Advances in clinical NK cell studies: Donor selection, manufacturing and quality control

Abstract

Natural killer (NK) cells are increasingly used in clinical studies in order to treat patients with various malignancies. The following review summarizes platform lectures and 2013-2015 consortium meetings on manufacturing and clinical use of NK cells in Europe and United States. A broad overview of recent pre-clinical and clinical results in NK cell therapies is provided based on unstimulated, cytokine-activated, as well as genetically engineered NK cells using chimeric antigen receptors (CAR). Differences in donor selection, manufacturing and quality control of NK cells for cancer immunotherapies are described and basic recommendations are outlined for harmonization in future NK cell studies.

Keywords: Clinical NK cell studies; ex vivo expansion; manufacturing of NK cell products; quality control.

Figure 1.

Evolution of tissue typing. Typing of KIR and HLA are important for donor selection because their polymorphisms affect NK cell function. HLA typing is done at a resolution that allows discernment of the KIR ligand groups in HLA-A, B, and C. KIR typing involves three levels: genotyping for gene content and B-scoring, phenotyping for gene expression, and allelotyping for allele polymorphisms.

Figure 2.

Modular quality control for NK cells. For NK cell phenotyping on accredited flow cytometer a backbone including the antibodies CD45, CD56, CD3, CD16, CD14 or CD14/DRAQ7 and live/dead staining such as 7-AAD or PI for NK cell identity should be accompanied by different variable drop in markers like NCRs or KIRs for specificity and potency. For NK cell functionality, the same backbone might be used in combination to intracellular staining or specific target labeling in case of effector: target cytotoxicity. NCR = natural cytotoxicity receptors; KIR = Killer immunglobuline like receptors.