Assessing the Potential Risk of Cross-Reactivity Between Anti-Bococizumab Antibodies and Other Anti-PCSK9 Monoclonal Antibodies.

BACKGROUND: Anti-drug antibodies (ADAs) to bococizumab were detected in > 40% of subjects in the SPIRE lipid-lowering trials. The risk of cross-reactivity between anti-bococizumab antibodies and other approved anti-proprotein convertase subtilisin/kexin type-9 (PCSK9) monoclonal antibodies (mAbs) was investigated using a single-assay approach. METHODS: Bococizumab immunogenicity was assessed in SPIRE-HR, a 52-week study. The highest ADA titer sample from each ADA-positive subject (n = 155) was tested in vitro for cross-reactivity to alirocumab and evolocumab using a novel ADA assay approach. Additional specificity tiers within the bococizumab ADA assay against each drug were validated using recombinant PCSK9 as a surrogate cross-reactive positive control. If the highest ADA titer sample showed cross-reactivity, additional samples from that subject were analyzed. Cross-reactivity was determined by the ability of alirocumab or evolocumab to inhibit the sample signal greater than or equal to the cross-reactivity cut-points. RESULTS: ADAs were detected in 44.0% (155/352) of bococizumab-treated subjects, and 27.0% also developed neutralizing antibodies (NAbs). Median ADA and NAb titers ranged from 276 to 526 and 8 to 12 over the course of the study, respectively. From 155 ADA-positive subjects tested for cross-reactivity, one (0.6%) subject showed weak cross-reactivity to both alirocumab and evolocumab. This cross-reactivity signal was transient (from Days 337 to 373) and undetectable at the last ADA-positive timepoint (Day 407). CONCLUSION: A novel, single-assay approach was validated to assess the potential cross-reactivity of anti-bococizumab antibodies to alirocumab and evolocumab. In subjects who developed ADAs to bococizumab, the likelihood of clinically relevant cross-reactivity to marketed anti-PCSK9 mAbs is remote, based on the low frequency of cross-reactivity observed, which was weak in signal inhibition and transient in nature. CLINICAL TRIAL REGISTRATION: The SPIRE-HR study is registered on ClinicalTrials.gov under the identifier NCT01968954.

Cardiovascular event reduction with PCSK9 inhibition among 1578 patients with familial hypercholesterolemia: Results from the SPIRE randomized trials of bococizumab.

BACKGROUND: Familial hypercholesterolemia (FH) is a dominant genetic disorder associated with elevated low-density lipoprotein cholesterol (LDL-C) and premature atherosclerotic events. Although therapeutic monoclonal antibodies that inhibit proprotein convertase subtilisin-kexin type 9 (PCSK9) are indicated for LDL-C reduction among adult patients with FH, placebo-controlled outcome data among FH patients are scant. OBJECTIVE: Directly compare the efficacy of PCSK9 inhibition as compared to placebo on hard cardiovascular outcomes in FH patients enrolled in the Studies of PCSK9 Inhibition and the Reduction of vascular Events (SPIRE) program. METHODS: We estimated the efficacy of PCSK9 inhibition with bococizumab on future cardiovascular event rates among 1578 FH patients and 15,959 patients without FH who were selected for comparable lipid levels (on-statin levels of LDL-C >100 mg/dL or non-high-density lipoprotein cholesterol > 130 mg/dL). All patients were randomized by computer generated codes to bococizumab 150 mg subcutaneously every 2 weeks or to matching placebo in the SPIRE clinical trials program and were followed over a median period of 11.2 months for major adverse cardiovascular events (nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death). Analysis is by intention to treat. The SPIRE trials are closed and registered at ClinicalTrials.gov: NCT01968954, NCT01968967, NCT02100514, NCT01968980, NCT01975376, and NCT01975389. RESULTS: Compared to non-FH patients, FH patients enrolled in the SPIRE trials were on average younger (58 vs 63 years), more likely to be women (42 vs 35%), more likely to be primary prevention patients (42 vs 23%), had higher mean baseline LDL-C levels (151 vs 127 mg/dL), and lower rates of diabetes (25 vs 52%) and hypertension (59 vs 82%). FH and non-FH patients both had 55% reductions in LDL-C with bococizumab. Among FH patients, major adverse cardiovascular events occurred among 18 of 781 allocated to bococizumab and 22 of 797 allocated to placebo (hazard ratio 0.83; 95% confidence interval 0.44-1.54, P = .55). This best estimate of effect was similar in magnitude to that observed in the much larger group of patients without FH (hazard ratio 0.79, 95% confidence interval 0.64-0.97, P = .023) with no statistically significant evidence of heterogeneity between groups (P = .87). Incidence rate ratios comparing bococizumab to placebo for adverse events were similar among those with and without FH. The proportion of patients developing antidrug antibodies was higher among those with FH compared to those without FH (43% vs 36%, P < .001). CONCLUSIONS: In these randomized placebo-controlled data, the subgroup of statin-treated FH patients had a similar magnitude of risk reduction for hard cardiovascular events with the PCSK9 inhibitor bococizumab as did patients without FH, with no evidence of statistical heterogeneity between groups.

Lipid-Reduction Variability and Antidrug-Antibody Formation with Bococizumab.

BACKGROUND: Bococizumab, a humanized monoclonal antibody targeting proprotein convertase subtilisin-kexin type 9 (PCSK9), reduces levels of low-density lipoprotein (LDL) cholesterol. However, the variability and durability of this effect are uncertain. METHODS: We conducted six parallel, multinational lipid-lowering trials enrolling 4300 patients with hyperlipidemia who were randomly assigned to receive 150 mg of bococizumab or placebo subcutaneously every 2 weeks and who were followed for up to 12 months; 96% were receiving statin therapy at the time of enrollment. The patients were assessed for lipid changes over time, stratified according to the presence or absence of antidrug antibodies detected during the treatment period. RESULTS: At 12 weeks, patients who received bococizumab had a reduction of 54.2% in the LDL cholesterol level from baseline, as compared with an increase of 1.0% among those who received placebo (absolute between-group difference, -55.2 percentage points). Significant between-group differences were also observed in total cholesterol, non-high-density lipoprotein cholesterol, apolipoprotein B, and lipoprotein(a) (P<0.001 for all comparisons). However, high-titer antidrug antibodies developed in a substantial proportion of the patients who received bococizumab, which markedly diminished the magnitude and durability of the reduction in LDL cholesterol levels. In addition, among patients with no antidrug antibodies, there was wide variability in the reduction in LDL cholesterol levels at both 12 weeks and 52 weeks. Major cardiovascular events occurred in 57 patients (2.5%) who received bococizumab and in 55 (2.7%) who received placebo (hazard ratio, 0.96; 95% confidence interval, 0.66 to 1.39; P=0.83). The most common adverse event among patients who received bococizumab was injection-site reaction (12.7 per 100 person-years). CONCLUSIONS: In six multinational trials evaluating bococizumab, antidrug antibodies developed in a large proportion of the patients and significantly attenuated the lowering of LDL cholesterol levels. Wide variation in the relative reduction in cholesterol levels was also observed among patients in whom antidrug antibodies did not develop. (Funded by Pfizer; SPIRE ClinicalTrials.gov numbers, NCT01968954 , NCT01968967 , NCT01968980 , NCT02100514 , NCT02135029 , and NCT02458287 .).

Cardiovascular Efficacy and Safety of Bococizumab in High-Risk Patients.

BACKGROUND: Bococizumab is a humanized monoclonal antibody that inhibits proprotein convertase subtilisin-kexin type 9 (PCSK9) and reduces levels of low-density lipoprotein (LDL) cholesterol. We sought to evaluate the efficacy of bococizumab in patients at high cardiovascular risk. METHODS: In two parallel, multinational trials with different entry criteria for LDL cholesterol levels, we randomly assigned the 27,438 patients in the combined trials to receive bococizumab (at a dose of 150 mg) subcutaneously every 2 weeks or placebo. The primary end point was nonfatal myocardial infarction, nonfatal stroke, hospitalization for unstable angina requiring urgent revascularization, or cardiovascular death; 93% of the patients were receiving statin therapy at baseline. The trials were stopped early after the sponsor elected to discontinue the development of bococizumab owing in part to the development of high rates of antidrug antibodies, as seen in data from other studies in the program. The median follow-up was 10 months. RESULTS: At 14 weeks, patients in the combined trials had a mean change from baseline in LDL cholesterol levels of -56.0% in the bococizumab group and +2.9% in the placebo group, for a between-group difference of -59.0 percentage points (P<0.001) and a median reduction from baseline of 64.2% (P<0.001). In the lower-risk, shorter-duration trial (in which the patients had a baseline LDL cholesterol level of ≥70 mg per deciliter [1.8 mmol per liter] and the median follow-up was 7 months), major cardiovascular events occurred in 173 patients each in the bococizumab group and the placebo group (hazard ratio, 0.99; 95% confidence interval [CI], 0.80 to 1.22; P=0.94). In the higher-risk, longer-duration trial (in which the patients had a baseline LDL cholesterol level of ≥100 mg per deciliter [2.6 mmol per liter] and the median follow-up was 12 months), major cardiovascular events occurred in 179 and 224 patients, respectively (hazard ratio, 0.79; 95% CI, 0.65 to 0.97; P=0.02). The hazard ratio for the primary end point in the combined trials was 0.88 (95% CI, 0.76 to 1.02; P=0.08). Injection-site reactions were more common in the bococizumab group than in the placebo group (10.4% vs. 1.3%, P<0.001). CONCLUSIONS: In two randomized trials comparing the PCSK9 inhibitor bococizumab with placebo, bococizumab had no benefit with respect to major adverse cardiovascular events in the trial involving lower-risk patients but did have a significant benefit in the trial involving higher-risk patients. (Funded by Pfizer; SPIRE-1 and SPIRE-2 ClinicalTrials.gov numbers, NCT01975376 and NCT01975389 .).

Infusion of Reconstituted High-Density Lipoprotein, CSL112, in Patients With Atherosclerosis: Safety and Pharmacokinetic Results From a Phase 2a Randomized Clinical Trial.

BACKGROUND: CSL112 is a new formulation of human apolipoprotein A-I (apoA-I) being developed to reduce cardiovascular events following acute coronary syndrome. This phase 2a, randomized, double-blind, multicenter, dose-ranging trial represents the first clinical investigation to assess the safety and pharmacokinetics/pharmacodynamics of a CSL112 infusion among patients with stable atherosclerotic disease. METHODS AND RESULTS: Patients were randomized to single ascending doses of CSL112 (1.7, 3.4, or 6.8 g) or placebo, administered over a 2-hour period. Primary safety assessments consisted of alanine aminotransferase or aspartate aminotransferase elevations >3× upper limits of normal and study drug-related adverse events. Pharmacokinetic/pharmacodynamic assessments included apoA-I plasma concentration and measures of the ability of serum to promote cholesterol efflux from cells ex vivo. Of 45 patients randomized, 7, 12, and 14 received 1.7-, 3.4-, and 6.8-g CSL112, respectively, and 11 received placebo. There were no clinically significant elevations (>3× upper limit of normal) in alanine aminotransferase or aspartate aminotransferase. Adverse events were nonserious and mild and occurred in 5 (71%), 5 (41%), and 6 (43%) patients in the CSL112 1.7-, 3.4-, and 6.8-g groups, respectively, compared with 3 (27%) placebo patients. The imbalance in adverse events was attributable to vessel puncture/infusion-site bruising. CSL112 resulted in rapid (T(max)≈2 hours) and dose-dependent increases in apoA-I (145% increase in the 6.8-g group) and total cholesterol efflux (up to 3.1-fold higher than placebo) (P<0.001). CONCLUSIONS: CSL112 infusion was well tolerated in patients with stable atherosclerotic disease. CSL112 immediately raised apoA-I levels and caused a rapid and marked increase in the capacity of serum to efflux cholesterol. This potential novel approach for the treatment of atherosclerosis warrants further investigation. CLINICAL TRIAL REGISTRATION: URL: http://www.ClinicalTrials.gov. Unique identifier: NCT01499420.

CSL112 enhances biomarkers of reverse cholesterol transport after single and multiple infusions in healthy subjects.

OBJECTIVE: The ability of apolipoprotein A-I (apoA-I) to transport cholesterol from atherosclerotic plaque is thought to underlie its inverse correlation with cardiovascular risk. To gauge the potential of infused apoA-I to transport cholesterol, we quantified cholesterol transport markers in human subjects infused with a novel formulation of apoA-I (CSL112). APPROACH AND RESULTS: CSL112 was infused into human subjects in single (57 subjects) and multiple (36 subjects) ascending dose trials. Pharmacokinetic and biomarker assessments were conducted before and after infusions. CSL112 caused an immediate, up to 3-fold elevation of apoA-I and subsequent movement of tissue cholesterol into plasma. Cholesterol appeared first as unesterified cholesterol in the high-density lipoprotein (HDL) fraction and was promptly esterified by lecithin cholesterol acyltransferase. HDL cholesterol increased up to 81±16.5%. Underlying this movement of cholesterol was an immediate and strong rise in the ability of plasma to promote cholesterol efflux from cells ex vivo. CSL112 had its greatest impact on the fraction of efflux mediated by ATP-binding cassette transporter A1 (ABCA1), a cholesterol transporter induced in cholesterol-loaded tissues such as plaque. ABCA1-dependent efflux capacity increased ≤630±421% and total efflux capacity by ≤192±40%. In keeping with this finding, we observed a profound rise in very small HDL, also known as preß1-HDL, the preferred substrate for ABCA1. Very small HDL increased ≤3596±941%. Elevations in apoA-I, cholesterol efflux, and very small HDL were dose-proportional over a wide range. No significant changes in atherogenic lipids were observed at any dose. CONCLUSIONS: Infusion of CSL112 elevates the ability of plasma to withdraw cholesterol from cells. Preferential elevation of ABCA1-dependent efflux may target atherosclerotic plaque for cholesterol removal, making CSL112 a promising candidate therapy for acute coronary syndrome.

Relationship between atorvastatin dose and the harm caused by torcetrapib.

Development of the cholesteryl ester transfer protein (CETP) inhibitor, torcetrapib, was halted after the ILLUMINATE trial revealed an increase in both all-cause mortality (ACM) and major cardiovascular events (MCVEs) associated with its use. We now report that the harm caused by torcetrapib was confined to those in the 10 mg atorvastatin subgroup for both ACM [hazard ratio (HR) = 2.68, 95% CI (1.58, 4.54), P < 0.0001] and MCVEs [HR = 1.41, 95% CI (1.14, 1.74), P = 0.002], with no evidence of harm when torcetrapib was coadministered with higher doses of atorvastatin. In the atorvastatin 10 mg subgroup, age, prior heart failure and stroke were significantly associated with ACM, independent of torcetrapib treatment, whereas low apoA-I, smoking, hypertension, heart failure, myocardial infarction, and stroke were independently associated with MCVEs. After adjusting for these factors, the HR associated with torcetrapib treatment in the 10 mg atorvastatin subgroup remained elevated for both ACM [HR = 2.67, 95% CI (1.57, 4.54), P < 0.001] and MCVE [HR = 1.36, 95% CI (1.10, 1.69), P = 0.005]. Thus, the harm caused by torcetrapib was confined to individuals taking atorvastatin 10 mg. The harm could not be explained by torcetrapib-induced changes in lipid levels, blood pressure, or electrolytes. It is conceivable that higher doses of atorvastatin protected against the harm caused by torcetrapib.

Ultrasound protocols to measure carotid intima-media thickness in trials; comparison of reproducibility, rate of progression, and effect of intervention in subjects with familial hypercholesterolemia and subjects with mixed dyslipidemia.

BACKGROUND: Current ultrasound protocols to measure carotid intima-media thickness (CIMT) in trials rather differ. The ideal protocol combines high reproducibility with a high precision in the measurement of the rate of change in CIMT over time and with a precise estimate of a treatment effect. To study these aspects, a post-hoc analysis was performed using data from two randomized double-blind, placebo-controlled trials: one among 872 subjects with familial hypercholesterolemia (FH) and the other among 752 subjects with mixed dyslipidemia (MD), respectively. Participants were randomized to torcetrapib or placebo on top of optimal atorvastatin therapy. METHODS: CIMT information was collected from the left and right carotid artery from two walls (the near and far wall) of three segments (common carotid, bifurcation, and internal carotid artery) at four different angles (right: 90, 120, 150, and 180 degrees on Meijer's carotid arc; left: 270, 240, 210, and 180 degrees, respectively). Based on combinations of these measurements, 60 different protocols were constructed to estimate a CIMT measure per participant (20 protocols for mean common CIMT, 40 protocols for mean maximum CIMT). For each protocol we assessed reproducibility (intra-class correlation coefficient (ICC), mean difference of duplicate base-line scans); 2-year progression rate in the atorvastatin group with its standard error (SE); and treatment effect (difference in rate of change in CIMT between torcetrapib and placebo) with its SE. RESULTS: Reproducibility: ICC ranged from 0.77 to 0.91 among FH patients and from 0.68 to 0.86 among MD patients. CIMT progression rates ranged from -0.0030 to 0.0020 mm/year in the FH trial and from 0.00084 to 0.01057 mm/year in the MD trial, with SE ranging from 0.00054 to 0.00162 and from 0.00083 to 0.00229, respectively. The difference in CIMT progression rate between treatment arms ranged from -0.00133 to 0.00400 mm/year in the FH trial and from -0.00231 to 0.00486 mm/year in the MD trial. The protocol with the highest reproducibility, highest CIMT progression/precision ratio, and the highest treatment effect/precision ratio were those measuring mean common CIMT with measurements of the near and far wall at multiple angles. When the interest is in the mean maximum CIMT, protocols using multiple segments and angles performed the best. CONCLUSION: Our findings support the position that the number and specific combination of segments, angles, and walls interrogated are associated with differences in reproducibility, magnitude, and precision of progression of CIMT over time, and treatment effect. The best protocols were mean common CIMT protocols in which both the near and far walls are measured at multiple angles.

Completeness of carotid intima media thickness measurements depends on body composition: the RADIANCE 1 and 2 trials.

AIM: Ultrasound protocols to measure carotid intima media thickness (CIMT) differ considerably with regard to the inclusion of the number of carotid segments and angles used. Detailed information on the completeness of CIMT information is often lacking in published reports, and at most, overall percentages are presented. We therefore decided to study the completeness of CIMT measurements and its relation with vascular risk factors using data from two CIMT intervention studies: one among familial hypercholesterolemia (FH) patients, the Rating Atherosclerotic Disease change by Imaging With A New CETP Inhibitor (RADIANCE 1), and one among mixed dyslipidemia (MD) patients, the Rating Atherosclerotic Disease change by Imaging With A New CETP Inhibitor (RADIANCE 2). METHODS: We used baseline ultrasound scans from the RADIANCE 1 (n=872) and RADIANCE 2 (n=752) studies. CIMT images were recorded for 12 artery-wall combinations (near and far walls of the left and right common carotid artery (CCA), bifurcation (BIF) and internal carotid artery (ICA) segments) at 4 set angles, resulting in 48 possible measurements per patient. The presence or absence of CIMT measurements was assessed per artery-wall combination and per angle. The relation between completeness and patient characteristics was evaluated with logistic regression analysis. RESULTS: In 89% of the FH patients, information on CIMT could be obtained on all twelve carotid segments, and in 7.6%, eleven segments had CIMT information (nearly complete 96.6%). For MD patients this was 74.6% and 17.9%, respectively (nearly complete: 92.5%). Increased body mass index and increased waist circumference were significantly (p=0.01) related to less complete data in FH patients. For MD patients, relations were seen with increased waist circumference (p<0.01). Segment-specific data indicated that in FH patients, completeness was less for the near wall of the left (96%) and right internal carotid artery (94%) as compared to other segments (all >98%). In MD patients, completeness was lower for the near wall of both the right and left carotid arteries: 86.0% and 90.8%, respectively, as compared to other segments (all >97%). CONCLUSIONS: With the current ultrasound protocols it is possible to obtain a very high level of completeness. Apart from the population studied, body mass index and waist circumference are important in achieving complete CIMT measurements.

Inhibition of CETP by torcetrapib attenuates the atherogenicity of postprandial TG-rich lipoproteins in type IIB hyperlipidemia.

OBJECTIVE: The purpose of this study was to evaluate the impact of torcetrapib on atherogenic TG-rich lipoprotein subfractions in the postprandial phase in Type IIB hyperlipidemia. METHODS AND RESULTS: The quantitative and qualitative features of the postprandial profile of TG-rich lipoproteins were determined at baseline, after treatment for 6 weeks with 10 mg/d atorvastatin, and subsequently with an atorvastatin/torcetrapib combination (10/60 mg/d) in Type IIB patients (n=18). After ingestion of a standardized mixed meal, TG-rich lipoprotein subfractions were evaluated over 8 hours after each experimental period. On a background of atorvastatin, torcetrapib significantly attenuated the incremental postprandial area under the curve (iAUC 0 to 8 hours) for VLDL-1 (-40%), and the AUC 0 to 8 hours for VLDL-2 (-53%), with minor effect on chylomicron iAUC (-24%); concomitantly, the CE/TG ratio in both VLDL-1 and VLDL-2 was significantly reduced (-27% to -42%). Such reduction was attributable to torcetrapib-mediated attenuation of postprandial CE transfer to Chylomicrons (-17%) and VLDL-1 (-33%). Marked reduction in postprandial VLDL-1 levels was associated with apoE enrichment. CONCLUSIONS: On a background of atorvastatin, torcetrapib attenuated the quantitative and qualitative features of the atherogenic postprandial profile of chylomicrons, VLDL-1 and VLDL-2. Such changes reflect the sum of torcetrapib-mediated effects on TG-rich lipoprotein production, intravascular remodeling, and catabolism.

Effects of torcetrapib in patients at high risk for coronary events.

BACKGROUND: Inhibition of cholesteryl ester transfer protein (CETP) has been shown to have a substantial effect on plasma lipoprotein levels. We investigated whether torcetrapib, a potent CETP inhibitor, might reduce major cardiovascular events. The trial was terminated prematurely because of an increased risk of death and cardiac events in patients receiving torcetrapib. METHODS: We conducted a randomized, double-blind study involving 15,067 patients at high cardiovascular risk. The patients received either torcetrapib plus atorvastatin or atorvastatin alone. The primary outcome was the time to the first major cardiovascular event, which was defined as death from coronary heart disease, nonfatal myocardial infarction, stroke, or hospitalization for unstable angina. RESULTS: At 12 months in patients who received torcetrapib, there was an increase of 72.1% in high-density lipoprotein cholesterol and a decrease of 24.9% in low-density lipoprotein cholesterol, as compared with baseline (P<0.001 for both comparisons), in addition to an increase of 5.4 mm Hg in systolic blood pressure, a decrease in serum potassium, and increases in serum sodium, bicarbonate, and aldosterone (P<0.001 for all comparisons). There was also an increased risk of cardiovascular events (hazard ratio, 1.25; 95% confidence interval [CI], 1.09 to 1.44; P=0.001) and death from any cause (hazard ratio, 1.58; 95% CI, 1.14 to 2.19; P=0.006). Post hoc analyses showed an increased risk of death in patients treated with torcetrapib whose reduction in potassium or increase in bicarbonate was greater than the median change. CONCLUSIONS: Torcetrapib therapy resulted in an increased risk of mortality and morbidity of unknown mechanism. Although there was evidence of an off-target effect of torcetrapib, we cannot rule out adverse effects related to CETP inhibition. (ClinicalTrials.gov number, NCT00134264 [ClinicalTrials.gov].).

Torcetrapib and carotid intima-media thickness in mixed dyslipidaemia (RADIANCE 2 study): a randomised, double-blind trial.

BACKGROUND: Patients with mixed dyslipidaemia have raised triglycerides, low high-density lipoprotein (HDL) cholesterol, and high low-density lipoprotein (LDL) cholesterol. Augmentation of HDL cholesterol by inhibition of the cholesteryl ester transfer protein (CETP) could benefit these patients. We aimed to investigate the effect of the CETP inhibitor, torcetrapib, on carotid atherosclerosis progression in patients with mixed dyslipidaemia. METHODS: We did a randomised double-blind trial at 64 centres in North America and Europe. 752 eligible participants completed an atorvastatin-only run-in period for dose titration, after which they all continued to receive atorvastatin at the titrated dose. 377 of these patients were randomly assigned to receive 60 mg of torcetrapib per day and 375 to placebo. We made carotid ultrasound images at baseline and at 6-month intervals for 24 months. The primary endpoint was the yearly rate of change in the maximum intima-media thickness of 12 carotid segments. Analysis was restricted to 683 patients who had at least one dose of treatment and had at least one follow-up carotid intima-media measurement; they were analysed as randomised. Mean follow-up for these patients was 22 (SD 4.8) months. This trial is registered with ClinicalTrials.gov, number NCT00134238. FINDINGS: The change in maximum carotid intima-media thickness was 0.025 (SD 0.005) mm per year in patients given torcetrapib with atorvastatin and 0.030 (0.005) mm per year in those given atorvastatin alone (difference -0.005 mm per year, 95% CI -0.018 to 0.008, p=0.46). Patients in the combined-treatment group had a 63.4% relative increase in HDL cholesterol (p<0.0001) and an 17.7% relative decrease in LDL cholesterol (p<0.0001), compared with controls. Systolic blood pressure increased by 6.6 mm Hg in the combined-treatment group and 1.5 mm Hg in the atorvastatin-only group (difference 5.4 mm Hg, 95% CI 4.3-6.4, p<0.0001). INTERPRETATION: Although torcetrapib substantially raised HDL cholesterol and lowered LDL cholesterol, it also increased systolic blood pressure, and did not affect the yearly rate of change in the maximum intima-media thickness of 12 carotid segments. Torcetrapib showed no clinical benefit in this or other studies, and will not be developed further.

Designs of RADIANCE 1 and 2: carotid ultrasound studies comparing the effects of torcetrapib/atorvastatin with atorvastatin alone on atherosclerosis.

OBJECTIVE: The RADIANCE studies were designed to assess the effects of torcetrapib/atorvastatin (T/A) compared with atorvastatin alone on slowing atherosclerotic progression in patients with heterozygous familial hypercholesterolemia (RADIANCE 1) or mixed hyperlipidemia (RADIANCE 2), as measured by change in carotid intima-media thickness (CIMT). RESEARCH DESIGN AND METHODS: RADIANCE 1 and 2 were randomized, double-blind, controlled trials with a duration of 2 years. In both studies, eligible subjects began treatment with atorvastatin during a run-in period and were titrated to target LDL-C levels defined by NCEP ATP III guidelines. Subjects then proceeded to a double-blind randomized treatment period where they received one of two regimens: (i) fixed combination T/A (torcetrapib dose, 60 mg), or (ii) atorvastatin alone. In both regimens, the dose of atorvastatin was established during the run-in period (20-80 mg, RADIANCE 1; 10-80 mg RADIANCE 2). B-mode ultrasonography was performed in duplicate at baseline and at end of study, and every 6 months in between. MAIN OUTCOME MEASURES: The primary efficacy measure in both studies was the annualized rate of change in maximum CIMT of 12 pre-defined carotid segments. Further outcome measures included lipid and safety assessments. CURRENT STATUS: The number of subjects randomized was 904 in RADIANCE 1 and 752 in RADIANCE 2. Results are anticipated in 2007.

Biomarkers in the prevention and treatment of atherosclerosis: need, validation, and future.

Cardiovascular disease (CVD) remains one of the leading causes of morbidity and mortality in the developed world, and there is a clear need to develop novel therapeutic strategies to reduce cardiovascular risk further than is currently possible. Traditionally, the effectiveness of new cardiovascular drugs has been evaluated in clinical trials using cardiovascular outcomes as endpoints. However, such trials require large numbers of patients followed over long periods of time. Clinical trials using surrogate markers for CVD may be shorter in duration and involve fewer participants. Measurement of atherosclerotic progression is an ideal surrogate marker as it is predictive of future cardiovascular events. The "gold standard" for detecting and defining the severity, extent, and rate of atherosclerotic progression has been quantitative coronary angiography. However, this technique has fundamental limitations. More recently, measurement of carotid intima-media thickness using B-mode ultrasound and measurement of atheroma volume using intravascular ultrasound have emerged as more accurate techniques for detecting atherosclerotic progression. Both of these techniques have potential utility as surrogate endpoints in place of cardiovascular outcomes in clinical trials. Their use might facilitate the more rapid development of novel, safe, and effective therapies.

Effect of torcetrapib on the progression of coronary atherosclerosis.

BACKGROUND: Levels of high-density lipoprotein (HDL) cholesterol are inversely related to cardiovascular risk. Torcetrapib, a cholesteryl ester transfer protein (CETP) inhibitor, increases HDL cholesterol levels, but the functional effects associated with this mechanism remain uncertain. METHODS: A total of 1188 patients with coronary disease underwent intravascular ultrasonography. After treatment with atorvastatin to reduce levels of low-density lipoprotein (LDL) cholesterol to less than 100 mg per deciliter (2.59 mmol per liter), patients were randomly assigned to receive either atorvastatin monotherapy or atorvastatin plus 60 mg of torcetrapib daily. After 24 months, disease progression was measured by repeated intravascular ultrasonography in 910 patients (77%). RESULTS: After 24 months, as compared with atorvastatin monotherapy, the effect of torcetrapib-atorvastatin therapy was an approximate 61% relative increase in HDL cholesterol and a 20% relative decrease in LDL cholesterol, reaching a ratio of LDL cholesterol to HDL cholesterol of less than 1.0. Torcetrapib was also associated with an increase in systolic blood pressure of 4.6 mm Hg. The percent atheroma volume (the primary efficacy measure) increased by 0.19% in the atorvastatin-only group and by 0.12% in the torcetrapib-atorvastatin group (P=0.72). A secondary measure, the change in normalized atheroma volume, showed a small favorable effect for torcetrapib (P=0.02), but there was no significant difference in the change in atheroma volume for the most diseased vessel segment. CONCLUSIONS: The CETP inhibitor torcetrapib was associated with a substantial increase in HDL cholesterol and decrease in LDL cholesterol. It was also associated with an increase in blood pressure, and there was no significant decrease in the progression of coronary atherosclerosis. The lack of efficacy may be related to the mechanism of action of this drug class or to molecule-specific adverse effects. (ClinicalTrials.gov number, NCT00134173 [ClinicalTrials.gov].).

Effect of torcetrapib on carotid atherosclerosis in familial hypercholesterolemia.

BACKGROUND: Torcetrapib, an inhibitor of cholesteryl ester transfer protein, may reduce atherosclerotic vascular disease by increasing levels of high-density lipoprotein (HDL) cholesterol. METHODS: A total of 850 patients with heterozygous familial hypercholesterolemia underwent B-mode ultrasonography at baseline and at follow-up to measure changes in carotid intima-media thickness. The patients completed an atorvastatin run-in period and were subsequently randomly assigned to receive either atorvastatin monotherapy or atorvastatin combined with 60 mg of torcetrapib for 2 years. RESULTS: After 24 months, in the atorvastatin-only group, the mean (+/-SD) HDL cholesterol level was 52.4+/-13.5 mg per deciliter and the mean low-density lipoprotein (LDL) cholesterol level was 143.2+/-42.2 mg per deciliter, as compared with 81.5+/-22.6 mg per deciliter and 115.1+/-48.5 mg per deciliter, respectively, in the torcetrapib-atorvastatin group. During the study, average systolic blood pressure increased by 2.8 mm Hg in the torcetrapib-atorvastatin group, as compared with the atorvastatin-only group. The increase in maximum carotid intima-media thickness, the primary measure of efficacy, was 0.0053+/-0.0028 mm per year in the atorvastatin-only group and 0.0047+/-0.0028 mm per year in the torcetrapib-atorvastatin group (P=0.87). The secondary efficacy measure, annualized change in mean carotid intima-media thickness for the common carotid artery, indicated a decrease of 0.0014 mm per year in the atorvastatin-only group, as compared with an increase of 0.0038 mm per year in the torcetrapib-atorvastatin group (P=0.005). CONCLUSIONS: In patients with familial hypercholesterolemia, the use of torcetrapib with atorvastatin, as compared with atorvastatin alone, did not result in further reduction of progression of atherosclerosis, as assessed by a combined measure of carotid arterial-wall thickness, and was associated with progression of disease in the common carotid segment. These effects occurred despite a large increase in HDL cholesterol levels and a substantial decrease in levels of LDL cholesterol and triglycerides. (ClinicalTrials.gov number, NCT00136981 [ClinicalTrials.gov].).

Inhibition of cholesteryl ester transfer protein by torcetrapib modestly increases macrophage cholesterol efflux to HDL.

OBJECTIVE: This study examines the effects of pharmacological inhibition of cholesteryl ester transfer protein (CETP) on the ability of high-density lipoprotein particles (HDL) to promote net cholesterol efflux from human THP-1 macrophage foam cells. METHODS AND RESULTS: Two groups of 8 healthy, moderately hyperlipidemic subjects received the CETP inhibitor torcetrapib at 60 or 120 mg daily for 8 weeks. Torcetrapib increased HDL cholesterol levels in both groups by 50% and 60%, respectively. Compared with baseline, torcetrapib 60 mg daily increased HDL-mediated net cholesterol efflux from foam cells primarily by increasing HDL concentrations, whereas 120 mg daily torcetrapib increased cholesterol efflux both by increasing HDL concentration and by causing increased efflux at matched HDL concentrations. There was an increased content of lecithin:cholesterol acyltransferase (LCAT) and apolipoprotein E (apoE) in HDL-2 only at the 120 mg dose. ABCG1 activity was responsible for 40% to 50% of net cholesterol efflux to both control and T-HDL. CONCLUSIONS: These data indicate that inhibition of CETP by torcetrapib causes a modest increase in the ability of HDL to promote net cholesterol efflux at the 60 mg dose, and a more dramatic increase at the 120 mg dose in association with enhanced particle functionality.

Efficacy and safety of torcetrapib, a novel cholesteryl ester transfer protein inhibitor, in individuals with below-average high-density lipoprotein cholesterol levels.

OBJECTIVES: This study was designed to evaluate the efficacy and safety of torcetrapib, a cholesteryl ester transfer protein (CETP) inhibitor, in subjects with low high-density lipoprotein cholesterol (HDL-C) levels. BACKGROUND: Evidence suggests HDL-C is atheroprotective. A proven mechanism for increasing the level of HDL-C is the inhibition of CETP. METHODS: A total of 162 subjects with below-average HDL-C (men <44 mg/dl; women <54 mg/dl) who were not taking lipid-modifying therapy were randomized to double-blind treatment with torcetrapib 10, 30, 60, or 90 mg/day or placebo ( approximately 30 subjects per group). RESULTS: The percent change from baseline to Week 8 with torcetrapib (least-squares mean difference from placebo) was dose-dependent and ranged from 9.0% to 54.5% for HDL-C (p < or = 0.0001 for 30 mg and higher doses) and from 3.0% to -16.5% for low-density lipoprotein cholesterol (LDL-C) (p < 0.01 for 90-mg dose). Low-density lipoprotein cholesterol lowering was less in subjects with higher (>150 mg/dl) versus lower levels of baseline triglycerides; at 60 mg, the change in LDL-C was 0.1% versus -22.2% (p < 0.0001), respectively. Particle size for both HDL and LDL increased with torcetrapib. There were no dose-related increases in the frequency of adverse events. Significant blood pressure increases were noted in 2 of 140 subjects. CONCLUSIONS: Torcetrapib resulted in substantial dose-dependent elevations in HDL-C, accompanied by moderate decreases in LDL-C at the higher doses. Torcetrapib was generally well tolerated.

Efficacy and safety of torcetrapib, a novel cholesteryl ester transfer protein inhibitor, in individuals with below-average high-density lipoprotein cholesterol levels on a background of atorvastatin.

OBJECTIVES: This study sought to evaluate the efficacy and safety of torcetrapib in patients with low high-density lipoprotein cholesterol (HDL-C) levels receiving background atorvastatin. BACKGROUND: Elevating HDL-C levels may reduce the residual cardiovascular risk that is observed in patients treated with statin therapy. Torcetrapib (a cholesteryl ester transfer protein inhibitor) increases HDL-C and decreases low-density lipoprotein cholesterol (LDL-C). METHODS: This was a multicenter, double-blind, randomized trial. Patients with below-average HDL-C (men <44 mg/dl; women <54 mg/dl) who were eligible for statin therapy according to National Cholesterol Education Program Adult Treatment Panel III guidelines or who had LDL-C >130 mg/dl at screening entered an 8-week run-in period with atorvastatin 20 mg/day before randomization (n = 174) to torcetrapib 10, 30, 60, or 90 mg/day or placebo for 8 weeks. Atorvastatin was continued during treatment with torcetrapib. RESULTS: After 8 weeks, the percent change from baseline with torcetrapib (least-squares mean difference from placebo) ranged from 8.3% to 40.2% for HDL-C (p < or = 0.0001 for 30-mg and higher doses) and from 0.6% to -18.9% for LDL-C (p < 0.01 for 60-mg and 90-mg doses). Particle size for both HDL and LDL increased with torcetrapib. The incidence of all-causality and treatment-related adverse events was similar across placebo and torcetrapib treatment groups with no evidence of a dose-related response. In some treatment groups, small increases in systolic and diastolic blood pressures were noted. CONCLUSIONS: In statin-eligible patients, torcetrapib plus background atorvastatin resulted in substantial, dose-dependent increases in HDL-C, accompanied by additional decreases in LDL-C beyond those seen with atorvastatin alone. Torcetrapib plus atorvastatin was generally well tolerated.