Monday, September 8, 2008

Could Your Heart Medicine Cause Cancer?

There was a series of interesting articles in the last issue of the New England Journal of Medicine concerning a heart medicine called Vytorin. Perhaps you’ve seen the ads on TV. You know the ones… they show high cholesterol foods and a silly looking person dressed to look like the food to reinforce the idea that Vytorin has 2 medicines to address 2 ways your cholesterol could become elevated. In fact, Vytorin is a combination of Simvastatin, a drug that works by blocking your body’s ability to make cholesterol, and Ezetimibe, a drug that works by blocking your body’s ability to absorb cholesterol from the foods you eat.

In theory, this is a great idea. After all, cholesterol comes from 2 sources, why not create a drug that affects them both? This is exactly what Merck and Schering-Plough did in a joint venture using drugs that each company still had under patent.

Having created this drug, the pharmaceutical companies had to get the approval of the FDA to market it. Otherwise, they could not have aired those memorable ads. To earn FDA approval, a drug company has to provide data from a clinical trial showing the drug’s effectiveness. Vytorin was approved based on its ability to lower blood levels of LDL, the "bad cholesterol" that is associated with heart attacks and strokes. After FDA approval, the company launched another study called the ENHANCE study. This study was designed to show an effect on atherosclerosis ("hardening of the arteries"). It lasted just 2 years and enrolled 720 patients with a genetic disorder (familial hypercholesterolemia) that causes high cholesterol levels and heart attacks and strokes at a very young age. The study showed that Vytorin lowers cholesterol levels in these patients, but it did not detect a decrease in heart attacks or strokes.

Importantly, the study did not show that Vytorin was any better than Simvastatin alone.

There have been 2 drug company-sponsored trials since then: the SEAS trial (SEAS stands for Simvastatin and Ezetimibe in Aortic Stenosis) and the Improved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT) trial. Both studies were designed to test whether Vytorin reduces the risk of heart attacks and strokes better than Simvastatin alone. The results of the SEAS trial were released this week (The IMPROVE-IT trial is still ongoing). In a disappointment for the drug companies, Vytorin did not decrease the risk of progression of aortic stenosis (a narrowing of the valve leading from the heart into the aorta, the major artery that drains the heart) or on cardiovascular events in general.

Surprisingly, the patients taking Vytorin had an increased risk of cancer compared with patients taking a placebo.

What’s going on here? Does this new heart medicine not only not work, but also cause cancer?

The answer is probably not that simple.

When the data from all 3 trials are combined, there is no increase in the incidence of cancer in patients who take Vytorin. However, there was an increased risk of dying from cancer.

How could this happen?

Well, one possibility is that this is just a coincidence. The studies were not designed to detect a risk of getting or dying from cancer. So maybe it was a statistical fluke.

But it could be real. An editorial in the New England Journal accompanying the articles warns about this possibility. Ezetimibe inhibits the absorption of plant sterols from the diet, not just cholesterol. Epidemiologic studies have linked diets high in plant sterols to a lower incidence of cancer. Laboratory animals (mice and rats) fed a diet high in plant sterols show modest resistance to chemical carcinogens and to tumors grown from injected human cancer cells. Plant sterols have a number of inhibitory effects on human cancer cells grown in the lab. These findings could provide the basis for a plausible biological explanation for the results in the SEAS study.

I wrote this piece for two main reasons: one reason is that I think this case (and the fiasco surrounding Vioxx) is an important reminder not to be so eager to take a new drug just because it’s new and has a cute ad. FDA approval is no guarantee that a drug is safe, and some relatively rare but certainly very significant side effects only become noticed during what is called post-marketing surveillance. The other reason is as a teaser for my upcoming, first ever book review: Reasonable Rx: Solving the Drug Price Crisis, by Finkelstein and Temin.

Stay tuned.

Related Posts:
Is Vitamin D the Wonder Drug of the 21st Century?
Access to Experimental Drugs for Dying Patients
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Breaking News: the FDA (re)issues a warning about fentanyl
I can buy it over the counter, doesn’t that mean it’s safe?

This topic was also covered extensively by one of my friends in another blog. Read her posts here and here.


A Cancer Doc said...

I find this discussion interesting. A few years ago at ASCO, there was a flurry over HMG CoA reductase inhibitors with the suggestion that they might reduce the risk of cancer. As I recall, colon cancer got most of the press, but I found a talk also documenting an effect in breast cancer in a brief search of the abstracts. These were deemed early and preliminary studies with FU recommended, and no indication for this to become the "standard of care." The studies were accompanied with additional data regarding in vitro effects on cancer cell lines.

Since Vytorin inhibits absorption, slapping it on in vitro cell lines doesn't answer the question. Perhaps, the question could be asked in a xenograft model?

I am surprised that in the recent media flurry over Vytorin, there has been no reference to those previous studies looking at HMG CoA reductase inhibitors and their potential protective effects. Would presenting that data become too confusing or did I miss the studies debunking the early observations from a few years ago?

Marilyn Mann said...

I highly recommend this invited commentary by Thomas Fleming of the University of Washington on the statistical issues raised by the cancer data in SEAS, IMPROVE-IT and SHARP.

Ezetimibe was approved by the FDA based on its ability to lower LDL. Zetia was approved in 2002, Vytorin in 2004. The theory is that a drug that lowers LDL should also reduce the risks of heart attacks and strokes.

ENHANCE was a post-approval trial designed to show ezetimibe's effect on atherosclerosis. It compared simvastatin 80 mg/ezetimibe 10 mg with 80 mg simvastatin alone over a period of two years. The trial was not designed to show whether ezetimibe prevents heart attacks and strokes. In addition to the fact that the trial was only two years long, it was not "powered" to show ezetimibe's effect on cardiovascular events. In other words, you need a much larger number of people to show that. That is the purpose of IMPROVE-IT. Unfortunately, the results from IMPROVE-IT will not be available until 2012.

Whether drugs should be approved based on surrogate endpoints such as LDL levels or blood glucose is controversial. The argument for doing so is pretty weak, IMO, when there are already effective medications on the market for the disease in question. The FDA's decision to approve ezetimibe based solely on LDL-lowering is especially puzzling in view of the fact that (1) ezetimibe is a first-in-class drug (i.e., the first cholesterol absorption inhibitor to be approved), and (2) there are many other drugs already on the market that lower LDL. It would have been preferable for the FDA to require MSP to conduct a clinical trial testing ezetimibe's effect on heart attacks and strokes before approval.

In SEAS Vytorin had no effect on the primary endpoint or the secondary endpoint of aortic valve events. There was a 22% reduction in a secondary endpoint of ischemic events (i.e., heart attacks, strokes, death due to cardiovascular causes, bypass surgeries, etc.) in the Vytorin group as compared to the placebo group. Most of this 22% risk reduction was due to fewer bypass surgeries in the Vytorin group.


Doctor David said...

Thanks for your feedback, Marilyn. The commentary you point to is excellent. So is the JAMA article Surrogate End Points and FDA Approval: A Tale of 2 Lipid-Altering Drugs that you sent me earlier.

Cancer Doc, I haven't seen much recently in the clinical literature about statins and cancer risk. Not sure if that's because trials are ongoing, trials were negative, or something else. I do see papers from time to time in the basic literature about this, but as you know, what works in the lab may or may not work in an actual patient.

Marilyn Mann said...

If you do a search on you will find about 5-6 ongoing trials testing the effective of various statins on biomarkers or abnormal cytology in women who have been diagnosed with breast cancer or DCIS or who are at high risk for BC. This research is still very preliminary. It does not test the effect of statins on diagnosis of breast cancer or recurrence or anything like that.

The RCTs of statins have generally not shown fewer cases of cancer in people who received a statin. There are some observational studies that show such results, but one can imagine that people who take a statin are different from people who don't, so those studies aren't very convincing.

There is a meta-analysis in the Journal of the American College of Cardiology by Karas et al. looking at statins, LDL levels and cancer risk. It is available online -- may still be in press.

Anonymous said...

my family member in India is suffering form, we don't know what, neither do the doctors. The desease 10.2x8.7x8.6 cm on the left ventricle and is spreading throughout the heart. There is a mass effect seen over the left atrium, which has been compressed. If you know a doctor, or even you yourself, knows what this desease is and how it can be cured please email me at

Anonymous said...

The hospital that he is at is Dayanand Medical College and Hospital Ludhiana Depth of Radiodiagnosis and Imaging

The phone number is 91-161-4687063 or 4337627

The patient's name is Kirandeep Singh, Age 36/M, is in the care of Doctor Desusa

Anonymous said...

Thanks for this note.
There was a great banners and media announcement on that drug before.
First time for me know it is harmful. I will read indepth that relation and announce on my cardiology blog:

Doctor David said...

Wow. Thanks for the ongoing discussion on this important topic. I do want to clarify one thing in response to the comments by Proxy and Tabib. My point here was not to say that these drugs are harmful, but rather to emphasize the importance of post-marketing surveillance to look for these rare but potentially very important side effects. Our (American) society is quick to latch on to the "new and improved", sometimes even when the current standard is just fine. Sometimes "new and improved" is not as good as it seems.

steaven said...
This comment has been removed by the author.
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