One major focus of the Waldmann Laboratory is the definition of the roles played by the IL-2/IL-2R and IL-15/IL-15R systems in the life and death of T-cells and the use of these insights to both develop IL-15 as a vaccine component and as a therapeutic agent to augment immune responses for the treatment of metastatic malignancies, as well as with the opposite goal to develop therapies directed toward inhibiting the IL-15/IL-15R signaling system for the treatment of adult T-cell leukemia and autoimmune diseases where disorders of the IL-15 system have been implicated in the disease generation and maintenance. IL-15 has a potential as an immunotherapeutic agent for cancer treatment because it is a critical factor that is involved in the generation and activation of NK and CD8 T-cells. The IL-15 receptor is a heterotrimeric receptor that includes IL-2/IL-15R beta (CD122) and the common gamma chain (CD132) shared with IL-2 and a private IL-15 specific IL-15R alpha subunit. Normally IL-15 is not secreted but acts as part of an immunological synapse. IL-15R alpha on dendritic cells presents IL-15 to IL-2/IL-15R beta and common gamma chain expressing NK and CD8 T-cells. Waldmann oversaw the Biopharmaceutical Development Program (BDP) NCI production of IL-15 and evaluated rhIL-15 in terms of safety (toxicity) pharmacokinetics, immunogenicity, autoimmunity and impact on elements of the normal immune system of rhesus macaques. When IL-15 was administered by continuous intravenous infusions (c.i.v.) at 20 micrograms/kg/ day for 10 days there was a six-fold increase in the number of circulating NK cells and an eighty-fold increase in the number of circulating effector memory CD8 T-cells. Following FDA and IRB approval a phase I clinical trial was completed that evaluated intravenous bolus infusions of recombinant IL-15 in adult humans with refractory malignant melanoma and metastatic renal cell cancer. Although IL-15 may be efficacious, IL-15 monotherapy in patients with malignancy is not optimal because of the limited expression of IL-15R alpha the required private receptor for IL-15. In addressing this impediment to the use of IL-15, the Waldmann Laboratory demonstrated that greater CD8 T-cell mediated therapeutic efficacy compared to IL-15 alone was achieved in a synergistic established murine TRAMP C2 prostate tumor model when a combination regimen was utilized that included a murine IL-15 administered in concert with an agonistic anti-CD40 antibody that augmented IL-15R alpha expression on dendritic cells. Using IL-15R alpha knockout mice and dendritic cells from such mice we demonstrated that the augmentation of IL-15R alpha expression induced by the anti-CD40 monoclonal antibody was required for the synergic efficacy of this combination. In addition, in independent studies we demonstrated that the simultaneous inhibition of two regulatory T-cell subset checkpoints by anti-PD1 and anti-CTLA4 enhanced IL-15 efficacy in a murine prostate tumor model. The above studies are directed toward the administration of IL-15 to augment immune responses in the treatment of malignancy. The Waldmann Laboratory also has a major program with the opposite goal of diminishing the action of gamma cytokines including IL-15 in situations where disorders of these cytokines play a pathogenic role in autoimmune diseases and T-cell malignancies. A major focus of these studies was on human T-cell lymphotropic virus 1 (HTLV-1) associated ATL, a major disease component of the Metabolism Branch?s Center of Excellence in lymphoid malignancies. We demonstrated that peripheral blood mononuclear cells (PBMCs) from patients with smoldering and chronic ATL spontaneously proliferated ex vivo in a gamma-c cytokine-dependent manner. In particular, HTLV-1 encoded Tax was shown to induce two autocrine (IL-2/IL-2R, IL-15/IL-15R) and one paracrine (IL-9/IL-9R) stimulatory loop that in turn activated the JAK1 (Janus kinase-1)-JAK3-STAT5 (signal transducers and activators of transcription 5) signaling pathway. To translate these basic observations we evaluated the actions of the JAK2/3 inhibitor Tofacitinib and the JAK1/2 inhibitor ruxolitinib on the gamma-c cytokine-dependent ex vivo proliferation that is characteristic of the peripheral blood mononuclear cells (PBMCs) from patients with smoldering or chronic ATL. The addition of these JAK/STAT pathway inhibitory agents markedly reduced the ex vivo proliferation of ATL cells. The choice of the JAK1/JAK3/STAT5 pathway as a target for therapy was further supported by our observation that the JAK1/JAK3/STAT5 pathway is critical in the survival of cytokine dependent ATL cell lines in studies that involved an inducible shRNA approach directed toward JAK1 or JAK3. Furthermore, results from matrix high-throughput screening for cellular or signaling analyses directed at known targets and pathways showed that the addition of a JAK1/2 inhibitor profoundly reduced the proliferation and survival of the cytokine-dependent ATL cell lines tested. Taken as a whole, on the basis of these preclinical studies that demonstrated the importance of disordered JAK1 and JAK3 signaling pathways in the survival and proliferation of ATL leukemic cells we initiated a clinical trial to evaluate the JAK1/2 inhibitor ruxolitinib in the treatment of patients with smoldering and chronic ATL. We have also focused on disorders of the JAK1/JAK3/STAT5 pathway in autoimmune diseases including those disorders associated with a high incidence of lymphoid malignancies. In particular, we demonstrated that interruption of IL-15 transpresentation with an antibody to IL-2/IL-15R beta that blocks IL-15 action or with ruxolitinib or Tofacitinib that block IL-15 signaling mediated by the JAK1/JAK3 pathway reversed the immunological and clinical disorders of two murine models of refractory celiac disease, type 1 diabetes and a murine T-cell leukemia/lymphoma model. To translate these studies to the clinic we have completed a trial using Hu-Mik-Beta-1 directed toward IL-2/IL-15R beta (CD122) that blocks IL-15 transpresentation in patients with T-cell large granular lymphocytic leukemia with neutropenia and are carrying out a clinical trial with this agent in the autoimmune neurological disease HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). Furthermore we have initiated a collaborative trial with Drs. Bana Jabri (University of Chicago) and Joseph A. Murray (Mayo Clinic, Minnesota) on patients with refractory celiac disease--a disorder with a high propensity for the development of CD8 T-cell enteropathy associated T-cell lymphoma (EATL). In summary the emerging insights concerning the IL-2/IL-2R and IL-15/IL-15R systems in normal and diseased states developed in the Waldmann Laboratory have been translated into novel strategies for treatment that includes monoclonal antibody mediated receptor directed, (daclizumab, Hu-Mik-Beta-1) cytokine mediated (IL-15) and cytokine receptor signaling directed (ruxolitinib) therapies of T-cell mediated autoimmune disorders as well as T-cell lymphoid malignancies. Furthermore, the co-discovery by Waldmann of IL-15 and his oversight of IL-15 production under cGMP conditions and his completion of a phase I clinical trial with IL-15 may lead to the development of a novel approach for the treatment of metastatic malignancy and for the inclusion of IL-15 as a component of molecular vaccines for cancer and AIDS.
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