Background Sinusoidal obstruction syndrome (SOS) is an important non-haematological toxicity in patients who have received chemotherapy for haematopoietic stem cell transplantation (HSCT). In March 2013, European Medicines Agency refused marketing authorisation for the orphan drug defibrotide to prevent and treat SOS. In July 2013, after re-examination, defibrotide had a new positive opinion for marketing authorisation but only for treatment.

Purpose To investigate the effectiveness, safety and cost of defibrotide for SOS.

Materials and methods Retrospective observational study (Period: January 2009–September 2013). We analysed patients with SOS treated with defibrotide. Response criteria were defined as total serum bilirubin <2 mg/dl and resolution of multiple organ failure (MOF), including renal (recovery of normal creatinine value and lack of dialysis dependence), pulmonary (no oxygen dependence) and central nervous system (absence of encephalopathy) function. Evolution of the Baltimore criteria, including hepatomegaly, ascites and weight gain was measured. Secondary endpoint was survival by 100 days post-HSCT. Adverse events related to defibrotide administration were also retrieved.

Results Eleven patients (five adults (mean age: 55.7(SD = 4.3) years) and four children (3.1(SD = 1.3)) received defibrotide at a dose of 6.25 mg/kg every 6 h (two patients received 10 mg/kg/6 h). Median duration of treatment was 9 days (range: 5–25).

Overall complete response was achieved in seven patients (63.6%), all four children and only three adults. 45.5% of patients had completely recovered from hepatomegaly at the end of defibrotide administration. Six of the eight patients with ascites and one patient with encephalopathy recovered their normal status. All patients reduced their weight gain after defibrotide treatment. 100 day post-HSCT survival was 72.7%.

Three patients presented haemorrhagic episodes during defibrotide treatment (two gastrointestinal episodes and one nasal bleeding). Median cost per patient was 19,180 € (range 5,480–41,100 €).

Conclusions According to our limited results, defibrotide is an effective option for SOS treatment in children, although cost per patient is high. Cost-effectiveness studies comparing treatment for SOS with and without defibrotide are needed.

No conflict of interest.