Ps1558 Comparison of the Incidence and Outcomes of Transplant‐associated Thrombotic Microangiopathy Between Haploidentical and Matched Sibling Donor Hematopoietic Stem Cell Transplantation

Abstract

Background: Novel insights into the pathophysiology of GVHD highlighted the relevant role of the host inflammatory response governed by Bruton tyrosine kinase (BTK) signaling pathway. Ibrutinib is a first class, once daily inhibitor of BTK with proven efficacy in B cell lympho-proliferative diseases, was recently employed in corticosteroid-refractory chronic GVHD with encouraging overall response rates(Miklos et all, Blood 2017). We previously reported the results of 14 patients who received ibrutinib treatment for steroid-refractory cGVHD (Ilhan et all, ASH 2018) Aims: Herein, we share a real-life experience using ibrutinib in the treatment of streoid-refractory cGVHD in 30 patients from centers in Turkey. Methods: This multicenter retrospective study conducted in 9 stem cell transplant centers from Turkey included 30 adult patients diagnosed with steroid-refractory cGVHD. We treated off-label these patients from June 2017 to July 2018 with ibrutinib with a dose of 420 mg P.O. qday. Organ sites affected and cGVHD grading before starting ibrutinib were classified according to the National Institues of Health (NIH) 2014 criteria. Steroid refractory cGVHD was defined as any disease that failed to respond to previous immunosuppressive therapy with steroids at least 4 weeks or inability to taper it with or without additional immunosuppressive drugs.