Process Steps in Immune Cell Therapy Manufacturing

Isolation of particular T cell subsets from a heterogeneous population is the first step in immune cell therapy manufacturing. The efficient enrichment of T cell subsets includes both maximum yield and purity. Rigorous analysis of your cell populations for phenotype and viability as well as the lack of contaminating cell types is necessary to confirm that your isolation procedure is effective.

Expanding T cell cultures from the relatively small size of harvested samples to clinically effective scale requires optimized growth media and equipment. Ancillary materials including media and supplements should be GMP-grade and standardized for activity and reproducibility. The accurate addition of precise levels of growth factors should be confirmed with specific immunoassays. It is critical to achieve robust cell proliferation and activation and also to guard against overactivation and T cell exhaustion.

Cell engineering enables you to fine tune the effectiveness of your T cell therapy by introducing and deleting molecules that alter cell phenotype and function. There are multiple techniques for cell engineering including CRISPR/Cas9, viral transduction, and non-viral methods (e.g. TcBuster gene delivery system).

Cell therapy quality control has to be robust and consistent, because the cells are intended for human administration. The performance of QC methods must not jeopardize patient safety in any way. It is essential to confirm that cell products meet all critical quality attributes (CQA) at each step of the process. Cell therapies are classified as Advanced Therapy Medical Products (ATMPs) which are significantly more complex than purified pharmaceutical or biologic molecules. As living cellular treatments, they require more extensive characterization to assure efficacy and patient safety. Rigorous characterization methods reduce the risk of process failures that can arise if substandard cells are passed to the next stage of the process. These failures are extremely expensive and also prevent therapies from quickly reaching the patients who need them. Critical quality attributes (CQAs) are important to define early in process development and build into the manufacturing process. CQAs are the quality control parameters that are required for a product to pass to the next stage. They should reflect the cell therapy’s clinical indications to provide the most accurate indication possible of the product’s performance and safety. No one test can define the total quality attributes of a cell product. Orthogonal CQA testing methods analyze unrelated parameters of the product and may include physical characterization of the cells (e.g. surface phenotype, activation status, and viability), secretory profile, functional assays (e.g. cytolytic activity), and purity (e.g. undesired cell types and particulates).

The development of adoptive T cell therapies is advancing rapidly but still has considerable room for improvements in performance and safety. To this end, it is necessary to understand how T cell therapies perform after administration, both in preclinical animal models as well as in biopsy samples from treated patients. Analyzing the integrity and trafficking of your engineered T cell therapy in situ provides detailed information about infiltration and persistence in the tumor.