Method for the selective and quantitative functionalization of immunoglobulin Fab fragments, conjugate compounds obtained with the same and compositions thereof

Abstract

The invention provides chemical conjugates between an immunoglobulin Fab fragment and molecular entities imparting diagnostic or therapeutic utility, whereby the only sites of conjugation on the Fab fragment are one or both of the sulfhydryl groups deriving from the selective and quantitative reduction of the inter-chain disulfide bond of said Fab fragment and whereby said molecular entities imparting diagnostic or therapeutic utility have at least one free sulfhydryl-reactive group, characterized in that the conjugation stoichiometric molar ratio molecular entity to Fab fragment is in the range from 0.95 to 1.05 or in the range from 1.95 to 2.05. The invention also provides a process for preparing said conjugates and pharmaceutical compositions thereof.

Description

field of invention [0001] The present invention relates to conjugates of Fab fragments (Fab) of immunoglobulins, wherein said Fab is quantitatively and selectively functionalized only at predetermined specific desired sites on the molecule. [0002] The invention also relates to methods for achieving said selective and quantitative functionalization, as well as pharmaceutical compositions comprising said conjugates. Background of the invention [0003] Monoclonal antibodies (mAbs) are proteins with the well-known ability to localize, in vitro and in vivo, to cells or tissues exposing the antigen to which they are specific. This property is maintained in some of their well-known proteolytic fragments, such as Fab, Fab' and F(ab') 2 . In particular, immunoglobulin Fab fragments (hereinafter also plural, referred to simply as Fab) maintain this property. [0004] It is well known that different types of diagnostic or therapeutic molecules or precursors thereof can be covalen...

AI Technical Summary

Problems solved by technology

[0021] In the case of Fab fragments, which bear the antigen-binding site, researchers are strongly aware of the problem of selective conjugation only at the C-terminal sulfhydryl group, which cannot be achieved by methods used for intact immunoglobulins. solve

Despite this apparent need, no other species that can specifically and quantitatively direct the conjugation reaction to only those thiol groups that do not participate in stable polypeptide chain folding, i.e., two thiol groups derived from interchain disulfide bonds, has not been described so far. method

Images