Human T-lymphotropic virus type I proviral loads in patients with adult T-cell leukemia-lymphoma: Comparison between cutaneous type and other subtypes

Adult T-cell leukemia-lymphoma (ATL), characterized by various clinicopathological features, is divided into four clinical subtypes, namely, acute, lymphoma, chronic and smoldering types, and the treatment strategy differs according to the clinical subtype. The designation cutaneous type ATL has been proposed to describe a peculiar subgroup of smoldering type ATL in which the skin is predominantly affected. However, diagnostic criteria and prognostic factors for cutaneous type ATL remain to be determined. Therefore, we performed a retrospective study to obtain a precise method for subtype classification and to clearly define cutaneous type ATL. A total of 87 ATL patients (acute, n = 31; lymphoma, n = 6; chronic, n = 24; smoldering, n = 26) were enrolled. The human T-lymphotropic virus type I (HTLV-1) proviral load in peripheral blood and the serum soluble interleukin-2 receptor (sIL-2R) level were evaluated with respect to the clinical features of the different types of ATL. The HTLV-1 proviral load was significantly increased in the acute and chronic type and the serum sIL-2R level was increased in the acute and lymphoma type. The HTLV-1 proviral load was significantly lower in cutaneous than other smoldering types of ATL without skin lesions. The clinical findings of cutaneous type ATL were also different from other subtypes. These results indicate that, in combination, determination of the HTLV-1 proviral load and the serum sIL-2R level is useful for distinguishing among the different types of ATL, and strongly suggest that cutaneous type ATL is a distinct clinical entity.

Recent advances in the treatment of adult T-cell leukemia-lymphomas

Recent advances in treatment for adult T-cell leukemia-lymphoma (ATL) are reviewed herein. It is currently possible to select a therapeutic strategy for ATL and predict prognosis by classification of patients by clinical subtypes and clinicopathological factors. Although the overall survival (OS) of patients with ATL has increased marginally because of advances in chemotherapy, further prolongation of survival might be difficult with conventional chemotherapy alone. Promising results have been reported for antiviral therapy using zidovudine and interferon-α, and, indeed, antiviral therapy is currently the standard treatment for patients with ATL in western countries. Remarkably, the 5-year OS rates are 100% for both the smoldering-type and chronic-type ATL. Recently, treatments for ATL have included allogeneic hematopoietic stem cell transplantation and molecular targeted therapies. Furthermore, the anti-CCR4 monoclonal antibody mogamulizumab has been shown to have marked cytotoxic effects on ATL cells, especially in the leukemic type of ATL. In the lymphoma type of ATL, the response rate may be improved by combining mogamulizumab with chemotherapy. It should be recognized that prevention of infection from carriers of human T-cell leukemia virus type-I and transfer of the virus from mother to infant are crucial issues for the eradication of ATL.

Molecular characterization of chronic-type adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a human T-cell leukemia virus type-1-induced neoplasm with four clinical subtypes: acute, lymphoma, chronic, and smoldering. Although the chronic type is regarded as indolent ATL, about half of the cases progress to acute-type ATL. The molecular pathogenesis of acute transformation in chronic-type ATL is only partially understood. In an effort to determine the molecular pathogeneses of ATL, and especially the molecular mechanism of acute transformation, oligo-array comparative genomic hybridization and comprehensive gene expression profiling were applied to 27 and 35 cases of chronic and acute type ATL, respectively. The genomic profile of the chronic type was nearly identical to that of acute-type ATL, although more genomic alterations characteristic of acute-type ATL were observed. Among the genomic alterations frequently observed in acute-type ATL, the loss of CDKN2A, which is involved in cell-cycle deregulation, was especially characteristic of acute-type ATL compared with chronic-type ATL. Furthermore, we found that genomic alteration of CD58, which is implicated in escape from the immunosurveillance mechanism, is more frequently observed in acute-type ATL than in the chronic-type. Interestingly, the chronic-type cases with cell-cycle deregulation and disruption of immunosurveillance mechanism were associated with earlier progression to acute-type ATL. These findings suggested that cell-cycle deregulation and the immune escape mechanism play important roles in acute transformation of the chronic type and indicated that these alterations are good predictive markers for chronic-type ATL.

Downregulation of NDUFB6 due to 9p24.1-p13.3 loss is implicated in metastatic clear cell renal cell carcinoma

This study was conducted to clarify the genomic profiles of metastatic clear cell renal cell carcinomas (ccRCCs) and identify the genes responsible for development of metastasis. We analyzed the genomic profiles of 20 cases of primary ccRCC and their corresponding metastases using array-based comparative genomic hybridization, and identified 32 chromosomal regions in which gene copy number alterations were detected more frequently in metastases than in the primary tumors. Among these 32 regions, 9p24.1-p13.3 loss was the most statistically significant alteration. Furthermore, we found that patients with 9p24.1-p13.3 loss in primary tumors exhibited significantly lower rates of recurrence-free and cancer-specific survival, suggesting that 9p loss in the primary tumor is a potential biomarker predicting early recurrence of metastasis. Interestingly, the genomic profiles of primary tumors with 9p loss resembled those of their corresponding metastases, though 9p loss was accumulated in the metastases derived from the primary tumors without 9p loss. Comparison of the mRNA expression levels revealed that 2 of 58 genes located at 9p24.1-p13.3 were downregulated due to gene copy number loss in ccRCCs. An overexpression study of these two genes in ccRCC cell lines revealed that downregulation of NDUFB6 due to loss at 9p24.1-p13.3 may confer a growth advantage on metastatic ccRCC cells. These results were confirmed by analyzing the data of 405 cases of ccRCC obtained from The Cancer Genome Atlas (TCGA). On the basis of our present data, we propose that NDUFB6 is a possible tumor suppressor of metastatic ccRCCs.

Fasudil, a rho kinase inhibitor, limits motor neuron loss in experimental models of amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with no effective treatment. Fasudil hydrochloride (fasudil), a potent rho kinase (ROCK) inhibitor, is useful for the treatment of ischaemic diseases. In previous reports, fasudil improved pathology in mouse models of Alzheimer's disease and spinal muscular atrophy, but there is no evidence in that it can affect ALS. We therefore investigated its effects on experimental models of ALS.

EXPERIMENTAL APPROACH

In mice motor neuron (NSC34) cells, the neuroprotective effect of hydroxyfasudil (M3), an active metabolite of fasudil, and its mechanism were evaluated. Moreover, the effects of fasudil, 30 and 100 mg·kg(-1), administered via drinking water to mutant superoxide dismutase 1 (SOD1(G93A)) mice were tested by measuring motor performance, survival time and histological changes, and its mechanism investigated.

KEY RESULTS

M3 prevented motor neuron cell death induced by SOD1(G93A). Furthermore, M3 suppressed both the increase in ROCK activity and phosphorylated phosphatase and tensin homologue deleted on chromosome 10 (PTEN), and the reduction in phosphorylated Akt induced by SOD1(G93A). These effects of M3 were attenuated by treatment with a PI3K inhibitor (LY294002). Moreover, fasudil slowed disease progression, increased survival time and reduced motor neuron loss, in SOD1(G93A) mice. Fasudil also attenuated the increase in ROCK activity and PTEN, and the reduction in Akt in SOD1(G93A) mice.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that fasudil may be effective at suppressing motor neuron degeneration and symptom progression in ALS. Hence, fasudil may have potential as a therapeutic agent for ALS treatment.

Clonal heterogeneity of lymphoid malignancies correlates with poor prognosis

Clonal heterogeneity in lymphoid malignancies has been recently reported in adult T-cell lymphoma/leukemia, peripheral T-cell lymphoma, not otherwise specified, and mantle cell lymphoma. Our analysis was extended to other types of lymphoma including marginal zone lymphoma, follicular lymphoma and diffuse large B-cell lymphoma. To determine the presence of clonal heterogeneity, 332 cases were examined using array comparative genomic hybridization analysis. Results showed that incidence of clonal heterogeneity varied from 25% to 69% among different types of lymphoma. Survival analysis revealed that mantle cell lymphoma and diffuse large B-cell lymphoma with clonal heterogeneity showed significantly poorer prognosis, and that clonal heterogeneity was confirmed as an independent predictor of poor prognosis for both types of lymphoma. Interestingly, 8q24.1 (MYC) gain, 9p21.3 (CDKN2A/2B) loss and 17p13 (TP53, ATP1B2, SAT2, SHBG) loss were recurrent genomic lesions among various types of lymphoma with clonal heterogeneity, suggesting at least in part that alterations of these genes may play a role in clonal heterogeneity.

Array-comparative genomic hybridization profiling of immunohistochemical subgroups of diffuse large B-cell lymphoma shows distinct genomic alterations

Diffuse large B-cell lymphoma (DLBCL) displays striking heterogeneity at the clinical, genetic and molecular levels. Subtypes include germinal center B-cell-like (GCB) DLBCL and activated B-cell-like (ABC) DLBCL, according to microarray analysis, and germinal center type or non-germinal center type by immunohistochemistry. Although some reports have described genomic aberrations based upon microarray classification system, genomic aberrations based upon immunohistochemical classifications have rarely been reported. The present study aimed to ascertain the relationship between genomic aberrations and subtypes identified by immunohistochemistry, and to study the pathogenetic character of Chinese DLBCL. We conducted immunohistochemistry using antibodies against CD10, BCL6 and MUM1 in 59 samples of DLBCL from Chinese patients, and then performed microarray-based comparative genomic hybridization for each case. Characteristic genomic differences were found between GCB and non-GCB DLBCL from the array data. The GCB type was characterized by more gains at 7q (7q22.1, P < 0.05) and losses at 16q (P ≤ 0.05), while the non-GCB type was characterized by gains at 11q24.3 and 3q13.2 (P < 0.05). We found completely different mutations in BCL6+ and BCL6− non-GCB type DLBCL, whereby the BCL6− group had a higher number of gains at 1q and a loss at 14q32.13 (P ≤ 0.005), while the BCL6+ group showed a higher number of gains at 14q23.1 (P = 0.15) and losses at 6q (P = 0.07). The BCL6− group had a higher frequency of genomic imbalances compared to the BCL6+ group. In conclusion, the BCL6+ and BCL6− non-GCB type of DLBCL appear to have different mechanisms of pathogenesis.

Gene expression profiling of Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly reveals alterations of characteristic oncogenetic pathways

Epstein–Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of the elderly (EBV[+]DLBCL-E) is classified as a subtype of DLBCL. Until now, its molecular pathogenesis has remained unknown. To identify pathways characteristic of EBV(+)DLBCL-E, gene expression profiling of five EBV(+)DLBCL-E and seven EBV-negative DLBCL (EBV[−]DLBCL) cases was undertaken using human oligonucleotide microarray analysis. Gene set enrichment analysis and gene ontology analysis showed that gene sets of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) and nuclear factor kappa B (NF-κB) pathways were enriched in EBV(+)DLBCL-E cases. To confirm the results of the expression profiles, in vitro analysis was performed. Expression profiling analysis showed that high activation of the JAK-STAT and NF-κB pathways was induced by EBV infection into DLBCL cell lines. Activation of the NF-κB pathway was confirmed in EBV-infected cell lines using an electrophoretic mobility shift assay. Western blot analysis revealed an increased protein expression level of phosphorylated signal transducer and activator of transcription 3 (STAT3) in an EBV-infected cell line. Protein expression of phosphorylated STAT3 was frequently observed in lymphoma cells of EBV(+)DLBCL-E clinical samples using immunohistochemistry (EBV[+]DLBCL-E: 80.0% [n = 20/25] versus EBV[−]DLBCL: 38.9% [n = 14/36]; P = 0.001). The results of the present study suggest that activation of the JAK-STAT and NF-κB pathways was characteristic of EBV(+)DLBCL-E, which may reflect the nature of EBV-positive tumor cells. Targeting these pathways as therapies might improve clinical outcomes of EBV(+)DLBCL-E.

SegAnnDB: interactive Web-based genomic segmentation

MOTIVATION

DNA copy number profiles characterize regions of chromosome gains, losses and breakpoints in tumor genomes. Although many models have been proposed to detect these alterations, it is not clear which model is appropriate before visual inspection the signal, noise and models for a particular profile.

RESULTS

We propose SegAnnDB, a Web-based computer vision system for genomic segmentation: first, visually inspect the profiles and manually annotate altered regions, then SegAnnDB determines the precise alteration locations using a mathematical model of the data and annotations. SegAnnDB facilitates collaboration between biologists and bioinformaticians, and uses the University of California, Santa Cruz genome browser to visualize copy number alterations alongside known genes.

AVAILABILITY AND IMPLEMENTATION

The breakpoints project on INRIA GForge hosts the source code, an Amazon Machine Image can be launched and a demonstration Web site is http://bioviz.rocq.inria.fr.

Clinical significance of sIL-2R levels in B-cell lymphomas

Elevated soluble interleukin-2 receptor (sIL-2R) in sera is observed in patients with malignant lymphoma (ML). Therefore, sIL-2R is commonly used as a diagnostic and prognostic marker for ML, but the mechanisms responsible for the increase in sIL-2R levels in patients with B-cell lymphomas have not yet been elucidated. We first hypothesized that lymphoma cells expressing IL-2R and some proteinases such as matrix metalloproteinases (MMPs) in the tumor microenvironment can give rise to increased sIL-2R in sera. However, flow cytometric studies revealed that few lymphoma cells expressed IL-2R α chain (CD25) in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), and most CD25-expressing cells in the tumor were T-cells. Distinct correlations between CD25 expression on B-lymphoma cells and sIL-2R levels were not observed. We then confirmed that MMP-9 plays an important role in producing sIL-2R in functional studies. Immunohistochemical (IHC) analysis also revealed that MMP-9 is mainly derived from tumor-associated macrophages (TAMs). We therefore evaluated the number of CD68 and CD163 positive macrophages in the tumor microenvironment using IHC analysis. A positive correlation between the levels of sIL-2R in sera and the numbers of CD68 positive macrophages in the tumor microenvironment was confirmed in FL and extranodal DLBCL. These results may be useful in understanding the pathophysiology of B-cell lymphomas.

Abstract A30: Dysregulation of BMI1 and microRNA-16 collaborate to enhance an anti-apoptotic potential in the side population of refractory mantle cell lymphoma

The proto-oncogene BMI1 and its product, Bmi1, is overexpressed in various types of tumors, particularly in aggressive tumors and tumors resistant to conventional chemotherapy. BMI1/Bmi1 is also crucially involved in cancer-initiating cell maintenance, and is recurrently upregulated in mantle cell lymphoma (MCL), especially aggressive variants. Recently, side population (SP) cells were shown to exhibit tumor-initiating characteristics in various types of tumors. In this study, we show that recurrent MCL cases significantly exhibit upregulation of BMI1/Bmi1. We further demonstrate that clonogenic MCL SP shows such tumor-initiating characteristics as high tumorigenicity and self-renewal capability, and that BMI1 was upregulated in the SP from recurrent MCL cases and MCL cell lines. On screening for upstream regulators of BMI1, we found that expression of microRNA-16 (miR-16) was downregulated in MCL SP cells by regulating Bmi1 in the SPs, leading to reductions in tumor size following lymphoma xenografts. Moreover, to investigate downstream targets of BMI1 in MCL, we performed cross-linking/chromatin immunoprecipitation assay against MCL cell lines and demonstrated that Bmi1 directly regulated pro-apoptotic genes such as BCL2L11/Bim and PMAIP1/Noxa, leading to enhance anti-apoptotic potential of MCL. Finally, we found that a proteasome inhibitor bortezomib, which has been recently used for relapsed MCL, effectively induced apoptosis among MCL cells while reducing expression of Bmi1 and increasing miR-16 in MCL SP. These results suggest that upregulation of BMI1 and downregulation of miR-16 in MCL SP has a key role in the disease's progression by reducing MCL cell apoptosis. Our results provide important new insight into the pathogenesis of MCL and strongly suggest that targeting BMI1/Bmi1 might be an effective approach to treating MCL, particularly refractory and recurrent cases.

Citation Format: Akihiro Kitadate, Kazuaki Teshima, Kouichi Ohshima, Masao Seto, Kenichi Sawada, Hiroyuki Tagawa. Dysregulation of BMI1 and microRNA-16 collaborate to enhance an anti-apoptotic potential in the side population of refractory mantle cell lymphoma. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr A30.

Functionally deregulated AML1/RUNX1 cooperates with BCR-ABL to induce a blastic phase-like phenotype of chronic myelogenous leukemia in mice

Patients in the chronic phase (CP) of chronic myelogenous leukemia (CML) have been treated successfully following the advent of ABL kinase inhibitors, but once they progress to the blast crisis (BC) phase the prognosis becomes dismal. Although mechanisms underlying the progression are largely unknown, recent studies revealed the presence of alterations of key molecules for hematopoiesis, such as AML1/RUNX1. Our analysis of 13 BC cases revealed that three cases had AML1 mutations and the transcript levels of wild-type (wt.) AML1 were elevated in BC compared with CP. Functional analysis of representative AML1 mutants using mouse hematopoietic cells revealed the possible contribution of some, but not all, mutants for the BC-phenotype. Specifically, K83Q and R139G, but neither R80C nor D171N mutants, conferred upon BCR-ABL-expressing cells a growth advantage over BCR-ABL-alone control cells in cytokine-free culture, and the cells thus grown killed mice upon intravenous transfer. Unexpectedly, wt.AML1 behaved similarly to K83Q and R139G mutants. In a bone marrow transplantation assay, K83Q and wt.AML1s induced the emergence of blast-like cells. The overall findings suggest the roles of altered functions of AML1 imposed by some, but not all, mutants, and the elevated expression of wt.AML1 for the disease progression of CML.

Array CGH reveals clonal evolution of adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is the neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1). We performed oligoarray comparative genomic hybridization (CGH) against paired samples comprising peripheral blood (PB) and lymph node (LN) samples from patients with acute-type ATLL. Results disproved the established theory that true monoclonal proliferation, such as identical clonal expansion in all respects, occurred in acute-type ATLL, and our findings revealed that acute-type ATLL contains multiple subclones with differing genomic aberrations. Oligoarray CGH technology has been developed not only for high-resolution application but also for use in various analyses. Our original analysis is a method of identifying two or more clones with different chromosomal aberrations in one sample. Herein, we describe the analysis and clonal evolution of acute-type ATLL.

TEL (ETV6)-AML1 (RUNX1) initiates self-renewing fetal pro-B cells in association with a transcriptional program shared with embryonic stem cells in mice

The initial steps involved in the pathogenesis of acute leukemia are poorly understood. The TEL-AML1 fusion gene usually arises before birth, producing a persistent and covert preleukemic clone that may convert to precursor B cell leukemia following the accumulation of secondary genetic "hits." Here, we show that TEL-AML1 can induce persistent self-renewing pro-B cells in mice. TEL-AML1+ cells nevertheless differentiate terminally in the long term, providing a "window" period that may allow secondary genetic hits to accumulate and lead to leukemia. TEL-AML1-mediated self-renewal is associated with a transcriptional program shared with embryonic stem cells (ESCs), within which Mybl2, Tgif2, Pim2, and Hmgb3 are critical and sufficient components to establish self-renewing pro-B cells. We further show that TEL-AML1 increases the number of leukemia-initiating cells that are generated in collaboration with additional genetic hits, thus providing an overall basis for the development of novel therapeutic and preventive measures targeting the TEL-AML1-associated transcriptional program.

Dysregulation of BMI1 and microRNA-16 collaborate to enhance an anti-apoptotic potential in the side population of refractory mantle cell lymphoma

The proto-oncogene BMI1 and its product, Bmi1, is overexpressed in various types of tumors, particularly in aggressive tumors and tumors resistant to conventional chemotherapy. BMI1/Bmi1 is also crucially involved in cancer-initiating cell maintenance, and is recurrently upregulated in mantle cell lymphoma (MCL), especially aggressive variants. Recently, side population (SP) cells were shown to exhibit tumor-initiating characteristics in various types of tumors. In this study, we show that recurrent MCL cases significantly exhibit upregulation of BMI1/Bmi1. We further demonstrate that clonogenic MCL SP shows such tumor-initiating characteristics as high tumorigenicity and self-renewal capability, and that BMI1 was upregulated in the SP from recurrent MCL cases and MCL cell lines. On screening for upstream regulators of BMI1, we found that expression of microRNA-16 (miR-16) was downregulated in MCL SP cells by regulating Bmi1 in the SPs, leading to reductions in tumor size following lymphoma xenografts. Moreover, to investigate downstream targets of BMI1 in MCL, we performed cross-linking/chromatin immunoprecipitation assay against MCL cell lines and demonstrated that Bmi1 directly regulated pro-apoptotic genes such as BCL2L11/Bim and PMAIP1/Noxa, leading to enhance anti-apoptotic potential of MCL. Finally, we found that a proteasome inhibitor bortezomib, which has been recently used for relapsed MCL, effectively induced apoptosis among MCL cells while reducing expression of Bmi1 and increasing miR-16 in MCL SP. These results suggest that upregulation of BMI1 and downregulation of miR-16 in MCL SP has a key role in the disease's progression by reducing MCL cell apoptosis. Our results provide important new insight into the pathogenesis of MCL and strongly suggest that targeting BMI1/Bmi1 might be an effective approach to treating MCL, particularly refractory and recurrent cases.

Abstract 2014: Gene expression profiling identifies characteristic oncogenetic pathways in age-related Epstein-Barr virus (EBV)-positive B-cell lymphoproliferative disorders

Age-related EBV-associated B-cell lymphoproliferative disorder (AR-EBVLPD) is newly classified as a subtype of diffuse large cell lymphoma (DLBCL) according to the WHO classification. AR-EBVLPD cases have poor prognosis compared to that of EBV-negative DLBCL patients. Until now, its molecular pathogenesis remains largely unknown. We investigated gene expression profiling to identify molecular genetic characterization of AR-EBVLPD. Total RNA was extracted from fresh-frozen tumor samples of five AR-EBVLPD and eight EBV-negative DLBCL cases. Expression profiling was studied using the Agilent 44K human oligonucleotide microarray. Genes highly expressed in AR-EBVLPD included inflammatory and immune-related genes. Gene set enrichment analysis and gene ontology analysis showed that gene sets of the JAK-STAT and NF-kB pathways were enriched in AR-EBVLPD cases. In vitro analysis showed that high activation of JAK-STAT and NF-kB pathways was induced by EBV infection into DLBCL cell lines. The immunoprecipitation assay confirmed that the NF-kB pathway was activated in EBV-infected cell lines compared to EBV-naïve cell lines. The protein expression level of phosphorylated STAT3 increased in an EBV-infected cell line according to western blot analysis. A total of 61 patients (25 AR-EBVLPD and 36 EBV-negative DLBCL) were analyzed immunohistochemically for pSTAT3. Protein expression of phospho-STAT3 was frequently observed in lymphoma cells of AR-EBVLPD clinical samples using immunohistochemistry [AR-EBVLPD: (80.0%, n=20/25) vs. EBV-negative DLBCL: (38.9%, n=22/36), p=0.001]. These results suggested that STAT3 and NF-kB activation was characteristic of AR-EBVLPD, which may reflect the nature of EBV-positive tumor cells. Targeting these pathways as therapies might improve clinical outcomes of AR-EBVLPD.

Citation Format: Harumi Kato, Kazuhito Yamamoto, Kennosuke Karube, Jun Takizawa, Shinobu Tsuzuki, Yasushi Yatabe, Teru Kanda, Miyuki Katayama, Yukiyasu Ozawa, Kenji Ishitsuka, Masataka Okamoto, Tomohiro Kinoshita, Koichi Oshima, Shigeo Nakamura, Yasuo Morishima, Masao Seto. Gene expression profiling identifies characteristic oncogenetic pathways in age-related Epstein-Barr virus (EBV)-positive B-cell lymphoproliferative disorders. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2014. doi:10.1158/1538-7445.AM2013-2014