CiMaas successfully expands Natural Killer (NK) cells to clinically relevant numbers using a 2-week protocol. Starting from 200 ml peripheral blood, NK are expanded to numbers meeting the expected clinically required 10.E8 cells/kg, with multiple infusions. This makes the expansion method developed directly applicable for clinical application of the produced NK cells in anti-cancer therapies. 

Recent data demonstrate that the viability upon thawing is high and remains so over a 4-day period after thaw. Thawed and recovered NK cells show a good killing capacity for different cancer cell lines (blood borne as well as solid tumors). Moreover, > 90% of the cells express CD16, the activating ligand for antibodies. NK cells and antibodies synergize in killing capacity. 

The cells have been made from frozen peripheral blood mononuclear cells after HLA typing. This makes an ‘off the shelf’ approach feasible and allowing optimal HLA selection for NK cell activity in specially selected patients. 

Additional supportive pre-clinical studies are planned to validate the activity of these cells in 3D tumor models and tumor bearing mice. The manufacturing protocol is GMP compliant and almost entirely closed, which reduces the risk of batch failure.

The company owns a certified cell therapy manufacturing facility for the GMP production of clinical trial material. 

CiMaas will perform a clinical trial in hematological malignancies in 2023. CiMaas is open for further partnerships on NK cell-based therapies with industry partners or for additional cancer indications using NK cells produced under GMP compliancy for which the company has a permission for ATMP production.

As CiMaas believes in collaboration, we would like to provide these cells to selected (academic) research centers interested in studying them in their in vitro cancer research and in vivo tumor models. Current collaborations exist with the Maastricht University and the University of Utrecht in breast cancer, based on a grant from Health Holland and the Dutch Cancer Foundation.  

Further information on quality, capacity, available cell numbers and forms of collaboration can be obtained directly from the company. Please email to