Green light from the Italian Medicines Agency (Aifa) to a combination of two long-acting monoclonal antibodies (tixagevimab and cilgavimab) to prevent Covid-19 in frail patients before exposure to the virus. In the international Phase 3 Provent study of approximately 5,200 people, the mix of Anglo-Swedish AstraZeneca showed a statistically significant reduction, equal to 83%, in the risk of developing the disease in a symptomatic formwith protection that continues for at least 6 months after a single dose.
Covid pre-exposure prophylaxis – a note recalls – is a particularly important weapon to protect the most vulnerable, such as people with chronic lymphocytic leukemia, primary or acquired immunodeficiencies or those undergoing immunosuppressive treatments such as transplant recipients. The one authorized is the only pharmacological option based on antibodies authorized for emergency use also in Italy for coronavirus pre-exposure prophylaxis pandemic.
“A monoclonal antibody – explains Giovanni Di Perri, director of the School of Specialization in Infectious Diseases of the University of Turin and head of the University Division of Infectious Diseases at the Amedeo di Savoia Hospital – is a type of protein designed to recognize and bind to a a specific structure, called an antigen. Tixagevimab and cilgavimab have been developed to bind to two distinct sites on the Spike protein of Sars-CoV-2. The combination prevents the virus from entering the body’s cells and causing infection. Because the two antibodies they attach to different parts of the protein, their use in combination may be more effective. The available phase 3 data also demonstrate long-term protection in the population at high risk of contracting Covid, even with a single dose. Recent evidence indicates that protecting vulnerable people helps prevent viral evolution, which is an important factor in compar he knows about variants “.
Following the AIFA assessments, the Ministry of Health, on January 28th, granted the authorization for the emergency use for the combination of the two antibodies for pre-exposure prophylaxis to Covid-19 in adults and adolescents (of 12 years of age and older) with moderate to severe immune impairment due to a medical condition or immunosuppressive drugs and who may not develop an adequate immune response to Covid vaccination, and for people for whom immunization is not recommended . Recipients must not be infected or have had recent known exposure with a person infected with Sars-CoV-2.
“Since the beginning of the pandemic – says Raffaela Fede, medical director of AstraZeneca Italy – AstraZeneca’s research has been at the forefront to protect citizens against Covid-19, starting with the vaccine which remains the main defense. The combination of tixagevimab and cilgavimab represents an additional protection that is therefore added to that of vaccines to protect the most fragile people. The two antibodies, derived from B cells donated by convalescent patients after Sars-CoV-2, were identified by experts at Vanderbilt University Medical Center in the United States. The combination was optimized using AstraZeneca’s half-life extension technology, which tripled its duration of action compared to conventional monoclonals. More follow-up is needed to establish the full duration of virus protection, but we could estimate it beyond 12 months after a single administration consisting of two intramuscular injections, one for each antibody, separate and consecutive, in immediate succession“.
There combination of antibodies maintains efficacy in neutralizing hitherto known variants, including Omicronaccording to data from three independent studies conducted by the University College of Oxford (United Kingdom), the Washington University School of Medicine in St. Louis (USA) and the FDA (Food and Drug Administration).
“The neutralization capacity of the combination – underlines Di Perri – falls within the range of neutralizing antibody levels found in individuals infected with Covid-19 and naturally cured. The data of the three independent studies agree in demonstrating that the combination of these two antibodies a high concentration and characterized by different binding sites maintains a neutralizing activity against the Omicron variant at a level that continues to provide benefits. This weapon can therefore integrate the vaccination path of the most fragile “.
Tixagevimab plus cilgavimab is also being tested as a potential treatment for patients already affected by Covid-19. In fact, the phase 3 Tackle study reached the primary endpoint, demonstrating to reduce the risk of mild-moderate to severe disease progression or death compared to placebo in non-hospitalized patients with symptomatic Covid for a period equal to or less than 7 days.
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