Psoriatic arthritis (PsA) is a chronic form of inflammatory arthritis that causes stiff and painful joints. It affects between 5 and 10% of people who have psoriasis, although some estimates put that number as high as 30%. In severe cases, PsA can be quite debilitating, preventing people from being able to carry out their normal activities of daily living. That can have a pretty significant impact on quality of life, making an effective treatment a “must-have.” Many experts consider biologic treatments to be a breakthrough in helping people with psoriatic arthritis manage their condition and feel better.
What’s a biologic drug?
If your doctor tells you she’s recommending a biologic drug to treat your psoriatic arthritis, would you know what that means? You might suspect from the name that a biologic, or biological drug, is a drug that has its origins in living cells or tissues. And you’d be right. So, if your doctor prescribes a biologic for you, the doctor is recommending a type of drug that has been genetically engineered from living material. Biological products span a wide variety of products, including vaccines, blood components and recombinant therapeutic proteins, among others, according to the U.S. Food and Drug Administration. Biologic drugs are used to treat a number of different conditions, including autoimmune conditions like Crohn’s disease, ulcerative colitis and multiple sclerosis. Biologics are also increasingly used to treat certain rheumatic diseases, including psoriatic arthritis. “It’s become very common nowadays because the biologics are so effective both for the skin and the joint disease,” says Fotios Koumpouras, MD, assistant professor of medicine at the Yale School of Medicine.
Biologics as a targeted approach
Psoriatic arthritis is considered to be a progressive disease. Left untreated, it will get worse over time. That means your joints may very well become increasingly inflamed, swollen and painful, and you may sustain irreversible damage to them. To stop that from happening, you need treatment. That typically involves a disease-modifying antirheumatic drug (DMARD). There are two types of DMARD: non-biologics and biologics. Non-biologic treatments include methotrexate, which is the most commonly prescribed non-biologic DMARD for psoriatic arthritis, according to the Cleveland Clinic. Before biologics came along, many doctors prescribed methotrexate, sometimes with non-steroidal anti-inflammatory drugs (NSAIDS) or corticosteroids to address the pain. And many doctors still opt to begin with this type of treatment. Elaine Husni, MD, MPH, a rheumatologist with the Cleveland Clinic, explains that she might offer a patient with mild psoriatic arthritis the opportunity to start with methotrexate, although she also takes other factors into account. Meanwhile, she might be more inclined to recommend a biologic to a patient with a more severe, progressing form of psoriatic arthritis—or to a patient who has tried and failed to achieve success with conventional treatment. Biologics modify your body’s immune system in a specific way to keep it from attacking itself, explains Raj Bhatt, MD, a rheumatologist with PRIME Rheumatology PLLC in Texas. Think: targeted approach vs. broad approach. Brett Smith, DO, compares a biologic drug to a conventional drug in this way: imagine that you have a target in front of you. You have two options for hitting the center of the target: a can of paint, which is a conventional treatment, and a bow and arrow, which is a biologic. Which do you pick? If you want the more targeted approach, you go with the biologic. “They really just work better,” says Dr. Smith, a rheumatologist in Knoxville, Tennessee.
What biologic options are used to treat psoriatic arthritis
Since biologics came along, many doctors have increasingly turned to them to help their patients with psoriatic arthritis. Unlike methotrexate, which is taken orally, biologics are typically given by injection or infusion. The main types of biologic drugs used to treat psoriatic arthritis include:
TNF inhibitors. Tumor necrosis factor inhibitors, or tumor necrosis factor-alpha inhibitors, target a specific protein known as TNF-alpha. TNF-alpha is a cytokine that provokes your body into creating inflammation in your joints or skin. So, this type of biologic blocks the production of that cytokine, lessening the inflammation and the pain and swelling it tends to create.
Examples include infliximab (Remicade), adalimumab (Humira) and etanercept (Enbrel).
Interleukin inhibitors. Interleukin inhibitors are monoclonal antibodies that work by targeting the action of a type of cytokine known as interleukin. Think of interleukin as a driver of inflammation. There are several different kinds of interleukin molecules that can produce inflammation in your body, albeit in slightly different ways. So, there are also several different kinds of interleukin inhibitor medications that are used in the treatment of psoriatic arthritis. For example, you have interleukin-17 (IL-17) inhibitors, which focus in on the interleukin-17 molecule, which provokes the production of cytokines like those TNF-alpha cytokines, which leads to, you guessed it, inflammation. The list also includes drugs that target the interleukin-12 (IL-12) and interleukin-23 (IL-23) molecules and drugs that target the interleukin-23 (IL-23) molecule.
Examples include the IL-17 inhibitors ixekizumab (Taltz), brodalumab (Siliq), secukinumab (Cosentyx); ustekinumab (Stelara), which is an IL-12/IL-23 inhibitor; and IL-23 inhibitors such as guselkumab (Tremfya).
T-cell co-stimulation modulators. The t-cell co-stimulation modulator abatacept was first approved by the U.S. Food and Drug Administration to treat moderate to severe rheumatoid arthritis, but it was later approved to also treat psoriatic arthritis. This type of drug, also known as a selective co-stimulation modulator, is different from the other biologics in that it doesn’t actually block inflammatory proteins, according to the American College of Rheumatology. Instead, it targets a type of immune cell known as T-lymphocyte, or T-cell. In fact, the drug attaches to the surface of those T-cells, and in doing so, prevents them from communicating with each other. When they don’t communicate with each other, they can’t set off the cascade of inflammation that causes joint pain, swelling and damage.
Example: abatacept (Orencia) Your doctor will consider a number of factors when recommending a biologic for you, including how serious your disease is and any other health conditions you may have. According to Dr. Husni, it’s also important to consider whether your skin or your joints are more affected. Biologics can address both conditions, but some are considered more effective than others for certain situations. For example, if you have numerous swollen and painful joints, but you only have one, or maybe two, psoriasis plaques on your skin, you might be a good candidate for a TNF-alpha inhibitor. But if you have psoriasis plaques on over half of your body but you only have minimal joint involvement, an IL-17 inhibitor could be a possible option.
What’s a biosimilar?
You might be looking at the name of a biologic drug and realize that it’s not quite the same as the one listed on your prescription. In that case, you may be using a biosimilar. Biosimilars are medicines that are very similar to–but not exactly the same as–biologics in function and structure. According to the FDA, they are safe, effective treatments that are designed to be interchangeable with an FDA-approved biologic treatment. That is, they may be slightly different, but the differences are not “clinically meaningful.” Here’s an example: you may have a prescription for a medication with the brand name Inflectra (infliximab-dyyb). Inflectra is a biosimilar to Remicade (infliximab) that was approved by the FDA in 2016. Remicade is considered the reference drug or product for Inflectra. Dr. Koumpouras notes that sometimes physicians prescribe biosimilars to help patients save on costs, since biologics are often expensive. “We hope that this further expands access to these very important and powerful medicines,” he says. Next, Creaky Joints and Red Skin? Learn About the 5 Types of Psoriatic Arthritis + Treatments
Sources:
—Raj Bhatt, MD, a rheumatologist with PRIME Rheumatology PLLC in Texas. —Elaine Husni, MD, MPH, a rheumatologist with the Cleveland Clinic. —Fotios Koumpouras, MD, assistant professor of medicine at the Yale School of Medicine. —Brett Smith, DO, a rheumatologist in Knoxville, Tennessee. —Arthritis Foundation: Biologics. —Arthritis Foundation. FDA OKs Biologic for Psoriatic Arthritis. —Habashy, Jacquiline. Which medications in the drug class Interleukin Inhibitors are used in the treatment of Psoriasis? Medscape. —Li, H, et al. Phosphodiesterase-4 Inhibitors for the Treatment of Inflammatory Diseases. Frontiers in Pharmacology. —Mayo Clinic: Psoriatic Arthritis. —Monoclonal antibodies inhibiting IL-12, -23, and -17 for the treatment of psoriasis. Human Vaccines and Immunotherapeutics. —National Psoriasis Foundation: Biologics. —Ogdie, Axis and Weiss, Pamela. The Epidemiology Psoriatic Arthritis. —Ronholt, Kirsten and Iversen Lars. Old and New Biological Therapies for Psoriasis. International Journal of Molecular Sciences. —U.S. Food and Drug Administration. Biosimilars. —U.S. Food and Drug Administration. Biosimilar and Interchangeable Products. —U.S. Food and Drug Administration: What Are “Biologics” Questions and Answers. —U.S. National Library of Medicine. Psoriatic Arthritis.
