TBK1/IKKε-IN-5

TBK1/IKKε-IN-5(compound 1) effectively blocks immune suppressive cytokine elaboration by CT26 cell line spheroids, without cytotoxic effects, and enhances secretion of IL-2 and IFN-γ from purified CD4+ and CD8+ T cells from healthy human donors and IL-2 from Jurkat human T-cell leukemia cells. Ex vivo addition of TBK1/IKKε-IN-1(compound 1) to PD-1 blockade enhances killing of CT26 MDOTS, associated with decreased levels of CCL4, CCL3, and IL-1β and induction of cytokines involved in activated innate immune responses.^[1]

Interleukin-2 and interferon gamma analysis—Freshly isolated human CD4+ and CD8+ T cells are spun down and resuspended in serum free X-vivo15 media supplemented with 5 ng/mL IL-17 and incubated overnight at 37°C. Cells are plated on anti-CD3 coated plates with 2 μg/mL anti-CD28. Cells are treated in replicate plates with a dose-titration of TBK1/IKKε-IN-1(compound 1) for 24 hours for IL-2 and 96 hours for IFNγ. IL-2 and IFNγ in the supernatant are measured using single-or multi-plex immunoassay. Jurkat T cell leukemia cells plated on anti-CD3 coated plates are treated with a dose titration of TBK1/IKKε-IN-1(compound 1) for 24 hours.

Balb/c mice bearing CT26 tumors are treated with TBK1/IKKε-IN-1(compound 1) ± anti-PD-L1. Consistent with MDOTS profiling data, greater tumor control and longer survival is evident with TBK1/IKKε-IN-1(compound 1) + anti-PD-L1 than with either TBK1/IKKε-IN-1(compound 1) or anti-PD-L1 alone. Reimplantation of CT26 into mice with exceptional responses to combination therapy shows no growth, whereas EMT-6 implanted tumors grow normally, suggesting induction of immunologic memory of CT26 cells in mice treated with TBK1/IKKε-IN-1(compound 1) + anti-PD-L1. Therefore, MDOTS profiling effectively recapitulates the in vivo response to PD-1 blockade +/− TBK1/IKKε inhibition, highlighting the potential of ex vivo screening in MDOTS to develop combination immunotherapies.^[1]