How Biologic Therapy Works

Differences Between Biologic Treatments and Traditional Pharmaceutical Drugs

Biologic therapy comes in many forms including vaccines, therapeutic proteins, and monoclonal antibodies. Other terms for this therapy include “biologics,” “biological therapy,” “biologicals,” and “biopharmaceuticals.” You might also hear biologic medicines called by their over-the-counter names or referred to as a specific subcategory of biologic therapies (e.g., gene therapy).

Biologic medicines are different from most pharmaceutical drugs. They are made from a living organism instead of chemical compounds. Each biologic therapy works slightly differently. These products can treat, and sometimes cure, a wide range of diseases, including skin conditions, autoimmune diseases, chronic bowel diseases, and cancer.

This article will explain what biologic therapy is and what types are available. Using examples, it will show how biologics work, what conditions they can treat, and what side effects and risks can be expected. It will also explain what biosimilars are and how they compare with biologics.

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What Is Biologic Therapy?

Biologic therapy refers to any type of medical therapy that is derived from living organisms such as humans, animals, or microorganisms. These products can be not only sugars, proteins, nucleic acids, or complex combinations of these things, but also living entities like cells or tissues.

Even older insulin derived from the pancreas of pigs is considered biologic therapy.

Generally, biologic therapy represents the latest advancements in biomedical research. Gene-based and cellular biologic therapy may be available for various medical conditions that don't have other treatment options.

This contrasts with traditional non-biologic pharmaceutical drugs, which are synthesized in a laboratory via chemical processes without using parts of living things.

The oldest forms of biologic therapy started with serum therapy or antitoxin therapy. Early biologic therapy was effective in treating diphtheria, tetanus, and rabies, but came with an unwanted side effect of serum sickness. Ground-breaking technologies developed in the 20th century led to multiple advances in this field, providing treatment for previously incurable or uncontrollable diseases.

What Types of Biologic Therapy Are Available?

Some of the general classes of biologics include:

  • Blood or other blood products (like platelets)
  • Allergenics
  • Somatic cells
  • Gene therapy (such as for genetic conditions)
  • Tissues (like tendons, ligaments, or other materials used for transplantation)
  • Recombinant therapeutic proteins (such as insulin, interferons, or erythropoietin)
  • Monoclonal antibodies (like those used to treat autoimmune diseases and cancer)
  • Vaccines (such as for disease prevention)
  • Antitoxins (such as to treat a snakebite)
  • Botox (onabotulinumtoxina)
  • Steroid hormone therapies (like estrogen, testosterone)
  • Recombinant nucleic acids (such as those developed for genetic hypercholesterolemia)
  • Stem cell therapies (such as for certain cancers or genetic diseases)
  • Other cell therapies (like specific T cells used to treat cancer)

How Does Biologic Therapy Work?

Different biologic therapies have different purposes, targets, and design, and they all work a little differently. Don’t hesitate to ask your healthcare provider if you have questions about the particular biologic therapy relevant to you.

As an example, monoclonal antibodies are lab-made antibodies specifically designed to target certain antigens. When attached to these foreign substances, the monoclonal antibodies can help the immune system destroy the cells containing the antigen. Monoclonal antibodies can target many diseases, including some kinds of cancer.

Monoclonal antibodies are made from mouse proteins, human proteins, or a combination of mouse and human proteins:

  • Murine monoclonal antibodies are derived from mouse proteins and their names will end in -omab.
  • Chimeric monoclonal antibodies are made from part mouse and part human. These names end in -ximab, like rituximab, a cancer drug also found to be effective in preventing multiple sclerosis relapses.
  • Humanized forms have small parts of mouse proteins attached to human proteins. You can recognize them by the suffix -zumab.
  • Human monoclonal antibodies are made purely from human proteins. The names of these products end in -umab.

If a biologic has “ab” at the end of its name, it is a good clue that the product is some kind of modified antibody.

How are Biologic Therapies Different from Traditional Pharmaceutical Drugs?

In general, the manufacturing process for biologics is more complicated than that for small molecule drugs (“non-biologic” drug treatments, such as aspirin). This is part of why biologics are typically more expensive than non-biologic treatment alternatives. Because the manufacturing process is so complicated, the structure of biologics may not be fully understood. It may be difficult or impossible for another company to exactly replicate it.

Biologics are larger, more complex molecules compared to traditional pharmaceutical drugs. Unlike traditional pharmaceuticals, they require some component from a living organism in order to be manufactured.

Microbial contamination is a bigger concern with biologics than non-biologic drugs. A sterile environment is needed throughout the manufacturing process for biologic drugs, whereas having germ-free conditions may be needed only for later manufacturing steps with traditional pharmaceutical drugs.

Biologics tend to be more sensitive to heat and light. Often, they cannot be taken by mouth, but must be given by injection or infusion.

Conditions That Can Be Treated With Biologic Therapy

More recently-developed biologic therapies have revolutionized the treatment of many different diseases. They have been especially important for the treatment of autoimmune diseases, cancer, and certain genetic conditions.

For example, biologic therapies have been developed to treat the following:

  • Rheumatoid arthritis
  • Psoriasis
  • Ankylosing spondylitis
  • Crohn's disease
  • Multiple sclerosis
  • Diabetic retinopathy
  • Age-related macular degeneration
  • Diabetes
  • Gastric cancer
  • Breast cancer
  • Colon cancer
  • Forms of leukemia and lymphoma
  • Infertility
  • Osteoporosis
  • Cystic fibrosis
  • Hemophilia
  • Sickle cell disease

Biologics in Autoimmune Diseases

Some of the most commonly used biologics are used for autoimmune diseases, diseases in which the body’s immune system plays a role in abnormally attacking its own tissue. Rheumatoid arthritis, psoriasis, type 1 diabetes, and Crohn’s disease are all examples of autoimmune diseases.

Many of these particular therapies are FDA-approved to treat more than one type of autoimmune disease. In some cases, healthcare providers may prescribe these treatments off-label if they haven’t undergone the full suite of studies needed for FDA-approval, but there is still good reason to think they might be effective.

Because biologics are often expensive and more difficult to administer, they are often (but not always) given after you have tried another non-biologic type of therapy.

One of the most common types of modern biologic therapies for autoimmune disease is the group of TNF inhibitors or blockers. TNF blockers include the popular drugs etanercept (Enbrel), adalimumab (Humira), and infliximab (Remicade). These drugs all block the downstream inflammatory effects of an immune molecule called TNF-alpha. They are FDA-approved for several different autoimmune diseases.

Other biologics have been developed to block the receptors for different immune molecules. Others were designed to target T cells, specific cells in the immune system. Some of these other biologics important in autoimmune disease include:

Another important biologic in autoimmune disease therapy is interferon beta-1a. Interferon beta-1a is marketed under several brand names including Avonex, Betaseron, Extavia, and Rebif. These and other biologics are used in the treatment of multiple sclerosis to reduce the number of relapses, delay progression of disability, and limit new disease activity.

Biologics in Cancer Treatment

Biologic therapies are also very important for cancer treatment, and many continue to be developed. There are many different types of these treatments. Sometimes they are used as a first-line treatment. Other times they are used after other treatments have failed, or in advanced cancers. Often, they are used in addition to other treatments.

Immunotherapy is a type of biologic therapy used in cancer treatment to help your immune system work to fight cancer. Several types of immunotherapy exist, including these examples:

  • Immune checkpoint inhibitors: These drugs block immune checkpoints. When these parts of the immune system's response are blocked, your body's immune cells can respond more strongly to cancer.
  • T-cell transfer therapy: With this form of treatment, immune cells taken from your tumor are treated in a lab before being put back into your body. The lab modifications boost the natural ability of these cells to fight cancer.
  • Monoclonal antibodies: These proteins are designed to bind to specific antigens, or targets, on cancer cells as a way of flagging these cells to the immune system.
  • Treatment vaccines: Unlike vaccines that help prevent disease, these vaccines boost your immune system's response to disease, in this case, cancer cells.
  • Immune system modulators: This treatment enhances the body's immune response against cancer.

Biologics in Rare Genetic Diseases

Biologic therapy is also very important in the treatment of rare genetic diseases. Gene therapy is a form of biologic therapy that modifies a person's genes to treat or cure diseases.

Gene therapy work in different ways. Some forms replace a disease-causing gene with a healthy copy of that gene. Others turn off a disease-causing gene or introduce a new or modified gene.

Huntington's disease is a genetic disease that affects the nervous system, causing behavioral changes and involuntary movements. There is no cure for Huntington's disease, but gene therapy is showing promise in clinical trials.

One form of gene therapy reduces how much Huntington protein is produced to slow or stop progression of the disease. Another form boosts the brain and body's ability to ward off the progression of the disease naturally.

Other biologic therapies are also used to treat various rare diseases:

  • Enzyme replacement therapy for Gaucher disease
  • Blood clotting factors for hemophilia
  • Immunoglobulins for people with certain genetic immune disorders
  • Stem cell transplants used to treat many types of rare genetic diseases, including sickle cell disease

Researchers are also continuing to develop RNA therapies and gene therapies that might ultimately be used to cure many rare diseases.

Potential Side Effects of Biologic Therapy

Potential side effects of biologics vary based on the specific biologic therapy involved. In some cases, these side effects are quite mild, such as a rash. In other cases, they can be fatal.

Side effects can occur during or after treatment. Common ones may include:

  • Pain, swelling, soreness at the needle site
  • Redness, itching, rash at the needle site
  • Fever
  • Chills
  • Weakness
  • Dizziness
  • Nausea or vomiting
  • Muscle or joint aches
  • Fatigue
  • Headache
  • Trouble breathing
  • Low or high blood pressure
  • Swelling and weight gain from retaining fluid
  • Heart palpitations
  • Sinus congestion
  • Diarrhea
  • Infection
  • Organ inflammation

Many of these treatments come with a risk of immunosuppression. That means that part of your immune system can’t respond to fight off infections the way it normally would. This might make you more susceptible to certain types of infections. In some cases, the risk is reactivating dormant infections that otherwise wouldn’t necessarily give you a problem, such as tuberculosis.

Certain biologic therapies that target the immune system may also increase the risk of certain cancers. However, this is not true of all biological therapies. Also, the risk might be only small or nonexistent in a drug that otherwise gives many potential benefits.

Rare reactions to biologic therapy like immunotherapy include severe or fatal allergic reactions and inflammation-related reactions.

Talk things through with your health provider to make sure you make a decision that makes sense for you. Risks are generally better understood for biologic therapies that have been around for a while compared to newer treatments. Your healthcare provider can give you a better idea of the potential side effects of a particular biologic therapy in your situation.

Are Biologics Safe to Use During Pregnancy and Breastfeeding?

Most biologic therapies have not been studied in pregnant or breastfeeding women, but we know that specific biologic treatments may be dangerous for a fetus or a breastfeeding infant. However, it may also be a risk to stop a biologic treatment if you are already using one.

Talk to your healthcare provider about your particular situation and the overall risks and benefits. If you are taking a biologic therapy and find out that you are pregnant, don’t stop taking it right away. Instead, call your practitioner’s office and tell them the situation.

Risks of Biologic Therapy

As always, your healthcare provider will want to do a thorough medical history and clinical exam before prescribing a biologic therapy. This will help your practitioner make sure that the potential benefits of treatment outweigh potential risks.

In some cases, your healthcare provider will need to make sure you don’t have certain risk factors before starting a biologic. People with certain medical conditions might not be able to get biologic treatments.

You might need to get a screening test for tuberculosis or a screening test for hepatitis. But this won’t be necessary for every type of biologic therapy. Your healthcare provider will let you know what screening tests might make sense for you.

Generally speaking, you shouldn’t be given certain types of vaccines (those which contain any live viral components) while taking biologic drugs that affect your immune system and can make you more likely to get infections. So you may need to get some of these vaccines before starting therapy.

Can Biologics Be Taken With Other Non-Biologic Therapies?

Biologic treatments are often taken alongside older non-biologic therapies. For example, someone with rheumatoid arthritis might still continue taking methotrexate while adding an additional biologic treatment.

However, it will also depend on your specific situation. In some cases, the biologic treatment will take the place of previous non-biologic therapies.

How Are Biologics Administered?

This varies based on the specific biologic product. Currently, most biologics cannot be taken by mouth, though pharmaceutical companies are working to develop oral therapies.

In general, biologics are given as injections or as infusions. You might be able to give yourself an injection under the skin, or you might want the help of a family member.

Biologic therapies are sensitive to heat and light, so carefully follow any preparation instructions given by your clinician.

Intravenous infusions are administered through a vein. These usually take longer, perhaps a couple of hours. These are typically given in a medical office.

In some cases, only a single treatment is needed. In others, the biologic treatment will need to be taken at regular intervals over time.

How Quickly Do Biologics Work?

How quickly a biologic drug works depends on the particular therapy. For example, a shot of insulin begins to work almost immediately. However, for something like a biological therapy for rheumatoid arthritis or psoriasis, you might not notice improvements for a couple of weeks or even a month or more.

Ask your healthcare provider what you might expect in your particular situation. If your treatment takes more than one session, your provider will want to see you often for physical exams and medical tests, including blood tests.

What Are Biosimilars?

Basically, biosimilars are to biologics as generic drugs are to brand-name drugs. Biosimilars may offer cheaper and more affordable options to patients. However, unlike generic drugs, biosimilars can't be copied exactly.

This has to do with the way biologic products are manufactured. Biologic products are more complex and may not even be the same from dose to dose or batch to batch. It is difficult for competing companies to produce products that are exactly equivalent to the biologic therapies first developed.

Like the original, or reference, biologic drug, biosimilar drugs:

  • Are made with the same types of living sources
  • Are given to the patient in the same way
  • Have the same strength, dosage, potential treatment benefits, and potential side effects

If a biosimilar is available, make sure to talk to your healthcare provider about whether it is the best option for you. It also makes sense to make sure that the FDA has designated the biosimilar as interchangeable with the original product.


Biologic therapy includes any therapy made from a living source. Some forms like insulin and antitoxin therapy have been around for a long time. More recent advancements in biotechnology have allowed for rapid progress in the development of more and more types of biologic therapy.

Biologic products can help treat a wide range of conditions including skin diseases, chronic bowel diseases, diabetes, and arthritis. Immunotherapy, a type of biologic therapy, is used to treat some cancers, and gene therapy can treat and possibly cure genetic diseases.

Biosimilars are similar to the original biologic product, but may be available at more affordable prices. Talk to your healthcare provider about your biologic therapy options. Discuss possible side effects and the potential benefits of therapy. Biologics can prevent or slow disease progression and may even offer a cure.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
Ruth Hickman

By Ruth Jessen Hickman, MD
Dr. Hickman is a freelance medical and health writer specializing in physician news and patient education.