Impact of HLA matching on outcome of hematopoietic stem cell transplantation in children with inherited diseases: a single-center comparative analysis of genoidentical, haploidentical or unrelated donors

Perceptions and Attitudes Regarding Hematopoietic Stem Cell Donation Among Blood Donors in Riyadh, Saudi Arabia

Introduction In recent years, there has been a growing trend toward using stem cell transplantation for therapeutic purposes, making a positive impact in the medical field. Access to a compatible and willing donor is essential for those therapeutic purposes, yet the current number of registered donors remains inadequate. The present study aimed to investigate the attitude and perception of stem cell donation among blood donors in Saudi Arabia while also exploring their knowledge of hematopoietic stem cells, willingness towards donation, and fear of complications after stem cell donation. Methods A cross-sectional study was implemented to investigate the perception and attitude toward stem cell donation among blood donors in Riyadh, Saudi Arabia, through a validated self-administered questionnaire. The questionnaire comprised 35 questions divided into five sections, namely, demographics, knowledge, attitude, willingness, and fear of stem cell donation. Results The survey was distributed to 400 subjects. Out of the 400 respondents, 98.8% (n=395) were male, and 90.8% (n=363) were Saudi nationals. The majority had a high school level of education (n=259, 64.75%). Only 10.8% (n=43) of the participants were knowledgeable about stem cells. Knowledge of stem cells was highest among females aged 40-49 years, participants knowledgeable of platelet donation, and participants who donated blood more than 10 times (p-value <0.05). Participants with a bachelor's or master's degree had significantly more fear of stem cell donation complications, with a p-value of 0.003. The attitude toward stem cell donation was highly positive. Most participants strongly agreed to donate stem cells to a family member or anyone in need, 94.5% (n=378) and 62% (n=248), respectively. Conclusion Knowledge about stem cell donation among blood donors was scarce, while their willingness to donate after conversing was high. We highly recommend the initiation and establishment of educational programs to increase the knowledge of the public and, specifically, blood donors.

What compatibility in 2017 for the haematopoietic stem cell transplantation?

The diversification of potential donors to perform stem cell allografts now enables to propose a compatible graft cell source adapted to the different clinical situations. Transplants with a geno-identical sibling donor, otherwise with the most HLA-compatible unrelated donor, remain the first-line solutions. Alternative transplants allow to graft patients having no donors in international registries, owing to the rarity of their HLA typing. They are carried out with fairly incompatible grafts and are therefore limited by the existence in the recipient of preformed anti-HLA antibodies which predispose to their rejection. The simple prevention of acute Graft-versus-host disease in haplo-identical transplants, as well as the availability of donors, explain why they have very often replaced placental stem cell transplants. These latter remain useful for pediatric patients or in the absence of family donors.

Umbilical Cord Blood: Counselling, Collection, and Banking

OBJECTIVE

To review current evidence regarding umbilical cord blood counselling, collection, and banking and to provide guidelines for Canadian health care professionals regarding patient education, informed consent, procedural aspects, and options for cord blood banking in Canada.

OPTIONS

Selective or routine collection and banking of umbilical cord blood for future stem cell transplantation for autologous (self) or allogeneic (related or unrelated) treatment of malignant and non-malignant disorders in children and adults. Cord blood can be collected using in utero or ex utero techniques.

OUTCOMES

Umbilical cord blood counselling, collection, and banking, education of health care professionals, indications for cord blood collection, short- and long-term risk and benefits, maternal and perinatal morbidity, parental satisfaction, and health care costs.

EVIDENCE

Published literature was retrieved through searches of Medline and PubMed beginning in September 2013 using appropriate controlled MeSH vocabulary (fetal blood, pregnancy, transplantation, ethics) and key words (umbilical cord blood, banking, collection, pregnancy, transplantation, ethics, public, private). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials. Searches were updated on a regular basis and incorporated in the guideline to September 2014. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, and national and international medical specialty societies.

VALUES

The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

Umbilical cord blood is a readily available source of hematopoetic stem cells used with increasing frequency as an alternative to bone marrow or peripheral stem cell transplantation to treat malignant and non-malignant conditions in children and adults. There is minimal harm to the mother or newborn provided that priority is given to maternal/newborn safety during childbirth management. Recipients of umbilical cord stem cells may experience graft-versus-host disease, transfer of infection or genetic abnormalities, or therapeutic failure. The financial burden on the health system for public cord blood banking and on families for private cord blood banking is considerable. Recommendations 1. Health care professionals should be well-informed about cord blood collection and storage and about factors that influence the volume, quality, and ability to collect a cord blood unit. (III-A) 2. Health care professionals caring for women and families who choose private umbilical cord blood banking must disclose any financial interests or potential conflicts of interest. (III-A) 3. Pregnant women should be provided with unbiased information about umbilical cord blood banking options, including the benefits and limitations of public and private banks. (III-A) 4. Health care professionals should obtain consent from mothers for the collection of umbilical cord blood prior to the onset of active labour, ideally during the third trimester, with ample time to address any questions. (III-A) 5. Health care professionals must be trained in standardized procedures (ex utero and in utero techniques) for cord blood collection to ensure the sterility and quality of the collected unit. (II-2A) 6. Umbilical cord blood should be collected with the goal of maximizing the content of hematopoietic progenitors through the volume collected. The decision to bank the unit will depend upon specific measures of graft potency. (II-2A) 7. Umbilical cord blood collection must not adversely affect the health of the mother or newborn. Cord blood collection should not interfere with delayed cord clamping. (III-E) 8. Health care professionals should inform pregnant women and their partners of the benefits of delayed cord clamping and of its impact on cord blood collection and banking. (II-2A) 9. Cord blood units collected for public or private banking can be used for biomedical research, provided consent is obtained, when units cannot be banked or when consent for banking is withdrawn. (II-3B) 10. Mothers may be approached to donate cells for biomedical research. Informed consent for research using cord blood should ideally be obtained prior to the onset of active labour or elective Caesarean section following established research ethics guidelines. (II-2A).

Risk Factors for Acute and Chronic Graft-versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation with Umbilical Cord Blood and Matched Sibling Donors

Allogeneic hematopoietic cell transplantation is often complicated by graft-versus-host disease (GVHD). We analyzed the incidences and risk factors for acute (aGVHD) and chronic GVHD (cGVHD), and their impact on disease relapse and survival, among recipients of single umbilical cord blood (sUCB, n = 295), double umbilical cord blood (dUCB, n = 416), and matched sibling donor (MSD, n = 469) allografts. The incidences of grades II to IV aGVHD and chronic GVHD among dUCB, sUCB, and MSD were 56% and 26%, 26% and 7%, 37% and 40%, respectively. Development of aGVHD had no effect on relapse, nonrelapse mortality, or overall survival among cord blood recipients, but it was associated with worse nonrelapse mortality and survival in MSD recipients. Development of cGVHD was only associated with lower relapse in dUCBT. In multivariate analysis of GVHD incidence, age > 18 years was associated with higher incidence of aGVHD and cGVHD across all cohorts. In both UCB cohorts worse HLA match and prior aGVHD were associated with higher risks of aGVHD and cGVHD, respectively. Nonmyeloablative conditioning limited the risk of aGVHD compared with myeloablative conditioning in dUCB recipients. Cyclosporine A and mycophenolate mofetil as GVHD prophylaxis lowered the risk of cGVHD, compared with steroids with cyclosporine A, among sUCB recipients. This large contemporary analysis suggests distiinct risks and consequences of GVHD for UCB and MSD recipients. Limiting the severity of aGVHD remains important in all groups. Increasing the cord blood inventory or developing strategies that reduce the cell-dose threshold and thereby increase the chance of identifying an adequately dosed, better HLA-matched sUCB unit may further limit risks of aGVHD after UCB transplantation.

Analysis of 120 pediatric patients with nonmalignant disorders transplanted using unrelated plasma-depleted or -reduced cord blood

BACKGROUND

Unrelated cord blood (CB) is an important stem cell source for unrelated hematopoietic cell transplantation (HCT) of patients with nonmalignant disorders. Processing methods to prepare red blood cell-reduced CB units incur significant nucleated cell loss. In contrast, plasma depletion or reduction (PDR) processing of CB units entails the removal of only a portion of the plasma with minimal nucleated cell loss. However, there are relatively limited data regarding outcomes of CB transplants using units processed by PDR.

STUDY DESIGN AND METHODS

A Center for International Blood and Marrow Transplant Research (CIBMTR)-audited analysis was performed on 120 pediatric patients with nonmalignant disorders transplanted between November 2001 and January 2008 at 29 US and 17 international centers using PDR CB units from two CB banks.

RESULTS

Transplant characteristics were as follows: median age, 3.5 years (range, 0.1-14 years); median patient weight, 15 kg (range, 4-61 kg); 58% male; HLA matches (intermediate-resolution HLA-A and HLA-B and high-resolution HLA-DRB1) of the units used in these patients six of six in 26, five of six in 48, four of six in 47, and three of six or two of six in 6; median prefreeze total nucleated cell dose, 10.5×10(7)/kg; median prefreeze CD34+ dose, 3.7×10(5)/kg; and nonmyeloablative regimen in 24%. The median times to myeloid and platelet engraftment were 21 and 49 days, respectively. The cumulative incidence of reported Grade II to IV acute graft-versus-host disease (aGVHD) was 38±5%, and 19±4% had Grade III to IV aGVHD. The Kaplan-Meier estimates of 3-year transplant-related mortality, overall survival, and disease-free survival were 20±4, 79±4, and 70±6%, respectively.

CONCLUSION

These data demonstrate the effectiveness of PDR CB units for HCT.

Hematopoietic stem cell transplantation for CD3δ deficiency

BACKGROUND

CD3δ deficiency is a fatal form of severe combined immunodeficiency that can be cured by hematopoietic stem cell transplantation (HSCT). The presence of a thymus loaded with T-cell progenitors in patients with CD3δ deficiency may require special considerations in choosing the regimen of conditioning and the type of HSCT.

OBJECTIVES

To study the outcome of CD3δ deficiency by using various modalities of stem cell transplantation.

METHODS

We analyzed data on 13 patients with CD3δ deficiency who underwent HSCT in 7 centers. HSCT was performed by using different sources of donor stem cells as well as various conditioning regimens.

RESULTS

One patient received stem cells from a matched related donor and survived after a second transplant, needing substantial conditioning in order to engraft. Only 2 of 7 other patients who received a mismatched related donor transplant survived; 2 of them had no conditioning, whereas the others received various combinations of conditioning regimens. Engraftment of T cells in the survivors appears incomplete. Three other patients who received stem cells from a matched unrelated donor survived and enjoyed full immune reconstitution. Two patients received unrelated cord blood without conditioning. One of them has had a partial but stable engraftment, whereas the other engrafted well but is only 12 months after HSCT. We also report here for the first time that patients with CD3δ deficiency can present with typical features of Omenn syndrome.

CONCLUSIONS

HSCT is a successful treatment for patients with CD3δ deficiency. The small number of patients in this report prevents definitive statements on the importance of survival factors, but several are suggested: (1) HLA-matched donor transplants are associated with superior reconstitution and survival than are mismatched donor transplants; (2) substantial conditioning appears necessary; and (3) early diagnosis and absence of opportunistic infections may affect outcome.

Bone marrow transplantation using HLA-matched unrelated donors for patients suffering from severe combined immunodeficiency

Severe combined immunodeficiency (SCID) is fatal in infancy unless corrected with allogeneic bone marrow transplants (BMT), preferably from a family-related genotypically HLA-identical donor (RID) or phenotypically HLA-matched family donor (PMD). For the majority of SCID patients, such donors are not available; Therefore, parents who are HLA-haploidentical donors (HID) or HLA-matched unrelated donors (MUD) have been used. MUD BMT are associated with increased frequency of acute graft versus host disease, which can be controlled by high doses of steroids. HID BMT are associated with increased frequency of short- and long-term graft failure, need for repeated transplants, fatal pneumonitis, impaired immune reconstitution, and long-term complications, contributing to lower survival. In conclusion, the excellent long-term survival, immune reconstitution, and normal quality of life after MUD BMT suggests that in the absence of RID or PMD, MUD BMT should be offered for patients suffering from SCID.

Hematopoietic stem cell transplantation for profound T-cell deficiency (combined immunodeficiency)

Typical cases of severe combined immunodeficiency present at infancy (most frequently at 6 months of age) with repeated opportunistic infections; failure to thrive; and scarcity of lymphoid tissues, including undetectable lymph nodes and a small dysplastic thymus. Patients with profound T-cell dysfunction (PTD)/combined immunodeficiency (CID) have moderate to large numbers of circulating autologous lymphocytes with variable residual function. These cells may interfere with proper engraftment and may complicate the procedure of HSCT, hence the need for conditioning. There is no immediate explanation for the excellent outcome of hematopoietic stem cell transplantation (HSCT) for PTD/CID. Historically, protocols for mismatched related donor HSCT did not include conditioning regimens, which could jeopardize engraftment. Careful studies on the role of conditioning, especially myeloablative conditioning, should be conducted in the future. It is possible that in some genotypes, related identical donor can be accepted by the recipient with little or no conditioning. Until such studies become instructive, the protocols in current use seem to provide excellent, although not perfect, outcome in patients with PTD/CID.

Allogeneic haemopoietic stem cell transplantation in children: what alternative donor should we choose when no matched sibling is available?

Allogeneic haemopoietic stem cell transplantation has provided curative therapy for life-threatening malignant and non-malignant diseases in children for over 40 years. Only 25% of children in whom an allograft is indicated have the ideal option of a human leucocyte antigen-identical sibling donor. Substantial advances in the use of alternative donors (unrelated volunteer donors, haploidentical family donors and unrelated umbilical cord blood donors) now make it possible for almost all children to benefit from this life-saving treatment. Each donor choice is associated with distinct advantages and disadvantages, which have greater or lesser importance in different diseases. We review the current status of alternative donor transplantation for haematological malignancies, primary immunodeficiencies, inherited metabolic disorders and bone marrow failure syndromes and outline the current UK consensus donor selection algorithms for these disease groups.

Principles and analysis of hematopoietic stem cell transplantation outcomes: the physician's perspective

Hematopoietic stem cell transplantation (HSCT) is used widely for the treatment of malignant and non-malignant diseases. Advances in transplantation strategies such as modifications to existing transplant-conditioning regimens to lower morbidity and mortality, use of alternative donors and grafts, supportive care including graft-versus-host disease prophylaxis and antimicrobial therapy have led to increasing numbers of HSCT being performed. The procedure is now available to children, young and older adults with an ever increasing number of survivors from this procedure. Analysis of outcomes after HSCT giving consideration to existing strategies warrants using appropriate statistical methodology. This is critical not only in documenting the current success of HSCT but to plan future strategies to optimize accessibility to HSCT, donor and graft choices, patient selection, counsel potential HSCT candidates and long-term survivors and plan intervention trials for these persons. We describe concepts and principles of HSCT to better understand the complexities associated with outcome analysis.

G-CSF-mobilized haploidentical peripheral blood stem cell transplantation in children with poor prognostic nonmalignant disorders

Haploidentical hematopoietic stem cell transplantation (HSCT) is currently one of the alternative curative treatment options for some nonmalignant but also for malignant diseases. However, concerns regarding its safety cause delays in time and a successful outcome. Between 2000 and 2005, twenty-one children with poor prognostic nonmalignant disorders, 13 boys and 8 girls, with a median age of 12 months, underwent 28 haploidentical peripheral HSCT. Immunomagnetic bead depletion device (CliniMACS) was used for indirect T-cell depletion. Indications for transplant were severe combined immunodeficiency (n=16), osteopetrosis (n=2), MDS (n=1), amegakaryocytic thrombocytopenia (n=1), and aplastic anemia (n=1). Five patients (24%) had lung infection at the time of transplantation. The patients received a median of 25.67 x 10(6) G-CSF-mobilized peripheral CD34(+) progenitor cells and a median of 4.19 x 10(4) T-lymphocytes per kilogram of body weight with a T-cell depletion rate of median 4.59 logs. The rate of total engraftment was 66.6%. Median times for leukocyte and platelet engraftment were 14 and 16 days, respectively. The 6-year projected survival was 32% for all patients and 29.76% for patients with severe combined immunodeficiency (SCID). The rates of transplant-related mortality, graft failure, and severe GvHD were 14.2, 33.4%, and 8.3%, respectively. Infection was the main cause of death. The poor outcome may be explained with the poor prognostic factors of our patients such as the type of SCID in most cases (T-B- SCID), the median age over 6 months and the presence of lung infection in some children at the time of transplantation.

Gene therapy for severe combined immunodeficiency: are we there yet?

Inherited and acquired diseases of the hematopoietic system can be cured by allogeneic hematopoietic stem cell transplantation. This treatment strategy is highly successful when an HLA-matched sibling donor is available, but if not, few therapeutic options exist. Gene-modified, autologous bone marrow transplantation can circumvent the severe immunological complications that occur when a related HLA-mismatched donor is used and thus represents an attractive alternative. In this review, we summarize the advantages and limitations associated with the use of gene therapy to cure SCID. Insertional mutagenesis and technological improvements aimed at increasing the safety of this strategy are also discussed.

Risk assessment in haematopoietic stem cell transplantation: histocompatibility

Consideration of potential donors for transplantation includes a rigorous assessment of the availability and HLA-match status of family members, and the identification of suitable unrelated donors when related donors are not available. Because HLA gene products provoke host-versus-graft and graft-versus-host alloimmune responses, HLA matching serves a critical preventive role in lowering risks of graft failure and graft-versus-host disease (GVHD). At the same time, graft-versus-leukemia effects associated with HLA mismatching may provide an immunological means to lower the recurrence of post-transplant disease in high-risk patients. The definition of a suitable allogeneic donor is ever changing, shaped not only by current typing technology for the known HLA genes but also by the specific transplant procedure. Increased safety of alternative donor hematopoietic cell transplantation (HCT) has been achieved in part through advances in the field of immunogenetics. Increased availability of HCT through the use of HLA-mismatched related and unrelated donors is feasible with a more complete understanding of permissible HLA mismatches and the role of NK-KIR genes in transplantation.

Genetics of Risk Factors for Graft-Versus-Host Disease

Modern understanding of the genetic basis of graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation (HSCT) involves knowledge of human leukocyte antigen (HLA), killer immunoglobulin-like receptors (KIR), cytokine genes, and their interactions. Insights into the immunogenetic basis of GVHD come from long-standing clinical experience in the use of myeloablative conditioning regimens and donor bone marrow as the grafting source. Under these circumstances, donor T-cell recognition of host HLA can cause GVHD. The recent elucidation of HLA class I as ligands for natural killer (NK) cell inhibitory KIR demonstrates that GVHD is the result of a complex interplay between the innate and adaptive immune responses. The extent to which T cells and NK cells contribute to clinical GVHD is a function of the host post-conditioning environment, immunosuppressive treatments, and the content of the graft source. The contribution of donor and host genetic differences in cytokine genes in modulating risks of GVHD has recently been recognized.

Pediatric hemophagocytic syndromes: a diagnostic and therapeutic challenge

Pediatric hemophagocytic syndrome (HS) is a severe and often fatal clinical disorder. This syndrome is frequently unrecognized, and thus, affected children may receive suboptimal management, leading to an increase in mortality. The purpose of this review is to provide a clinical guide to (1) the recognition of HS based on clinical, biologic, and pathologic features; (2) the identification of the primary cause of HS in a given affected child; and (3) the initiation of effective treatment in a timely manner.

Rescue of ATPa3-deficient murine malignant osteopetrosis by hematopoietic stem cell transplantation in utero

Autosomal recessive osteopetrosis (ARO) is a paradigm for genetic diseases that cause severe, often irreversible, defects before birth. In ARO, osteoclasts cannot remove mineralized cartilage, bone marrow is severely reduced, and bone cannot be remodeled for growth. More than 50% of the patients show defects in the osteoclastic vacuolar-proton-pump subunit, ATP6a3. We treated ATP6a3-deficient mice by in utero heterologous hematopoietic stem cell (HSC) transplant from outbred GFP transgenic mice. Dramatic phenotype rescue by GFP osteoclasts was obtained with engraftment, which was observed in most cases. Engraftment survived for variable periods. Recipients were not immunosuppressed, and graft-versus-host disease was not observed in all pups born after in utero treatment. Thus, differentiation of unmatched HSC transplanted in utero is sufficient to prevent fatal defects in ARO and may prevent complications of ARO unresponsive to conventional bone marrow transplantation. The presence of defective cells is not a barrier to the rescue of the phenotype by donor HSC.

Human leukocyte antigen matching in unrelated donor hematopoietic cell transplantation

Hematopoietic cell transplantation (HCT) from unrelated donors is a curative therapy for many malignant and nonmalignant blood disorders. The success of unrelated HCT is influenced by the degree of human leukocyte antigen (HLA) compatibility between the donor and patient. When donor matching for HLA alleles is feasible, overall transplant outcome is superior. The presence of donor-recipient mismatching is associated with increased risk of post-transplant complications including graft rejection, acute and chronic graft-versus-host disease (GVHD), and mortality; these risks are increased with multiple HLA mismatches. For the majority of patients who lack HLA-matched unrelated donors, current research is focused on the identification of permissible HLA mismatches. The influence of nongenetic factors on the tolerability of HLA mismatching has recently become evident, demonstrating a need for the integration of both genetic and nongenetic variables in donor selection.

Listing of Common HLA Alleles and Haplotypes Based on the Study of 356 Families Residing in the Paris, France, Area: Implications for Unrelated Hematopoietic Stem Cell Donor Selection

In this study we have identified frequent human leukocyte antigen (HLA)-A, -B, -C,-DRB1, and -DQB1 alleles, frequent HLA-B/C, HLA-DRB1/DQB1 two-allele associations, and the most common HLA-A/B/C/DRB1/DQB1 five-locus haplotypes in a population residing in the Paris, France, area. The study was carried out in 356 families of children awaiting hematopoietic stem-cell transplantation (HSCT), with the selection criterion that haplotypes could be assigned with certainty to both the patient and at least one parent. Parental haplotypes were HLA-A, -B serologically typed, and HLA-C, -DRB1, -DQB1 broadly typed by polymerase chain reaction-sequence-specific oligonucleotide probe. The alleles of the most frequent haplotypes were subsequently defined at a high-resolution level by polymerase chain reaction-sequence-specific primer. The results on the distribution of common alleles and common allele associations demonstrated similarities with the previously published data in Caucasian populations, as expected from the geographic origin of the studied population. More importantly, this study provides the largest listing of common B/C and DRB1/DQB1 associations and of common five-allele haplotypes defined with certainty in a Caucasian population to date. These results can be used to help estimate the likelihood of finding a suitable donor in unrelated HSCT and to delineate search strategies for potential donors.

HLA matching in allogeneic stem cell transplantation

PURPOSE OF REVIEW

The success of unrelated hematopoietic cell transplantation (HCT) is influenced by the degree of HLA compatibility between the donor and patient. The goal of this review is to summarize new findings in the field of immunogenetics and HCT from unrelated donors using myeloablative conditioning regimens.

RECENT FINDINGS

Molecular typing methods can discriminate unique alleles encoded by HLA class I and II genes. Incompatibility of donor-recipient HLA alleles increases posttransplant complications including graft rejection, acute and chronic graft-versus-host disease, and mortality. These posttransplant risks increase with increasing numbers of HLA mismatches. The identification of permissible HLA mismatches may be aided by the use of functional assays. Nongenetic factors, including the stage of disease at the time of transplantation, may influence the effect of HLA mismatching on survival.

SUMMARY

HLA alleles are functionally relevant. Unrelated HCT can be optimized by comprehensive and precise donor-recipient allele matching. For patients with high-risk diseases who lack matched donors, use of donors with a single HLA mismatch may permit early treatment before disease progression.