Heterodimeric IL-15 in Cancer Immunotherapy

Division Of Basic Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

We explored the biology of IL-15 and showed that efficient production of IL-15 is possible only by co-expression in the same cell with the so-called IL-15 Receptor-alpha. We have shown that IL-15 injection accelerates the recovery of lymphocytes in mice rendered lymphopenic after treatment with cytotoxic drugs. We also showed that hetIL-15 can replace the need for lymphodepletion in Adoptive Cell Transfer (ACT), since the transferred cells can survive, proliferate and enter the tumors after hetIL-15 treatment. This may have important clinical implications for ACT protocols. We have used the previously developed technologies of RNA optimization to optimize expression of IL-15 cytokine, and have shown that we can over-produce bioactive cytokine after DNA delivery in mice and macaques. DNA delivery of vectors expressing heterodimeric IL-15 leads to systemically active levels of cytokine and the increased proliferation of NK and T cells. We have shown that hetIL-15 greatly increases lymphocyte infiltration in several tumors in mouse models and in macaques, suggesting a general method to increase lymphocyte infiltration, which is associated with anti-tumor activity. On the basis of these results, we have developed first-in-human clinical trials of hetIL-15 in metastatic cancers and also in combination with anti-PD-1 check point inhibitor (NCT02452268; collaboration with Novartis). In addition to cancer immunotherapy, IL-15 has generated strong interest for clinical use to treat HIV infection, especially in protocols targeting viral eradication or a functional cure. The use of IL-15 as an immune therapeutic agent against HIV infection is based on its effects as a growth factor and key regulator of cytotoxic responses mediated by both the innate (NK cells) and the adaptive (CTL) arms of the immune system. Using hetIL-15 treatment in the RM model for HIV infection, we have demonstrated that: (i) a regimen with increasing dosing (step-dose) of hetIL-15 is well tolerated by different routes of delivery and increases T lymphocytes (CD8, CD4 and gamma/delta) and NK cells with high granzyme content in peripheral blood, mucosal sites and LN. (ii) Importantly, hetIL-15 treatment promotes the entrance of cytotoxic (GrzB+) CD8+ T cells in the B cell follicles, areas within the LN where CTL are typically excluded and where SIV/HIV infected follicular helper CD4+ T cells reside. hetIL-15 treatment led to significant decrease in cell-associated viral RNA within the LN as well as in plasma viremia in SHIV infected macaques. (iii) We also showed that hetIL-15 can enhance ADCC in LN, which provides an additional mechanism of elimination of infected cells. We have shown that hetIL-15 is incorporated in exosomes and have produced sufficient quantities for animal experiments. Extensive transcriptomics and proteomics analysis has revealed additional pathways affected by hetIL-15 pharmacologically. Of note, we have studied the effects of hetIL-15 in the number and properties of Dendritic Cells (DC) in tumors. We have demonstrated that DC in tumors increase upon hetIL-15 treatment. DC participate in a network of cells that are induced during hetIL-15 treatment and in turn support more recruitment of effector cells in tumor sites. In experiments that show the importance of IL-15 on the development of immune response, we identified a systemic signature in blood of cytokines induced transiently after vaccination by the Pfizer mRNA vaccine. This signature includes increases in IL-15, IFN-gamma, and IP-10/CXCL10 after the 1st vaccination, which were enriched by tumor necrosis factor alpha (TNF-alpha) and IL-6 after the 2nd vaccination. In previously COVID-19-infected individuals, a single vaccination resulted in both strong cytokine induction and antibody titers similar to the ones observed upon booster vaccination in antigen-naive individuals, a result with potential implication for future public health recommendations. In an additional line of research, we have shown in collaborative work with colleagues in Oregon, Seattle and Uppsala that IL-15 transcriptional signature predicts protection by another viral vaccine: The differential IL-15 gene set response to RhCMV/SIV vaccine strongly correlated with the pre-vaccination activity of this pathway, with reduced baseline expression of IL-15 response genes significantly correlating with higher vaccine-induced IL-15 signaling and subsequent vaccine protection, suggesting that a robust de novo vaccine-induced IL-15 signaling response is needed to program vaccine efficacy. The RhCMV/SIV vaccine imparts a coordinated and persistent induction of innate and adaptive immune pathways featuring IL-15, a known regulator of CD8+ T cell function, that support the ability of vaccine-elicited unconventionally restricted CD8+ T cells to mediate protection against SIV challenge. We have used optimal therapeutic vaccination, and a combination of therapeutic interventions in macaque model of chronic controlled SIN infection under Antiretroviral therapy. We used our candidate immunotherapy drug hetIL-15 in combinations with anti-PD-1, broadly neutralizing Antibodies against SIV, or therapeutic vaccination. Our results provide for the first time the exciting possibility that optimal treatment protocols can decrease virus reservoir as measured in blood and lymph nodes. The analysis of a 56-macaque study is finalized and this should be used as proof-of-concept for human clinical studies. We have continued to work on mouse models of cancer to examine mode of action of our candidate immunotherapy drug, hetIL-15. Triple-negative breast cancer (TNBC) is considered the most aggressive and difficult to treat breast cancer type. We have tested hetIL-15 in combination with chemotherapy and surgical removal of the primary tumor and evaluated the anti-metastatic potential of these combinations in mice bearing orthotropic TNBC tumors. We showed that hetIL-15 exhibits its anti-metastatic activity by both diminishing circulating tumor cells (CTCs) shed by the primary tumor and by suppressing local metastasis formation in the lungs. Co-administration with doxorubicin enhances the anti-metastatic effect and skews the immune landscape towards an effector over immunosuppressive phenotype. Our findings further show that hetIL-15, alone or in combination with Doxorubicin, eliminates metastases in lungs of tumor resected mice leading not only to cures but also to immunological memory against the primary tumor. Thus, these chemo-immunotherapeutic combinations may be important for improving current therapeutic approaches against TNBC. We have also explored locoregional administration of hetIL-15 in an orthotopic TNBC mouse models. Optimal monotherapy treatment by hetIL-15 resulted in tumor eradication in 40% of treated mice, reduction of metastasis and induction of immunological memory against breast cancer cells. hetIL-15 re-shaped the tumor microenvironment by promoting the intratumoral accumulation of cytotoxic lymphocytes, conventional type 1 dendritic cells (cDC1s) and a novel DC population expressing both CD11b and CD103 markers. These CD103intCD11b+DCs share phenotypic and gene expression characteristics with both cDC1s and cDC2s, have transcriptomic profiles similar to monocyte-derived DCs (moDCs) and correlate with tumor regression. Therefore, hetIL-15, a cytokine directly affecting lymphocytes and inducing cytotoxic cells, has also an indirect rapid and significant effect on the recruitment of myeloid cells, initiating a cascade for tu *TRUNCATED*