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

Activation of Wnt signaling in hematopoietic regeneration

Hematopoietic stem cells (HSCs) respond to injury by rapidly proliferating and regenerating the hematopoietic system. Little is known about the intracellular programs that are activated within HSCs during this regenerative process and how this response may be influenced by alterations in signals from the injured microenvironment. Here we have examined the regenerating microenvironment and find that following injury it has an enhanced ability to support HSCs. During this regenerative phase, both hematopoietic and stromal cell elements within the bone marrow microenvironment show increased expression of Wnt10b, which can function to enhance growth of hematopoietic precursors. In addition, regenerating HSCs show increased activation of Wnt signaling, suggesting that microenvironmental changes in Wnt expression after injury may be integrated with the responses of the hematopoietic progenitors. Cumulatively, our data reveal that growth signals in the hematopoietic system are re-activated during injury, and provide novel insight into the influence of the microenviromnent during regeneratio

A Supramolecular Vaccine Platform Based on α‑Helical Peptide Nanofibers

A supramolecular peptide vaccine system was designed in which epitope-bearing peptides self-assemble into elongated nanofibers composed almost entirely of α-helical structure. The nanofibers were readily internalized by antigen presenting cells and produced robust antibody, CD4+ T-cell, and CD8+ T-cell responses without supplemental adjuvants in mice. Epitopes studied included a cancer B-cell epitope from the epidermal growth factor receptor class III variant (EGFRvIII), the universal CD4+ T-cell epitope PADRE, and the model CD8+ T-cell epitope SIINFEKL, each of which could be incorporated into supramolecular multiepitope nanofibers in a modular fashion

<i>In vivo</i> effects of daclizumab on the effector T-cell to regulatory T-cell ratio.

<p>(A–B) Effector T-cells (CD4⁺ or CD8⁺) to T_Reg ratios were derived by dividing the absolute number of effector T-cells by the absolute number of T_Regs at the indicated time-points; the absolute number of cells was determined by a combination of CBC and FACS analysis. The ratios of effector T-cells to T_Regs as compared to baseline were generated by dividing the individual patient CD4⁺∶T_Reg or CD8⁺∶T_Reg ratio at every time point by the ratio at vaccine 1 (V-1 = baseline). A two sample t-test averaged over the V-2, V-3 and LP time-points was utilized to examine the difference between the daclizumab and saline groups in the CD4⁺∶T_Reg (p = 0.0757) and CD8⁺∶T_Reg (p = 0.0153) ratios.</p

The frequency of T_Regs and anti-PEPvIII humoral responses are inversely correlated.

<p>Patient sera from peripheral blood (vaccine 4) and leukapheresis samples were analyzed for levels of anti-PEPvIII antibodies and humoral responses were plotted against the frequency of T_Regs (Foxp3⁺ of CD4⁺). Assuming the assessments within individuals are independent, the Spearman correlation coefficient for both saline and daclizumab treated patients overall is (R = −0.93, p<0.0001).</p