David J Liewehr

National Cancer Institute (USA), Maryland, United States

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Publications (96)584.96 Total impact

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    ABSTRACT: The nucleoside reverse transcriptase inhibitor zidovudine (AZT) induces genotoxic damage that includes centrosomal amplification (CA > 2 centrosomes/cell) and micronucleus (MN) formation. Here we explored these end points in mice deficient in DNA repair and tumor suppressor function to evaluate their effect on AZT-induced DNA damage. We used mesenchymal-derived fibroblasts cultured from C57BL/6J mice that were null and wild type (WT) for Xpa, and WT, haploinsufficient and null for p53 (6 different genotypes). Dose-responses for CA formation, in cells exposed to 0, 10, and 100 μM AZT for 24 hr, were observed in all genotypes except the Xpa(+/+)p53(+/−) cells, which had very low levels of CA, and the Xpa(−/−)p53(−/−) cells, which had very high levels of CA. For CA there was a significant three-way interaction between Xpa, p53, and AZT concentration, and Xpa(−/−) cells had significantly higher levels of CA than Xpa(+/+) cells, only for p53(+/−) cells. In contrast, the MN and MN + chromosomes (MN + C) data showed a lack of AZT dose response. The Xpa(−/−) cells, with p53(+/+) or (+/−) genotypes, had levels of MN and MN + C higher than the corresponding Xpa(+/+) cells. The data show that CA is a major event induced by exposure to AZT in these cells, and that there is a complicated relationship between AZT and CA formation with respect to gene dosage of Xpa and p53. The loss of both genes resulted in high levels of damage, and p53 haploinsufficicency strongly protected Xpa(+/+) cells from AZT-induced CA damage. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc.
    Environmental and Molecular Mutagenesis 07/2014; · 3.71 Impact Factor
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    ABSTRACT: The downstream targets of hypoxia inducible factor-1 alpha (HIF-1alpha) play an important role in tumor progression and angiogenesis. Therefore, inhibition of HIF-mediated transcription has potential in the treatment of cancer. One attractive strategy for inhibiting HIF activity is the disruption of the HIF-1alpha/p300 complex, as p300 is a crucial coactivator of hypoxia-inducible transcription. Several members of the epidithiodiketopiperazine (ETP) family of natural products have been shown to disrupt the HIF-1alpha/p300 complex in vitro; namely, gliotoxin, chaetocin, and chetomin. Here, we further characterized the molecular mechanisms underlying the antiangiogenic and antitumor effects of these ETPs using a preclinical model of prostate cancer. In the rat aortic ring angiogenesis assay, gliotoxin, chaetocin, and chetomin significantly inhibited microvessel outgrowth at a GI50 of 151, 8, and 20 nM, respectively. In vitro co-immunoprecipitation studies in prostate cancer cell extracts demonstrated that these compounds disrupted the HIF-1alpha/p300 complex. The downstream effects of inhibiting the HIF-1alpha/p300 interaction were evaluated by determining HIF-1alpha target gene expression at the mRNA and protein levels. Dose-dependent decreases in levels of secreted VEGF were detected by ELISA in the culture media of treated cells, and the subsequent downregulation of VEGFA, LDHA, and ENO1 HIF-1alpha target genes were confirmed by semi-quantitative real-time PCR. Finally, treatment with ETPs in mice bearing prostate tumor xenografts resulted in significant inhibition of tumor growth. These results suggest that directly targeting the HIF-1alpha/p300 complex with ETPs may be an effective approach for inhibiting angiogenesis and tumor growth.
    Molecular Cancer 04/2014; 13(1):91. · 5.13 Impact Factor
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    ABSTRACT: Brain metastases of breast cancer cause neurocognitive damage and are incurable. We evaluated a role for temozolomide in the prevention of brain metastases of breast cancer in experimental brain metastasis models. Temozolomide was administered in mice following earlier injection of brain-tropic human epidermal growth factor receptor 2 (HER2)-positive Jimt1- BR3 and triple negative 231-BR-EGFP sublines, the latter with and without expression of 06-methylguanine-DNA methyltransferase (MGMT). Additionally, the percentage of MGMT-positive tumor cells in 62 patient-matched sets of breast cancer primary tumors and resected brain metastases was determined immunohistochemically. Temozolomide, when dosed at 50, 25, 10 or 5 mg/kg, 5 days/week, beginning 3 days after inoculation, completely prevented the formation of experimental brain metastases from MGMT-negative 231-BR-EGFP cells. At a 1 mg/kg dose, temozolomide prevented 68% of large brain metastases, and was ineffective at a dose of 0.5 mg/kg. When the 50 mg/kg dose was administered beginning on days 18 or 24, temozolomide efficacy was reduced or absent. Temozolomide was ineffective at preventing brain metastases in MGMT-transduced 231-BR-EGFP and MGMT-expressing Jimt-1-BR3 sublines. In 62 patient-matched sets of primary breast tumors and resected brain metastases, 43.5% of the specimens had concordant low MGMT expression, while in another 14.5% of sets high MGMT staining in the primary tumor corresponded with low staining in the brain metastasis. Temozolomide profoundly prevented the outgrowth of experimental brain metastases of breast cancer in an MGMT-dependent manner. These data provide compelling rationale for investigating the preventive efficacy of temozolomide in a clinical setting.
    Clinical Cancer Research 03/2014; · 7.84 Impact Factor
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    ABSTRACT: Mutant Ras oncogenes produce proteins that are unique to cancer cells and represent attractive targets for vaccine therapy. We have shown previously that vaccinating cancer patients with mutant ras peptides is feasible and capable of inducing a specific immune response against the relevant mutant proteins. Here, we tested the mutant ras peptide vaccine administered in combination with low dose interleukin-2 (IL-2) or/and granulocyte-macrophage colony-stimulating factor (GM-CSF) in order to enhance the vaccine immune response. 5000mug of the corresponding mutant ras peptide was given subcutaneously (SQ) along with IL-2 (Arm A), GM-CSF (Arm B) or both (Arm C). IL-2 was given SQ at 6.0 million IU/m2/day starting at day 5, 5 days/week for 2 weeks. GM-CSF was given SQ in a dose of 100mug/day one day prior to each ras peptide vaccination for 4 days. Vaccines were repeated every 5 weeks on arm A and C, and every 4 weeks on arm B, for a maximum of 15 cycles or until disease progression. We treated 53 advanced cancer patients (38 with colorectal, 11 with pancreatic, 1 with common bile duct and 3 with lung) on 3 different arms (16 on arm A, 18 on arm B, and 19 on arm C). The median progression free survival (PFS) and overall survival (OS) was 3.6 and 16.9 months, respectively, for all patients evaluable for clinical response (n = 48). There was no difference in PFS or OS between the three arms (P = 0.73 and 0.99, respectively). Most adverse events were grade 1-2 toxicities and resolved spontaneously. The vaccine induced an immune response to the relevant ras peptide in a total of 20 out of 37 evaluable patients (54%) by ELISPOT, proliferative assay, or both. While 92.3% of patients on arm B had a positive immune response, only 31% of patients on arm A and 36% of patients on arm C had positive immune responses (P = 0.003, Fisher's exact test). The reported data showed that IL-2 might have a negative effect on the specific immune response induced by the relevant mutant ras vaccine in patients with advanced cancer. This observation deserves further investigations. Trial registration: NCI97C0141.
    Journal of Translational Medicine 02/2014; 12(1):55. · 3.46 Impact Factor
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    ABSTRACT: We recently reported the clinical results of a Phase I trial combining ipilimumab with a vaccine containing transgenes for prostate-specific antigen (PSA) and for a triad of costimulatory molecules (PROSTVAC) in patients with metastatic castration-resistant prostate cancer. Thirty patients were treated with escalating ipilimumab and a fixed dose of vaccine. Of 24 chemotherapy-naïve patients, 58 % had a PSA decline. Combination therapy did not exacerbate the immune-related adverse events associated with ipilimumab. Here, we present updated survival data and an evaluation of 36 immune cell subsets pre- and post-therapy. Peripheral blood mononuclear cells were collected before therapy, at 13 days and at 70 days post-initiation of therapy, and phenotyped by flow cytometry for the subsets of T cells, regulatory T cells, natural killer cells, and myeloid-derived suppressor cells. Associations between overall survival (OS) and immune cell subsets prior to treatment, and the change in a given immune cell subset 70 days post-initiation of therapy, were evaluated. The median OS was 2.63 years (1.77-3.45). There were trends toward associations for longer OS and certain immune cell subsets before immunotherapy: lower PD-1(+)Tim-3(NEG)CD4EM (P = 0.005, adjusted P = 0.010), higher PD-1(NEG)Tim-3(+)CD8 (P = 0.002, adjusted P = 0.004), and a higher number of CTLA-4(NEG) Tregs (P = 0.005, adjusted P = 0.010). We also found that an increase in Tim-3(+) natural killer cells post- versus pre-vaccination associated with longer OS (P = 0.0074, adjusted P = 0.015). These results should be considered as hypothesis generating and should be further evaluated in larger immunotherapy trials.
    Cancer Immunology and Immunotherapy 02/2014; · 3.64 Impact Factor
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    ABSTRACT: PSA-TRICOM (PROSTVAC) is a novel vector-based vaccine designed to generate a robust immune response against prostate-specific antigen (PSA)-expressing tumor cells. The purpose of this report is to present an overview of both published studies and new data in the evaluation of immune responses to the PSA-TRICOM vaccine platform, currently in phase III testing. Of 104 patients tested for T-cell responses, 57% (59/104) demonstrated a ≥2-fold increase in PSA-specific T cells 4 weeks after vaccine (median 5-fold increase) compared with pre-vaccine, and 68% (19/28) of patients tested mounted post-vaccine immune responses to tumor-associated antigens not present in the vaccine (antigen spreading). The PSA-specific immune responses observed 28 days after vaccine (i.e., likely memory cells) are quantitatively similar to the levels of circulating T cells specific for influenza seen in the same patients. Measurements of systemic immune response to PSA may underestimate the true therapeutic immune response (as this does not account for cells that have trafficked to the tumor) and does not include antigen spreading. Furthermore, although the entire PSA gene is the vaccine, only one epitope of PSA is evaluated in the T-cell responses. Because this therapeutic vaccine is directed at generating a cellular/Th1 immune response (T-cell costimulatory molecules and use of a viral vector), it is not surprising that less than 0.6% of patients (2/349) tested have evidence of PSA antibody induction following vaccine. This suggests that post-vaccine PSA kinetics were not affected by PSA antibodies. An ongoing phase III study will evaluate the systemic immune responses and correlation with clinical outcomes. Cancer Immunol Res; 2(2); 133-41. ©2013 AACR.
    Cancer immunology research. 02/2014; 2(2):133-41.
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    ABSTRACT: Despite major therapeutic advances in the management of patients with breast cancer, central nervous system (CNS) metastases remain an intractable problem, particularly in patients with metastatic HER2-positive and triple-negative breast cancer. As systemic therapies to treat extracranial disease improve, some patients are surviving longer, and the frequency of CNS involvement seems to be increasing. Furthermore, in the early-stage setting, the CNS remains a potential sanctuary site for relapse. This review highlights advances in the development of biologically relevant preclinical models, including the development of brain-tropic cell lines for testing of agents to prevent and treat brain metastases, and summarizes our current understanding of the biology of CNS relapse. From a clinical perspective, a variety of therapeutic approaches are discussed, including methods to improve drug delivery, novel cytotoxic agents, and targeted therapies. Challenges in current trial design and endpoints are reviewed. Finally, we discuss promising new directions, including novel trial designs, correlative imaging techniques, and enhanced translational opportunities. Clin Cancer Res; 19(23); 6404-18. ©2013 AACR.
    Clinical Cancer Research 12/2013; 19(23):6404-18. · 7.84 Impact Factor
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    ABSTRACT: Objectives Anti-CD20 (rituximab), anti-CD52 (alemtuzumab), anti-CD22 (BL22, HA22), and anti-CD25 (Oncotac) are therapeutic options that are the mainstay or in preclinical development for the treatment of chronic lymphocytic leukemia (CLL). Studies suggest that levels of surface antigen expression may affect response to monoclonal antibody-based therapy. Methods Using the flow cytometric Quantibrite method (BD Biosciences, San Jose, CA) to determine antibodies bound per cell, we quantified the levels of surface expression of CD20, CD22, CD25, and CD52 in CLL cells from 28 untreated patients. Results The CLL cells in all cases expressed CD20, CD22, and CD52 but 4 (14%) cases were negative for CD25. Although the ranking of levels of expression from highest to lowest was CD52, CD20, CD22, and CD25, the level of antigen expression on any specific case could not be accurately predicted. Conclusions Quantification of antigens might be useful in evaluating new antigens to target for therapy and may provide a systematic approach to selecting individualized therapy in CLL.
    American Journal of Clinical Pathology 12/2013; 140(6):813-8. · 2.88 Impact Factor
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    ABSTRACT: Eradication of minimal residual disease (MRD) after allotransplantation in persons with chronic lymphocytic leukemia (CLL) is associated with lower rates of relapse. Rapid engraftment of donor lymphocyte elements may contribute to MRD control but it remains unclear if this strategy will benefit patients. Here we report incidence of MRD eradication and graft versus host disease (GvHD) in persons with rapid versus later donor T-lymphocyte engraftment after lymphodepleting chemotherapy and reduced intensity conditioning (RIC) allotransplantation. Twenty-seven subjects received lymphodepleting chemotherapy to facilitate donor engraftment followed by fludarabine and cyclophosphamide RIC and a blood cell allograft. MRD was monitored by multicolor flow cytometry post transplantation. Complete donor T-lymphoid (TLC) and myeloid (MC) chimerism were achieved in 25 subjects at a median of 28 days (range 14-60 days) and 21 days (range 14-180 days). Achieving complete donor TLC by day 14 versus day ≥28 correlated with occurrence of ≥grade-2 acute GvHD (90% [95% confidence interval (CI), 78-100%] versus 35% [95% CI, 16-54%], P=0.014) and better control of minimal residual disease in the bone marrow at day 100, median 0% (range, 0-0.1%) versus 8.5% (range, 0-92%; P=0.016). Among 11 persons with early donor TLC none had progressive disease (PD) and 7 died of treatment related mortality (TRM). In persons with later development of TLC 8 of 16 had PD and 2 died of TRM. Time to donor myeloid chimerism had no impact on outcomes. Rapid establishment of donor TLC results in more complete eradication of early MRD but greater incidence of acute GvHD and TRM in persons with CLL undergoing RIC allotransplantation.
    Experimental hematology 05/2013; · 3.11 Impact Factor
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    ABSTRACT: The interaction between CD27 and its ligand, CD70, has been implicated in regulating cellular immune responses to cancer. In this article, we report on the role of soluble CD27 (sCD27) in T cell activation and its elevation in the serum of cancer patients after immunotherapy. In vitro, sCD27 is preferentially derived from activated CD4(+) T cells. Adding sCD27 to stimulated PBMCs increases T cell activation and proliferation, and is associated with the immunologic synapse-related proteins myosin IIA, high mobility group box 1, and the TCR Vβ-chain. The pool of serum sCD27 is shown to be greater in healthy donors than in cancer patients. However, metastatic cancer patients treated with immunotherapy showed a significant increase in the serum sCD27-pool posttherapy (p < 0.0005); there was also an increased trend toward an association between enhanced sCD27-pool posttherapy and overall survival (p = 0.022). The identification of sCD27 as an immune modulator associated with enhanced human T cell activation in vitro and in vivo provides a rationale for developing new immunotherapeutic strategies aimed at enhancing sCD27 for treating cancer and potentially other diseases.
    The Journal of Immunology 05/2013; · 5.52 Impact Factor
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    ABSTRACT: BACKGROUND: There is currently no standard of care for the second-line treatment of advanced pancreatic cancer. The aim of this analysis was to compare the different therapeutic approaches in this setting. METHODS: We carried out a systematic analysis of second-line studies in advanced pancreatic cancer that have progressed on or following gemcitabine and published or presented from 2000 to 2012. RESULTS: Forty-four clinical trials (t) were identified; of which 34 met the inclusion criteria treating an aggregate total of 1503 patients (n). Patients who received treatments (t: 33; n: 1269) had a median overall survival (OS) of 6 months compared with 2.8 months for patients who received best supportive care only (t: 2; n: 234) (P = 0.013). The gemcitabine and platinum-based combination (t: 5; n: 154) provided a median progression-free survival and OS of 4 and 6 months compared with 1.6 and 5.3 for the rest of the regimens (t: 29; n: 1349) (P = 0.059 and 0.10, respectively) and 2.9 and 5.7 for the combination of 5-fluorouracil and platinum agents (t: 12; n: 450) (P = 0.60 and 0.22, respectively). CONCLUSION(S): Although not conclusive, these data showed that the advantage of second-line chemotherapy in pancreatic cancer is very limited and there is a need for more studies.
    Annals of Oncology 05/2013; · 7.38 Impact Factor
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    ABSTRACT: PURPOSE: Romidepsin is a histone deacetylase inhibitor (HDI) approved for the treatment of both cutaneous and peripheral T cell lymphoma (CTCL and PTCL). During development, a thorough assessment of cardiac toxicity was performed. EXPERIMENTAL DESIGN: A phase II single-agent non-randomized study of romidepsin was performed in patients with CTCL and PTCL who had progressed after at least one prior systemic therapy. RESULTS: Results for the first 42 patients enrolled on the NCI 1312 Phase II study of romidepsin in CTCL or PTCL demonstrated no cardiac toxicity based on serial electrocardiograms, troponins and MUGA scans/echocardiograms. The cardiac assessments reported herein confirm the safety of romidepsin among 131 enrolled patients, while supporting a role for electrolyte replacement. Heart rate increased an average 11 bpm following romidepsin infusion; there was no evidence of increased arrhythmia. Criteria for potassium/magnesium replacement were met prior to 55% of 1365 romidepsin doses; an association with hypoalbuminemia was confirmed. We propose a mechanism for ST segment flattening and depression, the most common electrocardiogram abnormalities observed: HDI-induced alteration of the activity or expression of KATP channels. In addition, examination of the variants of the active transporter of romidepsin, ABCB1, demonstrated a trend towards smaller heart rate changes in the peri-infusion period among wild type compared to variant diplotypes. CONCLUSIONS: We conclude that in the context of appropriate attention to electrolyte levels, the data support the cardiac safety of romidepsin.
    Clinical Cancer Research 04/2013; · 7.84 Impact Factor
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    ABSTRACT: Brain metastases of breast cancer occur in more than one-third of metastatic breast cancer patients whose tumors overexpress HER2 or are triple negative. Brain colonization of cancer cells occurs in a unique environment, containing microglia, oligodendrocytes, astrocytes, and neurons. Although a neuroinflammatory response has been documented in brain metastasis, its contribution to cancer progression and therapy remains poorly understood. Using an experimental brain metastasis model of breast cancer, we characterized the brain metastatic microenvironment of brain tropic, HER2-transfected MDA-MB-231 human breast carcinoma cells (231-BR-HER2). A previously unidentified subpopulation of metastasis-associated astrocytes expressing phosphorylated platelet-derived growth factor receptor β (at tyrosine 751; p751-PDGFRβ) was identified around perivascular brain micrometastases. This subpopulation of p751-PDGFRβ(+) astrocytes was also identified in human brain metastases from eight different craniotomy specimens and in primary cultures of astrocyte-enriched glial cells. Previously, we reported that pazopanib, a multispecific tyrosine kinase inhibitor, prevented the outgrowth of 231-BR-HER2 large brain metastases by 73%. Here, we evaluated the effect of pazopanib on the brain neuroinflammatory microenvironment. Pazopanib treatment resulted in 70% (P = 0.023) decrease of the p751-PDGFRβ(+) astrocyte population, at the lowest dose of 30 mg/kg, twice daily. Collectively, the data identify a new subpopulation of activated astrocytes in the subclinical perivascular stage of brain metastases and show that they are inhibitable by pazopanib, suggesting its potential to prevent the development of subclinical perivascular micrometastases in breast cancer patients.
    American Journal Of Pathology 04/2013; · 4.60 Impact Factor
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    ABSTRACT: Flow cytometric (FC) enumeration of abnormal plasma cells (APCs) for diagnosis and prognostication of plasma cell dyscrasias (PCD) is challenging. We studied antigen expression in normal plasma cells (NPC) (N = 34) and APC in a series of unselected PCD (N = 59). NPC subpopulations often demonstrated CD19(-), CD20(+), CD45(-) or dim and CD56(+), an immunophenotype observed in PCD. However abnormal CD81 was only observed in APCs (APC detection sensitivity 95%; specificity 100%). We evaluated differences in antigen expression patterns among MGUS (N = 14), SMM (N = 35) and MM (N = 10), finding the combination of CD45 and CD56 helpful in differentiating MGUS from SMM and MM (p = 0.0002).
    Leukemia research 01/2013; · 2.36 Impact Factor
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    ABSTRACT: Purpose: Translating clinically valid genomic discoveries into practice is hinged not only on technologic advances, but also on nurses-the largest global contingent of health providers-acquiring requisite competencies to apply these discoveries in clinical care. The study aim was to assess practicing nurse attitudes, practices, receptivity, confidence, and competency of integrating genomics into nursing practice. Design: A convenience sample of practicing nurses was recruited to complete an online survey that assessed domains from Roger's Diffusion of Innovations Theory and used family history utilization as the basis for competency assessment. Methods: Results were tabulated and analyzed using descriptive statistical techniques. Findings: Two-hundred-thirty-nine licensed registered nurses, 22 to 72 years of age, with a median of 20 years in practice, responded, for an overall response rate of 28%. Most were White (83%), female (92%), and held baccalaureate degrees (56%). Seventy-one percent considered genetics to be very important to nursing practice; however, 81% rated their understanding of the genetics of common diseases as poor or fair. Per-question response rates varied widely. Instrument assessment indicated that modifications were necessary to decrease respondent burden. Conclusions: Respondents' perceived genomic competency was inadequate, family history was not routinely utilized in care delivery, and the extent of family history varied widely. However, most nurses indicated interest in pursuing continuing genomic education. Clinical Relevance: Findings from this study can lead to the development of targeted education that will facilitate optimal workforce preparation for the ongoing influx of genetics and genomics information, technologies, and targeted therapies into the healthcare arena. This pilot study provides a foundation on which to build the next step, which includes a national nursing workforce study.
    Journal of Nursing Scholarship 12/2012; 44(4):428-436. · 1.61 Impact Factor
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    ABSTRACT: Background Previous studies identified the human nonmetastatic gene 23 (NME1, hereafter Nm23-H1) as the first metastasis suppressor gene. An inverse relationship between Nm23-H1 and expression of lysophosphatidic acid receptor 1 gene (LPAR1, also known as EDG2 or hereafter LPA1) has also been reported. However, the effects of LPA1 inhibition on primary tumor size, metastasis, and metastatic dormancy have not been investigated. Methods The LPA1 inhibitor Debio-0719 or LPA1 short hairpinned RNA (shRNA) was used. Primary tumor size and metastasis were investigated using the 4T1 spontaneous metastasis mouse model and the MDA-MB-231T experimental metastasis mouse model (n = 13 mice per group). Proliferation and p38 intracellular signaling in tumors and cell lines were determined by immunohistochemistry and western blot to investigate the effects of LPA1 inhibition on metastatic dormancy. An analysis of variance-based two-tailed t test was used to determine a statistically significant difference between treatment groups. Results In the 4T1 spontaneous metastasis mouse model, Debio-0719 inhibited the metastasis of 4T1 cells to the liver (mean = 25.2 liver metastases per histologic section for vehicle-treated mice vs 6.8 for Debio-0719-treated mice, 73.0% reduction, P < .001) and lungs (mean = 6.37 lesions per histologic section for vehicle-treated mice vs 0.73 for Debio-0719-treated mice, 88.5% reduction, P < .001), with no effect on primary tumor size. Similar results were observed using the MDA-MB-231T experimental pulmonary metastasis mouse model. LPA1 shRNA also inhibited metastasis but did not affect primary tumor size. In 4T1 metastases, but not primary tumors, expression of the proliferative markers Ki67 and pErk was reduced by Debio-0719, and phosphorylation of the p38 stress kinase was increased, indicative of metastatic dormancy. Conclusion The data identify Debio-0719 as a drug candidate with metastasis suppressor activity, inducing dormancy at secondary tumor sites.
    CancerSpectrum Knowledge Environment 08/2012; 104(17):1306-19. · 14.07 Impact Factor
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    ABSTRACT: Brain metastases of breast and other cancers remain resistant to chemotherapeutic regimens that are effective systemically, in part due to the blood-brain barrier. We report that TPI-287, a new microtubule-stabilizing agent, displays in vitro cytotoxic activity similar to taxanes and epothilones. Unlike the taxanes, TPI-287 is permeable through the blood-brain barrier. Brain-to-plasma ratios of TPI-287 after a single injection typically exceeded one and were as high as 63.8 in the rat and 14.1 in the mouse. A brain-tropic derivative of the MDA-MB-231 triple-negative breast cancer cell line, 231-BR, was used to test whether TPI-287 may be efficacious at preventing or treating brain metastases. TPI-287 had growth inhibitory effects comparable with paclitaxel when 231-BR tumor cells were injected into the mammary fat pad. Brain metastatic colonization was determined by intracardiac injection of 231-BR cells, with treatment beginning on day 3 to 4 postinjection, culminating in a histologic count of brain metastases in brains necropsied days 25 to 28 postinjection. In this assay, paclitaxel, ixabepilone, and nab paclitaxel did not have significant inhibitory activity. TPI-287 was ineffective in the same assay using a 6 mg/kg every week schedule; however an 18 mg/kg dose delivered on days 3, 7, and 11 significantly reduced the outgrowth of brain metastases (55% reduction, P = 0.028) and reduced proliferation in brain metastases (16% reduction, P = 0.008). When TPI-287 treatment was delayed until days 18, 22, and 26 postinjection, efficacy was reduced (17% reduction, not significant). These data suggest that TPI-287 may have efficacy when administered early in the course of the disease. Mol Cancer Ther; 11(9); 1959-67. ©2012 AACR.
    Molecular Cancer Therapeutics 05/2012; 11(9):1959-67. · 5.60 Impact Factor
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    ABSTRACT: CD4(+)FoxP3(+) regulatory T cells (Tregs) have been shown to suppress T cell-mediated host immune responses against self- and nonself-antigens; however, the impact of CD4(+) Tregs on human antitumor immune responses and their influence on cancer treatment are unknown. In the present study, we explored the factors that influence CD4(+) Treg reconstitution in patients receiving adoptive immunotherapy following conditioning regimens designed to enhance T-cell function and evaluated potential associations between CD4(+) Treg levels and clinical responses to therapy. The analysis of 4 trials employing nonmyeloablative chemotherapy with or without total body irradiation (TBI) before adoptive T-cell transfer revealed that the percentage and number of reconstituting CD4(+)FoxP3(+) Tregs observed in the peripheral blood was higher in nonresponders than in responders. The addition of TBI resulted in a further depletion of CD4(+) Tregs, and the degree of depletion was dependent on the TBI dose. The number of administered doses of IL-2 was found to be positively associated with peripheral Treg reconstitution. These observations provide strong evidence that endogenous CD4(+) Tregs have a negative impact on cancer therapy, and suggest that strategies reducing Treg levels may provide clinical benefit to cancer patients. All 5 clinical trials are registered at www.clinicaltrials.gov as NCT00001832, NCT00096382, NCT00335127, NCT00509496, and NCT00513604.
    Blood 05/2012; 119(24):5688-96. · 9.78 Impact Factor
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    ABSTRACT: ABO blood type antigens are expressed not only on human red blood cells, but also throughout the gastrointestinal tract and in normal pancreatic tissue. Previous studies have identified an association between ABO blood type and various malignancies. We analyzed the association of ABO blood type with pancreatic neuroendocrine tumors (PNETs) in a high-risk cohort of patients with Von Hippel-Lindau (VHL) syndrome. A retrospective review was performed of 798 patients with VHL syndrome. Blood type was confirmed for 181 patients. Fisher's exact test and Mehta's modification to Fisher's exact test were used to test for an association between ABO blood type and manifestations of VHL syndrome. We found a strong trend for association between O blood type and pancreatic disease manifestation in patients with VHL syndrome (P = 0.047). More importantly, there was a significant association of O blood type with solid pancreatic lesions consistent with PNETs (P = 0.0084). Patients with solid pancreatic lesions who met criteria for surgical resection at the National Institutes of Health also had a higher rate of O blood type than those who did not require surgery (P = 0.051). Our findings suggest an association between O blood type and pancreatic manifestation of disease in patients with VHL syndrome, especially for PNETs. Screening and surveillance approaches for pancreatic lesions in patients with VHL syndrome should also consider patient blood type. The possibility of A, B, H misexpression in PNETs should also be explored to determine whether the serologic association with disease translates into a relationship with tissue pathology.
    Annals of Surgical Oncology 02/2012; 19(6):2054-9. · 4.12 Impact Factor

Publication Stats

3k Citations
584.96 Total Impact Points

Institutions

  • 2005–2014
    • National Cancer Institute (USA)
      • • Center for Cancer Research
      • • Genetics Branch
      Maryland, United States
  • 2000–2013
    • National Institutes of Health
      • • Laboratory of Tumor Immunology and Biology
      • • Branch of Social and Behavioral Research
      • • Branch of Experimental Immunology
      Bethesda, MD, United States
  • 2012
    • National Institute of Mental Health (NIMH)
      • Laboratory of Molecular Biology
      Maryland, United States
  • 2011
    • National Institute of Standards and Technology
      Maryland, United States
  • 2001
    • Cancer Research and Biostatistics
      Seattle, Washington, United States