FRI0166 RADIOSYNOVIOTHESIS WITH YTTRIUM90: A CANADIAN EXPERIENCE
Authors: Nadil Zeiadin, Eric Turcotte, Emmanouil Rampakakis, Helena Senta, John Sampalis, Carter Thorne
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Radiosynovectomy (RSO) has been used since 1952 for treatment of refractory synovitis. <sup>90</sup>Yttrium in a colloidal form has been approved in several countries as a RSP radiopharmaceutical agent for intra-articular treatment of synovial hypertrophy. In comparison to surgical synovectomy, RSO produces equivalent results, costs less, allows the patient to remain ambulatory and can be repeated. However, there are currently no RSO radiopharmaceuticals approved in Canada. <h3>Objectives:</h3> 1. Establish safety of Yttrium-90 citrate synovectomy in a Canadian cohort <i>2.</i> Determine the therapeutic value of Yttrium-90 citrate in patients with refractory synovitis in a Canadian cohort. <h3>Methods:</h3> Adult (≥18yo) patients with symptomatic, refractory inflammatory mono- or oligoarthritis were included for RSO with Yttrium-90 citrate as part of a phase-III, prospective, open-label non-controlled trial. All patients were required to have failed 6-months of medical therapy and 2 intraarticular injections and have minimal evidence of cartilage or bone destruction. Only large and medium-sized joints were included (i.e. knees, ankles, wrists and elbows). The dose of Yttrium was adjusted based on the size of joint. Follow-up evaluations were done at 3, 6 and 12 months after RSO. Safety was assessed by patient and clinician reported adverse events. Clinical response was measured by improvement in joint tenderness, effusion and range of motion. <h3>Results:</h3> A total of 74 patients and 83 joints (88% knees) were treated with Ytrium-90 citrate. The underlying diagnosis included 25.7% RA, 34% SpA, 11% JIA, and 30.3% other inflammatory arthritis. Complications included 3 post-RSO flares, 1 septic joint and 2 injection site skin infections. Joint tenderness was reported in 93.8% of joints at baseline, compared to 50.0% at 3mo (p&lt;0.001), 55.6% at 6mo (p&lt;0.001) and 40.4% at 12mo (p&lt;0.001). Joint effusion was present in 95.1% of joints at baseline, 44.3% at 3mo (p&lt;0.001), 51.4% at 6mo (p&lt;0.001) and 47.4% at 12mo (p&lt;0.001). 73.9% of joints had improvement in range of motion at 3mo, 55.9% at 6mo and 60.7% at 12mo. <h3>Conclusion:</h3> These results confirm the clinical efficacy and safety of Yttrium90-citrate RSO for refractory synovitis with a sustained clinical benefit at 12 months. This is the first such study in a Canadian cohort. RSO with Ytrium is a safe alternative to surgical synovectomy in refractory cases. <h3>Disclosure of Interests:</h3> Nadil Zeiadin: None declared, Eric Turcotte: None declared, Emmanouil Rampakakis : None declared, Helena Senta: None declared, John Sampalis Employee of: JSS Medical Research, Carter Thorne Grant/research support from: Investigator-initiated studies: Amgen, Pfizer. RCTs: Abbvie, Celgene, CaREBiodam, Novartis, Pfizer, Consultant for: Advisory board: Abbvie, Amgen, Celgene, Lilly, Medexus/Medac, Merck, Novartis, Pfizer, Sanofi. Consultant: Abbvie, Centocor, Janssen, Lilly, Medexus/Medac, Pfizer, Speakers bureau: Medexus/Medac