Antibody-drug Conjugates (ADCs) are expected to be the next generation of antibody therapeutics. Current unmodified monoclonal antibodies (MAbs) do not cure, and can only extend survival by 5-6 months. In addition, many antibodies suffer from drug resistance due to mutations in cell-signalling pathways. The main method for conjugating drugs to MAbs has been via the thiol side-chains of cysteine residues (Cys-SH). Though affording a certain degree of stoichiometric control during conjugation, this protocol yields only low drug-loading ratios, due mainly to the large Mab-drug conjugate becoming notoriously insoluble at higher drug loadings.
With its proprietary OptiLink technology platform, PhotoBiotics has adopted an altogether more novel approach using much smaller antibody fragments (scFvs) that are relatively easy to bioengineer with lysine residues for multiple drug-molecule conjugation to their -NH2 side-chains. Quite counter-intuitively, this approach provides far higher drug loadings than have so far been achieved with whole MAbs, without running the risk of drug-scFv-conjugate insolubility. This provides:
- Applications in both therapy and diagnostic imaging
- ‘See & Treat’ as a time-saving and therapeutically enhancing opportunity
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