Cytomegalovirus infection and allograft rejection among pediatric heart transplant recipients in the era of valganciclovir prophylaxis

Multicenter Analysis of Valganciclovir Prophylaxis in Pediatric Solid Organ Transplant Recipients

Background

Valganciclovir is the only approved antiviral for cytomegalovirus (CMV) prevention in pediatric solid organ transplantation (SOT). Additional approaches may be needed to improve outcomes.

Methods

A multicenter retrospective study from 2016 to 2019 was conducted of pediatric SOT recipients in whom at least 3 months of valganciclovir prophylaxis was planned. Episodes of CMV DNA in blood (DNAemia), CMV disease, drug-related toxicities, as well as other infections in the first year posttransplant and demographic and clinical data were collected. CMV DNAemia in the first year after prophylaxis or during prophylaxis (breakthrough) was analyzed by multivariate hazard models.

Results

Among the 749 patients enrolled, 131 (17.5%) had CMV DNAemia at any time in the first year; 85 (11.4%) had breakthrough DNAemia, and 46 (6.1%) had DNAemia after prophylaxis. CMV disease occurred in 30 (4%). In a multivariate model, liver transplantation compared to kidney or heart, intermediate or high risk based on donor/recipient serologies, neutropenia, and valganciclovir dose modifications attributed to toxicity were associated with increased risk of total and/or breakthrough DNAemia. Bacteremia was also associated with increased hazard ratio for CMV DNAemia. In a separate multivariate analysis, rejection occurred more often in those with breakthrough CMV DNAemia (P = .002); liver transplants, specifically, had increased rejection if CMV DNAemia occurred in the first year (P = .004). These associations may be bidirectional as rejection may contribute to infection risk.

Conclusions

CMV DNAemia in the first year posttransplantation occurs despite valganciclovir prophylaxis and is associated with medication toxicity, bacteremia, and rejection. Pediatric studies of newer antivirals, especially in higher-risk subpopulations, appear to be warranted.

Current and Emerging Antiviral Agents in the Prevention and Treatment of Cytomegalovirus in Pediatric Transplant Recipients

Despite current prophylaxis regimens, cytomegalovirus (CMV) is common in hematopoietic cell transplantation (HCT) and solid organ transplantation (SOT) and remains a significant cause of morbidity and mortality. Newer antiviral medications are reshaping the landscape for prevention and treatment of CMV DNAemia, infection, and disease. Letermovir is approved for CMV prevention in adult HCT patients and is attractive due to the absence of marrow suppression seen with ganciclovir/valganciclovir. Letermovir should not be routinely used for CMV treatment due to its low threshold for resistance. Maribavir is approved for the treatment of refractory or resistant CMV disease in HCT and SOT recipients ≥12 years of age, though it has no current role in CMV prevention. More research is needed to fully elucidate the roles, efficacy, and safety of these newer agents in prevention and treatment of CMV in pediatric transplant recipients.

Update on Epidemiology and Outcomes of Infection in Pediatric Organ Transplant Recipients

Pediatric solid organ transplant (SOT) recipients are at risk for infection following transplantation. Data from adult SOT recipients are often used to guide prevention and treatment of infections associated with organ transplantation in children. This article highlights key recent pediatric SOT-specific publications for an array of infectious complications of organ transplantation. Attention is given to areas of need for future study.

Epidemiology, management, and burden of cytomegalovirus in solid organ transplant recipients in selected countries outside of Europe and North America: A systematic review

BACKGROUND

Cytomegalovirus (CMV) is a frequent infectious complication following solid organ transplantation (SOT). Considering significant differences in healthcare systems, a systematic review was conducted to describe the epidemiology, management, and burden of CMV post-SOT in selected countries outside of Europe and North America.

METHODS

MEDLINE, Embase, and Cochrane databases were searched for observational studies in SOT recipients across 15 countries in the regions of Asia, Pacific, and Latin America (search period: January 1, 2011 to September 17, 2021). Outcomes included incidence of CMV infection/disease, recurrence, risk factors, CMV-related mortality, treatment patterns and guidelines, refractory and/or resistant CMV, patient-reported outcomes, and economic burden.

RESULTS

Of 2708 studies identified, 49 were eligible (n = 43/49; 87.8% in adults; n = 34/49, 69.4% in kidney recipients). Across studies, selection of CMV preventive strategy was based on CMV serostatus. Overall, rates of CMV infection (within 1 year) and CMV disease post-SOT were respectively, 10.3%-63.2% (9 studies) and 0%-19.0% (17 studies). Recurrence occurred in 35.4%-41.0% cases (3 studies) and up to 5.3% recipients died of CMV-associated causes (11 studies). Conventional treatments for CMV infection/disease included ganciclovir (GCV) or valganciclovir. Up to 4.4% patients were resistant to treatment (3 studies); no studies reported on refractory CMV. Treatment-related adverse events with GCV included neutropenia (2%-29%), anemia (13%-48%), leukopenia (11%-37%), and thrombocytopenia (13%-24%). Data on economic burden were scarce.

CONCLUSION

Outside of North America and Europe, rates of CMV infection/disease post-SOT are highly variable and CMV recurrence is frequent. CMV resistance and treatment-associated adverse events, including myelosuppression, highlight unmet needs with conventional therapy.

Differential effects of CMV infection on the viability of cardiac cells

Cytomegalovirus (CMV) is a widely prevalent herpesvirus that reaches seroprevalence rates of up to 95% in several parts of the world. The majority of CMV infections are asymptomatic, albeit they have severe detrimental effects on immunocompromised individuals. Congenital CMV infection is a leading cause of developmental abnormalities in the USA. CMV infection is a significant risk factor for cardiovascular diseases in individuals of all ages. Like other herpesviruses, CMV regulates cell death for its replication and establishes and maintains a latent state in the host. Although CMV-mediated regulation of cell death is reported by several groups, it is unknown how CMV infection affects necroptosis and apoptosis in cardiac cells. Here, we infected primary cardiomyocytes, the contractile cells in the heart, and primary cardiac fibroblasts with wild-type and cell-death suppressor deficient mutant CMVs to determine how CMV regulates necroptosis and apoptosis in cardiac cells. Our results reveal that CMV infection prevents TNF-induced necroptosis in cardiomyocytes; however, the opposite phenotype is observed in cardiac fibroblasts. CMV infection also suppresses inflammation, reactive oxygen species (ROS) generation, and apoptosis in cardiomyocytes. Furthermore, CMV infection improves mitochondrial biogenesis and viability in cardiomyocytes. We conclude that CMV infection differentially affects the viability of cardiac cells.

Incidence of cytomegalovirus DNAemia in pediatric kidney, liver, and heart transplant recipients: Efficacy and risk factors associated with failure of weight-based dosed valganciclovir prophylaxis

BACKGROUND

Cytomegalovirus (CMV) is associated with morbidity and mortality in solid organ transplant recipients (SOTR). Valganciclovir (VGC) is extensively used for prophylaxis. Optimal dosing in children, risk factors for failure, and the impact of dose adjustments on CMV DNAemia is not well established.

METHODS

This retrospective cohort study of pediatric SOTR transplanted between 2010-2018 evaluated the epidemiology of CMV DNAemia and used Cox-regression to assess the risk factors for CMV DNAemia within one-year following SOTR.

RESULTS

In 393 pediatric SOTR (heart [96, 24.4%], kidney [180, 45.6%], liver [117, 29.8%]; median age 9.5 ± 0.3 years), overall CMV DNAemia incidence was 6.6/10 000 days (95%CI 5.1/10 000-7.9/10 000) and varied by organ groups: heart 8.2/10 000 days (95%CI 4.9/10 000-11.4/10 000), kidney 5.8/10 000 days (95%CI 3.9/10 000-7.8/10 000), liver 6.2/10 000 days (95%CI 3.7/10 000-8.7/10 000). CMV DNAemia was detected in 75 of 275 (27.2%) patients who received prophylaxis (40 cases occurred during prophylaxis and 35 occurred after completion of prophylaxis). The median VGC dose given according to institutional weight-based algorithm was approximately 1.5-fold lower than the manufacturer-recommended dose. This discordance was more prominent at younger age groups (3.2-fold lower in <2-year-old [100 mg versus 325 mg], 2.5-fold lower in <6-year-old [200 mg versus 447 mg]). Dose reduction due to adverse events was an independent risk factor for breakthrough CMV DNAemia (hazard ratio 2.2, 95%CI 1.2-3.8) among patients with similar age, CMV risk stratification, starting VGC dose, immunosuppressive therapy, and organ group.

CONCLUSION

CMV events occurred while on VGC prophylaxis. Weight-based VGC may prevent supratherapeutic VGC exposure especially in younger children. Dose reduction of VGC prophylaxis for adverse event management places patients at an increased risk for CMV DNAemia suggesting other agents with fewer adverse effects should be considered and need to be studied in children.

Impact of induction therapy on cytomegalovirus infection and post-transplant outcomes in pediatric heart transplant recipients receiving routine antiviral prophylaxis

OBJECTIVES

Induction therapy has been increasingly used in pediatric heart transplantation. This study evaluated the impact of anti-thymocyte globulin (ATG) versus basiliximab as induction therapy on post-transplant cytomegalovirus (CMV) infection, rejection at 1 year, coronary allograft vasculopathy (CAV), and mortality in pediatric heart transplant recipients receiving antiviral prophylaxis.

RESULTS

Of the 96 patients (age < 18 years) analyzed, 46 (47.9%) patients received basiliximab, and 50 (52.1%) received ATG. Median follow-up was 3.0 (IQR, 1.7-4.9) years with 32.3% reporting CMV infection. The ATG group, as compared with the basiliximab group, had similar incidences of CMV infection (36% vs. 28.3%, p = .418), CMV viremia (22% vs. 19.6%, p = .769), and CMV-positive tissue biopsy (30% vs. 22%, p = .486). The ATG group had lower incidences of rejection at 1 year (16% vs. 36.9%, p = .022) and CAV (4% vs. 23.9%, p = .006) with no difference in mortality (8% vs. 15.2%, p = .343), compared with the basiliximab group. Multivariate analysis showed that induction with ATG was associated with a lower risk of rejection at 1 year (OR, .31; 95% CI, .09-.94; p = .039) with no impact on the incidences of CMV infection (HR, 2.06; 95% CI, .54-7.89; p = .292), CAV (HR, .30; 95% CI, .04-2.58; p = .275), and mortality (HR, .39; 95% CI, .09-1.82; p = .233) compared to basiliximab induction.

DISCUSSION AND CONCLUSIONS

In conclusion, induction with ATG was associated with reduction in risk of rejection at 1 year with no effects on CMV infection, CAV, and mortality in pediatric heart transplant recipients with universal antiviral prophylaxis compared with basiliximab induction therapy.

Antiviral toxicities in pediatric solid organ transplant recipients

Prophylaxis with valganciclovir (VGCV) is used routinely to prevent cytomegalovirus (CMV) infections in at-risk pediatric solid organ transplant (SOT) recipients. However, the rate and factors associated with toxicities in this population are not well-described. We conducted a retrospective cohort study of children undergoing SOT at our hospital from January 2012-June 2018. We evaluated the frequency of hematologic and renal toxicities from day 15 through 1-year post-SOT in relation to antiviral exposures, focused on VGCV prophylaxis. Marginal rate models were used to determine the risk of kidney injury and neutropenia in relation to VGCV prophylaxis. Among 281 SOTs, VGCV prophylaxis was administered on 20.1% of all follow-up days. The incidence rates of kidney injury, leukopenia, and neutropenia were significantly higher during VGCV prophylaxis compared to when no antiviral agents were given. Using multivariable marginal rate models, receipt of VGCV prophylaxis was associated with development of kidney injury (rate ratio [RR] 1.79, 95% confidence interval [CI]: 1.22-2.65) and neutropenia (RR 4.82, 95% CI: 3.08-7.55). VGCV dosing did not impact the development of kidney injury or neutropenia. Toxicities are common with VGCV prophylaxis in pediatric SOT recipients.

CMV infection and management among pediatric solid organ transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is an important cause of morbidity and mortality in pediatric solid organ transplant (SOT) recipients. However, the impact of asymptomatic CMV infections (ie, DNAemia) on clinical outcomes is not well established.

METHODS

We performed a retrospective cohort study of children undergoing first SOT at our institution from January 2012 to June 2018. We evaluated the epidemiology of CMV infections and performed multivariable Cox regression to assess the association between CMV DNAemia without disease or CMV disease (syndrome or end-organ disease) on negative outcomes (death, re-transplantation, or moderate/severe rejection) within the first year after SOT.

RESULTS

Among 271 individuals, 43 (15.9%) developed ≥1 CMV infection during the first year after SOT. There were 56 unique CMV infections including 14 episodes of CMV disease. In 167 patients offered CMV prophylaxis, only 8 (4.8%) developed their first CMV DNAemia episode while on prophylaxis 32 developed CMV DNAemia after prophylaxis completion; only 1 episode of CMV disease occurred while on antiviral prophylaxis. When accounting for receipt of ATG, oral steroids, and number of immunosuppressives on a given day, CMV disease was more strongly associated with negative outcomes (Hazard Ratio (HR): 3.28, 95% CI: 0.73-14.64; p = .12) than CMV DNAemia without disease (HR 1.42, 95% CI: 0.19- 10.79; p = .74), although not to a statistically significant degree.

CONCLUSIONS

Most CMV infections occurred after completion of antiviral prophylaxis. CMV disease was more strongly associated with negative outcomes than asymptomatic CMV DNAemia and should be the focus of CMV prevention practices.

Association Between Cytomegalovirus Serostatus, Antiviral Therapy, and Allograft Survival in Pediatric Heart Transplantation

Background: Cytomegalovirus (CMV) is an important complication of heart transplantation and has been associated with graft loss in adults. The data in pediatric transplantation, however, is limited and conflicting. We conducted a large-scale cohort study to better characterize the relationship between CMV serostatus, CMV antiviral use, and graft survival in pediatric heart transplantation.

Methods: 4,968 pediatric recipients of solitary heart transplants from the Scientific Registry of Transplant Recipients were stratified into three groups based on donor or recipient seropositivity and antiviral use: CMV seronegative (CMV-) transplants, CMV seropositive (CMV+) transplants without antiviral therapy, and CMV+ transplants with antiviral therapy. The primary endpoint was retransplantation or death.

Results: CMV+ transplants without antiviral therapy experienced worse graft survival than CMV+ transplants with antiviral therapy (10-year: 57 vs 65%). CMV+ transplants with antiviral therapy experienced similar survival as CMV- transplants. Compared to CMV seronegativity, CMV seropositivity without antiviral therapy had a hazard ratio of 1.21 (1.07–1.37 95% CI, p-value = .003). Amongst CMV+ transplants, antiviral therapy had a hazard ratio of .82 (0.74–.92 95% CI, p-value < .001). During the first year after transplantation, these hazard ratios were 1.32 (1.06–1.64 95% CI, p-value .014) and .59 (.48–.73 95% CI, p-value < .001), respectively.

Conclusions: CMV seropositivity is associated with an increased risk of graft loss in pediatric heart transplant recipients, which occurs early after transplantation and may be mitigated by antiviral therapy.

Epidemiology and long-term outcomes of cytomegalovirus DNAemia and disease in pediatric solid organ transplant recipients

Despite prevention strategies, cytomegalovirus (CMV) remains a common infection in pediatric solid organ transplant recipients (SOTR). We sought to determine the frequency, associations with, and long-term outcomes of CMV DNAemia in pediatric SOTR. We performed a single-center retrospective cohort study, including 687 first time SOTR ≤21 years receiving universal prophylaxis from 2011 to 2018. Overall, 159 (23%) developed CMV DNAemia, the majority occurring after completing primary prophylaxis. CMV disease occurred in 33 (5%) SOTR, 25 (4%) with CMV syndrome and 10 (1%) with proven/probable tissue-invasive disease. CMV contributed to the death of three (0.4%) patients (all lung). High-risk (OR 6.86 [95% CI, 3.6-12.9]) and intermediate-risk (4.36 [2.3-8.2]) CMV status and lung transplantation (4.63 [2.33-9.2]) were associated with DNAemia on multivariable analysis. DNAemia was associated with rejection in liver transplant recipients (p < .01). DNAemia was not associated with an increase in graft failure, all-cause mortality, or other organ-specific poor outcomes. We report one of the lowest rates of CMV disease after SOTR, showing that universal prophylaxis is effective and should be continued. However, we observed CMV morbidity and mortality in a subset of patients, highlighting the need for research on optimal prevention strategies. This study was IRB approved.