Plavix and 2C19 BrewHahHah

Yes,

I am a little slow

Yes,

It has been a long time.

But,

I am back. With a serious hankering to smash some studies. I already pooh pooh'd the Migraine SNP study on Twitter, but the Plavix stuff.....That deserves a blogpost.

To quote a famous caridologist and friend

"If Plavix really didn't work for 30% of patients, why don't we see more in-stent thrombosis?"

Translation: Your science is nice, but how does it fly in the real world?

I have to tell you, at first I couldn't answer. It was a great question. Do a full third of people have that severe failure?

The obvious answer is NO. If 1/3 rethrombosed, we wouldn't be using Drug Eluting Stents.

So what is the answer:

Apparently a BMS (I.E. Plavix maker) funded study investigated this

We hypothesized that the benefits of clopidogrel as compared with placebo would be decreased in persons who carry a loss-of-function CYP2C19 allele and increased in carriers of the gain-of-function *17 allele.

What did this team study?

we examined the efficacy and safety of clopidogrel as compared with placebo according to genotype status among patients in two randomized trials: the Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) trial, in which patients with acute coronary syndromes were enrolled, and the Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events (ACTIVE) A, in which patients with atrial fibrillation were enrolled.

Ok, so they took 2 different populations and bundled them into the same article....

The 2 studies?

CURE-randomized, double-blind, placebo-controlled trial comparing clopidogrel (at a dose of 75 mg per day) with placebo — both in combination with aspirin — among 12,562 patients with acute coronary syndromes without ST-segment elevation.

ACTIVE A- was a randomized, double-blind trial comparing clopidogrel, at a dose of 75 mg per day, with placebo — both in combination with aspirin — for reducing the risk of stroke among patients with atrial fibrillation and at least one additional risk factor for stroke who were not eligible for warfarin therapy.

What did they find? No difference between Poor Metabolizer and Wild Type in secondary and primary outcomes.

So are we wrong with our studies showing 2C19 genotype matters in outcomes?

Probably not.

1st the authors note why.

1. One possible explanation for the divergence between our findings and those of previous studies involving patients with acute coronary syndromes is the difference in the rates of PCI with stenting. Only 18.0% of patients in the CURE population included in our study underwent PCI, and only 14.5% underwent PCI with placement of a stent, as compared with more than 70% in previous studies

2. We cannot definitely exclude the possibility of an interaction in the subgroup of patients who receive stents, particularly those who receive drug-eluting stents, which were not in use at the time of the CURE trial.

3. the ACTIVE A genetic data set contained fewer participants and outcome events than did the CURE data set and therefore had less statistical power.

My take

The ACTIVE A trial to assess the hypothesis was powered at 45% to detect a difference, thus it is a worthless study and should not be included in this analysis.

While I agree that a placebo group may be useful. It is not needed to assess a difference between people using Plavix with normal Plavix metabolism and Poor metabolism. In fact it may even confuse the situation as it introduces further confounding factors not genotyped or phenotyped out.

The authors disagree
First, the inclusion of a randomized placebo group in our analyses reduces various sources of confounding, such as potential pleiotropic genetic effects or population stratification.

Well, did they test or assess for pleiotropic genetic effects? No.

Further, by introducing a study COMPLETELY underpowered to observe and eval the hypothesis into this article, it ONLY creates a false image of scientific validity.

The authors disagree
Third, we observed consistent benefits of clopidogrel, irrespective of CYP2C19 genotype, in two different patient populations, which validates our findings and suggests that they could be generalizable to other populations.

Again to quote the article

Among patients with atrial fibrillation in ACTIVE A, our study had much lower power (45%) to detect a similar interaction.

So why did they include the POORLY POWERED study?

" in two different patient populations, which validates our findings and suggests that they could be generalizable to other populations."

While I laud the effort to have Randomized and Observational versus retrospective efforts. I think we have to be very careful in our study design to make sure

1. We are properly powered to observe differences.
2. That we assess pleoitropic effects, rather than claim to control for them mysteriously.

The Sherpa Says: Why include the second study? It is improperly powered, further the CURE study did not include Drug Eluting Stents! Why? Plavix goes generic in 2011. They did this to save the market......Expect more screwy studies published in NEJM etc. As PGx gains traction, contrarians and Pharm will always fight it.....

Pharmacogenetic Indication for a Medication?

That's one way to market the newest medication to prevent stroke, heart attack or stent thrombosis.

Wha? Yes, I mean, Prasugrel otherwise known as Effient is FDA approved for use in these patients.

But one thing I was thinking is that, since the FDA put on the insert of Plavix that 2C19 testing may be useful to identify people who will not respond to Plavix (generic Clopidogrel)

Perhaps, the marketing geniuses over at Eli Lilly could use this as an FDA suggestion that these 2C19 people may be better off with Prasugrel.

Yes, it would be one of the most brilliant ways to market pharmacogenomics. I can only imagine the DTC genomics companies salivating over this "We offer the 2C19, test. Act now, save your life." Technically, It actually could. Yes, all the stops would be pulled out and it could potentially save the DTC genomics companies.

You may be asking yourself, "The DTC companies need saving?"

Yes, they do. Face facts, Research revolution is a flop, nowhere near 1000 people per study. Funny how people don't trust google or anyone without proper research accreditation.

Navi is slashing costs and they have a CEO who is the master of running wastelands (i.e. companies where all the bad assets of a VC firm go)
DeCodeMe.....huh?
Pathway and Tru have no marketing budgets and no real scientific staff.......... Seriously here. WTF?

But, if they could get one big hit from Lilly shoving billions into this PGx marketing campaign, they could be ok. Otherwise, I am afraid, they are lost.

For Lilly it would be a huge win too. Why? Imagine being able to pull a full 1/3rd of all patients taking Plavix off and switching them to Effient/Prasugrel. They could, they really, really could.

So now that I have you attention. The big question is , when will Eli Lilly do this? My guess, in the fall.

Mark my words, they WILL DO THIS and it WILL SAVE companies like 23andSergey and Navi. If of course they offer the test. LabCorp, Genelex and Quest all offer the test now.

But here's the rub, if they offer this and say it is used to make a clinical decision, then they will be a part of the healthcare industry......... Oops, forgot to mention that before. Survive and take regulations or Die..........

The Sherpa Says: This would be the most brilliant marketing campaign in the world, Personalized Medicine awareness would be worldwide, and Pharmacogenomics would hit the stage in a major, major way....Thanks Lilly, call me to orchestrate your campaign.....

Plavix, Plavix, Plavix

I just finished up giving a Yale Affiliated Hospitals Lecture to a bunch of residents on the topic of pharmacogenomics. Not to toot my own horn, but several residents came up to me and asked......"Why didn't I learn this in medical school?" Even better was the 3rd year medical students who just finished up Pharmacology last year....they said "The EXACT SAME THING".......

Ok, so here's my beef. Why in the hell aren't we teaching this in medical school. I know I have said this before......but what in the hell is going on here? We have data and not just data , but DAMN GOOD data....and instead we are still pumping JakStat pathways down the throats of our second year medical students.....

I have a very big problem here and I need it fixed. Why can't we get physicians who study PgX to teach this? It is simple really, I know many more doctors who like PgX than who like other sides of genetics.....why not let them in to teach these students????

I see no barriers other than cost of paying clinical faculty, which is always the barrier.....

That being said, even with the great Plavix data out there, we still have non believers....

An editorial in the Annals of Internal Medicine hints at it.

Entitled "Personalized genetic Prediction: Too Limited, Too Expensive, or Too Soon?"

It gives me a reason to say bull$h!t

The title is an eye catcher which most busy clinicians won't read, but instead use the title as a guide post for attitudes on this subject....Trust me, I know clinicians who did precisely that.

You see, the problem with this editorial is that it should have been titled "9p21 to predict cardiovascular risk: Too Limited, Too expensive, or Too soon?"

I love how the Annals completely makes a hash of what Personalized Medicine is!

A quote from the editorial

"As these studies show, we are still far from personalized medicine."

I guess Dr. John doesn't see pharmacogenomics as part of Personalized Medicine

Or maybe he just doesn't read the New England Journal of Medicine......

Either way.....this is not a responsible way to publish a journal and disseminate personal opinion.

I personally think it is because the ACP (American College of Physicians) does not have good advice on how best to get its body up to speed on this stuff.

But I know this is not exactly true, because they sponsor Mike Murray's Harvard course on the Genetic Basis of Adult Disease, which has one lecturer on Pharmacogenomics

So why? Why did they fail to include personalized medicine into the ACP meeting?

Why did they let this guy give the opinion that disease prediction was the only thing in personalized medicine?

Why? I have no clue. But I would love to have someone from the ACP tell me.......

Please!

The Sherpa Says: Education, Regulation and Litigation will be the drivers of this field.....Not the Data......That is a damn shame. And yes, I did go to Penn State!