Relief for the pain and stiffness of ankylosing spondylitis often starts with nonsteroidal anti-inflammatory drugs (NSAIDs) and then biologics, but it doesn't always end there. If these medicines don't help enough or you can't take them for one reason or another, the next step might be to try a janus kinase (JAK) inhibitor.
Like biologic drugs, JAK inhibitors slow joint damage. But unlike the biologics, they come in a pill so you can avoid the needle.
What Are JAK Inhibitors?
JAK inhibitors are a newer addition to ankylosing spondylitis treatment. Like biologics, they're part of a group of medicines called disease-modifying antirheumatic drugs (DMARDs). They get the name "disease-modifying" because they slow the progression of damage in the spine and other joints.
Ankylosing spondylitis isn't the only autoimmune disease that JAK inhibitors treat. They're also approved for:
- Rheumatoid arthritis
- Polyarticular course juvenile idiopathic arthritis
- Psoriatic arthritis
- Ulcerative colitis
What Types Are Used for Ankylosing Spondylitis?
Two JAK inhibitors are approved to treat ankylosing spondylitis:
They're approved for people who tried one or more biologic drugs called TNF inhibitors but didn't improve on them or had side effects they couldn't tolerate.
How Do JAK Inhibitors Work?
JAK inhibitors target a group of enzymes – proteins that are involved in your body's chemical reactions. These enzymes help to send the signals that tell immune cells to make inflammatory chemicals called cytokines, which lead to damage.
These medicines work differently than biologic drugs. Each biologic drug targets a specific cytokine that causes joint inflammation, like tumor necrosis factor (TNF) or interleukin-17 (IL-17). JAK inhibitors block many cytokines at once.
Who Can They Help?
NSAIDs are usually the first treatment doctors recommend for ankylosing spondylitis. If NSAIDs don't help, then the next option would be to take a TNF inhibitor or possibly an IL-17 inhibitor. But close to 1 in 3 people don't get enough improvement on these medicines. Others can't take biologics because of the side effects or their other medical conditions.
A JAK inhibitor might be right for you if:
- NSAIDs didn't help enough with your symptoms.
- You didn't improve while taking a TNF inhibitor.
- You couldn't take a TNF inhibitor because of the side effects.
How Do You Take Them?
JAK inhibitors come as pills. The dose for Rinvoq is one 15-milligram pill, once a day. Xeljanz comes in two types: a 5-milligram tablet that you take twice a day, or an 11-milligram extended-release tablet you take once a day.
You can take these medicines with or without food.
How Well Do They Work?
Studies have shown that JAK inhibitors are more helpful for pain, inflammation, and other symptoms of ankylosing spondylitis than a placebo.
In a study of 269 people with ankylosing spondylitis, 56% of people who took 5 milligrams of Xeljanz twice a day for 4 months had a 20% or more improvement in their symptoms and ability to function, compared to less than 30% of people who took a placebo. More people in the Xeljanz group reported a 40% improvement compared to the placebo group.
A study of Rinvoq also showed promising results. After taking 15 milligrams of the drug daily for 14 weeks, 52% of people had a 40% improvement. Only 26% of people who took a placebo improved.
What If I Have Non-Radiographic Ankylosing Spondylitis?
Axial spondylitis comes in two types:
- Axial spondylitis (AS)
- Non-radiological axial spondylitis (nr-axSpA)
Non-radiological means your X-rays don't show clear signs of damage from ankylosing spondylitis. It's sometimes thought of as an early stage of the disease, although not everyone who has nr-axSpA will progress to full-blown ankylosing spondylitis.
JAK inhibitors aren't approved specifically for nr-axSpA, but they may be helpful. Research shows that a 15-milligram daily dose of Rinvoq improves pain, function, quality of life, and disease activity better than a placebo.
Possible Side Effects
Overall these medicines are safe, but they do have a few risks. The most common side effects with JAK inhibitors are:
- Colds and other mild upper respiratory tract infections
Some people have changes on their blood tests like:
- Low white blood cells or red blood cells
- Changes in cholesterol levels
- Damage to the kidneys or liver
Your doctor will do regular blood tests to monitor you for these and other problems while you take a JAK inhibitor.
Both of these medicines carry a boxed warning – the strongest warning label – because they can cause rare but serious risks like these:
- Infections like tuberculosis (TB)
- Blood clots, heart attack, and stroke
- Lymphoma and other cancers
JAK inhibitors work by lowering your immune system response to stop it from attacking your joints. A weaker immune system is also less effective at fighting bacteria, viruses, and other germs.
Before you start taking a JAK inhibitor, your doctor will test you for TB. After you've been exposed to TB, the bacteria that cause this infection can live in your body without making you sick. The name for this is latent TB. A JAK inhibitor could wake up a latent virus and make it active.
Your doctor will test you again during treatment. If you get TB while taking a JAK inhibitor, you may have to stop the drug and get treatment to clear the infection.
You should avoid live vaccines while you take a JAK inhibitor. The measles, mumps, rubella (MMR), rotavirus, and smallpox vaccines are examples of live vaccines. They contain live but weakened versions of these viruses. These vaccines could make you sick if a JAK inhibitor has weakened your immune system.
What to Expect
Your symptoms could start to improve as soon as 2 weeks after you go on a JAK inhibitor. But it could take as long as 6 months for you to see the full effect.
Everyone responds to medications differently. If you don't see any improvement after a few months of taking one of these drugs, ask your doctor for advice on next steps.