Advances in adoptive transfer immunotherapy have found beneficial effects for Interleukin-15 (IL-15) in the graft versus tumor (GvT) activity of NK and cytotoxic T cells. However, the benefits of this activity must be weighed against the increased risk of acute graft versus host disease (GvHD) in patients. We propose that BNZ-2, a peptide antagonist of IL-15 and IL-21 signaling, as a therapeutic option for GvHD that may relieve intestinal pathologies while retaining adoptive transfer activity. As a novel model of intestinal inflammatory disease, we have found that humanization with peripheral blood mononuclear cells (PBMCs) of NOG mice with transgenic expression of human IL-15 (NOG-IL15) consistently catalyzes the onset of intestinal GvHD within twenty days of engraftment. To investigate whether BNZ-2 can inhibit IL-15-catalized intestinal GvHD we treated NOG-IL15 mice and assessed the degree of intestinal GvHD and the immunophenotype of engrafted cells following twenty days of humanization with four million unmanipulated PBMCs. BNZ-2 treatment inhibited with equal efficacy to anti-IL-15 the localization of immune cells to the intestinal lamina propria protecting the tissue from inflammation-induced loss of tissue integrity. However, BNZ-2 treatment retained the systemic engraftment of the blood and spleen, including NK and CD8 cytotoxic T-cells. These data support BNZ-2 as a therapeutic candidate for GvHD treatment, describe a new model of intestinal GvHD, and suggest that a therapeutic window exists that separates intestinal GvHD pathologies from the benefits of adoptive cell transfer.

Citation Format: Kevin R. Kipp, Nick Doerr, Laith Q. Al-Mawsawi, Woo Jae Kim, Adrian J. Giovannone, Nazli Azimi. BNZ-2, a dual specific IL15/IL21 inhibitor, rescues humanized NOG-IL15 transgenic mice from intestinal acute graft versus host disease without disrupting NK and CD8 T cell engraftment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB143.