The process is a selective expansion and activation of NK-cells from a mixed leukocyte population. CellProtect is an autologous product; hence a new batch is generated for each patient. 

During the manufacturing of CellProtect, peripheral blood mononuclear cells (PBMCs) are expanded and activated in a bioreactor. The expansion time is 20-25 days, and the cell preparation harvested at the end of the expansion is enriched in NK cells with cytotoxic activity.

CellProtect is formulated in cryo-medium and filled into cryo- bags in doses tailored to the patient and stored frozen.  After release, the frozen cells are delivered to the clinic, where they are thawed and infused without any further processing. 

Up to 8 years stability of the CellProtect product during storage in liquid nitrogen has been demonstrated. Cell viability and cytotoxicity assay are considered stability-indicating methods.

Nonclinical pharmacology studies with CellProtect and other human and murine NK cell preparations include in vitro studies of cytopathic (cell killing) effect, cell phenotype and cytokine release and in vivo studies examining anti-tumour efficacy in mouse models of human and murine tumours. 

In vitro studies with CellProtect demonstrated its ability to lyse autologous MM cells as well as K562 human leukaemia cells and RPMI8226 human myeloma cells, with no significant toxicity against non-MM (CD138-) cells, CD34+ cells from bone marrow or autologous PHA blasts. Cell expansion did not significantly alter cytokine expression but did increase expression of ten activating receptors, including NKG2D and the natural cytotoxicity receptors NKp30, NKp44 and NKp46, and two inhibitory cell surface receptors. 

Supportive pharmacology studies with other ex vivo expanded NK cell preparations demonstrated in vitro cytotoxicity of expanded NK cells from B-cell chronic lymphocytic leukaemia (B-CLL) patients and healthy human donors against K562 cells. Similarly, NK cells from non-challenged or 5T33MM tumour-bearing mice showed marked in vitro cytotoxicity against mouse lymphoma (YAC-1) cells and syngeneic 5T33MM cells, but no significant toxicity against lipopolysaccharide (LPS) blasts, splenocytes, hepatocytes or normal bone marrow cells.

In vivo pharmacology studies demonstrated an anti-tumour effect of ex vivo expanded NK cells from healthy human donors in the K562 human myelogenous leukaemia model in severe combined immunodeficiency disease (SCID) mice and an anti-tumour effect of activated mouse NK cells in the 5T33 murine myeloma model in C57BL/KaLeRij mice.

The biodistribution of transfused effector cells is critical for cell therapy approaches, with migration to tumour sites considered a prerequisite for therapeutic efficacy in cancer patients. Biodistribution studies in 5T33MM tumour bearing mice inoculated with autologous NK cells showed co-localization of NK cells and MM cells in the liver, spleen and bone marrow suggest that adoptively transferred cells are homing to tumour-rich organs. NK cells were detectable in all three tissues up to 40 days after administration. 

Although no formal toxicology studies have been conducted with CellProtect, supportive data is available from a nonclinical pharmacology study in tumour-bearing SCID mice administered 20 x 106 human ex vivo expanded clinical grade NK cells by the i.v. route, where no signs of toxicity or other unwanted side effects were seen during an observation time of 100 to 130 days.