Eltrombopag (EP) is a small-molecule, nonpeptide thrombopoietin receptor (TPO-R) agonist that has been approved recently for the treatment of thrombocytopenia in patients with chronic immune thrombocytopenic purpura. Prior studies have shown that EP stimulates megakaryopoiesis in BM cells from patients with acute myeloid leukemia and myelodysplastic syndrome, and the results also suggested that it may inhibit leukemia cell growth. In the present study, we studied the effects of EP on leukemia cell proliferation and the mechanism of its antiproliferative effects. We found that EP leads to a decreased cell division rate, a block in G 1 phase of cell cycle, and increased differentiation in human and murine leukemia cells. Because EP is species specific in that it can only bind TPO-R in human and primate cells, these findings further suggested that the antileukemic effect is independent of TPO-R. We found that treatment with EP leads to a reduction in free intracellular iron in leukemic cells in a dose-dependent manner. Experimental increase of intracellular iron abrogated the antiproliferative and differentiation-inducing effects of EP, demonstrating that its antileukemic effects are mediated through modulation of intracellular iron content. Finally, determination of EP's antileukemic activity in vivo demonstrated its ability to prolong survival in 2 mouse models of leukemia. (Blood. 2012;120(2):386-394) IntroductionSurvival in acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS) has remained poor despite recent efforts to treat patients with novel therapeutic regimens. [1][2][3][4] In addition, complications secondary to thrombocytopenia and bleeding occur frequently in AML and MDS, leading to significant morbidity and mortality. 5,6 Given that the median age of patients with AML is close to 70 years, novel antileukemia agents with limited BM toxicity are needed to improve outcomes.Eltrombopag (EP) is an oral, nonpeptide, small-molecule thrombopoietin receptor (TPO-R) agonist that has proven efficacy in treating chronic immune thrombocytopenic purpura (ITP) and hepatitis C-related thrombocytopenia. 7,8 Despite concerns that some leukemia blast cells express TPO-R, we and others have reported previously that EP does not stimulate leukemia or MDS cell growth, but may rather lead to a modest inhibition while continuing to stimulate normal megakaryopoiesis in BM samples of patients with AML or MDS. 9,10 One study using a close chemical derivative of EP found a toxic effect on myeloid leukemia cells, suggesting that the entire substance class, including EP itself, may possess antileukemic activity. 11 Studies using cell lines further suggested that the growth-inhibitory effect of EP is not related to expression levels of However, this hypothesis has not yet been formally tested, and the mechanism through which EP exerts its potential antileukemic effect is not known. The concentrations at which EP inhibits leukemia cell proliferation in vitro are clinically achievable with few side effects and hav...

We have explored the effect of photodynamic therapy (PDT) with verteporfin on the induction and expression of contact hypersensitivity (CHS) to 2,4-dinitrofluorobenzene (DNFB) in normal mice and IL-10-deficient mice. Our results indicate that DNFB sensitized mice given PDT with verteporfin and whole body red light irradiation exhibited a significant reduction in CHS compared with control animals. Administration of rIL-12 reversed the effect(s) of PDT as did treatment of mice with anti-IL-10-neutralizing Ab. Knockout mice deficient in IL-10 were found to be resistant to the inhibitory effects of PDT. In vitro proliferative responses using spleen cells from DNFB-sensitized and PDT-treated mice showed a significantly lower response to DNBS as compared with cells from DNFB-sensitized mice or DNFB and PDT-treated IL-10-deficient mice. Finally, naive mice exposed to PDT exhibited an increase in skin IL-10 levels, which peaked between 72 and 120 h post-PDT. Together these data support the role of IL-10 as a key modulator in the inhibition of the CHS response by whole body PDT.

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Diffuse large B‐cell lymphoma (DLBCL) is the most common histologic subtype of non‐Hodgkin lymphoma and is notorious for its clinical heterogeneity. Patient outcomes can be predicted by cell‐of‐origin (COO) classification, demonstrating that the underlying transcriptional signature of malignant B‐cells informs biological behavior in the context of standard combination chemotherapy regimens. In the current study, we used mass cytometry (CyTOF) to examine tumor phenotypes at the protein level with single cell resolution in a collection of 27 diagnostic DLBCL biopsy specimens from treatment naïve patients. We found that malignant B‐cells from each patient occupied unique regions in 37‐dimensional phenotypic space with no apparent clustering of samples into discrete subtypes. Interestingly, variable MHC class II expression was found to be the greatest contributor to phenotypic diversity. Within individual tumors, a subset of cases showed multiple phenotypic subpopulations, and in one case, we were able to demonstrate direct correspondence between protein‐level phenotypic subsets and DNA mutation‐defined subclones. In summary, CyTOF analysis can resolve both intertumoral and intratumoral heterogeneity among primary samples and reveals that each case of DLBCL is unique and may be comprised of multiple, genetically distinct subclones. © 2019 International Society for Advancement of Cytometry

Treatment of mice with certain photosensitizers combined with exposure to visible light limits the development of the immunologically-mediated contact hypersensitivity (CHS) response against topically-applied chemical haptens. Understanding of the inhibitory action of photosensitizers upon the CHS response is incomplete. Benzoporphyrin derivative monoacid ring A (BPD-MA, verteporfm), a photosensitizer with immunomodulatory activity, strongly depressed CHS responses to the hapten dinilrofluorobenzene (DNFB). However, if mice were administered 1 ig of a recombinant preparation of the pro-inflammatory cytokine interleukin-12 (rIL-12), full-fledged CHS responses to DNFB ensued in animals treated with BPD-MA and light. In contrast, when rIL-12 was given in combination with an anti-IL-12 antibody the restorative effect ofrlL-12 on the CHS response of PDT-treated mice was blocked. Evaluation of the cytokine status of spleen and draining lymph node cells showed for DNFB painted animals, that the release of the immunosuppressive cytokine IL-lO was increased by PDT and rIL-12 counter-acted the increase in IJ,.lO liberation associated with PDT. These studies indicate that IL-lO formation is upregulated and the availability ofIL-12 may be limited in mice treated with PDT. These features may contribute to deficient CHS responses observed with PDT