Alternative-Donor Hematopoietic Stem Cell Transplantation with Post-Transplantation Cyclophosphamide for Nonmalignant Disorders

Clinical considerations in the hematopoietic stem cell transplant management of primary immunodeficiencies

INTRODUCTION

Primary immunodeficiencies (PID) are genetic immune disorders causing increased predisposition to infections and autoimmunity. The only curative procedure is hematopoietic stem cell transplantation (HSCT), results from which have improved dramatically since 2000. Complications remain a serious issue, especially in HLA non-identical transplantation. In PID patients, persistent infection and autoimmunity with end-organ damage cause particular problems with approach to transplantation. This article examines these, emphasising approach to management and consequences. Areas covered: It is challenging to know which patients should be offered HSCT. As new diseases are discovered, data are required to determine natural history, and HSCT outcomes. Treatment of adults can be challenging, although HSCT outcomes are encouraging. New methods of T-lymphocyte depletion show results comparable to those of matched sibling donor transplants. New cellular therapies to treat viral infections show promising results, and immunomodulatory methods are successful in treating acute graft-versus-host disease. Expert commentary: New T-lymphocyte depletion methods are a paradigm shift in approach to HSCT for PID. In combination with new cellular approaches to treating viral infection, immunomodulatory approaches to acute graft-versus-host disease and better understanding of endothelial activation syndromes, survival approaches 90%. Widespread introduction of newborn screening for severe combined immunodeficiencies will improve survival further.

Hematopoietic cell transplantation in primary immunodeficiency - conventional and emerging indications

INTRODUCTION

Hematopoietic stem cell transplantation (HSCT) is an established curative treatment for many primary immunodeficiencies. Advances in donor selection, graft manipulation, conditioning and treatment of complications, mean that survival for many conditions is now around 90%. Next generation sequencing is identifying new immunodeficiencies, many of which are treatable with HSCT. Challenges remain however with short and long-term sequalae. This article reviews latest developments in HSCT for conventional primary immunodeficiencies and presents data on outcome for emerging diseases, Areas covered: This article reviews recently published literature detailing advances, particularly in conditioning regimens and new methods of T-lymphocyte depletion, as well as new information regarding approach and out come of transplanting patients with conventional primary immunodeficiencies. The article reviews data regarding transplant outcomes for newly described primary immunodeficiencies, particularly those associated with gain-of-function mutations. Expert commentary: New methods of graft manipulation have had significant impact on HSCT outcomes, with the range of PIDs treated using T-lymphocyte depletion significantly expanded. Outcomes for newly described diseases with variable phenotypes and clinical features, transplanted when the diagnosis was unknown are beginning to be described, and will improve as patients are identified earlier, and targeted therapies such as JAK inhibitors are used as a bridge to transplantation.

Acute graft-versus-host disease of the gut: considerations for the gastroenterologist

Haematopoietic stem cell transplantation (HSCT) is central to the management of many haematological disorders. A frequent complication of HSCT is acute graft-versus-host disease (GVHD), a condition in which immune cells from the donor attack healthy recipient tissues. The gastrointestinal system is among the most common sites affected by acute GVHD, and severe manifestations of acute GVHD of the gut portends a poor prognosis in patients after HSCT. Acute GVHD of the gastrointestinal tract presents both diagnostic and therapeutic challenges. Although the clinical manifestations are nonspecific and overlap with those of infection and drug toxicity, diagnosis is ultimately based on clinical criteria. As reliable serum biomarkers have not yet been validated outside of clinical trials, endoscopic and histopathological evaluation continue to be utilized in diagnosis. Once a diagnosis of gastrointestinal acute GVHD is established, therapy with systemic corticosteroids is typically initiated, and non-responders can be treated with a wide range of second-line therapies. In addition to treating the underlying disease, the management of complications including profuse diarrhoea, severe malnutrition and gastrointestinal bleeding is paramount. In this Review, we discuss strategies for the diagnosis and management of acute GVHD of the gastrointestinal tract as they pertain to the practising gastroenterologist.

T Cell-Depleted and T Cell-Replete HLA-Haploidentical Stem Cell Transplantation for Non-malignant Disorders

PURPOSE OF REVIEW

Hematopoietic stem cell transplantation (HSCT) is a treatment option for children with malignant and non-malignant disorders as well as an expanding number of inherited disorders. However, only a limited portion of patients in the need of an allograft have an HLA-compatible, either related or unrelated, donor. Haploidentical HSCT is now considered a valid treatment option, especially in view of the recent insights in terms of graft manipulation. This review will offer an overview of clinical results obtained through the use of haploidentical HSCT in non-malignant diseases. We will analyze major advantages and drawbacks of both T cell depleted and unmanipulated HSCT, discussing future challenges for further improving patients' outcome.

RECENT FINDINGS

T cell depletion (TCD) aims to reduce the morbidity and mortality associated with graft-versus-host disease (GvHD). However, the delayed immune recovery and the risk of graft failure still remain potential problems. In the last years, the use of post-transplant cyclophosphamide has been shown to be an alternative effective strategy to prevent GvHD in recipients of haploidentical HSCT. Recent data suggest that both T cell depleted and T cell-replete haplo-HSCT are suitable options to treat children with several types of non-malignant disorders lacking an HLA-identical donor.

Potential malignant transformation in the gastric mucosa of immunodeficient mice with persistent Mycoplasma penetrans infection

Mycoplasma infection has been reported in immunocompromised cancer patients; nevertheless, it is not clear if persistent Mycoplasma infection could facilitate the proliferation of cancer cells in immunocompromised organisms. The aim of this study was to examine the relationship between persistent Mycoplasma infection and malignant transformation in an immunodeficient host model. Immunodeficient mouse model was established using cyclophosphamide and mice gastric mucosal cells were infected with Mycoplasma penetrans (Mpe). After 18 weeks, mice were sacrificed and gastric mucosal Mpe infected cells were identified by fluorescence in situ hybridization (FISH). Moreover, pathological and ultrastructural changes in mice gastric mucosa were evaluated and the expression of multiple proto-oncogenes was examined by Western blot. Our data show that Mpe infection was detected in the blood of immunodeficient mice and Mpe persistent infection in mice gastric mucosa was confirmed by FISH. There were pathological and ultrastructural malignant transformation occurred in the gastric mucosa of infected mice compared to control mice. Mpe infected mice showed lower expression of p53 and p21 and higher H-ras expression compared to the control group. Moreover, expression of NF-κB p65 subunit increased in Mpe infected mice, similar to the TNF-α expression. Bax expression in gastric mucosa of Mpe infected mice was lower while Bcl-2 expression was higher than in the uninfected control group. Collectively these data demonstrate that persistent Mpe infection is associated with aberrant expression of multiple proto-oncogenes in gastric mucosa of immunodeficient mice which potentially facilitate the malignant transformation.

Haploidentical Related Donor Hematopoietic Stem Cell Transplantation for Dedicator-of-Cytokinesis 8 Deficiency Using Post-Transplantation Cyclophosphamide

Dedicator-of-cytokinesis 8 (DOCK8) deficiency, a primary immunodeficiency disease, can be reversed by allogeneic hematopoietic stem cell transplantation (HSCT); however, there are few reports describing the use of alternative donor sources for HSCT in DOCK8 deficiency. We describe HSCT for patients with DOCK8 deficiency who lack a matched related or unrelated donor using bone marrow from haploidentical related donors and post-transplantation cyclophosphamide (PT/Cy) for graft-versus-host disease (GVHD) prophylaxis. Seven patients with DOCK8 deficiency (median age, 20 years; range, 7 to 25 years) received a haploidentical related donor HSCT. The conditioning regimen included 2 days of low-dose cyclophosphamide, 5 days of fludarabine, 3 days of busulfan, and 200 cGy total body irradiation. GVHD prophylaxis consisted of PT/Cy 50 mg/kg/day on days +3 and +4 and tacrolimus and mycophenolate mofetil starting at day +5. The median times to neutrophil and platelet engraftment were 15 and 19 days, respectively. All patients attained >90% donor engraftment by day +30. Four subjects developed acute GVHD (1 with maximum grade 3). No patient developed chronic GVHD. With a median follow-up time of 20.6 months (range, 9.5 to 31.7 months), 6 of 7 patients are alive and disease free. Haploidentical related donor HSCT with PT/Cy represents an effective therapeutic approach for patients with DOCK8 deficiency who lack a matched related or unrelated donor.

In vivo engineering of bone tissues with hematopoietic functions and mixed chimerism

Synthetic biomimetic matrices with osteoconductivity and osteoinductivity have been developed to regenerate bone tissues. However, whether such systems harbor donor marrow in vivo and support mixed chimerism remains unknown. We devised a strategy to engineer bone tissues with a functional bone marrow (BM) compartment in vivo by using a synthetic biomaterial with spatially differing cues. Specifically, we have developed a synthetic matrix recapitulating the dual-compartment structures by modular assembly of mineralized and nonmineralized macroporous structures. Our results show that these matrices incorporated with BM cells or BM flush transplanted into recipient mice matured into functional bone displaying the cardinal features of both skeletal and hematopoietic compartments similar to native bone tissue. The hematopoietic function of bone tissues was demonstrated by its support for a higher percentage of mixed chimerism compared with i.v. injection and donor hematopoietic cell mobilization in the circulation of nonirradiated recipients. Furthermore, hematopoietic cells sorted from the engineered bone tissues reconstituted the hematopoietic system when transplanted into lethally irradiated secondary recipients. Such engineered bone tissues could potentially be used as ectopic BM surrogates for treatment of nonmalignant BM diseases and as a tool to study hematopoiesis, donor-host cell dynamics, tumor tropism, and hematopoietic cell transplantation.