Treatment of active refractory rheumatoid arthritis with humanized monoclonal antibody campath‐1h administered by daily subcutaneous injection

Objective. To investigate the dose tolerance and potential clinical activity of a humanized antilymphocyte monoclonal antibody, CAMPATH‐1H (C1H), in patients with active, refractory rheumatoid arthritis (RA). Methods. Thirty adult patients with active, refractory RA were treated in an open‐label, 3‐center, dose‐escalation study of subcutaneously injected C1H. Six patients were assigned to each of 5 dosage groups (0.3, 1.0, 3.0, 10.0 or 30.0 mg/day), and received 10 daily injections of C1H over a 12‐day period. Results. Side effects occurred primarily during the first 1–2 days of dosing, and included mild fever, chills, nausea, vomiting, headache, and, in a minority of patients, hypotension. All patients developed some discomfort at the injection site. Self‐limited infections occurred in 5 patients during the 6‐month study period. Peripheral blood lymphocyte counts fell promptly after initial dosing and recovered slowly, usually over 2–3 months. Serum antibodies to C1H developed in 54% of patients following treatment. Clinical improvement was observed in 56% of patients, based on the composite Paulus criteria, with a median time‐to‐response of 22 days and a median response duration of 32 days. Conclusion. C1H is a lymphocyte‐depleting antibody that exhibits biologic potency when administered subcutaneously to patients with refractory RA. Its use is associated with mild to moderate toxicity and short‐term amelioration of disease activity.