Optimal approach to prevent veno-occlusive disease following hematopoietic stem cell transplantation in children

Targeted busulfan-based reduced-intensity conditioning and HLA-matched HSCT cure hemophagocytic lymphohistiocytosis

Reduced-intensity/reduced-toxicity conditioning and allogeneic T-cell replete hematopoietic stem cell transplantation are curative in patients with hemophagocytic lymphohistiocytosis (HLH). Unstable donor chimerism (DC) and relapses are clinical challenges . We examined the effect of a reduced-intensity conditioning regimen based on targeted busulfan to enhance myeloid DC in HLH. The European Society for Bone and Marrow Transplantation-approved reduced-intensity conditioning protocol comprised targeted submyeloablative IV busulfan, IV fludarabine, and serotherapy comprising IV alemtuzumab (0.5-0.8 mg/kg) for unrelated-donor and IV rabbit anti-T-cell globulin for related-donor transplants. We assessed toxicity, engraftment, graft-versus-host disease (GHVD), DC in blood cell subtypes, and overall survival/event-free survival. Twenty-five patients from 7 centers were treated (median age, 0.68 year). The median total dose and cumulative area under the curve of busulfan was 13.1 mg/kg (6.4-26.4) and 63.1 mg/L × h (48-77), respectively. Bone marrow, peripheral blood stem cell, or cord blood transplants from HLA-matched related (n = 7) or unrelated (n = 18) donors were administered. Donor cells engrafted in all patients (median: neutrophils d+20/platelets d+28). At last follow-up (median, 36 months; range, 8-111 months), the median DC of CD15+ neutrophils, CD3+ T cells, and CD16+56+ natural killer cells was 99.5% (10-100), 97% (30-100), and 97.5% (30-100), respectively. Eight patients (32%) developed sinusoidal obstruction syndrome, resolving after defibrotide treatment. The 3-year overall survival and event-free survival rates were both 100%. None of the patients developed acute grade III to IV GHVD. Limited chronic GVHD was encountered in 4%. This regimen achieves excellent results with stable DC in patients with HLH.

Defibrotide in Severe Sinusoidal Obstruction Syndrome: Medicine and Economic Issues

In Europe, Defitelio (defibrotide) has a Market Authorization in curative treatment of severe sinusoidal obstruction syndrome (SOS) but not in prophylaxis (2013). In France, defibrotide has had a compassionate-use program since 2009. Today, the high cost of defibrotide remains a major hurdle for hospital budgets. Medicine and economic issues were evaluated for the 39 hospitals of the French Public Assistance-Hospitals of Paris (AP-HP). We analyzed literature reviews, consumption, and expenditures through AP-HP data in 2014 and patient profiles with defibrotide in the corresponding diagnostic-related groups (DRGs) and consulted a board of hematologists. Finally, 18 publications were selected. Between 2011 and 2014 consumption increased to €5.2M. In 2014, 80 patients receiving defibrotide were mainly ascribed to the DRG "hematopoietic stem cell transplantation" levels 3 or 4. The tariffs attributed to drugs (€3544 to 4084) cover a small part of treatment costs (€97,524 for an adult). French experts thus recommended a harmonization of indications in prophylaxis (off-label use), improvement of pretransplant care, and optimization of the number of vials used. The economic impact led experts to change their practices. They recommended the restriction of defibrotide use to SOS curative treatment and to high-risk situations in prophylaxis.

Defibrotide

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Defibrotide for the management of sinusoidal obstruction syndrome in patients who undergo haemopoietic stem cell transplantation

Sinusoidal obstruction syndrome, previously known as veno-occlusive disease (VOD/SOS), is a complication in patients undergoing haemopoietic stem cell transplantation (HSCT). Severe VOD/SOS, including progression to multi-organ failure, has resulted in a mortality of greater than 80%. Defibrotide's varying pharmacological actions, particularly on endothelial cells, make it is a useful agent to consider for prophylaxis and treatment of VOD/SOS. Barriers to its routine use include the high acquisition cost and the fact that neither the oral or parenteral formulations are licensed products in many countries at this time. This review summarises available literature on the use of defibrotide in the management of VOD/SOS. Publications consist predominantly of single centre cohort studies and case series. Available evidence indicates that defibrotide is effective in the management of VOD/SOS. Using defibrotide prophylaxis should also be considered, especially in the paediatric setting, where there are available results from a large, open label, randomized controlled trial. Patient outcome data from the larger studies and compassionate programs can inform consensus recommendations on dosing regimen and criteria for the treatment of VOD/SOS with defibrotide in the adult population. The reviewed literature indicates an effective and safe dose for treatment is 25mg/kg/day, continued for at least 14days or until complete response is achieved. Further studies are required to determine the optimal dose and duration of treatment in both paediatric patients and adults. Recent recommendations and a phase 3 trial using historical controls indicate that defibrotide should be included as a pharmacotherapy option in protocols guiding management of VOD/SOS.