Induction therapy in pediatric renal transplant recipients: an overview

Rituximab as induction therapy in pediatric kidney transplantation: A single-center experience in four patients

BACKGROUND

The anti-CD20 rituximab is often used in the treatment of children with steroid-resistant nephrotic syndrome or EBV-induced post-transplant lymphoproliferative disorder. This single-center series reports the use of rituximab as induction therapy in pediatric kidney transplantation.

METHODS

Four children who received rituximab as induction therapy for kidney transplantation since 2016 were retrospectively analyzed. Clinical and laboratory data were extracted from medical records.

RESULTS

The patients (2 boys and 2 girls) were aged from 6.1 to 11.9 years and were treated with rituximab on the day of the transplantation procedure; all the transplants came from deceased donors. In all patients, rituximab was used because of positive EBV viral loads before kidney transplantation. Viral loads remained undetectable for the first 6 months after the transplantation procedure and remained below the 4.5 log threshold thereafter. After a median follow-up of 2.3 years, none of the patients displayed rejection or de novo donor-specific antibodies; the glomerular filtration rate remained above 70 ml/min/1.73 m² . No post-transplant lymphoproliferative disorder was observed.

CONCLUSION

The results suggest that rituximab can be used as induction therapy to prevent EBV replication and its complications in case of positive viral load prior to kidney transplantation.

Lymphocyte-depleting induction therapy lowers the risk of acute rejection in African American pediatric kidney transplant recipients

The use of lymphocyte-depleting induction immunosuppression has been associated with a reduction in risk of AR after KT among adult recipients, particularly among high-risk subgroups such as AAs. However, data on induction regimen and AR risk are lacking among pediatric KT recipients. We examined outcomes among 7884 first-time pediatric KT recipients using SRTR data (2000-2014). Characteristics were compared across race using Wilcoxon rank-sum tests for continuous and chi-square tests for categorical variables. Risk of AR was estimated using modified Poisson regression, stratified by recipient race, adjusting for recipient age, gender, BMI, primary diagnosis, number of HLA mismatches, maintenance immunosuppression, and donor type. Risk of AR within 1 year was lower in AA recipients receiving lymphocyte-depleting induction (ATG or alemtuzumab; RR, 0.66; 95% CI, 0.52-0.83 P < .001) compared to AA recipients receiving anti-IL-2 receptor antibody induction. This difference was not seen in non-AA recipients receiving lymphocyte-depleting induction (RR, 0.93; 95% CI, 0.81-1.06, P = .26) compared to IL-2 induction. These findings support a role for lymphocyte-depleting induction agents in AA pediatric patients undergoing KT and continued use of IL-2 inhibitor induction in non-AA pediatric KT recipients.

Alemtuzumab with corticosteroid minimization for pediatric deceased donor renal transplantation: a seven-yr experience

Alemtuzumab is a monoclonal antibody targeting CD52 receptors on B and T lymphocytes and is an effective induction agent in pediatric renal transplantation. We report a seven-yr experience using alemtuzumab induction and steroid-free protocol in the pediatric population as safe and effective. Twenty-one pediatric deceased donor renal transplants were performed at a single academic institution. All received induction with single-dose alemtuzumab and were maintained on a steroid-free protocol using TAC and MMF immunosuppression. There were 15 males and six females in the study whose ages ranged from one to 19 yr. The average follow-up was 32 months (range from 12 to 78.2 months and median 33.7 ± 23.7 months). All patients had immediate graft function. Graft survival was 95%, and patient survival was 100%. Mean 12 and 36 months eGFR were 63.33 ± 21.01 and 59.90 ± 15.27 mL/min/1.73m(2), respectively. Three patients developed acute T-cell-mediated rejection due to non-adherence while no recipients developed cytomegalovirus infection, PTLD, or polyoma BK viral nephropathy. Steroid avoidance with single-dose alemtuzumab induction provides adequate and safe immunosuppression in pediatric deceased donor renal transplant recipients receiving TAC and low-dose MMF maintenance therapy.

New immunosuppressive agents in pediatric transplantation

Immunosuppressive therapy in pediatrics continues to evolve. Over the past decade, newer immunosuppressive agents have been introduced into adult and pediatric transplant patients with the goal of improving patient and allograft survival. Unfortunately, large-scale randomized clinical trials are not commonly performed in children. The purpose of this review is to discuss the newer immunosuppressive agents available for induction therapy, maintenance immunosuppression, and the treatment of rejection.

Primer on renal transplantation

Renal transplantation transforms chronically ill children with end stage renal disease (ESRD) into near normal resulting in improvement in nutrition, growth, neurodevelopment and quality of life, and is the goal of therapy. However, the benefits of transplantation come at a price of life-long treatment with immunosuppressive medications, increased risk of infections and malignancy. Children younger than 10 y of age have the best, and adolescents have the worst 5-y graft survival likely due to non-adherence with medications in the adolescents. Long-term complications include ongoing issues related to chronic kidney disease (CKD) and cardiovascular morbidity and mortality contributing to graft loss and shortened life expectancy, thus limiting the success of organ transplantation. Therefore, appropriate management of CKD and cardiovascular issues should be integral to the care of pediatric transplant patients. The other ongoing challenges include organ shortage, prevention and treatment of late acute rejections and chronic graft dysfunction, discovering reliable noninvasive immune monitoring tools, improving adherence, psychosocial rehabilitation, and the elusive goal of tolerance.

Immune profile of pediatric renal transplant recipients following alemtuzumab induction

The incidence of developing circulating anti-human leukocyte antigen antibodies and the kinetics of T cell depletion and recovery among pediatric renal transplant recipients who receive alemtuzumab induction therapy are unknown. In a collaborative endeavor to minimize maintenance immunosuppression in pediatric renal transplant recipients, we enrolled 35 participants from four centers and treated them with alemtuzumab induction therapy and a steroid-free, calcineurin-inhibitor-withdrawal maintenance regimen. At 3 months after transplant, there was greater depletion of CD4(+) than CD8(+) T cells within the total, naive, memory, and effector memory subsets, although depletion of the central memory subset was similar for CD4(+) and CD8(+) cells. Although CD8(+) T cells recovered faster than CD4(+) subsets overall, they failed to return to pretransplant levels by 24 months after transplant. There was no evidence for greater recovery of either CD4(+) or CD8(+) memory cells than naïve cells. Alemtuzumab relatively spared CD4(+)CD25(+)FoxP3(+) regulatory T cells, resulting in a rise in their numbers relative to total CD4(+) cells and a ratio that remained at least at pretransplant levels throughout the study period. Seven participants (20%) developed anti-human leukocyte antigen antibodies without adversely affecting allograft function or histology on 2-year biopsies. Long-term follow-up is underway to assess the potential benefits of this regimen in children.

[Biological therapy in pediatrics]

In the late 1980s, the murine monoclonal antibody muromonab was used in children undergoing organ transplantation. Since then, dozens of new molecules have been developed to modulate the immune response, block growth factors, or prevent infections on the basis of the antigen-antibody-specific response. In pediatrics, most biological therapies are used off-label, although they are effective and well tolerated and are used as first-line therapy in some severe genetic diseases. Biologicals allow specific targeting and can be engineered against any antigen. The safety of these treatments varies depending on the molecule and precise knowledge of side effects is essential for clinicians. The development of these promising agents requires clinical trials in children to validate their effectiveness and safety in the medium and long term.

Variables affecting estimated glomerular filtration rate after renal transplantation in children: a NAPRTCS data analysis

Short-term graft survival has improved in renal transplants without significant effect on long-term graft survival. As GFR decline precedes graft loss, an understanding of variables affecting eGFR after TX may help improve graft survival. NAPRTCS data were analyzed to assess effects of donor, recipient, and other variables on Schwartz eGFR after transplantation. For 8438 children with a functioning graft at day 30, data were censored for children dying with a functioning graft, and those with <3 yr follow-up. Multivariate linear regression and repeated measures analyses identified factors related to eGFR at day 30 after TX and during follow-up. Young, female, non-black, children without ATN and acute rejection in the first 30 days, TX after 1995, those with better eGFR at day 30, and receiving tacrolimus had better long-term eGFR. Transplant from ideal (6-35 yr) donors had best short-term eGFR, young donors (<5 yr) had lower eGFR and poor graft survival. After one yr, eGFR improved in surviving grafts of young donors and matched ideal donors. Acute rejection, BP medications, and hospitalizations in prior six months had negative association with subsequent eGFR. Regardless of variables, eGFR deteriorated with time. Slope of eGFR decline has not changed in the recent era indicating the need for innovative therapies.

Yin and yang of cytokine regulation in solid organ graft rejection and tolerance

Solid organ transplantation is the therapy of choice for end stage diseases. The alloimmune response generated after transplantation induces the production of a "cytokine storm" that can lead to either the rejection of the organ or graft acceptance. These key decisions, which determine the transplant fate, depend on the type of cytokine response (Th1/Th2). An inflammatory response will lead to graft loss; a tolerogenic response assists in graft acceptance. A balance between different factors often determines outcome. The same cytokine may assist in either allograft rejection or graft survival depending on: (1) the cell types in the vicinity, (2) the amount of each cytokine produced, (3) different sites, and (4) if it acts in a synergistic or antagonistic manner with other cytokines. This review focuses on cytokines that manipulate the alloimmune response after organ transplantation and that play a role either in graft rejection (yin) or tolerance (yang).

Helical tomotherapy for total lymphoid irradiation

Total lymphoid irradiation is employed in the preparative regimens for allogeneic bone marrow and solid organ transplantation, solid organ transplant rejection, and chronic graft-versus-host disease. Linear accelerator-based radiotherapy, typically involving opposed anteroposterior and posteroanterior beams, has been commonly used; however, extended source-to-skin patient setup and/or field matching are required, and all organs within the beam coverage receive the entire prescribed dose. Megavoltage helical tomotherapy represents a technological advance in terms of both treatment delivery and patient positioning. The continuously rotating multileaf collimated fan beam allows highly conformal coverage of complex target geometries, in turn allowing avoidance of radiosensitive adjacent organs. In addition, the megavoltage computed tomographic scans allow potentially more accurate, targetbased setup verification. The present case report describes tomotherapy-based total lymphoid irradiation in an adult patient with late-onset cardiac transplant rejection. Treatment planning allowed dose minimization to the spinal cord, kidneys, intestinal compartment, and lungs. The patient tolerated treatment well without acute adverse effects, and he is now in early follow-up.