PCSK9 inhibitors may best be known for their powerful LDL-lowering effects but are less appreciated as anti-inflammatory agents with potential beyond cardiovascular health.
In a small pilot trial, for example, patients hospitalized with severe COVID-19 who received a single injection of PCSK9 inhibitor became less sick and more likely to survive than those given a placebo. Their 30-day risk of death or intubation fell significantly, as did their levels of the inflammatory cytokine interleukin 6 (IL-6).
Indeed, survival gains in the PCSK9-inhibitor group were greatest among patients with higher baseline concentrations of IL-6. Although the trial wasn’t powered for clinical outcomes, it suggests the drugs’ efficacy in COVID-19 tracks with intensity of inflammation, proposes a report published in the Journal of the American College of Cardiology.
Therefore, “PCSK9 inhibition may represent a novel therapeutic pathway in addition to currently recommended therapeutic approaches for severe COVID-19,” conclude the authors, led by Eliano P. Navarese, MD, PhD, Nicolaus Copernicus University, Bydgoszcz, Poland.
PCSK9 inhibitors as anti-inflammatories
Although the study was small and only hypothesis-generating, the fact that outcomes for actively treated patients were proportional to baseline IL-6 levels “strongly suggests that PCSK9 inhibition can directly modulate inflammation in COVID-19,” argues an editorial accompanying the report.
and likely sheds light on “mechanisms through which PCSK9 inhibition dually modulates lipoprotein metabolism and inflammation,” write Sascha N. Goonewardena, MD, University of Michigan, Ann Arbor, and Robert S. Rosenson, MD, Icahn School of Medicine at Mount Sinai, New York.
The results are consistent with prior evidence that the drugs are anti-inflammatory at least partly because of their interference with inflammatory pathways triggered by PCSK9 and mediated by IL-6, as described by Dr. Navarese and colleagues.
Indeed, they write, PCSK9 inhibitors may improve COVID outcomes mostly through mechanisms unrelated to LDL-receptor expression, “including direct inhibition of PCSK9-triggered inflammation.”
If true, the authors observe, it might explain “why the positive findings of the present study have not been consistently observed in trials involving other lipid-lowering agents, such as statins.” Those drugs are well-known to decrease levels of the inflammatory biomarker C-reactive protein.
In patients with stable coronary disease, in whom inflammation is typically tracked by measuring CRP, “the PCSK9 inhibitors have not been shown to have an anti-inflammatory effect,” Dr. Rosenson further explained.
But the current study’s patients with acute, severe COVID-19, a “profound inflammatory insult” with upregulation of IL-6, were “a good population” for evaluating the drugs’ potential anti-inflammatory effects, Dr. Rosenson said in an interview. The results “are quite enticing but require corroboration in a larger trial.”
A single injection
The IMPACT-SIRIO 5 trial entered 60 adults hospitalized with severe COVID-19 and elevated IL-6 at four centers in Poland. Patients with other known active infections were excluded.
They were randomly assigned double-blind to receive a 140 mg injection of evolocumab (Repatha) or placebo. The 2 groups were similar with respect to demographics, body-mass index, time since symptom onset, and treatments for managing COVID-19 and its complications.
Rates of death or need for intubation at 30 days, the primary endpoint, were 23.3% in the PCSK9-inhibitor group and 53.3% for controls, a risk difference of 30% (95% confidence interval –53.4% to –6.6%). The median durations of oxygen therapy were significantly different at 13 days and 20 days, respectively, the report states.
Serum IL-6 levels fell further over 30 days in the PCSK9-inhibitor group (–56% vs. –21% among controls). A drop by more than 90% was seen in 60% of patients in the PCSK9-inhibitor group and in 27% of controls.
The average hospital stay was shorter for those getting the PCSK9 inhibitor, compared with placebo, 16 days versus 22 days, and their 30-day mortality was numerically lower, 16% versus 33.3%.
Patients’ baseline IL-6 levels above the median, the report states, had a lower mortality on the PCSK9 inhibitor versus placebo (risk difference –37.5%; 95% CI –68.2% to –6.70%).
A larger trial to corroborate these results would potentially enter similar patients hospitalized with COVID-19 with reproducible evidence of an ongoing cytokine storm, such as elevated levels of IL-6, who would be assigned to either a PCSK9 inhibitor or placebo, Dr. Rosenson proposed.
Although the current primary endpoint that combines mortality and intubation was “reasonable” for a small pilot trial, he said, if the researchers embark on a larger study, “they’ll want to look at those events separately.”
Dr. Navarese discloses receiving speaker and consultancy fees from Amgen, Sanofi-Regeneron, Bayer; and grants from Abbott. Disclosures for the other authors are in the report. Rosenson discloses receiving research funding to his institution from Amgen, Arrowhead, Eli Lilly, Novartis, and Regeneron; consulting fees from Amgen, Arrowhead, CRISPR Therapeutics, Eli Lilly, Lipigon, Novartis, Precision Biosciences, Regeneron, Ultragenyx, and Verve; speaking fees from Amgen, Kowa, and Regeneron; and royalties from Wolters Kluwer; and owning stock in MediMergent. Dr. Goonewardena reports no relevant financial relationships.
A version of this article first appeared on Medscape.com.