Objective Natural killer (NK) cells represent a powerful immunotherapeutic target as they lyse tumors directly, do not require differentiation, and can elicit potent inflammatory responses. The objective of these studies was to use an IL-15 super-agonist complex, ALT-803 (Altor BioScience Corporation), to enhance the function of both normal and ovarian cancer patient derived NK cells by increasing cytotoxicity and cytokine production. Methods NK cell function from normal donor peripheral blood mononuclear cells (PBMCs) and ovarian cancer patient ascites was assessed using flow cytometry and chromium release assays +/− ALT-803 stimulation. To evaluate the ability of ALT-803 to enhance NK cell function in vivo against ovarian cancer, we used a MA148-luc ovarian cancer NOD scid gamma (NSG) xenogeneic mouse model with transferred human NK cells. Results ALT-803 potently enhanced functionality of NK cells against all ovarian cancer cell lines with significant increases seen in CD107a, IFNγ and TNFα expression depending on target cell line. Function was also rescued in NK cells derived from ovarian cancer patient ascites. Finally, only animals treated with intraperitoneal ALT-803 displayed an NK dependent significant decrease in tumor. Conclusions ALT-803 enhances NK cell cytotoxicity against ovarian cancer in vitro and in vivo and is able to rescue functionality of NK cells derived from ovarian cancer patient ascites. These findings suggest that ALT-803 has the potential to enhance NK-cell-based immunotherapeutic approaches for the treatment of ovarian cancer.
Objective: Natural killer (NK) cells are lymphocytes well suited for adoptive immunotherapy. Attempts with adoptive NK cell immunotherapy against ovarian cancer have proven unsuccessful, with the main limitations including failure to expand and diminished effector function. We investigated if incubation of NK cells with interleukin (IL)-12, IL-15, and IL-18 for 16 hours could produce cytokine-induced memory-like (CIML) NK cells capable of enhanced function against ovarian cancer. Methods: NK cells were preactivated briefly with IL-12, IL-15, and IL-18, rested, then placed against ovarian cancer targets to assess phenotype and function via flow cytometry. Real-time NKcell-mediated tumor-killing was evaluated. Using ascites cells and cell-free ascites fluid, NK cell proliferation and function within the immunosuppressive microenvironment was evaluated in vitro. Finally, CIML NK cells were injected intraperitoneal (IP) into an in vivo xenogeneic mouse model of ovarian cancer. Results: CIML NK cells demonstrate enhanced cytokine (IFN-γ) production and NK-cellmediated killing of ovarian cancer. NK cells treated overnight with cytokines led to robust *
We improved the bispecific antibody platform that primarily engages natural killer (NK) cells to kill cancer cells through antibody-dependent cellular cytotoxicity (ADCC) by adding IL-15 as a crosslinker that expands and self-sustains the effector NK cell population. The overall goal was to target B7-H3, an established marker predominantly expressed on cancer cells and minimally expressed on normal cells, and prove that it could target cancer cells in vitro and inhibit tumor growth in vivo. The tri-specific killer engager (TriKETM) was assembled by DNA shuffling and ligation using DNA encoding a camelid anti-CD16 antibody fragment, a wild-type IL-15 moiety, and an anti-B7-H3 scFv (clone 376.96). The expressed and purified cam1615B7H3 protein was tested for in vitro NK cell activity against a variety of tumors and in vivo against a tagged human MA-148 ovarian cancer cell line grafted in NSG mice. cam1615B7H3 showed specific NK cell expansion, high killing activity across a range of B7-H3+ carcinomas, and the ability to mediate growth inhibition of aggressive ovarian cancer in vivo. cam1615B7H3 TriKE improves NK cell function, expansion, targeted cytotoxicity against various types of B7-H3-positive human cancer cell lines, and delivers an anti-cancer effect in vivo in a solid tumor setting.
Chronic lymphocytic leukemia (CLL) is characterized by chronic clonal expansion of mature CD19-expressing B lymphocytes and global dysfunction of immune effectors, including natural killer (NK) cells. CLL remains incurable, and novel approaches to refractory CLL are needed. Our group has previously described trispecific killer engager (TriKE) molecules that redirect NK cell function against tumor cells. TriKE reagents simultaneously bind an activating receptor on NK cells, CD16, and a tumor antigen while also providing an NK cell expansion signal via an interleukin-15 moiety. Here we developed the novel CD19-targeting 161519 TriKE. We demonstrate that 161519 TriKE induced killing of a CD19-expressing Burkitt’s lymphoma cell line and examined the impact on primary CLL targets using healthy donor and patient NK cells. 161519 TriKE induced potent healthy donor NK cell activation, proliferation, and directed killing. Furthermore, 161519 TriKE rescued the inflammatory function of NK cells obtained from CLL patient peripheral blood samples. Finally, we show that 161519 TriKE induced better directed killing of CLL in vitro when compared with rituximab. In conclusion, 161519 TriKE drives a potent activating and proliferative signal on NK cells, resulting in enhanced NK cell expansion and CLL target killing. Our findings indicate the potential immunotherapeutic value of 161519 TriKE in CLL.
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