PB2320 PHASE II STUDY OF IMATINIB MESYLATE PLUS MYCOPHENOLATE MOFETIL FOR PEDIATRIC STEROID‐REFRACTORY SCLEROTIC/FIBROTIC TYPE CHRONIC GRAFT‐VERSUS‐HOST DISEASE

Abstract

Background:Chronic graft‐versus‐host disease (cGVHD) is the most common late complication following allogeneic stem cell transplantation. Sclerotic/fibrotic cGVHD is one of the severe type, and often refractory to standard and secondary therapy.Aims:In this study, we evaluated the efficacy and safety of imatinib mesylate and mycophenolate mofetil (MMF).Methods:In non‐randomized, open‐label, single‐arm, multi‐center, prospective phase II study, we enrolled patients with steroid‐refractory sclerotic/fibrotic type cGVHD. Participants were treated with MMF at a dose of 15‐20 mg/kg (maximum 1 g) bid and imatinib mesylate at the initial dose of 260 mg/m2/day (maximum 400 mg) in combination with previous cGVHD treatment. The primary endpoints was overall (complete and partial) response rate at 1 year. Secondary endpoints included safety, quality of life, discontinuation of steroid and overall survival (OS) rate.Results:A total of 13 patients were enrolled between October 2013 and July 2017. The median age was 10.4 years (range 5.0‐20.1 years). Five of the 13 patients had previously experienced acute GVHD. The diagnoses were acute lymphoblastic leukemia in 5, acute myeloid leukemia in 3, chronic granulomatous disease in 3, neuroblastoma in 1 and hemophagocytic lymphohistiocytosis in 1 patient. Nine of the 13 patients achieved partial response (PR), 2 showed stable diseases (SD), and 1 died of pulmonary infection and progression of chronic lung GVHD. The remaining 1 patient died of primary disease progression. The overall response rate was 69.2 %. Nine of the 13 patients were able to reduce or discontinue steroids. Among 13 patients, 6 patients showed improvements in Lee cGVHD symptom scale score to assess quality of life. Common adverse events included grade 1‐2 liver enzyme, creatinine elevations and fever. The 2‐ and 5‐year OS rate was 76.9% and 67.3%, respectively.Summary/Conclusion:Although limited by a small sample size, Gleevec plus MMF for cGVHD showed promising results with acceptable toxicity.