Late-onset hemorrhagic cystitis after haploidentical hematopoietic stem cell transplantation in patients with advanced leukemia: differences in ATG dosage are key.

Late-onset hemorrhagic cystitis (LOHC) is a common complication following allogeneic hematopoietic stem cell transplantation (HSCT), but its cause remains obscure. More attention to risk factors for LOHC is needed. We retrospectively analyzed patients with advanced leukemia who had been treated with ATG-containing conditioning regimens to evaluate the influence of different doses of ATG on LOHC after haploidentical HSCT. Seventy-five patients undergoing haploidentical HSCT from January 2003 to February 2011 were evaluated. A total of 39 patients receiving transplantation before June 2008 were treated with high-dose ATG (10 mg/kg), whereas 36 patients received low-dose ATG (6 mg/kg) thereafter. LOHC occurred in 16.7% of the patients with low-dose ATG, and in 38.5% of the patients with high-dose ATG (P = 0.027). Univariate analysis showed high-dose ATG, male gender and cytomegalovirus reactivation to be significant risk factors for LOHC. However, only high-dose ATG (HR 2.96, 95% CI 1.143-7.663, P = 0.025) and male gender (HR 4.033, 95% CI 1.355-12.008, P = 0.012) were independent risk factors, as shown by multivariate analysis. In the setting of haploidentical HSCT, we concluded that LOHC is more prevalent in recipients of high-dose ATG and male patients. Future studies should focus on immune reconstitution and virus infection after haploidentical HSCT with 6 mg/kg or 10 mg/kg ATG.