What Drugs Are Considered Monoclonal Antibodies? A Comprehensive Guide

October 9, 2025 •

4 min read

In 2024, biologics, including a high number of monoclonal antibodies, represented 32% of all new drugs approved by the FDA [1.7.1]. So, what drugs are considered monoclonal antibodies, and how do these advanced therapies work to combat complex diseases?

Quick Summary

Monoclonal antibodies are lab-created proteins that mimic natural antibodies. They treat diseases like cancer and autoimmune disorders by targeting specific cells or proteins in the body to help the immune system fight more effectively [1.2.1].

Key Points

Definition: Monoclonal antibodies (mAbs) are lab-made proteins that mimic natural antibodies to target specific cells or proteins causing disease [1.2.3].
Mechanism: They work by marking cancer cells for destruction, blocking cell growth signals, or delivering treatments like chemotherapy directly to tumors [1.3.5].
Types: mAbs are categorized as murine (-omab), chimeric (-ximab), humanized (-zumab), and human (-umab), with decreasing levels of immunogenicity [1.2.2].
Common Uses: They treat cancers (e.g., Rituximab, Trastuzumab) and autoimmune disorders (e.g., Adalimumab, Infliximab) [1.2.3].
Side Effects: Common side effects include flu-like symptoms and rashes, while more serious risks involve infusion reactions and an increased chance of infection [1.6.5].
Naming: Most monoclonal antibody drug names end with the suffix '-mab' [1.3.2].
Administration: Most are administered via intravenous (IV) infusion, though some are given as subcutaneous injections [1.3.2].
Innovation: Newer types, like antibody-drug conjugates (ADCs) and bispecific antibodies, offer even more precise and powerful treatment mechanisms [1.2.2].

Understanding Monoclonal Antibodies (mAbs)

Monoclonal antibodies, often abbreviated as mAbs or Moabs, are a significant class of medications used to treat a wide array of conditions, including various cancers, autoimmune disorders, and infections [1.2.1, 1.2.2]. These are not traditional chemical drugs but are lab-made proteins designed to function like the natural antibodies produced by the human immune system [1.2.3]. The key to their effectiveness lies in their specificity. Each monoclonal antibody is engineered to recognize and bind to a single, specific target, known as an antigen [1.2.5]. These antigens can be proteins on the surface of cancer cells, viruses, or substances that cause inflammation [1.2.1].

First developed by Georges Kohler and Cesar Milstein in 1975, this technology has revolutionized medicine [1.4.4]. The first mAb approved for human use was muromonab-CD3 in 1986, used to prevent kidney transplant rejection [1.2.3, 1.3.2]. Since then, the number of approved mAb therapies has steadily increased, becoming a cornerstone of modern pharmacology [1.3.2]. Their names often end with the suffix "-mab," signaling their classification [1.3.2].

How Do Monoclonal Antibodies Work?

The mechanism of action for monoclonal antibodies is diverse and tailored to their specific target. They can function in several ways [1.2.3, 1.3.5]:

Marking Cancer Cells: Some mAbs act like a flag. They attach to cancer cells, making them more visible to the body's immune system, which can then identify and destroy them. Rituximab is an example that binds to the CD20 protein on certain cancer cells [1.2.4].
Blocking Cell Growth: Many cancer cells rely on specific proteins to grow and spread. Monoclonal antibodies can block these proteins, effectively halting the cancer's progression. Trastuzumab (Herceptin), for instance, targets the HER2 protein in some breast and stomach cancers [1.2.2, 1.2.3].
Delivering Treatment: Some mAbs are 'conjugated,' meaning they are attached to a chemotherapy drug or a radioactive particle. These antibodies act as a homing device, delivering the toxic substance directly to cancer cells while minimizing damage to healthy cells. This is known as an Antibody-Drug Conjugate (ADC) [1.2.2, 1.3.3]. Ado-trastuzumab emtansine (Kadcyla) is an example of an ADC [1.2.2].
Immune System Modulation: Certain mAbs, known as checkpoint inhibitors, work by removing the 'brakes' on the immune system. Cancer cells can sometimes produce signals that suppress the immune response. Checkpoint inhibitors block these signals, allowing immune cells (like T-cells) to attack the cancer more effectively [1.3.5]. Pembrolizumab (Keytruda) is a well-known checkpoint inhibitor [1.2.3].
Bispecific Antibodies: These are advanced drugs made from parts of two different mAbs, allowing them to attach to two different proteins simultaneously. For example, one part might bind to a cancer cell while the other binds to an immune cell, bringing them together to initiate an attack [1.2.2].

Types of Monoclonal Antibodies

Monoclonal antibodies are classified based on their protein source, which affects their potential to cause an immune reaction in humans. The naming convention often reflects their origin [1.2.2, 1.4.4].


Type	Suffix	Composition	Immunogenicity (Risk of Immune Reaction)
Murine	-omab	100% Mouse proteins	High
Chimeric	-ximab	~65% Human, with mouse variable regions	Medium
Humanized	-zumab	~95% Human, with small parts of mouse proteins	Low
Human	-umab	100% Human proteins	Very Low

Initially, all mAbs were made from mouse proteins (murine), but these often triggered a significant immune response in patients [1.4.4]. To reduce this, scientists developed chimeric and then humanized versions, progressively replacing mouse components with human ones [1.4.2]. Today, many new mAb drugs are fully human, produced using technologies like transgenic mice or phage display, making them safer and more effective [1.4.4].

Common Examples and Their Uses

Monoclonal antibodies are used for a diverse range of diseases [1.2.3]:

Oncology (Cancer):
- Rituximab (Rituxan): Treats non-Hodgkin's lymphoma and chronic lymphocytic leukemia by targeting the CD20 protein on B-cells [1.2.3, 1.11.3].
- Trastuzumab (Herceptin): Used for HER2-positive breast and stomach cancers [1.2.3, 1.5.5].
- Bevacizumab (Avastin): An anti-angiogenesis therapy that stops tumors from forming new blood vessels, used for various cancers [1.2.2].
- Pembrolizumab (Keytruda): An immunotherapy used for melanoma, lung cancer, and many other cancer types [1.2.3].
Autoimmune Diseases:
- Adalimumab (Humira): Treats rheumatoid arthritis, Crohn's disease, plaque psoriasis, and ulcerative colitis by blocking Tumor Necrosis Factor-alpha (TNF-α), a substance that causes inflammation [1.9.1, 1.9.4].
- Infliximab (Remicade): Also a TNF-α inhibitor used for similar conditions as adalimumab [1.2.3].
- Ustekinumab (Stelara): Treats psoriasis, psoriatic arthritis, and Crohn's disease [1.5.2].
Other Conditions:
- Omalizumab (Xolair): Used for severe allergic asthma and chronic hives [1.2.3].
- Denosumab (Prolia, Xgeva): Treats osteoporosis and prevents bone problems in cancer patients [1.5.2].
- Dupilumab (Dupixent): Treats eczema (atopic dermatitis), asthma, and nasal polyps [1.2.1].
- Evolocumab (Repatha): Used to manage high cholesterol.

Potential Side Effects and Risks

While more targeted than traditional chemotherapy, monoclonal antibodies are not without side effects. The side effects depend on the specific drug and what it targets [1.2.2].

Common side effects can include [1.6.5]:

Flu-like symptoms (fever, chills, fatigue, muscle aches)
Skin rashes or itching
Nausea and diarrhea
Low blood pressure

More serious, though less common, risks can involve [1.6.1, 1.6.5]:

Infusion reactions: Allergic-type reactions can occur during or shortly after the drug is administered intravenously. Symptoms can range from hives to severe issues like shortness of breath [1.6.1].
Increased risk of infections: Because mAbs modulate the immune system, they can sometimes lower the body's ability to fight infections [1.11.3].
Heart problems: Some mAbs, like trastuzumab, can increase the risk of congestive heart failure [1.10.3].
Organ-specific issues: Depending on the target, some drugs can cause problems with the lungs, liver, or kidneys [1.2.2, 1.10.3].

Conclusion

Monoclonal antibodies represent a powerful and precise tool in modern medicine. From fighting cancer to controlling chronic inflammation, these lab-engineered proteins have transformed the treatment landscape for many difficult diseases. As research continues, new mAbs are constantly being developed, offering more targeted and effective options for patients. The ongoing approvals by regulatory bodies like the FDA highlight their growing importance in pharmacology, with many new agents targeting novel pathways and providing hope for previously hard-to-treat conditions [1.7.1].

For more information, consult authoritative sources such as the National Cancer Institute. [1.2.4]

Frequently Asked Questions

The suffix '-mab' is a standard convention used to identify a drug as a monoclonal antibody, which is a type of biologic medication made from a single clone of an immune cell [1.3.2].

It depends on their mechanism. Some mAbs are a form of targeted therapy because they block specific functions in cancer cells. Others are considered immunotherapy because they help the body's own immune system attack the cancer. Some drugs can be both [1.2.2].

The first monoclonal antibody approved for use in humans was Orthoclone OKT3 (muromonab-CD3) in 1986. It was used to prevent kidney transplant rejection [1.2.3].

They are typically produced using hybridoma technology, where antibody-producing B-cells from an immunized animal (like a mouse) are fused with immortal myeloma cells. This creates a hybridoma cell line that can be cultured to produce large quantities of a specific antibody [1.8.3, 1.8.4].

Humanized antibodies (-zumab) are mostly human protein but contain small, critical parts from a mouse antibody. Fully human antibodies (-umab) are made entirely from human proteins, typically using transgenic mice or phage display technology, which further reduces the risk of an immune reaction [1.2.2, 1.4.4].

Yes, they are widely used to treat autoimmune diseases like rheumatoid arthritis and Crohn's disease, as well as conditions like severe asthma, high cholesterol, osteoporosis, and even migraine headaches [1.2.3].

Common side effects are often mild and can include flu-like symptoms such as fever, chills, and fatigue, as well as skin rashes, nausea, and diarrhea [1.6.5]. Infusion-related reactions are also possible [1.6.1].