A Pilot Study of IL-2Rα Blockade during Lymphopenia Depletes Regulatory T-cells and Correlates with Enhanced Immunity in Patients with Glioblastoma

Preclinical studies in mice have demonstrated that the prophylactic depletion of immunosuppressive regulatory T-cells (T(Regs)) through targeting the high affinity interleukin-2 (IL-2) receptor (IL-2Rα/CD25) can enhance anti-tumor immunotherapy. However, therapeutic approaches are complicated by the inadvertent inhibition of IL-2Rα expressing anti-tumor effector T-cells.To determine if changes in the cytokine milieu during lymphopenia may engender differential signaling requirements that would enable unarmed anti-IL-2Rα monoclonal antibody (MAbs) to selectively deplete T(Regs) while permitting vaccine-stimulated immune responses.A randomized placebo-controlled pilot study was undertaken to examine the ability of the anti-IL-2Rα MAb daclizumab, given at the time of epidermal growth factor receptor variant III (EGFRvIII) targeted peptide vaccination, to safely and selectively deplete T(Regs) in patients with glioblastoma (GBM) treated with lymphodepleting temozolomide (TMZ).Daclizumab treatment (n = 3) was well-tolerated with no symptoms of autoimmune toxicity and resulted in a significant reduction in the frequency of circulating CD4+Foxp3+ TRegs in comparison to saline controls (n = 3)( p = 0.0464). A significant (p<0.0001) inverse correlation between the frequency of TRegs and the level of EGFRvIII specific humoral responses suggests the depletion of TRegs may be linked to increased vaccine-stimulated humoral immunity. These data suggest this approach deserves further study.ClinicalTrials.gov NCT00626015

Gene Therapy-Mediated Reprogramming Tumor Infiltrating T Cells Using IL-2 and Inhibiting NF-κB Signaling Improves the Efficacy of Immunotherapy in a Brain Cancer Model

Immune-mediated gene therapy using adenovirus expressing Flt3 ligand and thymidine kinase followed by ganciclovir administration (Flt3/TK) effectively elicits tumor regression in preclinical glioma models. Herein, we assessed new strategies to optimize Flt3L/TK therapeutic efficacy in a refractory RG2 orthotopic glioblastoma model. Specifically, we aimed to optimize the therapeutic efficacy of Flt3L/TK treatment in the RG2 model by overexpressing the following genes within the brain tumor microenvironment: 1) a TK mutant with enhanced cytotoxicity (SR39 mutant TK), 2) Flt3L-IgG fusion protein that has a longer half-life, 3) CD40L to stimulate DC maturation, 4) T helper cell type 1 polarizing dendritic cell cytokines interleukin-12 or C-X-C motif ligand 10 chemokine (CXCL)-10, 5) C-C motif ligand 2 chemokine (CCL2) or C-C motif ligand 3 chemokine (CCL3) to enhance dendritic cell recruitment into the tumor microenvironment, 6) T helper cell type 1 cytokines interferon-γ or interleukin-2 to enhance effector T-cell functions, and 7) IκBα or p65RHD (nuclear factor kappa-B [NF-κB] inhibitors) to suppress the function of Foxp3+ Tregs and enhanced effector T-cell functions. Anti-tumor immunity and tumor specific effector T-cell functions were assessed by cytotoxic T lymphocyte assay and intracellular IFN-γ staining. Our data showed that overexpression of interferon-γ or interleukin-2, or inhibition of the nuclear factor kappa-B within the tumor microenvironment, enhanced cytotoxic T lymphocyte-mediated immune responses and successfully extended the median survival of rats bearing intracranial RG2 when combined with Flt3L/TK. These findings indicate that enhancement of T-cell functions constitutes a critical therapeutic target to overcome immune evasion and enhance therapeutic efficacy for brain cancer. In addition, our study provides novel targets to be used in combination with immune-therapeutic strategies for glioblastoma, which are currently being tested in the clinic.Fil: Mineharu, Yohei. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Muhammad, AKM Ghulam. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Yagiz, Kader. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Candolfi, Marianela. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kroeger, Kurt M.. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Xiong, Weidong. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Puntel, Mariana. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Liu, Chunyan. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Levy, Eva. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Lugo, Claudia. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Kocharian, Adrina. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados UnidosFil: Allison, James P.. Howard Hughes Medical Institute; Estados UnidosFil: Curran, Michael A.. Howard Hughes Medical Institute; Estados UnidosFil: Lowenstein, Pedro R.. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados Unidos. University of Michigan; Estados UnidosFil: Castro, Maria G.. Cedars Sinai Medical Center. Gene Therapeutics Research Institute; Estados Unidos. University of California at Los Angeles; Estados Unidos. University of Michigan; Estados Unido