Nomenclature of monoclonal antibodies

The nomenclature of monoclonal antibodies is a naming scheme for assigning generic, or nonproprietary, names to a group of medicines called monoclonal antibodies. This scheme is used for both the World Health Organization’s International Nonproprietary Names and the United States Adopted Names. In general, suffixes are used to identify a class of medicines; all monoclonal antibody pharmaceuticals end with the suffix -mab. However, different infixes are used depending on the structure and function of the medicine.

Infix for origin/source
The infix preceding the -mab suffix denotes the animal origin of the antibodies. Although the original monoclonal antibodies were produced in mice (infix, -o-), these antibodies are recognized as foreign by human immune systems and may be rapidly cleared, provoke an allergic reaction, or both. Therefore, parts of the antibody may be replaced with human sequences. If the constant region is replaced with the human form, it is termed chimeric and the infix used is -xi-. Part of the variable regions may also be substituted, in which case it is termed humanized and the infix used is -zu-. Antibodies originating in humans use -u-.

Infix for target
The infix preceding the source of the antibodies refers to medicine’s target. Most of these consist of a consonant, vowel, then another consonant. For ease of pronunciation and to avoid awkwardness, the final consonant is dropped if the following infix begins with a consonant (such as -zu- or -xi-). Examples of these include -ci(r)- for the circulatory system and -tu(m)- for miscellaneous tumors (cancers).

Prefix and second word
Finally, the prefix carries no special meaning and should be unique for each medicine. A second word may be added if there is another substance attached or linked.

Examples
Abciximab is a commonly used medication to prevent platelets from clumping together. It can be broken down into ab- + -ci(r)- + -xi- + -mab. Therefore, it is a chimeric monoclonal antibody used on the cardiovascular system.

Another example is the breast cancer medication trastuzumab, which can be broken down into tras- + -tu(m)- + -zu- + -mab. Therefore, it is a humanized monoclonal antibody used against a tumor.