Safety and tolerability of cidofovir in high-risk pediatric patients

Cidofovir for Viral Infections in Immunocompromised Children: Guidance on Dosing, Safety, Efficacy, and a Review of the Literature

OBJECTIVE

To describe the use of cidofovir (CDV) for viral infections in immunocompromised children (IC) and provide guidance on dosing and supportive care.

DATA SOURCES

A PubMed search was conducted for literature published between 1997 and January 2022 using the following terms: cidofovir, plus children or pediatrics.

STUDY SELECTION AND DATA EXTRACTION

Limits were set to include human subjects less than 24 years of age receiving intravenous (IV) or intrabladder CDV for treatment of infections due to adenovirus, polyomavirus-BK (BKV), herpesviruses, or cytomegalovirus.

DATA SYNTHESIS

Data were heterogeneous, with largely uncontrolled studies. Conventional dosing (CDV 5 mg/kg/dose weekly) was commonly used in 60% (31/52) of studies and modified dosing (CDV 1 mg/kg/dose 3 times/week) was used in 17% (9/52) of studies, despite being off-label. Nephrotoxicity reported across studies totaled 16% (65/403 patients), which was higher for conventional dosing 29 of 196 patients (15%) than modified dosing 1 of 27 patients (4%). Saline hyperhydration and concomitant probenecid remain the cornerstones of supportive care, while some regimens omitting probenecid are emerging to target BKV.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

To our knowledge, this is the first comprehensive review of CDV use (indications, dosing, supportive care, response, and nephrotoxicity) in pediatric IC.

CONCLUSIONS

Effective utilization of CDV in IC remains challenging. Further prospective studies are needed to determine the optimal CDV dosing; however, less aggressive dosing regimens such as modified thrice weekly dosing or low dosing once weekly omitting probenecid to enhance urinary penetration may be reasonable alternatives to conventional dosing in some IC.

Adenovirus Infection and Transplantation

Adenoviruses result in a wide array of clinical presentations, including primarily respiratory, gastrointestinal, genitourinary, or systemic infections. Although adenovirus causes mild disease limited to a single organ system in immunocompetent individuals, severe and life-threatening infections do rarely occur. Disseminated disease and severe localized disease resulting in significant morbidity and mortality have been well described in the immunocompromised populations. Although asymptomatic viremia, respiratory tract, and gastrointestinal infections are the most common disease in most transplant patients, renal transplant patients more commonly experience urinary tract infections, including hemorrhagic cystitis or nephritis. Diagnosis requires astute clinical awareness of the patient's clinical presentation that would be compatible with adenovirus combined with cultures, molecular testing, polymerase chain reaction, and tissue sampling. There is no Food and Drug Administration-approved treatment for adenovirus; however, several studies have evaluated therapeutic options including cidofovir, brincidofovir, and immunotherapy. This article will summarize our current understanding of adenovirus in the transplant population.

Epidemiology of Adenovirus Infections and Outcomes of Cidofovir Treatment in Severely Ill Children

BACKGROUND

An increase in human adenovirus (HAdV) infections among hospitalized children in Singapore was observed since 2013. Young age (<2 years) and significant comorbidities have been associated with severe HAdV infections which can result in significant morbidity and mortality. Cidofovir (CDV) has been used to treat severe HAdV infections despite limited data and efficacy.

METHODS

This is a retrospective, observational review of infants and children 1 month to 17 years of age with laboratory-confirmed severe HAdV infection, admitted to a pediatric tertiary care hospital in Singapore between January 2013 and September 2017. Severe infection was defined as requiring intensive care unit or high dependency care at any point during hospital admission. Clinical characteristics, potential risk factors for mortality, as well as the outcome of cases treated with CDV were examined.

RESULTS

A total of 1167 children were admitted for HAdV infection, of which 85 (7.3%) were severe. For severe infections, the median age was 1.5 years (interquartile range: 0.72-3.2 years). The majority had comorbidities (69.4%) and presented with pneumonia (32.9%). Genotypes HAdV-7 (29.4%) and HAdV-3 (27.0%) were the most common HAdV genotypes identified. Thirteen (15.3%) patients died. Patients who died had a higher proportion of existing neurologic comorbidity (46.2% vs. 13.9%; P = 0.014) and presentation with pneumonia (69.2% vs. 26.4%; P = 0.008) compared with survivors. Patients who presented with pneumonia had a higher risk of 30-day mortality (odds ratio 4.3, 95% confidence interval: 1.0-28.6; P < 0.05). CDV was administered to 17 (20%) children for mainly viremia (47.1%) and/or pneumonia (41.2%). Mortality rate was 41.2% for severe HAdV cases treated with CDV. A significant proportion of patients who died when compared with recovered patients presented with pneumonia (6 of 7, 85.7% vs 1 of 10, 10%; P = 0.004). All 8 patients who had viremia received CDV and survived.

CONCLUSIONS

Mortality can be high in pediatric patients with severe HAdV infections. HAdV-7 and HAdV-3 were the most common genotypes identified in our cohort with severe HAdV infection. Pneumonia is a potential risk factor for mortality in severe HAdV infections in our cohort. Early CDV administration may be considered in patients with severe HAdV infection and existing comorbidities but more studies are required.

Approach to infection and disease due to adenoviruses in solid organ transplantation

PURPOSE OF REVIEW

Adenoviruses are an important cause of morbidity and mortality of solid organ transplant patients and remain a clinical challenge with regard to diagnosis and treatment. In this review, we provide an approach to identification and classification of adenovirus infection and disease, highlight risk factors, and outline management options for adenovirus disease in solid organ transplant patients.

RECENT FINDINGS

Additional clinical data and pathologic findings of adenovirus disease in different organs and transplant recipients are known. Unlike hematopoietic cell transplant recipients, adenovirus blood PCR surveillance and preemptive therapy is not supported in solid organ transplantation. Strategies for management of adenovirus disease continue to evolve with newer antivirals, such as brincidofovir and adjunctive immunotherapies, but more studies are needed to support their use.

SUMMARY

Distinguishing between adenovirus infection and disease is an important aspect in adenovirus management as treatment is warranted only in symptomatic solid organ transplant patients. Supportive care and decreasing immunosuppression remain the mainstays of management. Cidofovir remains the antiviral of choice for severe or disseminated disease. Given its significant nephrotoxic effect, administration of probenecid and isotonic saline precidofovir and postcidofovir infusion is recommended.

ATO (Arsenic Trioxide) Effects on Promyelocytic Leukemia Nuclear Bodies Reveals Antiviral Intervention Capacity

Human adenoviruses (HAdV) are associated with clinical symptoms such as gastroenteritis, keratoconjunctivitis, pneumonia, hepatitis, and encephalitis. In the absence of protective immunity, as in allogeneic bone marrow transplant patients, HAdV infections can become lethal. Alarmingly, various outbreaks of highly pathogenic, pneumotropic HAdV types have been recently reported, causing severe and lethal respiratory diseases. Effective drugs for treatment of HAdV infections are still lacking. The repurposing of drugs approved for other indications is a valuable alternative for the development of new antiviral therapies and is less risky and costly than de novo development. Arsenic trioxide (ATO) is approved for treatment of acute promyelocytic leukemia. Here, it is shown that ATO is a potent inhibitor of HAdV. ATO treatment blocks virus expression and replication by reducing the number and integrity of promyelocytic leukemia (PML) nuclear bodies, important subnuclear structures for HAdV replication. Modification of HAdV proteins with small ubiquitin-like modifiers (SUMO) is also key to HAdV replication. ATO reduces levels of viral SUMO-E2A protein, while increasing SUMO-PML, suggesting that ATO interferes with SUMOylation of proteins crucial for HAdV replication. It is concluded that ATO targets cellular processes key to HAdV replication and is relevant for the development of antiviral intervention strategies.

Broad-spectrum antiviral activity of the deubiquitinase inhibitor HBX against human adenoviruses

BACKGROUND

Human adenoviral (HAdV) infections are usually mild and self-limited, however, some infections from species A, B, C, D and E, can cause severe illnesses, which have raised public health concerns over the past few years. Current available antiviral therapies have limited efficacy and severe toxicity; therefore, finding new targets for specific anti-adenoviral drug design is urgently needed. Our previous work showed that the small molecule compound, HBX, inhibits HAdV type 5 (species C, HAdV-C5) replication and oncogenic transformation through inhibition of the cellular pro-viral factor ubiquitin-specific protease 7 (USP7). Here, we have tested the ability of HBX to inhibit other HAdV species, as well as different clinical isolates that are the cause of severe infections.

METHODS

We treated HAdV-infected A549 cells with different concentrations of HBX and analysed the antiviral efficacy of the drug by determining the half maximal inhibitory concentration (IC50) necessary to decrease both viral genome copies and virus progeny production at different time points after infection.

RESULTS

In addition to its effect on HAdV-C5, HBX was able to significantly inhibit virus genome replication and progeny release of all adenovirus types tested, with the exception of types 12 and 31, from species A. Of note, clinical isolates were more sensitive to HBX treatment than their prototype strains.

CONCLUSIONS

These results point to HBX as a promising broad-spectrum anti-adenoviral drug, opening new opportunities to prevent severe adenoviral infections and to improve their treatment.

The yield of monitoring adenovirus in pediatric hematopoietic stem cell transplant patients

Human adenovirus (HAdV) is recognized as a serious pathogen after allogeneic hematopoietic stem cell transplantation (HSCT), causing morbidity and mortality. Currently, there is no universal agreement regarding routine HAdV surveillance after HSCT. We assessed the impact of HAdV weekly monitoring by polymerase chain reaction (PCR) on HAdV viremia rates and the risk factors that influence survival. Three-hundred and fifty-six pediatric allogeneic HSCT were done between 2007 and 2015. Until July 2011, HAdV testing was performed based on clinical suspicion (cohort 1, n = 175) and from August 2011, weekly blood-HAdV monitoring was done (cohort 2, n = 181) until day +100. Twenty-three patients (4 [2.3%] from cohort 1 and 19 [10.5%] from cohort 2, p = .001) were found with HAdV viremia and seven of them died. Both cohorts had a similar incidence of HAdV-associated mortality (3/175; 1.7% in cohort 1 and 4/181; 2.2% in cohort 2). Respiratory failure was the cause of death in all patients. Clinical symptoms appeared prior to or within 5 days of HAdV detection in cohort 2. In summary, weekly monitoring was associated with higher detection of HAdV. The study could not assess survival benefit due to small numbers of HAdV-positive cases. In many instances, symptoms occurred with the development of positive HAdV blood PCR results and hence, symptomatology could have triggered the test. Future studies are needed to provide data that help establishing a uniform approach for regular monitoring of HAdV post-transplant.

Virologic response with 2 different cidofovir dosing regimens for preemptive treatment of adenovirus DNAemia in pediatric solid organ transplant recipients

ADV is frequently seen in our pediatric SOT population. It presents in a variety of clinical presentation and can cause severe disease. In this population, there are very few studies to determine the safety of CDV as a potential therapeutic agent. We present the findings of our retrospective study evaluating the efficacy and safety of CDV as 2 separate dosing regimens. Regimen A uses the standard 5 mg/kg once a week (Regimen A), and the second uses the 1 mg/kg 3 times per week (Regimen B). Overall, the dosing regimen did not differ in nephrotoxicity, but Regimen B had a higher, although non-significant, rate of viral load clearance. This suggests that more frequent dosing at lower levels may be more efficacious without any significant side effects in our SOT population.

Management of adenovirus infection in patients after haematopoietic stem cell transplantation: State-of-the-art and real-life current approach: A position statement on behalf of the Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation

The important insights gained over the past years in diagnosis and treatment of invasive adenoviral infections provide new paradigms for the monitoring and clinical management of these life-threatening complications. A meeting was held to discuss and subsequently disseminate the current advances in our understanding of the aetiology/pathogenesis and future treatment options facilitating effective control or prevention of adenovirus-related diseases in the allogeneic haematopoietic stem cell transplant setting. Invited experts in the field discussed recent progress with leading members of the Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation at the "State-of-the-art" Meeting in Poznan, Poland, in October 2017. In this review article, the panel of experts presents a concise summary of the current evidence based on published data from the last 15 years and on recent achievements resulting from real-life practice. The present position statement reflects an expert opinion on current approaches to clinical management of adenovirus infections in patients undergoing allogeneic haematopoietic stem cell transplant and provides graded recommendations of the panel for diagnostic approaches and preemptive therapy reflecting the present state of knowledge.

Renal Toxicity in Pediatric Patients Receiving Cidofovir for the Treatment of Adenovirus Infection

Treatment options for adenovirus infection in immunocompromised children are limited. Nephrotoxicity has been associated with cidofovir use, but the rate of cidofovir-associated nephrotoxicity in pediatric patients is unclear. In a retrospective review of patients with adenovirus infection treated with cidofovir, neonates (n = 5) had higher viral loads and shorter times to renal insufficiency than older children (n = 24). Higher weekly doses of cidofovir were associated with greater increases in creatinine levels. Of 29 courses of cidofovir, 9 were complicated by acute kidney injury; in these children, mortality was high. Cidofovir dosing in children needs to be optimized, and other therapeutic alternatives should be developed.

Adenovirus: Epidemiology, Global Spread of Novel Serotypes, and Advances in Treatment and Prevention

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe and dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue tropisms that correlate with clinical manifestations of infection. The predominant serotypes circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been conducted. Cidofovir is the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States, but currently are not available to civilians.

Use of cidofovir in pediatric patients with adenovirus infection

Background: Adenoviruses contribute to morbidity and mortality among immunocompromised pediatric patients including stem cell and solid organ transplant recipients. Cidofovir (CDV), an antiviral compound approved by the FDA in 1996, is used for treatment of adenoviral (ADV) infections in immunocompromised patients despite concern of potential nephrotoxicity.   Methods: We conducted a retrospective 5-year review at Boston Children's Hospital of 16 patients (mean age = 6.5 years) receiving 19 courses of CDV. During therapy all pertinent data elements were reviewed to characterize potential response to therapy and incidence of renal dysfunction.   Results: Of the 19 CDV courses prescribed, 16 courses (84%) were in patients who had a positive blood ADV Polymerase chain reaction (PCR) alone or in combination with positive ADV PCR/ Direct Immunofluorescence Assay (DFA) at another site. Respiratory symptoms with or without pneumonia were the most common presentation (10/19, 53%). In the majority of blood positive courses (10/16, 63%), viral clearance was also accompanied by clinical response. This was not the case in four courses where patients expired despite viral clearance, including one in which death was directly attributable to adenovirus. There was reversible renal dysfunction observed during the use of CDV. Conclusions:  CDV appeared safe and reasonably tolerated for treatment of ADV in this pediatric population and was associated with viral response and clinical improvement in the majority of patients but reversible renal dysfunction was a side effect. Further studies of the efficacy of CDV for immunocompromised children with ADV infection are warranted.

Use of cidofovir in pediatric patients with adenovirus infection

Background: Adenoviruses contribute to morbidity and mortality among immunocompromised pediatric patients including stem cell and solid organ transplant recipients. Cidofovir (CDV), an antiviral compound approved by the FDA in 1996, is used for treatment of adenoviral (ADV) infections in immunocompromised patients despite concern of potential nephrotoxicity.   Methods: We conducted a retrospective 5-year review at Boston Children's Hospital of 16 patients (mean age = 6.5 years) receiving 19 courses of CDV. During therapy all pertinent data elements were reviewed to characterize potential response to therapy and incidence of renal dysfunction.   Results: Of the 19 CDV courses prescribed, 16 courses (84%) were in patients who had a positive blood ADV Polymerase chain reaction (PCR) alone or in combination with positive ADV PCR/ Direct Immunofluorescence Assay (DFA) at another site. Respiratory symptoms with or without pneumonia were the most common presentation (10/19, 53%). In the majority of blood positive courses (10/16, 63%), viral clearance was also accompanied by clinical response. This was not the case in four courses where patients expired despite viral clearance, including one in which death was directly attributable to adenovirus. There was reversible renal dysfunction observed during the use of CDV. Conclusions:  CDV appeared safe and reasonably tolerated for treatment of ADV in this pediatric population and was associated with viral response and clinical improvement in the majority of patients but reversible renal dysfunction was a side effect. Further studies of the efficacy of CDV for immunocompromised children with ADV infection are warranted.

Antiadenovirus drug discovery: potential targets and evaluation methodologies

Human adenoviruses (HAdV) are the cause of many acute infections, mostly in the respiratory and gastrointestinal (GI) tracts, as well as conjunctivitis. HAdV diseases in immunocompetent individuals are mostly self-limiting; however, in immunocompromised individuals, especially in pediatric units, HAdV infections are the cause of high morbidity and mortality. Despite the significant clinical impact, there are currently no approved antiviral therapies for HAdV infections. Here, we provide an overview of the different targets that could be considered for the design of specific drugs against HAdV, as well as the available in vitro and in vivo tools for the screening and evaluation of candidate molecules.

Significant Transplantation-Related Mortality from Respiratory Virus Infections within the First One Hundred Days in Children after Hematopoietic Stem Cell Transplantation

Respiratory viral infections (RVI) are important in hematopoietic stem cell transplantations (HSCT) and knowledge regarding incidence, morbidity, mortality, and long-term pulmonary complications is limited. We report a study to evaluate incidence and outcomes, both short and long-term, of RVI in children receiving HSCT. Between January 2000 and December 2012, 844 patients underwent hematopoietic stem cell transplantation (HSCT) at the Hospital for Sick Children: 491 were allogeneic and 353 were autologous. When screening for causes of death in the first year after HSCT in the 844 patients, we found that RVI as a cause of death was only evident in the first 100 days after HSCT. Fifty-four (6.5%) patients were found to have an RVI within the first 100 days after HSCT (allogeneic = 32, autologous = 22). Upper and lower respiratory tract infections were documented in 31 (57%) and 23 (43%) patients, respectively. Viruses were parainfluenza (35%), respiratory syncytial virus (28%), influenza (22%), adenovirus (7%), human metapneumovirus (4%), coronavirus (2%), and rhinovirus (2%). Three patients relapsed with their primary disease before day 100 and were excluded. The overall mortality for the remaining 51 patients was 10% (allogeneic = 4, autologous = 1). All 5 deaths were directly attributable to RVI and all 5 deaths occurred in patients with a lower respiratory tract infection. The remaining patients were followed for a median of 4.3 years (range, 1.4 to 11.8) and no chronic pulmonary complications were observed. A clear seasonal pattern for contracting RVI was evident with 65% of total RVI occurring between October and March (35 of 427 versus 19 of 417, P = .03). Given the significant mortality from RVI and the challenges in preventing them, choosing the time to start HSCT, whenever possible, may help prevent RVI and improve outcomes.

Successful Treatment of Disseminated Adenovirus Infection in an Infant With Acute Lymphoblastic Leukemia

Systemic adenovirus infection in the immunocompromised host is often fatal and therapeutic options are limited. We report an infant with acute lymphoblastic leukemia who developed disseminated adenovirus infection while lymphopenic during maintenance chemotherapy 6 months following a bout of adenoviral diarrhea. His serum adenoviral load peaked at 35 million copies/mL and was associated with pancytopenia and hepatic injury. Treatment with cidofovir was effective although associated with mild renal injury. The patient recovered fully and completed chemotherapy for infant acute lymphoblastic leukemia.

Pharmacokinetics and safety of intravenous cidofovir for life-threatening viral infections in pediatric hematopoietic stem cell transplant recipients

Children undergoing hematopoietic stem cell transplantation (HSCT) are at risk for life-threatening viral infections. Cidofovir is often used as a first-line agent for adenovirus infections, despite the absence of randomized controlled trials with HSCT patients, and as a second-line agent for resistant herpesvirus infections. The frequency and severity of adverse effects, particularly nephrotoxicity, in pediatric HSCT recipients are unclear, and pharmacokinetics (PK) of cidofovir in children have not previously been reported. This study was an open-label, nonrandomized, single-dose pilot study to determine the safety and PK of cidofovir in pediatric HSCT recipients with symptomatic adenovirus, nucleoside-resistant cytomegalovirus (CMV) or herpes simplex virus (HSV), and/or human papovavirus infections. Subsequent dosing and frequency were determined by clinical response and side effects, as assessed by the treating physician. Blood and urine samples were obtained from patients for PK studies and assessment of toxicity and virologic response. Twelve patients were enrolled (median age, 9 years; 33.5 days posttransplantation). Four of seven patients with adenovirus infection were successfully treated and eventually cleared their infections. Four of twelve patients died of disseminated viral disease and multiorgan failure. Two of twelve patients had evidence of acute kidney injury after the first dose, and one of these patients developed chronic kidney disease; two other patients developed late nephrotoxicity. The mean drug half-life was 9.5 h. There was no correlation between nephrotoxicity and plasma maximum concentration, clearance, or half-life. PK were similar to those reported for adults, although the drug half-life was significantly longer than that for adults. Cidofovir was well tolerated in the majority of patients. However, effective therapeutic strategies are urgently needed to support patients until immune reconstitution is achieved.

Adenovirus infections in immunocompetent and immunocompromised patients

Human adenoviruses (HAdVs) are an important cause of infections in both immunocompetent and immunocompromised individuals, and they continue to provide clinical challenges pertaining to diagnostics and treatment. The growing number of HAdV types identified by genomic analysis, as well as the improved understanding of the sites of viral persistence and reactivation, requires continuous adaptions of diagnostic approaches to facilitate timely detection and monitoring of HAdV infections. In view of the clinical relevance of life-threatening HAdV diseases in the immunocompromised setting, there is an urgent need for highly effective treatment modalities lacking major side effects. The present review summarizes the recent progress in the understanding and management of HAdV infections.

Viral infections in acute graft-versus-host disease: a review of diagnostic and therapeutic approaches

BACKGROUND

While immunosuppressive therapy for acute graft-versus-host disease (aGVHD) advances, viral reactivation has been found to be an increasingly common complication in these patients. Dermatologists may often be consulted on inpatient services for evaluation.

OBJECTIVE

We investigated the literature for the role of viral infections in aGVHD and review the current evidence regarding management.

METHODS

Articles in the public domain regarding aGVHD, cytomegalovirus, Epstein-Barr virus, varicella zoster virus, hepatitis viruses, parvovirus B19, and respiratory viruses were included.

RESULTS

Dermatologic findings vary between different viral antigens, and some infections may be a marker for the development of aGVHD or worsen prognosis.

LIMITATIONS

The heterogeneous cohorts of the studies reviewed often preclude direct comparison between results.

CONCLUSION

The relationship between viral reactivation and aGVHD may be bidirectional and is worthy of further exploration. Additional studies are needed to determine appropriate prophylaxis and treatment.

Cidofovir in pediatric solid organ transplant recipients: University of Nebraska experience

BACKGROUND

Clinical experience with cidofovir in pediatric solid organ transplantation is limited. We assessed the effect of cidofovir use on renal function in pediatric solid organ transplant recipients.

METHODS

Wilcoxon signed-rank tests were used to determine if changes in renal function were significant, Wilcoxon rank-sum tests to test the association between changes in glomerular filtration rate and potential confounding factors, and MacNemar tests to compare the proportions of patients at different time points.

RESULTS

We included 25 patients with a mean age of 4.2 years (SD 4.6). More patients were receiving renal replacement therapy while being treated with cidofovir compared with baseline (24% vs. 4%; P = 0.03). For patients not receiving renal replacement therapy, there was no evidence of a significant median change in glomerular filtration rate from baseline to 1 month after cidofovir treatment (P = 0.32) or to the end of cidofovir treatment (P = 0.23) or in creatinine from baseline to the end of cidofovir therapy (P = 0.2). There was a marginal decreased median change in creatinine from baseline to 1 month after cidofovir treatment (P = 0.06). Fewer patients had proteinuria (72.2% vs. 27.8%; P = 0.02) and hematuria (22.2% vs. 0%) after cidofovir treatment.

CONCLUSION

In our pediatric transplant cohort, cidofovir did not significantly change renal function reflected by creatinine, glomerular filtration rate, hematuria or proteinuria, but a significant number of patients required renal replacement therapy because of fluid overload.

The effect of cidofovir on adenovirus plasma DNA levels in stem cell transplantation recipients without T cell reconstitution

Cidofovir is frequently used to treat life-threatening human adenovirus (HAdV) infections in immunocompromised children after hematopoietic stem cell transplantation (HSCT). However, the antiviral effect irrespective of T cell reconstitution remains unresolved. Plasma HAdV DNA levels were monitored by real-time quantitative PCR during 42 cidofovir treatment episodes for HAdV viremia in 36 pediatric allogeneic HSCT recipients. HAdV load dynamics were related to T and natural killer (NK) cell reconstitution measured by flow cytometry. To evaluate the in vivo antiadenoviral effect of cidofovir, we focused on 20 cidofovir treatment episodes lacking concurrent T cell reconstitution. During 2 to 10 weeks of follow-up in the absence of T cells, HAdV load reduction (n = 7) or stabilization (n = 8) was observed in 15 of 20 treatments. Although HAdV load reduction was always accompanied by NK cell expansion, HAdV load stabilization was measured in 2 children lacking both T and NK cell reconstitution. In cases with T cell reconstitution, rapid HAdV load reduction (n = 14) or stabilization (n = 6) was observed in 20 of 22 treatments. In the absence of T cells, cidofovir treatment was associated with HAdV viremia control in the majority of cases. Although the contribution of NK cells cannot be excluded, cidofovir has the potential to mediate HAdV load stabilization in the time pending T cell reconstitution.

Advances in antivirals for non-influenza respiratory virus infections

Progress in the development of antivirals for non‐influenza respiratory viruses has been slow with the result that many unmet medical needs and few approved agents currently exist. This commentary selectively reviews examples of where specific agents have provided promising clinical benefits in selected target populations and also considers potential therapeutics for emerging threats like the SARS and Middle East respiratory syndrome coronaviruses. Recent studies have provided encouraging results in treating respiratory syncytial virus infections in lung transplant recipients, serious parainfluenza virus and adenovirus infections in immunocompromised hosts, and rhinovirus colds in outpatient asthmatics. While additional studies are needed to confirm the efficacy and safety of the specific agents tested, these observations offer the opportunity to expand therapeutic studies to other patient populations.

Adenovirus pneumonia presenting with nodular shadows on chest X-ray in two unrelated allogeneic bone marrow transplant recipients

Adenoviruses are increasingly recognized as important pathogens following allogeneic stem cell transplantation. We herein report two cases of disseminated adenovirus infection that presented with nodular shadows on chest X-ray after allogeneic bone marrow transplantation from unrelated donors. Both patients died of respiratory failure. Autopsies revealed adenovirus infection of multiple organs. Adenovirus infection should be suspected when nodular lung lesions of unknown origin appear in allogeneic stem cell transplant recipients.

Patient, virus, and treatment-related risk factors in pediatric adenovirus infection after stem cell transplantation: results of a routine monitoring program

Human adenovirus (HAdV) infection after hematopoietic stem cell transplantation (HSCT) is associated with significant morbidity and mortality in children. The optimal surveillance and treatment strategies are under discussion. Here, we present data from 238 consecutive pediatric allogeneic HSCT recipients who underwent transplantation in a single center who were included in a prospective, weekly HAdV DNAemia monitoring program by quantitative PCR. HAdV loads >1000 copies/mL were detected in 15.5% of all patients. Despite a low mortality directly attributed to HAdV infection (2 patients, 0.84%), blood HAdV loads >10,000 copies/mL (6.7% of all patients) were significant and independent risk factors for poor survival. We searched for patient, virus, and treatment-related risk factors of HAdV DNAemia and disease. Detection of HAdV in blood before day 50 post transplantation was a major independent risk factor for the development of blood HAdV loads >10,000 copies/mL. HAdV typing revealed A31, C1, and C2 as the predominant pathogens among several other HAdV strains with type C species detected in most patients with severe HAdV disease. Stool HAdV loads were prospectively monitored in 111 patients and correlated with but did not significantly precede detection in blood. Treatment with cidofovir led to stable or reduced viral load in 70% of patients with blood HAdV loads >1000 copies/mL. Thus, early occurrence of HAdV-DNA in blood of pediatric HSCT recipients predisposes for development of high viral loads. Control of HAdV infections was attempted by preemptive cidofovir treatment of patients with high blood HAdV loads or with symptomatic organ infections and correlated with low HAdV-attributed mortality.

Diagnosis and treatment of adenovirus infection in immunocompromised patients

In immunocompromised patients, human adenovirus (HAdV) infections can cause life-threatening multiorgan disease. This review summarizes the incidence and risk factors of invasive human adenovirus infections in immunocompromised patients as well as the recently developed standards for diagnostic methods and strategies according to the predominant risk factors in adults and children. Recommendations for preemptive and therapeutic treatment strategies and the outcome in different risk groups are presented. Novel therapeutic approaches including CMX001, a new orally bioavailable lipid conjugate of cidofovir and the transfer of adenovirus-specific donor T cells in the context of allogeneic stem cell transplantation are discussed.

Case report: severe disseminated adenovirus infection in a neonate following water birth delivery

Adenovirus infections are a common cause of respiratory and enteric illnesses of late infancy and childhood. In neonates, adenovirus infections are rare, carrying a high morbidity and mortality rate. We present a case of infant who developed severe pneumonia and disseminated adenoviral infection following water birth delivery to a mother with gastroenteritis. The infant's infection was due to an adenovirus strain that has not been previously reported in neonates.

Adenovirus viremia and disease: comparison of T cell-depleted and conventional hematopoietic stem cell transplantation recipients from a single institution

Adenovirus (ADV) is an important cause of viral mortality in hematopoietic stem cell transplantation (HSCT). Recipients of T cell-depleted (TCD) HSCT are at increased risk for viral infections. We compared the rates and outcomes of ADV viremia and disease between TCD and conventional (CONV) HSCT at our institution. This was an observational study of 624 adult and pediatric recipients of myeloablative HSCT at Memorial Sloan-Kettering Cancer Center between January 1, 2006, and March 11, 2011. Viral cultures and ADV PCR were ordered as clinically indicated. ADV viremia by quantitative PCR assay was defined as 1 or more positive values ≥1,000 copies/mL or 2 or more consecutive positive values. Competing-risk regression analyses were used to identify predictors for ADV viremia. ADV viremia at 1 year after HSCT occurred in 8% of TCD HSCT recipients and in 4.0% of CONV HSCT recipients (P = .041). Among the TCD recipients, ADV viremia was seen in 15% of children, compared with 5% of adults (P = .008). Young age (hazard ratio [HR], 3.0; P < .001) and acute graft-versus-host disease (GVHD) (HR, 3.2; P = .001) were identified as risk factors for ADV viremia. ADV viremia was predictive of mortality (HR, 6.0; P < .001). ADV disease developed in 3.5% of TCD HSCT recipients and in 0.4% of CONV HSCT recipients (P = .022), with an attributable mortality of 27%. Among TCD HSCY recipients, grade II to IV GVHD was a risk factor for ADV disease (HR, 13; P < .001), but age was not. More than 90% of the cases of ADV disease involved a viral load of ≥10,000 copies/mL. Rates of ADV disease were 10-fold greater in TCD HSCT recipients compared with CONV HSCT recipients, predominantly in patients who developed acute GVHD. The benefit of preemptive therapy for an ADV viral load ≥10,000 copies/mL for preventing ADV disease in TCD HSCT recipients should be evaluated in prospective clinical trials.

Successful response to cidofovir of adenovirus hepatitis during chemotherapy in a child with hepatoblastoma

BACKGROUND

Adenoviral infections are endemic in the pediatric population. Most of these infections are mild and self-limited in immunocompetent individuals. Although in profoundly immunocompromised hosts after solid organ or stem cell transplantation, adenovirus may cause fulminant hepatitis or other life-threatening infections, this is a rare complication in patients receiving standard chemotherapy.

OBSERVATION

We report a case of severe adenovirus hepatitis in a 7-month-old child receiving induction chemotherapy for hepatoblastoma who fully recovered after treatment with cidofovir.

CONCLUSIONS

To our knowledge, this is the first report documenting recovering of severe adenoviral hepatitis in a nontransplanted immunocompromised host.

Molecular diagnosis and management of viral infections in hematopoietic stem cell transplant recipients

Viral infections after allogeneic hematopoietic stem cell transplantation (HSCT) are important complications associated with high morbidity and mortality. In this setting, reactivations of persisting latent viral pathogens from donor and/or recipient cells play a central role whereas the sterile environment of transplant units renders new infections less likely. The viruses currently regarded as most relevant in the HSCT setting include particularly the herpes virus family--specifically cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV-6)--as well as human adenoviruses (AdVs) and the polyoma virus BK (BKV). Timely detection and monitoring of virus copy numbers are prerequisites for successful preemptive treatment approaches. Pre- and post-transplant surveillance by sensitive and quantitative molecular methods has therefore become an essential part of the diagnostic routine. In this review, we discuss diagnostic aspects and the clinical management of the most important viral infections in HSCT recipients, with a focus on pediatric patients.

Management of refractory hemorrhagic cystitis following hematopoietic stem cell transplantation in children

HC is a complication associated with HSCT, but occurs rarely in solid organ recipients. The reported incidence varies from <10% to more than 70%. HC is characterized by hemorrhagic inflammation in urinary tract mucosa with symptoms varying from asymptomatic microscopic hematuria to frank hematuria with clot formation and urinary tract obstruction. Early onset HC may be explained by toxicity of chemo- and/or radiotherapy, while multiple factors including viral infections and their interplay seem to be involved in late onset HC. So far, only incidence of cyclophosphamide-associated HC has been reduced with preventive treatment. Likely, once HC is established, the treatment principles are similar regardless of the etiology and depend on the intensity of HC. Prevention of urinary tract obstruction, transfusion support, analgesic, and spasmolytic therapy are generally accepted in HC management. Treatment beyond this conservative approach entails higher risk for side effects, and thus treatment escalation proportional to HC intensity is warranted. No standard and evidence-based treatment escalation algorithm has been widely adopted yet. As severe HC following HSCT is a potentially life-threatening complication, a multidisciplinary and individual approach is required in children suffering from this devastating complication.

How I treat adenovirus in hematopoietic stem cell transplant recipients

Adenovirus (AdV) infections are very common in the general pediatric population. The delayed clearance in young persons imposes a threat to immunocompromised patients after hematopoietic stem cell transplantation (HSCT), who can reactivate the virus, resulting in life-threatening disseminated disease. Although a definitive cure requires adequate immune reconstitution, 2 approaches appear to be feasible and effective to improve the outcomes of AdV infections. Strict monitoring with AdV quantitative polymerase chain reaction followed by preemptive treatment with low-dose (1 mg/kg) cidofovir 3 times a week, is effective in most cases to bridge the severely immunocompromised period shortly after HSCT, with acceptable toxicity rates. For centers who have the access, AdV-specific cytotoxic T cells can be the other important cornerstone of anti-AdV therapy with promising results so far. Methods to positively influence the reconstitution of the immune system after HSCT and optimizing new and currently available cellular immunotherapies will make HSCT safer against the threat of AdV infection/reactivation and associated disease.

Evaluation of a surveillance strategy for early detection of adenovirus by PCR of peripheral blood in hematopoietic SCT recipients: incidence and outcome

Adenoviruses (AdV) have emerged as important causes of morbidity and mortality in patients after hematopoietic SCT (HSCT). Early diagnosis of the infection by detection of viral DNA may improve the prognosis. A surveillance strategy was evaluated for detection of AdV DNA by PCR in a prospective study of unselected allogeneic HSCT recipients. In parallel with a routine CMV surveillance program, plasma from 20 children and 77 adults was analyzed by quantitative PCR for detection of AdV DNA. In addition, in 12 unselected patients, the presence of AdV-specific T cells were analyzed by enzyme-linked immunosorbent spot (ELISPOT) at 1 to 3 months after transplantation. A total of 5 of 97 (5%) patients had detectable AdV DNA in peripheral blood. Only one patient had high titers and none developed AdV disease. BM as a source of stem cells and myelodysplastic syndrome as the indication for transplantation were independently associated with higher risk of acquiring AdV infection. AdV-specific T cells were detected in 7 (58%) of 12 patients. Although AdV DNA was found in peripheral blood by quantitative PCR in 5% of patients undergoing allogeneic HSCT, the present surveillance program did not have a significant effect on the clinical outcome.

Adenovirus infections in solid organ transplant recipients

PURPOSE OF REVIEW

Adenoviruses are emerging as important viral pathogens in solid organ transplant recipients, impacting morbidity, graft survival and even mortality. This review will discuss the current understanding of the epidemiology, diagnosis and therapy of adenovirus infection in transplant recipients.

RECENT FINDINGS

Advances in the field include the use of polymerase chain reaction in the diagnosis of adenoviral infection, a better understanding of the epidemiology, immune response and potential new therapies, including preemptive and adoptive immunotherapy strategies. Adenoviral infections appear to be common, especially in pediatric solid organ transplant. Generally well tolerated, some high-risk patients may develop disseminated disease causing graft failure, which may lead to retransplant and/or death. Antiviral therapy and immunotherapy may play a role in these patients, although prospective controlled data are not available at this time.

SUMMARY

Although new tools and a better understanding of the epidemiology, risk factors and therapies for adenovirus are beginning to materialize, prospective, controlled trials, using careful definitions, and standardized methodologies need to be performed to more fully clarify these issues in solid organ transplant recipients.