Sirolimus-based graft vs. host disease (GVHD) prophylaxis is associated with higher incidence of veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) after allogeneic hematopoietic cell transplantation (HCT). However, whether the clinical manifestations and prognosis of VOD/SOS differs when diagnosed in the setting of sirolimus-based GVHD prophylaxis is not well studied. To address this question, we examined presenting features and treatment outcome of VOD/SOS
cases identified in a large retrospective cohort of consecutive HCT procedures (n = 818 total, sirolimus (SIR)/tacrolimus (TAC) n = 308, and methotrexate (MTX) or mycophenolate mofetil (MMF)/TAC n = 510). In multivariate analysis, sirolimus-based GVHD prophylaxis (p = 0.006, HR 3.33, 1.94-5.7) increased risk for VOD/SOS. A total of 58 patients were clinically diagnosed with VOD/SOS (SIR/TAC 38/308, 12.3%, vs. MTX or MMF/TAC 20/510, 3.9%). VOD/SOS diagnosed following SIR/TAC prophylaxis demonstrated later time of onset (median 39 vs. 26 days; p = 0.005), less severe hyperbilirubinemia (Bili > 2, 65% vs. 90% p = 0.04), lesser degree of weight gain (weight gain > 5%, 52% vs 80%, p = 0.04), and more frequent complete resolution of hepatic injury (79% vs. 55%, p = 0.05). Presenting features and natural history of VOD/SOS in the context of SIR/TAC GVHD prophylaxis differ and thus warrant particular clinical attention to later hepatic injury in these patients.