An observational study found that people with COVID-19 who received these drugs early fared better than those who received them after they became critically ill. The study also suggests that the inhibitors may be more effective than remdesivir or dexamethasone.
The immune systems of people with severe COVID-19 can go into overdrive, causing excessive inflammation that worsens their breathing difficulties.
This “cytokine release syndrome,” or “cytokine storm,” can lead to potentially fatal respiratory distress syndrome.
During the pandemic, healthcare professionals have been using immune-modifying drugs called interleukin-6 (IL-6) receptor inhibitors “off label” in an attempt to prevent this from happening.
These drugs, which are monoclonal antibodies, work by targeting receptors for an immune signaling molecule, or cytokine, called IL-6. This dampens the excessive immune response.
Healthcare professionals usually prescribe these drugs for rheumatoid arthritis, which is an autoimmune condition in which the immune system attacks the joints.
An earlier observational study, by researchers at the University of Michigan in Ann Arbor, found that an IL-6 receptor inhibitor called tocilizumab improved the survival of COVID-19 patients on ventilators.
Other observational studies have also shown benefits, but the optimal timing for giving IL-6 receptor inhibitors remained unclear.
If a patient receives the drug too early, it may impair the body’s antiviral response. If they receive it too late, after the cytokine-mediated immune response has started to damage tissues, it may be ineffective.
The new study, which took place at Boston Medical Center in Massachusetts, divided 255 patients into two groups according to their need for supplementary oxygen.
One group comprised 106 patients who were critically ill but had not yet undergone intubation, while the other group comprised 149 patients who were at an earlier stage of the disease.
All the patients received tocilizumab or another IL-6 receptor inhibitor called sarilumab.
Over the study period, those who received treatment at the earlier stage of the disease were less likely to die, less likely to require intubation, and more likely to be discharged from the hospital.
There were no significant differences between the groups in terms of preexisting risk factors that are known to worsen outcomes in COVID-19. These include age, coronary artery disease, and high blood pressure.
Of the 255 patients, 34 (13.3%) developed bacterial infections after receiving the drugs. However, these infections were not associated with an increased risk of mortality, the researchers point out.
Dr. Pranay Sinha, who led the study, explains that it showed that patients who received IL-6 receptor inhibitors at an earlier stage of the disease — before critical respiratory decompensation — fared better. This highlights the importance of prompt testing and treatment, he says.
“We hope these findings can help guide physicians as we seek solutions to reduce mortality, increase extubation, reduce length of stay in the hospital, and have more patients discharged from the hospital alive,” he adds.
The results appear in the International Journal of Infectious Diseases.
The researchers note that the overall mortality rate among the study participants, who were all severely ill, was 10.9%. This is comparable with the overall mortality rate of 9.7% to 10.8% for all confirmed cases of COVID-19 in New York City, including both mild and severe infections.
Their analysis also suggests a lower mortality rate with IL-6 receptor inhibitors compared with trials of remdesivir and dexamethasone. These are the only two treatments currently approved for COVID-19.
This was despite patients in the Boston Medical Center study being at more advanced stages of the disease, the researchers add.
The authors acknowledge that their study had several limitations, including its lack of a control group, its lack of randomization, the small size of the cohort, and the missing data, given the pragmatic design.
However, they write that the effectiveness and safety results provide a useful guide for healthcare professionals pending results from larger clinical trials.
“Our finding that prompt [IL-6 receptor inhibitor] treatment prior to the onset of critical disease is associated with reduced mortality from severe COVID-19 disease can be used to guide current clinical management while the medical community awaits more definitive results from randomized controlled trials.”
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