Ankylosing spondylitis (AS) is a chronic autoimmune disease. The condition often affects the lower back and pelvic areas, but it can also affect other joints, organs, and tissues. If a person living with AS finds their current treatment ineffective, they may wish to consider switching treatments.

The standard treatment for AS is nonsteroidal anti-inflammatory drugs (NSAIDs). If these do not work, doctors often turn to a type of biologic called tumor necrosis factor (TNF) inhibitors.

Biologics are a type of medication made from living organisms. They replicate proteins that occur naturally in the body. Doctors use them to help people with AS manage their symptoms and slow the progression of the disease.

Although some people may remain on the same biologic medication for years, others may need to switch to a different type if their symptoms return.

This article reviews what people need to know about switching treatments for AS.

Doctors use biologics to help relieve AS-associated symptoms.

Dr. Robert Koval, a board certified rheumatologist with Texas Orthopedics in Austin, told Medical News Today that biologics work better than disease-modifying antirheumatic drugs (DMARDs) in the treatment of AS. He uses DMARDs for milder symptoms, which often affect the joints of the arms or legs.

He added: “Biologics work much better for axial or spinal disease. They prevent damage, in addition to controlling the symptoms.”

According to the Spondylitis Association of America, three approved types of biologics are available for treatment:

  • TNF-alpha inhibitors: The Food and Drug Administration (FDA) approved the first TNF inhibitor in 2003. These medications can effectively treat joint pain and general inflammation that affects the eyes and gastrointestinal tract.
  • Interleukin-17 (IL-17) inhibitors: Another form of biologics, IL-17 inhibitors help reduce overall inflammation and calm the immune system’s response.
  • IL-12/23 inhibitors: As with IL-17, these medications work to reduce overall inflammation and minimize the immune system’s response. However, they target slightly different receptors in the body.

Currently, the FDA has approved five different TNF inhibitors, two IL-17 inhibitors, and one IL-12/23 inhibitor for use in the treatment of AS. As a result, doctors have several options if the person experiences unpleasant side effects with one type or their symptoms return.

It is important to note that while biologics may prove effective, side effects are possible. These drugs can also make a person more susceptible to infections, as they lower the immune system response. A person should talk with a doctor about the potential side effects and weigh them against the benefits.

In most cases, doctors start with medications such as NSAIDs when treating people with AS who have only mild symptoms. If these symptoms worsen, a doctor may recommend switching to biologics.

Dr. Koval noted that for some individuals, “biologics will work indefinitely, and many patients will never have to change [biologics].”

However, others may need to try another biologic if the initially prescribed biologic causes severe side effects or does not manage the symptoms of the disease. According to a 2019 study, about half of all people who start their first TNF inhibitor switch within 5 years, often to another form of the medication.

Why do it?

Dr. Koval said that there are a few reasons why he might switch a person’s biologics. These include:

  • The treatment is not allowing the person to achieve complete remission.
  • Unpleasant side effects, such as headaches and flu-like symptoms, are occurring.
  • Over time, the particular biologic stops working well, and the symptoms return.

His goal in treatment is “always to get the patient into remission, basically feeling like they did before the disease began. With multiple options out there, we are never satisfied until the patient has a complete resolution of symptoms and feels great.”

Are biologics less effective over time?

As Dr. Koval noted, biologics can lose their effectiveness over time. Sometimes, people develop resistance to a particular biologic, but when they switch, they can often achieve the same results they had before.

A 2016 review of 14 studies, which included a total of 2,672 people living with AS, also supports switching drugs if necessary. The researchers note no difference in effectiveness among the various forms of biologics available for AS, with the exception of infliximab being slightly more effective. The study implies that a person may be able to switch biologics if they develop resistance to one or develop side effects.

Are biologics more effective than DMARDs?

DMARDs have a limited role in the treatment of AS. According to the Global Healthy Living Foundation, doctors typically recommend DMARDs for AS with peripheral involvement — meaning that the disease affects the knees, ankles, hips, or arms — when NSAIDs are not effective. They do not recommend them when the symptoms are in the spine or neck.

Dr. Koval shares similar views, and he stated: “Biologics certainly work better than DMARDs in ankylosing spondylitis. DMARDs are reserved for milder symptoms, usually in the peripheral joints.”

He went on to say: “Biologics work much better for axial or spinal disease. They prevent damage, in addition to controlling the symptoms.”

A doctor will likely recommend the use of biologics if a person has spine and neck involvement and more severe symptoms. At times, a person may develop side effects from or resistance to a particular biologic. A doctor can often switch biologics to one that works better for the person.

For mild symptoms that do not affect the spine or neck, a doctor may not recommend biologics. Instead, they might suggest NSAIDs, DMARDs, or other medications to help control the symptoms. If the symptoms worsen, a doctor will then suggest switching to biologics.