Haploidentical Stem Cell Transplantation with Post-transplantation Cyclophosphamide in High-Risk Chronic Granulomatous Disease Patient with Invasive Mucormycosis

HLA-haploidentical stem cell transplantation for chronic granulomatous disease: an EBMT-IEWP retrospective study

ABSTRACT

Chronic granulomatous disease (CGD) is an inborn error of immunity characterized by defective NAD phosphate oxidase function, leading to impaired microbial killing, recurrent infections, and granulomatous inflammation. Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for CGD, particularly effective when a fully HLA-matched donor is available. However, the place of HLA-haploidentical HSCT remains less established. This retrospective multicenter study analyzed outcomes of 64 patients with CGD (53 males; 46 with X-linked CGD) who underwent a first HSCT with HLA-haploidentical family donors, with either in vitro T-cell receptor (TCR)αβ/CD19 depletion or in vivo depletion using posttransplant cyclophosphamide (PTCY). The mean age at transplant was 5.8 years (range, 0-33). Patients exhibited a high disease burden before HSCT, with 45% experiencing infections in the 6 months before HSCT and 67% exhibiting inflammation. Outcomes in the entire cohort showed a 3-year overall survival, event-free survival (EFS), and grade 3 to 4 graft-versus-host disease (GVHD)-free EFS of 75.9%, 70.2%, and 56.1%, respectively, and were not affected by the type of depletion or age. The cumulative incidence (CI) of primary graft failure (PGF) was 20.6%. The CI of grade 2 to 4 acute GVHD was higher in the PTCY group (P = .04), whereas the CI of grade 3 to 4 GVHD was not. These results indicate that HLA-haploidentical HSCT is a feasible transplant option for patients with CGD lacking HLA-matched donors. Further refinement of transplant protocols is necessary to mitigate graft failure and acute GVHD, ultimately improving access and outcomes for this life-saving therapy.

Inborn errors of immunity: A field without frontiers

The study of primary immunodeficiencies or inborn errors of immunity continues to drive our knowledge of the function of the human immune system. From the outset, the study of inborn errors has focused on unraveling genetic etiologies and molecular mechanisms. Aided by the continuous growth in genetic diagnostics, the field has moved from the study of an infection dominated phenotype to embrace and unravel diverse manifestations of autoinflammation, autoimmunity, malignancy, and severe allergy in all medical disciplines. It has now moved from the study of ultrarare presentations to producing meaningful impact in conditions as diverse as inflammatory bowel disease, neurological conditions, and hematology. Beyond offering immunogenetic diagnosis, the study of underlying inborn errors of immunity in these conditions points to targeted treatment which can be lifesaving.