Nirsevimab-alip Injection (Beyfortus)
August 30, 2023 3 minutes read
By William Elliott, MD, FACP, and James Chan, PharmD, PhD
Dr. Elliott is Assistant Clinical Professor of Medicine, University of California, San Francisco.
Dr. Chan is Associate Clinical Professor, School of Pharmacy, University of California, San Francisco.
The FDA has approved a drug to prevent respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants.1 Nirsevimab is a recombinant human immunoglobulin G1 kappa monoclonal antibody directed at the prefusion conformation of the RSV fusion protein.2 The agency granted a fast-track breakthrough therapy designation and an accelerated priority review. The solution will be distributed as Beyfortus.
INDICATIONS
Nirsevimab can be prescribed to prevent RSV lower respiratory tract disease in neonates and infants born during or entering their first RSV season. The solution also can be administered to children up to age 24 months who remain vulnerable to severe disease through their second RSV season.2
DOSAGE
For patients weighing less than 5 kg, administer 50 mg by intramuscular injection.2 For patients who weigh 5 kg or heavier, administer 100 mg.2 Nirsevimab is available as 50 mg/0.5 mL in single-dose, prefilled syringes.
POTENTIAL ADVANTAGES
Nirsevimab neutralizes both RSV A and B strains. One dose of nirsevimab provides protection, leading to fewer medically attended, RSV-associated lower respiratory tract infections.2-4 The elimination half-life is approximately 71 days, and protection is maintained through 150 days — or approximately the length of the RSV season.2-4 Current FDA-approved therapy, palivizumab, requires monthly administration throughout the RSV season. Surveillance evidence suggests the emergence of variants observed with reduced susceptibility to nirsevimab appears to be low/rare.2
POTENTIAL DISADVANTAGES
Nirsevimab is not a vaccine. It provides passive, not active, immunization. As a human IgGI monoclonal antibody, hypersensitivity reactions, including anaphylaxis, can occur.2 The common adverse reactions were rash (0.9% vs. 0.6% for placebo) and injection site reactions (0.3% vs. 0%).2
COMMENTS
The safety and efficacy of nirsevimab were evaluated in three studies: one in preterm infants, one in late-term and term infants, and one in preterm infants and infants with chronic lung disease of prematurity or hemodynamically significant chronic heart disease (with palivizumab as an active control).2-4
In the first study, participants (born at 29 weeks or after to < 35 weeks gestational age) were randomized to receive nirsevimab (n = 969) or placebo (n = 484).2,3 The primary efficacy endpoint was the incidence of medically attended healthcare visits for RSV lower respiratory tract infection (MA LRTI) caused by RT-PCR-confirmed RSV, characterized predominately as bronchiolitis or pneumonia through 140 days after dosing. MA LRTI incidences were 2.6% for nirsevimab and 9.5% for placebo (efficacy, 70.1%; 95% CI, 52.3-81.2).
In the second study, 994 participants were randomized to nirsevimab, and 496 were randomized to placebo. MA LRTI rates were 1.2% for nirsevimab and 5% for placebo (efficacy, 74.9%; 95% CI, 50.6-87.3). In the third study, participants were randomized to nirsevimab (one dose with four monthly placebo doses) or palivizumab (five once-monthly doses).2 MA LRTI incidences were 0.6% for nirsevimab and 1% for palivizumab.
CLINICAL IMPLICATIONS
Most children contract RSV infection by age 2 years, with an estimated 58,000 to 80,000 children younger than age 5 years requiring hospitalization.5 There is no treatment; before nirsevimab, palivizumab was the only preventive option. However, palivizumab requires monthly administration through the RSV season. Nirsevimab is an improvement, providing passive immunity with one dose per season and appears to be at least as effective as palivizumab. On Aug. 3, the CDC’s Advisory Committee on Immunization Practices recommended all infants younger than age 8 months receive nirsevimab and that infants ages 8 to 19 months receive a second dose to help them through their second RSV season if they are living with underlying health issues that put them at higher risk for hospitalization. The expected price is $495 per injection.
REFERENCES
1. U.S. Food & Drug Administration. FDA approves new drug to prevent RSV in babies and toddlers. July 17, 2023.
2. Beyfortus prescribing information. July 2023.
3. Griffin MP, Yuan Y, Takas T, et al. Single-dose nirsevimab for prevention of RSV in preterm infants. N Engl J Med 2020;383:415-425.
4. Hammitt LL, Dagan R, Yuan Y, et al. Nirsevimab for prevention of RSV in healthy late-preterm and term infants. N Engl J Med 2022;386:837-846.
5. Centers for Disease Control & Prevention. RSV in infants and young children. Page last reviewed Aug. 4, 2023.
Nirsevimab can be prescribed to prevent respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants born during or entering their first RSV season.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content