AB1579 ULTRASOUND JOINT ASSESSMENTS INCREASE DETECTION OF POLYARTICULAR JOINT INVOLVEMENT IN CHECKPOINT INHIBITORS-INDUCED ARTHRITIS

Background CheckPoint Inhibitors (CPI) Induced arthritis (IA) is an immune related adverse event (irAEs) occurring in 0.5 to 2% of CPI-treated patients between 3 weeks up 24 months after initiation therapy. IA usually described as a seronegative oligoarticular inflammatory joint disease but has been for long underdiagnosed and inappropriately evaluated. Objectives To evaluate the added value systematic ultrasound assessment these by rheumatologist. Methods Patients referred their oncologist Rheumatology Department suspected had clinical swollen count (GE Logiq E9 Ultrasound Machine with ML6-15-D Matrix Linear Probe). Target joints were elbows, wrists, MCP 2-5, knees, ankles MTP1-5. The performed was compared one made rheumatologist US assessment. A considered positive case grey-scale ≥ 1 scale 3. Results 9 (6 males females) assessed. Mean age 66.1 years (SD 11 years). 4 treated metastatic melanoma, renal cell carcinoma (RCC), lung cancer, uterine cancer bladder carcinoma. They received monotherapy pembrozilumab (4/9), nivolumab (2/9), atezolimumab (1/9), darvalumab (1/9). None corticosteroids. 5 out (swollen <5) presentation oncologist, 2 polyarticular ≥5) PMR-like presentation. Whereas rheumatological assessments confirmed diagnoses oncologists, oligoarticular-labelled involvement assessements. In disease, showed rheumatoid factors (RF) or anticitrullinated peptides antibodies (ACPAs). Figure Number (SJC) each patient according Conclusion this small group CPI-IA, we found that led better classification involvement, present majority cases. Our results emphasise importance multidisciplinary approach support use CPI-IA patients. REFERENCES: NIL. Acknowledgements: Disclosure Interests Declared.