Stratification biomarker for anti-PCSK9 therapy

Summary: An assay to identify ‘responders vs non-responders’ to anti-PCSK9 therapy.

Technology Overview

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that regulates circulating low-density lipoprotein cholesterol (LDL-C) through the hepatic LDL receptor degradation pathway. It is a known therapeutic target to further lower LDL-C in patients suffering from dyslipidemia/hypercholesterolemia and who are already on maximal statin therapy. Currently there are several anti-PCSK9 therapies either in development or on the market. However, potent LDL lowering effects of anti-PCSK9 therapies in patients are not always as expected.

Circulating PCSK9 is known to exist in a free and bound form in the circulation, and in particular has been shown to bind LDL and lipoprotein(a) (Lp(a)). The association of circulating PCSK9 with lipoproteins is expected to impact on the capacity of PCSK9 to degrade the LDL receptor.

Prof Mayr and his team’s recent findings have shown for the very first time that PCSK9 is predominantly associated with high-density lipoprotein (HDL) in human plasma.  Their findings that PCSK9 can bind multiple lipoprotein classes, show that PCSK9-lipoprotein compartmentalisation could be an underappreciated regulator of its biological activity and susceptibility to therapy by anti- PCSK9 therapies.

The team has developed a method of assessing unbound PCSK9 in a subject based on their novel findings. Specifically, depleting lipoproteins from a sample allows assessment of the level of ‘free’ vs lipoprotein bound PCSK9 by ELISA.  Patients that may have more “free” PCSK9 may be the ones that benefit the most from PCSK9 inhibition therapy than the ones whose PCSK9 is mostly bound.  PCSK9-lipoprotein interactions are expected to alter activity and therapeutic targeting.

The Science

King’s team has investigated PCSK9-lipoprotein association using nuclear magnetic resonance (NMR)-based lipoprotein profiling, quantitative multiplexed proteomics and targeted lipidomics in the setting of cardiovascular disease (CVD) and postprandial lipaemia.

In a large collection of HDL samples (n=170, unpublished data) from patients with CVD, they assessed the impact of PCSK9 on the protein and lipid composition of HDL across multiple CVD phenotypes and gained novel insights into HDL remodelling during postprandial hyperlipaemia, with PCSK9 dynamics emerging as a central feature. The potential associations of PCSK9 with different human lipoproteins was first determined by immuno-capture   in 20 healthy volunteers.  Measurement of lipoprotein-associated PCSK9 suggested a predominant association of PCSK9 with HDL (Figure 1). King’s team has produced 5 lines of evidence to support its conclusion: immuno-capture of PCSK9-associated lipoproteins, plasma PCSK9 concentrations after ApoB and after HDL depletion, and enrichment of PCSK9 on HDL after immuno isolation from plasma and from an ApoB-depleted OptiPrepTM fraction.


Figure 1. PCSK9 is primarily associated with HDL in the human circulation. (A) Lipoprotein-associated PCSK9 was determined through the use of a modified enzyme-linked immunosorbent assay (n=20, healthy volunteers). (B) HDL was immuno-isolated from human plasma and non-depleted plasma, HDL-depleted plasma and HDL fraction were subjected to immunoblotting to determine PCSK9 and apolipoprotein-A1 (ApoA1) enrichment; these findings were replicated using fasted plasma separated by OptiPrepTM gradients, whereby HDL was immuno-isolated from the Apolipoprotein-B depleted, “heavy” fraction. Apo(a) = apolipoprotein(a).   


  • Determination of ‘free’ vs ‘lipoprotein-bound’ PCSK9 could lead to identification of subjects most likely to benefit from anti-PCSK9 therapy.
  • Beneficial in monitoring the progress and response to therapy in a subject.
  • Selecting a dosage regimen for treating a subject with an inhibitor or putative inhibitor of PCSK9
  • Potential utility in clinical trials which are based on targeting PCSK9, for example by selection of specific patient groups or dosage regimens.

Development Status

Further refinement and validation of these findings in larger patient samples currently on anti-PCK9 therapy is ongoing.


King’s is now seeking a collaboration and development partner to further develop this technology.

Further detailed information including unpublished data from a cohort of 170 CVD patients is available on request.

Patent Information:
For Information, Contact:
Salma Ishaq
IP & Licensing Manager
King's College London
Manuel Mayr
Sean Burnap