Category Archives: drug safety
LDL-Lowering Genetic Variants Linked to Increased Risk of Diabetes
–What can genetic studies tell us about the risk of developing diabetes with cholesterol-lowering therapies?
This post was first published on MedPageToday and CardioBrief.org.
In a study published in the Journal of the American Medical Association, several LDL-lowering genetic variants were found to be associated with a reduced risk of coronary artery disease and an increased risk of type 2 diabetes. The study investigated LDL-lowering alleles in or near Niemann-Pick C1-Like 1 (NPC1L1), HMG-CoA reductase (HMGCR), PCSK9, ABCG5/G8, and low density lipoprotein receptor (LDLR). NPC1L1 is the target of ezetimibe, while HMGCR is the target of statins and PCSK9 is the target of PCSK9 inhibitors.
Luca Lotta, of the University of Cambridge, and colleagues conducted meta-analyses of genetic association studies, and included 50,775 individuals with type 2 diabetes and 270,269 controls and 60,801 individuals with CAD and 123,504 controls.
The study found that for a 38.7 mg/dL reduction in LDL-cholesterol, the genetic variants were associated with a similar reduction in risk of coronary artery disease, with odds ratios ranging from 0.54 to 0.62. However, genetic variants at the NPC1L1 locus were associated with a higher risk of diabetes (odds ratio 2.42) as compared to controls than the HMGCR and PCSK9 genetic variants (odd ratios of 1.39 and 1.19, respectively). The type 2 diabetes findings for NPC1L1 and HMGCR were highly significant (p = 9 x 107 and p = .003, respectively), but the p value for the type 2 diabetes finding for the PCSK9 variants was .03. The associations with type 2 diabetes for ABCG5/G8 and LDLR were not significant.
Treatment with statins is known to be associated with a higher incidence of new-onset diabetes, as is treatment with niacin, but the effect of ezetimibe and PCSK9 inhibitors on new-onset diabetes is unclear. An analysis of the IMPROVE-IT trial showed a small increase in new-onset diabetes in the ezetimibe group, but the difference was not statistically significant. The published data for the PCSK9 inhibitors have not shown statistically significant increases in blood sugar or new-onset diabetes (see here and here), but much more data will be available when the PCSK9 inhibitor outcomes trials are completed, starting next year.
One reason to wonder why PCSK9 inhibitors might increase blood sugar is that both statins and PCSK9 inhibitors have mechanisms of action that involve the removal of LDL from the bloodstream through upregulation of the LDL receptors. A recent study showed that patients with familial hypercholesterolemia, a disease that involves dysfunction of the LDL receptors, have a lower prevalence of type 2 diabetes as compared to their unaffected relatives. The study suggests that LDL receptor function may be involved in glucose homeostasis. I asked several experts in clinical trials or cardiovascular genetics to comment by email.
Sanjay Kaul, MD, of Cedars Sinai Medical Center in Los Angeles, sent the following comment by email:
The association of LDL-lowering alleles with CV risk is consistent across the 5 alleles. However, the association of LDL-lowering alleles with risk of T2DM is confined to NPC1L1 (large effect size, HR 2.4 and statistically robust p value) and to a lesser extent to HMGCR (HR 1.4, p = 0.003). This finding suggests an increased risk of incident diabetes with ezetimibe that targets NPC1L1. However, the incidence of new onset DM (defined as initiation of anti-diabetic medication during trial or two consecutive fasting glucose ≥126 mg/dL) in IMPROVE-IT trial was 720/5297 (13.6%) in EZ/SV vs. 694/5341 (13.0%) in SV, HR 1.04 95% CI (0.94, 1.15). The additional LDL lowering with ezetimibe was approximately 16 mg/dL which translates into a HR of 1.10 per mmol/L LDL lowering (1.04/16) x 38.7). This is considerably lower than the HR of 2.4 observed in the gene association study. Of course the median exposure in IMPROVE-IT was only 7 years when about 42% of subjects had discontinued treatment compared with the lifetime exposure in the gene association study. One would need a larger data set (meta-analysis of SHARP, SEAS, IMPROVE-IT, ARBITER-6, etc.) to better characterize the risk of incident T2DM. Even if we assume the association to be causal, remember the treatment effect in IMPROVE-IT was exclusively confined to the diabetic cohort who comprised 27% of the overall cohort (HR 0.86, 95% CI 0.78, 0.84 vs HR 0.98 for the non-diabetic cohort).
Joshua Knowles, MD, PhD, of Stanford University in California, sent the following comment:
This is an important paper by a very good group of investigators. The overall results of this Mendelian randomization study are not that surprising but are still very important, that there is an inverse relationship between LDL-C lowering genetic alleles and risk of type 2 diabetes.
There has been a lot of evidence emerging about this from the large statin trials to studies of [familial hypercholesterolemia (FH)] patients to prior Mendelian randomization studies.
The fact that they observe some heterogeneity of effect is interesting in that it might suggest that different ways of lowering LDL-C might result in different levels of risk for type 2 diabetes.
The overall effect they see for NPC1L1 genetic variants (a risk of 2.42 for type 2 diabetes for every 1 mmol/L reduction in LDL-C) suggests that this mechanism might theoretically be more potent for causing T2D risk.
However, in practice, ezetimibe does not lower LDL-C by 1 mmol/l but more like by ~0.5 mmol/L (or even less) so the actual effect size in ezetimibe trials (like IMPROVE-IT) will be less than 2.4 (probably more like 1.2). And in IMPROVE IT the effects might be masked to some extent as everyone was also on a statin and we don’t know if the effects would be additive.
The large scale PCKS9 trials will be revealing for their risk. Certainly these studies do not suggest that there will be a big effect which is good for the patients taking them now.
Please emphasize that overall message remains that for high risk patients (like FH) the beneficial effect of LDL-C lowering will greatly trump the increased risk of type 2 diabetes.
What is fascinating for me is we really have no idea whether the increased T2D risk is because the drugs decrease insulin secretion or increase insulin resistance. Knowing this will be critically important.
I am very interested in this topic and have a Doris Duke Clinical Investigator Grant to study it in a randomized trial. We will be measuring (with gold standard measures) insulin secretion and insulin resistance pre and post statin.
Remember that T2D is simply defined as an increase in blood glucose. These drugs seem to mostly push people that are ALMOST diabetic just over the threshold (see our recent paper published in the American Journal of Cardiology). Simply having an average blood glucose level go from 123 mg/dl to 127 mg/dl probably is not that important to a single person’s individual risk of downstream bad outcomes (though that person would go from being a pre-diabetic to a diabetic with that small change in blood glucose). What may be more important is HOW and WHY that blood glucose level rose. If there is not enough insulin being made, the treatment would potentially be different than if the body is not responding to insulin.
Another key message is to reemphasize the importance of exercise and maintenance of a healthy weight to potentially counteract the effect of these LDL-C lowering drugs on T2D. We should continue to advocate those important lifestyle choices for our patients. If you look at the data in [our paper] the risk of T2D with a statin is EXTREMELY low (3%) in those with normal fasting glucose and normal triglycerides (or weight) but very high in patients with pre-diabetes and high triglycerides (or overweight)– 23%!
I also received this comment from Daniel Swerdlow, MBBS, PhD, of Imperial College London:
This is a well-designed analysis that uses methods that are now established for using genetics to explore the effects of drug target modulation. The associations of the variants in NPC1L1 and PCSK9 on type 2 diabetes risk are not unexpected, as it appears from other large genetic analyses published recently that LDL-C lowering associates with higher diabetes risk, regardless of the mechanism through which this is achieved. This has been borne out in trials of statins and niacin, though the IMPROVE-IT trial of ezetimibe did not demonstrate an increased risk of diabetes in the treatment arm. The effect sizes in studies such as this are less informative than the direction of the effect, since direct comparison of the magnitudes of genetic effects and drug treatments is restricted by the differences in duration and potency of the two ‘interventions’. The biological analogy, however, allows the directions and scope of genetic associations to be interpreted as proxies for drug effects on the target encoded by the gene in question. The issue of new onset diabetes risk is pertinent for the PCSK9 inhibitors, and although analyses of trial data to-date has shown no association, they have been limited by duration of follow-up and sample size. The large phase 3 outcome trials are expected to focus carefully on diabetes risk with these new agents.
The over-riding message that analyses such as this in JAMA emphasize is that lipid-modifying treatments are only one part of cardiovascular risk reduction, and must be accompanied by lifestyle modification, such as appropriate diet and higher physical activity, in order to optimize risk reduction and mitigate against the small increase in diabetes risk that has been shown to be associated with some lipid-modifying drug treatments.
More data on alirocumab and diabetes risk
I happened to see an abstract from the American Heart Association Scientific Sessions in which the authors slice and dice the alirocumab data to see if they could find effects on development of diabetes or impaired glucose control in patients without diabetes at baseline. As you can see in the table below, there are some numerical differences in (1) patients with normal blood sugar at baseline who developed impaired glucose control and (2) patients with impaired glucose control who developed diabetes. The differences were not statistically significant. No resolution of this issue is likely until the results of the outcomes trials are available. See my previous post on this here.
2013 Gina Kolata article on PKSK9 inhibitors was inaccurate
A 2013 front page New York Times article by Gina Kolata on PCSK9 inhibitors was inaccurate. Here is Kolata’ lede:
She was a 32-year-old aerobics instructor from a Dallas suburb — healthy, college educated, with two young children. Nothing out of the ordinary, except one thing.
Her cholesterol was astoundingly low. Her low-density lipoprotein, or LDL, the form that promotes heart disease, was 14, a level unheard-of in healthy adults, whose normal level is over 100.
The reason was a rare gene mutation she had inherited from both her mother and her father. Only one other person, a young, healthy Zimbabwean woman whose LDL cholesterol was 15, has ever been found with the same double dose of the mutation.
Here is an excerpt from the FDA clinical review of Sanofi/Regeneron’s PCSK9 inhibitor alirocumab:
We are aware of three cases of individuals homozygous (or compound heterozygous) for loss-of-function PCSK9 alleles with very low LDL-C concentrations that have been reported in the literature:
1. a 21-year-old African woman with an LDL-C of 15 mg/dL; no further information about this patient was provided, except that she was identified for genotyping at a postnatal clinic,
2. a 32-year-old African American woman with an LDL-C of 14 mg/dL; she is an apparently healthy, normotensive, fertile, college-educated individual with normal liver and renal function tests, and
3. a 49-year-old French white man who was found to have extremely low LDL-C (7 mg/dL) on admission for rapid-onset of an insulin-requiring diabetes mellitus of unknown etiology; LDL-C not during acute illness was reported to be 16 mg/dL. This patient was shown to have moderate liver steatosis on abdominal ultrasound with normal hepatic enzymes and liver function tests. He had no reported history of diarrhea, eye, or neurological abnormalities related to any vitamin deficiency. His mother was deceased at age 66 from dementia, whereas his father was healthy at age 79. His grandparents died at the ages of 79, 87, 91, and 94 years.
At this time there are too few cases to provide conclusive data about loss-of-function PCSK9 polymorphisms and the risk of human disease, although given the association of statins with diabetes risk, the development of diabetes in the 49-year-old man discussed above is of interest. (See Dr. Roberts’ safety review for further discussion of alirocumab and glycemic parameters).
The third case is the one missed by Kolata. It was published in Arteriosclerosis, Thrombosis, and Vascular Biology, an American Heart Association journal, in 2009, and could have been found with a PubMed search. The case is interesting in that it conflicts with one of the oft-repeated but inaccurate narratives with respect to PCSK9 inhibitors, the idea that all known persons with extremely low LDL due to having two PCSK9 loss-of-function mutations are completely healthy. I agree with the FDA reviewer that there are too few such cases to provide conclusive data about loss-of-function PCSK9 polymorphisms that result in extremely low LDL levels and the risk of disease. (The issue of whether alirocumab increases blood glucose and the risk of developing diabetes is also discussed extensively in the review, with the reviewer concluding that the evidence is inconclusive at this point.)
Do PCSK9 inhibitors affect diabetes risk?
Two PCSK9 inhibitors, evolocumab and alirocumab, are under consideration at the FDA and will be the subject of advisory committee meetings on June 9 and 10. Evolocumab and alirocumab are monoclonal antibodies that inhibit proprotein convertase subtilisin/kexin type 9 (PCSK9), an enzyme that plays a role in regulating levels of LDL cholesterol by binding to LDL receptors and promoting their degradation; the resulting reduction in LDL receptors reduces the liver’s ability to remove circulating LDL. PCSK9 inhibitors prevent PCSK9 from degrading LDL receptors; the increased LDL receptor density results in increased clearance of LDL from the bloodstream. The expectation is that lower LDL levels in patients who receive PCSK9 inhibitors will result in a reduction in cardiovascular events and this strategy is currently being tested in large outcomes trials, which will be completed in a few years. Until those trials are completed, the safety and efficacy of these drugs will not be known.
One of the unknowns with PCSK9 inhibitors is their effect (if any) on blood glucose levels and the development of new-onset diabetes. Statins are known to increase the risk of new-onset diabetes by about 9% overall, with increased risk from intensive vs. moderate intensity statin therapy. One reason to wonder whether PCSK9 inhibitors might have a similar effect is that both statins and PCSK9 inhibitors, though having different mechanisms of action, both involve the removal of LDL through upregulation of LDL receptors. The reason statins increase blood glucose is unknown, but recently it has been suggested that that the LDL receptor might be involved, with greater LDL receptor activity correlating with a higher risk of diabetes. A recent study showed that patients with familial hypercholesterolemia (FH) in the Dutch FH registry have a lower prevalence of type 2 diabetes as compared to their unaffected relatives. FH is a genetic disease in which the LDL receptor function is reduced, leading to higher serum levels of LDL cholesterol. In addition, the study found a dose-response relationship, with more severe FH mutations linked to lower risk of diabetes as compared to less severe mutations. In other words, the study showed an association between less functional LDL receptors and a lower prevalence of type 2 diabetes. In an editorial, David Preiss and Naveed Sattar note that the study suggests that “the expression and function of LDL receptors may be important for glucose homeostasis” and that the advent of PCSK9 inhibitors provides an opportunity to further examine a possible link between LDL receptor expression and glycemia and diabetes risk.
I’ve looked at some of the published data on PCSK9 inhibitors and blood glucose and diabetes risk. With respect to alirocumab, I abstracted a subset of the data in an abstract presented at the March 2015 American College of Cardiology conference.
As you can see, the data show small numerical increases in new-onset diabetes and worsening of preexisting diabetes, as well as larger increases in fasting glucose and hemoglobin A1c over the course of a year in patients on alirocumab as compared to patients on placebo (all patients were also on a statin). With respect to evolocumab, I found the following data:
1. A 52-week placebo-controlled trial of evolocumab in patients with hyperlipidemia published in the New England Journal of Medicine in 2014 found the mean change from baseline for fasting glucose at week 52 was 1.3 mg per deciliter for evolocumab and 0.4 mg per deciliter for placebo. The mean change from baseline for HbA1c at week 52 was 0.02% for evolocumab and 0.00% for placebo (table 3 and supplementary table S3).
1. The Osler trials recently published in the New England Journal of Medicine showed that 1.1% of the patients who received evolocumab developed diabetes, as compared to 0.7% of the patients in the standard of care group.
What do all these small differences add up to? It’s not possible to say yet, but I assume someone will do a meta-analysis at some point, and there may be some discussion of this issue in the FDA review of these agents, which will be posted prior to advisory committee meetings.
I should note that even if PCSK9 inhibitors do increase blood glucose and the risk of developing diabetes, they would still be very worthwhile for patients who are at significant risk of heart attack and stroke, if they are shown to be effective and have acceptable safety.
BMJ: Clinical trial data for all drugs in current use must be available for independent scrutiny
In an impassioned editorial, BMJ editor Fiona Godlee calls on the pharmaceutical industry to release clinical trial data on all approved drugs, and on medical journals to publish industry-funded trials only when there is a commitment to make patient-level data available on reasonable request. She states that the BMJ will require this commitment for all clinical trials of drugs and devices, whether industry-funded or not, beginning in January 2013. In addition, BMJ is publishing online all correspondence between Roche and the Cochrane Collaboration researchers regarding the oseltamivir (Tamiflu) data. More on the battle for Tamiflu data here.
Addendum 11/2/2012: read Pharmalot’s coverage here.
BMJ editor: Open letter to Roche about oseltamivir trial data
In BMJ:
Roche promised in 2009 to release full reports from clinical trials of oseltamivir in response to an investigation by the BMJ and the Cochrane Collaboration. In this open letter to John Bell, regius professor of medicine at Oxford University and a Roche board member, the BMJ’s editor in chief further urges the company to disclose the full data.
Read the full letter here.
Background here.
Johns Hopkins to launch Center for Drug Safety and Effectiveness
Johns Hopkins is launching a new Center for Drug Safety and Effectiveness. Via G. Caleb
Alexander,
On Wednesday, October 24, we will launch the Johns Hopkins Center for Drug Safety and Effectiveness, a collaborative effort of the Bloomberg School of Public Health and Johns Hopkins Medicine. The Center will fulfill its mission by supporting individuals engaged in research, training, clinical programs and public service to optimize the safe and effective use of prescription medicines in the United States and around the world.
We are delighted that Dr. Mark McClellan will deliver the inaugural lecture for the Center on October 24 at 4:00 PM, with a reception to follow.
Compare and contrast: two review articles on ezetimibe
For the past several years I have been following the ezetimibe controversy (see these posts on Gooznews and this blog here, here, here, here, here, here, here, here, here, here, here, here, here, here, and here). In my view, we continue to lack evidence of ezetimibe’s clinical benefit, or even safety, 10 years after FDA approval.
I have a Google Scholar Alert for ezetimibe, so often links to articles on ezetimibe arrive in my email inbox. Recently, two review articles on ezetimibe were published that were a study in contrasts. The first, by Sheila Doggrell, takes a skeptical view toward ezetimibe and reaches the following conclusion:
The comparison of clinical trials with simvastatin and ezetimibe alone and together has clearly shown that simvastatin decreases LDL-cholesterol and this is associated with improved clinical outcomes. Also, ezetimibe alone or in the presence of simvastatin lowers LDL-cholesterol. However, ezetimibe alone or in the presence of simvastatin has not been shown to have any irrefutable beneficial effects on clinical outcomes. Thus, until/unless the use of ezetimibe is clearly shown to improve clinical outcomes, its use should be largely restricted to clinical trials investigating clinical outcomes, and ezetimibe should not be used routinely in everyday practice.
The second, by Binh An Phan, Thomas Dayspring and Peter Toth, takes a much more optimistic view:
In the current treatment of cardiovascular disease, many subjects fail to reach LDL-C targets or remain at high risk for CHD events despite optimal statin and medical therapy. Ezetimibe inhibits intestinal cholesterol absorption and is effective in lowering cholesterol as monotherapy or in combination with statins in several populations, including those with FH, sitosterolemia, and insulin resistance. Significant controversy has been generated regarding the clinical effectiveness of ezetimibe, particularly after the publication of ENHANCE and ARBITER-6 despite both trials having significant methodological flaws that limited their ability to evaluate the benefit of ezetimibe. Growing data suggest that ezetimibe in combination with statin has a positive effect on the progression of atherosclerosis and reduces cardiovascular events in subjects at risk for CHD, including those with chronic kidney disease. Results from IMPROVE-IT are forthcoming and may help to guide better the use of ezetimibe in very high-risk CHD populations. Until that time and based upon the current available data, ezetimibe should remain a viable adjunct to statin therapy in the treatment of hypercholesterolemia.
Dr. Phan and colleagues find reasons to dismiss the negative results of ENHANCE and ARBITER 6-HALTS as due to “methodological flaws” and use copious amounts of hand-waving to find support for ezetimibe in the SEAS and SHARP trials, even though those trials compared the combination of simvastatin and ezetimibe with placebo and thus can tell us nothing about what, if anything, ezetimibe added to those results. Could the differing views of Doggrell and Phan et al. have anything to do with the fact that Dr. Doggrell declares no conflicts of interest relating to ezetimibe, while Phan, Dayspring and Toth declare the following conflicts:
Binh An Phan is a speaker for Abbott. Thomas Dayspring consults for Abbott, GSK, Health Diagnostic Labs, Kowa Company, Eli Lilly, Merck, Genentech, The Roche Group, Genzyme, and Omthera. He is on the Lecture Bureau for Abbott, GSK, Health Diagnostic Labs, Kowa, Eli Lilly, LipoScience, Merck. Peter P Toth is a speaker for Abbott, AstraZeneca, Amylin, Boehringer-Ingelheim, GSK, Kowa, Merck and consults for Abbott, Aegerion, AstraZeneca, Atherotech, Genzyme, Genentech, Kowa, and Merck.
It is not too surprising that authors who are consultants and on the speaker’s bureau for Merck would take a favorable view of ezetimibe. What is surprising is that anyone would take their word for it.
References
Doggrell SA. The ezetimibe controversy — can this be resolved by comparing the clinical trials with simvastatin and ezetimibe alone and together? Expert Opin. Pharmacother. (2012) 13(10):1469-1480.
Phan BAP, et al. Ezetimibe therapy: mechanism of action and clinical update. Vascular Health and Risk Management 2012:8:415-427.
Addendum, May 5, 2015: Unfortunately, the GoozNews blog is no longer up on the web.
Lauer: is Qnexa a lemon or a peach?
Qnexa, a combination of phentermine and topiramate, is a proposed anti-obesity medication. Although clinical trials demonstrate that Qnexa can lead to an approximately 10% weight loss, an FDA advisory committee recommended against approval in 2010 because of safety concerns (an increased risk of cleft lip and palette and increased heart rate, which could increase the cardiovascular risk). On February 22, 2012, an FDA advisory committee voted 20-2 in favor of approval, based on an additional submission by the sponsor, Vivus Inc.
In a commentary in Annals of Internal Medicine, Michael Lauer of the National Heart, Lung, and Blood Institute explains why he voted against recommending approval. Briefly, he discusses how the small pre-approval trials conducted by the sponsor, and the small number (12) of major cardiovascular events that occurred during those trials, give us insufficient information to determine whether Qnexa increases the risk of cardiovascular events. Qnexa is thus like a used car that could be either a “lemon” or a “peach.” In addition, based on prior experiences with obesity medications that were withdrawn from the market due to cardiovascular effects, we have reason to be concerned about an obesity medication that increases heart rate (consider the case of Meridia, previously discussed on this blog here and here). Finally, the sponsor’s argument that certain improved biomarkers, such as blood pressure and high-sensitivity C-reactive protein, outweigh any effect of the increased heart rate, fails to assuage his concerns given the failure of surrogates in the past. He states that “We cannot assume that just because a drug reduces weight and improves some biomarkers that it will be safe, let alone beneficial.” I completely agree. Here is his conclusion, but his commentary is open access, so I urge you to read it in full:
So what to do? We can resolve the information asymmetry by insisting on a large-scale, preapproval cardiovascular outcomes trial of Qnexa. It would be too risky to rely on postapproval surveillance or to hope that a rigorous trial could be conducted in a timely manner. If Qnexa prevents cardiovascular events, or at least doesn’t increase the risk for them, in a preapproval trial, then we will all know that we have the peach we’ve been waiting for.
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