Pre-transplant use of tyrosine kinase inhibitors and transplant associated thrombotic microangiopathy - a single centre analysis of incidence, risk factors and outcomes.

Transplant associated thrombotic microangiopathy (TA-TMA) is life-threatening complication post allogeneic stem cell transplant (ASCT). Risk factors and prognosis of TA-TMA are not well defined. We retrospectively studied consecutive ASCT patients with AML, ALL, and CML from January 2008 to March 2019 to study the incidence, risk factors, and outcomes of TMA. Definitive and probable TA-TMA was defined using Blood and Marrow Transplant Clinical Trials Network (BMT-CTN) and Cho criteria, respectively. Risk factors explored were age, gender, diagnosis, type of transplant, use of tyrosine kinase inhibitors (TKI) pre transplant, conditioning regimen, and acute GVHD. Standard statistical methods were used. Total 241 patients, 179 (74.2 %) males, median age of 29 years were studied. Diagnoses were AML in 104, ALL in 85 (Ph+ve 23) and CML 52. Total 26 (10.7%) patients (22 males) developed TA-TMA at median of day+102. On multivariate analysis, pre-HSCT TKI (OR 2.7, p = 0.028), haplo-HSCT (OR 3.16, p = 0.018) and presence of acute GVHD (OR 4.17, p = 0.003) were significant risk factors. With a median follow up of 60 months, median OS with and without TA-TMA was 18 and 97 months respectively (p = 0.021). The association of pre-HSCT with TKI with TA-TMA merits further exploration in prospective studies.