Considering the Long-Term Safety of Biologics

As a chronic condition, psoriatic arthritis (PsA) requires ongoing treatment, and some in our community have asked about the long-term safety of biologics. Biologics are medications that have been genetically engineered to act on specific targets in the immune system. Unlike their predecessors, immunosuppressants, which have an overall suppressing effect on the immune system, biologics create less interference with other functions by focusing on specific pathways or compounds. Because of their targeting capabilities, biologics are used in the treatment in autoimmune diseases like PsA, plaque psoriasis, rheumatoid arthritis, and inflammatory bowel disease.

However, like all medications, biologics can cause unwanted side effects. While each medication is unique and has its own potential side effects, common side effects of biologics include an increased risk of infections (bacterial, viral, and fungal) and injection site reactions (redness, pain, and/or swelling of the area where the injection is given). Sometimes, the infections people taking biologics develop can be serious or life-threatening, and some people experience severe allergic reactions to biologics. Rarely, less common side effects can occur with biologic medications like central nervous system disorders (vision problems, numbness, or tingling), cardiac issues (worsening or sudden onset of heart failure, which may appear as shortness of breath or sudden swelling of the hands or ankles), or Lupus-like syndrome (a rash that affects the face and arms and worsens in the sunlight, and joint or body pain).¹

Are the risks of getting cancer higher when you’re on a biologic?

Because of the key role that the immune system plays in the defense against cancer in the body, there has been concern about the risk of cancer with treatment with biologics. In particular, there is worry that by inhibiting tumor necrosis factor (TNF), you may be stopping the natural action of this compound to stop cancers. While TNF got its name for one of its actions, the name was established before its full role was completely understood. TNF actually has multiple functions and is well-known as a promoter of inflammation and is actively involved in the pathogenesis of many autoimmune diseases. Chronic inflammation by itself can increase the likelihood of cancer. Another activity of TNF is its effect on angiogenesis, which is the development of new blood vessels – an activity that is critical for tumor growth, survival, and metastasis (spread). Some researchers believe that the use of TNF inhibitors may actually decrease the risk of some cancers, by reducing angiogenesis and suppressing inflammation.²

One autoimmune disease that has an increased risk of lymphoma (a type of blood cancer that affects the lymphatic system) is rheumatoid arthritis (RA). People with RA have a greater risk of developing lymphoma than the general population. A meta-analysis (review of several clinical trials) of TNF inhibitors in people with RA found little to no cancer risk associated with the medications.⁴ More recently, a British study that evaluated over 20,000 people with RA (some on a biologic and others on another disease-modifying treatment) found that there was no additional risk for lymphoma for the group receiving a TNF inhibitor.³

Another study looked at people with RA who had a previous cancer before starting treatment with either a TNF inhibitor or Rituxan (rituximab). The data suggested that treatment with a TNF inhibitor did not increase the risk of a future cancer.⁴

What about cancer risk with biologics in psoriatic arthritis?

A 2014 study that compared the rates of cancer among people with PsA and people with RA found that the incidence of cancer was similar among the two patient groups. The most common cancer in both groups was non-melanoma skin cancers.⁵

Another study from 2016 compared the rates of cancers and opportunistic infections among people with PsA and people without PsA. While rates of cancer increased in both groups with older age, the PsA group had a slightly higher rate of blood cancers. Rates of solid tumors (like breast, colon, and lung cancer) and non-melanoma skin cancers were similar between the two groups. The PsA group also had a higher rate of opportunistic infections than the group who didn’t have PsA. In addition, the researchers compared those on prescription medicines for PsA to those with PsA who were not taking any prescription medicines. Rates of solid cancers and blood cancers were higher in the group who took prescription medicines. However, those on biologic DMARDs had the lowest rates of these cancers.⁶

How long does a biologic stay in your system after you stop taking it?

While there’s no single or easy answer to how long a biologic stays in the body after treatment is stopped, there is some data available that can provide some clues. For example, in the prescribing information for Humira^® (adalimumab), the half-life of the medication is stated as approximately two weeks, ranging from 10 to 20 days across studies.⁷ (Half-life is the time it takes for the body to reduce the amount of the dose by half.) Furthermore, one study on people with psoriatic arthritis who stopped biologic treatment analyzed how long it took for symptoms to return and found that the median time it took for symptoms to return was eight months.⁸

It’s worth noting that the time it takes for a medication to completely pass through a person’s body is going to be unique to the individual, as this can be affected by an individual’s metabolism and overall health.

What does this mean for me?

While the data suggests that, in general, long-term biologic therapy is an effective and safe treatment for the treatment of PsA, data alone does not help with individual treatment decisions. Each person must weigh the risks and benefits with their healthcare professional, taking into consideration their unique health concerns, their family history, other conditions they may have, and other medications or supplements they are currently taking.