Incorporation of Unnatural Amino Acid into Antibody Fragment for Creating a Stable Antibody Drug Conjugate

The traditional chemotherapy drug has been used as a standard cancer treatment, however it has resulted a modest survival benefit and damaged non-cancerous cells. Thus, the novel strategies which can improve selectivity and specificity in chemotherapy are urgently needed. Antibody drug conjugate (ADC) combines monoclonal antibody and cytotoxic drug is a potential regimen as targeted therapy. However, the heterogeneous mixtures has been observed using the current ADC methods. Here, we develop the strategy for generation a stable ADC utilising modified single chain antibody fragment (scFv) containing azide group for click chemistry reaction with alkyne containing cytotoxic drug. This research focused on targeting prostate cancer as a model disease utilising targeting prostate specific membrane antigen (PSMA) receptor which is overexpressed in all prostate cancer stages. The unnatural amino acid para-azido phenyl alanine (pAzF) has been successfully incorporated into anti-PSMA J591 scFv and specifically bound and internalised into PSMA positive cancer cells. This mutant scFv were also successfully conjugated into a linker containing cyclo-alkyne, DBCO-PEG4-DBCO as a model for creating ADC through copper-free click chemistry reaction. This bioconjugation method is promising as a versatile strategy for generating a stable ADC to improve therapeutic efficacy in cancer treatment.