What Does It Mean When a Drug Ends in mAb? Decoding Monoclonal Antibodies

October 9, 2025 •

5 min read

According to the U.S. Pharmacopeia, monoclonal antibodies (mAbs) are lab-made proteins designed to mimic the immune system's natural defenses, and they are used to treat a wide array of conditions, from cancer to autoimmune disorders. When a drug name ends in –mab, it signals that it belongs to this class of highly specific, targeted biological agents.

Quick Summary

A drug name ending in -mab denotes a monoclonal antibody, a laboratory-produced protein engineered to target specific antigens on diseased cells. These targeted biologic therapies are used for treating various conditions, including cancer, autoimmune disorders, and infections, by harnessing the body's immune system.

Key Points

Signifies a Monoclonal Antibody (mAb): The suffix -mab identifies a drug as a monoclonal antibody, a laboratory-produced protein that targets a specific substance in the body.
Functions as a Targeted Biologic: Monoclonal antibodies are a form of biologic drug that mimic the body's natural antibodies to attack specific antigens found on diseased cells, like cancer or pathogens.
Infixes Indicate Source and Target: The letters preceding -mab can reveal the drug's origin (e.g., -u- for human, -xi- for chimeric) and its target (e.g., -tu- for tumor).
Variety of Therapeutic Actions: mAbs can work in different ways, including blocking growth signals, carrying toxic payloads directly to a target, or tagging cells for immune system destruction.
Used for Diverse Conditions: mAb therapy is employed for treating a wide range of diseases, including cancer, autoimmune disorders, infectious diseases, and neurological conditions.
Offers Precise Treatment with Specific Risks: While more targeted and often associated with fewer side effects than chemotherapy, mAbs can cause infusion reactions and other immune-related adverse events.

What is a Monoclonal Antibody (mAb)?

At its core, a monoclonal antibody, or mAb, is a laboratory-engineered protein designed to act like the natural antibodies produced by our immune system. In the body, antibodies circulate in the bloodstream, identifying and neutralizing foreign substances, or antigens, such as viruses, bacteria, or cancer cells. A monoclonal antibody mimics this process by being designed to target a single, specific antigen with pinpoint accuracy. The suffix –mab in a drug's generic name is the key indicator that it is a monoclonal antibody.

Since the first FDA approval in 1986, the field of mAb therapy has grown dramatically, with over 100 approved agents treating a wide range of diseases. This success stems from their ability to offer a targeted approach to medicine, minimizing damage to healthy cells that is often associated with traditional therapies like chemotherapy.

Decoding the Name: What the Prefix and Infixes Tell You

The full name of an mAb drug can tell you a lot about its properties, following a naming convention established by international bodies like the World Health Organization (WHO) and the United States Adopted Names (USAN) Council. While the -mab suffix identifies the drug as a monoclonal antibody, the letters before it provide additional information about the drug's target and source.

Origin or Source Infixes

-o-: Derived from a mouse (murine) source, e.g., Muromonab.
-xi-: Chimeric, meaning a combination of human and mouse proteins, e.g., Rituximab.
-zu-: Humanized, with most of the antibody structure being human, e.g., Bevacizumab.
-u-: Fully human, with a completely human protein sequence, e.g., Adalimumab.

Target Infixes

-tu-: Targets a tumor.
-li-: Targets the immune system.
-ci-: Targets the circulatory system.
-vir-: Targets a virus.

By combining these parts, you can begin to decode the drug's function. For example, the name Bevacizumab can be broken down as: Bevac (distinctive prefix) + -ci- (circulatory system) + -zu- (humanized) + -mab (monoclonal antibody).

How Do Monoclonal Antibodies Work?

The therapeutic action of mAbs is diverse, depending on how they are designed. They can be categorized into three main types based on their function:

Naked Monoclonal Antibodies: These are the most common type and work on their own, with no additional drugs or radioactive material attached. They can act by:
- Tagging cancer cells, making them more visible for the immune system to destroy.
- Blocking protein-cell interactions necessary for cancer cell growth.
- Blocking immune checkpoint proteins that tumors use to hide from the immune system.
Conjugated Monoclonal Antibodies: Also known as tagged or loaded antibodies, these are linked to a chemotherapy drug or a radioactive particle. The mAb acts as a homing device, delivering the toxic payload directly to the target cells, which minimizes harm to healthy tissue. Examples include ado-trastuzumab emtansine (Kadcyla), which delivers a chemo drug, and ibritumomab tiuxetan (Zevalin), which delivers a radioactive substance.
Bispecific Monoclonal Antibodies: This newer class of mAbs is made of two different antibodies, allowing it to bind to two different proteins at once. For example, one part might attach to a cancer cell, and the other to an immune T-cell, bringing them together to trigger an immune attack on the cancer.

Common Uses and Applications of mAbs

Monoclonal antibodies are used to treat a wide array of conditions, including:

Cancer: Treatment for many cancers, including breast cancer (Trastuzumab), non-Hodgkin's lymphoma (Rituximab), and melanoma (Pembrolizumab).
Autoimmune Disorders: Conditions like rheumatoid arthritis (Adalimumab), Crohn's disease (Infliximab), and lupus (Belimumab).
Infections: Used to treat certain viral infections, including Ebola (Ansuvimab) and, during the pandemic, COVID-19 (Bebtelovimab).
Neurological Disorders: For example, multiple sclerosis (Ocrelizumab) and Alzheimer's disease (Lecanemab).
Cardiovascular Disease: Used to lower cholesterol levels (Alirocumab) and address certain heart conditions.

Benefits and Risks of Monoclonal Antibodies

Like all medications, mAbs offer significant benefits but are also associated with risks. Their highly targeted nature is a double-edged sword that provides both a key advantage and a specific set of potential side effects.

Comparison of mAb Benefits vs. Risks


Feature	Benefits of mAb Therapy	Risks and Considerations
Targeting	High specificity means targeting only diseased cells, minimizing harm to healthy tissues and reducing off-target side effects.	High specificity can cause side effects related to the targeted pathway, even if the target is found on some healthy cells.
Immune Response	Activates or enhances the body's own immune system to fight disease, offering a potentially powerful and long-lasting effect.	Can cause infusion reactions (allergic response), cytokine release syndrome, or reactivation of latent infections due to immunomodulation.
Side Effects	Generally better safety profile than conventional chemotherapy, with side effects often less severe.	Can cause serious, though rare, side effects like heart problems, lung inflammation, or severe skin rashes.
Origin	Using humanized or fully human mAbs minimizes the risk of the patient's immune system attacking the drug itself, improving tolerance.	Older mouse-derived mAbs (`-omab`) and chimeric mAbs (`-ximab`) carry a higher risk of immune rejection and severe reactions.
Mechanism	Versatile mechanisms, including direct cell killing, growth signal blocking, or delivering targeted payloads to maximize therapeutic effect.	Some mechanisms, like blocking VEGF to inhibit tumor blood vessels, can lead to side effects like high blood pressure or poor wound healing.

The Future of mAb Therapy

The field of monoclonal antibody research is evolving rapidly, with exciting new developments on the horizon. Advancements are focusing on improving efficacy, safety, and accessibility.

Advanced Engineering: Next-generation technologies are creating more sophisticated mAbs, such as bispecific antibodies that engage two targets at once.
Targeted Delivery: Better antibody-drug conjugates (ADCs) are being developed, as well as gene therapy-mediated delivery, which could provide long-term antibody expression from a single treatment.
Accessibility: The development of biosimilars—near-identical copies of existing mAbs—is increasing competition and expected to lower the cost and increase access to these life-saving treatments.
Combination Therapies: Researchers are exploring combining mAbs with other immunotherapies, such as CAR-T cell therapy, to enhance anti-tumor responses and maximize therapeutic benefit.

Conclusion

When a drug ends in –mab, it is a biological agent designed to perform a highly specific, targeted function within the body, much like the immune system's own antibodies. The letters preceding the suffix can provide clues about the drug's origin and what it targets. These monoclonal antibodies have revolutionized medicine by offering precise and potent treatments for a growing list of complex diseases, including cancer, autoimmune disorders, and infections. While they offer significant benefits over traditional therapies, they also carry distinct risks that must be managed by healthcare professionals. As research continues, the use of mAbs, enhanced by advanced engineering and combination strategies, is poised to become an even more integral part of modern medicine. For additional information on how these drugs target cancer, the American Cancer Society offers a detailed guide to monoclonal antibody treatments.

American Cancer Society: Monoclonal Antibodies and Their Side Effects

Frequently Asked Questions

A conventional drug is typically a small, chemically synthesized molecule that can affect multiple cell types. A monoclonal antibody, in contrast, is a large, biologically produced protein designed to recognize and bind to only one specific target (antigen), making it highly precise.

Not exclusively. While many mAbs are used in cancer treatment, they also treat a wide range of other diseases, including autoimmune disorders like rheumatoid arthritis, infections like COVID-19, and neurological diseases.

The high specificity of monoclonal antibodies is what minimizes damage to healthy cells. By being designed to target a specific antigen unique to diseased cells, the mAb leaves most healthy cells unharmed. In conjugated mAbs, this precision allows a toxic payload to be delivered directly to the target.

These letters indicate the source of the antibody. The infix -u- means the antibody is fully human, while -xi- signifies it is chimeric (a mix of human and mouse proteins). The source impacts the risk of immunogenicity, or the body's immune reaction to the drug, with fully human antibodies having the lowest risk.

The most common side effects include infusion-related reactions, which can cause fever, chills, nausea, vomiting, or skin rashes. These are often more pronounced with the first few doses. More serious side effects can occur but are less common.

Yes, mAbs can be used to treat or prevent infectious diseases. During the COVID-19 pandemic, certain mAbs were granted Emergency Use Authorization to bind to the SARS-CoV-2 virus, preventing it from entering healthy cells.

Monoclonal antibody therapy is most often administered via intravenous (IV) infusion or subcutaneous injection. The method and frequency depend on the specific drug and condition being treated.