For monoclonal antibodies, a decision has been taken to discontinue the usage of the well-known stem "-mab" and a novel International Nonproprietary Names (INN) monoclonal antibody nomenclature scheme has been developed, according to the findings of a study published in "The Lancet". For clinical usage, monoclonal antibodies are the largest class of biological products. These monoclonal antibodies consist of a variety of distinct structures, from small fragments to unmodified, intact, or modified immunoglobulins, all of which contain an antigen binding domain.

For clinical development, pharmacovigilance, prescribing, licensing and identification of counterfeits, suitable nomenclature for all pharmaceutical substances is crucial. Such nomenclature is particularly suitable for monoclonal antibodies, and the World Health Organization INN programme implemented a monoclonal antibodies nomenclature scheme in 1991, utilizing the stem "-mab" for identifying this group.

Recently, the INN programme reported a rise in INN requests for monoclonal antibodies, that is making the choice of distinguishable INNs extremely hard. This fashion is not likely to alter in the foreseeable future. With the ongoing advances in technology, several engineered and modified monoclonal antibodies are being submitted. Notably, there are 880 INNs with the stem "-mab". For easing this situation, the World Health Organization INN expert group thus agreed to revise the system.

At the 73rd INN Consultation held in October 2021, the revised system received acceptance and adoption by World Health Organization. A radical decision was taken to discontinue the usage of well-known stem -mab (unpublished). The novel INN monoclonal antibody nomenclature scheme was created for equally dividing substances containing an immunoglobulin variable domain into 4 groups: (i) 1 for bispecific and multispecific immunoglobulins, and (ii) 3 groups for monospecific immunoglobulins.

The stem -mab was replaced by 4 novel stems covering all previous usage of -mab. For facilitating the coining of the novel INN, the novel stems are different from each other.

For monospecific, full-length immunoglobulins with engineered constant domains, the term "-bart" is utilized.

For monospecific, full-length, and Fc unmodified immunoglobulins, the novel stem "-tug" is utilized.

For monospecific fragments of any kind that are derived from an immunoglobulin variable domain, the stem "-ment" is now utilized.

For bispecific or multispecific immunoglobulins (irrespective of their shape, type, format), the stem "-mig" is utilized.

Majority of the target-related infixes utilized in the novel scheme are unaltered. But, some infixes are revised. It is anticipated that the novel scheme will permit pharmacologically meaningful distinctions and choice of distinguishable and pronounceable INNs. This scheme will stay in usage for a significant period of time. But, a few small alterations may be essential in the future for accommodating alterations in monoclonal antibody development and clinical usage.