Use of palivizumab in Germany: data from 2002-2007

Challenges in the prevention or treatment of RSV with emerging new agents in children from low- and middle-income countries

INTRODUCTION

Respiratory syncytial virus (RSV) causes approximately 120,000 deaths annually in children <5 years, with 99% of fatalities occurring in low- and middle-income countries (LMICs).

AREAS COVERED

There are numerous RSV interventions in development, including long-acting monoclonal antibodies, vaccines (maternal and child) and treatments which are expected to become available soon. We reviewed the key challenges and issues that need to be addressed to maximize the impact of these interventions in LMICs. The epidemiology of RSV in LMICs was reviewed (PubMed search to 30 June 2020 inclusive) and the need for more and better-quality data, encompassing hospital admissions, community contacts, and longer-term respiratory morbidity, emphasized. The requirement for an agreed clinical definition of RSV lower respiratory tract infection was proposed. The pros and cons of the new RSV interventions are reviewed from the perspective of LMICs.

EXPERT OPINION

We believe that a vaccine (or combination of vaccines, if practicable) is the only viable solution to the burden of RSV in LMICs. A coordinated program, analogous to that with polio, involving governments, non-governmental organizations, the World Health Organization, the manufacturers and the healthcare community is required to realize the full potential of vaccine(s) and end the devastation of RSV in LMICs.

Palivizumab use in infants with Down syndrome-report from the German Synagis™ Registry 2009-2016

Infants with Down syndrome (DS) face an increased risk of respiratory tract infections. Recent studies describe DS as independent risk factor for a complicated clinical course in infants with respiratory syncytial virus (RSV) infection. The prospective observational German Synagis™ Registry comprises data from 249 children below 25 months of age with DS and palivizumab prophylaxis 2009-2016 (1191 administrations; mean 4.8 per patient and season). The median gestational age and the birth weight in patients without and with DS were 31 versus 37 weeks (P < 0.001) and 1590 versus 2750 g, respectively (P < 0.001). Patients with DS significantly more often had congenital heart disease (CHD), siblings in kindergarten or school, treatment with oxygen at home, immunodeficiency, and neuromuscular impairment. The RSV-related hospitalization rate in patients with DS was 1.20%; the hospitalization rate in patients without DS was 0.71%.

CONCLUSION

Data from 249 children with DS receiving palivizumab prophylaxis in seven consecutive RSV seasons (2009-2016) in Germany reveal important differences between patients with and without DS concerning the main indication for palivizumab use and additional risk factors. Bearing in mind the limitations of an uncontrolled postmarketing observational study, the results confirm the field effectiveness of palivizumab prophylaxis in this special population. What is Known: • Recent studies describe the Down syndrome as independent risk factor for a complicated clinical course in infants with RSV infection. What is New: • Compared with other infants receiving palivizumab prophylaxis, patients with Down syndrome significantly more often had congenital heart disease, siblings in kindergarten or school, treatment with oxygen at home, immunodeficiency, and neuromuscular impairment. • In infants with palivizumab prophylaxis breakthrough, RSV-related hospitalization rates were not significantly higher in those with Down syndrome.

Past, Present and Future Approaches to the Prevention and Treatment of Respiratory Syncytial Virus Infection in Children

INTRODUCTION

The REGAL (RSV Evidence - A Geographical Archive of the Literature) series has provided a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This seventh and final publication covers the past, present and future approaches to the prevention and treatment of RSV infection among infants and children.

METHODS

A systematic review was undertaken of publications between January 1, 1995 and December 31, 2017 across PubMed, Embase and The Cochrane Library. Studies reporting data on the effectiveness and tolerability of prophylactic and therapeutic agents for RSV infection were included. Study quality and strength of evidence (SOE) were graded using recognized criteria. A further nonsystematic search of the published literature and Clinicaltrials.gov on antiviral therapies and RSV vaccines currently in development was also undertaken.

RESULTS

The systematic review identified 1441 studies of which 161 were included. Management of RSV remains centered around prophylaxis with the monoclonal antibody palivizumab, which has proven effective in reducing RSV hospitalization (RSVH) in preterm infants < 36 weeks' gestational age (72% reduction), children with bronchopulmonary dysplasia (65% reduction), and infants with hemodynamically significant congenital heart disease (53% reduction) (high SOE). Palivizumab has also shown to be effective in reducing recurrent wheezing following RSVH (high SOE). Treatment of RSV with ribavirin has conflicting success (moderate SOE). Antibodies with increased potency and extended half-life are currently entering phase 3 trials. There are approximately 15 RSV vaccines in clinical development targeting the infant directly or indirectly via the mother.

CONCLUSION

Palivizumab remains the only product licensed for RSV prophylaxis, and only available for high-risk infants. For the general population, there are several promising vaccines and monoclonal antibodies in various stages of clinical development, with the aim to significantly reduce the global healthcare impact of this common viral infection.

FUNDING

AbbVie.

Respiratory syncytial virus associated hospitalizations in preterm infants of 29 to 32 weeks gestational age using a risk score tool for palivizumab prophylaxis

To evaluate the efficacy of palivizumab in infants of 29 to 32 weeks of gestational age (GA) based on a risk score tool developed for Austria. Retrospective single-center cohort study including all preterm infants of 29 (+0) to 32 (+6) weeks of GA born between 2004 and 2012 at a tertiary care university hospital. Data on RSV-related hospitalizations over the first 2 years of life were analyzed and compared between those having received palivizumab and those without. The study population was comprised of 789 of 816 screened infants, of whom 262 (33%) had received palivizumab and 527 (67%) had not. Nine of 107 rehospitalizations (8.4%) in the palivizumab group compared to 32 of 156 rehospitalizations (20.5%) in the group without prophylaxis were tested RSV-positive (p = 0.004; OR 0.356 [CI 90% 0.184-0.689]). Proven and calculated RSV hospitalization rate was 3.1% (8/262) in the palivizumab group and 5.9% (31/527) in the group without (p = 0.042; OR 0.504 [CI 90% 0.259-0.981]). Increasing number of risk factors (up to three) increased the RSV hospitalization rate in infants with (6.1%) and without (9.0%) prophylaxis. RSV-associated hospitalizations did not differ between groups with regard to length of stay, severity of infection, age at hospitalization, demand of supplemental oxygen, need for mechanical ventilation, and admission rate to the ICU. A risk score tool developed for infants of 29 to 32 weeks of gestational age led to a reduction of RSV-associated hospitalizations without influencing the severity of disease.

Respiratory Syncytial Virus Infection Rates with Limited Use of Palivizumab for Infants Born at 29 to 31+6/7 Weeks Gestational Age

BACKGROUND

Immunoprophylaxis with palivizumab can reduce respiratory syncytial virus (RSV) infections and hospitalizations. Criteria in British Columbia limit the use of palivizumab to infants born at 29 to 31+6/7 weeks gestational age, which differ from guidelines of the American Academy of Pediatrics (AAP) and the Canadian Paediatric Society (CPS).

OBJECTIVE

To determine whether the limited use of palivizumab affected the frequency of hospital visits by RSV-positive infants (termed "RSV-positive hospital visits") who received approval for palivizumab and those who met the AAP/CPS criteria but did not receive approval for palivizumab.

METHODS

Data sets were generated for the period May 1, 2008, to April 30, 2011, to identify infants with gestational age of 29 to 31+6/7 weeks who were born in or transferred to the Fraser Health authority, RSV-positive results for infants less than 12 months of age who had visited Fraser Health sites and BC Children's Hospital, and palivizumab approvals. Infants were matched across these 3 data sets through their personal health numbers.

RESULTS

The study included 359 infants born at 29 to 31+6/7 weeks, of whom 297 met the AAP/CPS criteria. However, only 46 of these 297 received approval for palivizumab according to the BC criteria. Sixteen (4.5%) of the 359 infants had RSV-positive hospital visits during the RSV season (November through March). Of the 46 infants who received approval for palivizumab, 2 (4.3%) had RSV-positive hospital visits, and of the 251 who met the AAP/CPS criteria but did not receive palivizumab approval, 14 (5.6%) had RSV-positive hospital visits. Of the 359 infants, 6 (1.7%) had RSV-positive results while admitted to the neonatal intensive care unit, and 10 (2.8%) tested positive for RSV during a subsequent hospital visit.

CONCLUSIONS

The frequency of RSV-positive hospital visits did not differ between infants who received and those who did not receive approval for palivizumab in the Fraser Health authority. Limited use of palivizumab for RSV prophylaxis led to reasonable rates of RSV-positive hospital visits in the study population.

Palivizumab Adherence and Outcomes in Canadian Aboriginal Children

BACKGROUND

Aboriginal infants are at risk for serious respiratory infection.

OBJECTIVE

To determine the hazard rate (HR) for respiratory-related illness (RIH) and respiratory syncytial virus (RSV) specific infection hospitalization (RSVH) in Aboriginal versus non-Aboriginal children receiving palivizumab and the effect of adherence on hospitalization.

METHODS

Palivizumab recipients in the Canadian registry from 2005 to 2014 were included. Adherence was determined by the number of palivizumab doses received during the RSV season and interdose time interval. Adherence proportions between groups were compared by χ test. Cox proportional hazard analysis determined the effect of Aboriginal status and adherence on the risk of RIH and RSVH.

RESULTS

Aboriginal infants comprised 3.6% (701/19,235) of the registry. HR was 1.6 [95% confidence interval (CI): 1.3-2.0, P < 0.001] and 1.2 (95% CI: 0.7-2.2, P = 0.383) for RIH and RSVH. Aboriginal infants were 62.8% and 63.3% adherent with all recommended injections and within stipulated time intervals, respectively, whereas 81.9% (χ = 162.45, df = 1, P < 0.001) and 72.4% (χ = 27.35, df = 1, P = 0.002) of non-Aboriginal infants were correspondingly adherent. Only 39.9% of Aboriginals were perfectly adherent (adherent to total number and injection intervals), compared with 61.7% of non-Aboriginals (χ = 133.89, df = 1, P < 0.001). Even after adjustment for known risk factors, being Aboriginal and nonadherent was associated with higher RIH hazard (HR = 1.4, 95% CI: 1.1-1.8; HR = 1.3, 95% CI: 1.1-1.4, P = 0.004), respectively. Aboriginals nonadherent with interdose intervals had a 2.2-fold increased HR for RSVH (HR = 2.2, 95% CI: 1.2-4.2, P = 0.015).

CONCLUSIONS

Prophylaxed Aboriginal infants have a significantly increased RIH and RSVH hazard than non-Aboriginal infants. Improving adherence especially interdose frequency may further reduce hospitalizations in this vulnerable population.

Adherence to Palivizumab for Respiratory Syncytial Virus Prevention in the Canadian Registry of Palivizumab

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections in infants. Palivizumab, a means of passive prophylaxis, relies on patient adherence to ensure therapeutic effectiveness. The objective of this study is to evaluate the association between adherence and the incidence of RSV-associated outcomes and to identify demographic factors that may impact adherence.

METHODS

Infants were recruited into the Canadian registry of palivizumab (CARESS) with parental consent. Monthly interviews collected information on palivizumab administration and RSV-associated outcomes. An infant was considered adherent if they received all of their expected injections or ≥5 injections within the appropriate interdose intervals.

RESULTS

Nineteen thousand two hundred thirty-five infants received a total of 83,447 injections from October 2005 to May 2014. Adherence was more likely in infants with higher maternal education and in those with siblings. Adherence was less likely in infants of aboriginal descent, with mothers who smoke and older infants. Adherence was significantly associated [odds ratio (95% confidence interval), P value] with a lower incidence of RSV infection [0.74 (0.60-0.93), 0.01] but not with RSV-associated hospitalization. However, in those hospitalized for RSV, adherence was significantly associated with the incidence of intubation and duration of hospitalization, intensive care stay and respiratory support.

CONCLUSIONS

Adherence may have implications in children with less severe RSV infections and those who are already hospitalized for a RSV infection. Our study also identifies subpopulations that are more likely to be nonadherent to palivizumab therapy. Future studies should aim to validate the relationship among adherence, palivizumab levels and RSV-associated outcomes.

Serious Adverse Events in the Canadian Registry of Children Receiving Palivizumab (CARESS) for Respiratory Syncytial Virus Prevention

OBJECTIVES

To evaluate the safety and tolerability of palivizumab for RSV prophylaxis in high-risk children in everyday practice.

METHODS

High-risk children prophylaxed against RSV infection were recruited into a prospective, observational, Canadian RSV Evaluation Study of Palivizumab (CARESS) registry with active, serious adverse event (SAE) monitoring from 2008 to 2013. SAE reports were systematically collected and assessed for severity and relationship to palivizumab. Data were analyzed by Chi-square or Fisher Exact Tests to examine group differences in proportions.

RESULTS

13025 infants received 57392 injections. Hospitalizations for respiratory-related illness (RIH) were reported in 915 patients, and SAEs other than RIH were reported in 52 patients. Of these, 6 (0.05%) patients had a total of 14 hypersensitivity reactions that were deemed possibly or probably related to palivizumab (incidence: 2.8 per 10,000 patient-months). The SAEs of 42 patients were assessed as not related to palivizumab. SAEs in the remaining 4 patients were not classifiable as their records were incomplete. There were no significant demographic predictors of SAE occurrence.

CONCLUSIONS

Under active surveillance, a small proportion of infants in the CARESS registry experienced SAEs that had a potential relationship with palivizumab and these appeared to be unpredictable in terms of onset. Palivizumab appears to be a safe and well-tolerated antibody for RSV prophylaxis in high-risk children in routine practice.

Safety and Effectiveness of Palivizumab in Children at High Risk of Serious Disease Due to Respiratory Syncytial Virus Infection: A Systematic Review

INTRODUCTION

Lower respiratory tract infection (LRTI) is the leading cause of infant mortality globally in post-neonatal infants (i.e., 28-364 days of age). Respiratory syncytial virus (RSV) is the most commonly identified pathogen for infant LRTI and is the second most important cause of death in post-neonatal infants. Despite 50 years of RSV vaccine research, there is still no approved vaccine. Therefore, passive immunity with the monoclonal antibody palivizumab is the sole regulatory-approved option for the prevention of serious LRTI caused by RSV in pediatric patients at high risk of RSV disease.

METHODS

We conducted a comprehensive systematic literature review of randomized controlled trials (RCTs), open-label non-comparative clinical trials, and prospective observational studies/registries, and summarized the evidence related to the safety, efficacy, and effectiveness of palivizumab.

RESULTS

The efficacy of palivizumab, as measured by the relative reduction in RSV-related hospitalization rate compared with placebo ranged from 39% to 78% (P < 0.05) in the 2 pivotal RCTs. A meta-analysis of the RSV-related hospitalization rate from 5 randomized placebo-controlled trials yielded an overall odds ratio of 0.41 (95% CI, 0.31-0.55) in favor of palivizumab prophylaxis over placebo (P < 0.00001). Low rates of RSV-related hospitalizations were observed in palivizumab recipients consistently over time in more than 42,000 pediatric subjects across 7 RCTs, 4 open-label non-comparative trials, and 8 observational studies/registries conducted in 34 countries. In addition, among palivizumab-prophylaxed subjects with breakthrough RSV LRTI, rates of intensive care unit admission and mechanical ventilation from RSV hospitalization also were low and consistent across studies. With respect to safety, no differences were observed between palivizumab and placebo in the blinded RCTs.

CONCLUSION

Rates of RSV hospitalizations and RSV hospitalization-related endpoints in pediatric subjects who received prophylaxis with palivizumab were low and constant over time and across RCTs, open-label non-comparative trials, and observational studies/registries.

Respiratory-related hospitalizations following prophylaxis in the Canadian registry for palivizumab (2005-2012) compared to other international registries

Respiratory syncytial virus (RSV) infection occurs commonly in infants aged ≤2 years, and severe infection results in hospitalization with accompanying morbidity and mortality. Palivizumab has been available for prophylaxis for the past 15 years. Prospective data on patients who received palivizumab from 2005 to 2012 has been assembled in the Canadian registry (CARESS) to document utilization, compliance, and health outcomes in both hospital and community settings. Long-term data is necessary to evaluate the impact of palivizumab on the incidence of RSV infections, minimize healthcare resources, and identify which infant subpopulations are receiving prophylaxis. A database search was also conducted for similar information from published registries, and hospitalization rates were compared to results from randomized clinical trials (RCTs).Overall hospitalization rates (percent; range) for respiratory-related illnesses and RSV-specific infection in infants who meet standard indications for prophylaxis were 6.6 (3.3-7.7) and 1.55 (0.3-2.06), respectively, in CARESS, which closely aligns with registry data from 4 other countries, despite the former comprising the largest cohort of complex patients internationally. Overall RSV-related hospitalization rates were lower across registries compared to equivalent patients in RCTs. Registry data provides valuable information regarding real-world experience with palivizumab, while facilitating the genesis of new research themes.

Three monthly doses of palivizumab are not adequate for 5-month protection: a population pharmacokinetic analysis

Recent guidelines in British Columbia, Canada have suggested that the use of a maximum of 3 monthly doses of palivizumab 15 mg/kg intramuscularly for RSV immunoprophylaxis of high risk infants born prior to the RSV season is adequate to provide protection against severe RSV disease for a 5-month RSV season. Efficacy was established, however, with 2 large, randomized controlled clinical studies using 5 monthly doses of immunoprophylaxis. To evaluate the differences in expected palivizumab exposures between the 2 dosing regimens (3 vs 5 monthly doses across a 5-month period), we used a population pharmacokinetic (PK) model that was developed using palivizumab PK data collected from 22 clinical studies with a total of 1800 subjects. This model adequately described observed palivizumab concentrations from the different pediatric studies and was subsequently used to simulate expected palivizumab serum concentrations for 3 monthly doses compared with 5 monthly doses in children younger than 24 months with chronic lung disease of prematurity and infants younger than 6 months postnatal age who were born at ≤ 35 weeks gestational age. Results from the population PK model indicated lower serum concentrations of palivizumab during the fourth and fifth months, after an abbreviated 3-monthly-dose regimen when compared with the mean trough concentrations seen with the 5-monthly-dose regimen studied in the pivotal clinical trials in premature infants. Specifically, during the fourth and fifth months, 52% and 85%, respectively, would have levels below the lowest concentration (fifth percentile) in those receiving the 5-monthly-dose regimen. Simulations using this model did not support a 3-monthly-dose regimen to protect against severe RSV disease during the typical 5-month season.