Valganciclovir Administration to Kidney Donors to Reduce the Burden of Cytomegalovirus and Epstein-Barr Virus Transmission During Transplantation

The IPTA Nashville consensus conference on Post-Transplant lymphoproliferative disorders after solid organ transplantation in children: II-consensus guidelines for prevention

The International Pediatric Transplant Association (IPTA) convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorder after solid organ transplantation in children. In this report from the Prevention Working Group, we reviewed the existing literature regarding immunoprophylaxis and chemoprophylaxis, and pre-emptive strategies. While the group made a strong recommendation for pre-emptive reduction of immunosuppression at the time of EBV DNAemia (low to moderate evidence), no recommendations for use could be made for any prophylactic strategy or alternate pre-emptive strategy, largely due to insufficient or conflicting evidence. Current gaps and future research priorities are highlighted.

Valganciclovir is not associated with decreased EBV infection rate in pediatric kidney transplantation

INTRODUCTION

Primary infection or reactivation of Epstein-Barr Virus (EBV) is a significant cause of morbidity and mortality in pediatric kidney transplantation. Valganciclovir (VGC) treatment is recommended for prophylaxis of cytomegalovirus infection, but its role for the prevention of EBV infection remains controversial.

PATIENTS AND METHODS

All pediatric kidney transplant recipients aged <18 years old were considered for inclusion in this retrospective study. EBV negative recipients with an EBV positive donor (a group at risk of primary infection) or EBV positive recipients (a group at risk of reactivation) were included. Severe infection was defined by post-transplant lymphoproliferative disorder (PTLD), symptomatic EBV infection or by asymptomatic EBV infection with a viral load >4.5 log/ml. Outcomes were compared between patients receiving VGC prophylaxis (group P+) and those not receiving VGC prophylaxis (group P-).

RESULTS

A total of 79 patients were included, 57 (72%) in the P+ group and 22 (28%) in the P- group; 25 (31%) were at risk of primary infection and 54 (69%) at risk of reactivation. During the first year post-transplant, the occurrence of severe EBV infection was not different between the P+ group (n = 13, 22.8%) and the P- group (n = 5, 22.7%) (p = 0.99). Among patients at risk of primary infection, the rate of severe EBV infection was not different between the two groups (42.1% in P+ vs. 33.3% in P-). A higher frequency of neutropenia was found in the P+ group (66.6%) than in the P- group (33.4%) (p < 0.01).

CONCLUSION

Our observational study suggests no effect of VGC for the prevention of EBV infection in pediatric kidney transplant recipients, irrespective of their EBV status. Adverse effects revealed an increased risk of neutropenia.

Cytomegalovirus transmission in mismatched solid organ transplant recipients: Are factors other than anti-viral prophylaxis at play?

Although antiviral prophylaxis has reduced cytomegalovirus (CMV) DNAemia and disease in seronegative solid organ transplant (SOT) recipients (R-) receiving seropositive donor organs (D+), its impact on CMV transmission is uncertain. Transmission, defined as CMV antigenemia/CMV DNAemia and/or seroconversion by year 2, and associated demographic risk factors were studied retrospectively in 428 D+/R- and 429 D-/R- patients receiving a SOT at our center. The cumulative transmission incidence was higher for lung (90.5%) and liver recipients (85.1%) than heart (72.7%), kidney (63.9%), and pancreas (56.2%) recipients (p < .001) and was significantly lower in living (50.1%) versus deceased donor (77.4%, p < .001) kidney recipients despite identical antiviral prophylaxis. In multivariate analysis, only allograft type predicted transmission risk (HR [CI] lung 1.609 [1.159, 2.234] and liver 1.644 [1.209, 2.234] vs kidney). For 53 D+ donating to >1 R- with adequate follow-up, 43 transmitted to all, three transmitted to none, and seven transmitted inconsistently with lungs and livers always transmitting but donor-matched heart, kidney or kidney-pancreas allografts sometimes not. Kidney pairs transmitted concordantly. CMV transmission risk is allograft-specific and unchanged despite antiviral prophylaxis. Tracking transmission and defining donor factors associated with transmission escape may provide novel opportunities for more targeted CMV prevention and improve outcome analysis in antiviral and vaccine trials.

Prophylactic and Therapeutic EBV Vaccines: Major Scientific Obstacles, Historical Progress, and Future Direction

The Epstein-Barr virus (EBV) infects more than 95% of adults worldwide and is associated with various malignant tumors and immune diseases, imparting a huge disease burden on the human population. Available EBV vaccines are imminent. Prophylactic vaccines can effectively prevent the spread of infection, whereas therapeutic vaccines mainly stimulate cell-mediated immunity and kill infected cells, thus curbing the development of malignant tumors. Nevertheless, there are still no approved EBV vaccines after decades of effort. The complexity of the EBV life cycle, the lack of appropriate animal models, and the limited reports on adjuvant selection and immune responses are gravely impeding progress in EBV vaccines. The soluble gp350 vaccine could reduce the incidence of infectious mononucleosis (IM), which seemed to offer hope, but could not prevent EBV infection. Continuous research and vaccine trials provide deep insights into the structural biology of viruses, the designs for immunogenicity, and the evolving vaccine platforms. Moreover, the new vaccine candidates are expected to achieve further success via combined immunization to elicit both a dual protection of B cells and epithelial cells, and sustainable immunization against infected cells at several phases of infection.

Donor CMV Reactivation as a Novel Risk Factor for CMV Replication in Seropositive Liver Transplant Recipients

Risk factors for cytomegalovirus (CMV) viremia in CMV seropositive liver transplant recipients are incompletely defined and have focused primarily on recipient factors. We hypothesized that active CMV replication (CMV viremia) in seropositive donors might increase the risk for CMV viremia in recipients, as reported for other viruses in organ transplantation.

Efficacy and Safety of a Weight-based Dosing Regimen of Valganciclovir for Cytomegalovirus Prophylaxis in Pediatric Solid-organ Transplant Recipients

BACKGROUND

Valganciclovir has been widely used for cytomegalovirus (CMV) prophylaxis in solid-organ transplant recipients. However, the optimal dosing protocol and target exposure in children are still unclear. Specific data as to the efficacy and safety of low-dose/low-exposure regimens are lacking and urgently needed.

METHODS

During 2010 to 2015, the clinical efficacy and safety of a weight-based regimen of valganciclovir of 17 mg/kg/day, with a stratified dose reduction for impaired creatinine clearance, given as a CMV prophylaxis for 3 to 6 months, was retrospectively evaluated among pediatric kidney and liver transplant recipients, 12 months posttransplantation. Incidence of CMV infection was assessed by periodic measurements of viral load; adverse events were evaluated.

RESULTS

Eighty-three children who had undergone 86 transplantations and were treated with 17 mg/kg of valganciclovir were included. Median age was 9.77 years (range, 0.6 to 18.9). Twelve (14%) developed CMV infection: 1 during prophylaxis and 11 during follow-up. These events comprised 6 cases of asymptomatic viremia and 6 cases of a clinically significant disease without occurrences of tissue-invasive disease. Treatment-related adverse effects occurred in 7 patients (8%), mostly hematological, resulting in premature drug cessation.

CONCLUSIONS

Our results support the use of 17 mg/kg of valganciclovir for CMV prophylaxis in liver and kidney transplanted children as it showed satisfactory long-term efficacy and a good safety profile.

Post-transplant lymphoproliferative disorders, Epstein-Barr virus infection, and disease in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

PTLD with the response-dependent sequential use of RIS, rituximab, and cytotoxic chemotherapy is recommended. Evidence gaps requiring future research and alternate treatment strategies including immunotherapy are highlighted.

Risk factors associated with post-kidney transplant malignancies: an article from the Cancer-Kidney International Network

In kidney transplant recipients, cancer is one of the leading causes of death with a functioning graft beyond the first year of kidney transplantation, and malignancies account for 8-10% of all deaths in the USA (2.6 deaths/1000 patient-years) and exceed 30% of deaths in Australia (5/1000 patient-years) in kidney transplant recipients. Patient-, transplant- and medication-related factors contribute to the increased cancer risk following kidney transplantation. While it is well established that the overall immunosuppressive dose is associated with an increased risk for cancer following transplantation, the contributive effect of different immunosuppressive agents is not well established. In this review we will discuss the different risk factors for malignancies after kidney transplantation.

Primary Epstein-Barr virus infection

Epstein-Barr virus (EBV) infects about 90% of adults worldwide. It is the main cause of infectious mononucleosis, which is observed most frequently in adolescents. The disease can last several weeks and is characterized by lymphocytosis, sore throat, lymphadenopathy, and fatigue. Exposure to oral secretions during deep kissing has been identified as the major source for primary EBV infection in adolescents. Oral secretions are also thought to be the source for younger children through intimate intact or sharing food and eating utensils, although this has not been confirmed. Unlike most acute viral illnesses such as influenza, the incubation period of symptomatic primary EBV infection is unusually long, lasting about six weeks. Diagnosis is typically made by heterophile antibody tests and/or EBV-specific antibody tests. Long-term consequences may result from acquisition of the virus, including nasopharyngeal carcinoma and lymphomas. Nevertheless, there remains a surprising dearth of knowledge regarding the establishment of an immune response to persistent EBV infection, especially during the incubation period. This lack of knowledge has impaired our ability to develop an effective prophylactic EBV vaccine, despite various attempts. Our greatest challenges in EBV research are to develop a prophylactic vaccine and devise treatment strategies for persons already infected with EBV.

Comprehensive review of post-organ transplant hematologic cancers

A higher risk for a variety of cancers is among the major complications of posttransplantation immunosuppression. In this part of a continuing series on cancers posttransplantation, this review focuses on the hematologic cancers after solid organ transplantation. Posttransplantation lymphoproliferative disorders (PTLDs), which comprise the great majority of hematologic cancers, represent a spectrum of conditions that include, but are not limited to, the Hodgkin and non-Hodgkin lymphomas. The oncogenic Epstein-Barr virus is a key pathogenic driver in many PTLD cases, through known and unknown mechanisms. The other hematologic cancers include leukemias and plasma cell neoplasms (multiple myeloma and plasmacytoma). Clinical features vary across malignancies and location. Preventive screening strategies have been attempted mainly for PTLDs. Treatments include the chemotherapy regimens for the specific cancers, but also include reduction of immunosuppression, rituximab, and other therapies.

Valganciclovir Dosing for Cytomegalovirus Prophylaxis in Pediatric Solid-organ Transplant Recipients: A Prospective Pharmacokinetic Study

BACKGROUND

Valganciclovir is extensively used for prophylaxis and treatment of cytomegalovirus (CMV) infection in solid-organ transplant recipients. However, pharmacokinetic data in children are scarce, and the pediatric dosing regimen is uncertain. This study sought to prospectively evaluate the pharmacokinetic profile, the clinical efficacy and safety of oral valganciclovir in pediatric transplant recipients and compare different dosing regimens.

METHODS

The cohort included solid-organ transplant recipients treated with valganciclovir for CMV prophylaxis in 2014-2015 at a tertiary pediatric medical center. All received a weight-based once-daily oral dose of 17 mg/kg. Ganciclovir concentrations were measured and the area under the curve (AUC0-24) was calculated.

RESULTS

Thirteen children of median age 7.3 years (interquartile range, 2.2-11.6) were included. Median ganciclovir AUC0-24 was 21.0 mcg·h/mL (interquartile range, 17.1-39.8); 10 patients (77%) attained AUC0-24 <40 mcg·h/mL. Exposure to ganciclovir was about 2-fold lower in young children (<9 years old; P = 0.01) and children with low body surface area (BSA; <0.7 m; P = 0.006) than in their counterparts. Significantly lower doses were recommended with our weight-based protocol than with the manufacturer-recommended BSA- and glomerular filtration rate-based protocol (P = 0.002), reaching a 3-fold difference in infants. No evidence of CMV viremia or disease was observed while prophylaxis was given.

CONCLUSIONS

The weight-based regimen of 17 mg/kg/dose oral valganciclovir results in relatively low ganciclovir exposure, especially in young children with low BSA, yet showed satisfactory clinical efficacy for CMV prophylaxis. The manufacturer's dosing recommendation appears to result in supratherapeutic ganciclovir concentrations. Further studies are needed to establish target AUCs and valganciclovir dosing for CMV prophylaxis in pediatric transplant recipients.

Pediatric kidney transplantation: a historical review

Successful renal transplantation is the optimal treatment for chronic kidney failure, but this was not always so for children. Beginning with the first kidney transplants in the 1950s, children experienced poorer patient and graft survival rates than adult patients. But over the last 6 decades, an improved understanding of the immune system which has steered pediatric multi-center clinical/pharmacokinetic and mechanistic studies that have sculpted our immunosuppression with markedly better patient and graft survivals. In addition, uniquely pediatric issues related to growth, development, neurocognitive maturation, increased complications from primary viral infections, and comorbid congenital/inherited disorders, are now diagnosed and effectively managed in these children. Refined pretransplant preparation (vaccinations for preventable diseases, attention to cognitive delays, effective dialysis and nutrition) improved donor selection, and more potent immunosuppression have all contributed to enhanced outcomes. Similarly, improvements in pediatric surgical techniques, postoperative care and better antiviral prophylaxis have all shortened hospitalizations and reduced morbidity. Today pediatric kidney transplant outcomes are markedly improved and younger children today experience better long-term graft survival than adults! While difficult problems remain, we have made tremendous progress and anticipate even more advances in the future of pediatric kidney transplantation.

Epstein-Barr virus dynamics in asymptomatic immunocompetent adults: an intensive 6-month study

Characterizing Epstein-Barr virus (EBV) dynamics in asymptomatic immunocompetent persons provides a baseline for defining quantitative thresholds associated with EBV disease. Studying latent membrane protein (LMP)-1 sequence variation over time could establish the rates of reactivation and superinfection, and also trace transmission. Twelve asymptomatic adult subjects were evaluated prospectively nine times over 6 months. EBV serum antibodies were measured by enzyme immunoassay. EBV DNA in oral and whole-blood samples was quantitated by real-time (TaqMan) PCR and analyzed for LMP-1 sequence variability. All 11 antibody positive subjects had EBV DNA detected in their oral compartment at least once during the 6-month study. The quantities ranged from 1.70 to 4.91 log10 copies EBV per ml of oral cell pellet. One subject was continuously viremic for 79 days. Overall, EBV DNA was detected in 63 (24%) of 260 samples from 11 antibody-positive subjects and in 0/27 samples from an antibody-negative subject. The quantities in positive samples ranged from 1.7 to 4.9 log10 copies EBV per ml. EBV LMP-1 gene sequence variations in subjects were constant over time regardless of the compartment sampled. Subjects 18-30 years old had EBV DNA detected more frequently than subjects >30 years old (38/108 positive samples versus 25/152; P<0.001). In conclusion, EBV DNA shedding is common in asymptomatic adults. The younger adults shed more frequently, which may reflect a shorter time from their primary EBV infection to sampling. The LMP-1 sequence analysis method employed here could be used to trace person-to-person transmission because patterns remained almost identical over time.

Post-transplant lymphoproliferative disorders

Post-transplant lymphoproliferative disorders (PTLDs) are a group of conditions that involve uncontrolled proliferation of lymphoid cells as a consequence of extrinsic immunosuppression after organ or haematopoietic stem cell transplant. PTLDs show some similarities to classic lymphomas in the non-immunosuppressed general population. The oncogenic Epstein-Barr virus (EBV) is a key pathogenic driver in many early-onset cases, through multiple mechanisms. The incidence of PTLD varies with the type of transplant; a clear distinction should therefore be made between the conditions after solid organ transplant and after haematopoietic stem cell transplant. Recipient EBV seronegativity and the intensity of immunosuppression are among key risk factors. Symptoms and signs depend on the localization of the lymphoid masses. Diagnosis requires histopathology, although imaging techniques can provide additional supportive evidence. Pre-emptive intervention based on monitoring EBV levels in blood has emerged as the preferred strategy for PTLD prevention. Treatment of established disease includes reduction of immunosuppression and/or administration of rituximab (a B cell-specific antibody against CD20), chemotherapy and EBV-specific cytotoxic T cells. Despite these strategies, the mortality and morbidity remains considerable. Patient outcome is influenced by the severity of presentation, treatment-related complications and risk of allograft loss. New innovative treatment options hold promise for changing the outlook in the future.