Abstract 3752: FATE-NK100: A novel NK cell-mediated cancer therapy
Authors: Cichocki Frank , Valamehr Barham , Bjordahl Ryan , Zhang Bin , Sarhan Dhifaf , Cooley Sarah , Blazar Bruce , Rezner Betsy , Rogers Paul , Green Chad , Abbot Stewart , Shoemaker Daniel , Wolchko Scott , Miller Jeffrey S. 
Published: July 2017

Natural killer (NK) cells are innate lymphoid cells that mediate immune responses against pathogens and cancer. Human NK cells are distinguished by the surface phenotype CD3-CD56+, and maturation of CD56dim NK cells is associated with acquisition of CD57. Rather than being an immunosenescence marker, CD57 acquisition represents a shift toward greater effector function, including increased CD16 signaling (Fc receptor responsible for triggering antibody-dependent cellular cytotoxicity), more potent cytotoxicity and enhanced inflammatory cytokine production after target cell engagement.

The main challenge in enriching for CD57+ NK cells using current ex vivo expansion protocols is that interleukin (IL)-15, the cytokine that drives NK cell proliferation and is critical for NK cell survival, preferentially expands less mature NK subsets that fail to terminally differentiate in culture. Our group has developed a novel NK cell expansion method that overcomes this barrier. Peripheral blood mononuclear cells from are depleted of CD3+ T cells and CD19+ B cells and cultured for 7 days with IL-15 and a small molecule inhibitor of glycogen synthase kinase 3-beta (GSK3β), a multifunctional kinase downstream of the PI(3)K pathway. Compared to vehicle control, addition of the GSK3β inhibitor led to a substantial increase (2.2-fold ± 0.19, n=23, p&lt;0.0001) in the CD57+ NK cell population, and total CD3-CD56+ NK cells were highly enriched (90.9% ± 2.2) relative to pre-culture CD3/CD19 depletion (23.3% ± 2.5) (p&lt;0.0001). We used a high-resolution imaging approach to analyze in vitro NK cell-mediated killing of the ovarian tumor cell line SKOV-3 and the lung carcinoma line A549. We demonstrate that NK cells from CD3/CD19-depleted peripheral blood products cultured for 7 days with the GSK3β inhibitor exhibit significantly more rapid killing kinetics and overall tumor killing relative to NK cells cultured for 7 days with IL-15 and the vehicle control. Superior tumor control of NK cells cultured with IL-15 and the GSK3β inhibitor was also observed against SKOV-3 tumor cells in a murine xenogeneic adoptive transfer model that included IL-2 injections.

We have scaled our process to manufacture a GMP product (referred to as FATE-NK100) for clinical use. Using an apheresis product from a donor containing 21.5 x 108 CD57+ NK cells, we achieved 6.4-fold NK cell expansion resulting in a final GMP-grade product containing 158 x 108 CD57+ NK cells. The cytotoxicity of these ex vivo expanded NK cells in response to SKOV-3 cells is superior to that of CD3/CD19-depleted haploidentical NK cells activated overnight with either IL-2 or IL-15 (representing the NK products used in current clinical trials). These data have been presented to the FDA in preparation for a clinical trial of FATE-NK100 in lymphodepleted patients with advanced AML anticipated for Q1 2017.

Citation Format: Frank Cichocki, Barham Valamehr, Ryan Bjordahl, Bin Zhang, Dhifaf Sarhan, Sarah Cooley, Bruce Blazar, Betsy Rezner, Paul Rogers, Chad Green, Stewart Abbot, Daniel Shoemaker, Scott Wolchko, Jeffrey S. Miller. FATE-NK100: A novel NK cell-mediated cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3752. doi:10.1158/1538-7445.AM2017-3752