Ab0187 Ultrasound Features in Patients With Inflammatory Arthritis and Arthralgia Following Immune Checkpoint Inhibitor Therapy for Cancer: Results of a Multi-Centre Study

Background: Immune checkpoint inhibitors (ICIs) have transformed cancer management but immune related adverse events are common. ICI induced inflammatory arthritis (ICI-IA) occurs in 7% of patients but up to 43% report arthralgia 1. Imaging data in ICI-IA is largely retrospective and consists of case series/ small cohort studies. Given the rapidly expanding indications for ICIs, characterising the distribution and pattern of inflammation in ICI-IA is now of upmost importance to further our understanding of this condition and inform management. Objectives: To characterise the ultrasound (US) features of ICI-IA and arthralgia. Methods: Consecutive patients with new IA/arthralgia during or ≤6 months after ICI therapy were recruited from four Rheumatology centres. Relevant demographic/clinical information was collected. Physical examination and a comprehensive US protocol, assessing joints, tendons and entheses was carried out (Table 2). US synovitis was defined as power Doppler (PD) ≥1 + grey scale (GS) ≥1 or GS ≥2 ± PD (large joints), using the global OMERACT-EULAR score system (GLOESS) (Table 2). US bone erosions (BE) and tenosynovitis (TSV) were scored according to OMERACT. Enthesitis was defined as PD grade ≥1 at the enthesis plus entheseal thickening and/or hypoechoic areas, or PD at the enthesis grade >1. Results: Forty-eight patients with ICI-IA or arthralgia were recruited. Baseline characteristics are shown in Table 1. The prevalence and distribution of the US findings have been reported in Table 2. US synovitis was most prevalent in the wrist (52% IA, 32% arthralgia) and knee (69% IA, 14% arthralgia) joints. 15% IA and 5% arthralgia had BE in ≥1 joint (3 ulnar styloid, 1 metacarpophalangeal MCP 2, 1 MCP 5 and 1 proximal interphalangeal PIP 5). Furthermore, 50% IA and 18% arthralgia had TSV in ≥1 tendon and 31% IA and 23% arthralgia had enthesitis in ≥1 enthesis. In addition, 4% of IA and 9% arthralgia had TSV of the long head of the biceps tendon and 12% IA had subdeltoid bursitis. Of the 22 with arthralgia (no clinical synovitis), 11 (50%) had US synovitis in ≥1 joint, most commonly in the wrist, MCP and knee joints. Conclusion: Patients with ICI arthralgia/IA showed a wide spectrum of US abnormalities at the joint, tendon and entheseal level. Wrist, MCP and knee joints were the most affected. In those with arthralgia (without clinical swelling), 50% had US subclinical synovitis suggesting a much higher prevalence of musculoskeletal ICI toxicity than may be clinically obvious. A focused US of the wrist, knee and MCP joints may aid the diagnosis of ICI-IA in the absence of definite signs of IA. REFERENCES: 1 Abdel-Wahab. Rheumatology 2019. Acknowledgements: NIL. Disclosure of Interests: Kate Harnden: None declared, Andrea Di Matteo Janssen, Luca Di Geso: None declared, Rudolf Horvath: None declared, Jana Hurnakova: None declared, Tadashi Okano: None declared, Sana Sharrack: None declared, Didem Sahin Eroglu: None declared, Paul Emery Abbvie, Astra-Zeneca, BMS, Boehringer Ingelheim, Galapagos, Gilead, Janssen, MSD, Lilly, Novartis, Pfizer, Roche, Samsung, Abbvie, BMS, Lilly, Novartis, Pfizer, Roche, Samsung, Emilio Filippucci Abbvie, Amgen, Bristol-Myers Squibb, Janssen-Cilag, Lilly, Novartis, Pfizer and UCB Pharma, Kulveer Mankia Abbvie, Galapagos, UCB, Serac Healthcare, Deepcure, Zura Bio, AstraZeneca, Gilead, Lilly, Serac Healthcare.