Polymers for the Stabilization and Delivery of Protein Therapeutics
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Polymers for the Stabilization and Delivery of Protein Therapeutics


Proteins are an excellent therapeutic modality for the treatment of a wide range of diseases. When compared to traditional small molecule drugs, these therapies offer a number of advantages including selectivity and favorable therapeutic windows. However, proteins are inherently unstable molecules. Due to their reliance on tertiary structure for activity, proteins are often sensitive to a range of external stressors including temperature, pH change, light, and agitation which can lead to irreversible degradation or aggregation. Furthermore, after delivery, a number of in vivo clearance mechanisms exist such as the immune system, proteases, and renal filtration that can limit their desired effect. As a means to mitigate these challenges, polymers can be used to stabilize proteins against both external stressors and in vivo clearance mechanisms. In this dissertation, new polymeric methods for protein stabilization and delivery are presented. A large and growing field in biologics development are monoclonal antibodies. These drugs can be used directly as therapies for the treatment of a large number of diseases or as means to deliver small molecule drugs (in the form of antibody drug conjugates). In chapter 1, a literature review on antibody drug conjugates (ADCs) is presented with a focus on methods to improve the stability and delivery of the modality. As a contribution to this field, a new sequence-defined and hydrophilic platform for ADCs is presented in chapter 2. This strategy involves the use of iterative poly ethylene glycol (PEG) synthesis to create solubilizing scaffolds for hydrophobic payloads. In addition to increasing the efficacy of ADCs, stabilizing polymers can be used as conjugates to stabilize monoclonal antibodies. In chapter 3, trehalose polymers are demonstrated as a stabilizing motif for both Herceptin and its Fab fragment. Both the work in chapter 2 and 3 demonstrate the applicability of polymers in increasing the stability of antibody-based drugs. Chapter 4 outlines the work on stabilizing granulocyte colony stimulating factor (G-CSF) with trehalose polymers. Specifically, this research focuses on the optimization of the E. coli expression of G-CSF. After demonstrating an effective and scalable method for the production of the protein, a new strategy for selective conjugation is presented that utilizes a heterobifunctional benzaldehyde maleimide linker. We also demonstrate a new method for the preparation of protein nanogels in chapter 5. By using a photocleavable monomer, we show an effective strategy to produce non-covalent and active enzyme nanogels. This strategy is employed in the encapsulation of the enzyme phenylalanine ammonia lyase (PAL) for delivery through the digestive tract.

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