An investigation of the Blue Bottle Experiment, a well-known lecture demonstration reaction involving the dye-catalyzed air oxidation of a reducing sugar in alkaline solution, has delineated the sequence of reactions leading to the bleaching of the dye, the regeneration of color, and so forth. Enolization of the sugar is proposed as a key step in the sequence. The first-order rate constant for this step was found to be ∼2.3 × 10 −3 min −1 with respect to total sugar concentration under the conditions used (0.184 M glucose, pH 13.3, 25°C). Measurements with an oxygen-sensing electrode on Blue-Bottle mixtures containing varying quantities of methylene blue indicated that in a usual demonstration the rate of O 2 consumption is ∼60% of the enolization rate. Small samples of the organic oxidation product were isolated and found by chromatographic and NMRspectroscopic examination to consist primarily of the 5-carbon sugar acid arabinonic acid.

Acute myeloid leukemia (AML) is a lethal hematologic malignancy characterized by an immunosuppressive milieu in the tumor microenvironment (TME) that fosters disease growth and therapeutic resistance. Hypomethylating agents (HMAs) demonstrate clinical efficacy in AML patients and exert immunomodulatory activities. In the present study, we show that guadecitabine augments both antigen processing and presentation resulting in increased AML susceptibility to T cell-mediated killing. Exposure to HMA results in the activation of the endogenous retroviral pathway with concomitant downstream amplification of critical mediators of inflammation. In an immunocompetent murine leukemia model, guadecitabine negatively regulates inhibitory accessory cells in the TME by decreasing PD-1 expressing T cells and reducing AML-mediated expansion of myeloid derived suppressor cells. Therapy with guadecitabine results in enhanced leukemia-specific immunity as manifested by increased CD4 and CD8 cells targeting syngeneic leukemia cells. We have previously reported that vaccination with AML/dendritic cell fusions elicits the expansion of leukemia-specific T cells and protects against disease relapse. In the present study, we demonstrate that vaccination in conjunction with HMA therapy results in enhanced anti-leukemia immunity and survival. The combination of a novel personalized DC/AML fusion vaccine and an HMA has therapeutic potential, and a clinical trial investigating this combination is planned.

Purpose Graft failure (GF) after hematopoietic cell transplant (HCT) occurs in 5 – 30% of patients. GF can be accompanied by neutropenia (NGF) or can result with adequate neutrophils, but loss of donor chimerism (non-neutropenic graft failure, NNGF). In this report we describe the outcomes of 95 patients treated with a second HCT for GF at the University of Minnesota; 62 with NGF and 33 with NNGF. Findings The cumulative incidence of neutrophil recovery at 42 days after second HCT was 45% for NGF and 88% for NNGF. A second GF occurred in 34 NGF (55%) and in 9 NNGF (27%) patients. The incidence of grade III–IV acute graft versus host disease (GVHD) was 8% (95% confidence interval (CI), 1 – 16%) and 12% (95% CI, 1 – 23%) for NGF and NNGF, respectively. From the 2nd HCT, 1-year overall survival (OS) was 44% (95% CI, 34 – 54%), [NNGF: 76% (95% CI, 57 – 87%) and NGF: 27% (95% CI, 17 – 39%)]. The most common cause of death after second HCT was infection (52%). Conclusions In summary, the outcomes of second HCT after NGF and NNGF are different with much worse outcomes for NGF necessitating new approaches for this complication.

We have developed a personalized vaccine whereby patient derived leukemia cells are fused to autologous dendritic cells, evoking a polyclonal T cell response against shared and neo-antigens. We postulated that the dendritic cell (DC)/AML fusion vaccine would demonstrate synergy with checkpoint blockade by expanding tumor antigen specific lymphocytes that would provide a critical substrate for checkpoint blockade mediated activation. Using an immunocompetent murine leukemia model, we examined the immunologic response and therapeutic efficacy of vaccination in conjunction with checkpoint blockade with respect to leukemia engraftment, disease burden, survival and the induction of tumor specific immunity. Mice treated with checkpoint blockade alone had rapid leukemia progression and demonstrated only a modest extension of survival. Vaccination with DC/AML fusions resulted in the expansion of tumor specific lymphocytes and disease eradication in a subset of animals, while the combination of vaccination and checkpoint blockade induced a fully protective tumor specific immune response in all treated animals. Vaccination followed by checkpoint blockade resulted in upregulation of genes regulating activation and proliferation in memory and effector T cells. Long term survivors exhibited increased T cell clonal diversity and were resistant to subsequent tumor challenge. The combined DC/AML fusion vaccine and checkpoint blockade treatment offers unique synergy inducing the durable activation of leukemia specific immunity, protection from lethal tumor challenge and the selective expansion of tumor reactive clones.

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