059 Role of cryopreservation in the clinical delivery of T cell based adoptive cell therapies (ACT)

Abstract

The development of Adoptive Cell Therapy (ACT) based immunotherapies using either naturally-occurring or genetically engineered T cells to target tumours have reached a stage where the approach is delivering clinically significant results in: [1] gene engineered T cells using either Chimeric Antigen Receptors (CAR) in B cell lymphoma or tumour specific T cell receptors in metastatic melanoma or metastatic synovial cell Sarcoma; and [2] Naturally-occurring tumour specific T cells called Tumour Infiltrating Lymphocytes in metastatic melanoma. However, the current delivery of these treatments is often referred to as a “just in time” product ( i . e . where cell manufacturing, the hospital and patient are synchronised for the delivery of the ACT) and hence is not sustainable to treat suitable numbers of patients for either large scale multi-centre trials or to ultimately provide the treatment as a standard therapy. In order for effective reproducible treatments to be manufactured for ACT, the most significant challenge is maintaining the stability of the starting material, from the patient, prior to processing and the final product after formulation for infusion. In essence, GMP requires the manufacturing process to routinely maintain inter-product uniformity and hence minimise the impact of the manufacturing process on the final clinical outcome. In addition, by stabilising starting materials and products this also allows manufacturing sites to schedule production runs both of these points increase the likelihood that ACTs can be manufactured routinely. Aqueous solutions have a tendency to undercool, i.e . to cool significantly below their melting point before ice nucleation occurs. In addition, control of ice nucleation is recognised as a critical step in the cryopreservation of embryos and oocytes for IVF. Therefore, we assessed the effect of spontaneous or controlled ice nucleation on the viability and function of T cells either as starting materials such as Peripheral Blood Mononuclear cells (PBMC) or after in vitro expansion to provide supportive pre-clinical data T cells for ACT in early phase trials. In this study we demonstrated controlled ice nucleation is capable of improving the recovery of T cells from either frozen PBMCs or culture enriched T cells in cryovials, using both controlled-rate freezing and passive freezing. Analysis of culture purified T cells, expanded following controlled nucleation, showed that there was a significant improvement over spontaneous nucleation at either an early (96 hours) or at a later (14 days) time point. In addition, assessment of various cryopreservatives revealed that high serum content negated the benefits of controlled nucleation. These findings could be expected to improve the reliability and efficacy of GMP manufacturing for natural or genetically engineered T cell based ACTs. Controlled ice nucleation is also likely to improve the recovery of cryopreservation starting materials for personalised medicines, clinical delivery of cell therapies, and the quality of PBMCs in biobanks. Source of funding: University of Manchester, The Christie, UK Technology Strategy Board (Grant 130328 & MR/K500732/1), Kay Kendal Foundation & European Union FP7. Conflict of interest: Co-founder of Cellular Therapeutics Ltd. Ryan.Guest@manchester.ac.uk