Stopping osteoarthritis: Could recent heart research provide a clue?

Here’s a recent headline that I found confusing: Could the first drug that slows arthritis be here?

It’s confusing because it depends on which of the more than 100 types of arthritis we’re discussing. We’ve had drugs that slow rheumatoid arthritis for decades. In fact, more than a dozen FDA-approved drugs can reduce, or even halt, joint damage in people with rheumatoid arthritis. We also have effective medications to slow or stop gout, another common type of arthritis.

But the headline refers to osteoarthritis, the most common type of arthritis. And currently, no medications can safely and reliably slow the pace of this worsening joint disease. That’s one reason so many knee and hip replacements are performed: more than 1.2 million each year in the US alone.

A drug that can slow down joint degeneration in osteoarthritis has long been the holy grail of arthritis treatments, because it could

• relieve pain and lessen suffering for millions of people
• help prevent the loss of function that accompanies osteoarthritis
• reduce the need for surgery, along with its attendant risks, expense, and time needed for recovery.

And, needless to say, such a drug would generate enormous profits for the pharmaceutical company that comes up with it first.

A study of heart disease might have identified a new treatment for osteoarthritis

According to new research published in Annals of Internal Medicine, it’s possible that such a treatment exists, and is already in use to treat other conditions. The researchers reanalyzed data on more than 10,000 people that originally looked at whether the drug canakinumab was beneficial for people with a previous heart attack — yes, heart attack, not arthritis.

Canakinumab inhibits interleukin-1, a substance closely involved with inflammation. And increasing evidence suggests that inflammation raises risk for cardiovascular disease, and may predict future cardiovascular trouble. All study participants had previously had a heart attack. Additionally, they had an elevated blood C-reactive protein (CRP) level, an indicator of inflammation in the body.

Every three months, each person received an injection of one of several doses of either canakinumab or a placebo. Canakinumab appeared to work for heart disease: those receiving the 150-mg dose of canakinumab had significantly fewer cardiovascular complications (repeat heart attack, stroke, or cardiovascular death) over about four years. Unfortunately, there was also a higher rate of fatal infections in the canakinumab-treated subjects.

Another look at this study of canakinumab

The reanalysis compares rates of hip or knee replacement due to osteoarthritis in those receiving canakinumab with rates among those who received a placebo. The study authors thought that since canakinumab reduces inflammation, it might help the inflammation found in the joints of people with osteoarthritis while also offering cardiovascular benefits.

Osteoarthritis has long been considered a wear-and-tear, age-related, and non-inflammatory form of joint disease. But over the last decade or so, research has demonstrated that some degree of inflammation occurs in osteoarthritis. So it’s not too much of a stretch to think a drug like canakinumab might be effective for osteoarthritis. This drug is already approved for a number of inflammatory conditions, including certain forms of pediatric arthritis.

The results of this new study surprised me: over about four years, those receiving canakinumab were at least 40% less likely to have a hip or knee replacement than those receiving placebo.

Warning: These results are preliminary

Before declaring victory over osteoarthritis with canakinumab treatment, it’s important to acknowledge that this trial doesn’t prove it actually works. That’s because the trial

• was not a treatment trial of people with osteoarthritis. More than 80% of participants had no history of osteoarthritis.
• did not compare x-rays or other imaging tests before and after treatment to confirm the diagnosis of osteoarthritis, or demonstrate that treatment slowed its progression
• did not assess whether joint pain was present before treatment or improved after treatment. It’s possible that the reason there were fewer joint replacements among people taking canakinumab is that the medication reduced pain, rather than slowing joint damage. Perhaps the medication can delay the need for joint replacement by reducing symptoms without slowing progression of joint damage.
• lasted about four years. The results could have been different if it had lasted longer.
• only included people who had prior heart attack and an elevated CRP. The results may not apply to people who have no history of cardiovascular problems or a normal CRP.

To learn whether canakinumab actually can slow osteoarthritis, we need a proper trial that enrolls people with osteoarthritis, and compares symptoms and x-rays after treatment with canakinumab or placebo.

Canakinumab is expensive, nearly $70,000/year (though discounts, insurance coverage, and copays vary), and only available by injection. It’s not clear how many people with osteoarthritis would accept such treatment. If it is proven highly effective at preventing the need for joint replacement surgery, its high cost might be easier to accept.

The bottom line

We need definitive information about the potential of canakinumab or related drugs to treat osteoarthritis and slow its progression. Until then, it’s unlikely to become a common option.

If you have osteoarthritis of the knees or hips, talk to your doctor about your options, including maintaining a heathy weight, staying active, and taking pain relievers as needed. Some people improve with walking aids (such as a cane) or knee braces (for knee arthritis). Joint replacement surgery can be considered as a last resort.

As for new treatments that can slow the progression of osteoarthritis, we should be hopeful. But we’re not there yet.

Follow me on Twitter @RobShmerling

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