Gene Delivery Technologies To Create Tomorrow's Cell Therapies
By Tara Fernandez, Product Manager, Pre-clinical Discovery Products for Cell & Gene Therapies, Precision NanoSystems
As more cell-based therapies transition towards the market, hurdles surrounding safety, efficacy, and manufacturing are becoming increasingly apparent. The advancement of gene delivery technologies is fundamental to driving more clinical prospects of cell therapies.
The art of gene delivery uses physical, chemical, or viral means to introduce genetic material into cells, thereby amplifying or enhancing their natural functions and harnessing their full therapeutic potential. These techniques use relatively aggressive means to disrupt the cell membrane (from electrical currents to surface charged lipids) and introduce macromolecular cargoes into cells, thereby triggering directed cytoplasmic events.
Incorporating such transfection techniques into manufacturing workflows for cell therapies is no easy feat. To date, a one-size-fits-all gene delivery approach that ticks all of cell therapy’s safety, efficacy, and regulatory boxes has yet to be established.
The currently available options are often inefficient, costly, time consuming or pose dangerous safety risks to patients receiving treatment. These challenges, among others, stand in the way of cell therapies becoming more widely accessible.
So, what does the design space for an optimal gene delivery platform look like? What does it need to be able to do to enable the creation of the next generation of cell therapies as completely autonomous living drugs?
Strong Gene Transfer, Gentle on Cells
A critical aspect of any therapeutically relevant cell engineering system is the ability to generate robust changes in cells without compromising cell health or giving rise to off-target effects. An ideal system should not just deposit payloads in the intracellular space, but also can transmit genes directly into the nucleus. For chimeric antigen receptor T-cell (CAR T) production, for example, CAR-encoding genes need to be integrated into the genome such that CAR is continually expressed on the T-cell surface as cells are expanded. The next frontier of allogeneic, off-the-shelf cell therapies also requires nuclear access for gene-editing machinery to knock out donor genes responsible for immune responses in the recipient.
Following this genetic manipulation step, it is imperative that the sensitive cellular end-products retain their physiological properties such that they are safe and therapeutically beneficial to patients.
Realistically, this may be easier said than done. Emerging evidence shows that gene delivery techniques impact cells on a much deeper level than is typically detected by conventional cell viability assays. Transcriptomic profiling of electroporated CAR T-cells, for instance, reveals dysregulated expression patterns of several key genes and altered functional pathways.
Precision, Control and Versatility
A transfection tool that could deliver standardized, tunable amounts of genetic material to each individual cell would take cell customization to the next level. This would greatly assist cell therapy developers in ensuring the final cell therapy product meets stringent quality control benchmarks. In the same vein, more accuracy and predictability at the ex vivo gene delivery stage would pave the way for unprecedented personalized cell therapies: completely tailor-made to generate well-defined clinical outcomes and meet distinct patient requirements.
Besides being gentle and controlled, best-in-class transfection modalities of the future also need to be flexible and adaptable to a wide array of target cell types. The repertoire of cell-based therapies entering the clinical trial phase is continually expanding to encompass more stem, immune and somatic cell types, each with their own nuances for optimal gene delivery.
Adding another layer of complexity is the growing array of cell-modifying payloads available for cell therapy applications. The first FDA-approved cell therapy, YESCARTA™ uses a lentivirus to deliver CAR-encoding nucleic acid to T-cells. Looking forward, advancements in CAR-T manufacturing platforms also have to accommodate the ever-expanding reprogramming toolkit which now includes tranposons, homing endonucleases, CRISPR-Cas9, TALENs, and zinc finger nucleases.
Accelerated Commercialization of Advanced Cell Therapies
Next, a fully scalable gene delivery platform that can be used at every stage of the cell therapy lifecycle, from discovery to clinical manufacture would be a tremendous development.
Consider the development pathway of an engineered stem cell product. During the discovery stages, a transfection technique amenable to high-throughput screening is required. As development continues, larger quantities of cells need to be genetically modified to perform additional assays and animal studies. Finally, for trials and subsequent clinical manufacturing, bioreactor scale gene transfer needs to be performed. At present, gene delivery techniques need to be validated and optimized to match the required scale at every stage gate in the pipeline.
A big step-up would be a bench-to-bedside transfection system that uses cGMP-grade materials and seamlessly scales up to meet commercialization requirements. As a bonus, a process that is fast, cost effective, easy to use and lends itself to automated, closed, and even point-of-care biomanufacturing systems, would be a model of excellence.
The Future of Cell Engineering
Emerging biotechnologies are helping to reimagine traditional practices in the cell therapy industry. The steady rise of non-viral gene vectors, such as nanotechnology-based methods are coming into the spotlight as viable alternatives to conventional methods. Nanoparticles encapsulate nucleic acids and by hijacking natural endosomal pathways, effectively transfer genes in vivo with minimal effects on cellular integrity. As these technologies continue to evolve, nanoparticles designed to target and engineer specific cell populations in vivo may someday revolutionize cell therapy manufacturing as we know it, by completely removing the need for centralized manufacturing facilities altogether.
Increasingly elegant tools for genetically manipulating cells are shaping what’s in the cards for future cell therapies. Built upon a need for safe, highly controlled, and scalable gene delivery, these innovations continue to push the boundaries, de-risk end products at the clinical level and maximize cell therapy manufacturing yields. Still, out-of-the-box thinking, interdisciplinary efforts, and a deeper understanding of the molecular mechanisms involved are necessary to deliver the genes that create tomorrow’s cell therapies.