Randomized, double-blind, placebo-controlled, parallel-group trial of sirolimus for tocilizumab-resistant idiopathic multicentric Castleman disease: Study protocol for clinical trial

BACKGROUND: Idiopathic multicentric Castleman disease (iMCD) is a rare lymphoproliferative disorder of unknown etiology with systemic symptoms that include fever, night sweats, weight loss, and fatigue. Although tocilizumab (TCZ), which is a recombinant, humanized, anti-human interleukin 6 receptor monoclonal antibody, has been recommended to treat patients with iMCD, 40% of patients with iMCD do not achieve complete remission with TCZ treatment. METHODS/DESIGN: In this phase II, investigator-initiated, multicenter, double-blind, randomized, parallel-group trial, the efficacy and safety of sirolimus will be compared with placebo in patients with TCZ-resistant iMCD. The study will be conducted in 8 centers in Japan. Participants (n = 20) will be randomly assigned to receive 2 mg of oral sirolimus (n = 10) or placebo (n = 10) once daily for 16 weeks. The primary endpoint is a decrease in CHAP score by ≥1 from baseline at 16 weeks. Secondary endpoints include levels of hemoglobin, albumin, and C-reactive protein; change in CHAP score; SF-36 Health Survey Questionnaire; physician global assessment (100 mm visual analog scale); patient global assessment (100 mm visual analog scale) at 2, 4, 8, 12, and 16 weeks; change in lymphadenopathy at 16 weeks; and pharmacodynamic assessment, including the measurement of whole blood sirolimus level. DISCUSSION: This clinical trial will provide evidence of efficacy and safety of sirolimus as a potential new therapeutic agent for patients with TCZ-resistant iMCD. TRIAL REGISTRATION: This study was registered with the Japan Registry of Clinical Trials as jRCT2071190029 on October 8, 2019.