Biologics are a type of medication made from living organisms. They typically include synthetic proteins designed to replicate the functions of naturally occurring ones that play a role in the immune system. Biologics can provide an effective, generally safe treatment for ankylosing spondylitis (AS).

There is currently no cure for AS, but biologics can help a person better manage their symptoms.

Some people may refer to these drugs as biopharmaceuticals or biologic medical products. Although they are often expensive, they can help reduce symptom severity and prevent disease progression.

This article discusses what biologics are, how they work, and who should potentially avoid them.

The immune system is a complex structure comprising cells, proteins, and organs that work together to help keep the body healthy.

In the case of AS, the immune system mistakenly attacks healthy cells and produces inflammation. Scientists have found that two types of proteins — interleukin (IL) and tumor necrosis factor (TNF) — play a significant role in producing inflammation in the body.

Biologics work by blocking receptors for these two protein types, thereby preventing the immune system’s inflammatory response. By doing this, they reduce AS symptoms, help prevent damage to the joints, and lessen the likelihood of further complications associated with AS.

Currently, there are three main types of biologics that doctors use in AS management:

  • TNF inhibitors
  • IL-17 inhibitors
  • IL-12/23 inhibitors

Dr. Robert Koval, a board certified rheumatologist with Texas Orthopedics in Austin, TX, told Medical News Today that he recommends biologics either when people do not respond well to initial treatment options or when they start to develop new symptoms in spite of their treatment.

His goal when using biologics is for the person to achieve “complete resolution of symptoms.”

TNF inhibitors

According to the Spondylitis Association of America, TNF inhibitors were the first type of biologics that the Food and Drug Administration (FDA) approved for the treatment of AS. TNF inhibitors have shown effectiveness in treating inflammation in several areas of the body, including the:

  • joints
  • gut
  • eyes

There are currently five different TNF inhibitors that a doctor may recommend. They are:

  • infliximab (Remicade)
  • adalimumab (Humira)
  • etanercept (Enbrel)
  • certolizumab pegol (Cimzia)
  • golimumab (Simponi)

Although all TNF inhibitors target TNF — a cytokine that is responsible for signaling the immune system’s inflammatory response — they each operate slightly differently. Due to this, if a person develops resistance to one type, their doctor can switch them to a different type.

However, according to Dr. Koval, many people can stay on the same medication indefinitely.

IL-17 and IL-12/23 inhibitors

IL-17 and IL-12/23 inhibitors operate in a similar fashion to block cytokines, which prevents the immune system from producing an inflammatory response. IL-17 inhibitors block the IL-17 cytokine, and IL-12/23 inhibitors block both the IL-12 and IL-23 cytokines.

Currently, there are two types of IL-17 inhibitors: ixekizumab (Taltz) and secukinumab (Cosentyx).

However, the FDA has only approved one type of IL-12/23 inhibitor, called ustekinumab (Stelara), for treating AS.

It is possible to administer biologics in the form of injections or IV infusions.

The method of delivery will depend on the specific medication that the doctor prescribes. If the drug is available as an injection, a doctor can often prescribe it for the person to self-administer at home. However, a person will need to visit the doctor’s office, infusion center, or hospital to get an infusion.

Studies have shown that people generally tolerate biologics well. However, this line of treatment can sometimes cause unpleasant side effects.

The Arthritis Foundation notes that common side effects of biologics may include:

  • an increased risk of infection
  • a reaction at the injection site, which may involve swelling, itching, or pain
  • a reaction to the infusion, which can produce symptoms such as headaches, nausea, and pain

A person should watch for new and changing symptoms that may indicate the development of an infection or another side effect. If they experience a side effect, they should let their doctor know.

Biologics can cause complications in some people, and certain medications may interact with them. As a result, biologics may not be suitable for everyone.

Certain groups of people should avoid taking biologics or take extra care when doing so because of possible complications or adverse reactions. Some considerations or general guidelines include:

  • People who are pregnant or breastfeeding should check with a doctor before using biologics, but these should be safe for them in most cases.
  • Anyone using biologics should avoid immunizations that use live vaccines.
  • Individuals receiving cancer, diabetes, heart, or nervous system treatment should talk with a doctor before using biologics.

The use of biologics also comes with an increased risk of developing or having a recurrence of infections, including hepatitis B or C and tuberculosis.

In addition, some evidence suggests that TNF inhibitors can lead to an increased risk of a person developing cancer, particularly lymphoma.

However, research has shown that biologics have an overall good safety record and that most people tolerate them well. A 2021 report analyzing 48 studies on the adverse effects of anti-IL-23 treatments did not identify any links between these medications and increased cancer risk.

A person should talk with a doctor if they are concerned that they have a higher risk of complications. Likewise, a person using biologics to treat their AS should communicate with a doctor about any adverse reactions.

Biologics are an effective and often well-tolerated treatment option for people living with moderate-to-severe AS. Biologics work by targeting the protein receptors in the immune system to prevent the immune response that creates inflammation.

Although biologics are generally safe, a person should let a doctor know if they experience adverse reactions. People concerned about their risk factors for developing complications should discuss these worries with a doctor.