What are biologic drugs and how do they work?

What is a biologic?

A biologic is a drug or vaccine made from a living organism. A biologic can be made from proteins, sugars, DNA, cells or living tissue, for example. The source may be human, animal or a microorganism (like a bacteria or virus).

You might require a biologic product, like gene or protein therapy, to treat diseases such as cancer or arthritis, especially if conventional drugs prove ineffective or if biologics offer better results. Hormones like insulin are also considered biologics. Additionally, biologics can be used as vaccines to prevent diseases, like the vaccine for human papillomavirus (HPV) that helps prevent cervical cancer.

Generally, when people mention “biologics,” they're referring to specialized drug treatments.

What's the difference between a biologic and a conventional drug?

Biologics are different from conventional chemical drugs in several ways.

Biologics activate certain proteins or cells in your immune system to create specific responses to targets, while many conventional systemic drugs activate your entire immune system in a more generalized manner.

• Chemical drugs are small molecules made up of a limited number of atoms. A chemical drug may have dozens of atoms.
• A biologic molecule is much larger and may have thousands of atoms, making them more complex.

Because biologic drugs are so complex:

• The response is less predictable. They may work better for some people than others, and the response may change over time. This may require changing to another biologic.
• They are more difficult to make, and much more expensive. One year of treatment with a biologic may cost well over $100,000. Conventional chemical drugs may have less expensive generic versions that can be used in place of more expensive brand-name drugs. Some biologics also have generic options, but unlike chemical drugs, they are not exactly the same, so they are called biosimilars.
• Most biologics are given by injection or by intravenous (IV) infusion and monitored closely. Because they are usually given by injection or IV, they may cause a reaction at the site of injection or infusion.

Also, because biologic drugs are made from living organisms, they may be more at risk for contamination, so they usually need to be refrigerated.

All biologic drugs and biosimilars must be approved by the Food and Drug Administration (FDA) for safety and effectiveness, just like conventional drugs.

How do different types of biologics work?

Biologics are relatively new drugs that can greatly improve the lives of people with many conditions and diseases. Many biologics are now available, and more are being studied in research trials.

For some people, a biologic may be the only drug that works. Biologics may offer the best treatments for a variety of medical diseases and conditions that have been difficult to treat in the past.

There are several types of biologics that work in different ways:

• Monoclonal antibodies are biologic proteins that can bind to specific proteins in the body or to specific cells.
• Cytokines are biologic proteins that can speed up or slow down your defense system (immune system).
• Growth factor biologics are hormones or chemical messengers in your body that regulate the growth and survival of cells.
• Biologic enzymes are proteins that control chemical reactions, cell signaling and growth.
• Biologic immunomodulators can block or speed up the immune system.

There are dozens of biologics approved to treat many diseases. According to the Congressional Research Service, the top 10 best-selling biologics are:

• Humira (adalimumab), used to treat rheumatoid arthritis, psoriatic arthritis, psoriasis, ulcerative colitis, ankylosing spondylitis (a spinal disease) and uveitis (an eye disease)
• Eliquis (apixaban), used to prevent blood clots
• Revlimid (lenalidomide), used to treat lymphoma and multiple myeloma
• Opdivo (nivolumab), used to treat melanoma skin cancer
• Keytruda (pembrolizumab), used to treat several types of cancer
• Enbrel (etanercept), used to treat psoriasis and rheumatoid arthritis
• Herceptin (trastuzumab), used to treat breast cancer and other cancers
• Avastin (bevacizumab), used to treat colon cancer
• Rituxan (rituximab), used to treat lymphoma, leukemia and rheumatoid arthritis
• Xarelto (rivaroxaban), used to prevent blood clots

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What are the side effects of biologics?

Different biologics have different side effects, but some side effects are common to most biologics. These include an increased risk of infection and both body and skin reactions after receiving the biologic.

• You may be at increased risk for an infection while taking a biologic. Signs of infection include fever, chills, cough or flu-like symptoms. In some cases, the biologic may be stopped until you recover from an infection.
• Injection site reactions usually occur shortly after a biologic injection and can include pain, swelling, redness or itching. These reactions can be treated with a cold compress, an over-the-counter (OTC) antihistamine, and an OTC pain and fever medication. It helps to use a different injection site each time. Over time, these side effects usually go away.
• IV infusion side effects can include reactions at the site of the infusion, similar to injection site reactions. There may also be body reactions — called systemic reactions — like flushing, rash, nausea, chills and headache. More severe reactions are possible, but uncommon. They may include a drop in blood pressure that causes dizziness or fainting, difficulty breathing or chest pain. Treatment may be given to reduce or prevent an infusion reaction before giving a biologic infusion with an antihistamine, anti-nausea or anti-inflammatory medication. After a biologic infusion, patients are instructed to wait under observation to make sure a severe reaction does not occur.

Biologic medications that work by suppressing the immune system can cause a higher risk for colds and other upper respiratory tract infections, as well as worsen an existing, long-term infection, so you may be checked for a long-term infection like tuberculosis, hepatitis or other infectious diseases before you start treatment.

Some biologics have been associated with an increased risk for some types of cancer. In the past, studies have found a slightly increased risk for lymphoma and skin cancer. Because a biologic may affect your immune system, you may be advised not to have certain vaccinations that use a live virus. To date, biologics have not been studied widely during pregnancy or breastfeeding to confirm that they are safe. In cases where there may be a risk from a biologic, that risk must be weighed against the benefits of treatment.

Read next:

• What is a biosimilar drug?
• What are the new drugs for the treatment of plaque psoriasis?
• What biosimilars have been approved in the United States?