BACKGROUND In the past, conventional treatment strategies for transplant‐associated thrombotic microangiopathy (TA‐TMA) have not proven to be very effective. Recently, eculizumab which is a humanized monoclonal antibody that works as a terminal complement inhibitor has demonstrated promise in the treatment landscape of TA‐TMA. METHODS AND MATERIALS This was a single‐center retrospective analysis of 20 consecutive adult patients with TA‐TMA: 10 patients who received conventional therapy and 10 patients who received eculizumab‐based therapy. These patients had undergone allogeneic HSCT at MD Anderson Cancer Center between August 2011 and September 2016. RESULTS When comparing the treatment outcomes in the two cohorts, none of the patients in the conventional therapy group obtained a hematologic or complete response according to our response criteria whereas seven patients in the eculizumab group achieved a hematologic response with one patient achieving a complete response with organ recovery. In addition, overall survival at the end of assessment was 60% in the eculizumab cohort and 30% in the conventional cohort. One major difference in practice at our institution versus previously published studies is the management of immunosuppression. In a majority of patients, tacrolimus was continued or transitioned to sirolimus for GVHD prophylaxis. CONCLUSION Response rates and survival were improved for patients who were transitioned to sirolimus, so a two‐pronged approach of inhibiting complement along with providing an alternative effective immunosuppressive agent may be beneficial in the treatment of early onset TA‐TMA.

Background Currently, there are no prospective, randomized trials analyzing leflunomide for the treatment of cytomegalovirus infection or disease in allogeneic stem cell transplant patients. Objective The primary objective of this case series was to determine the clinical and virological responses of utilizing leflunomide as therapy for refractory cytomegalovirus infections, unresponsive to first-line therapy in allogeneic stem cell transplant patients. Additionally, patient and leflunomide specific characteristics were identified and determined in this descriptive case series. Methods This is a single-center, case series of adult allogeneic stem cell transplant patients with refractory cytomegalovirus infections receiving leflunomide between 1 January 2005 and 31 March 2015. Results A total of 14 patients with refractory cytomegalovirus infections received leflunomide. All patients received concurrent anti-cytomegalovirus therapy. Nine of 13 patients tested positive for phosphotransferase UL97 and/or viral DNA polymerase UL54 genotype mutations. Nine patients achieved a virological response with undetectable cytomegalovirus titers. Of the 13 patients with teriflunomide serum levels, eight patients maintained levels >40 micrograms/milliliter (mcg/mL). Common adverse effects were pancytopenia (n = 8) and elevated liver function tests (n = 4). Conclusions Despite current strategies, refractory or recurrent cytomegalovirus infection and disease remain a clinical challenge to treat in the stem cell transplant patient population. Leflunomide used in combination with other concomitant therapies use for refractory cytomegalovirus infection in clinical practice may be a safe and effective option in the allogeneic stem cell transplant patient population.