Although hemophagocytic syndrome (HS) featuring secondary hemophagocytic lymphohistiocytosis (HLH) has a grave prognosis, little is known about the natural course of the disease. Patients who showed the clinical features of HLH as well as tissue-proven hemophagocytosis when seen at Asan Medical Center between 1999 and 2010 were included in this analysis. Patients with proven lymphoma were excluded. The median age of our 23 study patients was 49 years. Epstein-Barr virus was suspected to have caused HS in 16 (70%) patients and hepatitis A virus in one patient. Twenty-two patients were treated, 13 according to the HLH protocol and nine using immunosuppressive agents such as corticosteroid and/or cyclosporine. Five patients undertook allogeneic hematopoietic cell transplantation (HCT) during their treatment-dependent relapse (n = 4) or responsive status (n = 1). After the median follow-up of 180 days, 17 (74%) died and six (26%) were alive. The median time from initial presentation until death was 41 days among those patients who died. The serum fibrinogen level ≥166 mg/dL determined at the initial visit was significantly associated with the survival time according to univariate analysis. The low histiocyte proportion in bone marrow and early initiation of treatment tended to correlate with a favorable outcome. On multivariate analysis, serum fibrinogen ≥166 mg/dL (hazard ratio, 0.175, P = 0.018) was an independent clinical factor for determining the patient survival time. Despite appropriate patient management, the outcome of HS featuring HLH was grave. The serum fibrinogen level at the initial presentation was significant, and selected patients obtained some benefit from allogeneic HCT.

Our results indicate that the BuFlu regimen is not a suitable replacement for the BuCy regimen in young adults who are eligible for myeloablative conditioning therapy for allogeneic HCT.

Intravenous (i.v.) busulfan can produce a more consistent pharmacokinetic profile than oral formulations can, but nonetheless, significant interpatient variability is evident. We investigated the influence of polymorphisms of 3 GST isozyme genes (GSTA1, GSTM1, and GSTT1) on i.v. busulfan clearance. Fifty-eight adult patients who received 3.2 mg/kg/day of busulfan as conditioning for hematopoietic cell transplantation were included in this study. Stepwise multiple linear regression demonstrated that GSTA1 variant GSTA1∗B (P = .004), GSTM1/GSTT1 double-null genotype (P = .039), and actual body weight (P = .001) were significantly associated with lower clearance of i.v. busulfan. A trend test analyzing the overall effect of GST genotype on busulfan pharmacokinetics, combining GSTA1 gene polymorphism and the number of GSTM1- and GSTT-null genotypes, showed a significant correlation between GST genotype and busulfan clearance (P = .001). The clearance of i.v. busulfan was similar between patients with GSTA1∗A/∗A and GSTM1/GSTT1 double-null genotypes and those with GSTA1∗A/∗B and GSTM1/GSTT1 double-positive genotypes. In conclusion, a pharmacogenetic approach using GST gene polymorphisms may be valuable in optimizing the i.v. busulfan dosage scheme. Our results also highlight the importance of including polygenic analyses and addressing interactions among isozyme genes in pharmacogenetic studies.