Treatment of Severe Infection With Antihyperlipidemia Drug

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection with a high mortality rate. The main causative agents in the ICU to cause sepsis and septic shock are gram negative bacteria Klebsiella spp., Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) and gram positive Staphylococcus aureus (S. aureus), Streptococcus pyogenes (S. pyogenes). The role of bacterial endotoxin is known to be central to development of septic shock in gram-negative bacterial sepsis. Gram negative bacteria's membranes are made of lipopolysaccharides (LPS), the endotoxin. The pattern recognition receptor for LPS is Toll-like receptor 4 (TLR4), upon activation initiates the inflammatory cascade.

In past studies it was demonstrated that despite the lack of LPS on gram positive bacteria, TLR4 mutant's mice had higher bacterial burden and lower survivability suggesting a role in the inflammatory cascade of TLR4 despite the lack of LPS.

Super antigen bind directly to the major histocompatibility complex II (MHC-II) receptor and T cell receptor causing a massive T cell activation bypassing the antigen presenting cell leading to cytokine storm.

Studies on murine, measuring the levels of LDL during inflammation, demonstrated a high level of LDL in the blood due to suppression of LDL receptor proteins in the liver. Proprotein convertase subtilisin kexin 9 (PCSK9) is a serine protease secreted by the liver binding to the LDL receptor and enhancing its degradation causing the increase of LDL levels in the blood. In the absence of PCSK9, the number of LDL receptors on the liver cell surface increases and more circulating LDL is removed from the plasma.

PCSK9 is found to increase during inflammation. Grefhorst A et al, demonstrated that administration of recombinant PCSK9 to mice reduced hepatic LDL receptors. Based on that finding, Kenneth R. Feingold et al, conducted a study administering lipopolysaccharides (LPS) to mice intra peritoneal, measuring the levels of hepatic LDL receptor protein levels, and PCSK9 messenger ribonucleic acid (mRNA) levels in the liver and in the kidneys. There was an increase in the PCSK9 levels within 4 hours in response to LPS and in response to several other mechanisms causing systemic inflammation.

Microbial pathogenic lipids, namely LPS in gram negative bacteria, lipoteichoic acid in gram-positive bacteria, and phospholipomannan in fungi, are bound to lipids in the blood, causing an increase in PCSK9 in plasma. This led to the speculation that increased lipid clearance by the liver leads to increased LPS clearance affecting the process of sepsis and septic shock. Thus administering PCSK9 inhibitor leading to increase in lipids uptake by the liver would positively affect the septic patient.

The benefit of inhibiting PCSK9 in sepsis is further strengthened by a study of Keith R et al examining septic patients who had at least one PCSK9 loss of function allele that showed increased survival over a 28-day period compared to those with gain of function allele.

A study made by, Berger J M et al, on murines showed lack of benefit in septic mice when administering PCSK9 inhibitor adjacent to LPS injection peritoneally. In this study PCSK9 inhibitor was administered as a monotherapy while in studies showing benefit, antibiotics treatment was given. Furthermore the lack of benefit can be explained by the short duration between the induction of endotoxemia to PCSK9 inhibitors administration, inhibiting the binding of the inflammatory mediators to the lipid transports in the blood prior to the activation of the inflammatory response which is needed. As previously mentioned PCSK9 levels that were measured in past studies only increased after 4 hours from inflammatory induction and not immediately after the exposure to LPS.

Due to the results of studies supporting the clinical benefit of PCSK9 inhibitors the investigators intend to conduct a study in septic patients and septic shock patients upon admission to the ICU.

The PCSK9 inhibitor is a relatively safe drug with a small amount of mild adverse events. In the "ODYSSEY LONG TERM" study with 2341 patients, examining among others the safety of the PCSK9 inhibitor use, Alirocumab, at a dose of 150 mg had similar rates of adverse events between the treatment group and the placebo. The Alirocumab patients had higher rates than the placebo group with injection-site reactions, myalgia, neurocognitive events (amnesia, memory impairment, and confusional state), and ophthalmologic events at low rates. In a recent large meta-analysis examining adverse effects showed no statistical significant regarding neurocognitive events or diabetes. Same results were received in a small post marketing study finding most adverse events of flu like symptoms and myalgia without difference between placebo, Alirocumab 75 mg dose and the 150 mg dose.

In order to validate the clinical use of PCSK9 inhibitor the investigators plan to administer 150 mg subcutaneous injection of Alirocumab upon admission to the ICU to patients diagnosed with sepsis or septic shock every two weeks. Two centers will be participating in the study from Israel.