Early Adalimumab Induction for Immune Checkpoint Inhibitor Associated Inflammatory Arthritis

Inclusion Criteria: • Patients are deemed eligible for study participation if they meet all the following: Adult patients (age 18 or older) New (within the last 6 months prior to enrollment) inflammatory arthritis defined by any of the following at the time of screening (either on physical exam or by ultrasound) by a certified rheumatologist: 1 or more swollen joints OR 1 or more tenosynovitis OR 1 or more enthesitis Arthritis onset with taking ICI therapy OR within 4 weeks of stopping ICI therapy including CTLA-4, PD-1, and PDL-1 inhibitors Initiation of ICI therapy must predate the onset of inflammatory arthritis Arthritis either does not respond completely to prednisone doses of 10mg (equivalent) OR recurs with prednisone taper below 10mg daily. Negative tuberculosis (TB) status within the past 12 months (TB skin test or quantiferon) for the patients in the adalimumab group. If not available, the status should be confirmed within 6 months of enrollment in the study (adalimumab group only) Written informed consent provided by patient or power of attorney Exclusion Criteria: Patients are excluded if they meet any of the following: Previous diagnosis of inflammatory arthritis or other rheumatic disease (prior to current acute episode) Including but not limited to: rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, Sjogren's syndrome, psoriatic arthritis, reactive arthritis, ankylosing spondylitis, systemic vasculitis, undifferentiated inflammatory arthritis, undifferentiated connective tissue disease Tenosynovitis, synovitis or enthesitis attributed to another cause, fracture or acute gout/CPPD flare. Presence of a contraindication to adalimumab therapy Any of the following in the 7 days prior to initiation of adalimumab: positive tuberculin skin test (>5mm induration within 48 to 72 hours) or positive quantiferon, evidence of untreated active infection including fungal infection, opportunistic infection, hepatitis B/C, or HIV Personal history of congestive heart failure Personal or family history of demyelinating neurologic disease History of previous TNF inhibitor use Current use of other disease modifying agents including: Chloroquine, Sulfasalazine, Azathioprine, 6-MP, and Leflunomide Presence of a concomitant non-rheumatic irAE which required systemic immunosuppression within the past 3 months e.g. pneumonitis, hepatitis, colitis, scleritis, nephritis Require chronic steroid treatment for adrenal insufficiency or another medical reason other than ir-IA Pregnancy, breastfeeding or childbearing potential without practicing highly effective contraception. Inability to participate in follow-up visits