CAMPATH-1M T-cell depleted BMT for SCID: long-term follow-up of 19 children treated 1987-98 in a single center

Approaches to the removal of T-lymphocytes to minimize graft-versus-host disease in patients with primary immunodeficiencies who do not have a matched sibling donor

PURPOSE OF REVIEW

Since the advent of T-lymphocyte depletion in hematopoietic stem cell transplantation (HSCT) for primary immunodeficiency, survival following this procedure has remained poor compared to results when using matched sibling or matched unrelated donors, over the last 40 years. However, three new techniques are radically altering the approach to HSCT for those with no matched donor, particularly those with primary immunodeficiencies which are not severe combined immunodeficiency.

RECENT FINDINGS

Three main techniques of T-lymphocyte depletion are altering donor choice for patients with primary immunodeficiencies and have improved transplant survival for primary immunodeficiencies to over 90%, equivalent to that for matched sibling and matched unrelated donor transplants. CD3 T cell receptor (TCR)αβ CD19 depletion, CD45RA depletion and use of posttransplant cyclophosphamide give similar overall survival of 90%, although viral reactivation remains a concern. Further modification of CD3 TCRαβ CD19 depletion by adding back inducible caspase-9 suicide gene-modified CD3 TCRαβ T-lymphocytes may further improve outcomes for patients with systemic viral infection.

SUMMARY

Over the last 5 years, the outcomes of HSCT using new T-lymphocyte depletion methods have improved to the extent that they are equivalent to outcomes of matched sibling donors and may be preferred in the absence of a fully matched sibling donor, over an unrelated donor to reduce the risk of graft versus host disease.

Long term outcomes of severe combined immunodeficiency: therapy implications

INTRODUCTION

Newborn screening has led to a better understanding of the prevalence of Severe Combined Immunodeficiency (SCID) overall and in terms of specific genotypes. Survival has improved following hematopoietic stem cell transplantation (HCT) with the best outcomes seen following use of a matched sibling donor. However, questions remain regarding the optimal alternative donor source, appropriate use of conditioning and the impact of these decisions on immune reconstitution and other late morbidities. Areas covered: The currently available literature reporting late effects after HCT for SCID and use of alternative therapies including enzyme replacement, alternative donors and gene therapy are reviewed. A literature search was performed on Pubmed and ClinicalTrials.gov using key words 'Severe Combined Immunodeficiency', 'SCID', 'hematopoietic stem cell transplant', 'conditioning', 'gene therapy', 'SCID newborn screening', 'TREC' and 'late effects'. Expert commentary: Newborn screening has dramatically changed the clinical presentation of newborn SCID. While the majority of patients with SCID survive HCT, data regarding late effects in these patients is limited and additional studies focused on genotype specific late effects are needed. Prospective studies aimed at minimizing the use of alkylating agents and reducing late effects beyond survival are needed. Gene therapy is being developed and will likely become a more commonly used treatment that will require separate consideration of survival and late effects.

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.

Current Knowledge and Priorities for Future Research in Late Effects after Hematopoietic Stem Cell Transplantation (HCT) for Severe Combined Immunodeficiency Patients: A Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric HCT

Severe combined immunodeficiency (SCID) is 1 of the most common indications for pediatric hematopoietic cell transplantation (HCT) in patients with primary immunodeficiency. Historically, SCID was diagnosed in infants who presented with opportunistic infections within the first year of life. With newborn screening (NBS) for SCID in most of the United States, the majority of infants with SCID are now diagnosed and treated in the first 3.5 months of life; however, in the rest of the world, the lack of NBS means that most infants with SCID still present with infections. The average survival for SCID patients who have undergone transplantation currently is >70% at 3 years after transplantation, although this can vary significantly based on multiple factors, including age and infection status at the time of transplantation, type of donor source utilized, manipulation of graft before transplantation, graft-versus-host disease prophylaxis, type of conditioning (if any) utilized, and underlying genotype of SCID. In at least 1 study of SCID patients who received no conditioning, long-term survival was 77% at 8.7 years (range out to 26 years) after transplantation. Although a majority of patients with SCID will engraft T cells without any conditioning therapy, depending on genotype, donor source, HLA match, and presence of circulating maternal cells, a sizable percentage of these will fail to achieve full immune reconstitution. Without conditioning, T cell reconstitution typically occurs, although not always fully, whereas B cell engraftment does not, leaving some molecular types of SCID patients with intrinsically defective B cells, in most cases, dependent on regular infusions of immunoglobulin. Because of this, many centers have used conditioning with alkylating agents including busulfan or melphalan known to open marrow niches in attempts to achieve B cell reconstitution. Thus, it is imperative that we understand the potential late effects of these agents in this patient population. There are also nonimmunologic risks associated with HCT for SCID that appear to be dependent upon the genotype of the patient. In this report, we have evaluated the published data on late effects and attempted to summarize the known risks associated with conditioning and alternative donor sources. These data, while informative, are also a clear demonstration that there is still much to be learned from the SCID population in terms of their post-HCT outcomes. This paper will summarize current findings and recommend further research in areas considered high priority. Specific guidelines regarding a recommended approach to long-term follow-up, including laboratory and clinical monitoring, will be forthcoming in a subsequent paper.

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.

Long-term clinical outcome of patients with severe combined immunodeficiency who received related donor bone marrow transplants without pretransplant chemotherapy or post-transplant GVHD prophylaxis

OBJECTIVE

To determine long-term health benefits of nonablative bone marrow transplantation for severe combined immunodeficiency (SCID), we investigated our cohort of 161 related donor bone marrow-transplanted patients with SCID. Only 16 (10%) had HLA-identical donors.

STUDY DESIGN

All 124 survivors were sent questionnaires about their current clinical statuses. Details from clinic visits were also compiled. One hundred eleven patients (90%) were reached. We compared outcomes of patients transplanted before and after 3.5 months of life and by molecular defect.

RESULTS

The overall survival rate was 77%, but the rate for the 48 infants transplanted in the first 3.5 months of life was 94%, compared with 70% for the 113 transplanted after 3.5 months (P = .002). Twenty-eight (76%) of the 37 deceased patients died of viral infections present at diagnosis. One or more clinical problems were reported to have been present in the past 2 years in 71 (64%) of the survivors, although 95 (86%) were considered healthy by their families.

CONCLUSIONS

Most patients with SCID transplanted with related donor marrow without pretransplant chemotherapy have done well in the long term, but those transplanted at <3.5 months of age had a superior survival rate, a lower rate of clinical problems, less need for booster transplants, and better nutritional status.

Long-term outcomes of nonconditioned patients with severe combined immunodeficiency transplanted with HLA-identical or haploidentical bone marrow depleted of T cells with anti-CD6 mAb

BACKGROUND

Between 1981 and 1995, 20 children with severe combined immunodeficiency (SCID; median age at transplant, 6.5 [range, 0.5-145] mo, 12 with serious infection) were treated with haploidentical T cell-depleted (anti-CD6 antibody) bone marrow (median number of 5.7 [0.8-18.8] x 10(8) nucleated cells/kg) from mismatched related donors (MMRDs), and 5 children with SCID (median age at transplant, 1.8 [0.5-5.0] mo, 1 with serious infection) were given unmanipulated bone marrow from matched related donors (MRDs). No conditioning or graft-versus-host disease (GvHD) prophylaxis was used.

OBJECTIVE

To assess the outcomes of patients with SCID who received bone marrow from MMRDs or MRDs.

METHODS

We reviewed the medical records of these 25 consecutive patients with SCID (4 with Omenn syndrome).

RESULTS

Of the 20 patients who received bone marrow from MMRDs, 12 engrafted, 10 survived at a median age of 15.2 [10.0-19.1] years, 4 had chronic GvHD (lung, intestine, skin), 5 required intravenous immunoglobulin, and 8 attended school or college. Two of 5 patients who died had chronic GvHD, and 2 developed lymphoproliferative disease. Of the 5 patients who received bone marrow from MRDs, 5 engrafted, 5 survived at a median age of 23.3 [18.5-26] years, 1 had chronic GvHD (lung, skin), 2 required intravenous immunoglobulin, and 4 attended school or college.

CONCLUSIONS

Treatment of critically ill patients with SCID with anti-CD6 antibody T cell-depleted MMRD marrow resulted in an overall 50% long-term survival of patients (83% survival of those engrafted). The principal barriers to long-term survival were delay in diagnosis, life-threatening infection, failure to engraft, and chronic GvHD. Educational goals were achieved in most of the survivors.

Mutations in CHD7 in patients with CHARGE syndrome cause T-B + natural killer cell + severe combined immune deficiency and may cause Omenn-like syndrome

More than 11 genetic causes of severe combined immunodeficiency (SCID) have been identified, affecting development and/or function of T lymphocytes, and sometimes B lymphocytes and natural killer (NK) cells. Deletion of 22q11.2 is associated with immunodeficiency, although less than 1% of cases are associated with T-B + NK + SCID phenotype. Severe immunodeficiency with CHARGE syndrome has been noted only rarely Omenn syndrome is a rare autosomal recessive form of SCID with erythroderma, hepatosplenomegaly, lymphadenopathy and alopecia. Hypomorphic recombination activating genes 1 and 2 mutations were first described in patients with Omenn syndrome. More recently, defects in Artemis, RMRP, IL7Ralpha and common gamma chain genes have been described. We describe four patients with mutations in CHD7, who had clinical features of CHARGE syndrome and who had T-B + NK + SCID (two patients) or clinical features consistent with Omenn syndrome (two patients). Immunodeficiency in patients with DiGeorge syndrome is well recognized--CHARGE syndrome should now be added to the causes of T-B + NK + SCID, and mutations in the CHD7 gene may be associated with Omenn-like syndrome.

Long-term immune reconstitution after anti-CD52-treated or anti-CD34-treated hematopoietic stem cell transplantation for severe T-lymphocyte immunodeficiency

BACKGROUND

Results of treatment of severe T-lymphocyte immunodeficiencies by means of hematopoietic stem cell (HSC) transplantation have improved. T cell-depleted haploidentical transplantations are successful if there is no HLA-identical donor. Methods to remove T lymphocytes include addition of anti-CD52 antibodies and CD34(+) HSC selection.

OBJECTIVE

Assessment of long-term immune function is important after these treatments. We looked at immune reconstitution in 36 survivors for more than 2 years after HSC transplantation for severe T-lymphocyte immunodeficiencies and compared engraftment quality between the 2 T-lymphocyte depletion methods.

METHODS

Chimerism, T- and B-lymphocyte subsets, immunoglobulin levels, and specific antibody production at last follow-up were examined. The chi(2) (Fisher exact test) and Wilcoxon rank sum analyses were used to compare the groups.

RESULTS

Nineteen patients received anti-CD52-treated and 19 anti-CD34-treated HSCs. More anti-CD52-treated patients had full donor myeloid chimerism (P = .025). All patients had full donor T-lymphocyte chimerism. There was no difference in donor B-lymphocyte chimerism, but significantly more anti-CD52-treated patients had class-switched memory B lymphocytes (P = .024), normal IgG levels, and normal responses to tetanus and Haemophilus influenzae type B vaccination. More anti-CD52-treated patients with common gamma chain or Janus-associated kinase 3 severe combined immunodeficiency had donor B lymphocytes.

CONCLUSION

Long-term T-lymphocyte function is good with either treatment method, with a low incidence of graft-versus-host disease. The results imply more incomplete donor chimerism in anti-CD34-treated patients with less B-lymphocyte function.

Cord blood in regenerative medicine: do we need immune suppression?

Cord blood is currently used as an alternative to bone marrow as a source of stem cells for hematopoietic reconstitution after ablation. It is also under intense preclinical investigation for a variety of indications ranging from stroke, to limb ischemia, to myocardial regeneration. A major drawback in the current use of cord blood is that substantial morbidity and mortality are associated with pre-transplant ablation of the recipient hematopoietic system. Here we raise the possibility that due to unique immunological properties of both the stem cell and non-stem cell components of cord blood, it may be possible to utilize allogeneic cells for regenerative applications without needing to fully compromise the recipient immune system. Issues raised will include: graft versus host potential, the immunogenicity of the cord blood graft, and the parallels between cord blood transplantation and fetal to maternal trafficking. The previous use of unmatched cord blood in absence of any immune ablation, as well as potential steps for widespread clinical implementation of allogeneic cord blood grafts will also be discussed.

Umbilical cord stem cell transplantation for primary immunodeficiencies

Primary immunodeficiencies (PIDs) are a rare but important cause of mortality and morbidity in childhood: the most severe--known as severe combined immunodeficiency (SCID)--are fatal within the first year of life; other PIDs are less immediately life-threatening, but have a poor long-term outlook. Haematopoietic stem cell transplantation (HSCT) is the best treatment for SCID and is increasingly offered for other PIDs. The best results are achieved with an HLA-matched family donor. Umbilical cord stem cells (UCSCs) are an alternative stem cell source. Results using UCSCs in the treatment of haematological disorders and malignancy are as good as those for which marrow is the stem cell source. Although PIDs make up a small proportion of disorders amenable to treatment by HSCT, UCSCs are an ideal source of haematopoietic stem cells for many of these patients. Of the 52 patients with SCID or other PIDs for whom detailed information on outcome is available, results of engraftment, immune reconstitution, incidence of graft-versus-host disease and survival are comparable with other stem cell sources. Small stem cell dose and prolonged time to viral immunity limit the patients for whom UCSCs can be used. Newer methods of achieving better engraftment, ex vivo expansion of stem cells and generation of antigen-specific cytotoxic T cells are being developed at present, and will widen the application of UCSCs as a viable source for more patients.

Single centre experience of umbilical cord stem cell transplantation for primary immunodeficiency

Primary immunodeficiencies (PID) are an important cause of childhood mortality. Haematopoietic stem cell transplantation (HSCT) is the best treatment for many PID. Umbilical cord stem cells are an alternative source of HSC. There is little data regarding outcome of umbilical cord stem cell transplantation (UCSCT) for PID. Our single centre experience is reported. A retrospective study of 14 of 148 patients transplanted for PID, who have received 15 UCSCT was performed, with specific regard to graft-versus-host disease (GvHD) and immune reconstitution. Eight patients with severe combined immunodeficiency (SCID), and six with other combined immunodeficiencies were treated. Of the patients, 12 received unrelated cords, and two had sibling transplants. Median age at transplant was 3.5 months, median nucleated cell dose was 0.8 x 10(8)/kg. All engrafted. Median time to neutrophil engraftment was 22 days, median time to platelet engraftment was 51 days. One developed significant grade III GvHD post transplantation. In total, 11 patients had full donor T and six full donor B-cell chimerism, six of nine patients >1 year post-BMT had normal IgG levels and specific antibody responses to tetanus and Hib vaccines; two are being assessed. Two patients died of multi-organ failure related to pre-existing infection and inflammatory complications respectively. UCSCT should be considered for patients requiring stem cell therapy for PID.

A novel reduced-intensity stem cell transplant regimen for nonmalignant disorders

Bone marrow transplantation (BMT) benefits nonmalignant diseases but is limited by regimen-related toxicity, graft-versus-host disease (GVHD), donor availability, and graft rejection (GR). To overcome some of these barriers, we developed a new conditioning strategy for these patients. In total, 16 patients received Campath-1H (33/48 mg; days -21 to -19), fludarabine (150 mg/m(2); days -8 to -4), melphalan (140/70 mg/m(2); day -3), and transplant using related/unrelated stem cells. GVHD prophylaxis included cyclosporine/methylprednisolone for cord cells. Other recipients also received methotrexate. Risk factors for GR included multiple transfusions (6), low stem cell numbers (1), and immunologic/metabolic disorders (3). Donor engraftment was present in 14/16 recipients. Neutrophils (ANC>0.5 x 10(9)/l) and platelets (>50 x 10(9)/l) engrafted at a median of 13 and 24 days. Two patients died of Pseudomonas sepsis prior to engraftment, one of CMV disease, and another of intracranial hemorrhage. With median follow-up of 281 days (78-907), 12/16 are stable/improved, or cured. Acute GVHD was absent (n=10) or mild and transient (grade1-2 skin) (n=4). There was no chronic GVHD. Toxicities were predominantly early infections within 100 days, and correlated with lymphopenia (CD4+ T and B cells). Stable engraftment and low incidence of significant GVHD, irrespective of age or stem cell source, make this reduced-intensity regimen attractive for nonmalignant disorders.

Thyroid dysfunction after bone marrow transplantation for primary immunodeficiency without the use of total body irradiation in conditioning

Thyroid dysfunction, a common long-term complication following bone marrow transplantation (BMT), is frequently associated with total body irradiation (TBI) given in the pre-BMT conditioning protocol. We report our preliminary observation of the prevalence of thyroid dysfunction in children transplanted for primary immunodeficiency (PID) who were given cytoreductive conditioning with busulphan and cyclophosphamide, but without TBI. We evaluated thyroid-stimulating hormone (TSH) and free thyroxine (fT4) in 83 survivors transplanted between 1987 and 2002. We found nine children (10.8%) with clinical and/or biochemical thyroid dysfunction at 4 months to 4.5 years post-BMT of which three had positive antithyroid microsomal antibodies. Two patients were classified as primary and seven as compensated hypothyroidism (hyperthyrotropinaemia). Four patients with clinical features of hypothyroidism received replacement thyroxine, while five of the seven patients with compensated hypothyroidism remain off thyroxine because we suspect this may be a transient phenomenon. Abnormalities of thyroid function including severe primary hypothyroidism may occur post-BMT in children receiving chemotherapy conditioning without TBI. Thyroid function should be assessed regularly in this group of patients.

Polysaccharide antibody responses are impaired post bone marrow transplantation for severe combined immunodeficiency, but not other primary immunodeficiencies

Established treatment of severe combined immunodeficiencies (SCID) and other primary immunodeficiencies (PID) is bone marrow transplantation (BMT). Normal lymphocyte numbers and protein antigen responses are present within 2 years of BMT, polysaccharide antibody responses appear last. Streptococcus pneumoniae infection causes significant morbidity and mortality post-BMT. Previous studies have shown good protein antigen responses post-BMT for SCID and PID, but had not examined the polysaccharide responses. We retrospectively analysed pneumococcal polysaccharide (PPS) responses in our patient series. In total, 22 SCID and 12 non-SCID PID were evaluated, all >2 years post BMT: 17 SCID, 12 PID received chemotherapy conditioning; 17 SCID, three PID had T-cell depleted (TCD) BMT, others had nonconditioned whole marrow BMT. All had normal Haemophilus influenza B and tetanus antibody responses. Of 22 SCID, 13 vs 11/12 PID responded to PPS vaccine (P=0.05). There was no association with donor age, GvHD, B-cell chimerism, or IgG2 level. Fewer TCD marrow recipients responded to PPS (P=0.04). Analysis of the SCID group showed no association of PPS response with type of marrow received. This is the first study to specifically examine PPS antibody responses following SCID and PID BMT. Pneumococcal conjugate vaccine antibody responses should be examined in these children.