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
• Glucocorticoid dependence at any time before enrolment, defined by either:
• Patients requiring prednisone at a dose of at least 10 mg daily (or equivalent) OR
• Patients for whom at least 1 glucocorticoid taper failed to control the disease activity

• 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