QC and Release Testing of Vector and Cell Clinical Gene Therapy Products

Division Of Basic Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

The release of clinical vector/virus and cell products requires the execution of several concurrent, time sensitive assays by the Surgery Branch Quality Control Unit. These assays demonstrate appropriate conformance to specification metrics of products manufactured both at the Surgery Branch and from external labs such as Contract Manufacturing Organizations (CMOs) or Cooperative Research and Development Agreement (CRADA) partners. The Certificate of Analysis (COA) provides the specifications for product use. These assays are complex cell-based, multi-day assays that are executed under time constraints to meet clinical patient treatment schedules. The primary focus of the Branch currently is individualized treatments/products; thus each virus or cell product is intended for a single, unique patient. Every vector and cell product must be tested (in contrast to bulk testing for a product administered to multiple patients) independently. Some reagents such as the antigen presenting cells (APCs) required for specificity/potency assays (a cell-based assay) are generated and assessed in the SB-QCU for use in the release testing. Unique APCs must be generated for each individualized therapy and can take >1 month to generate and test. To date, the unit has generated and banked B cells for every vector tested (>100 banks). Release of Vector: The assays/tests required to demonstrate that a vector produced at the SB or other facility is appropriate, safe and meets specifications for clinical use are: vector titer, TCR specificity/potency and presence (absence) of replication competent retrovirus, residual plasmid, residual benzonase endonuclease, endotoxin and sterility (microbiology and mycoplasma). All assays except the sterility assays are performed by the SB QCU group. The SB QCU, since its inception in 2018, has performed the suite of assays on >120 individual vector products (20 since the last annual report). In addition, the QCU reports on stability of vector product,providing data supporting that material manufactured and stored correctly can be used safely for many years. Release of Cell Products: The assays required to demonstrate that cellular products manufactured at the SB are appropriate, safe and meet specifications for clinical use are: transduction efficiency, TCR specificity/potency, presence (absence) of replication competent retrovirus, residual plasmid, residual benzonase endonuclease, vector copy number (per cell), endotoxin and sterility (microbiology and mycoplasma). All assays except the sterility assays are performed by the SB QCU group. The SB QCU, since its inception in 2018, has performed the suite of assays on >80 individual cellular products (14 since the last annual report). The QCU has recently added "For information only" testing to its repertoire (tests include transduction efficiency and specificity/potency) which is in-process testing used to guide manufacturing decisions for the cell production facility. The Unit has supported 3 productions to date with this new testing. An unfortunate consequence of personalized therapies with long lead times from discovery of patient specific TCRs through to a vetted patient treatment (>6 months) is that many vector products are made and tested but not used as the patient becomes ineligible due to disease progression before the treatment is ready. This is the primary cause for the discrepancy in vectors tested for clinical use versus patient products generated for treatment/infusion. Other unique factors of the trials supported by this project are that some vectors are made for allogeneic use (TCR identified in another patient, but vector used in manufacturing of patient autologous cells for treatment) as well as some TCRs are transferred to clinical vector production but the data generated by the research team is either incomplete or cannot be replicated using the GMP-qualified assays. New QCU Assays: The QCU paused work supporting a new IND developing novel cell-based assays to detect expression on controllable cassettes to characterize the autologous novel cell products to be generated and generate defensible specifications for the Certificate of Analysis for several months and restarted this project in March 2025. A cell-based assay to reliably detect and quantify (FACS) an inducible/degradable gene product (controllable) has been developed. Work is ongoing to develop molecular assays to quantify functional viral titers.