A pilot study of IL-2Rα blockade during lymphopenia depletes regulatory T-cells and correlates with enhanced immunity in patients with glioblastoma.
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BACKGROUND: 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. OBJECTIVE: 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. METHODOLOGY: 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). RESULTS AND CONCLUSIONS: 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. TRIAL REGISTRATION: ClinicalTrials.gov NCT00626015.
Published Version (Please cite this version)
Sampson, John H, Robert J Schmittling, Gary E Archer, Kendra L Congdon, Smita K Nair, Elizabeth A Reap, Annick Desjardins, Allan H Friedman, et al. (2012). A pilot study of IL-2Rα blockade during lymphopenia depletes regulatory T-cells and correlates with enhanced immunity in patients with glioblastoma. PLoS One, 7(2). p. e31046. 10.1371/journal.pone.0031046 Retrieved from https://hdl.handle.net/10161/16110.
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Current research activities involve the immunotherapeutic targeting of a tumor-specific mutation in the epidermal growth factor receptor. Approaches used to target this tumor-specific epitope include unarmed and radiolabeled antibody therapy and cell mediated approaches using peptide vaccines and dendritic cells. Another area of interest involves drug delivery to brain tumors. Translational and clinical work is carried out in this area to formulate the relationship between various direct intratumoral infusion parameters and drug distribution within brain tumors and normal brain.
The Duke Brain Tumor Immunotherapy Program (BTIP) has an emphasis on translational research in Neuro-Oncology. There are two main areas of study. The first is novel mechanisms of delivery of large molecular weight molecules, such as monoclonal antibodies, throughout brain intersitial space using novel intracerebral infusion techniques developed by this laboratory. Studies exploring this technology are undertaken in both small and large laboratory animals and patients with brain tumors.
The other focus of the BTIP is translational immunotherapy. In this line of work, dendritic cell vaccination strategies and adoptive T-cell strategies have been developed to target novel and well-characterized tumor-specific antigens in patients with brain tumors. The BTIP integrates well with and works closely with the Preston Robert Tisch Brain Tumor Center at Duke. The BTIP is well funded and currently holds seven NIH grants, including a SPORE in Brain Cancer grant. There are a large number of investigators at various levels so that students will get exposure to various levels of research and mentorship.
My current research focus involves the delivery of therapeutic agents for the treatment of central nervous system neoplasia. Utilizing athymic rat models of central nervous system neoplasia I am investigating compartmental approaches to increase therapeutic efficacy of chemotherapeutic agents and immunoconjugates. Preclinical testing in athymic rats of intrathecal administration of melphalan and 4-hydroperoxycyclophosphamide have resulted in the FDA granting investigational new drug protocols for the treatment of neoplastic meningitis using these two agents. I am also currently involved with the selective intraarterial administration of alkylator resistance modulators to treat intraparechymal brain tumors which are resistant to conventional alkylator therapy. I am also working in collaboration with Dr. Darell Bigner on the characterization of MAbs that react with the epidermal growth factor receptor variant III mutant, a tumor specific antigen.
I have 22 years of experience in the field of cancer vaccines and immunotherapy and I am an accomplished T cell immunologist. Laboratory website:
Current projects in the Nair Laboratory:
1] Dendritic cell vaccines using tumor-antigen encoding RNA (mRNA, total tumor RNA, amplified tumor mRNA)
2] Local immune receptor modulation using mRNA that encodes for antibodies, receptor-ligands, cytokines, chemokines and toll-like receptors (current target list: CTLA4, GITR, PD1, TIM3, LAG3, OX40 and 41BB)
3] Combination therapies for cancer: cytotoxic therapy (radiation, chemo and oncolytic poliovirus therapy) with dendritic cell-based vaccines and immune checkpoint blockade
4] Adoptive T cell therapy using tumor RNA-transfected dendritic cells to expand tumor-specific T cells ex vivo
5] Adoptive T cell therapy using PSMA CAR (chimeric antigen receptor) RNA-transfected T cells
6] Direct injection of tumor antigen encoding RNA (targeting antigens to dendric cells in vivo using nanoparticles and aptamers)
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