Archive for March, 2008

ENHANCE results published; experts weigh in

 Vytorin

This is a f/u to the piece I wrote in January describing the preliminary (but widely publicized) results from the ENHANCE study of simvastatin and ezetimibe (Zetia) (combination tablet sold as Vytorin by Schering-Plough and Merck) in patients with familial hypercholesterolemia.  The study looked at the effects of the combination versus simvastatin alone on carotid intima-media thickness.  My previous opinions of the study’s meaning aren’t changed with publication of the final results in the NEJM to coincide with the ACC meeting.  In case you were asleep for the past couple of months, ENHANCE was negative for signs of IMT improvement with the combo. 

Expert opinion of the findings has been decidedly negative and prescriptions for ezetimibe (a $5 billion a year drug, counting both Zetia and Vytorin) have tumbled.  Schering-Plough reported that scripts were 3.2 million in January and 2.8 million in February for both drugs combined (a 12.5% drop), while others have reported that Vytorin scripts have fallen 18%.  Several sell-side analysts believe the latest pronouncements from experts at the ACC will further erode sales of Zetia and Vytorin and have cut their sales forecasts and share-price targets for Merck and Schering-Plough.  Given the overreaction to the results thus far, it’s hard to find fault with their reasoning.

I await results from ongoing studies (particularly IMPROVE-IT) with hard CV outcomes as the primary endpoint in a less highly selected population before changing my own use of Zetia.   If ezetimibe doesn’t work to reduce hard CV outcomes despite robust LDL-C reductions, the findings will be strong evidence supporting pleiotropic benefits of statins and arguing against routine use of ezetimibe.  If ezetimibe does work, the utility of CIMT progression in hypercholesterolemia will be dubious. 

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Consumers Union’s misguided approach to improving drug safety surveillance

Consumers Union Petition

Petition for Better Reporting of Drug Side Effects
I support requiring all drug ads to include a 1-800 number and website so citizens can report drug side effects (petition docket 2008P-0012/CP1).

All too often, drug advertisements fail to present the benefits and risks of using prescription drugs in an accurate and balanced way. It is often the newest drugs that are the most heavily advertised, and it is these drugs whose side effects we know the least about.

The current system for collecting information about side effects catches only a fraction of actual cases. The recent law passed to require print drug ads to provide a 1-800 number and website (FDAAA — P.L. 110-85) is a step in the right direction, but should be extended to include TV ads which are viewed far more frequently and with a greater command of the viewing audience.

Increased reporting of adverse events will help in the earlier detection and better analysis of problems. All television ads should contain information on how patients can report side effects to the FDA.

As you can read above, Consumers Union is trying to improve surveillance of drug safety by promoting patient reporting of “side effects” in drug ads.  A representative of the organization had asked me to blog about the petition, so I am. 

I oppose their effort. Here’s why.

Probably around 1% of adverse reactions to drugs are reported via FDA’s Medwatch system.  Most reports come from healthcare professionals, based on my experience reviewing such reports in the 90’s.  That’s the way it should be, and we need to encourage more of it. 

On the other hand, encouraging more reporting af “side effects” by consumers might actually have its intended effect, which could completely break an already shaky surveillance system. 

Pasive surveillance of reported events can be an effective way of uncovering signals that a drug is associated with rare but potentially serious adverse effects (like hepatic toxicity) or with adverse effects that occur on a background of a common disease (like heart disease) at moderate relative risk (like the risk of heart attack with Vioxx, for instance). 

There are real challenges when interpreting data from such types of surveillance programs.  The most obvious challenge is that there is no concurrent control group for comparison to the drug-treated group (when there is a concurrent control group, we’re speaking of a form of surveillance that is different from the type I’m describing).  A less obvious challenge is separating signal from noise in the data.  Signals are so-called true-positive adverse event reports.  Noise comes from false-positive reports.  Safety surveillance systems strive to maximize signal and minimize noise in order to provide the best possible opportunity for making correct inferences from the data. 

When there is a low percentage of adverse events being reported overall, as in the current environment, the signal is low, and so the detrimental effects of any noise are amplified.  The situation will be improved by encouraging more adverse reports with a high chance of being true-positives and by discouraging reports with a high chance of being false-positives.  How do we do this?

We don’t do it by encouraging patients to fill out Medwatch forms or by calling 800 numbers.  We do it by making it much easier for doctors to capture and transmit adverse events that are possibly or probably related to drugs and by making it much easier for FDA to capture and analyze such reports.  The technology for facilitating such data capture and interchange already exists.  The technology on the doctor end is the electronic medical (health) record (EHR).  Interchange allowing upload of data to FDA can be facilitated using the HL7 data standard known as ICSR.  And on the back end, FDA already uses analytical tools that can make sense of the incoming data.  It is simply a matter of mandating use and providing funds for its implementation. 

Doctors can’t afford EHR for the most part, which is the main reason why its adoption has been so painfully slow.  In an EHR environment, a passive surveillance system can flourish by giving doctors easy, pain-free ways to report anonymized AE reports directly to FDA or other surveillance agencies (like CDC).  It can be as easy as adding a couple of tick boxes and a “send” button to a standard electronic patient encounter form (okay there’s more to it than that, but no so far as end-users can tell).

The US government has not done enough to encourage adoption of this technology, which would really improve drug safety surveillance.  The government should be buying EHR systems and associated training and support for every physician office until the technology achieves saturation.  By becoming the buyer, HHS can mandate that systems be sematically interoperable (be able to talk to each other and to FDA unambiguously).

The cost wouldn’t be as high as you might think.  According to the 2007 US economic census (2002 data), there are roughly 205,000 physician offices in the US.  Some of these offices (let’s say for argument-sake it’s 10%) already have EHR systems, but let’s figure that the government provides support for every office.  Because of discounts from competitive bids, the average cost per office will be much lower than it is today.  Let’s say it’s $50,000 per office on average.  That’s roughly 10.25 billion dollars to outfit, train, and support every physician office in the US with an EHR system and to guarantee that the systems will be interoperable with each other and with FDA.  That’s about what the US is spending each month in Iraq.

That’s what Consumers Union should be pushing for.  Adding to the noise of passive surveillance data will only make a bad situation worse.

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Grassley seeks GAO input into use of surrogates and postmarketing followup by FDA

S. Sen. Grassley: Secures independent review of FDA approvals based on narrow health benefits - FierceBiotech

In his letter to the GAO, Sen. Grassley asks for an investigation into FDA’s use of surrogates for product approval and whether FDA has appropriately followed up drugs approved initially based on surrogate markers.  He cites recent examples of Avandia and Vytorin as cases where the system hasn’t worked as intended.

Is he right?

Avandia was aproved on the basis of a surrogate marker, HbA1c, but the marker is a surrogate for the effects of chronic hyperglycemia on the body.  It is not a proven surrogate for the outcome of heart disease, as Sen. Grassley implies. 

The effects of chronic hyperglycemia in patients with Type 2 diabetes that are well established include heightened risks of diabetic microvascular disease, which is associated with diabetic nephropathy, retinopathy, and neuropathy and their sequelae.  There is decent evidence that reduction in chronic hyperglycemia reduces the risk of these serious health outcomes.

There is also reasonable evidence for associations of chronic hyperglycemia with other diabetes sequelae that relate to microangiopathies.  The evidence for an independent effect of chronic hyperglycemia in Type 2 diabetes on macrovascular diseases, which include heart disease, is much weaker.  Therefore, to say that FDA failed in its duties by approving a drug based on its effects on hyperglycemia alone is disingenuous. 

On the other hand, I’ve long supported large premarketing simple safety studies for drugs to be used chronically in large populations (see here, for example), so if Sen. Grassley’s intention is to try to make such studies a requirement, I support him.  I just don’t support his implication that FDA shouldn’t have relied on reduction in HbA1c as a demonstration of efficacy.  It was then and is now an adequate surrogate endpoint for many of the detrimental effects of chronic hyperglycemia due to Type 2 diabetes.

The other chosen example, Vytorin, is another poor one to use against the choice of a surrogate to claim eficacy.  As I’ve explained in an earlier post, the ENHANCE study did not establish the lack of efficacy of Vytorin or Zetia, as Sen. Grassley implies.  It merely demonstrated that in a highly selected population of patients with atypical hypercholesterolemia, the use of Zetia with statin failed to reduce progression of carotid intimal thickness, itself an unproven surrogate measure for the outcome of cardiovascular death or disability.  Genuine cardiovascular outcomes studies with this class of drug are underway.

Was Sen. Grassley wrong to imply that makers of drugs used to lower LDL-C or raise HDL-C should be required to do hard outcomes studies prior to approval?  Yes and no.  For the statin class, there’s little doubt that using LDL-C as a surrogate is justified, given the benefits on heart disease risk reduction shown with several class members, at least in patients with established heart disease at baseline.

For other classes of drugs, including the class containing Zetia/Vytorin, I think he’s mostly right, with one exception.  There are some diseases independently associated with high cholesterol in the blood that are amenable to treatment with drugs that lower blood cholesterol.  However, these conditions are rare and typically affect only those patients with very high lipid levels.  So, generaly speaking, I agree with the implication and with the sentiment.  Drugs used to lower LDL-C that will be used primarily by people like me who hope to reduce their risk of heart disease should be studied rigorously in the premarket setting, and such study should include evaluation of their effects on disease outcomes, rather than unproven surrogates (both LDL-C and CIMT, in the case of Zetia/Vytorin).

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