Tacrolimus does not abrogate the increased risk of acute graft-versus-host disease after unrelated-donor marrow transplantation with allelic mismatching at HLA-DRB1 and HLA-DQB1

Class II HLA mismatch improves outcomes following haploidentical transplantation with posttransplant cyclophosphamide

HLA disparity is the major predictor of outcome following unrelated donor (UD) transplantation, where a single mismatch (mm) at the HLA-A, HLA-B, HLA-C, or HLA-DRB1 locus leads to increased mortality, and mismatching at multiple loci compounds this effect. In contrast, HLA disparity has not been shown to increase mortality in the context of haploidentical transplant using posttransplant cyclophosphamide (PTCy). To better define the consequences of loci-specific HLA mm, we analyzed 208 consecutive patients undergoing haploidentical transplantation for hematologic malignancy using PTCy at our institution (median age, 52 years [range, 19-75 years]; peripheral blood stem cell, 66%; reduced-intensity conditioning, 59%). Median follow-up was 65.4 months (range, 34.3-157.2 months). In univariate analysis, a single class II HLA mm at HLA-DR, HLA-DQ or a nonpermissive (np) HLA-DP mm had a protective effect on disease-free and overall survival (OS), primarily a result of reduced relapse risk. Furthermore, this survival effect was cumulative, so that patients with 3 class II mm (HLA-DR, HLA-DQ, and np HLA-DP) had the best OS. In multivariate analysis, HLA-DR mm and np HLA-DP mm were both independently associated with improved OS (hazard ratio [HR], 0.43; P =.001; and HR, 0.47; P =.011, respectively). In contrast, single or multiple mm at HLA-A, HLA-B, or HLA-C loci had no effect on acute graft-versus-host disease (GVHD), nonrelapse mortality (NRM), relapse, or survival, although the presence of an HLA-A mm was associated with increased chronic GVHD incidence. The association of class II mm with lower relapse occurred without a corresponding increase in NRM or acute or chronic GVHD. These findings will require validation in larger registry studies.

Mismatched HLA-DRB3 Can Induce a Potent Immune Response After HLA 10/10 Matched Stem Cell Transplantation

BACKGROUND

Donors for allogeneic stem cell transplantation are preferentially matched with patients for HLA-A, -B, -C, and -DRB1. Mismatches between donor and patient in these alleles are associated with an increased risk of graft-versus-host disease (GVHD). In contrast, HLA-DRB3, 4 and 5, HLA-DQ and HLA-DP are usually assumed to be low expression loci with limited relevance, although mismatches in HLA-DQ and HLA-DP can result in alloimmune responses. Mismatches in HLA-DRB3, 4, and 5 are usually not taken into account in donor selection.

METHODS

Conversion of chimerism in the presence of GVHD after CD4 donor lymphocyte infusion was observed in a patient, HLA 10/10 matched, but mismatched for HLA-DRB3 and HLA-DPB1 compared with the donor. Alloreactive CD4 T cells were isolated from peripheral blood after CD4 donor lymphocyte infusion and recognition of donor-derived target cells transduced with the mismatched patient variant HLA-DRB3 and HLA-DPB1 molecule was tested.

RESULTS

A dominant polyclonal CD4 T cell response against patient's mismatched HLA-DRB3 molecule was found in addition to an immune response against patient's mismatched HLA-DPB1 molecule. CD4 T cells specific for these HLA class II molecules recognized both hematopoietic target cells as well as GVHD target cells.

CONCLUSIONS

In contrast to the assumption that mismatches in HLA-DRB3, 4, and 5 are not of immunogenic significance after HLA 10/10 matched allogeneic stem cell transplantation, we show that in this matched setting not only mismatches in HLA-DPB1, but also mismatches in HLA-DRB3 may induce a polyclonal allo-immune response associated with conversion of chimerism and severe GVHD.

An update on the management of severe idiopathic aplastic anaemia in children

The current outlook for a child with severe idiopathic aplastic anaemia (AA) is very much better than in previous decades. In part, this may reflect better differentiation of idiopathic and inherited marrow failure. For children with idiopathic AA and a human leucocyte antigen (HLA)-matched sibling donor (MSD), allogeneic haematopoietic stem-cell transplantation (AHSCT) is the primary therapy of choice, offering long-term disease-free survival of 90%, although graft-versus-host disease remains a cause of long-term morbidity. A greater treatment challenge remains for those children without a MSD. Combination immunosuppressive therapy (IST) is associated with response rates of 70% or more. However, relapse and clonal evolution with transformation to myelodysplasia or acute myeloid leukaemia remain significant problems after IST and long-term event-free survival rates are less impressive. For children who do not have a sustained response to IST, alternate donor AHSCT should be considered. New HLA typing technologies, novel stem cell sources, reduced-intensity conditioning and graft engineering have reduced toxicity and improved the outcome after alternate donor AHSCT. Emerging therapies that capitalise on recent advances in our understanding of the pathophysiology of idiopathic AA and the immunobiology of AHSCT and IST may further improve the long-term outcome of this disease.

Recombinant interferon γ1b immune enhancement in 20 patients with hematologic malignancies and systemic opportunistic infections treated with donor granulocyte transfusions

BACKGROUND

The response to antifungal therapy alone often is suboptimal in patients with cancer who have therapy-refractory neutropenia, and even donor-derived granulocyte transfusions (GTX) are not always successful. The authors evaluated the safety and efficacy of immune enhancement using recombinant interferon gamma1b (rIFN-gamma1b) in patients with cancer who received GTX for refractory, systemic, opportunistic infections.

METHODS

Twenty recipients of high-dose donor GTX ( approximately 5.5 x 10(10) neutrophils per transfusion) who had received concurrent rIFN-gamma1b between October 2001 and December 2004 were evaluated retrospectively.

RESULTS

The median age (+/- standard deviation [SD]) was 45 +/- 17 years. Ten patients (50%) were men, 17 patients (85%) had leukemia, and 3 patients (15%) had myelodysplastic syndrome. The median +/- SD Acute Physiology and Chronic Health Evaluation II score was 15 +/- 4 (range, 7-22). Most patients (n = 18 patients; 90%) had recurrent or refractory cancer. In 6 patients (30%) who received allogeneic hematopoietic stem cell transplantation, GTX plus rIFN-gamma1b was given a median +/- SD of 26 +/- 100 days (range, 12-372 days) after transplantation. Seventeen patients (85%) had neutropenia during GTX therapy. Five patients (25%) had possible invasive fungal infection, 3 patients (15%) had probable invasive fungal infection, and 11 patients (55%) had proven invasive fungal infection. One patient (5%) had refractory Pseudomonas aeruginosa sepsis. Eight patients (40%) received corticosteroids during GTX plus rIFN-gamma1b therapy. Patients received a median +/- SD of 8 +/- 7 GTX doses (range, 4-28 doses) and 9 +/- 7 rIFN-gamma1b doses (range, 1-28 doses), for a mean +/- SD cumulative dose (CD) of 400 +/- 2621 microg. Other concomitant cytokines were granulocyte-colony stimulating factor (12 +/- 3 doses; CD, 6720 +/- 4721 microg) in 15 patients (75%) and granulocyte-macrophage-colony stimulating factor (12 +/- 9 doses; CD, 4750 +/- 4410 microg) in 14 patients (70%). Four patients (20%) developed fever, and 2 patients (10%) developed skin rashes. Reversible liver dysfunction (n = 3 patients; 15%) and tachycardia (n = 1 patients; 5%) were considered rIFN-gamma1b-associated adverse reactions; whereas, in 1 patient (5%), transient dyspnea was attributed to GTX. Four weeks after therapy started, 9 patients (45%) had complete or partial resolution of infection; and, in another 3 patients (15%), the invasive fungal infection had become stable.

CONCLUSIONS

The current results indicated that no serious adverse events were associated with rIFN-gamma1b immune enhancement in patients with systemic opportunistic infections who received donor GTX therapy.

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.

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.

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.

The safety of interferon-?-1b therapy for invasive fungal infections after hematopoietic stem cell transplantation

BACKGROUND

The restoration of normal immune responses, especially of the T-helper type 1 immune response, is an important predictor of fungal infection outcome in patients with malignant disease who undergo hematopoietic stem cell transplantation (HSCT). The authors sought to evaluate the safety of adjuvant recombinant interferon-gamma-1b as an immune-modulatory therapy HSCT recipients.

METHODS

Thirty-two patients received interferon-gamma-1b after undergoing HSCT at the author's institution between 1998 and 2003. A retrospective analysis was undertaken after obtaining permission from the Institutional Review Board.

RESULTS

Twenty-six of 32 patients (81%) received allogeneic stem cell grafts. All but 1 patient received interferon-gamma-1b and antifungals to treat infections; the other patients received interferon-gamma-1b to promote autologous graft-versus-tumor effect. Interferon-gamma-1b usually was administered at a dose of 50 mug subcutaneously every other day. The median duration (+/- standard deviation) of interferon-gamma-1b therapy was 6+/-6.5 doses (range, 1-29 doses), and the median cumulative dose was 487+/-453 mug (range, 35-2175 microg). During therapy with interferon-gamma-1b, fever was common (n=9 patients; 28%). In 1 patient (3%), new-onset lymphocytopenia occurred but resolved after cytokine therapy was discontinued; there were no interferon- gamma-1b-related episodes of neutropenia, thrombocytopenia, anemia, or liver dysfunction. Interferon-gamma-1b therapy did not precipitate or exacerbate acute or chronic graft-versus-host disease (GVHD). In fact, in 2 of 7 patients (29%) with acute GVHD and in 3 of 10 patients (30%) with chronic GVHD, significant improvements in GVHD were noted during therapy with interferon-gamma-1b. Among the 26 patients with aspergillosis, 14 patients (54%) died. However, 5 of 10 patients (50%) with presumed pulmonary aspergillosis, 3 of 9 patients (33%) with probable pulmonary aspergillosis, 1 of 2 patients (50%) with definite pulmonary aspergillosis, and 3 of 5 patients (60%) with disseminated aspergillosis responded to antifungals and adjuvant interferon-gamma-1b.

CONCLUSIONS

Recombinant interferon-gamma-1b was tolerated without serious adverse reactions in HSCT recipients. A large, prospective, randomized study will be needed to evaluate the efficacy of this cytokine in high-risk HSCT recipients who have invasive mycoses.

Tissue typing in support of unrelated hematopoietic cell transplantation

The success of unrelated hematopoietic cell transplantation (HCT) for the treatment of hematologic malignancies has closely paralleled development of robust typing methods for comprehensive and precise donor-recipient matching. The application of molecular methods in clinical research has led to a more complete understanding of the immunogenetic barriers involving host-vs-graft (HVG) and graft-vs-host (GVH) reactions. Along with the development of less toxic transplant regimens, advances in the prevention and treatment of graft-vs-host disease (GVHD) and in the supportive care of the transplant recipient, improved HLA matching of potential unrelated donors has led to clinical results that begin to compare favorably with that of HLA-identical sibling transplants.

Unrelated donor hematopoietic transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice for a range of malignant and non-malignant diseases. Unfortunately, fewer than 30% of patients have a human leukocyte antigen (HLA)-matched sibling. Advances in our understanding of the HLA system and the development of large international donor registries are supporting the increasing use of unrelated donors as an alternative source of stem cells. Unrelated donor transplantation, however, is still associated with higher complication rates than in HLA-identical sibling donor transplants. Improvements in graft-vs.-host disease prevention and treatment, new conditioning regimens and better donor selection will likely expand the indications of unrelated donor HSCT in the next decade.

Management of graft-versus-host disease

The increasing number of allogeneic stem cell transplants, particularly those involving donors other than HLA-identical siblings, has made the management of acute and chronic graft-versus-host disease (GVHD) a continuing problem for transplant experts. There have been improvements in the prevention of acute GVHD with cyclosporine- and FK506-based combination therapies, as well as lymphocyte depletion. However, fewer than 50% of patients have durable improvement after initial treatment. FK506 and mycophenolate mofetil (MMF) are promising salvage therapies in steroid-resistant GVHD, as are the anti-cytokine antibodies and the purine nucleoside analog, pentostatin. The incidence of chronic GVHD has unfortunately not decreased, despite advances in treatment of acute GVHD. Treatment of chronic GVHD involves treatment of the underlying immunologic process and supportive therapies. Initial therapy has tended to be cyclosporine and prednisone. Refractory patients have hope with combination MMF and FK506, etretinate, plaquenil, and nonpharmacologic approaches, such as PUVA. Supportive care is an integral part of chronic GVHD management with emphasis on infection control and symptom control. Death in chronic GVHD is still largely attributable to infection. The progress in therapies for GVHD has been encouraging, but the future of GVHD management lies in a better understanding of its pathogenesis.

Tacrolimus clearance is age-dependent within the pediatric population

For prevention of graft-versus-host disease, the consensus initial intravenous dose of tacrolimus for adults is 0.03 mg/kg/day. Whether target whole blood concentrations of tacrolimus in children undergoing hematopoietic stem cell transplantation can be achieved reproducibly with this dose is not known. We reviewed the tacrolimus blood levels and calculated clearances for 55 children (aged 6 months to 18 years, median 9 years) using tacrolimus after allogeneic marrow, blood stem cell or cord blood transplantation. The tacrolimus dose regimen was 0.03 mg/kg/day by continuous infusion starting on day -1 or day -2. At the first sampling in the peritransplant period, 71% of the tacrolimus blood levels were within the target range of 5-15 ng/ml, 87% were in the safe range of 5-20 ng/ml, 9% were toxic, and 4% were subtherapeutic. Twenty-five children were converted to oral drug using the recommended oral/intravenous dose ratio of 4.0. At the first sampling after oral conversion, 80% were in the target range, and 20% were subtherapeutic. Clearance of tacrolimus was calculated from the blood levels for patients during intravenous dosing and normalized by ideal body weight. There was a decreased clearance over the first 2 weeks only for the children >12 years old (P = 0.014). The initial calculated clearances of tacrolimus did not differ between age groups, but at steady state the mean tacrolimus clearance (+/- s.d.) was higher for those <6 years old (0.159+/-0.082 l/h/kg) than for those 6-12 years old (0.109+/-0.053 l/h/kg) or >12 years old (0.104 +/-0.068 l/h/kg). Children <6 years old undergoing hematopoietic stem cell transplantation have a higher weight-normalized tacrolimus clearance than older children and adults, and careful therapeutic monitoring is needed in the first 2 weeks after transplantation to avoid prolonged subtherapeutic dosing for this age group.