RESUMO
In clinical gene transfer applications, lentiviral vectors (LV) have rapidly become the primary means to achieve permanent and stable expression of a gene of interest or alteration of gene expression in target cells. This status can be attributed primarily to the ability of the LV to (1) transduce dividing as well as quiescent cells, (2) restrict or expand tropism through envelope pseudo-typing, and (3) regulate gene expression within different cell lineages through internal promoter selection. Recent progress in viral vector design such as the elimination of unnecessary viral elements, split packaging, and self-inactivating vectors has established a significant safety profile for these vectors. The level of GMP compliance required for the manufacture of LV is dependent upon their intended use, stage of drug product development, and country where the vector will be used as the different regulatory authorities who oversee the clinical usage of such products may have different requirements. As such, successful GMP manufacture of LV requires a combination of diverse factors including: regulatory expertise, compliant facilities, validated and calibrated equipments, starting materials of the highest quality, trained production personnel, scientifically robust production processes, and a quality by design approach. More importantly, oversight throughout manufacturing by an independent Quality Assurance Unit who has the authority to reject or approve the materials is required. We describe here the GMP manufacture of LV at our facility using a four plasmid system where 293T cells from an approved Master Cell Bank (MCB) are transiently transfected using polyethylenimine (PEI). Following transfection, the media is changed and Benzonase added to digest residual plasmid DNA. Two harvests of crude supernatant are collected and then clarified by filtration. The clarified supernatant is purified and concentrated by anion exchange chromatography and tangential flow filtration. The final product is then diafiltered directly into the sponsor defined final formulation buffer and aseptically filled.
