Combination of cancer vaccine with CD122-biased IL-2/anti-IL-2 Ab complex shapes the stem-like effector NK and CD8+ T cells against tumor

Abstract

Background: A key to success of cancer immunotherapy is the amplification and sustenance of various effector cells. The hallmark of prominent antitumor T cells is their long-term effector function. Although interleukin (IL)-2 is an attractive cytokine, several attempts have been made towards developing IL-2 modalities with improved effectiveness and safety that enhance natural killer (NK) cells or T cells in cancer models. However, whether such IL-2 modalities can simultaneously support long-term innate and adaptive immunity, particularly stem-like memory, has not been shown. To resolve this issue, we compared the antitumor cellular mechanism with two IL-2/anti-IL-2 complexes (IL-2Cxs) administered in combination with a therapeutic cancer vaccine, which we had previously established as an in vivo dendritic cell-targeting therapy.

Methods: Two types of IL-2Cxs, CD25-biased IL-2Cx and CD122-biased IL-2Cx, together with a Wilms' tumor 1-expressing vaccine, were evaluated in a leukemic model. The immunological response and synergistic antitumor efficacy of these IL-2Cxs were then evaluated.

Results: When CD25-biased or CD122-biased IL-2Cxs in combination with the vaccine were assessed in an advanced-leukemia model, the CD122-biased IL-2Cx combination showed 100% survival, but the CD25-biased IL-2Cx did not. We first showed that invariant natural killer T (NKT) 1 cells are predominantly activated by CD122-biased IL-2Cx. In addition, in-depth analysis of immune responses by CD122-biased IL-2Cx in lymphoid tissues and the tumor microenvironment revealed a dramatic increase in the distinct subsets of NK and CD8⁺ T cells with stem-like phenotype (CD27⁺Sca-1^hi, CXCR3^hi, CD127⁺TCF-1⁺T-bet⁺ Eomes⁺). Moreover, CD122-biased IL-2Cx combination therapy maintained long-term memory CD8⁺ T cells capable of potent antitumor protection. After the high dimensional profiling analysis of NK and CD8⁺T cells, principal component analysis revealed that the stem-like-NK cell and stem-like-CD8⁺T cell state in the combination were integrated in the same group.

Conclusions: CD122-biased IL-2Cx combined with the vaccine can induce a series of reactions in the immune cascade, including activation of not only NKT1 cells, but also NK and CD8⁺ T cells with a stem-like memory phenotype. Since it can also lead to a long-term, strong antitumor response, the combination of CD122-biased IL-2Cx with a vaccine may serve as a potential and competent strategy for patients with advanced cancer.

Keywords: CD8-Positive T-Lymphocytes; Cytokines; Immunologic Memory; Killer Cells, Natural; Natural Killer T-Cells.