Phase 1 evaluation of the respiratory syncytial virus-specific monoclonal antibody palivizumab in recipients of hematopoietic stem cell transplants

Characterization of Treatment Resistance and Viral Kinetics in the Setting of Single-Active Versus Dual-Active Monoclonal Antibodies Against Severe Acute Respiratory Syndrome Coronavirus 2

BACKGROUND

Monoclonal antibodies (mAbs) represent a crucial antiviral strategy for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but it is unclear whether combination mAbs offer a benefit over single-active mAb treatment. Amubarvimab and romlusevimab significantly reduced the risk of hospitalizations or death in the ACTIV-2/A5401 trial. Certain SARS-CoV-2 variants are intrinsically resistant against romlusevimab, leading to only single-active mAb therapy with amubarvimab in these variants. We evaluated virologic outcomes in individuals treated with single- versus dual-active mAbs.

METHODS

Participants were nonhospitalized adults at higher risk of clinical progression randomized to amubarvimab plus romlusevimab or placebo. Quantitative SARS-CoV-2 RNA levels and targeted S-gene next-generation sequencing was performed on anterior nasal samples. We compared viral load kinetics and resistance emergence between individuals treated with effective single- versus dual-active mAbs depending on the infecting variant.

RESULTS

Study participants receiving single- or dual-active mAbs had similar demographics, baseline nasal viral load, symptom score, and symptom duration. Compared with single-active mAb treatment, treatment with dual-active mAbs led to faster viral load decline at study days 3 (P < .001) and 7 (P < .01). Treatment-emergent resistance mutations were more likely to be detected after amubarvimab plus romlusevimab treatment than with placebo (2.6% vs 0%; P < .001) and were more frequently detected in the setting of single-active compared with dual-active mAb treatment (7.3% vs 1.1%; P < .01). Single-active and dual-active mAb treatment resulted in similar decrease in rates of hospitalizations or death.

CONCLUSIONS

Compared with single-active mAb therapy, dual-active mAbs led to similar clinical outcomes but significantly faster viral load decline and a lower risk of emergent resistance.

Respiratory Syncytial Virus Infection in Older Adults: An Update

Respiratory syncytial virus (RSV) infection represents one of the most common infections during childhood, with significant morbidity and mortality in newborns and in the early years of life. RSV is a common infection throughout all age groups, largely undetected and underestimated in adults, with a disproportionately high impact in older individuals. RSV infection has a wide range of clinical presentations, from asymptomatic conditions to acute pneumonia and severe life-threatening respiratory distress, including exacerbations of underlying chronic conditions. Overall, the incidence of RSV infections requiring medical attention increases with age, and it is highest among persons ≥ 70 years of age. As a consequence of a combination of an aging population, immunosenescence, and the related increased burden of comorbidities, high-income countries are at risk of developing RSV epidemics. The standard of care for RSV-infected patients remains supportive, including fluids, antipyretics, and oxygen support when needed. There is an urgent need for antivirals and preventive strategies in this population, particularly in individuals at higher risk of severe outcomes following RSV infection. In this review, we describe prevention and treatment strategies for RSV illnesses, with a deep focus on the novel data on vaccination that has become available (Arexvy, GSK, and Abrysvo, Pfizer) for older adults.

Respiratory Syncytial Virus Infections in Recipients of Bone Marrow Transplants: A Systematic Review and Meta-Analysis

Human Respiratory Syncytial Virus (RSV) is a common cause of respiratory tract infections. Usually associated with infants and children, an increasing amount of evidence suggests that RSV can cause substantial morbidity and mortality in immunocompromised individuals, including recipients of bone marrow transplantation (BMT). The present systematic review was therefore designed in accordance with the PRISMA guidelines to collect available evidence about RSV infections in BMT recipients. Three medical databases (PubMed, Embase, and MedRxiv) were therefore searched for eligible observational studies published up to 30 September 2023 and collected cases were pooled in a random-effects model. Heterogeneity was assessed using I2 statistics. Reporting bias was assessed by means of funnel plots and regression analysis. Overall, 30 studies were retrieved, including 20,067 BMT cases and 821 RSV infection episodes. Of them, 351 were lower respiratory tract infections, and a total of 78 RSV-related deaths were collected. A pooled attack rate of 5.40% (95% confidence interval [95%CI] 3.81 to 7.60) was identified, with a corresponding incidence rate of 14.77 cases per 1000 person-years (95%CI 9.43 to 20.11), and a case fatality ratio (CFR) of 7.28% (95%CI 4.94 to 10.60). Attack rates were higher in adults (8.49%, 95%CI 5.16 to 13.67) than in children (4.79%, 95%CI 3.05 to 7.45), with similar CFR (5.99%, 95%CI 2.31 to 14.63 vs. 5.85%, 95%CI 3.35 to 10.02). By assuming RSV attack rates as a reference group, influenza (RR 0.518; 95%CI 0.446 to 0.601), adenovirus (RR 0.679, 95%CI 0.553 to 0.830), and human metapneumovirus (RR 0.536, 95%CI 0.438 to 0.655) were associated with a substantially reduced risk for developing corresponding respiratory infection. Despite the heterogeneous settings and the uneven proportion of adult and pediatric cases, our study has identified high attack rates and a substantial CFR of RSV in recipients of BMT, stressing the importance of specifically tailored preventive strategies and the need for effective treatment options.

In-vivo and human evidence for potential efficacy of therapeutic polyclonal RSV neutralizing antibodies for palivizumab-resistant RSV infections

BACKGROUND

Monoclonal antibody (palivizumab), intravenous immune globulin (IGIV), or respiratory syncytial virus (RSV)-polyclonal-hyperimmune-globulin (RSV-IG as Respigam®, RI-001, RI-002) are used with ribavirin in RSV-infected immunocompromised patients, with debated efficacy. Palivizumab-resistance (PR) can arise during treatment of persistent infections in this population. RSV-IG may confer benefit in PR-RSV infection.

METHODS

RSV-IG [RI-001] was provided for an immunocompromised infant with RSV-pneumonitis refractory to ribavirin and palivizumab. RSV-neutralizing antibody, respiratory RSV load (qPCR), and F-gene-sequence-detection of PR was determined. Prophylactic RSV-IG [RI-002] or palivizumab was administered in a cotton-rat model infected with wild-type and PR-RSV. Lung RSV load and neutralizing antibody were measured.

RESULTS

As protective RI-001-neutralizing antibody titers waned in the infant, a subpopulation of PR-escape mutants were detected with a fatal RSV-burden in the lungs. In PR-RSV-infected cotton rats, prophylactic RI-002 reduced RSV-load in the lungs (2.45 vs 0.28 log10 PFU/g lung-tissue reduction, respectively, p < 0.05) and provided protective RSV-neutralizing antibody.

CONCLUSIONS

RSV-IG and ribavirin use in immunocompromised patients requires further study.

The Impact of the COVID-19 Pandemic on Respiratory Syncytial Virus Infection: A Narrative Review

Respiratory syncytial virus (RSV) is one of the most common respiratory viruses. It not only affects young children but also the elderly and immunocompromised patients. After the emergence of SARS-CoV-2 and the corona virus disease 2019 (COVID-19) era, a dramatic reduction in RSV activity was found, which coincided with the implementation of public health and social measures (PHSMs). However, the correlation is more complicated than we initially thought. After PHSMs were gradually lifted, a seasonality shift and a delayed RSV outbreak with greater number of infected patients were found in numerous countries, such as Israel, Australia, South Africa, New Zealand, France, United States, and Japan. Several hypotheses and possible reasons explaining the interaction between SARS-CoV-2 and RSV were mentioned. Since RSV vaccinations are still under investigation, administration of palivizumab should be considered in high-risk patients. In the post-COVID-19 era, greater attention should be paid to a further resurgence of RSV. In this narrative review, we conducted a thorough review of the current knowledge on the epidemiology of RSV during the COVID-19 era, the out-of-season outbreak of RSV, and the data on co-infection with RSV and SARS-CoV-2.

A monoclonal antibody targeting nonjunctional claudin-1 inhibits fibrosis in patient-derived models by modulating cell plasticity

Tissue fibrosis is a key driver of end-stage organ failure and cancer, overall accounting for up to 45% of deaths in developed countries. There is a large unmet medical need for antifibrotic therapies. Claudin-1 (CLDN1) is a member of the tight junction protein family. Although the role of CLDN1 incorporated in tight junctions is well established, the function of nonjunctional CLDN1 (njCLDN1) is largely unknown. Using highly specific monoclonal antibodies targeting a conformation-dependent epitope of exposed njCLDN1, we show in patient-derived liver three-dimensional fibrosis and human liver chimeric mouse models that CLDN1 is a mediator and target for liver fibrosis. Targeting CLDN1 reverted inflammation-induced hepatocyte profibrogenic signaling and cell fate and suppressed the myofibroblast differentiation of hepatic stellate cells. Safety studies of a fully humanized antibody in nonhuman primates did not reveal any serious adverse events even at high steady-state concentrations. Our results provide preclinical proof of concept for CLDN1-specific monoclonal antibodies for the treatment of advanced liver fibrosis and cancer prevention. Antifibrotic effects in lung and kidney fibrosis models further indicate a role of CLDN1 as a therapeutic target for tissue fibrosis across organs. In conclusion, our data pave the way for further therapeutic exploration of CLDN1-targeting therapies for fibrotic diseases in patients.

Engineered DNA-encoded monoclonal antibodies targeting Plasmodium falciparum circumsporozoite protein confer single dose protection in a murine malaria challenge model

Novel approaches for malaria prophylaxis remain important. Synthetic DNA-encoded monoclonal antibodies (DMAbs) are a promising approach to generate rapid, direct in vivo host-generated mAbs with potential benefits in production simplicity and distribution coupled with genetic engineering. Here, we explore this approach in a malaria challenge model. We engineered germline-reverted DMAbs based on human mAb clones CIS43, 317, and L9 which target a junctional epitope, major repeat, and minor repeat of the Plasmodium falciparum circumsporozoite protein (CSP) respectively. DMAb variants were encoded into a plasmid vector backbone and their expression and binding profiles were characterized. We demonstrate long-term serological expression of DMAb constructs resulting in in vivo efficacy of CIS43 GL and 317 GL in a rigorous mosquito bite mouse challenge model. Additionally, we engineered an Fc modified variant of CIS43 and L9-based DMAbs to ablate binding to C1q to test the impact of complement-dependent Fc function on challenge outcomes. Complement knockout variant DMAbs demonstrated similar protection to that of WT Fc DMAbs supporting the notion that direct binding to the parasite is sufficient for the protection observed. Further investigation of DMAbs for malaria prophylaxis appears of importance.

Monoclonal antibodies for prophylaxis and treatment of respiratory viral infections

PURPOSE OF REVIEW

Monoclonal antibody (mAb) administration represents an important strategy for preventing and treating respiratory viral infections in vulnerable populations, including immunocompromised individuals. The purpose of this review is to provide an overview of mAbs in clinical use against respiratory viruses, highlight factors that modulate mAb clinical efficacy, and provide a perspective on future innovations in the field. This review focuses on publications from the last year.

RECENT FINDINGS

Historically, clinical development of a single mAb has taken over a decade. The COVID-19 pandemic has demonstrated that this timeframe can be reduced to less than a year and has catalyzed rapid innovations in the field. Several novel mAbs against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have received emergency use authorization by the Food and Drug Administration (FDA) for the early treatment of mild to moderate COVID-19. However, the majority of these mAbs have ultimately failed due to the emergence of variants, highlighting an important lesson about predicting and countering resistance. Novel mAbs are also in clinical use or in late-stage development for the prevention of infection by SARS-CoV-2 and respiratory syncytial virus (RSV) in vulnerable populations. Several factors can be modulated to improve the clinical efficacy of mAbs. For example, Fc modifications can extend mAb half-life and increase respiratory tract bioavailability, both of which are attractive properties for achieving protection against respiratory viruses.

SUMMARY

The mAb landscape is rapidly evolving with numerous examples of success and failure. The armamentarium of clinically-available mAbs to protect vulnerable populations is expected to undergo continued growth.

Review of respiratory syncytial virus infection among older adults and transplant recipients

Respiratory syncytial virus (RSV) is a common cause of pulmonary infection among children and has been increasingly recognized as an important respiratory pathogen in older adults and immunocompromised hosts. Among older adults, RSV can lead to exacerbations of underlying lung and cardiac disease. It is also associated with significant morbidity and mortality in hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients and may be associated with acute rejection and chronic lung allograft dysfunction among lung transplant recipients (LTRs). Current treatment options for severe RSV disease are limited, and there is a paucity of guidance on RSV treatment among older adults. This narrative review provides a comprehensive overview of RSV disease in older adults, HSCT recipients, and SOT recipients. Nosocomial spread has been reported, thus highlighting the importance of infection prevention and control measures to prevent outbreaks. Antivirals, monoclonal antibodies for immunoprophylaxis, and vaccine development are underway; however, future research is still needed in these critical areas.

Monoclonal Antibody Treatment of RSV Bronchiolitis in Young Infants: A Randomized Trial

BACKGROUND

Monoclonal antibody to respiratory syncytial virus (RSV; palivizumab) is recommend for prophylaxis of high-risk infants during bronchiolitis seasons but not for RSV bronchiolitis treatment. Our aim was to determine if palivizumab would be helpful in young infants with acute RSV bronchiolitis.

METHODS

Eligible infants ≤3 months old presenting to the pediatric emergency service with RSV-positive bronchiolitis requiring inpatient admission underwent double-blind random assignment to single-dose intravenous palivizumab (15 mg/kg) or placebo. The primary efficacy outcome was the need for inpatient readmission in the 3 weeks after discharge. Secondary outcomes were time to readiness for hospital discharge, need for PICU on the initial admission, and need for revisit not requiring readmission for the same illness during 3-week follow-up.

RESULTS

A total of 420 infants (median age 49 days) diagnosed with RSV bronchiolitis were randomly assigned; 417 received treatment, and 413 completed follow-up. Readmission during follow-up was needed for 23 (11%) patients on palivizumab and 19 (9.3%) patients in the placebo group (difference 1.8%; 95% confidence interval -4.4% to 7.7%; P = .51). Geometric mean time to readiness for discharge was 29.5 hours for the palivizumab group and 30.2 hours for the placebo group (ratio 0.98; 95% confidence interval 0.81 to 1.20). No safety issues were reported.

CONCLUSIONS

Intravenous palivizumab did not appear to help or harm young infants with acute RSV-positive bronchiolitis.

Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are common among the general population; however, these often mild viral illnesses can lead to serious morbidity and mortality among recipients of hematopoietic stem cell and solid organ transplantation. The disease spectrum ranges from asymptomatic or mild infections to life-threatening lower respiratory tract infection or long-term airflow obstruction syndromes. Progression to lower respiratory tract infection or to respiratory failure is determined by the intrinsic virulence of the specific viral pathogen as well as various host factors, including the type of transplantation, status of the host’s immune dysfunction, the underlying disease, and other comorbidities. This chapter focuses on the epidemiology, clinical manifestations, diagnosis, and management of RVIs in this susceptible population and includes respiratory syncytial virus, parainfluenza virus, human metapneumovirus, influenza virus, human coronavirus, and human rhinovirus. The optimal management of these infections is limited by the overall paucity of available treatment, highlighting the need for new antiviral drug or immunotherapies.

Soluble F proteins exacerbate pulmonary histopathology after vaccination upon respiratory syncytial virus challenge but not when presented on virus-like particles

Respiratory syncytial virus (RSV) fusion (F) protein is suggested to be a protective vaccine target although its efficacy and safety concerns remain not well understood. We investigated immunogenicity, efficacy, and safety of F proteins in a soluble form or on virus-like particle (F-VLP). F VLP preferentially elicited IgG2a antibody and T helper type 1 (Th1) immune responses whereas F protein induced IgG1 isotype and Th2 responses. Despite lung viral clearance after prime or prime-boost and then RSV challenge, F protein immune mice displayed weight loss and lung histopathology and high mucus production and eosinophils. In contrast, prime or prime-boost vaccination of F VLP induced effective protection, prevented infiltration of eosinophils and vaccine- enhanced disease after challenge. This study provides insight into developing an effective and safe RSV vaccine candidate.

Clinical characteristics and treatment outcomes among respiratory syncytial virus (RSV)-infected hematologic malignancy and hematopoietic stem cell transplant recipients receiving palivizumab

Palivizumab has been used to treat respiratory syncytial virus (RSV)-infected hematologic malignancy patients at our institution based on limited published data. We conducted this retrospective study to evaluate clinical outcomes and mortality rates of RSV-infected hematologic malignancy patients from 2007 to 2016. A total of 67 patients (19 received palivizumab and 47 received supportive care) were identified. Palivizumab-treated patients had a significantly higher proportion of underlying ischemic heart disease, graft-versus-host-disease, hypogammaglobulinemia, and concomitant pulmonary infections. There were no significant differences in mortality rates or readmission rates between the two groups. The estimated odds ratio for death in patients receiving palivizumab after adjusting for propensity scores and covariates were 0.12 ([0.01, 1.32], p = .08) and 0.09 ([0.01, 1.03], p = .05) respectively. After adjustment for factors associated with severity of illness, there was no difference in mortality among patients treated with palivizumab.

Viral pneumonia: etiologies and treatment

Viral pathogens are increasingly recognized as a cause of pneumonia, in immunocompetent patients and more commonly among immunocompromised. Viral pneumonia in adults could present as community-acquired pneumonia (CAP), ranging from mild disease to severe disease requiring hospital admission and mechanical ventilation. Moreover, the role of viruses in hospital-acquired pneumonia and ventilator-associated pneumonia as causative agents or as co-pathogens and the effect of virus detection on clinical outcome are being investigated.More than 20 viruses have been linked to CAP. Clinical presentation, laboratory findings, biomarkers, and radiographic patterns are not characteristic to specific viral etiology. Currently, laboratory confirmation is most commonly done by detection of viral nucleic acid by reverse transcription-PCR of respiratory secretions.Apart from the US Food and Drug Administration-approved medications for treatment of influenza pneumonia, the treatment of non-influenza respiratory viruses is limited. Moreover, the evidence supporting the use of available antivirals to treat immunocompromised patients is modest at best. With the widespread use of molecular diagnostics, an aging population, and advancement in cancer therapy, physicians will face a bigger challenge in managing viral respiratory tract infections. Emphasis on infection control measures to prevent the spread of respiratory viruses especially in healthcare settings is extremely important.

Compassionate use experience with high-titer respiratory syncytical virus (RSV) immunoglobulin in RSV-infected immunocompromised persons

BACKGROUND

Respiratory syncytial virus (RSV) may cause fatal lower respiratory tract infection (LRTI) in immunocompromised patients. Ribavirin with or without standard intravenous immunoglobulin (IVIG) is frequently given although efficacy is debated. Infusion of IVIG with high levels of neutralizing antibody against RSV may offer benefit in these patients.

METHODS

RI-001 contains standardized levels of high-titer anti-RSV neutralizing antibody and was provided for compassionate use to 15 patients with RSV LRTI who either failed conventional therapy or had significant risk of progression. Patients were treated on day 1 with RI-001 1500 mg/kg, followed 2 days later with 750 mg/kg. Pre- and post-infusion sera were measured for RSV neutralizing antibody. Patient data were analyzed for safety related to infusion of RI-001, and clinical outcomes.

RESULTS

Patients ranged in age from 2 months to 71 years and 80% had hematologic malignancy or were bone marrow or hematopoietic stem cell transplant recipients. Administration was well tolerated. Pre-infusion neutralizing titers ranged from 51 to 1765 geometric mean titer (mean 646±519) and all patients demonstrated at least a 4-fold rise (mean 6410±4470) 5-10 days post infusion. Eleven of 15 improved and were discharged from the hospital. Days from positive RSV test to RI-001 treatment was shorter in survivors compared to non-survivors (4.4±2.8 vs. 20.3±21.0 days, P=.02).

CONCLUSION

Administration of RI-001 was well tolerated and resulted in significant increases in serum neutralizing antibody titers to RSV. Our data suggest that early identification of RSV and treatment with RI-001 may offer benefit.

Human rhinovirus detection in the lower respiratory tract of hematopoietic cell transplant recipients: association with mortality

Human rhinoviruses are the most common respiratory viruses detected in patients after hematopoietic cell transplantation. Although rhinovirus appears to occasionally cause severe lower respiratory tract infection in immunocompromised patients, the clinical significance of rhinovirus detection in the lower respiratory tract remains unknown. We evaluated 697 recipients transplanted between 1993 and 2015 with rhinovirus in respiratory samples. As comparative cohorts, 273 recipients with lower respiratory tract infection caused by respiratory syncytial virus (N=117), parainfluenza virus (N=120), or influenza (N=36) were analyzed. Factors associated with mortality were analyzed using Cox proportional hazard models. Among 569 subjects with rhinovirus upper respiratory tract infection and 128 subjects with rhinovirus lower respiratory tract infection, probabilities of overall mortality at 90 days were 6% and 41%, respectively (P<0.001). The survival rate after lower respiratory tract infection was not affected by the presence of co-pathogens (55% in patients with co-pathogens, 64% in patients without, P=0.34). Low monocyte count (P=0.027), oxygen use (P=0.015), and steroid dose greater than 1 mg/kg/day (P=0.003) before diagnosis were significantly associated with mortality among patients with lower respiratory tract infection in multivariable analysis. Mortality after rhinovirus lower respiratory tract infection was similar to that after lower respiratory tract infection by respiratory syncytial virus, parainfluenza virus or influenza in an adjusted model. In summary, transplant recipients with rhinovirus detection in the lower respiratory tract had high mortality rates comparable to viral pneumonia associated with other well-established respiratory viruses. Our data suggest rhinovirus can contribute to severe pulmonary disease in immunocompromised hosts.

Viral Pneumonia in Patients with Hematologic Malignancy or Hematopoietic Stem Cell Transplantation

Viral pneumonias in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation cause significant morbidity and mortality. Advances in diagnostic techniques have enabled rapid identification of respiratory viral pathogens from upper and lower respiratory tract samples. Lymphopenia, myeloablative and T-cell depleting chemotherapy, graft-versus-host disease, and other factors increase the risk of developing life-threatening viral pneumonia. Chest imaging is often nonspecific but may aid in diagnoses. Bronchoscopy with bronchoalveolar lavage is recommended in those at high risk for viral pneumonia who have new infiltrates on chest imaging.

Consensus conference on the appropriateness of palivizumab prophylaxis in respiratory syncytial virus disease

Respiratory syncytial virus infection represents a clinical burden among young children under 24 months. Palivizumab is the only drug licensed in Italy for the prevention of serious lower respiratory tract disease requiring hospitalization caused by respiratory syncytial virus in children at high risk. However recommendations for palivizumab prophylaxis are heterogeneous. Not all the published documents agree about the clinical indications of palivizumab; this could lead to different clinical practices and concerns about the appropriateness of prophylaxis. These issues and the lack of evidence about palivizumab prophylaxis efficacy in specific medical conditions brought on the idea of a consensus conference on the current recommendations for the management and prevention of bronchiolitis, in order to share useful indications. The goal was to perform a review of the evidence regarding the efficacy and the safety of palivizumab and give recommendations in order to harmonize its use. A structured and validated method to conduct the consensus process was adopted. The consensus conference recommends palivizumab prophylaxis in infants born before 29 weeks and younger than 12 months at the start of the epidemic season. According to evidence from literature and experts' opinion, palivizumab prophylaxis is not recommended in preterm infants of gestational age ≥29 weeks, without co-morbidity (i.e., cardiac, bronchopulmonary diseases). The experts identified some clinical rare conditions for which the decision of prophylaxis should be entrusted to the specialists. The evaluation of the appropriateness of palivizumab prophylaxis in the single patient should be documented by the specialists. Pediatr Pulmonol. 2016;51:1088-1096. © 2016 Wiley Periodicals, Inc.

BCSH/BSBMT/UK clinical virology network guideline: diagnosis and management of common respiratory viral infections in patients undergoing treatment for haematological malignancies or stem cell transplantation

A joint working group established by the Haemato-oncology subgroup of the British Committee for Standards in Haematology, the British Society for Bone Marrow Transplantation and the UK Clinical Virology Network has reviewed the available literature and made recommendations for the diagnosis and management of respiratory viral infections in patients with haematological malignancies or those undergoing haematopoietic stem cell transplantation. This guideline includes recommendations for the diagnosis, prevention and treatment of respiratory viral infections in adults and children. The suggestions and recommendations are primarily intended for physicians practising in the United Kingdom.

Corticosteroid use as adjunct therapy for respiratory syncytial virus infection in adult allogeneic stem cell transplant recipients

BACKGROUND

Respiratory syncytial virus (RSV) infection causes significant morbidity and mortality in allogeneic stem cell transplant (allo-SCT) recipients. Although ribavirin and immunoglobulins are common components of therapy, the role of adjunct corticosteroids is not established.

OBJECTIVES

We sought to evaluate corticosteroid utilization in the setting of post-allo-SCT RSV infection in our center and assess post-transplant outcomes including pulmonary function decline.

METHODS

Patients with a history of RSV infection from 2008 to 2014 seen at our institution were identified. Treatment and outcome data were retrospectively collected. Forced expiratory volume at 1 s (FEV1) and carbon monoxide diffusion capacity (DLCO) were collected pre- and post-RSV infection.

RESULTS

During the observation period, RSV was isolated in 53 of 552 patients undergoing allo-SCT (10%) and 45 had evaluable therapy data. RSV-related mortality in this cohort was 4/45 (9%). Twenty-one (47%) were on corticosteroids prior to RSV diagnosis, of whom 11 (24%) had a dose increase post symptom onset. Eight (18%) patients were started on corticosteroids at the time of RSV infection. Corticosteroid therapy at symptom onset was associated with a higher rate of upper respiratory infection (URTI) to lower respiratory infection (LRTI) progression risk ratio (RR) 2.49 (1.21-5.13; P = 0.016), hospital admission RR 2.05 (1.24-3.37; P = 0.005), or intensive care unit admission RR 2.91 (1.89-5.01; P = 0.002). No significant difference was seen with FEV1 and DLCO decline (P = 0.3 and 0.24, respectively) or mortality (P = 0.26).

CONCLUSION

Adjunct corticosteroid use in the setting of RSV infection did not improve RSV-related outcomes including long-term pulmonary function. Our results do not support the routine use of corticosteroids; however, this finding does need to be verified in a larger cohort of patients.

Treatment with novel RSV Ig RI-002 controls viral replication and reduces pulmonary damage in immunocompromised Sigmodon hispidus

Respiratory syncytial virus (RSV) is a significant cause of bronchiolitis and pneumonia in several high health risk populations, including infants, elderly and immunocompromised individuals. Mortality in hematopoietic stem cell transplant recipients with lower respiratory tract RSV infection can exceed 80%. It has been shown that RSV replication in immunosuppressed individuals is significantly prolonged, but the contribution of pulmonary damage, if any, to the pathogenesis of RSV disease in this susceptible population is not known. In this work, we tested RI-002, a novel standardized Ig formulation containing a high level of RSV-neutralizing Ab, for its ability to control RSV infection in immunocompromised cotton rats Sigmodon hispidus. Animals immunosuppressed by repeat cyclophosphamide injections were infected with RSV and treated with RI-002. Prolonged RSV replication, characteristic of immunosuppressed cotton rats, was inhibited by RI-002 administration. Ab treatment reduced detection of systemic dissemination of viral RNA. Importantly, pulmonary interstitial inflammation and epithelial hyperplasia that were significantly elevated in immunosuppressed animals were reduced by RI-002 administration. These results indicate the potential of RI-002 to improve outcome of RSV infection in immunocompromised subjects not only by controlling viral replication, but also by reducing damage to lung parenchyma and epithelial airway lining, but further studies are needed.

Respiratory Syncytial Virus and Human Metapneumovirus Infection in Transplant Recipients

Respiratory viral infections due to respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) cause infections in immunocompromised transplant patients ranging from mild upper respiratory infections to severe lower respiratory tract disease with respiratory failure. These viruses are more readily diagnosed due to improvements in sensitive molecular diagnostic methods. The epidemiology of RSV and hMPV is similarly becoming more readily appreciated in hematopoietic stem cell transplant (HSCT) patients of all ages as well as solid organ transplant (SOT) patients, with lung transplant recipients having evidence of more frequent and severe complications related to these viruses. RSV and hMPV infection typically but not always present with upper respiratory signs and symptoms that progress to lower respiratory tract disease. Treatment options for RSV are limited, with aerosolized, intravenous, and oral ribavirin all studied in HSCT and lung transplant patients. No antiviral therapy for the treatment of hMPV is available, although ribavirin has shown some effectiveness in vitro. New antiviral agents including RSV fusion inhibitors and nucleoside analogs are being developed, with some under clinical evaluation.

Pharmacokinetics and pharmacokinetic-pharmacodynamic relationships of monoclonal antibodies in children

Monoclonal antibodies (mAbs) constitute a therapeutically and economically important drug class with increasing use in both adult and paediatric patients. The rather complex pharmacokinetic and pharmacodynamic properties of mAbs have been extensively reviewed in adults. In children, however, limited information is currently available. This paper aims to comprehensively review published pharmacokinetic and pharmacokinetic-pharmacodynamic studies of mAbs in children. The current status of mAbs in the USA and in Europe is outlined, including a critical discussion of the dosing strategies of approved mAbs. The pharmacokinetic properties of mAbs in children are exhaustively summarised along with comparisons to reports in adults: for each pharmacokinetic process, we discuss the general principles and mechanisms of the pharmacokinetic/pharmacodynamic characteristics of mAbs, as well as key growth and maturational processes in children that might impact these characteristics. Throughout this review, considerable knowledge gaps are identified, especially regarding children-specific properties that influence pharmacokinetics, pharmacodynamics and immunogenicity. Furthermore, the large heterogeneity in the presentation of pharmacokinetic/pharmacodynamic data limited clinical inferences in many aspects of paediatric mAb therapy. Overall, further studies are needed to fully understand the impact of body size and maturational changes on drug exposure and response. To maximise future knowledge gain, we propose a 'Guideline for Best Practice' on how to report pharmacokinetic and pharmacokinetic-pharmacodynamic results from mAb studies in children which also facilitates comparisons. Finally, we advocate the use of more sophisticated modelling strategies (population analysis, physiology-based approaches) to appropriately characterise pharmacokinetic-pharmacodynamic relationships of mAbs and, thus, allow for a more rational use of mAb in the paediatric population.

Challenges and opportunities in developing respiratory syncytial virus therapeutics

Two meetings, one sponsored by the Wellcome Trust in 2012 and the other by the Global Virology Foundation in 2013, assembled academic, public health and pharmaceutical industry experts to assess the challenges and opportunities for developing antivirals for the treatment of respiratory syncytial virus (RSV) infections. The practicalities of clinical trials and establishing reliable outcome measures in different target groups were discussed in the context of the regulatory pathways that could accelerate the translation of promising compounds into licensed agents. RSV drug development is hampered by the perceptions of a relatively small and fragmented market that may discourage major pharmaceutical company investment. Conversely, the public health need is far too large for RSV to be designated an orphan or neglected disease. Recent advances in understanding RSV epidemiology, improved point-of-care diagnostics, and identification of candidate antiviral drugs argue that the major obstacles to drug development can and will be overcome. Further progress will depend on studies of disease pathogenesis and knowledge provided from controlled clinical trials of these new therapeutic agents. The use of combinations of inhibitors that have different mechanisms of action may be necessary to increase antiviral potency and reduce the risk of resistance emergence.

Palivizumab use in Japanese infants and children with immunocompromised conditions

A total of 27/28 (96%) immunocompromised Japanese children received ≥ 4 doses of palivizumab. No respiratory syncytial virus-associated hospitalizations occurred. Mean palivizumab trough concentrations were 59.0 and 91.8 μg/mL 30 days after the 1st and 4th doses, respectively. Of 28 subjects, 27 (96%) experienced ≥ 1 adverse event and 7 (25%) experienced ≥ 1 serious adverse event, none of which was considered related to palivizumab.

Use of palivizumab in infants and young children with severe respiratory disease: a Delphi study

OBJECTIVE

To achieve a consensus of opinion among an expert group of pediatric pulmonologists regarding the appropriateness of the off-label use of palivizumab for some pediatric patients with severe respiratory diseases.

METHODS

A two-round modified Delphi technique was used. A 43-item self-administered questionnaire grouped into seven clinical scenarios was developed. Level of agreement for each statement was ranked on a 0-9 scale with 0 being total disagreement and 9 total agreement. Consensus was sought through the feedback of information and iteration. The final responses were evaluated for median and interquartile range to determine which questions the group had reached consensus about, either affirmatively or negatively.

RESULTS

Consensus was obtained for 24/43 statements (55.81%), including use of palivizumab for prevention of respiratory syncytial virus (RSV) infection in children with severe respiratory involvement due to neuromuscular disease, congenital or acquired immunodeficiency, storage disease, cystic fibrosis, diseases involving impaired ciliary clearance, patients operated on esophageal atresia and/or tracheoesophageal fistula, diaphragmatic hernia, bronchopulmonary malformations, severe tracheomalacia, lung transplant recipients and patients in the waiting list for lung transplant, patients oxygen-dependent for severe interstitial pulmonary disease and patients with severe pulmonary hypertension. Consensus against the use of palivizumab as prevention of RSV infection was also achieved in almost all the recurrent wheezing/asthma attacks situations.

CONCLUSION

A set of indication for off-label uses of palivizumab in pediatric pulmonology was developed in accordance with the degree of professional consensus on which they were based. The applicability of the present results to clinical practice should be evaluated individually and reviewed periodically in the light of new emerging evidence. Further studies are needed to add evidence to the most frequent and clinically oriented scenarios that have shown higher levels of uncertainty.

Respiratory syncytial virus in hematopoietic cell transplant recipients: factors determining progression to lower respiratory tract disease

BACKGROUND

Respiratory syncytial virus (RSV) lower respiratory tract disease (LRD) is a life-threatening complication in hematopoietic cell transplant (HCT) recipients. Lymphopenia has been associated with an increased risk of progression from upper respiratory tract infection (URI) to LRD.

METHODS

This study retrospectively analyzed the significance of lymphocyte engraftment dynamics, lung function, smoking history, corticosteroids, antiviral treatment, viral subtypes, and RSV-specific neutralizing antibodies for the progression to LRD in 181 HCT recipients with RSV URI.

RESULTS

In multivariable models, smoking history, conditioning with high-dose total body irradiation, and an absolute lymphocyte count (ALC) ≤100/mm(3) at the time of URI onset were significantly associated with disease progression. No progression occurred in patients with ALCs of >1000/mm(3) at URI onset. Lymphocyte engraftment dynamics were similar in progressors and nonprogressors. Pre- and posttransplant donor and posttransplant recipient RSV subtype-specific neutralizing antibody levels, RSV viral subtypes, and corticosteroids also were not significantly associated with LRD progression.

CONCLUSIONS

Host and transplant related factors appear to determine the risk of progression to LRD more than viral factors. Dysfunctional cell-mediated immunity appears to be important in the pathogenesis of progressive RSV disease after HCT. A characterization of RSV-specific T-cell immunity is warranted.

Diagnosis and treatment of viral diseases in recipients of allogeneic hematopoietic stem cell transplantation

Viral infections are important causes of morbidity and mortality after allogeneic stem cell hematopoietic transplantation (allo-HSCT). Although most viral infections present with asymptomatic or subclinical manifestations, viruses may result in fatal complications in severe immunocompromised recipients. Reactivation of latent viruses, such as herpesviruses, is frequent during the immunosuppression that occurs with allo-HSCT. Viruses acquired from community, such as the respiratory and gastrointestinal viruses, are also important pathogens of post-transplant viral diseases. Currently, molecular diagnostic methods have replaced or supplemented traditional methods, such as viral culture and antigen detection, in diagnosis of viral infections. The utilization of polymerase chain reaction facilitates the early diagnosis. In view of lacking efficacious agents for treatment of viral diseases, prevention of viral infections is extremely valuable. Application of prophylactic strategies including preemptive therapy reduces viral infections and diseases. Adoptive cellular therapy for restoring virus-specific immunity is a promising method in the treatment of viral diseases.

Novel antiviral agents for respiratory viral infection in immunocompromised adults

Respiratory viruses cause significant morbidity and mortality in immunocompromised populations such as stem cell transplant and solid organ transplant patients. Few viruses causing respiratory tract infection have an approved therapy, and many of the viruses have no therapeutic options at all. In this article, we describe novel agents under development for treatment options against several respiratory viruses.

Anti-viral agents: potential utility in exacerbations of asthma

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Respiratory virus infections are the single greatest precipitants of asthma exacerbations.

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Current treatment options for AE are limited and have developed little in recent years.

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Development of effective anti-viral treatments remains a key target for therapeutic intervention.

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Approaches include therapies that either target the virus or boost host response to the virus.

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New clinical studies are needed to further our understanding of the mechanisms of virus induced asthma exacerbation.

Asthma is the most common chronic respiratory disease and its prevalence is on the increase. Respiratory viral infections in early life have been suggested to increase the risk of development of asthma in later life and virus infection remains the single greatest precipitant of asthma exacerbations. The development of effective anti-viral treatments remains a key target for therapeutic intervention. Here we discuss the role of respiratory viral infection in asthma exacerbation and highlight current and potential anti-viral agents and their mechanisms of action.

Impact of aerosolized ribavirin on mortality in 280 allogeneic haematopoietic stem cell transplant recipients with respiratory syncytial virus infections

OBJECTIVES

Respiratory syncytial virus (RSV) infections are well recognized as a significant cause of morbidity and mortality in allogeneic haematopoietic stem cell transplant (allo-HSCT) recipients. We evaluated the spectrum of clinical manifestations, management (including ribavirin-based antiviral therapy) and outcomes of RSV infections and determined the risk factors associated with RSV lower respiratory tract infection (LRTI) and all-cause mortality.

METHODS

In this retrospective study, we analysed clinical data from all laboratory-confirmed RSV infections in allo-HSCT recipients (n = 280) who presented at our institution from January 1996 to May 2009.

RESULTS

Of the 280 patients, 80 (29%) developed LRTI within 20 days (median 1 day, range 0-19 days) and 44 (16%) died within 90 days (median 26 days, range 1-82 days) from RSV diagnosis. Multivariable logistic regression analyses identified several significant risk factors associated with RSV LRTI and all-cause mortality, including age, male sex, neutropenia, lymphocytopenia and lack of ribavirin-based antiviral therapy at the upper respiratory tract infection (URTI) stage. Aerosolized ribavirin-based therapy at the URTI stage was the single most significant factor in reducing the risk of RSV LRTI (83%), all-cause mortality (57%) and RSV-associated mortality (87%) in these patients (P < 0.05), irrespective of the year of RSV diagnosis.

CONCLUSIONS

Our results demonstrate that RSV infections are a significant cause of morbidity and mortality in high-risk allo-HSCT recipients and ribavirin-based antiviral therapy at the URTI stage had a positive impact on both outcomes in this vulnerable population with multiple risk factors.

Detection, control, and management of a respiratory syncytial virus outbreak in a pediatric hematology-oncology department

BACKGROUND

Immunocompromised patients are at increased risk for severe respiratory syncytial virus (RSV) infection. Palivizumab is approved for prevention of RSV in specific populations but not for treatment. Few studies demonstrated the safety and successful treatment with intravenous (IV) palivizumab. We describe our experience with IV palivizumab treatment for RSV in a pediatric hematology-oncology department during an outbreak.

METHODS

During a short period of renovations, oncology patients were placed in a general pediatric ward. After a case of severe fatal RSV pneumonia in a 2-year-old male patient with acute myeloid leukemia, all patients were actively screened twice weekly regardless of symptoms. Respiratory samples were tested for RSV using rapid immunochromatography detection, immunofluorescence, or reverse transcriptase polymerase chain reaction. A single dose of palivizumab (15 mg/kg) was given to children below 3 years of age who tested positive for RSV.

RESULTS

Over a 6-week period, 12 patients tested positive for RSV. Seven patients were treated with palivizumab. Five patients had respiratory symptoms, and 2 were asymptomatic. No adverse events were attributed to IV palivizumab treatment. Early-treated patients had no complications attributed to RSV.

CONCLUSIONS

Containment of RSV outbreak in high-risk children is difficult. Screening with reverse transcriptase polymerase chain reaction and the early use of IV palivizumab is safe and may prevent complications of RSV infection among these patients.

Outcome of respiratory syncytial virus lower respiratory tract disease in hematopoietic cell transplant recipients receiving aerosolized ribavirin: significance of stem cell source and oxygen requirement

Respiratory syncytial virus (RSV) infection is an important complication after hematopoietic cell transplantation (HCT), and RSV lower respiratory tract disease (LRD) results in substantial early mortality and late airflow obstruction among survivors. Factors associated with poor outcome are unknown. We evaluated the effect of transplant and treatment factors on overall survival, mortality from respiratory failure, and pulmonary function among 82 HCT recipients who had RSV LRD between 1990 and 2011. All patients received aerosolized ribavirin. In multivariable analyses, only the use of marrow or cord blood as graft source (adjusted hazard ratio [aHR], 4.1; 95% confidence interval [CI], 1.8 to 9.0; P < .001) and oxygen requirement (aHR, 3.3; 95% CI, 1.5 to 6.7; P = .003) remained independently associated with overall mortality and death due to respiratory failure (aHR, 4.7; 95% CI, 1.8 to 13; P = .002 and aHR, 5.4; 95% CI, 1.8 to 16; P = .002, respectively). Antibody-based treatments, including intravenous immunoglobulin and palivizumab, were not independently associated with improved outcome and did not alter the associations of the graft source and oxygen requirements in statistical models. In conclusion, use of peripheral blood stem cells as graft source and lack of oxygen requirement at diagnosis appear to be important factors associated with improved survival of HCT recipients with RSV LRD. These results may explain differences in outcomes reported from RSV infection over time and may guide the design of future interventional trials.

Respiratory syncytial virus disease: prevention and treatment

Respiratory syncytial virus (RSV) is one of the most clinically important viruses infecting young children, the elderly, and the immunocompromised. Over the past decade, the most significant advance in the prevention of RSV disease has been the development of high-titered antibody products. Infection control is the only other strategy to prevent RSV disease. A humanized monoclonal antibody directed against the fusion (F) protein palivizumab, (Synagis®, MedImmune, Inc., Gaithersburg, MD), is given routinely on a monthly basis to premature infants and young children less than 24 months of age with underlying medical problems including prematurity, chronic lung disease, or cardiac disease to prevent RSV disease and hospitalization. Other products utilizing polyclonal or monoclonal antibodies or antibody fragments against the F protein have been developed and some already tested in patient populations. The only licensed antiviral treatment available today is ribavirin, a guanosine analogue generally administered as a small particle aerosol to immunocompromised patients with lower respiratory tract disease due to RSV. This drug has also been utilized in oral and intravenous forms, again mainly in immunocompromised patients. Promising new antiviral agents under development by multiple pharmaceutical and biotechnology companies include small molecule fusion inhibitors, attachment inhibitors, inhibitors of RNA synthesis, and small interfering RNA particles (siRNA).

Respiratory syncytial virus: diagnosis, treatment and prevention

Respiratory Syncytial Virus (RSV) is a common virus that infects children and adults; however, children younger than two years of age tend to develop more serious respiratory symptoms. RSV is responsible for thousands of outpatient visits (e.g., emergency room/primary care physician), hospitalizations and can result in death. Treatment is primarily supportive care and the illness resolves without complications in most children. RSV prophylaxis with palivizumab is an option for high-risk infants and children, which can decrease hospitalization and length of stay. Immunocompromised patients are a special population of which ribavirin and palivizumab may be used for treatment. Currently, no medication or vaccine available has been able to show a reduction in mortality from RSV. Future vaccines are in the developmental stage and will hopefully decrease the symptomatic and economic burden of this disease.

Respiratory Syncytial Virus Prophylaxis in Special Populations: Is it Something Worth Considering in Cystic Fibrosis and Immunosuppression?

Respiratory syncytial virus (RSV) bronchiolitis is the leading cause of infant hospitalization in the United States. Prophylaxis with palivizumab is effective in reducing RSV hospitalizations in premature infants and in infants or children with chronic lung disease or congenital heart disease. Patients with CF or those who are immunocompromised may be at increased risk for RSV infection-related complications; hence, prophylaxis may prove beneficial to these populations. The extent of palivizumab use in the CF and immunocompromised populations is variable. Palivizumab appears to be safe and may be effective in infants and young children with CF and immunocompromise. However, well-designed, randomized, controlled trials published in peer-reviewed journals are lacking, and its routine use can therefore not be recommended at this time. If used in patients with CF or those who are immunocompromised, RSV prophylaxis should be restricted to peak outbreak months in order to optimize the cost benefit of palivizumab.

Prevalence and clinical course of viral upper respiratory tract infections in immunocompromised pediatric patients with malignancies or after hematopoietic stem cell transplantation

BACKGROUND

Respiratory tract infections (RTI) in immunosuppressed pediatric patients with malignancies or after hematopoietic stem cell transplantation (HSCT) are associated with significant morbidity and mortality. Prospective data on the incidence and clinical role of infections by respiratory viruses in this population have been lacking.

METHODS

In this prospective study, 191 children between 0 and 18 years of age were investigated by real-time polymerase chain reaction for the presence of 8 common respiratory virus types in transnasal aspirations. The study included 110 children with leukemia, lymphoma, or solid tumors (subgroup 1); 31 children after HSCT (subgroup 2); and 50 immunocompetent control patients.

RESULTS

In comparison with the control group, immunocompromised children showed a significantly higher incidence of positive virus tests (subgroup 1: 53%; subgroup 2: 81%; controls: 24%; P<0.0001), and more frequently experienced ensuing viral infections in the lower respiratory tract (subgroup 1: 74%; subgroup 2: 88%; controls: 25%; P<0.0001). Sixteen percent of these children had coinfections by 2 or more viruses and revealed more severe respiratory illness.

CONCLUSIONS

The present epidemiologic study on viral upper RTI in immunocompromised children revealed a high virus-associated morbidity which was particularly prominent in HSCT recipients. In these children, detection of viral coinfections was identified as a risk factor for a severe course of lower RTI.

Respiratory hospitalizations and respiratory syncytial virus prophylaxis in special populations

Palivizumab utilization, compliance, and outcomes were examined in infants with preexisting medical diseases within the Canadian Registry Database (CARESS) to aid in developing guidelines for potential "at-risk" infants in the future. Infants who received ≥1 dose of palivizumab during the 2006-2010 respiratory syncytial virus (RSV) seasons at 29 sites were recruited and utilization, compliance, and outcomes related to respiratory infection/illness (RI) events were collected monthly. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for premature infants ≤35 completed weeks gestational age (GA) who met standard approval criteria (group 1) compared to those with medical disorders (group 2) using Cox proportional hazards regression models with adjustment for potential confounding factors. Of 7,339 registry infants, 4,880 were in group 1 and 952 in group 2, which included those with Down syndrome (20.3%), upper airway anomalies (18.7%), pulmonary diseases (13.3%), and cystic fibrosis (12.3%). Group 2 were older at enrollment (10.2 ± 9.2 vs. 3.5 ± 3.1 months, p < 0.0005), had higher GA (35.9 ± 6.0 vs. 31.0 ± 5.4 weeks, p < 0.0005), and were less compliant with treatment intervals (69.4% vs. 72.6%, p = 0.048). A greater proportion of group 2 infants were hospitalized for RI (9.0% vs. 4.2%, p < 0.0005) and RSV (2.4% vs. 1.3%, p = 0.003) (unadjusted). Being in group 2 was associated with an increased risk of RI (HR = 2.0, 95%CI 1.5-2.5, p < 0.0005), but not RSV hospitalization (HR = 1.6, 95% CI 0.9-2.8, p = 0.106). In infants receiving palivizumab, those with underlying medical disorders, though not currently approved for prophylaxis, are at higher risk for RI events compared with preterm infants. However, risk of RSV hospitalizations is similar.

High risk for RSV bronchiolitis in late preterms and selected infants affected by rare disorders: a dilemma of specific prevention

Respiratory syncytial virus (RSV) is the most frequent aetiologic agent that causes bronchiolitis and lower respiratory tract infection in infants. These infections may be severe and even life-threatening in selected high-risk populations. Traditional, well-established, high-risk populations are preterm infants with or without chronic lung disease and children with congenital heart disease. For these children, RSV prophylaxis using palivizumab, a monoclonal anti-RSV humanised antibody against the F-protein of RSV, has proven safe and efficacious in preventing RSV-related hospitalisation. Recently, a number of rare medical conditions have been associated with the risk of severe RSV infections. Evidence of safety and efficacy of RSV prophylaxis in these populations is lacking. Given the low incidence of these conditions, randomised trials are not feasible. A practical, opinion-based approach to this dilemma is offered in this paper. It is proposed that these rare disorders may qualify for RSV prophylaxis if the association between a specific condition and the risk of severe RSV infection is confirmed in at least 3 independent publications, of which at least 1 includes a prospective cohort study. To facilitate pharmaco-economic analyses, at least one of the three studies must also report on the absolute risk of severe RSV infection in the specified illness. The authors believe that qualification criteria will enable caregivers to target RSV prophylaxis more effectively in children with rare conditions and the proposed approach provides direction for future epidemiological studies on the risk of severe RSV infection in children with these uncommon, medical illnesses.

The epidemiology and clinical characteristics of respiratory syncytial virus infection in children at a public pediatric referral hospital in Mexico

OBJECTIVES

The aim of this study was to determine the epidemiological and clinical characteristics of children with respiratory syncytial virus (RSV) treated at a public referral children's hospital in Mexico.

METHODS

We reviewed RSV infection in patients aged 0-18 years who were treated at Hospital Infantil from January 2004 to December 2008.

RESULTS

During the 5 years, 2797 samples were tested for respiratory viruses; 356 samples were positive for any virus, including 266 (74.7%) positive for RSV. Complete clinical information was available for 205 RSV patients. The mean age was 22 months, and 33.7% of the infections were nosocomially acquired. Hospitalization occurred in 187 children. Of 14 deaths, nine were directly attributed to RSV infection. During the study, RSV infections were seen throughout the year, predominating in the colder months. Of the 205 patients, 79.0% (162/205) had an underlying disease. Congenital heart disease was found in 30.2% (49/162), including three children (33.3%) who died of RSV. Thirty-three patients (16.1%) with RSV required mechanical ventilation. None of the children with RSV received palivizumab or ribavirin.

CONCLUSIONS

RSV caused high hospitalization rates and admission to intensive care units, especially among those with underlying illnesses and young infants. The data presented here will be useful for strategies to improve outcomes in children at risk of complications.

Prophylaxis and treatment of respiratory syncytial virus in adult immunocompromised patients

OBJECTIVE

To review the literature regarding current strategies and strategies under active development for the prevention and treatment of respiratory syncytial virus (RSV) infections in immunocompromised adults.

DATA SOURCES

The MEDLINE/PubMed, EMBASE, and Cochrane databases were queried from January 1980 to December 2011 for articles in English using these associated search terms: respiratory syncytial virus, ribavirin, intravenous immunoglobulin, IVIG, palivizumab, motavizumab, lung, pneumonia, transplantation, bone marrow, cancer, malignancy, and vaccine.

STUDY SELECTION AND DATA EXTRACTION

All relevant original studies, meta-analyses, systematic reviews, and review articles were assessed for inclusion. References from pertinent articles were examined for additional content not found during the initial search.

DATA SYNTHESIS

RSV in the immunocompromised adult can lead to significant morbidity and mortality. Treatment of RSV-infected adults is limited to antiviral therapy with ribavirin (aerosolized, oral, intravenous) and immunomodulation with intravenous immunoglobulins, corticosteroids, and palivizumab. Existing literature is predominantly case reports, small trials, and retrospective reviews of patients infected with RSV who have undergone lung or hematopoietic stem cell transplantation (HSCT). Palivizumab may be a viable option for prophylaxis against RSV in high-risk adults. Ribavirin is the most studied treatment option and should remain the backbone of multidrug regimens. Of the routes of administration, aerosolized ribavirin carries the preponderance of evidence and, though challenging, is preferred to limit systemic toxicities in the infected patient. Addition of an immunomodulator to ribavirin may provide a survival benefit over ribavirin alone; however, this has only been studied in a subset of HSCT patients with lower respiratory tract RSV infection.

CONCLUSIONS

Research most strongly supports the use of aerosolized ribavirin as the treatment strategy for immunocompromised adults with RSV. Addition of an immunomodulator may provide a survival benefit over ribavirin alone. Strategies and supportive data for the prevention of RSV infection in the high-risk adult are critically needed.

Risk factors for severe respiratory syncytial virus lower respiratory tract infection

RSV infection is a leading cause of lower respiratory tract infection, especially in High-risk infants with a history of prematurity, bronchopulmonary dysplasia (BPD), congenital heart disease (CHD), neuromusculair impairment, immunodeficiency, and Down syndrome. Host related risk factors that have been identified to be associated with severe RSV related lower respiratory tract infection include young age below 6 months at the beginning of RSV season, multiple birth, male sex, low socioeconomic status and parental education, crowded living conditions, young siblings, maternal smoking and indoor smoke pollution, malnutrition/small for gestational age, family history of atopy or asthma, low cord serum RSV antibody titers, and living at altitude.Risk factors increasing the risk of acquisition of RSV have been identified to be birth before and/or during RSV season, day care attendance, presence of older siblings in school or day-care, and lack of breast feeding. Some of these risk factors are discussed controversially and some of them are found continuously throughout the literature.Given the high cost of RSV prophylaxis, especially for the large population of late preterm infants, algorithms and risk score systems have been published that could identify high-risk infants for treatment with palivizumab out of this gestational age group. Several models reported on an average sensitivity and specificity of 70 percent and, thus, are helpful to identify infants at high risk for severe RSV infection and need for prophylaxis with palivizumab.

Progress in understanding and controlling respiratory syncytial virus: still crazy after all these years

Human respiratory syncytial virus (RSV) is a ubiquitous pathogen that infects everyone worldwide early in life and is a leading cause of severe lower respiratory tract disease in the pediatric population as well as in the elderly and in profoundly immunosuppressed individuals. RSV is an enveloped, nonsegmented negative-sense RNA virus that is classified in Family Paramyxoviridae and is one of its more complex members. Although the replicative cycle of RSV follows the general pattern of the Paramyxoviridae, it encodes additional proteins. Two of these (NS1 and NS2) inhibit the host type I and type III interferon (IFN) responses, among other functions, and another gene encodes two novel RNA synthesis factors (M2-1 and M2-2). The attachment (G) glycoprotein also exhibits unusual features, such as high sequence variability, extensive glycosylation, cytokine mimicry, and a shed form that helps the virus evade neutralizing antibodies. RSV is notable for being able to efficiently infect early in life, with the peak of hospitalization at 2-3 months of age. It also is notable for the ability to reinfect symptomatically throughout life without need for significant antigenic change, although immunity from prior infection reduces disease. It is widely thought that re-infection is due to an ability of RSV to inhibit or subvert the host immune response. Mechanisms of viral pathogenesis remain controversial. RSV is notable for a historic, tragic pediatric vaccine failure involving a formalin-inactivated virus preparation that was evaluated in the 1960s and that was poorly protective and paradoxically primed for enhanced RSV disease. RSV also is notable for the development of a successful strategy for passive immunoprophylaxis of high-risk infants using RSV-neutralizing antibodies. Vaccines and new antiviral drugs are in pre-clinical and clinical development, but controlling RSV remains a formidable challenge.

A review of palivizumab and emerging therapies for respiratory syncytial virus

INTRODUCTION

Respiratory syncytial virus (RSV) is an important pathogen in children and adults; however, current treatment options are primarily supportive. Palivizumab, the only approved specific monoclonal antibody for RSV is used prophylactically to reduce morbidity in a select population of high-risk children.

AREAS COVERED

The development and current use of palivizumab; the potential role of palivizumab as preventive therapy in patients with cystic fibrosis, asthma and compromised immune systems; and explores the limited research in which palivizumab has been used for treatment of RSV. The modified recommendations for the use of palivizumab espoused by the American Academy of Pediatrics and research on the cost-effectiveness of this product are presented. In addition, the authors discuss the development of enhanced monoclonal antibodies including motavizumab, which was recently denied FDA approval for preventative therapy. The authors explore the historical and current efforts to develop a vaccine targeting RSV. The current status of antiviral drug development is also reviewed. The literature search included RSV-Ig, palivizumab, and emerging drugs and vaccines for the treatment of RSV as keywords and titles from 1997 to 2011.

EXPERT OPINION

Although there are potential drugs and vaccines in development to prevent or reduce the effects of RSV infection, palivizumab remains the only licensed product to reduce the severity of disease in high-risk pediatric patients.

Respiratory viral infections in hematopoietic stem cell and solid organ transplant recipients

Respiratory viral infections (RVIs) are common causes of mild illness in immunocompetent children and adults with rare occurrences of significant morbidity or mortality. Complications are more common in the very young, very old, and those with underlying lung diseases. However, RVIs are increasingly recognized as a cause of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCT) and solid organ transplants (SOTs). Diagnostic techniques for respiratory syncytial virus (RSV), parainfluenza, influenza, and adenovirus have been clinically available for decades, and these infections are known to cause serious disease in transplant recipients. Modern molecular technology has now made it possible to detect other RVIs including human metapneumovirus, coronavirus, and bocavirus, and the role of these viruses in causing serious disease in transplant recipients is still being worked out. This article reviews the current information regarding epidemiology, pathogenesis, clinical presentation, diagnosis, and treatment of these infections, as well as the aspects of clinical significance of RVIs unique to HSCT or SOT.

Management of RSV infections in adult recipients of hematopoietic stem cell transplantation

Respiratory syncytial virus (RSV) is a common cause of seasonal respiratory viral infection in patients who have undergone hematopoietic stem cell transplantation. RSV usually presents as an upper respiratory tract infection in this patient population but may progress rapidly to lower respiratory tract infection. Available therapies that have been used for the treatment of RSV infections are limited to ribavirin, intravenous immunoglobulin, and palivizumab. The use of aerosolized ribavirin, alone or in combination with either palivizumab or intravenous immunoglobulin, remains controversial. In this comprehensive review, we present and discuss the available literature on management of RSV infections in adult hematopoietic stem cell transplantation recipients with a focus on therapeutic modalities and outcomes.