Genetically engineered T cell therapies are approved by the FDA for the treatment of various cancers. The cell products in these treatments are manufactured using retroviral vectors to insert an antigen-targeting receptor into the T cell genome. Limited data exist on how vector copy number (VCN) per transduced cell impacts critical quality attributes (CQAs) of retrovirally engineered T cell products. We investigated the effect of VCN on the purity and potency of E7 T cells, a T cell receptor (TCR)-engineered cell product that has shown safety and clinical activity in human papillomavirus (HPV)-associated cancers. An increased VCN correlated with enhanced functional characteristics, including transduction efficiency, tumor recognition as measured by IFN-γ production, and cytotoxic activity in real-time killing assays. We then analyzed archived retention vials from E7 T cell products from a clinical trial prior to FDA guidance on VCN limits. The median VCN was >5, and there were no cases of insertional oncogenesis. These findings demonstrate a positive correlation between VCN and improved cell product purity and potency and contribute to existing clinical data showing a low risk of insertional oncogenesis in retrovirally engineered T cell therapies.
Keywords: CAR T cell therapy; T cell receptor-T cell therapy; TCR-T cell therapy; VCN; adoptive T cell therapy; cell manufacturing; chimeric antigen receptor T cell therapy; secondary malignancy; vector copy number.
Published by Elsevier Inc.