Session: 652. Myeloma: Pathophysiology and Pre-Clinical Studies, excluding Therapy: Poster II
Hematology Disease Topics & Pathways:
Diseases, multiple myeloma, Biological, antibodies, Therapies, Plasma Cell Disorders, immunotherapy, Lymphoid Malignancies, NK cells
We have developed an off-the-shelf NK cell immunotherapy derived from genetically engineered, induced pluripotent stem cells (iPSC) for enhanced ADCC in combination with daratumumab. iPSCs were engineered to express a high-affinity, non-cleavable CD16 construct (hnCD16) in combination with complete bi-allelic disruption of the CD38 gene (hnCD16 CD38-/-), and the engineered iPSCs were subsequently differentiated into NK (iNK) cells. We hypothesized that CD38-deficient iNK cells would exhibit improved survival by avoiding daratumumab-induced NK cell fratricide, while expression of the hnCD16 transgene would enhance ADCC against myeloma cells in combination with daratumumab.
Genetic modification was confirmed in hnCD16 CD38-/- iNK cells by flow cytometry, demonstrating abrogation of CD38 expression (Fig. 1A) and constitutive high expression of CD16 (Fig. 1B). Additionally, hnCD16 iNK cells and hnCD16 CD38-/- iNK cells expressed similar levels of SLAMF7/CD319 (the target of elotuzumab) and NKG2A (Fig. 1C and D). No significant difference in iNK cell differentiation, expansion, maturation, activation, or ability to mediate natural cytotoxicity was observed. In contrast to previous reports, we observed no effect of CD38-deficiency on CD16-mediated calcium flux between hnCD16 iNK cells and hnCD16 CD38-/- iNK cells (Figure 1E). In vitro culture of NK cells in the presence of daratumumab led to NK cell fratricide for both peripheral blood-derived NK cells and hnCD16 iNK cells (Fig. 1F). Daratumumab-induced NK cell fratricide was dependent upon expression of both CD16 and CD38, as unmodified iNK with low CD16 levels (~20% of cells) showed reduced cell death in the presence of daratumumab, which was entirely absent in hnCD16 CD38-/- iNK cells (Fig. 1F). This data was confirmed by extended culture of NK cells with RPMI-8226 tumor spheroids in the presence or absence of daratumumab. The number of hnCD16 iNK cells and peripheral blood NK cells were significantly reduced compared to hnCD16 CD38-/- iNK cells (p>0.005, Fig. 1 G). Importantly, hnCD16 CD38-/- iNK cells were better able to mediate ADCC towards MM1.S multiple myeloma cells compared to hnCD16 iNK cells (Fig. 1H).
Taken together, these data support our hypothesis that targeted knock out of CD38 on NK cells alleviates daratumumab-induced NK cell fratricide that occurs through the crosslinking of CD16 and CD38 on neighboring NK cells, leading to augmented anti-myeloma immunity. These data provide a translatable, proof of concept study demonstrating precision genetic engineering of iPSC to generate off-the-shelf NK cell immunotherapy to enhance daratumumab mediated ADCC in multiple myeloma. We propose a strategy of off-the-shelf hnCD16 CD38-/- iNK infusion in combination with daratumumab to overcome NK cell depletion effects of CD38 targeted agents and to improve myeloma patient outcomes.
Disclosures: Bjordahl: Fate Therapeutics Inc.: Employment. Cichocki: Fate Therapeutics Inc.: Consultancy, Research Funding. Gaidarova: Fate Therapeutics Inc: Employment. Pride: Fate Therapeutics Inc.: Employment. Kaufman: Fate Therapeutics: Consultancy, Research Funding. Malmberg: Fate Therapeutics Inc.: Consultancy, Research Funding. Valamehr: Fate Therapeutics Inc.: Employment. Miller: Fate Therapeutics: Consultancy, Patents & Royalties, Research Funding; GT Biopharma: Consultancy, Patents & Royalties, Research Funding; Dr. Reddy's Labratories: Other: SAB; Onkimmune: Other: SAB; CytoSen: Other: SAB.
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