Biological response modifiers are the newest class of drugs for the treatment of rheumatoid arthritis (RA). These modern “biologics” have greatly improved the effectiveness of treatment for many RA patients. Unlike older disease-modifying anti-rheumatic drugs (DMARDs), biologic DMARDs are made using biotechnology. They are genetically engineered to behave like natural immune system proteins.
People who don’t respond to older drugs like methotrexate may benefit from treatment with a biologic drug. Sometimes biologics may be given alone. They may also be administered in combination with another type of drug. The combination of methotrexate and a biologic drug is effective for most RA patients. Experts recommend that patients diagnosed with RA should be started on drug therapy as soon as possible to combat joint damage. The older DMARD, methotrexate, is often the first drug prescribed. A biologic drug may be prescribed if methotrexate fails to control symptoms adequately.
How Are They Given?
Most biologics are given by injection. Some are injected under the skin, while others must be injected directly into a vein. One medication, tofacitinib citrate (Xeljanz), is available as a pill taken orally. Biologics provide relief to some patients who do not respond to older drugs. They also have the advantage of fewer side effects. They’re not completely free of side effects, however.
Biologics work by interrupting immune system signals involved in the damage of joint tissue. Many newer drugs target a protein called tumor-necrosis factor (TNF). These drugs are called anti-TNF biologics. Like other DMARDs, biologics affect immune system function. Because of this, they can make a person more susceptible to serious infections. Infections affecting the airways are particularly common. There is also an increased risk of liver damage. The body’s ability to produce new blood cells could also be affected.
Biologics work for more patients because they target specific aspects of the immune system to reduce inflammation in the joints. Any drug that suppresses the immune system carries risks, though. It is important to tell your doctor about any unusual symptoms you experience, such as fever or other symptoms that are not easily explained. For instance, some people may have a dormant infection that can become active after starting biologic therapy. For this reason, it’s important to have a tuberculosis test before taking one of these drugs. People with liver disease may not be eligible to take a biologic drug.
Biologic DMARDs available now include: tocilizumab (Actemra), certolizumab (Cimzia), etanercept (Enbrel), adalimumab (Humira), anakinra (Kineret), abatacept (Orencia), infliximab (Remicade), rituximab (Rituxan), golimumab (Simponi), and tofacitinib (Xeljanz). More new biologics are undergoing testing and may be available soon.
Some of these drugs take effect fairly quickly. Others may require weeks or months to fully take effect. Each patient is different, so response time can be unpredictable. Not all patients respond to a given drug. Some may be able to take a biologic alone, but many will receive a biologic drug plus an older drug like methotrexate.
The advent of biologic drugs for RA treatment has allowed experts to better understand the complex processes underlying the disease. Although these drugs do not cure RA, they can dramatically slow its progression. One day, scientists hope to find a treatment that will completely cure the disease.
Specific Types of Biologics
Older DMARDs work by suppressing the immune system in a general fashion. Biologics are sometimes better at controlling RA progression because they target specific mediators of RA inflammation. Modern biologic drugs for RA can be categorized by the way they work in the body.
Abatacept works by crippling a type of white blood cells called T cells. T cells play a role in promoting the inflammation that causes RA.
Many biologics work by interfering with the activity of tumor necrosis factor, a key immune system protein. Among these are adalimumab, etanercept, infliximab, and golimumab.
Rituximab appears to help control RA by destroying another category of immune system cells called B cells. Its activity in the body is complex. These actions are not yet fully understood.
Anakinra blocks the action of an immune system protein called interleukin-1 (IL-1). IL-1 is often called a master cytokine, because it regulates local and systemic inflammation in the body.
Tofacitinib is in a new class by itself. It’s called a Janus-associated kinase (JAK) inhibitor. It works by inhibiting a cellular signaling pathway inside cells. This prevents the production of components that promote inflammation. Older biologics block inflammation from the outside of cells, but JAK-inhibitors work within cells. This is the only biologic that is not injected. It is available as a pill, taken twice a day.
Virtually all drugs carry possible side effects. Biologics for the treatment of RA are no different. As seen above, biologics work in a number of different ways to reduce inflammation. They all interfere with some aspect of immune system function, though. For this reason, people taking a biologic drug may be at greater risk for certain infections.
Before beginning biologic therapy, it’s important to tell your doctor if you have had an infection, fever, lung disease, or tuberculosis infection. Report any unusual symptoms to your doctor. Pain or swelling at the injection site are not uncommon for drugs given by injection. Some common side effects, such as nausea, may get better over time. Taking a drug with meals may help control nausea.