; Intra-articular; Knee; Osteoarthritis; Viscosupplementation