The cell therapy industry’s biggest challenge is in manufacturing. Technologies are needed to support expansion of large numbers of cells for commercial production. A number of sources are presenting options: e.g., standard two-dimensional tissue cultures that “grow up” to Corning HYPERFlask and CellSTACK or Nunc Cell Factory systems; hollow-fiber–based equipment; and disposable bags and traditional stirred-tank bioreactors. Each has its place and application, but how can companies choose among them? Where and when do they initiate scale-up process development with limited resources and intense focus on clinical demonstration of therapeutic benefits?
The simplest way to move forward is scaling out rather than up. During lean and dry years, this might indeed be the best approach. It can take a company through clinical trials with minimal scale-up efforts, mainly related to fluid transfer and plastic handling. But lot-size limitations and associated costs in labor, cleanroom footprint, and incubator space can make this a costly choice. Change is exponentially more difficult to introduce after late-stage clinical trials and BLA approval. True scale up should be built into process development from an early phase — arguably, in preclinical development — to help ensure the ability to bring data forward without needing to redesigning flasks. Opportunities for more efficient scaling will present themselves. Companies with the foresight to take risks on novel approaches may be rewarded with commercially viable processes.
Flow Cytometry and Cell Therapy
Flow cytometry was a cutting-edge tool 25 years ago. The instruments were still fairly difficult to use, requiring dedicated operators and an entire room with ancillary support equipment — with a budget of several hundred thousand dollars. By the early 1980s, cell therapies were in clinical trials with a better understanding of their potential impact, and we had learned more about immune compatibility, and tools for cell purification (e.g., magnetic particles, cell sorters, and monoclonal antibodies) were starting to make clinical-scale cell separation possible. Flow cytometry and cell therapy have progressed in parallel toward simplification, robustness, and increasing capabilities. Only recently, however, have both undergone a true revolution.
Modern cytometers have improved sensitivity, throughput, and rare-event detection. Instrument speeds are increasing, and the purity of sorted cells continues to improve. Increasingly sophisticated data interrogation and safeguards are pushing this technology closer to true clinical utility. Cell therapies came to the forefront after approvals for TiGenix in Belgium and Dendreon in the United States. Phase 2 and 3 trials for cell therapy are recruiting, and applications are growing monthly. How will cytometry and cell therapy work together in the future?
As an analytical tool, cytometry will help in development. It should even be critical to cell therapy commercialization.
Better than any other platform, it can provide the high-quality, sensitive data required for lot release of single-cell suspensions.
As cell therapy developers create platforms to treat the masses, however, it’s hard to envision clinical cell sorting as more than a niche player. It still involves too many inconsistencies and too much time and money to become a pivotal technology for most cell therapy developers. Other technologies will take the place of the behemoth that is today’s cell sorter, and they will be smaller, faster, and more cost effective.
$1,000 Genome: A Cell Therapy Enabler?
Much press and excitement is dedicated to the impact of next-generation sequencing, the race to the “$1,000 genome,” and the healthcare revolution it will enable. The capability of these new techniques is being uncovered in some remarkable ways and may address some key gaps that cell therapy developers currently face when addressing common regulatory questions such as product characterization and safety.
Gene expression is a common method for mapping important signaling pathways indicative of cell identity in specific cell populations. Next-generation sequencing techniques have been successfully applied to extend this to a single blastomere. That offers remarkable accuracy and sensitivity lost to conventional techniques but critical to defining cell characteristics. Extending next-generation sequencing techniques further, some researchers have characterized the entire epigenome of embryonic stem cells relative to fibroblasts, finding key differences related to the stage of cell differentiation.
A further application has been in de novo identification of latent viral contamination through bioinformatics-based genetic similarity searches. The FDA’s Vaccines and Related Biological Products Advisory Committee recently met to consider work by Eric Delwart, who used these techniques to identify the presence of porcine circovirus 1 in GlaxoSmithKline’s Rotarix vaccine for rotavirus. Genetic stability of cells has also been assessed using digital karoytyping, offering a rapid and cost-effective alternative to a traditionally laborious process.
Just as advanced analytical techniques (e.g., peptide mapping and glycosylation analysis) allowed monoclonal antibodies to move from “process as product” to more analytically defined and therefore controlled products, next-generation sequencing techniques could offer the opportunity for similar maturation in cell therapies, with commensurate shortening of the time to product approvals.
Eric Roos is cell therapy business development leader for stem cells, and Brian Newsom is cell therapy business development leader at Invitrogen Corporation. Paul Pickering is general manager of cell therapy systems for Life Technologies. Their comments were originally posted online at Invitrogen’s “Cell Therapy Central” community (http://cellularmojo.community.invitrogen.com/community/celltherapycentral).