The optimization of the high salt, low salt, equilibration, and elution buffers of the downstream process for the protein-a purification of cetuximab, a biosimilar, with phosphate and citrate buffer solutions

Two of the most vicious cancer types in humans are head and neck tumors. These tumors build vascular structures within to feed themselves and grow. The molecule Cetuximab inhibits the Epidermal Growth Factor receptors of these tumor cells. This way, with preventing them from building vascular structures, in the early stage treatments of these tumors, Cetuximab is promising hope with extended life expectancy and increased life quality. Nobel Pharmaceuticals, a company aiming to produce biosimilars of the Cetuximab molecule, needs to optimize the chemical process of purifying and producing the molecule to reach the 2000 liter production size for the market. This thesis has focused on the downstream process's first step, namely the buffer solution choice optimization. In this step, the Protein-A affinity chromatography has been performed in phosphate and citrate buffer solutions, the experiments have been repeated in analytical HPLC devices with smaller sizes and verified, and titer and yield calculations have been performed. Afterward, the protein, taken from the elution step, has been compared to the original molecule with its acidic, basic, and main variants. After all experiments and calculations, it has been found that the Protein-A chromatography performed with the phosphate buffer has performed above the 95% percent minimum expectancy of protein recovery. The proteins obtained from the phosphate buffer experiments have also scored highest in the cation exchange chromatography analysis, with the closest percentile values to the original molecule's acidic, basic and main variants.