Immunotherapeutic Development of a Tri-Specific NK Cell Engager Recognizing BCMA

Chemotherapy-refractive multiple myeloma (MM) is serious and life-threatening, and better treatments are urgently needed. BCMA is a prominent marker on the cell surface of MM cells, rendering it an accepted target for antibody therapy. Considering that MM is a liquid tumor and immunotherapy has enjoyed success against leukemia, we devise an approach designed to enhance NK cell activity against MM. Ordinarily, NK cells function to naturally survey the body and eliminate malignant cells. Our platform approach is designed to enhance NK function. A tri-specific immune-engaging TriKE is manufactured, consisting of a camelid nanobody VHH antibody fragment recognizing CD16 expressed on NK cells and an scFv antibody fragment specifically recognizing BCMA. These two fragments are crosslinked by the human cytokine interleukin-15 (IL-15) known to have prominent activating effects on NK cells. The molecule, when tested by flow cytometry, shows activation of NK cells in their numbers and activity. Additionally, the molecule demonstrates anti-cancer effects in an in vivo xenograft model of human MM. We believe that the drug will have the capability of enhancing NK cells at the site of the immune synapse, i.e., the effector:target cell interface, and this will promote cancer remissions

NK-Cell-Mediated Targeting of Various Solid Tumors Using a B7-H3 Tri-Specific Killer Engager In Vitro and In Vivo

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

Harnessing features of adaptive NK cells to generate iPSC-derived NK cells for enhanced immunotherapy

Select subsets of immune effector cells have the greatest propensity to mediate antitumor responses. However, procuring these subsets is challenging, and cell-based immunotherapy is hampered by limited effector-cell persistence and lack of on-demand availability. To address these limitations, we generated a triple-gene-edited induced pluripotent stem cell (iPSC). The clonal iPSC line was engineered to express a high affinity, non-cleavable version of the Fc receptor CD16a and a membrane-bound interleukin (IL)-15/IL-15R fusion protein. The third edit was a knockout of the ecto-enzyme CD38, which hydrolyzes NAD+. Natural killer (NK) cells derived from these uniformly engineered iPSCs, termed iADAPT, displayed metabolic features and gene expression profiles mirroring those of cytomegalovirus-induced adaptive NK cells. iADAPT NK cells persisted in vivo in the absence of exogenous cytokine and elicited superior antitumor activity. Our findings suggest that unique subsets of the immune system can be modeled through iPSC technology for effective treatment of patients with advanced cancer