Interleukin-15 augments NK cell-mediated ADCC of alemtuzumab in patients with CD52+ T-cell malignancies.

Interleukin-15 (IL-15) monotherapy substantially increases the number and activity of natural killer (NK) cells and CD8+ T cells but has not produced clinical responses. In a xenograft mouse model, IL-15 enhanced the NK cell-mediated antibody-dependent cell cytotoxicity (ADCC) of the anti-CD52 antibody alemtuzumab and led to significantly more durable responses than alemtuzumab alone. To evaluate whether IL-15 potentiates ADCC in humans, we conducted a phase 1 single-center study of recombinant human IL-15 and alemtuzumab in patients with CD52-positive mature T-cell malignances.

A very long-acting IL-15: implications for the immunotherapy of cancer.

Background: Interleukin-15 (IL-15) is an important cytokine necessary for proliferation and maintenance of natural killer (NK) and CD8 T cells, and with great promise as an immuno-oncology therapeutic. However, IL-15 has a very short half-life and a single administration does not provide the sustained exposure required for optimal stimulation of target immune cells. The purpose of this work was to develop a very long-acting prodrug that would maintain IL-15 within a narrow therapeutic window for long periods-similar to a continuous infusion.

Genome-wide CRISPR screen identifies CDK6 as a therapeutic target in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive T-cell malignancy with a poor prognosis with current therapy. Here we report genome-wide CRISPR-Cas9 screening of ATLL models, which identified CDK6, CCND2, BATF3, JUNB, STAT3, and IL10RB as genes that are essential for the proliferation and/or survival of ATLL cells. As a single agent, the CDK6 inhibitor palbociclib induced cell cycle arrest and apoptosis in ATLL models with wild-type TP53.

Effective Cytotoxicity of Dendritic Cells against Established T Cell Lymphomas in Mice.

T cell lymphomas arise in mice that constitutively express a single TCR in the absence of NK cells. Upon TCR engagement these lymphomas are able to corrupt tumor surveillance by decreasing NK cell numbers. In this study, we investigate the outcome of interactions between these T cell lymphomas and dendritic cells.

Short-course IL-15 given as a continuous infusion led to a massive expansion of effective NK cells: implications for combination therapy with antitumor antibodies.

Background: Full application of cytokines as oncoimmunotherapeutics requires identification of optimal regimens. Our initial effort with intravenous bolus recombinant human interleukin-15 (rhIL-15) was limited by postinfusional reactions. Subcutaneous injection and continuous intravenous infusion for 10 days (CIV-10) provided rhIL-15 with less toxicity with CIV-10 giving the best increases in CD8 lymphocytes and natural killer (NK) cells.

Engagement of lymphoma T cell receptors causes accelerated growth and the secretion of an NK cell-inhibitory factor.

The development of T cell lymphomas in mice that constitutively express a single T cell receptor is surveilled by the action of NK cells. We investigated the effects of engaging the lymphoma TCR in this mouse model. We stimulated lymphoma cells expressing an ovalbumin-specific TCR in vivo using listeria monocytogenes as a vehicle.

IL-15 in the Combination Immunotherapy of Cancer.

We completed clinical trials of rhIL-15 by bolus, subcutaneous, and continuous intravenous infusions (CIV). IL-15 administered by CIV at 2 mcg/kg/day yielded a 38-fold increase in 10- day number of circulating NK cells, a 358-fold increase in CD56 NK cells and a 5.8-fold increase in CD8 T cells.

NK cells prevent T cell lymphoma development in T cell receptor-transgenic mice.

Mice that express a single transgenic T cell receptor have a low incidence of T cell lymphoma development. We investigated whether this tumor development is restricted by surveillance mechanisms that are exerted by IL-15-dependent cells. Lymphoma incidence was increased to between 30 and 60% when TCR transgenes were expressed in IL-15-deficient mice.

IL15 by Continuous Intravenous Infusion to Adult Patients with Solid Tumors in a Phase I Trial Induced Dramatic NK-Cell Subset Expansion.

Purpose: The first-in-human clinical trial with human bolus intravenous infusion IL15 (rhIL15) was limited by treatment-associated toxicity. Here, we report toxicity, immunomodulation, and clinical activity of rhIL15 administered as a 10-day continuous intravenous infusion (CIV) to patients with cancers in a phase I trial.

Patients And Methods: Patients received treatment for 10 days with CIV rhIL15 in doses of 0.

IL-15 enhanced antibody-dependent cellular cytotoxicity mediated by NK cells and macrophages.

The goal of cancer immunotherapy is to stimulate the host immune system to attack malignant cells. Antibody-dependent cellular cytotoxicity (ADCC) is a pivotal mechanism of antitumor action of clinically employed antitumor antibodies. IL-15 administered to patients with metastatic malignancy by continuous i.

IL-2 and IL-15 blockade by BNZ-1, an inhibitor of selective γ-chain cytokines, decreases leukemic T-cell viability.

Interleukin-15 (IL-15) and IL-2 drive T-cell malignancies including T-cell large granular lymphocyte leukemia (T-LGLL) and HTLV-1 driven adult T-cell leukemia (ATL). Both cytokines share common γ-chain receptors and downstream signaling pathways. T-LGLL is characterized by clonal expansion of cytotoxic T cells and is associated with abnormal JAK/STAT signaling.

Targeting the HTLV-I-Regulated BATF3/IRF4 Transcriptional Network in Adult T Cell Leukemia/Lymphoma.

Adult T cell leukemia/lymphoma (ATLL) is a frequently incurable disease associated with the human lymphotropic virus type I (HTLV-I). RNAi screening of ATLL lines revealed that their proliferation depends on BATF3 and IRF4, which cooperatively drive ATLL-specific gene expression. HBZ, the only HTLV-I encoded transcription factor that is expressed in all ATLL cases, binds to an ATLL-specific BATF3 super-enhancer and thereby regulates the expression of BATF3 and its downstream targets, including MYC.

IL15 Infusion of Cancer Patients Expands the Subpopulation of Cytotoxic CD56 NK Cells and Increases NK-Cell Cytokine Release Capabilities.

The cytokine IL15 is required for survival and activation of natural killer (NK) cells as well as expansion of NK-cell populations. Here, we compare the effects of continuous IL15 infusions on NK-cell subpopulations in cancer patients. Infusions affected the CD56 NK-cell subpopulation in that the expansion rates exceeded those of CD56 NK-cell populations with a 350-fold increase in their total cell numbers compared with 20-fold expansion for the CD56 subset.

Redistribution, hyperproliferation, activation of natural killer cells and CD8 T cells, and cytokine production during first-in-human clinical trial of recombinant human interleukin-15 in patients with cancer.

Purpose: Interleukin-15 (IL-15) has significant potential in cancer immunotherapy as an activator of antitumor CD8 T and natural killer (NK) cells. The primary objectives of this trial were to determine safety, adverse event profile, dose-limiting toxicity, and maximum-tolerated dose of recombinant human IL-15 (rhIL-15) administered as a daily intravenous bolus infusion for 12 consecutive days in patients with metastatic malignancy.

Patients And Methods: We performed a first in-human trial of Escherichia coli-produced rhIL-15.

Loss of cytotoxicity and gain of cytokine production in murine tumor-activated NK cells.

NK cells are able to form a functional memory suggesting that some NK cells are surviving the activation process. We hypothesized that NK cell activation causes the development of a distinct NK cell subset and studied the fate of murine post-activation NK cells. Activation was achieved by in vivo and in vitro exposures to the melanoma tumor cell line B16 that was followed by differentiation in IL-2.

Paracrine and transpresentation functions of IL-15 are mediated by diverse splice versions of IL-15Rα in human monocytes and dendritic cells.

Background: IL-15 can either be transpresented by IL-15Rα or be secreted.

Results: New N- and C-terminal splice versions of human IL-15Rα determine whether IL-15 is secreted or stays bound to the cell membrane.

Conclusion: IL-15Rα isoforms determine the mode of action of IL-15.

Selective dependence of H2-M3-restricted CD8 responses on IL-15.

We studied whether CD8 T cell responses that are mediated by unconventional MHC class Ib molecules are IL-15 dependent in mice. CD8(+) T cell responses to Listeria monocytogenes infection that are restricted by the MHC class Ib molecule H2-M3 decreased in the absence of IL-15, whereas other primary MHC class Ib- and MHC class Ia-restricted responses were IL-15 independent. This result was confirmed in MHC class Ia-deficient mice in which IL-15 deficiency also reduced H2-M3-restricted but not all CD8 T cell responses to L.

Interleukin-15 combined with an anti-CD40 antibody provides enhanced therapeutic efficacy for murine models of colon cancer.

IL-15 has potential as an immunotherapeutic agent for cancer treatment because it is a critical factor for the proliferation and activation of natural killer (NK) and CD8(+) T cells. Administration of anti-CD40 antibodies has shown anti-tumor effects in vivo through a variety of mechanisms. Furthermore, activation of CD40 led to increased expression of IL-15 receptor-alpha by dendritic cells, an action that is critical for trans-presentation of IL-15 to NK and CD8(+) T cells.

Preassociation of IL-15 with IL-15R alpha-IgG1-Fc enhances its activity on proliferation of NK and CD8+/CD44high T cells and its antitumor action.

In the induction of an immune response, IL-15Ralpha on APCs transpresents IL-15 to NK and CD8(+)/CD44(high) T cells that express the IL-2/15Rbeta and gammac subunits only. In this study, we show data mimicking this transpresentation by using IL-15 preassociated with a chimeric protein that is comprised of the extracellular domain of murine IL-15Ralpha and the Fc portion of human IgG1. When tested in vitro, IL-15Ralpha-IgG1-Fc strongly increased the IL-15-mediated proliferation of murine NK and CD8(+)/CD44(high) T cells.

ITK and IL-15 support two distinct subsets of CD8+ T cells.

CD8(+) T cells are commonly divided into naïve CD44(lo)CD122(lo) and "memory phenotype" CD44(hi)CD122(hi) cells. Here we show data suggesting that these two cell populations represent independent CD8(+) T cell subsets. Whereas IL-15(-/-) mice lack CD44(hi)CD122(hi) CD8(+) T cells, mice deficient in the kinase ITK lack CD44(lo)CD122(lo) cells among CD8(+) T cells.

Survival adjustment of mature dendritic cells by IL-15.

The survival of CD8+/CD44(hi) memory phenotype T cells depends on an IL-15 activity on nonlymphoid cells. Here, we report that IL-15 and its receptor were induced on dendritic cells (DCs) by a combination of IFN-gamma and NF-kappaB relA inducers. IL-15 conferred in an autocrine loop resistance to apoptosis that accompanied the maturation process in DCs in vitro.

Role of trans-cellular IL-15 presentation in the activation of NK cell-mediated killing, which leads to enhanced tumor immunosurveillance.

Interleukin 15 (IL-15) is a critical factor for the proliferation and activation of natural killer (NK) and CD8 T cells. Recently, we demonstrated that IL-15Ralpha expressed on monocytes/dendritic cells captures and presents IL-15 to neighboring cells in trans (trans-presentation of IL-15) through cell-cell contact. In the current study, we provide evidence that the IL-15 presented in trans, but not soluble IL-15 at physiologic concentrations, augments the killing activity mediated by NK cells in vitro.

Distinct pathways involving the FK506-binding proteins 12 and 12.6 underlie IL-2-versus IL-15-mediated proliferation of T cells.

The molecular basis for the different roles of IL-2 and IL-15 in lymphocyte function has been poorly defined. Searching for differences that underlie the distinct T cell responses to the two cytokines, we observed a marked susceptibility of the IL-15-induced but not of the IL-2-induced proliferation to rapamycin despite a decrease of p70S6 kinase (p70S6K) activation by the drug in response to both cytokines. Activated splenic T lymphocytes deficient in the FK506-binding protein (FKBP) 12, a target of rapamycin activity, had reduced proliferation in response to IL-15 but not to IL-2.

IL-15Ralpha recycles and presents IL-15 In trans to neighboring cells.

We report intriguing aspects of the contribution of IL-15Ralpha to IL-15 functions. Consistent with high-affinity interactions between IL-15 and IL-15Ralpha, these two molecules form stable complexes on the cell surface of activated monocytes. The formation of IL-15/IL-15Ralpha complexes on cell surfaces induces a trans-endosomal recycling of IL-15 leading to the persistence of surface-bound IL-15 due to the constant reappearance of IL-15 on plasma membranes.