Technology assisted strategies for the synthesis of bioconjugates

Abstract

Over the past few years, one-third of the top 25 best-selling pharmaceutical drugs came off patent, and this year, the pharmaceutical industry is predicted to lose an additional $20 billion, which will stimulate more growth in the generics sector. Due to the rising costs of bringing a new molecular entity (NME) to market, pharmaceutical companies are investing in technology that will enhance the drug development process by reducing time, energy, manpower, and waste in these processes. Furthermore, there is a push in the industry to produce biological conjugates, which have shown enhanced targeting to receptors in the body. This work presents three projects that utilize technology for the synthesis of bioconjugates. The first is the synthesis of steroid-porphyrin conjugates as potential photodynamic therapy (PDT) agents for breast cancer. PDT has not been exploited to its fullest potential due to issues with effective accumulation. To enhance selectivity, estradiol, which targets the overexpressed estrogen receptor in breast cancer, was conjugated to a photosensitizer, pyropheophorbide. Synthesis, including flow reactions, and biological assays will be presented. I have also investigated the synthesis of antibody-drug conjugates (ADC) via continuous flow chemistry. ADCs are a promising family of compounds that have been used for selectively targeting tumor cells. One setback with the construction of these conjugates is the ability to couple three different components, antibody, linker, and drug, while predicting efficacy of the whole. I have been able to produce protein-drug conjugates in batch, microwave, and flow conditions with great success. Initial experimentation has shown reproducible and tighter distribution profiles of tagged-drug species to proteins in proof-of-principle reactions. The final project involves the production of triazoles in a one-pot, two-step continuous flow process. Azides have been avoided in the pharmaceutical industry due to the inability to scale up in a safe and effective manner. Triazole formation has been accomplished from the corresponding bromides and amines using varying azide sources to obtain the reactive intermediate before ring closure. Improvements in reaction times and safety profiles have been observed with this reaction, and plans to form the corresponding triazolopyrimidines will be discussed. Overall, this dissertation will give an overview of bioconjugations via novel technology, namely continuous flow chemistry, for drug discovery applications.