New Drug Targeting IL-6 Could Mitigate Severity of Covid-19
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Understanding the Severity of Covid-19
One of the most baffling elements of Covid-19 is its unpredictable severity. While some individuals develop severe acute respiratory syndrome (SARS) from the virus, researchers have not yet identified a clear pattern to predict who will experience this severe form of the disease. To address this, scientists are focusing on the human immune system rather than the virus itself, seeking potential targets that might reduce the risk of severe Covid-19 cases. Currently, a clinical trial is exploring an existing medication that targets a cytokine involved in the acute immune response, aiming to prevent the progression of Covid-19 into SARS. However, the question remains: Is it wise to suppress the immune system during an active infection? The results of these trials may uncover critical mechanisms in combating Covid-19.
Clinical Trials for Kevzara
In partnership with Sanofi, Regeneron is conducting clinical trials on Kevzara (sarulimab), a medication designed to inhibit the action of interleukin-6 (IL-6). As an immune-modulating compound, IL-6 plays a significant role in the body's acute response to infections. Kevzara functions as a monoclonal antibody treatment that targets the IL-6 receptor on cells, effectively reducing IL-6 activity. This type of drug is already used to treat acute inflammatory or autoimmune disorders, like rheumatoid arthritis, where it has been shown to mitigate inflammation caused by IL-6 signaling.
The Role of IL-6 in Covid-19
The rapid inflammatory response triggered by the coronavirus, partly mediated by IL-6, is thought to contribute to the decline in lung function associated with SARS. IL-6 belongs to a group of proteins known as cytokines (derived from "cyto" meaning cell and "kine" meaning movement) that cells release as intercellular signals. Once released, cytokines bind to the surface of nearby cells, and upon binding to its receptor, IL-6 induces symptoms typically seen in acute illnesses, such as high fever. During a coronavirus infection in the lungs, the rapid viral replication leads to significant inflammation within the affected tissues.
This intense immune reaction, often referred to as a cytokine storm, is characterized by the sudden surge of cytokines like IL-6, which sends the immune system into overdrive. While this heightened response is aimed at swiftly combating pathogens, it can inadvertently harm surrounding tissues and, in some cases, become life-threatening.
The Mechanism of Kevzara
Kevzara specifically targets the IL-6 receptor rather than IL-6 itself. The antibodies in this medication are engineered to bind to the receptor, preventing IL-6 from attaching and thus halting its acute response. This treatment is intended for individuals suffering from acute Covid-19 and is not meant for preventative use against the virus. Currently, phase II/III clinical trials are enrolling 400 participants with acute Covid-19 to assess the safety and effectiveness of this treatment.
The initial patients outside the US received their first doses of Kevzara on March 30th.
Risks and Considerations
Suppressing the immune system during an active infection carries inherent risks. The role of IL-6 is complex and multifaceted, and our understanding of its function in the context of Covid-19 is still limited. These clinical trials aim to provide insights into any potential adverse effects of this therapeutic approach. Nevertheless, effectively managing the acute immune response to Covid-19 could be essential for reducing the number of severely ill patients. This, in turn, would alleviate the strain on healthcare providers, decrease hospital overcrowding, and potentially lower mortality rates.