Amgen Drug Evolocumab Hits Endpoint of Cholesterol Reduction

Evolocumab^[1] is a monoclonal antibody designed for the treatment of hyperlipidemia.^[2] Evolocumab is a fully human monoclonal antibody that inhibits proprotein convertase subtilisin/kexin type 9 (PCSK9).

PCSK9 is a protein that targets LDL receptors for degradation and thereby reduces the liver’s ability to remove LDL-C, or “bad” cholesterol, from the blood.

Evolocumab, being developed by Amgen scientists, is designed to bind to PCSK9 and inhibit PCSK9 from binding to LDL receptors on the liver surface. In the absence of PCSK9, there are more LDL receptors on the surface of the liver to remove LDL-C from binding to LDL receptors on the liver surface. In the absence of PCSK9, there are more LDL receptors on the surface of the liver to remove LDL-C from the blood.

On 23 January 2014 Amgen announced that the Phase 3 GAUSS-2 (Goal Achievement After Utilizing an Anti-PCSK9 Antibody in Statin Intolerant Subjects-2) trial evaluating evolocumab in patients with high cholesterol who cannot tolerate statins met its co-primary endpoints: the percent reduction from baseline in low-density lipoprotein cholesterol (LDL-C) at week 12 and the mean percent reduction from baseline in LDL-C at weeks 10 and 12. The mean percent reductions in LDL-C, or “bad” cholesterol, compared to ezetimibe were consistent with results observed in the Phase 2 GAUSS study.^[3]

The GAUSS-2 trial evaluated safety, tolerability and efficacy of evolocumab in 307 patients with high cholesterol who could not tolerate effective doses of at least two different statins due to muscle-related side effects. Patients were randomized to one of four treatment groups: subcutaneous evolocumab 140 mg every two weeks and oral placebo daily; subcutaneous evolocumab 420 mg monthly and oral placebo daily; subcutaneous placebo every two weeks and oral ezetimibe 10 mg daily; or subcutaneous placebo monthly and oral ezetimibe 10 mg daily.

Safety was generally balanced across treatment groups. The most common adverse events (> 5 percent in evolocumab combined group) were headache (7.8 percent evolocumab; 8.8 percent ezetimibe), myalgia (7.8 percent evolocumab; 17.6 percent ezetimibe), pain in extremity (6.8 percent evolocumab; 1.0 percent ezetimibe), and muscle spasms (6.3 percent evolocumab; 3.9 percent ezetimibe).

Evolocumab, a PCSK9 inhibitor, was safe and effective at lowering low-density lipoprotein cholesterol (LDL-C) after one year of treatment, according to a study published online Nov. 19 inCirculation and presented simultaneously at the American Heart Association scientific session in Dallas.

The Open-Label Study of Long-term Evaluation Against LDL-C (OSLER) trial took place at 156 study centers around the world that participated in at least one of four phase 2 studies of between October 2011 and June 2012. Evolocumab is a PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitor made by Amgen.

Investigators led by Michael J. Koren, MD, of the Jacksonville Center for Clinical Research in Florida, randomized 1,104 participants in a 2:1 ratio to receive either evolocumab (420 mg every four weeks) plus standard-of-care therapy (based on guidelines for treatment of hypercholesterolemia) or evolocumab alone, which served as the control. After 12 weeks, lipid results were unblinded and investigators were able to adjust standard-of-care therapy in either group.

The main efficacy objective was to determine the effects of longer-term evolocumab therapy on cholesterol levels and the main safety endpoints included incidence of adverse events, serious adverse events and adverse events resulting in discontinuation of the drug.

Patients who received evolocumab for the first time in the OSLER study had an average LDL-C reduction of 52.3 percent at one year. Patients previously dosed with evolocumab in a prior trial and were in the evolocumab and standard-of-care group in OSLER had an average LDL-C reduction of 52.1 percent at the end of the study compared with 50.4 percent at baseline. Patients who terminated evolocumab when they entered OSLER had their LDL-C levels returned to around their baseline.

Adverse events occurred in 73.1 percent of the standard-of-care group and 81.4 percent of the evolocumab plus standard-of-care group. The researchers determined that 5.6 percent of adverse events were related to evolocumab. Serious adverse events occurred in 6.3 percent of the control group and 7.1 percent in the combination group.

The authors explained that their findings offer more insight into the use of this class of drugs to lower LDL-C in at-risk patients.

“Challenging patients such as those who fail to reach current lipid goals despite maximum doses of highly effective statin agents or those with well-documented statin intolerance are thus logical populations for treatment with PCSK9 inhibitors,” they concluded.

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