Acquired C1-Inhibitor Deficiency: 7 Patients Treated with Rituximab

Acquired C1-inhibitor deficiency can occur secondary to excessive C1-inhibitor consumption (type I) and be associated with a lymphoid hemopathy, or linked to the presence of anti-C1-inhibitor autoantibodies (type II) in a context of an isolated monoclonal gammopathy, sometimes associated with lymphoproliferation. Efficacy of danazol, tranexamic acid and/or corticosteroids is inconstant. Rituximab efficacy against type II angioedema has been reported. Description of 7 rituximab-treated patients, 6 with type II acquired angioedema and 1 with type I. Clinical efficacy (only for type II) was complete for 3, partial for 2 and 2 were therapeutic failures. Only 2 patients had improved biological parameters, with normalization of their C1-inhibitor levels and diminished anti-C1-inhibitor autoantibodies, observed 1-9 months after the last infusion of the second rituximab cycle. An associated lymphoproliferation did not affect the response to treatment. Rituximab efficacy in the treatment of acquired angioedema is inconstant and might require repeated cycles.