Risk factors for hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation in a letermovir‐exposed CMV‐free population receiving PTCy

Abstract

Hemorrhagic cystitis (HC) is a highly impacting complication in allogeneic hematopoietic stem cell transplantation (HSCT), occurring in 12%–37% of patients. The impact of transplant‐ and patient‐specific variables has been described, with a possible role for JCV and BKV, which may be cooperating with cytomegalovirus (CMV). Here, we analyze 134 letermovir‐exposed, CMV‐free patients, treated with the same cyclophosphamide‐based graft‐versus‐host disease (GVHD) prophylaxis, describing risk factors for HC. The overall incidence of HC was 23%. Patients with HLA mismatched transplant, higher comorbidity score, and receiving three alkylating agents with TBF (thiotepa, busulfan, and fludarabine) conditioning regimen had a higher risk of HC in multivariate analysis (OR: 4.48, 6.32, and 1.32, respectively). A HC‐score including male gender, TBF conditioning, and HLA‐mismatch stratifies the risk of HC in the first 100 days after HSCT. The role of BKV and JCV was not highly impacting in those patients, suggesting a possible synergistic effect between CMV and JCV in causing HC. HC can be interpreted as the combination of patient‐related factors, chemotherapy‐related toxicities—especially due to alkylating agents—and immunological elements.