Baloxavir marboxil recommended as post-exposure prophylaxis to influenza by EMA

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Medical writer: Kirsty LEE | Last updated: 11th December 2020 | In: Gastrointestinal Cancer, Lung Cancer, Oncology, Targeted Therapies

Article Keywords

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Seasonal influenza is common between January to March, and July to August in Hong Kong.¹ Baloxavir marboxil is the first influenza antiviral with a novel mechanism of action to be approved in almost two decades, and was registered for use in Hong Kong in February 2019.^2,3 It is approved for the treatment of acute uncomplicated influenza in patients 12 years of age and older, who have been symptomatic for no more than 48 hours.² It was recently approved as post-exposure prophylaxis for influenza by both the US FDA and EMA, based on the results of the BLOCKSTONE study.^4-6

The multicentre, double-blind, randomised, placebo-controlled BLOCKSTONE trial evaluated the postexposure prophylactic efficacy of baloxavir marboxil in household contacts of index patients with confirmed influenza during the 2018-2019 flu season in Japan.⁶ Index patients were defined as the first documented case of influenza in a household, on basis of a positive rapid influenza diagnostic test.⁶ In total 752 participants were classified as asymptomatic close contacts who had lived in the same household as the index patient or at least 48 hours before enrolment and were randomised 1:1 to receive either baloxavir or matching placebo.⁶ The primary efficacy endpoint was laboratory-confirmed clinical influenza, and key secondary endpoints included RT-PCR confirmed illness, and RT-PCR confirmed influenza virus infection regardless of fever and symptoms.⁶ Risk ratios were adjusted for randomization factors (time from onset of illness, type of antiviral treatment of index patient, and age of the participant [continuous variable]).⁶

The majority of participants (72.5%) received baloxavir or placebo within 24 hours after onset of illness in the index patient.⁶ The primary endpoint of laboratory-confirmed clinical influenza was met by 1.9% and 13.6% of participants receiving baloxavir and placebo, respectively (adjusted risk ratio [aRR]=0.14; 95% CI: 0.06-0.30; p<0.001).[mfn referencenumber=6]Ikematsu H et al. N Engl J Med. Published online July 8, 2020.[/mfn] Baloxavir prophylaxis led to a lower percentage of patients with RT-PCR confirmed illness than placebo (aRR=0.24; 95% CI: 0.15-0.38), and a lower percentage of patients with RT-PCR-confirmed influenza virus infection regardless of fever and symptoms (aRR=0.43; 95% CI: 0.32-0.58).⁶

Adverse events (AEs) were reported in 22.2% of participants who received baloxavir, and 20.5% of those who received placebo.⁶ The most common adverse events were headache, haematuria, pharyngitis, and increases in alanine aminotransferase levels.⁶

Reference

Centre for Health Protection, Department of Health – Seasonal Influenza. Available at: https://www.chp.gov.hk/en/healthtopics/content/24/29.html (Accessed 9 December 2020).

O’Hanlon R et al. Curr Opin Virol. 2019;35:14-18.

Drug Office, Department of Health. Available at: https://www.drugoffice.gov.hk/eps/drug/productDetail/en/consumer/122421 (Accessed 9 December 2020).

Roche announces FDA approval of Xofluza for the prevention of influenza following contact with an infected person. Roche. Available at: https://www.roche.com/media/releases/med-cor-2020-11-24.htm (Accessed 9 December 2020).

EMA Panel Backs Xofluza for Influenza, Post-Exposure Prophylaxis. Medscape. Available at: https://www.medscape.com/viewarticle/941059 (Accessed 9 December 2020).

Ikematsu H et al. N Engl J Med. Published online July 8, 2020.

Disclaimer

This article is not medical advice. Patients should seek personal assessment by a licenced specialist. Physicians are recommended to read the full publication(s) as cited in the article before making medical decisions. This article does not supersede nor replace the published article(s).