T Cell Depleted Haploidentical Hematopoietic Stem Cell Transplantation for Patients with Familial Hemophagocytic Lymphohistiocytosis Who Do Not Have Matched Family Donors: Experience in Oman

Familial hemophagocytic lymphohistiocytosis (FHLH) is a potentially fatal disorder of immune regulation. Management includes chemotherapy followed by hematopoietic stem cell transplantation (HSCT). T cell depleted (TCD)-haploidentical HSCT could be an option for those patients who do not have HLA matching family donor. The objective of this study was to report on the outcome of TCD-haploidentical HSCT in patients with FHLH who underwent transplantation at Sultan Qaboos University Hospital (SQUH). This is a retrospective report on 12 patients with FHLH who received TCD- haploidentical HSCT at SQUH between August 2010 and December 2018. Epidemiologic characteristics and details on the transplantation procedures and complications were collected from patients’ electronic records. Twelve patients with FHLH received TCD-haploidentical HSCT after a myeloablative conditioning regimen composed of treosulfan/thiotepa/fludarabine/anti-thymocyte globulin and rituximab. The mean age at transplantation was 11.67 ± 8 months. All patients had Perforin gene mutations, except 1 patient who had an UNC-13D mutation. Most patients received TCRαβ⁺/CD19⁺ depleted grafts for faster immune reconstitution. Seven patients (58.3%) have been cured with a mean follow-up duration of 3.44 years. Four patients died of multiorgan failure secondary to gram-negative sepsis. One patient had primary graft failure, and 2 patients had mild graft-versus-host disease. Two patients had Pneumocystis carinii pneumonia, 2 had adenoviremia, and 9 patients had cytomegalovirus (CMV) viremia. Among patients with CMV viremia, 2 had evidence of disease (retinitis, enteritis). All patients with CMV viremia were treated successfully with foscarnet pre-engraftment and ganciclovir postengraftment, respectively. TCD-haploidentical HSCT could be a viable option for patients with FHLH who do not have HLA matching family donors. Infectious complications are the leading cause of death in that setting. CMV viremia was the most frequently encountered infectious complication.