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Impact of vector copy number on critical quality attributes of retrovirally engineered T cells
Scott M Norberg1, Rupali Gund2, Ekaterina Doubrovina2
1Center for Immuno-Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract:
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.
Insights
Higher vector copy number (VCN) in engineered T cells correlates with improved product purity and potency. This study found increased VCN enhanced T cell function without insertional oncogenesis risks in cancer therapy.
Area of Science:
- Cellular immunotherapy
- Gene therapy
- Oncology
Background:
- FDA-approved T cell therapies utilize retroviral vectors for T cell genome modification.
- Limited data exists on the impact of vector copy number per transduced cell (VCN) on critical quality attributes (CQAs) of these therapies.
Purpose of the Study:
- To investigate the effect of VCN on the purity and potency of E7 T cells, a T cell receptor (TCR)-engineered product for HPV-associated cancers.
- To assess the correlation between VCN and functional characteristics of engineered T cells.
Main Methods:
- Analysis of E7 T cell products from a clinical trial.
- Measurement of transduction efficiency, tumor recognition (IFN-γ production), and cytotoxic activity.
- Assessment of VCN in archived retention vials.
Main Results:
- Increased VCN positively correlated with enhanced functional characteristics, including transduction efficiency and tumor recognition.
- Higher VCN was associated with improved cytotoxic activity in real-time killing assays.
- Median VCN in archived samples was >5, with no observed cases of insertional oncogenesis.
Conclusions:
- VCN positively correlates with improved cell product purity and potency in retrovirally-engineered T cell therapies.
- Findings support the clinical safety of retroviral vector use, showing a low risk of insertional oncogenesis.
