Development of activatable antibodies targeting CD133 for enhanced cancer stem cell selectivity


Bentanachs Raset, Jordi


Glioblastoma multiforme (GBM) is the most malignant primary brain tumor and is currently incurable. One of the main obstacles to the treatment of this type of tumor is the presence of cancer stem cells (CSC), which have chemoresistance and the ability to induce new tumors once the treatment is finished. Therapies targeting CSC have several drawbacks, such as the fact that receptors overexpressed on these cells are also present on healthy stem cells. In order to face this problem, we will generate a nanotherapy that selectively administers the tumor. To do this, we are going to create an activatable antibody that binds to CD133, the most studied extracellular marker in CSCs. This final degree project is part of a European project that aims to generate a targeted gene nanotherapy capable of eliminating CSCs for the treatment of GBM. First, I will review the available strategies to make the antibodies activatable, and then I will describe and discuss my contribution to generating an activatable anti-CD133 antibody.
In the first part of this study, we review the different strategies for developing activatable antibodies and their potential in therapeutic applications, as well as in diagnostics, chromatography, and basic research. Activatable antibodies are conventional antibodies designed to control their activity through specific stimuli. Strategies for conferring such a response to the stimulus can range from modification of a single amino acid to more drastic modifications that alter the entire structure. A wide range of stimuli have been used to control antibody activity, including proteases, phosphatases, pH, light, effector molecules, ions, and temperature.
In the second part of this study, we applied one of the antibody activation strategies with the greatest potential in immunotherapy to generate a protease-dependent anti-CD133 single chain antibody fragment (scFv). This technique is based on masking the antigen-binding region with a peptide, which mimics the epitope, which binds to the antibody through a sequence sensitive to tumor proteases. In this project, three protease-dependent scFv variants are cloned and one of them is expressed and purified. Finally, the first steps to evaluate the binding of anti-CD133 scFv in cells are presented.



Oller Salvia, Benjamí


IQS SE - Undergraduate Program in Biotechnology