Phase 2 study using oral thalidomide-cyclophosphamide-prednisone for idiopathic Multicentric Castleman disease

Idiopathic multicentric Castleman disease (iMCD) is a rare lymphoproliferative disorder. The anti–interleukin 6 (IL-6) therapy siltuximab is not available everywhere, and is not effective for over one-half of patients. Alternative treatment approaches are urgently needed. In the first iMCD clinical trial directed against a target other than IL-6 signaling, we investigated a thalidomide-cyclophosphamide-prednisone (TCP) regimen in newly diagnosed iMCD patients. This single-center, single-arm, phase 2 study enrolled 25 newly diagnosed iMCD patients between June 2015 and June 2018. The TCP regimen (thalidomide 100 mg daily for 2 years; oral cyclophosphamide 300 mg/m 2 weekly for 1 year; prednisone 1 mg/kg twice a week for 1 year) was administered for 2 years or until treatment failure. The primary end point was durable tumor and symptomatic response for at least 24 weeks. Twelve patients (48%) achieved the primary end point with no relapse, 3 patients (12%) demonstrated stable disease, and 10 patients (40%) were evaluated as treatment failure. Even when considering all patients, there were significant ( P