Raina Tamakawa

RATIONALE: The immune response in sepsis is characterized by overt immune dysfunction. Studies indicate immunostimulation represents a viable therapy for patients. One study suggests a potentially protective role for interleukin 5 (IL-5) in sepsis; however, the loss of eosinophils in this disease presents a paradox. OBJECTIVES: To assess the protective and eosinophil-independent effects of IL-5 in sepsis. METHODS: We assessed the effects of IL-5 administration on survival, bacterial burden, and cytokine production after polymicrobial sepsis. In addition, we examined the effects on macrophage phagocytosis and survival using fluorescence microscopy and flow cytometry. MEASUREMENTS AND MAIN RESULTS: Loss of IL-5 increased mortality and tissue damage in the lung, IL-6 and IL-10 production, and bacterial burden during sepsis. Therapeutic administration of IL-5 improved mortality in sepsis. Interestingly, IL-5 administration resulted in neutrophil recruitment in vivo. IL-5 overexpression in the absence of eosinophils resulted in decreased mortality from sepsis and increased circulating neutrophils and monocytes, suggesting their importance in the protective effects of IL-5. Furthermore, novel data demonstrate IL-5 receptor expression on neutrophils and monocytes in sepsis. IL-5 augmented cytokine secretion, activation, phagocytosis, and survival of macrophages. Importantly, macrophage depletion before the onset of sepsis eliminated IL-5-mediated protection. The protective effects of IL-5 were confirmed in humans, where IL-5 levels were elevated in patients with sepsis. Moreover, neutrophils and monocytes from patients expressed the IL-5 receptor. CONCLUSIONS: Taken together, these data support a novel role for IL-5 on noneosinophilic myeloid populations, and suggest treatment with IL-5 may be a viable therapy for sepsis.

Previous studies have shown that telomerase facilitates DNA-damage repair and cell survival following stress. It is not clear how telomerase promotes DNA repair, or whether short-term telomerase inhibition, combined with genotoxic stress, can be exploited for cancer therapy. Here, we show that transient inhibition of telomerase activity by the specific inhibitor, GRN163L, increases the cytotoxicity of some, but not all, DNA-damaging agents. Such synergistic inhibition of growth requires the use of DNA-damaging agents that are toxic in the S/G(2) phase of the cell cycle. Notably, inhibition of Ataxia Telangiectasia Mutated (ATM) kinase, together with telomerase inhibition, synergistically increases the cytotoxicity induced by the G(2)-specific topoisomerase II inhibitor etoposide. By varying the timing of telomerase inhibition, relative to the timing of DNA damage, it is apparent that the prosurvival functions of telomerase occur at early stages of DNA damage recognition and repair. Our results suggest that the protective role of telomerase in cell cycle-restricted DNA damage repair could be exploited for combined anticancer chemotherapy.

6011 Background: This phase Ib clinical trial was performed to investigate an agonistic murine antibody to OX40 (MEDI6469) at various dose intervals prior to definitive surgical resection in patients with head and neck squamous cell carcinoma (HNSCC). Methods: 17 patients with resectable stage III-IVA HNSCC (11 = HPV-; 7 = HPV+) received MEDI6469 0.4mg/kg x 3 doses administered on day 1, day 3-4 and day 5-6 of the study, followed by definitive surgical excision and neck dissection either 2 days, 1 week or 2 weeks after infusion of anti-OX40. Primary tumor, lymph nodes and peripheral blood (PB) were obtained at baseline and at the time of surgery to characterize the circulating and tumor infiltrating lymphocyte (TIL) cell populations based on flow cytometry (FC) and multiplex immunohistochemistry (mIHC) as well as whole transcriptome analysis via RNA-sequencing (seq). Results: MEDI6469 administration was well tolerated, surgery was not delayed, and there were no grade 3 or 4 adverse events related to MEDI6469 treatment. With a median follow up of 20 months, 13/17 patients are alive without disease. 4 patients had evidence of an immunological response to treatment on FC and mIHC that peaked between 12 and 19 days after MEDI6469 infusion and was characterized by: 1) increased Ki67+CD38+ICOS+ CD4+ and CD8+ memory T-cell populations in both the TME and PB, 2) increased expression of CD39, ICOS and PD-1 on CD4+ TIL (N = 10), and 3) increased frequency of tumor-reactive, tissue resident CD39+CD103+CD8+ T cells (N = 5). RNA-seq analysis of the primary tumor in a subset of patients (N = 7) revealed significant differences between immunological responders and non-responders in genes associated with MHC I-mediated antigen processing and presentation. Subsequent immune-subtype deconvolution analysis of the RNA data revealed all responders segregated with above median levels of CD39+CD103+CD8+ T cells, consistent with flow and mIHC. Conclusions: Preoperative MEDI6469 administration is safe and resulted in increased activation and proliferation of T cells within the tumor, peaking two weeks following infusion. Immunologic changes are associated with MHC I-mediated antigen processing machinery. Clinical trial information: NCT02274155.

Supplementary Figure 2B from Telomerase Inhibition Potentiates the Effects of Genotoxic Agents in Breast and Colorectal Cancer Cells in a Cell Cycle–Specific Manner