Escalated Dose Donor Lymphocyte Infusion Treatment in Patients with Primary Immune Deficiencies After HSCT with Reduced-Intensity Conditioning Regimen

The graft versus leukemia effect: donor lymphocyte infusions and cellular therapy

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for many hematologic malignancies as well as non-malignant conditions. Part of the curative basis underlying HSCT for hematologic malignancies relies upon induction of the graft versus leukemia (GVL) effect in which donor immune cells recognize and eliminate residual malignant cells within the recipient, thereby maintaining remission. GVL is a clinically evident phenomenon; however, specific cell types responsible for inducing this effect and molecular mechanisms involved remain largely undefined. One of the best examples of GVL is observed after donor lymphocyte infusions (DLI), an established therapy for relapsed disease or incipient/anticipated relapse. DLI involves infusion of peripheral blood lymphocytes from the original HSCT donor into the recipient. Sustained remission can be observed in 20-80% of patients treated with DLI depending upon the underlying disease and the intrinsic burden of targeted cells. In this review, we will discuss current knowledge about mechanisms of GVL after DLI, experimental strategies for augmenting GVL by manipulation of DLI (e.g. neoantigen vaccination, specific cell type selection/depletion) and research outlook for improving DLI and cellular immunotherapies for hematologic malignancies through better molecular definition of the GVL effect.

Effect of Early Bacillus Calmette-Guerin Vaccination of Pediatric Severe Combined Immunodeficiency Patients on the Outcome of Hematopoietic Stem Cell Transplantation Using a Reduced-Intensity Conditioning Regimen

The eminence of Bacillus Calmette-Guerin (BCG) vaccine in newborn vaccination programs has been conspicuous throughout the years, especially in low-income developing countries where tuberculosis is prevalent; however, application of the BCG vaccine is not without constraints, especially in patients afflicted with immunodeficiency diseases, such as severe combined immunodeficiency (SCID). The present study aimed to evaluate whether the administration of BCG vaccine at birth could improve the outcomes of hematopoietic stem cell transplantation (HSCT) in pediatric patients with SCID. In this study, 30 SCID patients who underwent HSCT using a reduced-intensity conditioning regimen (RIC) were followed-up for 2 years post-HSCT. The outcomes of HSCT were evaluated in both non-BCG-vaccinated patients (n = 12) and BCG-vaccinated patients (n = 18). Our results show a higher incidence of acute graft-versus-host disease (aGVHD), but not of chronic GVHD, in the BCG-vaccinated patients, and a similar overall survival (OS) rate in the 2 groups. We speculate that the similar OS rate in the 2 groups, despite the risk of BGC vaccination, was because this group received an RIC conditioning regimen. There was no other difference between the 2 groups. Considering the effect of the BCG vaccine on HSCT outcome, we suggest that the administration of BCG vaccine be deferred until age 3 months so that APT testing without the interference of maternal antibodies can be performed. However, this study could benefit from a larger cohort to further validate our findings, as the possible reason for some factors not being statistically significant was our small sample size.

Case report: HLA-haploidentical HSCT rescued with donor lymphocytes infusions in a patient with X-linked chronic granulomatous disease

Chronic granulomatous disease is an inborn error of immunity due to disrupted function of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. This results in impaired respiratory burst of phagocytes and insufficient killing of bacteria and fungi. Patients with chronic granulomatous disease are at increased risk for infections, autoinflammation and autoimmunity. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only widely available curative therapy. While HSCT from human leukocyte antigen (HLA) matched siblings or unrelated donors are standard of care, transplantation from HLA-haploidentical donors or gene therapy are considered alternative options. We describe a 14-month-old male with X-linked chronic granulomatous disease who underwent a paternal HLA-haploidentical HSCT using T-cell receptor (TCR) alpha/beta⁺/CD19⁺ depleted peripheral blood stem cells followed by mycophenolate graft versus host disease prophylaxis. Decreasing donor fraction of CD3⁺ T cells was overcome by repeated infusions of donor lymphocytes from the paternal HLA-haploidentical donor. The patient achieved normalized respiratory burst and full donor chimerism. He remained disease-free off any antibiotic prophylaxis for more than three years after HLA-haploidentical HSCT. In patients with x-linked chronic granulomatous disease without a matched donor paternal HLA-haploidentical HSCT is a treatment option worth to consider. Administration of donor lymphocytes can prevent imminent graft failure.