Locally Targeted Off-The-Shelf NK Cells For Ovarian Cance

In 2010 we treated our first patient with advanced ovarian cancer (OC) with intravenous (IV) allogeneic NK cells. Since then, we have worked to improve the persistence and function of NK cells in this disease. Based on our pre-clinical findings, we designed and completed a clinical trial testing the safety and efficacy of ex vivo expanded (IL-15 + GSK3b inhibitor) adaptive NK cells administered intraperitoneally (IP) to treat OC. These allogeneic NK cells persisted and had enhanced in vivo function for up to 21 days with promising clinical responses. These initial results support improved NK cell persistence with IP versus IV delivery and NK cell-mediated antitumor effects in advanced OC. The overarching hypothesis for Project 3 is that IP delivery of NK cells will be optimal for clinical testing of NK cells gene modified to target OC through their Fc receptors. We will test an off-the-shelf NK cell product that resists CD16 cleavage (hnCD16) in combination with IL-2 and an Fc-optimized mAb against B7-H3, a target highly expressed on OC. We predict this NK product will overcome suppressive mechanisms and mediate potent anti-tumor activity and that targeting these cells with specific killer immune engagers containing IL-15 will enhance their specificity to kill OC. These studies are supported by strong pre-clinical data showing high NK cell frequencies with markedly diminished CD16 expression in ascites from OC patients. The induced pluripotent stem cell (iPSC)-derived NK (iNK) cell product (FT516) proposed for use in this project has non-cleavable CD16 to sustain antibody-dependent cellular cytotoxicity (ADCC) when combined with an Fc optimized anti-B7-H3 antibody. To further enhance the antitumor efficacy of FT516 NK cells, we will test our own IL-15-containing Trispecific Killer Engagers: 1) a 1615B7H3 TriKE comprised of three functional domains: a) an NK cell-engaging single domain Ab fragment against CD16, b) an OC-engaging Ab fragment against B7-H3, and c) an IL-15 linker between them; 2) a 1615CD133 TriKE to target OC stem cells; and 3) a 1615CD133B7H3 TriKE for dual targeting of OC cells. Lastly, supported by strong pre-clinical data, we developed a CD64/CD16 chimeric receptor, as CD64 is the only high-affinity receptor that can stably bind monomeric IgG with >30-fold higher affinity than CD16. This novel receptor has been genetically edited into iPSC-derived NK cells and will be tested in vitro and in xenogeneic mouse models of OC. We have developed Specific Aims to 1) clinically test whether IP delivery of FT516 iNK cells combined with enoblituzumab (anti B7-H3 antibody) will enhance efficacy through ADCC in advanced OC; 2) pre-clinically test whether single- or dual-targeted TriKEs will enhance the antitumor efficacy of FT516 NK cells; and 3) pre-clinically test whether multi-antibody targeting by iNK cells expressing the chimeric CD64/16A receptor will enhance function. The themes developed in Project 3 will inform the Program on whether delivery of an off-the-shelf NK cell product directly into the peritoneal cavity, an environment that may evade immune attack, can enhance tumor control. Results from these studies will inform Projects 1 and 2 on the mechanisms of rejection versus the intrinsic capacity of NK cells to persist in vivo.