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1077 Development of a molecular targeted cytokine that specifically expands Vgamma9Vdelta2 T cells and potentiates anti-tumor activity
  1. Bryan Becklund,
  2. Kaitlyn Robinson,
  3. Kyle Jones,
  4. Angelica Sanabria,
  5. Elisebeth Torretti,
  6. Andrew Eckles,
  7. Abrahim Hussain,
  8. Sae Jeong Ahn,
  9. Rajay Pandit,
  10. Florian Sulzmaier,
  11. John Timmer and
  12. Brendan Eckelman
  1. Inhibrx, La Jolla, CA, USA


Background Vgamma9Vdelta2 (Vg9Vd2) T cells are an ideal target for cancer immunotherapy due to their ability to recognize stress-related ligands from transformed cells and eliminate them with broad, potent cytotoxicity.1 One limitation restraining the ability of Vg9Vd2 T cells from eliminating tumors is that they are a rare population in peripheral blood. Efforts to expand Vg9Vd2 T cells in vivo have typically relied on treatment with bisphosphonates and low-dose interleukin-2 (IL-2). This combination is limited by rapid clearance of the molecules, competition for IL-2 and dose-limiting toxicities.2 Using our molecular targeted cytokine (MTC) platform, we developed an alternative strategy to specifically expand Vg9Vd2 T cells utilizing a detuned IL-2 variant targeted to the Vg9Vd2 T cell receptor.

Methods Human IL-2 was engineered to eliminate CD25 binding and have reduced affinity for CD122.3 A high-affinity single-domain antibody specific to the Vg9-subunit of the Vg9Vd2 T cell receptor targets this cytokine to cells expressing the target antigen and thereby restricts IL-2 activity to Vg9Vd2 T cells. The ability of this Vg9Vd2-targeted MTC (anti-Vg9xIL2-X) to selectively bind and activate Vg9Vd2 T cells was assessed in vitro utilizing human PBMCs from healthy donors and dissociated tumor cells (DTCs) from various indications. IL-2 signaling and cell proliferation were analyzed by flow cytometry. Cancer-specific target cell killing was determined by coculturing Vg9Vd2 T cells with labeled tumor cells or healthy B cells. Expansion of Vg9Vd2 T cells in vivo was analyzed in NSG-B2M KO mice engrafted with human PMBCs.

Results Anti-Vg9xIL2-X bound Vg9Vd2 T cells and activated STAT5 signaling in a target-dependent manner. Treatment with anti-Vg9xIL2-X led to a dramatic increase in proliferation and accumulation of Vg9Vd2 T cells in healthy human PBMCs and DTCs. Anti-Vg9xIL2-X-driven expansion of Vg9Vd2 T cells increased expression of cytotoxic effector molecules, including IFNg and granzyme-B, leading to potent in vitro anti-tumor activity across numerous cancer cell types. The killing activity was selective for transformed cells as healthy cells were largely spared. Treatment with anti-Vg9xIL2-X also improved antibody dependent target cell killing by Vg9Vd2 T cells. Finally, dosing of human PBMC-engrafted mice with anti-Vg9xIL2-X was well-tolerated and resulted in an increased prevalence and specific expansion of Vg9Vd2 T cells.

Conclusions Utilizing our MTC platform, we have developed a targeted cytokine that specifically activates and expands Vg9Vd2 T cells. By restraining IL-2 activity to this subset, we hope to limit IL-2-mediated toxicity and enhance Vg9Vd2 T cell anti-tumor activity across numerous cancer types.


  1. Yazdanifar M, Barbarito G, Bertaina A, Airoldi I. γδ T Cells: The Ideal Tool for Cancer Immunotherapy. Cells. 2020;9:1305.

  2. Hoeres T, Smetak M, Pretscher D, Wilhelm M. Improving the Efficiency of Vγ9Vδ2 T-Cell Immunotherapy in Cancer. Front Immunol 2018;9:800.

  3. Sulzmaier F, Kinkead H, Polovina A, Kern N, Sanabria A, Macedo C, et al. 722 INBRX-121 is an NKp46-targeted detuned IL-2 with antitumor activity as a monotherapy or in combination with multiple cancer immunotherapy modalities. J Immunother Cancer. 2021;9:A751–A751.

Ethics Approval All animal studies were conducted in accordance with AAALAC regulations and were approved by the IACUC for Explora BioLabs (#SP17-010-013).

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