Presentation on theme: "Jennifer G. Robinson, MD, MPH, Program Chair President, Midwest Lipid Association Associate Professor Departments of Epidemiology and Medicine Director,"— Presentation transcript:
Jennifer G. Robinson, MD, MPH, Program Chair President, Midwest Lipid Association Associate Professor Departments of Epidemiology and Medicine Director, Lipid Research Clinic University of Iowa Iowa City, IA “An Examination of the ENHANCE Trial”
Kastelein JJP, et al. N Engl J Med 2008;358:
ENHANCE Study Design Simvastatin 80 mg RANDOMIZATIONRANDOMIZATION 0 24 Months Pre-randomization Phase FH: LDL-c ≥ 210 mg/dL Screening and Fibrate Washout Placebo Lead- In/ Drug Washout Weeks to -7 Ezetimibe 10 mg-Simvastatin 80 mg IMT assessment
ENHANCE Baseline Characteristics Simvastatin Monotherapy Simvastatin plus Ezetimibe All randomized patientsn=363n=357P-value Age (yr) 45.7 Male sex no. (%)179(49%)191 (54%)0.26 Body-mass index 26.7 History of diabetes5(1%)8 (2%)0.38 Hypertension51 (14%)67 (19%)0.09 Current smoking104 (29%)102 (29%)0.98 History of MI26 (7%)14 (4%)0.06 Prior use of statins297 (82%)286 (80%)0.56 Systolic mm Hg 124 Diastolic mm Hg 78 1078
Primary outcome Change from baseline in mean CIMT – Average of means of the far-wall IMT of R & L carotid arteries, carotid bulbs, & internal carotid arteries ENHANCE
Variable Simvastatin 80 mg Simvastatin 80 mg + Ezetimibe 10 mg P value (mean) MeanMedianMeanMedian Millimeters Baselinen=342n=338 Mean cIMT 0.70 Mean maximum cIMT 0.80 months follow-upn=320n=322 Mean cIMT 0.70 Mean maximum cIMT0.81± ± Difference baseline to 24 months Mean cIMT Mean maximum cIMT No significant changes in 1° or 2° endpoints - Consistent inferential results observed for non-parametric (median) and parametric (mean) analyses - Exclusion of patients with missing data or biologically implausible measures did not change primary or secondary outcomes
Mean cIMT during 24 months of therapy Longitudinal, repeated measures analysis ENHANCE Mean IMT (mm) Simva Eze-Simva Months P=0.88
ENHANCE Safety Simva 80 mgSimva 80/Eze 10 mg p Consecutiven=360n=356 ALT and/or AST ≥ 3 X ULN CPK ≥ 10 X ULN Both regimens well tolerated, with overall safety profiles generally similar and consistent with product labels One case of viral hepatitis A in the simvastatin-only arm One case of myopathy (defined as CPK > 10 ULN, with associated muscle symptoms) in the simvastatin-only arm and 2 cases in the Ezetimibe- Simvastatin arm Subjects with 2 consecutive measurements for ALT and/or AST; a single last measurement ≥ 3 ULN; a measurement ≥ 3 X ULN followed by < 2 ULN that was taken more than 2 days after the last dose of study medication
Evan A. Stein, MD, PhD Director, Metabolic and Atherosclerosis Research Center Voluntary Professor of Pathology and Laboratory Medicine University of Cincinnati Cincinnati, OH “An Examination of the ENHANCE Trial”
Questions after ENHANCE Why were the results of ENHANCE different from the earlier carotid IMT trials?
The Trial Design and Population To have any chance using cIMT of demonstrating that one treatment is better than another two critical factors must be present: The population studied must have significant and quantifiable lipid rich intima – if minimal or no significant atherosclerosis is present then only possible change to be assessed is progression The ‘control’ group must show significant progression – if not then only significant regression in the ‘test’ group can result in a positive trial
Critical Factors for Successful cIMT Trial progression regression
Critical Factors for Successful cIMT Trial regression progression regression progression cIMT mm years ASAP ASAP Simva LDLc -40% Atorva LDLc -52% In ASAP the patient population had cIMT with mean baseline of 0.92 mm indicating presence of lipid enriched atherosclerosis In ASAP the ‘control’ group of simvastatin showed significant progression of mm/2yrs despite 40% reduction in LDLc Simva progressed; atorva regressed = SUCCESS!! P <0.05
Critical Factors for Successful cIMT Trial regression progression regression progression cIMT mm years ASAP ENHANCE ENHANCE Simva LDLc -40% Simva/Eze LDLc -57% ASAP Simva LDLc -40% Atorva LDLc -52% P= ns Simva No progress; Sim/Eze No regress FAILURE!!
Critical Factors for Successful cIMT Trial ASAP Simva LDLc -40% Atorva LDLc -52% Identical FH populations 25% less cIMT REGRESSION!!! ENHANCE Simva LDLc -40% Simva/Eze LDLc -57% regression progression cIMT mm years ASAP ENHANCE
The Patient Population What changed from ASAP to ENHANCE? In ASAP, the study upon which ENHANCE was based, the progression in cIMT over 2 years in the simvastatin 40 mg treated group (LDLc decrease 40%) was mm over 2 years. At the end of the 2 year ENHANCE trial the change in cIMT was substantially less than projected in both groups at mm in the Eze/Simva group and mm in the simvastatin 80 mg group (p=0.29 NS). Thus a 40% reduction in LDLc both trials, done 5 years apart, with the same drug, in the same patient population and similar entry LDLc levels resulted in 6 fold less progression of cIMT in ENHANCE The only difference in the simvastatin monotherapy groups between the two studies was the pre-treatment of patients and the amount of baseline atherosclerosis in ENHANCE. ASAP was recruited in 1997 in Holland from a large screening program for FH, only few statins (prava, simva, fluva) available in prior years and not aggressive Rx ENHANCE recruited from global well established lipid clinics with large and long identified and aggressively Rx patients
ENHANCE The Population Thus in ENHANCE neither of the two critical factors needed for any chance of a positive outcome, for ezetimibe, or likely any other treatment, existed! The population studied did not have significant and quantifiable lipid rich intima – the majority would not even have qualified for any other IMT trial such as METEOR The ‘control’ group did not show significant progression – in fact the same treatment as in ASAP resulted in no progression over 2 years The most obvious and scientific explanation of ENHANCE results is that it was a failed trial and not a failed drug. If one were to test an antibiotic it is crucial to recruit patients with an infection, if not then no matter how good the antibiotic it will be impossible to show it is better than even placebo!
The Patient Population What about the subgroup with ‘thick’ baseline cIMT? In neither the patients in the highest quintile or those above the median was there any difference – does this invalidate the argument that the population had too little atherosclerosis? As there was no compositional studies of the intimal wall, only measurement of thickness, it is entirely possible, if not likely, that the amount of lipid within the wall even in these patients was minimal after many years of prior lipid lowering therapy and the thicker intima was due to non-lipid, more fibrous tissue, making it resistant to ‘regression’ The data from the pre-specified analysis but using medians in the small number of subjects (20% of total) who had not received lipid lowering therapy prior to the trial, provides support for this as presumably their more lipid enriched intima showed a separation between the treatment groups in favor of more intense lipid and hs-CRP reduction.
No significant changes in those with no prior statin Rx using means Change cIMT (mm) ENHANCE Progression Regression
Subgroup Analysis – IMT Change by Reported Statin Pretreatment: medians Median change in Mean cIMT (mm) Pre Statin-High (n=112/115) Pre Statin-Low (n=149/143) No Statin (n=59/64) Median Change for Patients Reporting No Statin Use at Baseline Median 25 th, 75 th percentiles Simva , EZ/Simva 10/ , Simva 80 EZ Simva 10/80
ENHANCE What about the trial indicating potential harm from increased CVD events? Although ENHANCE was a relatively small trial in low risk FH patients was there any evidence from the CVD events that addition of ezetimibe caused harm? Can one even pick up such a signal from such small trials as ENHANCE in this FH population?
CVD Events – recent FH cIMT trials: Can these small trials give some hint of CVD harm? *RADIANCE I (CETPi) and **CAPTIVATE (ACATi) Incidence of CVD events (%)AtorvastatinAtorva + TorcetStatin+Statin+ ACATi (n=454)(n=450)(n=438)(n=443) CVD death/MI/ Revasc/Stroke11 (2.4%)23 (5.1%)`15 (3.4%)28 (6.3%)` RADIANCE I *Kastelein et al NEJM 2007; 356: **Meuwese MC et al AHA New Orleans 2007 (in press) CAPTIVATE `p<0.05 Thus even small studies ( patients) in FH appear to be able to detect potential CVD harm
The Compound Ezetimibe lowers LDLc by a different mechanism than statins? ENHANCE Reflects total ignorance of lipid physiology as the mechanism by which LDLc is reduced is in fact identical whether treated with statin (HMG CoA reductase inhibition), cholesterol absorption inhibition or bile acid sequestration! In all three modalities there is a depletion of hepatic intracellular cholesterol and the cell responds by upregulation of the LDL receptor – doubtful if the carotid arterial wall can detect the mechanism by which receptor upregulation occurred!! LDLc reduction by other mechanisms, such as fibrates, niacin, MTP inhibition, Apo B antisense or CETP inhibition is different as none involve the LDL receptor.
The Compound Ezetimibe lowers LDLc by a different mechanism than statins? Hepatic cellular lipid regulation X CATI (eze) Cholesterol [ ] HMG-CoA Acetoacetyl-CoA Mevalonic acid Squalene Lanosterol Statins X X Bile BAS LDL LDL-R
The Compound Ezetimibe no pleiotropic effects? ENHANCE Pleotrophic effects are manifest through an impact on vascular inflammation and the ‘best’ biomarker for inflammation and thus pleotrophism is accepted as hs-CRP In ENHANCE hs-CRP was reduced very robustly, in fact 50% more than the added LDLc reduction in the Eze/Simva group than simvastatin alone Effect on other apo B containing lipoproteins were robust and on HDLc was significantly (p=0.05) increased by addition of ezetimibe
Conclusion The addition of Ezetimibe to Simvastatin did lead to expected changes in LDL-c and hsCRP, but did not reduce any cIMT parameter more than simvastatin alone The most likely reason is that the patient population had minimal lipid in their carotid arteries and thus inability to show any change no matter how much better the treatment of one group was compared to the other There were no safety differences between the groups and no significant differences in cardiovascular events ENHANCE
Conclusion The most obvious and scientific explanation of ENHANCE results is that it was a failed trial and not a failed drug. While the results of ENHANCE have been less than optimal for the sponsors of the trial they actually carry very good news for those with FH, and all patients on long term lipid lowering therapy, in that the data would seem to strongly indicate that even moderate, long term LDLc lowering dramatically reduces the atherosclerotic burden, at least in carotid arteries, and virtually halts progression of the underlying disease. Thus the glass is not half empty but clearly more than half full! ENHANCE
“An Examination of the ENHANCE Trial” Michael H. Davidson, MD, FACC, FACP Clinical Professor Director, Preventive Cardiology The University of Chicago Executive Medical Director Radiant Research Chicago, IL
Questions after ENHANCE Is there reason to suspect that ezetimibe’s mechanism of action is less effective than that of statins?
“An Examination of the ENHANCE Trial” B. Greg Brown, MD, PhD Professor of Medicine and Cardiology University of Washington School of Medicine Seattle, WA
Questions after ENHANCE Can the ENHANCE results be interpreted in any way other than: “Ezetimibe is just an expensive placebo”?
Comparisons of Carotid Plaque Tissue Composition: Two Groups of Eight Matched Patients Triple Therapy x 10 years Untreated 2 Fibrous tissue area, mm 2 (% of total plaque) Lipid plus calcium area, mm 2 (% of total plaque) Lipid deposits area, mm 2 (% of total plaque) Calcium cluster area, mm 2 (% of total plaque) 46 mm 2 (84%) 49 mm 2 (77%) 5 mm 2 (5%) 3 mm 2 (3%) 2 mm 2 (3%) 6 mm 2 (10%) 0.7 mm 2 (1%)* 10.2 mm 2 (17%)* Total plaque area = 58 mm 2 Total plaque area = 64 mm 2 *p=0.01 Zhao, X-Q, et al. ATVB 2001;21:
Jennifer G. Robinson, MD, MPH Associate Professor Departments of Epidemiology and Medicine Director, Lipid Research Clinic University of Iowa Iowa City, IA “An Examination of the ENHANCE Trial”
Questions after ENHANCE Is there evidence to support the use of alternative LDL-lowering therapies?
CHD + Diabetes Selection of patients for more aggressive LDL- lowering: Risk curve concept Robinson JG, Stone NJ. Am J Cardiol 2006: 98:
Add-on to statin therapy Drug options to ↓LDL & ↓Non-HDL-C DrugLDL-CNon-HDL-CTrigsHDL-C Double statin dose-6% -2 to -12%-2 to +2% Ezetimibe 10 mg-15%-12%-9%NS Niacin 2 gr-14%-31%*-24%+18% Bile acid binding agent Colestipol 2 scoops (6 gr) Cholestyramine 2 scoops (8 gr) Coleselvalam 6 tabs (3.75 gr) -12%-5-8%0 to +23%+1-7% Fenofibrate 145 mg-6% to +4%-3% to -18%*-15 to -20%+13% Gemfibrozil 600 mg BID+7%+2%-18%0% Jones PH, et al. Am J Cardiol 2003; 92: Robinson JG, Davidson MH. Expert Rev Cardiovasc Ther. 2006: 4: Kos Niaspan® prescribing information 2005 Sankyo Welchol® prescribing information 2005 Athyros VG et al. Diabetes Care 2002; 25: ; Durrington PN et al. Diab Res Clin Pract 2004; 64: Wagner AM, et al. J Clin Endocrinol Metab 2003; 88: *Estimated Total cholesterol-HDL
Consistent relationship between LDL-C reduction and CHD relative risk for all LDL- lowering treatments Robinson JG et al. J Am Coll Cardiol. 2005;46:1855– – LDL-C reduction, % Nonfatal MI and CHD death relative risk reduction, % 4SCARDS POSCHASCOT-LLA NHLBI PROSPER LRC ALERT UpjohnHPS Los Angeles AF/TexCAPS MRC LIPID OsloCARE LondonWOSCOPS Cholestyramine Colestipol
Niacin RCTs Unpublished
PPAR agonists: Expected CVD risk reduction from LDL & HDL changes Robinson JG. PPAR Review 2008; in press
Gemfibrozil vs Fenofibrate Adverse Events (excluding reports with concomitant cerivastatin use) submitted to the US Food and Drug Administration from January 2000 to December 2004 Adverse Event Reports GemfibrozilFenofibrate Gemfib vs Feno OR 95% CI P-value Rates/million prescriptions Gemfibrozil better All – 0.83<0.001 Serious – 0.81<0.001 Liver – 0.50<0.001 Fenofibrate better Rhabdomyolysis – 3.39<0.001 Muscle-related with no rhabdomyolysis – Holoshitz N, et al. Am J Cardiol 2008; 101: 95-97
“An Examination of the ENHANCE Trial” Hosted by the Midwest Lipid Association Jerome Cohen, MD, FACC, FAHA, FACP Chair, NLA Consumer Affairs Committee Professor Emeritus St. Louis University School of Medicine St. Louis, MO
Questions after ENHANCE How should ezetimibe continue to be used in clinical practice?