Palivizumab prophylaxis of respiratory syncytial virus infection in high-risk infants

In vitro modelling of intramuscular injection site events

INTRODUCTION

Intramuscular (IM) injections deliver a plethora of drugs. The majority of IM-related literature details dissolution and/or pharmacokinetic (PK) studies, using methods with limited assessments of post-injection events that can impact drug fate, and absorption parameters. Food and Drug Association guidelines no longer require preclinical in vivo modeling in the U.S.A. Preclinical animal models fail to correlate with clinical outcomes, highlighting the need to study, and understand, IM drug fate in vitro using bespoke models emulating human IM sites. Post-IM injection events, i.e. underlying processes that influence PK outcomes, remain unacknowledged, complicating the application of in vitro methods in preclinical drug development. Understanding such events could guide approaches to predict and modulate IM drug fate in humans.

AREAS COVERED

This article reviews challenges in biorelevant IM site modeling (i.e. modeling drug fate outcomes), the value of technologies available for developing IM injectables, methods for studying drug fate, and technologies for training in performing IM administrations. PubMed, Web-of-Science, and Lens databases provided papers published between 2014 and 2024.

EXPERT OPINION

IM drug research is expanding what injectable therapeutics can achieve. However, post-injection events that influence PK outcomes remain poorly understood. Until addressed, advances in IM drug development will not realize their full potential.

Impact of Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are among the leading cause of morbidity and mortality in pediatric hematopoietic stem cell transplant (HCT) and solid organ transplant (SOT) recipients. Transplant recipients remain at high risk for super imposed bacterial and fungal pneumonia, chronic graft dysfunction, and graft failure as a result of RVIs. Recent multicenter retrospective studies and prospective studies utilizing contemporary molecular diagnostic techniques have better delineated the epidemiology and outcomes of RVIs in pediatric transplant recipients and have advanced the development of preventative vaccines and treatment interventions in this population. In this review, we will define the epidemiology and outcomes of RVIs in SOT and HSCT recipients, describe the available assays for diagnosing a suspected RVI, highlight evolving management and vaccination strategies, review the risk of donor derived RVI in SOT recipients, and discuss considerations for delaying transplantation in the presence of an RVI.

Therapeutic Vaccines for Tuberculosis: An Overview

Tuberculosis (TB), caused by Mycobacterium tuberculosis is the world’s deadliest bacterial infection, resulting in more than 1.4 million deaths annually. The emergence of drug-resistance to first-line antibiotic therapy poses a threat to successful treatment, and novel therapeutic options are required, particularly for drug-resistant tuberculosis. One modality emerging for TB treatment is therapeutic vaccination. As opposed to preventative vaccination – the aim of which is to prevent getting infected by M. tuberculosis or developing active tuberculosis, the purpose of therapeutic vaccination is as adjunctive treatment of TB or to prevent relapse following cure. Several candidate therapeutic vaccines, using killed whole-cell or live attenuated mycobacteria, mycobacterial fragments and viral vectored vaccines are in current clinical trials. Other modes of passive immunization, including monoclonal antibodies directed against M. tuberculosis antigens are in various pre-clinical stages of development. Here, we will discuss these various therapeutics and their proposed mechanisms of action. Although the full clinical utility of therapeutic vaccination for the treatment of tuberculosis is yet to be established, they hold potential as useful adjunct therapies.

Neutralizing Monoclonal Antibodies against the Gn and the Gc of the Andes Virus Glycoprotein Spike Complex Protect from Virus Challenge in a Preclinical Hamster Model

Hantaviruses are the etiological agent of hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). The latter is associated with case fatality rates ranging from 30% to 50%. HCPS cases are rare, with approximately 300 recorded annually in the Americas. Recently, an HCPS outbreak of unprecedented size has been occurring in and around Epuyén, in the southwestern Argentinian state of Chubut. Since November of 2018, at least 29 cases have been laboratory confirmed, and human-to-human transmission is suspected. Despite posing a significant threat to public health, no treatment or vaccine is available for hantaviral disease. Here, we describe an effort to identify, characterize, and develop neutralizing and protective antibodies against the glycoprotein complex (Gn and Gc) of Andes virus (ANDV), the causative agent of the Epuyén outbreak. Using murine hybridoma technology, we generated 19 distinct monoclonal antibodies (MAbs) against ANDV GnGc. When tested for neutralization against a recombinant vesicular stomatitis virus expressing the Andes glycoprotein (GP) (VSV-ANDV), 12 MAbs showed potent neutralization and 8 showed activity in an antibody-dependent cellular cytotoxicity reporter assay. Escape mutant analysis revealed that neutralizing MAbs targeted both the Gn and the Gc. Four MAbs that bound different epitopes were selected for preclinical studies and were found to be 100% protective against lethality in a Syrian hamster model of ANDV infection. These data suggest the existence of a wide array of neutralizing antibody epitopes on hantavirus GnGc with unique properties and mechanisms of action.IMPORTANCE Infections with New World hantaviruses are associated with high case fatality rates, and no specific vaccine or treatment options exist. Furthermore, the biology of the hantaviral GnGc complex, its antigenicity, and its fusion machinery are poorly understood. Protective monoclonal antibodies against GnGc have the potential to be developed into therapeutics against hantaviral disease and are also great tools to elucidate the biology of the glycoprotein complex.

Improving the prescribing of palivizumab

AIM

Palivizumab prevents respiratory syncytial virus (RSV) in children at high risk of severe disease. This paper reviews the use and effectiveness of palivizumab at two tertiary paediatric hospitals (hospitals A and B) in New South Wales, Australia.

METHODS

Children prescribed palivizumab during the pre-intervention period, 1 January 2013 until 31 December 2014, were compared with children under 2 years of age who were admitted to paediatric intensive care units (PICUs) with an RSV infection. Eligibility for palivizumab was determined. To improve evidence-based utilisation of palivizumab, a 'streamlined palivizumab individual patient use' (IPU) pro forma was introduced at hospital A during 2015, and its applicability was reviewed.

RESULTS

In the 2 years prior to implementing the streamlined IPU, 47 children received palivizumab, with 87% at hospital A. Of the children at hospital A, 32% did not meet the guidelines, and 32% did not complete the course. While 13% of children admitted to PICU for RSV infection were eligible for palivizumab, none received it prior to admission. In 2015, 16 streamlined IPUs were submitted, and 11 patients received palivizumab. Of these patients, 27% did not meet the guidelines, and 63% did not complete the course. Of the children who received palivizumab during the three RSV seasons, one developed an RSV infection, and none were admitted to PICU.

CONCLUSIONS

Palivizumab is often prescribed without meeting recognised best practice guidelines, and patients eligible are frequently not prescribed palivizumab. The streamlined IPU, implemented in hospital A, excluded patients who did not meet guidelines. The pro forma needs further refinement, and complementary strategies introduced to improve compliance.

Recent advances in the development of subunit-based RSV vaccines

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections causing pneumonia and bronchiolitis in infants. RSV also causes serious illness in elderly populations, immunocompromised patients and individuals with pulmonary or cardiac problems. The significant morbidity and mortality associated with RSV infection have prompted interest in RSV vaccine development. In the 1960s, a formalin-inactivated vaccine trial failed to protect children, and indeed enhanced pathology when naturally infected later with RSV. Hence, an alternative approach to traditional killed virus vaccines, which can induce protective immunity without serious adverse events, is desired. Several strategies have been explored in attempts to produce effective vaccine candidates including gene-based and subunit vaccines. Subunit-based vaccine approaches have shown promising efficacy in animal studies and several have reached clinical trials. The current stage of development of subunit-based vaccines against RSV is reviewed in this article.

Matrix Metalloproteinase-9 Mediates RSV Infection in Vitro and in Vivo

Respiratory Syncytial Virus (RSV) is an important human pathogen associated with substantial morbidity and mortality. The present study tested the hypothesis that RSV infection would increase matrix metalloproteinase (MMP)-9 expression, and that MMP-9 inhibition would decrease RSV replication both in vitro and in vivo. RSV A2 infection of human bronchial epithelial cells increased MMP-9 mRNA and protein release. Cells transfected with siRNA against MMP-9 following RSV infection had lower viral titers. In RSV infected wild-type (WT) mice, MMP-9, airway resistance and viral load peaked at day 2 post infection, and remained elevated on days 4 and 7. RSV infected MMP-9 knockout (KO) mice had decreased lung inflammation. On days 2 and 4 post inoculation, the RSV burden was lower in the MMP-9 KO mice compared to WT controls. In conclusion, our studies demonstrate that RSV infection is a potent stimulus of MMP-9 expression both in vitro and in vivo. Reduction of MMP-9 (via siRNA knockdown, and in MMP-9 KO mice) resulted in decreased viral replication. Our findings suggest MMP-9 is a potential therapeutic target for RSV disease.

Effectiveness of Palivizumab in Preventing RSV Hospitalization in High Risk Children: A Real-World Perspective

Infection with respiratory syncytial virus (RSV) is one of the major causes globally of childhood respiratory morbidity and hospitalization. Palivizumab, a humanized monoclonal antibody, has been recommended for high risk infants to prevent severe RSV-associated respiratory illness. This recommendation is based on evidence of efficacy when used under clinical trial conditions. However the real-world effectiveness of palivizumab outside of clinical trials among different patient populations is not well established. We performed a systematic review focusing on postlicensure observational studies of the protective effect of palivizumab prophylaxis for reducing RSV-associated hospitalizations in infants and children at high risk of severe infection. We searched studies published in English between 1 January 1999 and August 2013 and identified 420 articles, of which 20 met the inclusion criteria. This review supports the recommended use of palivizumab for reducing RSV-associated hospitalization rates in premature infants born at gestational age < 33 weeks and in children with chronic lung and heart diseases. Data are limited to allow commenting on the protective effect of palivizumab among other high risk children, including those with Down syndrome, cystic fibrosis, and haematological malignancy, indicating further research is warranted in these groups.

Palivizumab in preventing respiratory syncytial virus-related hospitalization in high-risk infants

Respiratory syncytial virus (RSV) causes seasonal epidemics (winter or wet-season) of serious lower respiratory tract infections in young infants with subsequent increased frequency of recurrent wheezing during early childhood. Palivizumab is a humanized monoclonal antibody that provides immunoprophylaxis against RSV when administered monthly over the RSV season. It significantly reduced hospitalizations in high-risk infants including preterm infants with and without bronchopulmonary dysplasia and infants with hemodynamically significant congenital heart disease. Since its license in 1998, approximately 36 methodologically different economic studies have been performed to prove cost-effectiveness of the product. The majority of cost-effectiveness analyses revealed costs of palivizumab exceeding anticipated savings from reduced RSV hospitalizations. A minority of studies performed cost-effectiveness analyses using incremental cost-effectiveness ratios as costs per quality-adjusted life-year gained. The wide variability in the results of economic studies with estimates ranging from cost savings to incremental costs of a high order of magnitude with its use is discussed, in the light of the continuing burden of RSV disease, the limited treatment modalities, and the continuing research for a vaccine.

Preventing RSV bronchiolitis in vulnerable infants: the role of palivizumab

As the vast majority of infants tolerate infection with the respiratory syncytial virus [RSV] well and can be managed in the home, most should not be considered for RSV prophylaxis with palivizumab. However, there exists a subset of vulnerable infants in whom the consequences of RSV infection are greater, with an increased likelihood of intensive care admission and mechanical ventilation. These include children born extremely preterm with chronic neonatal lung disease and infants with haemodynamically significant cardiac disease in whom there exists level II evidence to suggest that palivizumab may reduce their risk of acquiring RSV by approximately 50%. The use of palivizumab varies considerably across the world, based largely on economic considerations. This article reviews the strategies developed to fight RSV infection, the evidence for the use of palivizumab and suggests a reasonable approach clinically and economically to the use of palivizumab, proposing its use selectively in the most vulnerable infants during the first six months of life.

Premorbid factors and outcome associated with respiratory virus infections in a pediatric intensive care unit

OBJECTIVES

The purpose of this study was to report the clinical features and outcome of all children with a laboratory proven diagnosis of respiratory virus infection admitted to a university Pediatric Intensive Care Unit (PICU).

METHODS

Retrospective study between January 2003 and April 2007 was carried out in the PICU. Every child with a laboratory-confirmed viral infection was included.

RESULTS

54 viruses were identified in 49 children (27 M, 22 F) over a 52-month period. The three respiratory virus species, respiratory syncytial virus (RSV) (n = 17), influenza (n = 13) and parainfluenza (n = 12), accounted for 86% of these 49 cases. PICU admissions due to influenza A (n = 10) were more common than influenza B (n = 3), whereas parainfluenza type 3 (n = 7) was the commonest subtype of parainfluenza infection. Comparing these three common viruses, the mean age of children admitted with RSV was lower than with influenza or parainfluenza (1.2 years vs. 5.6 years vs. 2.4 years, P = 0.003). Pre-existing conditions such as prematurity and chronic lung disease were only present in children with RSV infection. These respiratory viruses caused both upper (croup) and lower respiratory tract diseases (bronchiolitis, pneumonia). Extrapulmonary presentations were less prevalent and included encephalitis, seizures, cardiac arrest, coexisting diabetes ketoacidosis and acute lymphoblastic leukemia. One patient with RSV and another with influenza A died during their PICU stay. Nearly half of these patients required ventilatory support or received systemic corticosteroids, and 88% received initial broad spectrum antibiotic coverage. Approximately one in five of them had nebulised adrenaline, airway endoscopies or bacterial co-infections. Adenovirus was isolated in four patients and two (both with adenovirus type 3) died during the PICU stay.

CONCLUSIONS

In PICU, respiratory viral infections were associated with significant morbidity and life-threatening conditions.

Cost, causes and rates of rehospitalization of preterm infants

OBJECTIVE

To examine hospital readmissions for premature infants during the first year of life.

STUDY DESIGN

The California maternal and newborn/infant hospital discharge records were examined for subsequent readmission during the first year of life for all newborns from 1992 to 2000. Discharge diagnoses, hospital days, demographic data and hospital charges for infants born preterm (<36 weeks gestation) were identified and evaluated.

RESULT

About 15% of preterm infants required at least one rehospitalization within the first year of life (average cost per readmission 8,468 dollars, average annual cost in excess of 41 million dollars). Infants with gestational age <25 weeks had the highest rate of readmission (31%) and longest average length of stay (12 hospital days). The largest cohort, infants born at 35 weeks gestation, had the highest total cost of readmission (92.9 million dollars). The most common cause of rehospitalization was acute respiratory disease. There was no decrease in the number or cost of readmissions of premature infants for respiratory syncytial virus infections following the introduction of palivizumab in 1998.

CONCLUSION

After initial discharge, premature infants continue to have significant in-patient health-care needs and costs.

Administration of the first dose of palivizumab immunoprophylaxis against respiratory syncytial virus in infants before hospital discharge: what is the evidence for its benefit?

BACKGROUND

Palivizumab is 1 of 2 agents used to prevent severe lower respiratory tract disease due to respiratory syncytial virus (RSV) infection. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommend administering the first dose of RSV immunoprophylaxis to eligible infants before hospital discharge. Unfortunately, third-party payers frequently do not separately reimburse administration of this therapy to hospitalized infants.

OBJECTIVE

Because palivizumab is commonly used to provide RSV immunoprophylaxis, we systematically reviewed all published data on this drug to determine whether the evidence supports the recommendation of administering the first dose before hospital discharge.

METHODS

MEDLINE was searched for all articles published in English from January 1, 1996, to October 31, 2003, using the search terms palivizumab and Synagis, and the following data were extracted onto a standardized form: author(s), year of publication, study design, patient population, sample size, criteria used for administration of RSV prophylaxis, location of palivizumab prophylaxis (inpatient or outpatient), parental satisfaction with administration of prophylaxis, incidence of RSV infection, and hospitalization rates for RSV. All selected publications were reviewed to determine whether they reported differences in the incidence of RSV infection or hospitalization in patients who received palivizumab before discharge compared with those who received it after discharge. Only those publications that specifically documented administration of the first dose of palivizumab before hospital discharge were included in the final analysis.

RESULTS

Six of the 166 studies reviewed met the selection criteria. Although all 6 studies reported reduced RSV hospitalization rates with palivizumab prophylaxis, no study directly compared inpatient and outpatient administration with regard to parental satisfaction or rates of RSV infection or hospitalization. Furthermore, based on the data in these studies, it was not possible to detect any differences in parental satisfaction or rates of RSV infection or hospitalization between the 2 locations of administration.

CONCLUSIONS

Based on our literature review, there is no evidence to support the recommendation that palivizumab be administered before hospital discharge in every infant who meets the criteria for RSV immunoprophylaxis. Eligible infants may be given the initial dose of RSV prophylaxis as outpatients, reducing the cost to institutions that currently provide palivizumab before hospital discharge.

Pathogenesis of Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is recognized as the most important cause of serious lower respiratory tract illness in infants and young children worldwide causing repeat infections throughout life with serious complications occurring in the elderly and immune compromised patient. The level of disease pathogenesis associated with RSV infection is balanced between virus elimination and the nature of the immune response to infection. The innate and adaptive immune responses to RSV infection are not fully elucidated; however, significant progress has been made in understanding the virus-host relationship and mechanisms associated with disease pathogenesis. This review summarizes important aspects of these findings, and provides current perspective on processes that may contribute to RSV disease pathogenesis.

Compliance with prophylaxis for respiratory syncytial virus infection in a home setting

BACKGROUND

Respiratory syncytial virus (RSV) is the most common respiratory pathogen in infancy and childhood.

OBJECTIVE

To compare the compliance and biologic efficacy of a home health care agency dosing-compliance program to treatment provided in a physician's office setting during a single RSV season (November to May). METHODS.: AAP guidelines were used to identify neonates who were eligible for RSV prophylaxis before discharge from a neonatal intensive care unit setting. Parents were asked to choose to receive the recommended treatment for their child either in their pediatrician's office setting or through a sequence of periodic nursing visits to their home. All home health care records were reviewed for demographics, number of doses received and hospitalization rate. Pediatricians office records were surveyed by telephone interview of their office staff and parents. Compliance data were calculated based on actual monthly injections given during the RSV season.

RESULTS

We followed prospectively 1446 infants who received palivizumab during a single RSV season (November 1, 2000 through April 30, 2001). Of these infants 67% (969 of 1446) received their monthly injections in the home setting where 98% of the doses were given on schedule. In contrast 477 infants (33%) received their injections in a pediatrician's office (parent's choice) with a compliance of only 89% for completion of all recommended doses (P < 0.001 vs. home setting). There were 9 RSV hospitalizations (0.93%) in the home setting group and 8 RSV hospitalizations (3.57%) in the office setting (P < 0.001). More parents indicated that the in-home prophylaxis program was more convenient than was true for those receiving treatment in the physician's office setting (P < 0.01).

CONCLUSIONS

Better compliance with home injections was associated with a decrease in the hospitalization rate for RSV with a higher degree of parental satisfaction.

Effectiveness of drug therapies to treat or prevent respiratory syncytial virus infection-related morbidity

Respiratory syncytial virus (RSV) infection causes a huge burden to the health service, as it results in a large number of in-patient days each year and increases the risk of asthma in childhood. In the acute phase, therapy is supportive as bronchodilators and corticosteroids have resulted, at best, only in short-term benefits; promising treatments for ventilated patients, such as exogenous surfactant, require further testing. Passive immunoprophylaxis reduces hospital admission in high risk groups. In the prevention of chronic respiratory morbidity following RSV infection, however, studies are needed to determine whether immunoprophylaxis will have a useful role and to identify which drug treatment will be most cost-effective.

Impacto potencial y análisis coste-eficacia de la profilaxis con palivizumab, en la prevención de bronquiolitis, en prematuros menores de 33 semanas de gestación

INTRODUCTION

Respiratory syncytial virus (RSV) is the main cause of bronchiolitis in children aged less than 2 years. The effectiveness of palivizumab has recently been reported in several clinical trials.

OBJECTIVE

The aim of this study was to evaluate the hypothetical impact of a treatment strategy using palivizumab for the prevention of bronchiolitis in premature infants.

METHODS

Neonates born in our hospital between January 1995 and December 1998 who were admitted for bronchiolitis were included. Using information from the Impact-RSV study, the effects and impact of different cut-off points in the gestational age of the study group were measured. Cost-effectiveness analysis included the cost of hospitalization as well as the direct cost of palivizumab prescriptions.

RESULTS

Of 7,766 newborn infants, 56 had a gestational age of < or =32 weeks. Of these, bronchiolitis was diagnosed in eight infants (14.28%), and RSV was isolated in seven (14.28%). After hypothetical prophylaxis in premature infants the best results were obtained in the group with a gestational age of 30 weeks. In this group the relative risk of admission for bronchiolitis was 12.1 (95% CI: 4.8-30.5) and treatment would be required in nine infants to avoid one admission (cost Euros 12,915), with a cost 3.8 times greater than the current cost, without prophylaxis.

CONCLUSIONS

Measurement of the impact and cost-effectiveness analysis of palivizumab prophylaxis provides a useful method for determining recommendations for the prevention of bronchiolitis in premature infants.