Nicotine addiction: Translational insights from circuit neuroscience.

Contemporary neuroscience aims to understand how neuronal activity produces internal processes and observable behavioral states. This aim crucially depends on systems-level, circuit-based analyses of the working brain, as behavioral states arise from information flow and connectivity within and between discrete and overlapping brain regions, forming circuits and networks. Functional magnetic resonance imaging (fMRI), offers a key to advance circuit neuroscience; fMRI measures inter and intra- regional circuits at behaviorally relevant spatial-temporal resolution. Herein, we argue that cross-sectional observations in human populations can be best understood via mechanistic and causal insights derived from brain circuitry obtained from preclinical fMRI models. Using nicotine addiction as an exemplar of a circuit-based substance use disorder, we review fMRI-based observations of a circuit that was first shown to be disrupted among human smokers and was recently replicated in rodent models of nicotine dependence. Next, we discuss circuits that predispose to nicotine dependence severity and their interaction with circuits that change as a result of chronic nicotine administration using a rodent model of dependence. Data from both clinical and preclinical fMRI experiments argue for the utility of fMRI studies in translation and reverse translation of a circuit-based understanding of brain disease states. We conclude by discussing the future of circuit neuroscience and functional neuroimaging as an essential bridge between animal models and human populations to the understanding of brain function in health and disease.

Nicotine dependence (trait) and acute nicotinic stimulation (state) modulate attention but not inhibitory control: converging fMRI evidence from Go-Nogo and Flanker tasks.

Cognitive deficits during nicotine withdrawal may contribute to smoking relapse. However, interacting effects of chronic nicotine dependence and acute nicotine withdrawal on cognitive control are poorly understood. Here we examine the effects of nicotine dependence (trait; smokers (n = 24) vs. non-smoking controls; n = 20) and acute nicotinic stimulation (state; administration of nicotine and varenicline, two FDA-approved smoking cessation aids, during abstinence), on two well-established tests of inhibitory control, the Go-Nogo task and the Flanker task, during fMRI scanning. We compared performance and neural responses between these four pharmacological manipulations in a double-blind, placebo-controlled crossover design. As expected, performance in both tasks was modulated by nicotine dependence, abstinence, and pharmacological manipulation. However, effects were driven entirely by conditions that required less inhibitory control. When demand for inhibitory control was high, abstinent smokers showed no deficits. By contrast, acutely abstinent smokers showed performance deficits in easier conditions and missed more trials. Go-Nogo fMRI results showed decreased inhibition-related neural activity in right anterior insula and right putamen in smokers and decreased dorsal anterior cingulate cortex activity on nicotine across groups. No effects were found on inhibition-related activity during the Flanker task or on error-related activity in either task. Given robust nicotinic effects on physiology and behavioral deficits in attention, we are confident that pharmacological manipulations were effective. Thus findings fit a recent proposal that abstinent smokers show decreased ability to divert cognitive resources at low or intermediate cognitive demand, while performance at high cognitive demand remains relatively unaffected, suggesting a primary attentional deficit during acute abstinence.

Biomarkers for smoking cessation.

One way to enhance therapeutic development is through the identification and development of evaluative tools such as biomarkers. This review focuses on putative diagnostic, pharmacodynamic, and predictive biomarkers for smoking cessation. These types of biomarkers may be used to more accurately diagnose a disease, personalize treatment, identify novel targets for drug discovery, and enhance the efficiency of drug development. Promising biomarkers are presented across a range of approaches including metabolism, genetics, and neuroimaging. A preclinical viewpoint is also offered, as are analytical considerations and a regulatory perspective summarizing a pathway toward biomarker qualification.

A preliminary study suggests that nicotine and prefrontal dopamine affect cortico-striatal areas in smokers with performance feedback.

Nicotine and tonic dopamine (DA) levels [as inferred by catechol-O-methyl tranferase (COMT) Val158Met genotype] interact to affect prefrontal processing. Prefrontal cortical areas are involved in response to performance feedback, which is impaired in smokers. We investigated whether there is a nicotine × COMT genotype interaction in brain circuitry during performance feedback of a reward task. We scanned 23 healthy smokers (10 Val/Val homozygotes, 13 Met allele carriers) during two fMRI sessions while subjects were wearing a nicotine or placebo patch. A significant nicotine × COMT genotype interaction for BOLD signal during performance feedback in cortico-striatal areas was seen. Activation in these areas during the nicotine patch condition was greater in Val/Val homozygotes and reduced in Met allele carriers. During negative performance feedback, the change in activation in error detection areas such as anterior cingulate cortex (ACC)/superior frontal gyrus on nicotine compared to placebo was greater in Val/Val homozygotes compared to Met allele carriers. With transdermal nicotine administration, Val/Val homozygotes showed greater activation with performance feedback in the dorsal striatum, area associated with habitual responding. In response to negative feedback, Val/Val homozygotes had greater activation in error detection areas, including the ACC, suggesting increased sensitivity to loss with nicotine exposure. Although these results are preliminary due to small sample size, they suggest a possible neurobiological mechanism underlying the clinical observation that Val/Val homozygotes, presumably with elevated COMT activity compared to Met allele carriers and therefore reduced prefrontal DA levels, have poorer outcomes with nicotine replacement therapy.

A systematic review and meta-analysis of statin therapy in children with familial hypercholesterolemia.

OBJECTIVE: Functional and morphological changes of the arterial wall already present in young children with heterozygous familial hypercholesterolemia (HeFH) suggest that treatment should be initiated early in life to prevent premature atherosclerotic cardiovascular disease. The purpose of this study was to assess the efficacy and particularly safety of statin therapy in children with HeFH. METHODS AND RESULTS: We performed a meta-analysis of randomized, double-blind, placebo-controlled trials evaluating statin therapy in children aged 8 to 18 years with HeFH. Six studies (n=798 children) with 12 to 104 weeks of treatment were included. Total cholesterol, LDL cholesterol, and apolipoprotein B were significantly reduced, whereas HDL cholesterol and apolipoprotein A1 were significantly increased by statin therapy. No statistically significant differences were found between statin- and placebo-treated children with respect to the occurrence of adverse events (RR 0.99; 95% CI: 0.79 to 1.25), sexual development (RR of advancing > or = 1 stage in Tanner classification 0.96; 95% CI: 0.79 to 1.17), muscle toxicity (RR of CK > or = 10 times the upper limit of normal [ULN] 1.38; 95% CI: 0.18 to 10.82), or liver toxicity (RR of > or = 3 times the ULN for ASAT 0.98; 95% CI: 0.23 to 4.26 and for ALAT 2.03; 95% CI: 0.24 to 16.95). We found a minimal difference in growth in favor of the statin group (0.33 cm; 95% CI: 0.03 cm to 0.63 cm). CONCLUSION: In addition to the fact that statin treatment is efficacious, our results support the notion that statin treatment in children with HeFH is safe. Thus, even though further studies are required to assess lifelong safety, statin treatment should be considered for all children aged 8 to 18 with HeFH.

Fluvastatin treatment is not associated with an increased incidence of cancer.

Concerns regarding a potential link between statin treatment and increased risk of cancer were raised following the increased cancer incidence observed in patients treated with pravastatin in the Cholesterol and Recurrent Events and Pravastatin in Elderly Individuals at Risk of Vascular Disease studies. The aim of the present study was to investigate the risk of cancer associated with fluvastatin treatment in clinical trials. A pooled analysis of all available, randomised, placebo-controlled trials with fluvastatin with a minimum treatment period of 24 weeks was performed. The cancer incidences were compared in 3512 patients receiving fluvastatin, 20-80 mg/day, and 3289 patients receiving placebo. Overall, fewer patients were diagnosed with cancer in the fluvastatin group compared with the placebo group [220/3512 (6.3%) vs. 263/3289 (8.0%) respectively; p = 0.0309]. Cox regression analysis, adjusted for baseline covariates and stratified by study, revealed a hazard ratio for first cancer diagnosis of 0.812 [95% confidence interval (CI) 0.667-0.989; p = 0.037] for fluvastatin compared with placebo. No significant differences were observed in the incidence of cancers by site, with the exception of non-melanoma skin cancer (103 vs. 125 cases in the fluvastatin and placebo groups respectively; p = 0.047). Cox regression analysis showed that there was no association between baseline low-density lipoprotein cholesterol levels and the risk of developing cancer (hazard ratio 0.998, 95% CI 0.995-1.000; p = 0.107). In conclusion, fluvastatin treatment is not associated with an increased risk of cancer compared with placebo in clinical trials, independent of patient age, treatment duration and baseline cholesterol levels.

fMRI: a new tool for the in vivo localization of drug actions in the brain.

Functional magnetic resonance imaging (fMRI), a still-emerging, non-invasive neuroimaging tool, has been applied to a wide range of questions in sensory, motor control, and cognitive psychology. Only more recently has it been applied to understand the sites and mechanisms of action of pharmacological agents within the human CNS. However, in so doing, a new set of problems and concerns surrounding the technique must be addressed because of the unique transduction mechanisms (both physiological and biophysical) that exist to produce the fMRI signal from the underlying neuronal activity. Experimental design and control issues become paramount in performing fMRI pharmacological protocols and in signal interpretation. With these caveats, the use of pharmacological agents with fMRI is likely to greatly increase in the near term as new questions about both brain physiology and neuropharmacological mechanisms become addressable for the first time. Examples are given using nicotine and cocaine as a prototypical agents.

Effects of statins on biomarkers of bone metabolism: a randomised trial.

BACKGROUND AND AIM: Recently, several studies have indicated there may be differences among statins regarding a possible association between therapy and a reduction in risk of fractures. No data from prospective randomised clinical trials designed to assess either biochemical or clinical effects on bone metabolism are yet available. We assayed levels of biochemical markers of bone formation in stored serum samples from a recently completed randomised clinical trial conducted to compare the effects of simvastatin and atorvastatin on the lipid profile of patients with hypercholesterolaemia. METHODS AND RESULTS: This 12-week, randomised, multicenter, open-label study was designed to compare the safety and lipid-lowering efficacy of simvastatin 40 mg or 80 mg with that of atorvastatin 20 mg or 40 mg in 846 hypercholesterolaemic patients. Stored serum samples from this study were analysed to compare the effects of simvastatin and atorvastatin on 2 biomarkers of bone turnover, bone-specific alkaline phosphatase (BSAP), a marker of bone formation, and C-teleopeptide of type 1 collagen (CTx), a marker of bone resorption. Treatment with simvastatin 40 and 80 mg/day, but not atorvastatin 20 and 40 mg/day, led to significant (p < 0.05) reductions in BSAP in both men (4.1-5.4% reduction) and women (4.2-7.4% reduction). In addition, there appeared to be a dose-dependent effect with greater reductions in BSAP seen with the 80 mg dose of simvastatin. Treatment with either 20 mg or 40 mg of atorvastatin had no significant effect on BSAP levels on the groups as a whole or in the gender-specific subgroups. CTx showed a small, but not statistically significant, decrease with simvastatin, again with an apparent dose-related trend. Atorvastatin treatment generally resulted in small, non significant increases in CTx. CONCLUSIONS: The present serum bone biomarker results show that treatment with simvastatin, but not atorvastatin, decreases BSAP and suggest that simvastatin may have a beneficial effect on bone turnover.

Statins in children. Why and when.

There is now ample evidence to demonstrate that atherosclerosis begins in childhood and is significantly accelerated in certain genetic disorders, most notably familial hypercholesterolemia (FH). Untreated FH, both the homozygous and heterozygous forms, carry a substantial burden of morbidity and mortality if left untreated or inadequately treated. Males with FH are at earlier and greater risk than females and thus should begin therapy earlier, preferably at about 10. While bile acid sequestrants have long been considered the drug of choice in children, they have never been approved for pediatric use by FDA, are poorly tolerated, marginally effective at lowering low-density lipoprotein cholesterol and have minimal well controlled studies in children upon which to adequately assess safety. Over the last decade statins have been studied extensively in children and adolescents, although many of these studies have also been poorly controlled, of short duration, too small and lack detailed assessment. However there has been at least one large, randomized, placebo-controlled and comprehensive study with lovastatin in adolescent males that indicated efficacy similar to that anticipated in adults and no apparent safety concerns. While additional well-controlled studies are needed, especially those focusing on surrogates of atherosclerosis to determine clinical benefit, it is opportune for re-evaluation of current treatment guidelines.

Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS): efficacy and tolerability of long-term treatment with lovastatin in women.

The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) is the first coronary heart disease (CHD) primary prevention trial of the cholesterol-reducing agents called "statins" to include women. For 5608 men and 997 postmenopausal women without clinical evidence of cardiovascular disease (CVD) who had average low-density lipoprotein cholesterol (LDL-C) and below average high-density lipoprotein cholesterol (HDL-C), 20-40 mg/day lovastatin reduced first acute major coronary events (AMCEs) 37% (for those receiving placebo and lovastatin, respectively, 183 and 116 first AMCEs defined as fatal or nonfatal myocardial infarction [MI], unstable angina, or sudden cardiac death; relative risk [RR] 0.63; 95% confidence interval [95% CI] 0.50, 0.79; p < 0.001). Statistically significant reductions in prespecified secondary end points (coronary revascularizations, unstable angina, MI, cardiovascular end point events, and coronary end point events) were also associated with lovastatin treatment in the overall cohort. This paper provides results in women, a prespecified subgroup. Among women, 20-40 mg/day lovastatin reduced LDL-C 25% and increased HDLC 9% (p < 0.001). A prespecified analysis revealed consistency with the overall results regardless of gender (i.e., there were no statistical differences between men and women in risk reduction for first AMCEs with lovastatin). However, the number of women who had an AMCE was small, and there was insufficient power to detect a treatment group difference among women (7 of 499 vs. 13 of 498 first AMCEs in those receiving lovastatin and placebo, respectively; RR 0.54; 95% CI 0.22, 1.35; p = 0.183). Numerical reductions in all prespecified secondary end points were observed for women treated with lovastatin, but again, the numbers of events were small and the differences were not statistically significant. Chronic long-term treatment with lovastatin was well tolerated, with no treatment group differences in the frequency of cancer, muscle symptoms, and clinically important liver enzyme elevations. In AFCAPS/TexCAPS, a consistent pattern of numerical reductions in all prespecified primary and secondary cardiovascular end points was observed in women treated with lovastatin for primary prevention of CHD. However, because of the small number of events, there was insufficient power to detect significant treatment group differences. Lovastatin treatment was associated with statistically significant decreases in LDL-C and increases in HDL-C, and chronic long-term treatment with 20-40 mg/day lovastatin was well tolerated in women.

Cue-induced cocaine craving: neuroanatomical specificity for drug users and drug stimuli.

OBJECTIVE: Cocaine-related cues have been hypothesized to perpetuate drug abuse by inducing a craving response that prompts drug-seeking behavior. However, the mechanisms, underlying neuroanatomy, and specificity of this neuroanatomy are not yet fully understood. METHOD: To address these issues, experienced cocaine users (N=17) and comparison subjects (N=14) underwent functional magnetic resonance imaging while viewing three separate films that portrayed 1 ) individuals smoking crack cocaine, 2) outdoor nature scenes, and 3) explicit sexual content. Candidate craving sites were identified as those that showed significant activation in the cocaine users when viewing the cocaine film. These sites were then required to show significantly greater activation when contrasted with comparison subjects viewing the cocaine film (population specificity) and cocaine users viewing the nature film (content specificity). RESULTS: Brain regions that satisfied these criteria were largely left lateralized and included the frontal lobe (medial and middle frontal gyri, bilateral inferior frontal gyrus), parietal lobe (bilateral inferior parietal lobule), insula, and limbic lobe (anterior and posterior cingulate gyrus). Of the 13 regions identified as putative craving sites, just three (anterior cingulate, right inferior parietal lobule, and the caudate/lateral dorsal nucleus) showed significantly greater activation during the cocaine film than during the sex film in the cocaine users, which suggests that cocaine cues activated similar neuroanatomical substrates as naturally evocative stimuli in the cocaine users. Finally, contrary to the effects of the cocaine film, cocaine users showed a smaller response than the comparison subjects to the sex film. CONCLUSIONS: These data suggest that cocaine craving is not associated with a dedicated and unique neuroanatomical circuitry; instead, unique to the cocaine user is the ability of learned, drug-related cues to produce brain activation comparable to that seen with nondrug evocative stimuli in healthy comparison subjects.

Hepatitis C virus infection in cocaine users--a silent epidemic.

Over a recent three year period, approximately 600 individuals responded to newspaper advertisements for research studies requiring healthy, cocaine using subjects. These subjects were screened using a standard phone interview in order to eliminate individuals with known medical or psychiatric illnesses that would exclude them from ongoing neuroimaging studies of drug abuse. Individuals were specifically asked about their hepatitis and HIV status. Of these, 170 subjects passed the phone screen, having no known medical or psychiatric illness outside of cocaine abuse/dependence and were willing to be further evaluated for the studies. These subjects were brought to the Medical College of Wisconsin's General Clinical Research Center and tested for, among other measures, hepatitis B, hepatitis C, and HIV. Of these, 144 completed the examination and all testing. In this cohort of assumed healthy subjects, 47 (33%) tested positive for antibodies to the hepatitis C virus (HCV). Only 7 (5%) tested positive for the hepatitis B surface antigen and 2 (1.4%) to HIV. The demographics of this cohort are 56% African-American, 81% male, 75% never-married, 55% unemployed with a mean age of 36 years. The percentage of subjects reporting any lifetime intravenous drug use among the HCV(+) and the HCV(-) cohorts was 77% vs. 29% respectively. Some routes of HCV transmission are still unclear and may reflect lifestyle or other factors related to cocaine use outside of parenteral drug use. Since almost all HCV infections become chronic, and many progress to chronic active hepatitis, cirrhosis, and ultimately hepatocellular carcinoma, these observations suggest a significant epidemic in an unsuspecting population with little regular access to health care. These individuals also form a large pool for the continued transmission of HCV to the general population. Additional public health interventions are suggested.

Heroin-induced neuronal activation in rat brain assessed by functional MRI.

The present study demonstrates the application of fMRI technology to neuropharmacology and the interaction of drug/receptor in the rat brain. Specifically, we have observed two different types of fMRI signal changes induced by acute i.v. heroin administration in rat brains under conditions of spontaneous and artificial respiration. Under spontaneous respiration, a global decrease in fMRI signal was observed; under artificial respiration, a region-specific increase in fMRI signal was identified and the activation sites are consistent with the distribution of opiate mu-receptors in rat brain as previously reported by autoradiography. Both heroin-induced fMRI signal changes were suppressed by pretreatment of naloxone, an opiate mu-receptor antagonist, and reversed by injection of naloxone following heroin infusion. These results suggest that fMRI has specific advantages in spatial and temporal resolution for studies of neuropharmacology and drugs of abuse.

Efficacy and safety of lovastatin in adolescent males with heterozygous familial hypercholesterolemia: a randomized controlled trial.

CONTEXT: Heterozygous familial hypercholesterolemia (HeFH) is a common disorder associated with early coronary artery disease, especially in men. The age at which drug therapy should be started is still controversial, as is the use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). OBJECTIVE: To assess the lipid-lowering efficacy, biochemical safety, and effect on growth and sexual development of lovastatin in adolescent boys with HeFH. DESIGN: One-year, double-blind, placebo-controlled, balanced, 2-period, 2-arm randomized trial. In the first period (24 weeks), lovastatin was increased at 8 and 16 weeks and the dosage remained stable during the second period (24 weeks). The study was conducted between 1990 and 1994. SETTING: Fourteen pediatric outpatient clinics in the United States and Finland. PATIENTS: Boys aged 10 to 17 years with HeFH. Of 132 randomized subjects (67 intervention, 65 placebo), 122 (63 intervention, 59 placebo) and 110 (61 intervention, 49 placebo) completed the first and second periods, respectively. INTERVENTION: Lovastatin, starting at 10 mg/d, with a forced titration at 8 and 16 weeks to 20 and 40 mg/d, respectively, or placebo. MAIN OUTCOME MEASURES: The primary efficacy outcome measure was low-density lipoprotein cholesterol (LDL-C). Primary safety measures were growth and sexual development. RESULTS: Compared with placebo, LDL-C levels of patients receiving lovastatin decreased significantly (P<.001) by 17%, 24%, and 27% receiving dosages of 10, 20, and 40 mg/d, respectively, and remained 25 % lower than baseline at 48 weeks. Growth and sexual maturation assessed by Tanner staging and testicular volume were not significantly different between the lovastatin and placebo groups at 24 weeks (P = .85) and 48 weeks (P = .33); neither were serum hormone levels or biochemical parameters of nutrition. However, the study was underpowered to detect significant differences in safety parameters. Serum vitamin E levels were reduced with lovastatin treatment consistent with reductions in LDL-C, the major carrier of vitamin E in the circulation. CONCLUSIONS: This study in adolescent boys with HeFH confirmed the LDL-C-reducing effectiveness of lovastatin. Comprehensive clinical and biochemical data on growth, hormonal, and nutritional status indicated no significant differences between lovastatin and placebo over 48 weeks, although further study is required.

Determination of drug-induced changes in functional MRI signal using a pharmacokinetic model.

As the applications of functional magnetic resonance imaging (fMRI) expand, there is a need for the development of new strategies for data extraction and analysis that do not require the presentation of stimuli in a repeated on/off pattern. A description and evaluation of a method and computer algorithm for the detection and analysis of brain activation patterns following acute drug administration using fMRI are presented. A waveform analysis protocol (WAP) input function has been developed that is based upon the single-dose pharmacokinetics of a drug of interest. As a result of this analysis, regional brain activation can be characterized by its localization and intensity of activation, onset of action, time to peak effect, and duration of action. A global statistical test for significant drug effects based upon the probability of a voxel being activated by a saline vehicle injection is applied to grouped data on a voxel by voxel basis. Representative data are presented using nicotine as a prototypical agent. Using this method, statistically significant drug-induced brain activation has been identified in several key cortical and subcortical brain regions.

Nicotine-induced limbic cortical activation in the human brain: a functional MRI study.

OBJECTIVE: Nicotine is a highly addictive substance, and cigarette smoking is a major cause of premature death among humans. Little is known about the neuropharmacology and sites of action of nicotine in the human brain. Such knowledge might help in the development of new behavioral and pharmacological therapies to aid in treating nicotine dependence and to improve smoking cessation success rates. METHOD: Functional magnetic resonance imaging, a real-time imaging technique, was used to determine the acute CNS effects of intravenous nicotine in 16 active cigarette smokers. An injection of saline followed by injections of three doses of nicotine (0.75, 1.50, and 2.25 mg/70 kg of weight) were each administered intravenously over 1-minute periods in an ascending, cumulative-dosing paradigm while whole brain gradient-echo, echo-planar images were acquired every 6 seconds during consecutive 20-minute trials. RESULTS: Nicotine induced a dose-dependent increase in several behavioral parameters, including feelings of "rush" and "high" and drug liking. Nicotine also induced a dose-dependent increase in neuronal activity in a distributed system of brain regions, including the nucleus accumbens, amygdala, cingulate, and frontal lobes. Activation in these structures is consistent with nicotine's behavior-arousing and behavior-reinforcing properties in humans. CONCLUSIONS: The identified brain regions have been previously shown to participate in the reinforcing, mood-elevating, and cognitive properties of other abused drugs such as cocaine, amphetamine, and opiates, suggesting that nicotine acts similarly in the human brain to produce its reinforcing and dependence properties.

Long-term effects of low-density lipoprotein apheresis using an automated dextran sulfate cellulose adsorption system. Liposorber Study Group.

The short-term effectiveness of low-density lipoprotein (LDL) apheresis using a dextran sulfate cellulose adsorption column technique was previously examined in a 9-center, 22-week controlled trial in 64 patients with familial hypercholesterolemia (FH) who did not adequately respond to diet and drug therapy. Forty-nine patients (40 treatment, 9 controls) subsequently received LDL apheresis procedures as part of an optional follow-up phase. This study reports on the long-term safety, lipid lowering, and clinical efficacy of LDL apheresis for the 5-year period that includes both the initial controlled study and follow-up phase. During this time, patients received a total of 3,902 treatments of which 3,314 treatments were given during the follow-up phase. Adverse events were infrequent, occurring in 142 procedures (3.6%). Immediate reduction in LDL cholesterol was 76% both in homozygotes and in heterozygotes. Patients with homozygous FH had a progressive decrease in pretreatment LDL cholesterol level along with an increase in high-density lipoprotein (HDL) cholesterol level. There was no appreciable change in pretreatment lipoprotein level over time in heterozygotes. The rate of cardiovascular events during therapy with LDL apheresis and lipid-lowering drugs was 3.5 events per 1,000 patient-months of treatment compared with 6.3 events per 1,000 patient-months for the 5 years before LDL apheresis therapy. These findings support the long-term safety and clinical efficacy of LDL apheresis in patients with heterozygous and homozygous FH who are inadequately controlled with drug therapy.

Expanded-dose simvastatin is effective in homozygous familial hypercholesterolaemia.

Patients with homozygous familial hypercholesterolaemia (HFH) have abnormalities in both low-density lipoprotein (LDL) receptor alleles, resulting in severe hypercholesterolaemia and premature coronary heart disease. Limited treatment options are available and the response to drug therapy has been poor. In the present paper, we have evaluated the efficacy and safety of simvastatin at doses beyond the current maximal dose of 40 mg/day in patients with HFH. After a 4 week placebo diet run-in period, 12 patients with well-characterized HFH were randomized to simvastatin 80 mg/day administered in three divided doses (n = 8; group 1) or 40 mg once daily (n = 4; group 2). After 9 weeks, the dose in group 1 was increased to 160 mg/day while the dose in group 2 was kept at 40 mg/day, but with the drug given in three divided doses and treatment continued for an additional 9 weeks. All 12 patients completed the study and there were no serious or unexpected adverse effects. LDL-cholesterol concentrations fell by 14% at the 40 mg/day dose, but were reduced further at the higher doses (25% at the 80 mg/day and by 31% at the 160 mg/day dosage, P < 0.0001). Excretion of urinary mevalonic acid, as an index of in vivo cholesterol biosynthesis, was reduced but did not correlate with reduction in LDL-cholesterol in the individual patients. The magnitude of response to therapy was not predicted by the LDL-receptor gene defect as patients with the same LDL-receptor mutations responded differently to the same dose of simvastatin therapy. The ability of expanded doses of simvastatin (80 or 160 mg/day) to reduce LDL-cholesterol levels in patients with HFH, even if receptor negative, suggests that at these doses, the drug reduces LDL production. Simvastatin therapy, at doses of 80 or 160 mg/day, should therefore be considered in all patients with HFH, either as an adjunct to apheresis, or as monotherapy for those patients who do not have access to apheresis or other such treatment modalities.

A pilot study of ex vivo gene therapy for homozygous familial hypercholesterolaemia.

The outcome of the first pilot study of liver-directed gene therapy is reported here. Five patients with homozygous familial hypercholesterolaemia (FH) ranging in age from 7 to 41 years were enrolled; each patient tolerated the procedure well without significant complications. Transgene expression was detected in a limited number of hepatocytes of liver tissue harvested four months after gene transfer from all five patients. Significant and prolonged reductions in low density lipoprotein (LDL) cholesterol were demonstrated in three of five patients; in vivo LDL catabolism was increased 53% following gene therapy in a receptor negative patient, who realized a reduction in serum LDL equal to approximately 150 mg dl-1. This study demonstrates the feasibility of engrafting limited numbers of retrovirus-transduced hepatocytes without morbidity and achieving persistent gene expression lasting at least four months after gene therapy. The variable metabolic responses observed following low-level genetic reconstitution in the five patients studied precludes a broader application of liver-directed gene therapy without modifications that consistently effect substantially greater gene transfer.

Successful ex vivo gene therapy directed to liver in a patient with familial hypercholesterolaemia.

An ex vivo approach to gene therapy for familial hypercholesterolaemia (FH) has been developed in which the recipient is transplanted with autologous hepatocytes that are genetically corrected with recombinant retroviruses carrying the LDL receptor. We describe the treatment of a 29 year old woman with homozygous FH by ex vivo gene therapy directed to liver. She tolerated the procedures well and in situ hybridization of liver tissue four months after therapy revealed evidence for engraftment of transgene expressing cells. The patient's LDL/HDL ratio declined from 10-13 before gene therapy to 5-8 following gene therapy, improvements which have remained stable for the duration of the treatment (18 months). This represents the first report of human gene therapy in which stable correction of a therapeutic endpoint has been achieved.