Research Supports Efficacy, Safety of Palivizumab Preventing Lower Respiratory Tract Infections by RSV

Palivizumab (Synagis) is an effective treatment option for preventing serious lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) in infants and young children at high-risk of RSV disease, according to a study published in the American Journal of Perinatology. Palivizumab is a humanized monoclonal antibody approved by the FDA to prevent serious LRTI caused by RSV.

The drug is indicated for patients with a history of premature birth (≤35 weeks gestational age) and ≤6 months of age at the beginning of RSV season; patients with bronchopulmonary dysplasia (BPD) requiring medical treatment within the previous months and ≤24 months of age at the beginning of RSV season; and patients with hemodynamically significant congenital heart disease (hs-CHD) and ≤24 months of age at the beginning of RSV season. The study authors noted that the recommendations for RSV immunoprophylaxis have changed since palivizumab was approved and current clinical practice may not reflect the drug’s original indications.

To evaluate the evidence regarding use of palivizumab, the study authors aimed to summarize and update all available evidence on the efficacy and safety of the drug in the interventional and real-world clinical practice settings. The investigators conducted a systematic review of phase 3 trials and observational studies according to the Population, Intervention, Comparator, Outcome, Timing, Setting approach. The study’s outcomes of interest in the indicated patient population included RSV-related hospitalization, admission to intensive care unit (ICU), need for mechanical ventilation, treatment-related adverse events (AEs) and RSV-related deaths.

The study showed that RSV-related hospitalization rates were significantly lower in patients administered palivizumab prophylaxis compared to placebo for each of the indicated populations. They found that RSV-related hospitalization rates after palivizumab prophylaxis in phase 3 trials were 1.8% in premature infants and 7.9% in children with BPD, which were significantly lower than rates observed in patients administered a placebo.

In the real-world setting, the investigators found similar hospitalization rates (0.7%-4.0% in premature infants [16 studies] and 0%-5.5% in patients with BPD [10 studies]), whereas ICU admission was reported in 0% to 33.3% of patients hospitalized for RSV. In clinical trials, RSV-related mortality rates were 0.2% and 0.3%, whereas AEs were reported in 11% of premature and/or BPD patients and 7.2% of hs-CHD patients, which primarily consisted of injection site reaction, fever, and diarrhea. These results were similar to those found in observational studies.

In the IMpact trial, which included premature infants and patients with BPD, the average hospital length of stay was significantly lower in patients administered palivizumab compared with placebo at 36.4 and 62.6 days per 100 children, respectively. The study authors observed similar results in patients with hs-CHD, with a total number of hospitalization days of 57.4 and 129.0 per 100 children, respectively, in the treated and placebo arms, which corresponds to a statistically significant decrease of 56% associated with the use of palivizumab (p=0.003).

The authors concluded that this systematic review supports the efficacy and safety of palivizumab in the indicated populations.

“In the clinical trial setting, rates of RSV-related hospitalization following prophylaxis with palivizumab varied according to indication, with lower rates observed in premature infants than in the BPD or hs-CHD population and were significantly lower compared to placebo,” the study authors wrote. “Similarly, in observational studies for all approved indications, the use of palivizumab was found to significantly reduce RSV-related hospitalizations compared to untreated patients. For all subpopulations of interest, RSV-related hospitalization rates in patients treated with palivizumab were similar to those reported in the 2014 systematic review. These findings support the effectiveness of palivizumab in preventing RSV infection and associated complications in patients at high risk for severe RSV disease and are consistent with findings from the 2014 systematic review.”

Reference

Gonzales T, Bergamasco A, Cristarella T, Goyer C, Wojdyla M, Oladapo A, Sawicky J, Yee J, Moride Y. Effectiveness and Safety of Palivizumab for the Prevention of Serious Lower Respiratory Tract Infection Caused by Respiratory Syncytial Virus: A Systematic Review. Am J Perinatol. 2022 Nov 30. doi: 10.1055/a-1990-2633. Epub ahead of print. PMID: 36452969.