SBIR Phase I: Development of a Platform for Rapid "Plug and Play" Chemo-enzymatic Conjugation of Bio-therapeutics

This Small Business Innovation Research (SBIR) Phase I project proposes to develop a platform technology utilizing directed evolution to engineer transpeptidases (TPases) that will recognize sequences within native antibodies, and conjugate any small molecule, peptide or protein moiety of interest through a peptide bond. Current approaches for production of Antibody Drug Conjugates (ADCs) either produce mixtures that are hard to manufacture and characterize, or use technology for site-specific conjugation that necessitates remaking the antibody of interest after inserting potentially immunogenic peptide tags or non-natural amino-acids. In pre-clinical research, this approach will allow "plug and play" conjugation of several different antibodies with cytotoxin(s) of interest, allowing rapid identification of the best combination(s). Furthermore, in a manufacturing setting, these variant TPases will allow rapid production of ADCs labeled site-specifically with the cytotoxin of interest at a defined stoichiometry, starting with cGMP manufactured antibodies. This will dramatically reduce the time and cost of ADC manufacturing and characterization, and provide more homogenous, better-characterized, and safer products to patients. The broader impact/commercial potential of this project, if successful, will be novel applications for drug delivery as well as biotherapeutics. Due to the remarkable recent success of ADCs in the clinic, technologies for rapid and site-specific labeling of antibodies have a large market and are sought by companies discovering ADCs as well as CMOs manufacturing ADCs. Moreover, with the cost of a single course of treatment with ADCs escalating to>$100,000, there is an urgent need to find technologies that are able to meet this growing demand without increasing costs for payors. Beyond ADCs, site-specific labeling with our designer TPases will allow generation of companion diagnostics for antibody therapeutics to enable effective stratification of patient populations as well as imaging of tumor boundaries in surgical settings. In addition, the ability to conjugate proteins without modification or with minimal modification, will also allow the creation of immunotoxins/immunoenzymes where antibodies are tethered to potent protein toxins or enzymes that act catalytically within target cells. Lastly, the ability to make what are effectively designer protein ligases will allow the development of a toolbox of reagents, not unlike restriction enzymes for DNA manipulations, which will yield a valuable construction kit for the field of protein engineering.