Guest commentary: Implications of cGMP for CRISPR/Cas9 cellular therapy

CRISPR/Cas9 offers the hope of a cure for various maladies, including genetic diseases and cancers, but current Good Manufacturing Practices still matter in handling this therapeutic avenue

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Many current therapeutic treatments are not able to address the underlying cause of a disease, alter its course or reverse damage that has already occurred. Cellular therapies offer the power of the human body to heal and regenerate itself. Regulatory precedents for cellular therapy products continue to evolve for a widening array of product types. An exciting new discovery of clustered regularly interspaced short palindromic repeat (CRISPR) technology, when incorporated with cellular therapy, may lead to the cure of many diseases.
CRISPR is a naturally occurring defense mechanism found in a wide range of bacteria. The microbial defense system has been developed based on its ability to bring the endonuclease Cas9 to specific locations within complex genomes. CRISPR/Cas9 is a highly accurate gene-editing technology that allows for the modifications of specific parts of a genome by altering sections of the DNA sequence.
CRISPR/Cas9 offers the hope of a cure for various maladies, including genetic diseases and cancers. The CRISPR/Cas9 medical cellular therapies involve removing cells from the body, modifying their DNA and administering them to the patient. These modified cells are able to either replace or attack diseased cells. Medical cellular therapies are required to demonstrate quality, safety and efficacy standards to obtain a marketing authorization. Medicinal cellular therapy products are regulated as drugs, devices and biological products, which adds the regulatory requirement of manufacturing under cGMP conditions.1-9
Supply and demand...and quality
With the high value of CRISPR/Cas9 source cell material, having ample amounts for process-development and validation of the manufacturing processes is an industry challenge. Furthermore, limited shelf life and quantity of cells can complicate quality control testing and stability determinations.
Defining critical quality attributes (CQAs) for these products and developing assays for their potency are essential to the commercialization of these cellular therapy products. CRISPR/Cas9 source cells are characterized based on the presence of surface markers, size and combinations of attributes associated with cell source and mode of action.
The clinicians who perform the CRISPR/Cas9 source cell collection procedures are typically not trained in current Good Manufacturing Practices (cGMP) regulations. Collection documentation should become part of the cGMP record, including any electronic data generated from the collection equipment and any on-site testing. CRISPR/Cas9 cell manufacturing location depends on the type of cell product and the product’s application. Whether a bedside point-of-care or a centralized manufacturing model is most appropriate should be based on indication and the stability of the product.
Location matters
CRISPR/Cas9 cell therapy manufacturing performed offsite from the collection location requires strict control in cGMP facilities. This includes the manufacturing space, the storage warehouse for raw and finished product and laboratory areas.10 CRISPR/Cas9 cellular therapy manufacturing facilities must be designed for aseptic processing. Development of fully enclosed manufacturing equipment and built-in controls for in-process testing is optimal for cellular processing.
Feedback automation processing would address the variability of CRISPR/Cas9 source cell properties with a manufacturing process that is flexible and adaptable to ensure that the end products are of the same quality and consistency. The feedback can control culture conditions in-process based on real-time measurements of CQAs.11 The integration of in-line assays and measurements for CQAs, as well as rapid measurements of potency, efficacy and safety parameters, are important elements for automation of the cell manufacturing process and will enable the establishment of robust CQAs. Each batch of a CRISPR/Cas9 cellular therapy product should pass very specific tests unique to the characteristics of the product. Furthermore, extensive characterization of the product is essential for proper process validation and the development of in-process and release testing specifications.
The shipment of cellular therapy products needs to be validated and temperature-monitored. Chain of custody and cellular environmental condition records should continue from collection through to administration.
Further considerations
CRISPR/Cas9 cells are dynamic and can continue to grow, differentiate, migrate and interact within the body. Characterization of the cell population prior to administration does not fully describe the phenotypes and genotypes of cells in the patient after CRISPR/Cas9 cellular treatment.
Characterization and CQAs should be redefined based on feedback from patient data and improved understanding of mechanisms of action as patients are monitored post-treatment. Using post-treatment patient data to understand the most effective therapeutic cells may lead to decreased numbers of cells necessary for treatment and manufacturing timelines.
Due to their ability to alter DNA, CRISPR/Cas9 cellular therapies offer the possibility to move beyond conventional disease treatment by addressing the underlying cause of disease, altering its course, or reversing damage that has already occurred. The transitions from discovery, to research and development, to commercially manufactured products, brings the challenge of the regulatory requirements for incorporating cGMPs into the collection, production and delivery of these products.
These developments will allow for CRISPR/Cas9 cellular therapy to become increasingly available to patients and will offer new treatments and the hope to cure many diseases.

Dr. Buytaert-Hoefen completed her master’s and doctoral degrees in neuroscience at the University of Colorado at Boulder and completed two post-doctoral fellowships at the University of Colorado Health Sciences Center, where she specialized in embryonic and adult stem cell research. She then entered industry with a position as a lead scientist at Navigant Biotechnologies, after which she accepted a position as a consumer safety officer at the FDA, where she specialized in pharmaceutical inspections with an emphasis on biotechnology and sterile processing. Currently, as a consultant at PAREXEL, she works closely with clients to develop and implement effective compliance solutions in accordance with client needs. She performs GXP audits, conducts laboratory data review including chemistry, microbiology and data integrity assessments.
1. PHS Act 42 U.S. Code § 262 - Regulation of biological products.
2. EudraLex, The Rules Governing Medicinal Products in the European Union, Volume 4 EU guidelines for Good Manufacturing Practice for Medicinal Products for Human and Veterinary Use, Annex 2, Manufacture of Biological active substances and Medicinal Products for Human Use , 2012.
3. EDQM, Guide to the quality and safety of tissues and cells for human application, dated 2017.
4. 21 CFR PART 1271, Human Cells, Tissues, and Cellular and Tissue-based Products.
5. 21 CFR PART 600, Biological Products.
6. 21 CFR PART 200, General Drug.
7. Regulation (EC) No 1394/2007 of the European Parliament and of the Council, 13 November 2007.
8. FDA Guidance for Industry Human Somatic Cell Therapy and Gene Therapy, March 1998.
9. Directive 2004/23/EC of the European Parliament and of the Council of 31 March 2004.
(human tissue and cells standards).
10. WHO good manufacturing practices for pharmaceutical products: main principles, Annex 2.
11. FDA Guidance for Industry PAT — A Framework for Innovative Pharmaceutical Development, Manufacturing, and Quality, Assurance, 2004.

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