Saturday, June 11, 2011

Actos Causes Bladder Cancer. Maybe We Should Have Kept Avandia?

Both Germany and France have now suspended the marketing of Actos (pioglitazone) due to concerns of a link between Actos and  bladder cancer.  Though we have known about bladder cancer concerns for some time, these recent concerns about the bladder cancer link stem from a recent report analyzing the FDA's Adverse Event Reporting System (AERS), which found that 93 cases of cancer were recorded between 2004 and 2009 in patients treated with antidiabetic drugs of which 31 patients were treated with pioglitazone, representing a statistically significant increased risk of bladder cancer (ROR 4.30, 95% CI 2.82-6.52; p<0.0001). Interestingly, the FDA announced that it was going to look into the link between Actos and bladder cancer only a few days before it made it's final decision on what to do with Avandia (as if they didn't know about the Actos cancer risk before the July 2010 advisory board). 

Despite the many things you have heard about Avandia, back in July 2010, the FDA decided to severely restrict the use of Avandia for three reasons:
1. Despite limited and conflicting data, there seemed to be a signal of myocardial infarction for patients taking Avandia.
2.  The one study proving Avandia's safety, RECORD (see here for more details) was discredited by FDA scientists due to potential reporting errors.
3. The advisers on the panel felt strongly that despite limited and conflicting evidence, the signal was enough to be concerned AND because Actos (similar drug in same class) did not seem to show this signal, why would doctors ever want to prescribe Avandia?

I have blogged extensively about Nissen's meta-analysis that triggered the whole Avandia scare. Meta-analysis have major limitations.  Another group of researchers using the same data as Nissen's with different statistical  techniques concluded that Avandia did not cause heart attacks.  Large, randomized trials are the only way to determine certainty, and all available large trials (DREAM, ADOPT, ACCORD, etc.) with rosiglitazone showed no heart attack risk.  As mentioned above, the one study designed to definitively show whether or not Avandia led to cardiovascular risk (RECORD, which showed that Avandia did not cause cardiovascular risk, and in fact surpasses the FDA's standard for cardiovascular safety) was harshly criticized by those within the FDA that wanted to see Avandia pulled from the market.  Specifically, the FDA found that GSK had some errors in reporting the results of RECORD.  Though these types of errors are not uncommon in very large trials, and likely won't affect the overall results of the study, nonetheless, the deserve looking into.  However, the FDA promised to do a complete independent analysis of the RECORD results; a promise it has yet to deliver on.

The main issue here is #3: Actos appears to be safe, so let's dump Avandia. (Interestingly, independent cardiologists analyzed all the data and did not find a conclusive difference in cardiovascular risk between Actos and Avandia).  Here is the full transcript of the advisory board.  Since it is a very difficult document to read through, I have pasted some of the direct quotes below from some of the advisers who voted to either remove Avandia from the market or severely restrict its use. Based on these quotes, I feel pretty strongly that had the advisers known about Actos' bladder cancer risk, that they may have voted very, very differently.  However, the FDA did know about the association between Actos and bladder cancer.  They just chose not to mention it!   In fact, when one adviser brought up the question at the July advisory board, the FDA only briefly mentioned this and discussed it more as a class effect also seen with dual PPAR agonists.

Avandia and Actos help diabetics use their own insulin better by hitting a receptor called PPAR. There are three main PPAR receptors: Alpha, Gamma and Delta.  We don't know a whole lot about delta, but PPAR Gamma works on glucose, and PPAR alpha affects cholesterol.  Fibrates like gemfibrozil, which lower triglycerides and raise HDL or good cholesterol are PPAR alpha agonists.  Dual PPAR agonists were drugs that pharma were trying to develop that hit both alpha and gamma in order to help both with lipids and glucose.  They have not been able to make it to market due to safety concerns (raised by, guess who??? Dr. Nissen). One of the differences between Actos and Avandia, is that Actos has a higher affinity for the PPAR alpha receptor, which is why it likely does a better job on raising HDL and lowering triglycerides than Avandia.  Some have hypothesized that this might be the reason why Actos might not have the same cardiovascular issues as Avandia (though this has yet to be shown).  If in fact, as stated during the FDA meeting (I am not aware that this data is published) that the bladder cancer risk was seen in both Actos and the dual PPAR agonists.  Bladder cancer has not been seen with Avandia.  In other words, the evidence (both available and suggested by FDA quotes that are public record) suggest that Actos may have more of a bladder cancer risk than Avandia. 

Why the FDA in discussing to keep Avandia on the market would not extensively discuss the concerns of bladder cancer with Actos, paired with the weak and controversial data showing Avandia's cardiovascular risk and effort to discredit GSK's study proving Avandia's safety leads me to believe that the FDA's attack on Avandia was very much politically motivated.  Scientists look at all the available data and weigh the risks and benefits of all options before making a conclusion.  It is clear to me that the FDA's decision on severely restricting Avandia was more political then science. Based on the currently available data which now include bladder cancer risk, Avandia may actually be a better choice than Actos, but the FDA's restriction will essentially prevent any doctor from being able to prescribe Avandia after November.

Select quotes from advisers who voted to voted to either remove Avandia from the market or severely restrict its use:
DR. SCHAMBELAN: This is Morrie Schambelan. I voted E. (remove Avandia from the market) . I was one of the brain-dead kangaroos last time (meeting in 2007) who was on the fence, largely because I did see a signal for harm. I was led at that time by the comparison to active comparators, which I think is much more relevant to me than placebo. I wasn't swayed by the pioglitazone data that were presented at that time because they were pretty preliminary. I was much more persuaded this time, including Dr. Graham's analysis. I feel that pioglitazone is a perfectly acceptable alternative.

DR. SAVAGE: Peter Savage. I voted D (keep on the market with restrictions) I was also oscillating between D and E because I think that the evidence of potential harm associated with rosiglitazone is stronger now than it was in 2007. And very importantly, the evidence about pioglitazone is substantially greater than what we saw treat in 2007.

DR. FLEMING: Fleming. I voted E. My main sense about this is really explained in my answer to question number 7. There's very concerning data about safety with rosiglitazone. It's not definitive, but if TIDE is to provide that, we have many years before we're going to get that insight. We do have an alternative, pioglitazone, for which there is considerably strong safety experience. So I come down to, then, what is the continued role for rosiglitazone?

DR. THOMAS: Abraham Thomas. I voted E. The scientist in me says we should always seek the truth. But this isn't an NIH study section. This isn't the review of a journal for publication. Really, what this is is an intersection, as someone mentioned at lunch, between public policy and science. And when we look at it that way, we can't always have the absolute truth to make a decision. We have other classes that are available that we never had before for the treatment of diabetes. And if rosiglitazone was removed from the market, we still have another TZD, what has had a trial that does demonstrate no increased cardiovascular mortality, no increased cardiovascular events, in PROactive.

Wednesday, June 8, 2011

Don't Take High Dose Simvastatin!

Today the FDA just announced a new warning on the highest dose of simvastatin, the most popular cholesterol medication prescription in the country.  They have issued this warning because "the highest approved dose--80 milligram (mg)--has been associated with an elevated risk of muscle injury or myopathy, particularly during the first 12 months of use."
The current recommendation is not to start simvastatin at 80mg and only to continue taking the 80mg if you "have been taking this dose for 12 months or more and have not experienced any muscle toxicity. It should not be prescribed to new patients.

First, why is this announcement so important.
As Forbes' Matthew Herper points out in A Snapshot Of The Cholesterol Drug Market, though Lipitor is the biggest selling drug in terms of dollars, generic simvastatin is actually the most commonly prescribed cholesterol lowering  medication.  As you can see from the graph below (viewed much better on the Forbes site), once Zocor became available as generic simvastatin, it became the most popular statin written (blue line) whereas Lipitor (red line) prescriptions continue to tumble. Over time, insurance companies have made it more and more difficult to write for any branded statin by increasing co-pays for patients or increasing hurdles to get prescriptions approved.

In fact, simvastatin makes sense for many patients.  Most data suggest that benefit is derived from statins when they reach about a 30% reduction in bad cholesterol, or LDL.  The folks at the NIH's NHLBI have evaluated the efficacy of all the available statins (see below) and you can see that most statins will achieve that goal at various doses.  For example 10mg of atorvastatin (Lipitor), 20-40mg of simvastatin, and 5mg of rosuvastatin (Crestor) all lower LDL cholesterol by about the same amount.  Thus, if you just need a 30% reduction in LDL, you should be fine with the generic.  Problem is that many patients need more than that amount of reduction.  Thus, if you want to stick to a generic, you would have to go to 80mg of simvastatin.

Now one might thing that the stronger, more potent the statin, the more likely it is to cause side effects.  Turns out the opposite is true.  The graph below shows that when plotting LDL reduction against number of patients developing myopathy (what the FDA is concerned about), it seems like the more potent statins (Crestor, Lipitor) not only lower cholesterol better, but have a lower risk of myopathy. Myopathy is pretty uncommon, usually only about 1/10,000 or 0.01%. Looking at both Lipitor and Crestor, you can see as the dose goes up (10, 20, 40, 80) the percent of reduction of LDL continues to improve, but rate of myopathy is pretty much the same except for a slight bump at the 80mg dose of Lipitor.  (Though not on the graph, you can see why the 80 mg dose of Crestor wasn't approved, because at that dose there was significant myopathy). However, when you jump from 40-80 mg of simvastatin, the LDL only goes up a few points, but the rate of myopathy skyrockets to over 1% (that's 1/100 instead of 1/10,000).  Finally, you can why cerivastatin or Baycol was pulled from the market.  It was pretty weak at lowering LDL, but had up to 2% incidence of myopathy at the higher doses.

The good news is that Lipitor will go generic in only a few months.  When that happens, I am sure that the graph above will change drastically.  All Lipitor scripts will likely go to the generic medication and probably many of the simvastatin prescriptions will also switch to generic atorvastin, since it is a better statin (more potent, fewer side effects).  Crestor is another option (most effective, fewest side effects), but will not go generic for a while. The other thing to note is that Pfizer, who is about to lose Lipitor, is trying to get as much business as it can by offering patient coupons, so that (as long as you are not on Medicare part D or Medicaid) a prescription of Lipitor will only cost you $4 until it goes generic. 

Bottom Line: All statins are not created equal and generic is not always best.  If you are on Simvastatin 80mg, you should seriously discuss with your doctor about switching.  In fact, if you are on simvastatin at any dose and not on Medicare part D or Medicaid, but have commercial insurance, you should consider asking your doctor about switching to Lipitor with the $4 coupon (you may actually save money by NOT taking the generic) until it too goes generic.

Saturday, June 4, 2011

What to do about Niacin?

I have been getting a lot of questions regarding the use of Niacin since the media recently reported that the NIH had stopped their AIM-HIGH study. AIM-HIGH was designed to see if adding Niacin to patients on a statin who still had low HDL and high triglycerides would improve cardiovascular outcomes (heart attacks, strokes). Though we know that high triglycerides and low HDL are both strongly associated with heart disease, that Niacin will raise HDL and lower triglycerides and even few early studies did show raising the HDL with Niacin did work; this large, randomized NIH sponsored showed no evidence of improvement.  Though the actual data from the study has not been released, we do know that the NIH stopped the study a year early because there was no benefit seen and possibly some harm in the form of excess stroke.  One possibility is that patients were taking statins at doses that lowered their LDL to very aggressive levels (target range of 40-80). Some have postulated that with an LDL that low, you will never get a heart attack or stroke.  So, Niacin may indeed work, but not with super reductions of LDL's with statins.

One of the main points of from these findings is that we have to be careful when it comes to using surrogate endpoints (like LDL and HDL) for treatment.  For example, lowering the LDL with a statin reduces heart attacks and strokes. However, lowering the LDL with ezetimibe (Zetia) doesn't seem to do this (see here for more details)  This might be the case for Niacin and HDL as well. 

I have never been a big fan of Niacin because it causes pretty bad flushing, increases uric acid/gout, and most importantly raises blood glucose.  Most of my patients are diabetic/prediabetic, so raising their blood sugar is not something I am too fond of.  The other drugs that can raise HDL and lower triglycerides are fibrates. Gemfibrozil has clearly demonstrated this in a large VA study (VA-HIT).  The problem with gemfibrozil is that it can interact with statins, causing some serious side effects.  Statins are the one med that clearly works in just about everyone with increased cardiac risk.  Fenofibrate works the same way, but can be used safely with a statin.  However, when they tried to demonstrate cardiovascular improvements with fenofibrate (FIELD study), the primary outcome was not statistically significant.  One of the differences between VA-HIT and FIELD is that more patients were on statins in FIELD, since FIELD was a more recent study and regular use of statins had become standard of care.  However, in the diabetic patients with low HDL and high triglycerides, the FIELD study did show that fenofibrate reduced heart attacks and strokes. The ACCORD lipid study (another large, randomized, NIH sponsored trial), attempted to prove benefit by adding fenofibrate to all diabetics on a statin, but failed.  However, similar to FIELD, in those diabetics with low HDL and high triglycerides, fenofibrate added to a statin did reduce heart attacks and strokes. The consistency of these findings therefore have some merit. 

Bottom Line: Statins remain the first choice for patients at increased cardiovascular risk and should be used at doses that meet individual LDL goals and/or lower LDL by 30-40%.  After that, the rationale for treating low HDL/high trigs is now less clear. Before we see the actual data from the AIM-HIGH study, it would be premature to pull all patients off of Niacin.  That being said, in my opinion, Niacin's days are likely numbered.  Evidence for raising HDL and lowering triglycerides seems to be much stronger for fenofibrate, at least in diabetics, and fenofibrate does not seem to have the negative effects, specifically hyperglycemia, seen with Niacin.