Guidance on the establishment of new INN stems - 20070611

Guidance for INN applicants with regard to the establishment of new INN stems

5 November 2007

| Publication

The present system needs some modification. It needs some revision &

improvement to deal with specific problems. However, it has been used successfully

for 20 years and so changes should be carefully considered and implemented only

where they are necessary.

The stem -mab should be retained. Also -mab is to continue to be used for mAb

fragments. The description should clearly indicate if the product is a fragment.

The system for conjugates & radiolabelled mAbs need not be changed.

The stem -mab is to be used for all products containing an immunoglobulin variable domain which binds to a defined target.

The prefix peg- can be used for pegylated mAbs, but this should be avoided if it

leads to over-long INN. In most cases, it is best to adopt two-word INN for pegylated

mAbs, with the first word describing the mAb and the second being pegol. This is

consistent with INN for other pegylated substances.

The use of sub-stems is valuable, but possibly too complicated. The 'source' substem

should be kept, but redefined as 'the species on which the immunoglobulin

sequence of the mAb is based’. The 'tumour group' sub-stem should be simplified to

-tu(m)-, the other tumour sub-stems should be discontinued. But -tu(m)- should be

truncated to -t- or -tu-. Similarly -li(m)- should be truncated to -m- or discontinued &

replaced with more precise sub-stems, which relate to the target. Also the other substems

for 'disease or target' should be shortened, e.g. -fung- to -f- etc.

The use of Greek terminal letters to indicate e.g. differences in glycosylation cannot

be introduced retrospectively. However, mAbs which have the same amino acid

sequence but different glycosylation may need distinct INN, unless significant

differences on post-translational modifications are excluded /disproven. Particularly,

if the glycosylation has been glycoengineered to produce a different structure, then

the glycoengineered mAb should be given a different INN to the parent mAb.

When the antibody is directed against a toxin, the infix -toxa- can be used in the

name. For monoclonals conjugated to a toxin, the suffix -tox can be used in the

second word. This will be clarified in the mAB naming rules.

WHO Team

Access to Medicines and Health Products (MHP), Health Product Policy and Standards (HPS), INN and Classification of Medical Products (INN)

Editors

International Nonproprietary Name (INN) Programme

Number of pages

Reference numbers

WHO Reference Number: INN Working Document 07.2015