Clinical effects of recombinant thrombomodulin and defibrotide on sinusoidal obstruction syndrome after allogeneic hematopoietic stem cell transplantation

Sinusoidal obstruction syndrome (SOS) is a lethal complication after hematopoietic stem cell transplantation (HSCT). Defibrotide (DF) is the only drug internationally recommended for SOS treatment in Western countries. Recombinant human soluble thrombomodulin (rhTM), which is promising for the treatment of patients with disseminated intravascular coagulation, is also reported to be potentially effective for SOS. To clarify the safety and efficacy of DF and rhTM, we conducted a retrospective survey of these agents in Japan. Data from 65 patients who underwent allogeneic HSCT and received DF (n = 24) or rhTM (n = 41) for SOS treatment were collected. The complete response rates for SOS on day 100 were 50% and 54% in the DF and rhTM groups, respectively. The 100-day overall survival rates were 50% in the DF group, and 48% in the rhTM group. Several severe hemorrhagic adverse events were observed in one patient in the DF group and five patients in the rhTM group. The main causes of death were SOS-related death, and no patient died of direct adverse events of DF or rhTM. Our results suggest that rhTM, as well as DF, can be effective as a novel treatment option for SOS.