This transcript has been edited for clarity.
Dr. O’Donoghue: We’re going to discuss a very important and emerging topic, which is the use of low-dose colchicine. I think there’s much interest in the use of this drug, which now has a Food and Drug Administration indication, which we’ll talk about further, and it’s also been written into both European and American guidelines that have been recently released.
who’s been at the forefront of research into anti-inflammatory therapeutics.
Lifestyle lipid-lowering paramount
Dr. O’Donoghue: As we think about the concept behind the use of colchicine, we’ve obviously done a large amount of research into lipid-lowering drugs, but where does colchicine now fit in?
Dr. Ridker: Let’s make sure we get the basics down. Anti-inflammatory therapy is going to be added on top of quality other care. This is not a replacement for lipids; it’s not a change in diet, exercise, and smoking cessation. The new data are really telling us that a patient who’s aggressively treated to guideline-recommended levels can still do much better in terms of preventing heart attack, stroke, cardiovascular death, and revascularization by adding low-dose colchicine as the first proven anti-inflammatory therapy for atherosclerotic disease.
I have to say, Michelle, for me, it’s been a wonderful end of a journey in many ways. This story starts almost 30 years ago for quite a few of us, thinking about inflammation and atherosclerosis. The whole C-reactive protein (CRP) story is still an ongoing one. We recently showed, for example, that residual inflammatory risk in some 30,000 patients, all taking a statin, was a far better predictor of the likelihood of more cardiovascular events, in particular cardiovascular death, than was residual cholesterol risk.
Think about that. We’re all aggressively giving second lipid-lowering drugs in our very sick patients, but that means inflammation is really the untapped piece of this.
The two clinical trials we have in front of us, the COLCOT trial and the LoDoCo2 trial – both New England Journal of Medicine papers, both with roughly 5,000 patients – provide very clear evidence that following a relatively recent myocardial infarction (that’s COLCOT) in chronic stable atherosclerosis (that’s LoDoCo2), we’re getting 25%-30% relative risk reductions in major adverse cardiovascular events (MACEs) on top of aggressive statin therapy. That’s a big deal. It’s safe, it works, and it’s fully consistent with all the information we have about inflammation being part and parcel of atherosclerosis. It’s a pretty exciting time.
Dr. O’Donoghue: It beautifully proves the inflammatory hypothesis in many ways. You led CANTOS, and that was a much more specific target. Here, in terms of the effects of colchicine, what do we know about how it may work on the inflammatory cascade?
Dr. Ridker: Our CANTOS trial was proof of principle that you could directly target, with a very specific monoclonal antibody, a specific piece of this innate immune cascade and lower cardiovascular event rates.
Colchicine is a more broad-spectrum drug. It does have a number of antineutrophil effects – that’s important, by the way. Neutrophils are really becoming very important in atherosclerotic disease progression. It’s an indirect inhibitor of the so-called NLRP3 inflammasome, which is where both interleukin-1 (that’s the target for canakinumab) and IL-6 are up-regulated. As you know, it’s been used to treat gout and pericarditis in high doses in short, little bursts.
The change here is this use of low-dose colchicine, that’s 0.5 mg once a day for years to treat chronic, stable atherosclerosis. It is very much like using a statin. The idea here is to prevent the progression of the disease by slowing down and maybe stabilizing the plaque so we have fewer heart attacks and strokes down the road.
It’s entering the armamentarium – at least my armamentarium – as chronic, stable secondary prevention. That’s where the new American College of Cardiology/American Heart Association guidelines also put it. It’s really in as a treatment for chronic, stable atherosclerosis. I think that’s where it belongs.
When to start colchicine, and in whom?
Dr. O’Donoghue: To that point, as we think about the efficacy, I think it’s nice, as you outlined, that we have two complementary trials that are both showing a consistent reduction in MACEs, one in the post–acute coronary syndrome (ACS) state and one for more chronic patients.
At what point do you think would be the appropriate time to start therapy, and who would you be starting it for?
Dr. Ridker: Michelle, that’s a great question. There’s a very interesting analysis that just came out from the LoDoCo2 investigators. It’s kind of a landmark analysis. What they show is that 1 year, 2 years, 3 years, and 4 years since the initiating myocardial infarction, the drug is very effective.
In fact, you could think about starting this drug at your clinic in patients with chronic, stable atherosclerotic disease. That’s just like we would start a statin in people who had a heart attack some time ago, and that’s absolutely fine.
I’m using it for what I call my frequent fliers, those patients who just keep coming back. They’re already on aggressive lipid-lowering therapy. I have them on beta-blockers, aspirin, and all the usual things. I say, look, I can get a large risk reduction by starting them on this drug.
There are a few caveats, Michelle. Like all drugs, colchicine comes with some adverse effects. Most of them are pretty rare, but there are some patients I would not give this drug to, just to be very clear. Colchicine is cleared by the kidney and by the liver. Patients who have severe chronic kidney disease and severe liver disease – this is a no-go for those patients. We should talk about where patients in that realm might want to go.
Then there are some unusual drugs. Colchicine is metabolized by the CYP3A4 and the P-glycoprotein pathway. There are a few drugs, such as ketoconazole, fluconazole, and cyclosporine, that if your primary care doctor or internist is going to start for a short term, you probably want to stop your colchicine for a week or two.
In people with familial Mediterranean fever, for whom colchicine is lifesaving and life-changing and who take it for 20, 30, or 40 years, there’s been no increase in risk for cancer. There have been very few adverse effects. I think it’s interesting that we, who practice in North America, basically never see familial Mediterranean fever. If we were practicing in Lebanon, Israel, or North Africa, this would be a very common therapy that we’d all be extremely familiar with.
Dr. O’Donoghue: To that point, it’s interesting to hear that colchicine was even used by the ancient Greeks and ancient Egyptians. It’s a drug that’s been around for a long time.
In terms of its safety, some people have been talking about the fact that an increase in noncardiovascular death was seen in LoDoCo2. What are your thoughts on that? Is that anything that we should be concerned about?
Colchicine safety and contraindications
Dr. Ridker: First, to set the record straight, a meta-analysis has been done of all-cause mortality in the various colchicine trials, and the hazard ratio is 1.04. I’ll remind you, and all of us know, that the hazard ratios for all-cause mortality in the PCSK9 trials, the bempedoic acid trials, and the ezetimibe trials are also essentially neutral. We’re in a state where we don’t let these trials roll long enough to see benefits necessarily on all-cause mortality. Some of us think we probably should, but that’s just the reality of trials.
One of most interesting things that was part of the FDA review, I suspect, was that there was no specific cause of any of this. It was not like there was a set of particular issues. I suspect that most people think this is probably the play of chance and with time, things will get better.
Again, I do want to emphasize this is not a drug for severe chronic kidney disease and severe liver disease, because those patients will get in trouble with this. The other thing that’s worth knowing is when you start a patient on low-dose colchicine – that’s 0.5 mg/d – there will be some patients who get some short-term gastrointestinal upset. That’s very common when you start colchicine at the much higher doses you might use to treat acute gout or pericarditis. In these trials, the vast majority of patients treated through that, and there were very few episodes long-term. I think it’s generally safe. That’s where we’re at.
Dr. O’Donoghue: Paul, you’ve been a leader, certainly, at looking at CRP as a marker of inflammation. Do you, in your practice, consider CRP levels when making a decision about who is appropriate for this therapy?
Dr. Ridker: That’s another terrific question. I do, because I’m trying to distinguish in my own mind patients who have residual inflammatory risk, in whom the high-sensitivity CRP (hsCRP) level remains high despite being on statins versus those with residual cholesterol risk, in whom I’m really predominantly worried about LDL cholesterol, that I haven’t brought it down far enough.
I do measure it, and if the CRP remains high and the LDL cholesterol is low, to me, that’s residual inflammatory risk and that’s the patient I would target this to. Conversely, if the LDL cholesterol was still, say, above some threshold of 75-100 and I’m worried about that, even if the CRP is low, I’ll probably add a second lipid-lowering drug.
The complexity of this, however, is that CRP was not measured in either LoDoCo2 or COLCOT. That’s mostly because they didn’t have much funding. These trials were done really on a shoestring. They were not sponsored by major pharma at all. We know that the median hsCRP in these trials was probably around 3.5-4 mg/L so I’m pretty comfortable doing that. Others have just advocated giving it to many patients. I must say I like to use biomarkers to think through the biology and who might have the best benefit-to-risk ratio. In my practice, I am doing it that way.