Efficacy and Safety of Lovastatin in Adolescent Males With Heterozygous Familial Hypercholesterolemia: Title and subTitle BreakA Randomized Controlled Trial FREE

Familial hypercholesterolemia (FH) is a dominant genetic disorder first described by Muller¹ nearly 60 years ago. The elevated circulating low-density lipoprotein cholesterol (LDL-C) levels found in FH are caused by a defect in receptor-mediated LDL clearance² and are the underlying cause of the marked increase in early coronary artery disease (CAD).³ In men with untreated heterozygous FH (HeFH), the risk of clinically overt CAD is approximately 5% by age 30 years, 20% by age 40 years, and 50% by age 50 years.^{3 - 4} Only about 15% of men with HeFH reach age 65 years without experiencing an ischemic coronary event.⁴ If left untreated, 23% of men experience fatal coronary events by age 50 years. Furthermore, the location and extent of coronary lesions in patients with HeFH suggest a prognosis worse than that of patients without FH; in 1 study, 70% of patients with HeFH had triple-vessel CAD and 32% had left main vessel disease.⁵

In the vast majority of patients, a diet low in saturated fat and cholesterol has only a small effect on reduction of LDL-C levels.^{6 - 7} Lipid-lowering treatment in select children with HeFH is considered medically appropriate,⁸ although there is no consensus on the age at which drug therapy should be started. The US National Cholesterol Education Program Pediatric Treatment Panel recommended drug therapy be considered if, after diet, LDL-C level remains higher than 4.2 mmol/L (160 mg/dL) with a family history of premature CAD or 4.9 mmol/L (190 mg/dL) without such history.⁸ Bile-acid sequestrants have been considered the drugs of choice and have been used in children with FH for more than 20 years.^{9 - 10} These sequestrants appear safe, but their LDL-C–lowering effects are modest and long-term compliance is a major problem.^{9 - 10} The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have been in widespread clinical use in adults for more than a decade¹¹ and have been shown to be safe and effective therapy for the reduction of total cholesterol and LDL-C levels. Recent large, end point–based clinical trials have demonstrated significant reductions in cardiovascular mortality and/or morbidity in trials assessing both primary¹² and secondary¹³ prevention of morbidity.

Information on the effect of statins in a pediatric population has been limited to small observational reports^{14 - 15} and short-term placebo-controlled studies.^{16 - 17} The present article describes a 1-year, double-blind, placebo-controlled, randomized study of 132 adolescent boys with severe HeFH, designed to assess the lipid-lowering efficacy of lovastatin and its effect on growth, sexual maturation, and biochemical, nutritional, and endocrine parameters.

The study was reviewed and approved by each local center's institutional review board. Written parental or guardian consent was obtained for each subject prior to his entry into the study at each of the 14 centers. Adolescent boys aged 10 to 17 years who followed the American Heart Association (AHA) pediatric diet¹⁸ for at least 4 months were considered to have HeFH if their LDL-C values were at least 4.9 mmol/L (189 mg/dL) and no more than 13.0 mmol/L (503 mg/dL) and at least 1 parent had an LDL-C value of at least 4.9 mmol/L (189 mg/dL) not associated with a disorder known to cause secondary LDL-C elevation, or if their LDL-C values were at least 5.7 mmol/L (220 mg/dL) and no more than 13.0 mmol/L (503 mg/dL) and a parent had died of CAD with no available lipid values. These LDL-C entry criteria were to be met at both week −4 and week −2 (prebaseline).

To follow sexual maturation, patients were prepubertal or pubertal (Tanner stage I-IV) on recruitment. Subsequently, the US Food and Drug Administration (FDA) requested that subjects who had not reached Tanner stage II at entry discontinue the trial. This request resulted in the discontinuation of 8 subjects (7 in the placebo group and 1 in the lovastatin group). Subjects with a testicular volume of no more than 3 cm³ after age 12 years were excluded for delayed puberty, as were those weighing less than 32 kg or whose weight was less than the 10th or more than the 95th weight percentiles for age. Additional exclusion criteria were homozygous FH, underlying disorders known to produce secondary LDL-C elevations, or disorders primarily affecting triglyceride-rich lipoproteins (chylomicrons, very low-density lipoprotein, or intermediate-density lipoprotein).

Study Design. Eligible subjects as described herein received formal dietary reinstruction, were monitored, and were determined to be stable following an AHA pediatric diet¹⁸ for at least 8 weeks prior to randomization. Placebo was administered during the final 4 weeks (week −4 to week 0). Subjects were then randomized (Figure 1) to either active treatment (arm 1) or placebo (arm 2). Within the active treatment group, the dosage of lovastatin was started at 10 mg/d and increased at 8-week intervals (weeks 8 and 16) to 20 and 40 mg/d, respectively. Subjects in the placebo arm received matching placebo tablets throughout the first 24 weeks (period 1). During the next 24 weeks (weeks 25-48; period 2), subjects in the active treatment arm received 40 mg/d of lovastatin while those in the placebo group continued to receive placebo. All subjects continued to receive diet instruction, monitoring, and evaluation throughout the study. Quantitative dietary analysis was carried out at a central facility (Metabolic and Atherosclerosis Research Center, Cincinnati, Ohio).

Clinical Monitoring. Subjects were seen every 4 weeks throughout the first 24-week period and every 6 weeks during the second 24-week period for clinical assessment and blood lipid and laboratory measurements, including hepatic transaminases (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) and creatine kinase (CK). Sexual maturation was evaluated using Tanner staging¹⁹ at entry (week 0) and after 24 and 48 weeks of treatment. Testicular volume was assessed by comparison with a standardized set of wooden beads (Orchidometer, Kabi, Japan). Height was measured using a stadiometer (University of Iowa, Iowa City) and weight was monitored by regularly calibrated scales.

Dietary review and reinforcement by a registered dietitian was carried out at weeks −8, −4, 0, 8, 16, 24, 30, 36, 42, and 48. Lovastatin or matching placebo was taken immediately prior to the evening meal. Compliance was assessed by tablet count at every visit.

Laboratory Testing. At each visit, blood was obtained after an overnight fast. Serum chemistry (including hepatic transaminases and CK) and plasma lipids were measured at each visit. Routine hematology was assessed at baseline and every 12 weeks thereafter. At weeks 0, 24, and 48, values were determined for the following parameters: blood coagulation; urinalysis; thyroid function; blood nutrients (ferritin and vitamins A, D, and E); adrenal (cortisol and dehydroepiandrosterone sulfate [DHEAS]), gonadal (testosterone), and pituitary (follicle-stimulating hormone [FSH] and luteinizing hormone [LH]) hormones; and apolipoproteins (apo) A-I, A-II, B, and lipoprotein(a) (Lp[a]). All laboratory measurements were carried out at a central laboratory (Medical Research Laboratories, Highland Heights, Ky).

Blood samples were centrifuged immediately after collection to isolate plasma or serum. Samples were transported overnight at 4°C and analyzed immediately on receipt, except for coagulation and special hormone testing, for which samples were frozen (−20°C) at the clinics and transported at regular intervals on dry ice to the central laboratory for analysis. Total cholesterol and triglycerides were analyzed by enzymatic methods on a Hitachi 737 analyzer (Boehringer Mannheim Diagnostics, Indianapolis, Ind) as previously described.²⁰ The laboratory participated in and remained certified by the National Heart, Lung, and Blood Institute–Centers for Disease Control and Prevention Part III program²¹ throughout the study. High-density lipoprotein cholesterol (HDL-C) was isolated using heparin-2M manganese chloride.²² Apolipoprotein A-I, A-II, B, and Lp(a) analyses were performed using competitive enzyme-linked immunosorbent assay procedures.^{23 - 25}

Routine hematology and serum chemistries and enzymes were analyzed on a Coulter STKS (Coulter Corp, Hialeah, Fla) and Hitachi 747 (Boehringer Mannheim Diagnostics), respectively, by well-standardized procedures in the College of American Pathologists–accredited central laboratory. Retinol, tocopherols, and carotene were analyzed by high-performance liquid chromatography as previously described,²⁶ with the laboratory participating in an external monitoring program by the National Institutes of Standards and Technology. 25-Hydroxyvitamin D was measured by radioimmunoassay (Nichols Institute Diagnostics, Los Angeles, Calif); ferritin, thyroxine, and triiodothyronine resin uptake by microparticle enzyme immunoassay (IMx, Abbott Diagnostics, North Chicago, Ill); and thyrotropin, DHEAS, cortisol, testosterone, FSH, and LH by radioimmunoassay (Diagnostics Products Corp, Los Angeles).

Statistics. For efficacy analysis, participants with a baseline value who had completed at least one 8-week phase of the study were included. Patients needed to complete subsequent 8-week phases to be included in the associated summary statistics.

For safety, analysis was carried out on an intent-to-treat basis, in which all subjects randomized to double-blind therapy were included. Means and SEs were computed for each parameter at each point (baseline and weeks 8, 16, 24, and 48). Median, first-quartile, and third-quartile values were determined for all endocrine function parameters (testosterone, DHEAS, cortisol, FSH, and LH). Percentage changes from baseline were also calculated for each treatment group for the parameters of efficacy, safety (ALT, AST, CK), growth (height), and sexual development (testicular volume). The Wilcoxon rank sum statistic²⁷ was used to test for treatment differences between treatment groups for the following efficacy parameters: total cholesterol, triglycerides, LDL-C, HDL-C, apo B, apo A-I, apo A-II, and Lp(a), as well as the endocrine function and nutritional parameters. Analysis of variance was used to examine the growth parameters (height, weight, testicular volume, and Quetelet index). The Cochran-Mantel-Haenszel test statistic²⁸ was used for testing for treatment differences in Tanner staging between lovastatin and placebo. Differences in new or worsening adverse experiences were compared using the Fisher exact test²⁹ on both the total number of patients and by organ systems. The power to detect a difference in the safety parameters was not a primary consideration in the design of the study. Low power was observed for almost all of the safety parameters and ranged from 5% to 88%.

Family history was obtained in 97 (74%) of the 132 randomized subjects. The parent with FH was the mother in 54 cases (56%) and the father in 43 cases (44%). Evidence of CAD was present in 36 parents (37%; 59% of fathers with FH and 19% of mothers with FH). The mean age of onset of CAD of the affected parents was 37 years. Eight fathers with FH (20% of FH carriers) had died due to CAD; the mean age of death was 39 years. No mothers with FH had died due to CAD.

Table 1 shows baseline demographic features at entry and indicates balance between the randomized groups. One hundred twenty-three (93%) of 132 randomized subjects were white. One hundred twenty-two (92%) completed period 1 and 110 (83%) completed the entire 48-week study; there were 6 and 16 discontinuations in the lovastatin and placebo groups, respectively. These were due to withdrawal of consent (lovastatin, 4; placebo, 5), FDA request (lovastatin, 1; placebo, 7), deviation from protocol (placebo, 2), and adverse events (lovastatin, 1; placebo, 2).

Baseline lipid and apolipoprotein concentrations are shown in Table 1. Levels of total cholesterol, LDL-C, and apo B were markedly elevated, consistent with the stringent entry criteria. Mean HDL-C values were between the 25th and 50th percentiles by age and sex, while mean triglyceride values were at the 95th percentile.³⁰ Apolipoprotein A-I concentrations tended to be slightly low³¹ and apo A-II values were average. Lipoprotein(a) levels were elevated (>0.2 g/L [20 mg/dL]) in concentration in almost half the subjects and were higher than 0.3 g/L (30 mg/dL) in more than 25% of the subjects.

Period 1 (0-24 Weeks).Table 2 shows lipid and apolipoprotein changes after 8 weeks of treatment with dosages of 10, 20, and 40 mg/d of lovastatin or matching placebo. Lovastatin produced reductions in LDL-C and total cholesterol levels at all dosages (P<.001 vs placebo; Table 2), and in apo B at 40 mg/d (apo B was not measured during treatment with the lower dosage). An approximate 6% additional LDL-C lowering occurred with each doubling of lovastatin dosage. Minimal and nonsignificant (P>.05) increases occurred in HDL-C and triglycerides compared with placebo and were not dose-related. No changes were seen in Lp(a) in either group.

Period 2 (24-48 Weeks). Continued therapy with lovastatin, 40 mg/d, produced reductions in levels of LDL-C and apo B of 25% and 22%, respectively (P<.001 vs placebo for both; Table 2). There were no significant changes in the other lipids and apolipoproteins.

Lovastatin had no significant effect on the growth parameters at 24 and 48 weeks (Table 3). Furthermore, compared with expected individual growth rates monitored on percentile growth charts, neither group showed significant deviations.

Sexual maturation was assessed clinically by changes in both testicular volume and Tanner staging. During 24 and 48 weeks of observation, subjects treated with lovastatin progressed to more advanced Tanner staging and larger testicular volumes at rates not significantly different from those of the placebo group (P=.85 and P=.33 for 24 and 48 weeks, respectively).

Baseline and 4-week hormone values are shown in Table 4. As anticipated, substantial increases in testosterone and LH levels compared with baseline occurred in both treatment groups over 48 weeks, with no significant between-group differences. For DHEAS, the median increase for the lovastatin group was 18% compared with 5% for the placebo group (P=.03).

A number of biochemical measurements to assess nutritional status are shown in Table 5. No differences were found at baseline or after 48 weeks of treatment between groups, except for tocopherol. The reduction of tocopherol (P=.002) with lovastatin is consistent with the decrease in LDL-C, the major transport vehicle for tocopherol in the circulation.

A gradual upward trend from baseline levels in ALT was noted in both placebo and lovastatin groups (Table 6). However, there were no significant differences (P=.20) between groups at week 48, although the increase from baseline for both groups reached statistical significance (lovastatin, P<.001; placebo, P=.008). No consistent changes in AST or CK values were seen. There was no significant difference either from baseline or between the treatment groups in either of these parameters at any of the points. No subject experienced a clinically significant increase in transaminase levels (>3 × the upper limit of normal) or CK level (>10 × the upper limit of normal). There were infrequent, sporadic, and nonsustained CK elevations that exceeded 5 × the upper limit of normal throughout the study, with 3 such occurrences in the lovastatin group and 1 in the placebo group. These were generally associated with vigorous or unusual exercise, and no associated muscle pain was reported. No subject discontinued treatment for biochemical adverse experiences.

One subject taking lovastatin and 2 subjects taking placebo discontinued the study because of adverse clinical experiences. The lovastatin-treated subject reported increased bruising and purpura and the placebo-treated subjects reported skin rash and myalgia. No abnormal results in the hematological indices or basic coagulation testing were found in the lovastatin-treated subject. None of these reasons for discontinuation were considered clinically significant or definitely related to study drug by the investigators. All new or worsening adverse events were recorded and summarized according to organ systems (Table 7). No significant difference between placebo and lovastatin groups was found for observation of any body-system parameter or for clinical adverse events.

Heterozygous FH is a common genetic disorder associated with early death or devastating morbidity due to CAD. Although the homozygous condition unquestionably requires aggressive lipid-lowering therapy, treatment for HeFH is often postponed until later in life. However, as exemplified by the parents of the participants in this study, HeFH is far from benign; 1 in 5 fathers with HeFH were already dead and nearly 3 in 5 had experienced symptoms of CAD. Although the prevalence of CAD was less in mothers with HeFH, almost 1 in 5 had clinical evidence of CAD. Furthermore, the early onset of clinically manifest CAD, sometimes in the 30s age range, highlights the need to treat patients with HeFH, especially boys, early and aggressively. To delay effective lipid-lowering therapy in these high-risk groups until late adolescence or early adulthood can easily result in their being lost to the medical system until they present with CAD or sudden death.

Bile-acid sequestrants have generally been accepted as the drugs of choice in this age group.⁸ However, as was the case with most of the participants prior to their entry into this study, resins are poorly tolerated, are generally ineffective unless taken in large dosages, and result in only a modest LDL-C reduction in patients with severe HeFH.^{9 ,14}

Furthermore, despite their availability for more than 20 years, bile-acid sequestrants have never been evaluated in placebo-controlled trials in children for long periods or in a large number of subjects and have yet to receive FDA approval for lowering cholesterol in children. The longest and largest resin study, by Tonstad et al,³² was only recently published. They studied 72 subjects for 1 year in a randomized placebo-controlled study and concluded that modest LDL-C reductions (17%-19%) were achievable. Although growth was not adversely affected, they noted that folate deficiency may occur and recommended vitamin D supplementation.

Alternative therapy includes nicotinic acid and fibrates. Nicotinic acid has rarely been used in childhood and adolescence^{14 ,33} because it is poorly tolerated and has not been adequately evaluated in terms of long-term safety in this population. Fibric acid derivatives (fenofibrate³⁴ and bezafibrate³⁵ ) have been used in children with HeFH with moderate success in terms of LDL-C reduction. However, these studies have been either uncontrolled or were performed with an inadequate number of subjects to yield meaningful data on safety, including growth and development. Furthermore, both fibrates were associated with significant transaminase elevations in 5% to 25% of pediatric subjects.^{34 - 35}

Of all the systemic agents, statins have been the most widely used and reported in children and adolescents. Early reports in the late 1980s involved small numbers of children with severe HeFH treated in observational or uncontrolled studies.^{14 - 15} However, in the last few years, 2 statin studies in children and adolescents, 1 placebo-controlled and 1 uncontrolled (8-12 weeks), have been reported.^{16 - 17} In a placebo-controlled study with pravastatin sodium,¹⁶ 72 children (66% female) ranging in age from 8 to 16 years were treated with dosages ranging from 5 to 20 mg/d. After 12 weeks, LDL-C reductions ranging from 23% to 32% were obtained. No safety concerns were reported in the 3 months of treatment. Lambert and colleagues¹⁷ recently reported using lovastatin in 69 adolescent boys who were randomized to receive 10 to 40 mg/d for 8 weeks. Low-density lipoprotein cholesterol reductions of 21% to 36% were observed and no safety concerns were reported. However, there was no placebo control. Although both of these studies confirm the efficacy of statins in children, they were both of short duration and inadequate sample size and neither adds significantly to the important issue of safety or the effect on growth and development.

To our knowledge, the present study is the largest and longest placebo-controlled trial of any lipid-lowering drug in an adolescent population. Boys were carefully evaluated at a critical stage in their growth and development, and a number of clinical and biochemical parameters not previously reported in this population were examined. Nevertheless, with approximately 60 patients in each group studied for 48 weeks, there is limited ability to detect adverse effects. Because the prevalence of HeFH is only approximately 0.2%, it is difficult to study large numbers of patients.

The number of subjects who discontinued because of an adverse experience was small. The lack of evidence for symptomatic adverse effects, together with the clinical and biochemical data, supports the tolerability of lovastatin in boys. Although there was no specific evaluation of psychological development or behavior, no adverse effects on mental (eg, school) performance or the central nervous system were reported by the boys or their parents, except for insomnia in 1 patient taking lovastatin. Insomnia with lovastatin has been reported anecdotally in adults by Schaefer.³⁶ However, better-controlled and larger surveys and smaller placebo-controlled sleep laboratory studies have failed to elicit differences from either placebo or other statins or lipid-lowering agents in sleep patterns with lovastatin.^{37 - 38} Muldoon et al³⁹ reported decreased attention and psychomotor speed in adults receiving lovastatin, with the degree of impairment apparently correlating with the amount of LDL-C reduction. However, numerous measurements of cognitive performance were made without adjustment for multiplicity, and other studies in adults with lovastatin or other inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors have found no such effects.^{38 ,40 - 42}

The only significant difference in biochemical measurements between the 2 treatment groups was the reduction in tocopherol observed with lovastatin. This was anticipated and explained by the reduction in LDL-C, which is the major transport vehicle for tocopherol in the circulation. Even with this reduction, tocopherol levels remained well within the accepted reference range.⁴³ Statins are not known to alter tocopherol absorption or transport from the intestine to the liver, which is carried out via chylomicrons and remnants. In fact, it is likely that increased tocopherol delivery to hepatic and other LDL receptor–containing tissue is enhanced by statins, which upregulate receptor activity and facilitate LDL delivery to these cells.

The 2 most common concerns with statins in adults, namely hepatic transaminase elevations and CK increases with myalgia, were not apparent in this study. At no point were there significant between-group differences in these enzyme measurements. There was a trend toward increased ALT over the 48 weeks in both groups, which was slightly accentuated in those taking lovastatin. However, this trend was not significantly different between groups. Increases in ALT during the duration of this trial are not unexpected in adolescent boys because cross-sectional studies reveal a rise in levels in men beginning in adolescence and peaking at about age 35 to 44 years.^{44 - 45} Although the exact reason for the rise is not clear, it may be related to changing hormone levels, obesity, or alcohol use. Aspartate transaminase levels remained stable, as would be expected.⁴⁴ Although many of the boys participated in strenuous exercise and contact sports, no myopathy or sustained CK elevation was noted, and the only withdrawal from the study for myalgia was later found to have been receiving placebo.

The amount of LDL-C reduction achieved is modest in view of the extremely elevated initial levels in these subjects. However, there is evidence in adults that even a 25% decrease in LDL-C will reduce CAD progression in adult FH⁴⁶ and clinical events in subjects without FH and with¹³ or without CAD.^{12 ,47} Furthermore, additional LDL-C reduction may be obtained in these subjects with either larger dosages of lovastatin,¹¹ more efficacious statins,^{48 - 49} or combination therapy with low-dose resins.⁵⁰ In a small uncontrolled study¹⁴ of 4 adolescents with severe HeFH, reductions in LDL-C of 44% were observed with large dosages of statins and resins and moderate dosages of nicotinic acid. However, this is a demanding regimen, and whether more aggressive LDL-C reduction achieved by such combination therapy will have a significant clinical benefit or is cost-effective is uncertain in adults, let alone adolescents.

Although this study is the largest and longest placebo-controlled study in this age group and raised no safety or growth and development concerns, it is still of limited size, and the direct clinical benefit and adverse effects of much longer-term therapy in larger populations is difficult to predict. It also provides no data on adolescent girls. However, in the adolescent male population with severe HeFH similar to that evaluated in this study, there is a substantial risk of CAD within the next 2 decades. The potential benefits of lowering LDL-C levels with statins seems to outweigh the theoretical risks.