Anti-interleukin-2 receptor antibodies for the prevention of rejection in pediatric renal transplant patients: current status

Therapy in the Course of Kidney Graft Rejection-Implications for the Cardiovascular System-A Systematic Review

Kidney graft failure is not a homogenous disease and the Banff classification distinguishes several types of graft rejection. The maintenance of a transplant and the treatment of its failure require specific medications and differ due to the underlying molecular mechanism. As a consequence, patients suffering from different rejection types will experience distinct side-effects upon therapy. The review is focused on comparing treatment regimens as well as presenting the latest insights into innovative therapeutic approaches in patients with an ongoing active ABMR, chronic active ABMR, chronic ABMR, acute TCMR, chronic active TCMR, borderline and mixed rejection. Furthermore, the profile of cardiovascular adverse effects in relation to the applied therapy was subjected to scrutiny. Lastly, a detailed assessment and comparison of different approaches were conducted in order to identify those that are the most and least detrimental for patients suffering from kidney graft failure.

Therapeutic and Prophylactic Use of Oral, Low-Dose IFNs in Species of Veterinary Interest: Back to the Future

Cytokines are important molecules that orchestrate the immune response. Given their role, cytokines have been explored as drugs in immunotherapy in the fight against different pathological conditions such as bacterial and viral infections, autoimmune diseases, transplantation and cancer. One of the problems related to their administration consists in the definition of the correct dose to avoid severe side effects. In the 70s and 80s different studies demonstrated the efficacy of cytokines in veterinary medicine, but soon the investigations were abandoned in favor of more profitable drugs such as antibiotics. Recently, the World Health Organization has deeply discouraged the use of antibiotics in order to reduce the spread of multi-drug resistant microorganisms. In this respect, the use of cytokines to prevent or ameliorate infectious diseases has been highlighted, and several studies show the potential of their use in therapy and prophylaxis also in the veterinary field. In this review we aim to review the principles of cytokine treatments, mainly IFNs, and to update the experiences encountered in animals.

Genetic barriers in transplantation medicine

The successful of transplantation is determined by the shared human leukocyte antigens (HLAs) and ABO blood group antigens between donor and recipient. In recent years, killer cell receptor [i.e., killer cell immunoglobulin-like receptor (KIR)] and major histocompatibility complex (MHC) class I chain-related gene molecule (i.e., MICA) were also reported as important determinants of transplant compatibility. At present, several different genotyping techniques (e.g., sequence specific primer and sequence based typing) can be used to characterize blood group, HLA, MICA and KIR and loci. These molecular techniques have several advantages because they do not depend on the availability of anti-sera, cellular expression and have greater specificity and accuracy compared with the antibody-antigen based typing. Nonetheless, these molecular techniques have limited capability to capture increasing number of markers which have been demonstrated to determine donor and recipient compatibility. It is now possible to genotype multiple markers and to the extent of a complete sequencing of the human genome using next generation sequencer (NGS). This high throughput genotyping platform has been tested for HLA, and it is expected that NGS will be used to simultaneously genotype a large number of clinically relevant transplantation genes in near future. This is not far from reality due to the bioinformatics support given by the immunogenetics community and the rigorous improvement in NGS methodology. In addition, new developments in immune tolerance based therapy, donor recruitment strategies and bioengineering are expected to provide significant advances in the field of transplantation medicine.

Management of immunosuppressant agents following liver transplantation: Less is more

Immunosuppression in organ transplantation was revolutionary for its time, but technological and population changes cast new light on its use. First, metabolic syndrome (MS) is increasing as a public health issue, concomitantly increasing as an issue for post-orthotopic liver transplantation patients; yet the medications regularly used for immunosuppression contribute to dysfunctional metabolism. Current mainstay immunosuppression involves the use of calcineurin inhibitors; these are potent, but nonspecifically disrupt intracellular signaling in such a way as to exacerbate the impact of MS on the liver. Second, the impacts of acute cellular rejection and malignancy are reviewed in terms of their severity and possible interactions with immunosuppressive medications. Finally, immunosuppressive agents must be considered in terms of new developments in hepatitis C virus treatment, which undercut what used to be inevitable viral recurrence. Overall, while traditional immunosuppressive agents remain the most used, the specific side-effect profiles of all immunosuppressants must be weighed in light of the individual patient.

Basiliximab: efficacy and safety evaluation in kidney transplantation

INTRODUCTION

Basiliximab is a chimeric monoclonal antibody directed against the alpha chain of interleukin-2 receptor (IL-2R). When administered intravenously at a dosage of 20 mg at the time of transplantation and 4 days later, basiliximab saturates the alpha chain of IL-2R for 4 weeks.

AREAS COVERED

This review evaluates the efficacy and safety of basiliximab in kidney transplantation. Randomized controlled trials showed that basiliximab can significantly reduce the incidence of acute rejection without increasing the risk of adverse events. When compared with other antibodies used for induction, basiliximab showed efficacy and safety profiles similar to daclizumab, another monoclonal antibody directed against the alpha chain of IL-2R. In comparison with rabbit anti-thymocyte globulins (rATG), basiliximab showed a similar efficacy. However, in patients at higher risk of rejection, rATG proved to be more effective. No serious safety problems related to basiliximab have been reported.

EXPERT OPINION

There is a solid evidence that basiliximab can significantly decrease the risk of acute rejection in kidney transplant recipients without increasing adverse events. This can allow decreased dosage or avoidance of glucocorticoids and reduced dosage of calcineurin inhibitors. On the basis of efficacy, tolerability, ease of administration, and cost effectiveness, basiliximab may be considered the drug of choice for the prophylaxis of acute rejection in standard renal transplant recipients.

The role of basiliximab in the evolving renal transplantation immunosuppression protocol

Basiliximab is a chimeric mouse-human monoclonal antibody directed against the alpha chain of the interleukin-2 (IL-2) receptor on activated T lymphocytes. It was shown in phase III trials to reduce the number and severity of acute rejection episodes in the first year following renal transplantation in adults and children, with a reasonable cost-benefit ratio. The drug does not increase the incidence of opportunistic infections or malignancies above baseline in patients treated with conventional calcineurin inhibitor-based immunosuppression. In the field of renal transplantation, basiliximab does not increase kidney or patient survival, despite the reduction in the number of rejection episodes. Basiliximab may reduce the incidence of delayed graft function. In comparison with lymphocyte-depleting antibodies basiliximab appears to have equal efficacy in standard immunological risk patients. Recently, IL-2 receptor monoclonal antibodies have been used with the objective of reducing or eliminating the more toxic elements of the standard immunosuppression protocol. Several trials have incorporated basiliximab in protocols designed to avoid or withdraw rapidly corticosteroids, as well as protocols which substitute target-of-rapamycin (TOR) inhibitors for calcineurin inhibitors.

Systemic monoclonal antibody therapy (daclizumab) in the treatment of cicatrizing conjunctivitis in stevens-johnson syndrome, refractory to conventional therapy

PURPOSE

At least one-year follow-up of a case series of young Stevens-Johnson syndrome (SJS) patients with cicatrizing ocular surface disease and recurrent inflammation (SJS-RI) treated with systemic humanized monoclonal antibody (daclizumab).

METHODS

Five patients (median age 16 yr; range 8-34 yr) with SJS, with recurrent inflammation refractory to conventional immunotherapy, were enrolled in a prospective non-randomized case series study. Inclusion criteria were patients with SJS and ocular cicatrizing inflammatory disease with severe visual impairment, using topical or systemic anti-inflammatory and/or immunomodulatory drugs without clinical improvement resulting in persistent inflammation (SJS-RI). Treatment with Daclizumab 1 mg/Kg (intravenous) was scheduled in three cycles. First cycle with concomitant immunotherapy: a total of 5 doses, with 14 days interval between them (total of this cycle: 10 weeks). Second cycle: interval was increased to 3 weeks; the patients received 2 doses (the second cycle had a total of 6 weeks). Third cycle: maintenance phase with 4 weeks interval between each application, until at least 12 months of the total follow up. After the first cycle (5th dose), the patients were kept with preservative-free lubricants and systemic doxycycline.

RESULTS

Control of ocular inflammation was observed at a median of 8 weeks (range 6-10 weeks) in all patients, with relapses in two patients at 20-36 weeks. Relapses were controlled with topical steroids at a median of 10 days, and within 2 weeks the steroids were tapered for both patients.

CONCLUSION

In this small case series, daclizumab demonstrated to play a beneficial role in the control of the inflammatory process of the recurrent inflammation in SJS, refractory to conventional immunomodulatory therapy.

Monoclonal antibody-induced cytokine-release syndrome

Monoclonal antibodies (mAbs) are widely used in anti-inflammatory and tumor therapy. Although effective, mAbs can cause a variety of adverse effects. An important toxicity seen with a few mAbs is cytokine-release syndrome (CRS). These mAbs include: alemtuzumab, muromonab-CD3, rituximab, tosituzumab, CP-870,893, LO-CD2a/BTI-322 and TGN1412. By contrast, over 30 mAbs used clinically are not associated with CRS. In this review, the clinical aspects of CRS, the mAbs associated with CRS, the cytokines involved and putative mechanisms mediating cytokine release will be discussed. This will be followed by a discussion of the poor predictive value of studies in animals and the prospects for creating in vitro screens. Finally, approaches to decreasing the probability of CRS, decreasing the severity or treating CRS, should it occur, will be described.

Extended daclizumab monotherapy for rejection-free survival in non-adherent adolescent recipients of renal allografts

Acute rejection episodes are almost inevitable in the face of immunosuppression non-adherence and a known risk factor for developing chronic allograft nephropathy and accelerated graft loss. Daclizumab, a humanized monoclonal antibody directed against the alpha chain of the IL-2 receptor, is an important advance for induction therapy in renal transplant immunosuppression, reducing early acute graft rejection without affecting the tolerability of standard immunosuppression, for both steroid-based and steroid-free immunosuppressive protocols, in children and adults. In the absence of depot immunosuppression for maintenance therapy, we explored extended daclizumab therapy as temporary maintenance immunosuppression for acute rejection prophylaxis in two patients with recalcitrant immunosuppression non-adherence. Both patients had prior episodes of aggressive acute rejection associated with their non-adherence but achieved stable and rejection-free renal allograft function with daclizumab monotherapy in the presence of documented non-adherence thus providing an effective bridge for up to 12 months until immunosuppression adherence was re-established with ongoing psychosocial support. This report suggests that daclizumab monotherapy over an extended period of time during the period of non-adherence in the post transplant period could be a rescue modality to avoid immune activation and thereby prevent acute rejection in the face of erratic maintenance immunosuppression.

Remission of refractory minimal change nephrotic syndrome after basiliximab therapy

Minimal change nephrotic syndrome has been proposed to be a disorder of T cell dysfunction. It is hypothesized that a circulating factor(s) from activated T cells might alter glomerular permeability to protein. Some studies have provided evidence that up-regulation of interleukin-2 may be involved, not only in the pathophysiology of minimal change nephrotic syndrome, but also in steroid resistance. Basiliximab, an anti-interleukin-2 receptor antibody, is indicated for the prophylaxis of acute organ rejection in adults and children with kidney transplants. Clinical trials have shown that basiliximab is effective and well tolerated. We describe here a pediatric patient who continuously had massive proteinuria and hypoalbuminemia for 5 years, despite pulse therapy with methylprednisolone and cyclophosphamide and prolonged oral treatment with cyclosporine and mizoribine. He had experienced several disease- and treatment-associated complications, such as bacterial infections, indirect inguinal hernias, and cataracts. After he had been given a single dose of basiliximab, he achieved complete remission of proteinuria and then discontinued all immunosuppressant treatment.

Two-dose daclizumab induction in pediatric renal transplantation

DCZ, an IL-2 receptor antagonist, has been widely used for induction therapy in pediatric and adult solid organ transplantation. Originally, it was recommended as a five-dose regimen; however, fewer doses may be efficacious and less costly for prevention of rejection. There is limited experience with the use of fewer doses in pediatric renal transplantation. We retrospectively reviewed the outcomes of 26 primary pediatric renal transplants performed at a single center between June 2004 and May 2007 receiving induction therapy with two-dose DCZ (1.5 mg/kg preoperatively and day seven post-transplant). Maintenance immunosuppression included tacrolimus, MMF, and prednisone in all patients. Forty-six percent were African American and 92% were deceased-donor transplants. After a mean follow-up of 17.8 +/- 7.5 months, acute rejection was noted in 11.5% and graft survival was 92.3%. CMV infection occurred in 11.5%, but no case of BK nephropathy or post-transplant lymphoproliferative disorder was observed. Our preliminary results suggest that induction therapy with two-dose DCZ was convenient, economical, and effective in preventing rejection episodes without an increase in adverse events or hospital stay. Larger randomized clinical trials with longer duration of follow-up are needed to more fully validate the use of this regimen in pediatric renal transplantation.

Current status and challenges of cytokine pharmacology

The major concern of pharmacology about cytokines has originated from plentiful data showing association between gross changes in their production and pathophysiological processes. Despite the enigmatic role of cytokines in diseases, a number of them have become a subject of cytokine and anti-cytokine immunotherapies. Production of cytokines can be influenced by many endogenous and exogenous stimuli including drugs. Cells of the immune system, such as macrophages and lymphocytes, are richly endowed with receptors for the mediators of physiological functions, such as biogenic amines, adenosine, prostanoids, steroids, etc. Drugs, agonists or antagonists of these receptors can directly or indirectly up- and down-regulate secretion of cytokines and expression of cytokine receptors. Vice versa, cytokines interfere with drug pharmacokinetics and pharmacodynamics through the interactions with cytochrome P450 and multiple drug resistance proteins. The aim of the review is to encourage more intensive studies in these fields of cytokine pharmacology. It also outlines major areas of searching promising candidates for immunotherapeutic interventions.

Pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on mycophenolate mofetil comedication

BACKGROUND

The aim of this substudy within a prospective, multicenter, placebo-controlled trial was to assess the pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on comedication with mycophenolate mofetil (MMF).

METHODS

Eighty-two patients aged 3 to 18 years, receiving cyclosporine microemulsion, MMF, corticosteroids, and basiliximab or placebo were investigated. Basiliximab serum concentrations were determined by ELISA, CD25+, and CD122+ T lymphocytes by flow cytometry.

RESULTS

Basiliximab clearance adjusted to body surface area was significantly (P<0.05) greater in children versus adults, but the relatively higher basiliximab dose given to children yielded similar exposure compared with adolescents. A cross-study comparison revealed that MMF reduced basiliximab clearance and prolonged CD25 saturation duration from approximately 5 weeks in the absence of MMF to 10 weeks in the presence of MMF. Basiliximab led to a marked reduction of CD25+ T-cell fraction during the first 8 to 10 weeks posttransplant, but did not specifically affect CD122+ T cells. The majority of biopsy-proven acute rejection episodes (BPAR) were observed after interleukin (IL) 2-R desaturation, whereas about a quarter of BPARs occurred despite adequate IL2-R blockade.

CONCLUSIONS

The currently recommended basiliximab dose for pediatric patients, when used with cyclosporine microemulsion and corticosteroids, yielded adequate drug exposure in children and adolescents also under MMF comedication. The observation that about a quarter of BPARs occurred despite adequate IL2-R blockade suggests that another T-cell activation pathway independent of the IL-2/IL-2R pathway is operative, for example, the IL-15 signaling pathway.

CD25 as an immune regulatory molecule expressed on myeloid dendritic cells

CD25 (alpha-chain of IL-2 receptor) on dendritic cells (DC) has been previously regarded as an activation marker. DC that concomitantly express surface CD25 and co-stimulatory molecules were considered to be fully mature. While both murine and human DC can express CD25, they do not express the beta-chain of the IL-2 receptor, which is indispensable for the execution of IL-2 signaling. The biological function of CD25 during the DC maturation therefore still remains undefined. In this review we focus on recent findings, describing CD25 expression and secretion by human myeloid regulatory DC. These DC co-express CD25 and the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) and inhibit T-cell function. CD25, expressed and secreted by such DC may capture IL-2 and thereby suppress T-cell proliferation, by this means providing an accessory mechanism of DC-mediated immune suppression. We also discuss the implication of DC-derived CD25 for human disease in both cancer and chronic infection.

Neural precursor cells inhibit multiple inflammatory signals

Intravenous neural precursor cell (NPCs) injection attenuates experimental autoimmune encephalomyelitis by reducing autoreactive T cell encephalitogenicity in lymph nodes in vivo. Here we examined NPC-lymphocyte interactions in vitro. NPCs inhibited the induction of T cell activation marker IL-2-Receptor alpha, ICOS, PD-1 and CTLA-4 and inhibited T cell proliferation. NPCs inhibited T cell activation and proliferation in response to Concavalin-A and to anti-CD3/anti-CD28, which are T cell receptor (TCR)-mediated stimuli, but not in response to phorbol myristate acetate/ionomycin, a TCR-independent stimulus. The suppressive effect was not mediated via downregulation of CD3epsilon or induction of apoptosis. We next examined NPCs effects on inflammatory-cytokine signaling. NPCs impaired IL-2-mediated phosphorylation of JAK3 in lymphocytes, and inhibited IL-6 mediated proliferation of B9 murine hybridoma cells. In conclusion, NPCs ameliorate TCR-mediated T cell activation and inhibit inflammatory cytokines' signaling in immune cells. These findings may underlie the broad anti-inflammatory effects of NPCs in vivo.

Serum soluble interleukin 2 receptor alpha in human cancer of adults and children: a review

Cancer growth and development is associated with the stimulation of the innate immune system, including enhanced interleukin 2 receptor (IL-2R) expression in immune cells and its shedding into the circulation in a soluble form of sIL-2Ralpha. In most haematological malignancies, including different types of leukaemias and lymphomas, sIL-2Ralpha has been found to be released directly from the surface of neoplastic cells thus reflecting the tumour bulk, turnover and activity. Several studies have proved that not only lymphoid cancer cells, but also some non-lymphoid cancer cells, express IL-2R on their surface. They include malignant melanoma and carcinomas of the kidney, head and neck, oesophagus and lung. It is suggested that in most malignant solid tumours, elevated levels of sIL-2Ralpha are likely to be the product of normal peripheral mononuclear cells activated in response to the neoplasm's growth or that they are released from activated lymphoid cells infiltrating neoplastic tissues. This latter hypothesis has been proved by discovering the high expression of CD25 on the cell surface of most of these cells. Although the precise source and biological role of sIL-2Ralpha has not been clarified definitively, pretreatment serum levels of sIL-2Ralpha have been shown to reflect the activity, advancement and biological aggressiveness of many types of cancer in adults and children as well as to correlate with prognosis and overall survival. The possibility of enriching the diagnostic tools of oncologists with a new biochemical marker of activity of neoplasms resulted in numerous studies and reports concerning the clinical usefulness of sIL-2Ralpha measurements in adult and, less frequently, in paediatric malignancies. This article presents the actual knowledge concerning the structure, source and biological function of sIL-2Ralpha in patients with haematological and non-haematological malignancies. The authors review the published data on clinical applicability of soluble IL-2Ralpha determination in terms of diagnostics, prognosis and treatment monitoring of particular types of malignant disorders both in adults and in children. They also provide an insight into the clinical usefulness of sLL-2Ralpha-blocking antibodies in patients with cancer, and in those who reject organ transplants, develop graft-versus-host disease after allogeneic bone marrow transplantation and are affected with autoimmune disorders.

The long-term outcomes of pediatric kidney transplantation: a single-centre experience in China

To explore the long-term outcomes of paediatric kidney transplantation and the effects of renal allograft on growth, education, employment, marriage and procreation. Twenty-seven children with ESRD received the renal allograft from 1985 to 2001. The patient and kidney survival rate, renal function, growth and employment, etc., were reviewed retrospectively. The average follow-up period was 10.3 +/- 4.4 yr. The one-, three-, five- and 10-yr graft survival rates were 96.3%, 88.9%, 81.5% and 66.7%, respectively, and the corresponding patient survival rates were 100%, 92.6%, 85.2% and 68.8%. The body weight gain was 4-10 kg in one-yr post-operative and the height increased 0-2 cm for girls and 2-5 cm for boys. A total of 44.4% of the recipients accomplished their education above junior high school. The employment rate was 46.2% in males, and 57.2% in females. Twelve patients were married. Non-adherence occurred in 30% of the recipients. Forty percent of the surviving recipients developed complications. Seven patients died. More attention should be paid to non-adherence of medications and more supports from the society are required to improve the life quality of paediatric recipients, especially in employment and education.

Induction therapy in pediatric renal transplant recipients: an overview

Induction therapy to prevent the acute rejection of mismatched allografts with the ultimate aim of prolonging the life of the allograft has been the cornerstone of immunosuppression since the introduction of renal transplantation. Agents used for induction therapy have changed over time. Their role in transplantation is expanding to include corticosteroid avoidance and immunosuppression minimization. This review provides an overview of induction therapies for renal transplantation including historic therapies such as total lymphoid irradiation and Minnesota antilymphocyte globulin, and current therapies with polyclonal and monoclonal antibodies and chemical agents, with special emphasis on children. Data from adult studies, and pediatric studies whenever available, are summarized. A brief summary of experimental therapies with fingolimod and belatacept is provided. Historically, induction therapies were targeted at T cells. The role of induction therapies targeted at B cells is emerging in select groups of patients that include highly sensitized recipients and those receiving transplants from blood group incompatible donors. With the advent of newer maintenance immunosuppressive medications and with very low rates of acute rejection, induction protocols for renal transplantation need to be targeted so that excessive immunosuppression and infections are avoided. Several single-center and registry data analyses in children suggest that the addition of an interleukin (IL)-2 receptor antagonist may improve graft survival compared with no induction. The safety profile of IL-2 receptor antagonists is indistinguishable from that of placebo, with no apparent difference in the incidence of infection or post-transplant lymphoproliferative disease. IL-2 receptor antagonists and polyclonal lymphocyte-depleting antibodies offer equivalent efficacy in standard-risk populations. However, in high-risk patients, acute rejection rates and graft outcomes may be improved with the use of lymphocyte-depleting agents such as Thymoglobulin. However, cytomegalovirus infection and other infections may be more common with this therapy. Therefore, in patients at high risk of graft loss, Thymoglobulin may be the preferred choice for induction therapy, while for all other patients, IL-2 receptor antagonists should be considered the first-line choice for induction therapy. Newer lymphocyte-depleting agents such as alemtuzumab may be better utilized in minimization regimens involving one or two oral maintenance immunosuppressive agents.

Critical care perspective on immunotherapy in lung transplantation

Lung transplantation is now a viable therapeutic option in the care of patients with advanced pulmonary parenchymal or pulmonary vascular disease. Lung transplantation, however, with chronic posttransplant immunosuppression, creates a uniquely vulnerable population of patients likely to experience significant life-threatening complications requiring intensive care. The introduction of several novel immunosuppressive agents, such as sirolimus and mycophenolate mofetil, in conjunction with more established agents such as cyclosporine and tacrolimus, has greatly increased treatment options for lung transplant recipients and likely contributed to improved short-term transplant outcomes. Modern transplant immunosuppression, however, is associated with a host of complications such as opportunistic infections, renal failure, and thrombotic thrombocytopenic purpura. The main focus of this review is to provide a comprehensive summary of modern immunotherapy in lung transplantation and to increase awareness of the serious and potentially life-threatening complications of these medications.

CD4+CD25+Regulatory T Cells and Their Therapeutic Potential

The human immune system mounts specific responses to a vast array of antigens. Although this is clearly beneficial in fighting off harmful infections and cancerous cells, the system must be carefully controlled to ensure that normal self-antigens are not targeted. A recently characterized subset of T cells, identified by their cell surface expression of CD4 and CD25, is critical in regulating the function of other immune cells and preventing potentially harmful autoimmune responses. This article reviews what is currently known about these so-called regulatory T cells and discusses the therapeutic potential of these cells to modulate human immune-based diseases.

Daclizumab for children with corticosteroid refractory graft-versus-host disease

Daclizumab, a humanized IL-2 receptor antagonist, has been found to be safe and effective in adults with refractory graft-versus-host disease (GVHD); however, data describing its efficacy for refractory GVHD in children are limited. We report a series of 14 children who were treated with daclizumab for severe acute and/or chronic corticosteroid refractory GVHD. Patients were treated with 2 mg/kg weekly for 8 weeks followed by 1 mg/kg weekly for 4 weeks. Nine of 14 patients responded to daclizumab as measured by improvement of GVHD symptoms, and the ability to substantially wean corticosteroid dose. Five of 11 patients with acute GVHD had complete symptom resolution, and 2/11 had a partial response. Two of four patients with chronic GVHD had complete symptom resolution. In these patients, daclizumab was only effective in treating skin GVHD. Seven of the nine patients who had a complete or partial response eventually had recurrence of GVHD; however, the GVHD was less severe and no longer corticosteroid refractory. There was no infusional toxicity, and no infections that could be attributable to the drug. Daclizumab is a relatively safe and effective medication for corticosteroid refractory GVHD in children and larger studies are needed to evaluate its role in treatment.