Citations

Abstract So far, therapeutic vaccination with allogeneic cancer cells has been only marginally effective. A reason for failure could stem from the fact that vaccine cells are usually cultured in air (pO2=20 kPa), while tumors in situ are often highly hypoxic. Hence, it is possible that vaccine cells expressed antigens differently than tumor cells in situ. We postulate that cells grown at low pO2 provide a better antigen match to tumors in situ and could be more effective vaccines. We tested the former hypothesis by comparing prostate cancer (CaP) cells propagated at pO2 = 2 kPa and 20 kPa. To identify potential tumor-associated antigens, we prepared CaP cell lysates, resolved them by 2D electrophoresis and immunoblotting using spontaneous antibodies from plasma derived from CaP patients and control subjects. Antibody-labeled spots were analyzed by MALDI-TOF mass spectrometry. Among identified molecules, we selected hypoxia-regulated HSP70 and hnRNP L and hypoxia-independent HSP60 and determined by ELISA the frequency of plasma samples reacting with these molecules two standard deviations above their reaction with normal sera. Frequency of HSP60-reactive plasma was 1/76 in healthy controls (HC; 1.3%), while it was 7/54 in CaP patients (13.0%; p<0.05). The corresponding values were 1/14 in colorectal cancer (7.1%), 1/10 in lung cancer (LC; 10.0%), 1/20 in renal cell carcinoma (5.0%) and 0/17 in rheumatoid arthritis (RA; 0%), not different from healthy controls. These data suggest that CaP patients develop humoral immunity to HSP60. Levels of autoantibodies to HSP70 in CaP patients (2/38, 5.3%) did not differ from HC (2/54, 3.7%) while they did differ from HC in LC (2/10, 20.0%) and RA (3/17, 17.7%). Similarly, frequency of autoantibodies to hnRNP L did no differ between HC (3/49, 6.1%) and CaP patients (2/38, 5.3%). Further, we evaluated the expression of hnRNP L protein in native CaP tissue by Western blot. In contrast to the levels of autoantibodies in plasma, hnRNP L antigen was present at twice the levels in CaP tissue (N=8) than in control benign prostate tissue (N=4; p<0.05). Overall, our results suggest that it is worthwhile to pursue evaluating of HSP60-specific autoantibodies as a CaP-associated marker. Currently, we are analyzing HSP60 and hnRNP L (hypoxia-regulated) protein and transcript expression by immunohistochemistry and PCR, respectively, in a large patient cohort. This approach could validate the use of hypoxia-sensitive molecules as effective prognostic biomarkers and help develop better therapy for CaP and, possibly, other tumors. Support: DOD PC094680 and PCF Creativity Award (both to CRG). Citation Format: Tangeng Ma, Abdelouahid Elkhattouti, Farhad Kosari, R. Jeffrey Karnes, John C. Cheville, George Vasmatzis, Stanimir Vuk-Pavlović, Christian R. Gomez. Hypoxia as a tool for identifying prostate cancer-associated antigens. [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 4056. doi:10.1158/1538-7445.AM2013-4056

Abstract Background: Hormone therapy (HT) may prevent colorectal cancer (CRC), but the molecular mechanisms have not been fully defined. Expression of estrogen receptor beta (ERβ) has been associated with CRC stage and survival and may influence HT-related prevention pathways. In this prospective cohort study, we examined HT-associated CRC risk by ERβ protein expression levels in the population-based Iowa Women's Health Study (IWHS). Methods: The IWHS recruited 41,836 randomly selected Iowa women, ages 55-69 years, with a valid driver's license at study entry (1986). Exposure variables were assessed at baseline, by self-report. Incident CRC cases were ascertained by annual linkage with the Iowa Cancer Registry. Archived, paraffin-embedded tissue specimens were collected from 732 CRC cases, diagnosed through 12/31/2002, for molecular epidemiology studies. HT was categorized as never, former, and current and with durations of <=5 years or >5 years. ERβ protein expression was determined by immunohistochemistry on tissue microarrays. For each tumor core, both staining intensity (0-3) and proportion of cells stained (0-5) were scored. These two scores were added to determine negative (0), low (1-5) or high (6-8) ERβ protein expression levels. Multivariate Cox regression models were fit to estimate relative risks (RRs) and 95% confidence intervals (CIs). Results: Complete HT and ERβ data were available from 484 CRC cases. Associations between HT and CRC subtypes defined by ERβ expression level are shown in the Table. Conclusions: Data from the IWHS cohort suggest that current and longer-duration HT exposure favorably influence the risk for ERβ-neg or ERβ-low CRC cases to a greater degree than ERβ-high CRC cases. Further investigation is required to confirm these observations, and to clarify the underlying mechanisms. ERβ Neg or Low ERβ High Hormone Therapy Person years Events, N RR* (95% CI) Events, N RR* (95% CI) Never 341377 128 1.00 (Ref.) 196 1.00 (Ref.) Ever 212696 62 0.74 (0.54,1.03) 98 0.82 (0.63,1.07) Former 151535 48 0.79 (0.56,1.12) 67 0.73 (0.54,0.99) Current 61161 14 0.60 (0.33,1.09) 31 1.11 (0.74,1.64) P-trend 0.05 0.52 Duration < = 5yrs 148704 47 0.84 (0.59,1.19) 68 0.80 (0.60,1.08) >5yrs 60064 14 0.5 (0.26,0.93) 28 0.89 (0.59,1.34) P-trend 0.03 0.25 Citation Format: Lori S. Tillmans, Robert A. Vierkant, Alice H. Wang, Charles F. Lynch, Kristin E. Anderson, Amy J. French, Robert W. Haile, John D. Potter, Susan L. Slager, Thomas C. Smyrk, Stephen N. Thibodeau, James R. Cerhan, Paul J. Limburg. Hormone therapy and incident colorectal cancer risk by ER beta protein expression level in a population-based cohort of older women. [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 3652. doi:10.1158/1538-7445.AM2013-3652

Abstract Background. Transmembrane transport (GO:0055085) is the process whereby a solute/hormone/ion/iron is transported from one side of a membrane to the other. Disruption of these processes leads to defects in homeostasis which contributes to cancer risk. We hypothesized that germline single nucleotide polymorphisms (SNPs) in the cellular transport genes are associated with EOC risk and histopathology subtype. Methods. We genotyped 305 SNPs from 120 cellular transport related genes in 14,525 cases and 23,448 controls of European ancestry, 387 African, and 2,388 Asian ancestries from 43 studies in the Ovarian Cancer Association Consortium (OCAC). A custom Illumina iSelect designed for the Collaborative Oncological Gene-environment Study (COGS) was used. For women of European ancestry, both invasive cancers combined and the four main histological subtypes (serous (n=8,369), mucinous (n=943), endometroid (n=2,067) and clear cell (n=1,024) carcinoma) were analyzed, while for women of African and Asian ancestry only the serous subtype was analyzed adjusting for study site and first 5 principal components. Odds ratios and 95% confidence intervals were calculated using unconditional logistic regression. We fitted a log-additive genetic model. Results. In women of European ancestry, the strongest evidence of an association for all invasive EOCs was the iron transport gene, HEPH rs17216603 (OR=0.85, 95%CI=0.78-0.93, P=2.8x10−4), which was also the most significant association for serous histological subtype (OR=0.81, 95%CI=0.73-0.91, P=2.0x10−4). For endometrioid EOC, the strongest association was observed in the glucuronidation gene, UGT1A5 rs11563251 (OR=0.82, 95%CI=0.73-0.92, P=6.6x10−4). For clear cell and mucinous EOC, the thyroid hormone transport protein, SERPINA7 rs1804495 showed the strongest associations (OR=1.06, 95%CI=1.06-1.38, P=0.0041) and (OR=0.85, 95%CI=0.73-0.98, P=0.0407), respectively. For women of African ancestry, the strongest association for serous EOC was the glutathione conjugation gene, MGST rs6488840 (OR=0.55, 95%CI=0.37-0.82, P=0.0035). This SNP was not significant in women of European or Asian ancestry. In women of Asian ancestry, the HEPH rs17216603 (OR=1.45, 95%CI=1.15-1.83, P=0.0019) demonstrated the strongest association, although the directionality of risk was reversed compared to European women. Conclusions. Our results suggest that variation in transmembrane transport genes may influence EOC risk and histopathologic subtype in women of European, African and Asian ancestries, highlighting the differences in the disease etiology across populations. Additional epidemiological and functional studies are warranted to elucidate translational and clinical utility of these associations. Citation Format: Ganna Chornokur, Jonathan Tyrer, Hui-Yi Lin, Gang Han, Xiaotao Qu, Chen Zhihua, Ya-Yu Tsai, Ellen L. Goode, Julie M. Cunningham, Edwin Iversen, Susan J. Ramus, Andrew Berchuk, Joellen M. Schildkraut, Alvaro Monteiro, Simon A. Gayther, Steven A. Narod, Paul Pharoah, Thomas A. Sellers, Catherine M. Phelan. Variation in transmembrane transport genes influence epithelial ovarian cancer risk and histopathologic subtype. [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 3644. doi:10.1158/1538-7445.AM2013-3644

Abstract Background: Endometrial cancers account for over 46,000 cases and 8,100 deaths annually in the U.S. Endometrial cancers that are confined to the uterus portend an excellent prognosis, suggesting that development of early detection methods for these tumors could reduce mortality. To identify and validate markers with potential utility in early detection of endometrial cancers, we compared DNA methylation profiling data for endometrial cancer tissues collected in a population-based epidemiological study and a comparison set of benign endometrial tissues, and replicated promising candidates in a separate clinical study. Methods: We used the Illumina Golden Gate platform to profile DNA methylation of CpGs at 1536 sites (807 genes) using fixed tissues from 148 endometrial cancers included in the population-based Polish Endometrial Cancer Study (cases) and 23 benign endometrial tissues collected at Magee Women's Hospital (controls). Tissue cores (1.0-mm) removed from target-rich areas of blocks were used for DNA extraction, bisulfite treatment and profiling. We replicated top candidate markers by applying pyrosequencing assays to endometrial brushings performed prior to hysterectomy among 38 women with endometrial cancer and 37 with benign gynecological diseases treated at the Mayo Clinic and calculated odds ratios comparing the highest tertile of methylation values in controls for each marker with middle and low tertiles. In addition, we assessed discrimination across the whole range of cutoffs using Receiver Operator Characteristics (ROC) curves. Results: Methylation profiling identified 114 CpG sites with differential methylation levels between cases and controls (P≤10-7). Eight genes (ADCYAP1, ASCL2, HS3ST2, HTR1B, MME, NPY, and SOX1) which showed large case-control differences in methylation levels (≥ 0.4), and low values in controls (<0.2) were chosen for replication by pyrosequencing in pre-hysterectomy patients. In the replication study, higher methylation levels were found for 7 of 8 genes in endometrial brush samples from women with cancer as compared to women without cancer. In the replication study, odds ratios for association of methylation markers with endometrial cancer ranged from 3.6 (95%-CI: 1.35-9.47) for HTR1B to 10.9 (95%-CI: 3.23-36.91) for ASCL2. Discrimination of cases and controls was best for ADCYAP1 (area under ROC curve=0.89; 95% CI: 0.80-0.97), CDH13 (0.87; 95% CI: 0.80-0.97), and MME (0.87; 95% CI: 0.78-0.97). Conclusions: Analysis of DNA methylation markers in endometrial brushings is strongly associated with prevalent endometrial cancer at hysterectomy. Development and validation of a robust early detection marker panel for endometrial cancers, including non-endometrioid cancers and precursor lesions is ongoing. Citation Format: Nicolas A. Wentzensen, Jamie Bakkum, Keith Killian, Viji Shridhar, Lisa Adams, Richard Guido, Lori D'Ambrosio, Patricia Luhn, Joshua Sampson, Hannah Yang, Louise Brinton, Jolanta Lissowska, Karl Podratz, Mark Sherman. Discovery and validation of methylation markers for early detection of endometrial cancer. [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 3477. doi:10.1158/1538-7445.AM2013-3477

Abstract Background: Ovarian cancer (OC) is the leading cause of gynecologic cancer death in the United States. Survival in advanced OC is highly variable and is impacted by the endogenous anti-tumor immune response. Toll-like receptors (TLR) on tumor-infiltrating leukocytes can modulate anti-OC immunity. Heparan sulfate (HS) is an oligosaccharide component of the extracellular matrix that, when released, binds and triggers TLR-4 to induce production of multiple cytokines; HS is liberated from the extracellular matrix by heparanase, which is overexpressed by many ovarian cancers. We therefore explored the association between plasma levels of HS, heparanase, proinflammatory and immunosuppressive cytokines, and survival in patients with advanced OC. Methods: We designed a two stage cohort study of plasma biomarkers in ovarian cancer patients. For the pilot stage, we enrolled 100 patients with advanced OC (AJCC Stage III and IV), 50 patients with early stage OC (Stage I and II), and 50 patients with benign surgical conditions from the Mayo Ovarian SPORE Biospecimens Core. For the expansion stage, 257 patients with advanced OC were enrolled. Presurgical plasma samples were assayed for HS, heparanase, and multiple cytokines by ELISA and electrochemiluminescence. Differences in plasma levels between benign, early, and advanced OC patient groups were assessed using plate-adjusted linear models. Associations between plasma levels of HS and heparanase with overall survival in advanced OC patients were assessed by Cox proportional hazards models using a log2 transformation; total effects across stages were estimated using a meta-analysis approach. Results: In the pilot cohort, soluble HS levels were similar in control (mean +/ STD: 88.26 +/- 32.23), early stage (93.91 +/- 37.77), and advanced OC (93.55 +/- 40.44), with similar values observed in the expansion cohort (129.29 +/- 95.64). There was no correlation between heparanase and HS levels. Higher levels of HS were associated with improved overall survival (log2 HR = 0.62, p = 0.042; HR = 0.84, p = 0.014; HR = 0.82, 95% CI: 0.71-0.93, p = 0.003 for the pilot, expansion, and combined sets, respectively). There was no association between heparanase levels and overall survival (all p > 0.45). Conclusions: Neither soluble HS nor heparanase were elevated in presurgical OC patients relative to controls; however, higher levels of HS were associated with improved survival in patients with advanced OC. These results suggest that HS may play a key role in modulating the innate immune response to OC. Citation Format: Matthew S. Block, Matthew J. Maurer, Krista M. Goergen, Courtney L. Erskine, Marshall D. Behrens, Kimberly R. Kalli, Keith L. Knutson. Higher plasma levels of heparan sulfate are associated with improved survival of patients with advanced ovarian cancer. [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 3476. doi:10.1158/1538-7445.AM2013-3476

Abstract There is a significant unmet medical need to develop more effective treatments for cancers of the central and peripheral nervous systems. Glioblastoma multiforme (GBM) is the most common form of brain cancer, and successful long-term treatment has not been realized. Neuroblastomas (NB) arise in the sympathetic nervous system and are the most common extracranial solid tumor of childhood. Survival of children with disseminated, high-risk NB tumors is less than 50%, even with intensive multimodal treatment. To improve treatment outcome, inhibition of murine double minute 2 (MDM2) function in the context of front-line therapy is being explored. MDM2 is a multi-functional protein that plays a critical role in controlling cell growth and migration. MDM2 is a negative regulator of p53 and p73 and, under low stress conditions, sequesters them in the cytoplasm. However, inhibition of MDM2 interactions with p53 and p73 by the MDM2 antagonist nutlin3a can lead to activation of p53/p73-mediated cell-death in tumor cells. The objective of the present study was to evaluate the extent to which blockade of MDM2-p53/p73 interactions by nutlin3a, alone or in combination with front-line therapies, could augment cell death in GBM and NB cells with a variety of molecular profiles. Using the median effect model, we found that temozolomide (TMZ) and nutlin3a were synergistic in increasing cell death in wtp53 U87 and U373 but were predominantly additive in mtp53 U118 cells. Primary patient GBM cells were typically resistant to TMZ relative to established cell lines. However, resistance to TMZ was decreased in the presence of nutlin3a. Further, TMZ and nutlin3a were synergistic in primary GBM10 and GBM43 but not in recurrent primary IU-GBM16, IU-GBM23, IU-GBM27, and IU-GBM32 cells. Moreover, in NB cells with wtp53, nutlin3a and cisplatin were synergistic in MYCN nonamplified SK-N-SH and additive in MYCN amplified IMR5. In mtp53 NB cells, nutlin3a and cisplatin were synergistic in MYCN nonamplified SK-N-FI as well as in MYCN amplified SK-N-DZ. Nutlin3a alone produced dose-related increases in cell death of all GBM and NB cell lines irrespective of p53 status, suggesting that p53-independent mechanisms play a role in inhibition of cell growth produced by blockade of MDM2-mediated signaling. Consistent with this hypothesis, nutlin3a increased p73 protein levels in mtp53 GBM43 cells that were exposed to TMZ. Inhibition of MDM2 function also inhibited repair of TMZ-mediated DNA damage in GBM. In comet assays, nutlin3a+TMZ decreased DNA repair relative to TMZ alone in wtp53 U87 and GBM10 and in mtp53 GBM43 cells. The present results demonstrate that MDM2 is a valid therapeutic target in GBM and NB cells with varying genetic profiles. In conclusion, inhibition of MDM2 signaling by nutlin3a is generally synergistic to additive in combination with front-line chemotherapeutics used to treat cancers of the central and peripheral nervous systems. Citation Format: Harlan E. Shannon, Haiyan Wang, Shanbao Cai, Wei Michael Liu, Lawrence M. Gelbert, Aaron A. Cohen-Gadol, Jann N. Sarkaria, Lindsey D. Mayo, Karen E. Pollok. MDM2 as a therapeutic target: improving upon front-line chemotherapy for nervous system tumors. [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 3435. doi:10.1158/1538-7445.AM2013-3435

Abstract Wee1 is a key regulator of both G2/M transition and DNA replication fork stability. In this study, the efficacy of the Wee1 inhibitor MK1775 was evaluated in the Mayo primary glioblastoma multiforme (GBM) xenograft model. Based on western blot expression of Wee1, GBM22, GBM12 and GBM6 were selected for study based on low, intermediate and high-level expression, respectively. Wee1-mediated phosphorylation of Y15-Cdc2 was robustly suppressed in vitro in both GBM22 and GBM6 at 300 nM MK1775. At this concentration, MK1775 had marked anti-proliferative effects on GBM22 with 80±2.5% suppression of absorbance in a CyQUANT cell proliferation assay, while similar treatment of GBM6 had minimal effect on growth (26±21% suppression of absorbance). In a similar primary neurosphere formation assay, 300 nM completely inhibited neurosphere formation in GBM22 and GBM12, while having no effect on GBM6 neurosphere formation. Consistent with the cytotoxicity data, single agent treatment of GBM22 with MK1775 resulted in a marked S-phase arrest 24 hours after treatment (60% vs. 40% cells in S with MK1775 vs. control, respectively) and subsequent accumulation of cells in G2/M 48 hours after treatment (95% vs. 9.5%, respectively). In contrast, relatively minimal cell cycle perturbations were observed with MK1775 in GBM6 (24 hour S-phase accumulation 27% vs. 21%, respectively). Combination studies with MK1775 and temozolomide (TMZ) in a neurosphere formation assay demonstrated enhancement of treatment benefit only in GBM22 and GBM12 but not GBM6 (relative neurosphere numbers for TMZ, MK1775, or combined treatment compared to untreated were 34%, 16% and 7%, respectively for GBM22, 41%, 95% and 15%, respectively, for GBM12; while the same combination had no effect on GBM6 neurosphere formation). In anticipation of evaluating treatment efficacy in animal models, pharmacokinetic modeling of MK1775 brain delivery was performed in nude mice. Following a single MK1775 dose of 50 mg/kg, time to maximum blood concentration was 1.0 hours, AUC was 29.8 microM·h, and Cmax was 7.8 microM in whole blood and 0.24 microM in brain parenchyma. To evaluate whether limitations in brain delivery affected efficacy, parallel in vivo GBM12 heterotopic and orthotopic xenograft efficacy studies were performed with a 5 day dosing regimen of TMZ and MK1775 repeated every 28 days for 3 cycles. In the orthotopic model, MK1775 provided no survival benefit with median survival being 16, 15, 88 and 92 days for placebo, MK1775 alone, TMZ alone, or MK1775 + TMZ treatment, respectively. In contrast, there is some suggestion of MK1775 efficacy in the flank tumor model with median time to reach 1000 mm3 being 45, 56, 101 and 112 days, respectively. Collectively, these data suggest that despite promising in vitro activity for MK1775, limited drug delivery into the brain may reduce the efficacy of MK1775 therapy in an orthotopic GBM xenograft model. Citation Format: Jenny Pokorny, Vincenzo Pucci, Stuart Shumway, Bennett Ma, Katrina Bakken, Mark Schroeder, Brett Carlson, Jann N. Sarkaria. Pre-clinical investigation of the Wee1 inhibitor, MK1775, in glioblastoma multiforme. [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 3240. doi:10.1158/1538-7445.AM2013-3240

Abstract Pancreatic cancer is the 10th most common cancer and 4th most common cause of cancer mortality in the United States. A genome wide association study has revealed pancreatic cancer susceptibility loci on chromosomes 13q22.1, 1q32.1 and 5p15.33. The chr13q22.1 region contains the most significant of all risk SNPs, rs9543325, (P= 3.27 x 10−11) which is located in a gene desert. The nearest genes are KLF5, KLF12, PIBF1, DIS3 and BORA, which range in distance from 265kb to 586kb, respectively, from the most significant variants. Given the high linkage disequilibrium across this risk locus, there are many candidate functional variants to consider. Imputation in the region did not improve the signal but gave a set of highly correlated SNPs which likely includes the functional variant(s). In an effort to identify the functional variant(s) we performed eQTL analyses to test the association between the genotypes of these candidate SNPs and expression of nearby genes. Among 100 normal pancreatic tissue samples, DIS3 showed the strongest association with SNPs in our risk locus (P-values as low as 0.0004). Mutations in DIS3 have been identified in acute myeloid leukemia and multiple myeloma, and its expression has been correlated with metastatic potential in colorectal cancer, suggesting this gene could be important in pancreatic cancer biology. Chromosome Conformation Capture (3C) was performed to test for physical interactions between the risk locus and nearby genes. This assay confirmed the three dimensional proximity of the risk locus and DIS3 promoter. Sub-regions of the risk locus were then cloned upstream of a minimal promoter controlling luciferase expression to assay for potential allele specific enhancer/silencer activity. This assay revealed a sub-region downstream of rs9543325 that causes allele-specific silencing. These results suggest that a sub-region of the chr13q22.1 risk locus has allele-specific effects on DIS3 expression, which may have implications in the susceptibility to pancreatic cancer. Citation Format: Jason Hoskins, Abdisamad Ibrahim, Jinping Jia, Irene Collins, Hemang Parikh, Gloria M. Petersen, Laufey Amundadottir. Functional analysis of the chr13q22.1 pancreatic cancer risk locus suggests allele-specific effects on DIS3 expression. [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 3137. doi:10.1158/1538-7445.AM2013-3137

Abstract Background: Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) is the most common adult leukemia in the United States. Prior studies in Olmsted County, Minnesota, showed a CLL age and sex adjusted incidence rate of 6.6 per 100,000 during 1985-89. Subsequently, the definition of CLL is now based on the 2008 International Workshop on CLL (IWCLL) Guidelines. Individuals having a CLL immunophenotype by flow cytometry are classified as CLL if the absolute B-cell count (ABC) is >5 x 109/L or classified as monoclonal B-cell lymphocytosis (MBL) if ABC is <5 x 109/L. To assess the impact of these changes on the incidence of CLL and clinically discovered MBL, we conducted an incidence study in Olmsted County for the years 2000-2010. Methods Using diagnostic indexes available through the Rochester Epidemiology Project and the Mayo CLL database, we identified all CLL and clinically identified MBL cases from 2000-2010. Incidence rates and demographics were compared between the older National Cancer Institute-Working Groups 1996 guidelines (NCI-WG 96) defined as absolute lymphocyte count (ALC)> 5 x 109/L and the IWCLL 2008 guidelines defined as ABC > 5 x 109/L. Incidence rates were age and sex adjusted using the 2010 US white population. Time to treatment (TTT) survival analyses was from time of diagnosis to date of first treatment or last follow-up and Cox regression analysis was used. Results Using the NCI-WG 96 classification, there were 8 MBL cases and 115 CLLs in whom 61% were Rai stage 0, 34% were Rai stage 1-2, and 5% were Rai stage 3-4. Using the IWCLL 2008 classification, there were 44 MBL cases and 79 CLLs in whom 43% Rai stage 0, 49% were Rai stage 1-2 and 8% Rai stage 3-4. Median ALC at diagnosis was 8.1 x 109/L for CLL and 5.9 x 109/L for MBL. Median ABC count at diagnosis was 7.1 x 109/L for CLL and 2.8 x 109/L for MBL. The age and sex adjusted incidence rate (per 100,000) for CLL for 2000-2010 was 10.0 using NCI-WG 96 and 6.8 using IWCLL 2008. Rates for MBL were 0.66 using NCI-WG 96 and 3.5 using IWCLL 2008. The median TTT for CLL was 9.2 years using NCI-WG 96 and 6.5 years by IWCLL 2008. Discussion This study demonstrates that reclassification of CLL using the IWCLL 2008 guidelines decreases CLL incidence relative to the NCI-WG 96 criteria. For the first time, this population based study also establishes an incidence rate for clinically identified MBL. Approximately 50% of previously labeled Rai 0 CLL are now reclassified as MBL. Re-classification increases the percent of Rai stage 1-2 and decreases the percent of Rai 0 cases at diagnosis. Reclassification also substantially shortens the median TTT for newly diagnosed CLL cases classified by the 2008 criteria relative to the NCI-WG 96 criteria. In summary, the IWCLL 2008 reclassification has significant implications for incidence studies, staging, and prognosis of CLL and MBL. Citation Format: Aaron D. Norman, Timothy G. Call, Curtis A. Hanson, Neil E. Kay, Clive S. Zent, Wei Ding, James R. Cerhan, Sara J. Achenbach, Kari G. Rabe, Celine M. Vachon, Emily J. Hallberg, Tait D. Shanafelt, Susan L. Slager. Incidence of chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis in Olmsted county, 2000-2010: impact of the 2008 International Workshop on CLL Guidelines. [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 2287. doi:10.1158/1538-7445.AM2013-2287

Abstract Metformin is a bi-guanidine employed in treating Type II diabetes. Epidemiologic studies have suggested that diabetics receiving metformin vs thialidizones or insulin have a lower incidence of cancer. In addition, metformin decreases levels of AMPK and IGF1; encouraging its use in both cancer prevention and therapy settings. Most preclinical studies with metformin have employed cell culture or xenografts. We examined its efficacy in multiple in situ animal cancer models. The preventive effect of Metformin administered by gavage or in the diet, at roughly the human equivalent dose (HED), was determined in four standard animal models: (1) methylnitrosourea (MNU)-induced ER+ mammary cancers; (2) MMTV-Neu ER− mammary cancers; (3) hydroxybutyl(butyl)nitrosamine (OH-BBN) induced urinary bladder cancers; and (4) Min mouse model of intestinal tumorigenesis. In the MNU model, Metformin (150 or 50 mg/Kg BW/day) was ineffective as a preventive dose; decreasing neither tumor multiplicity nor latency. Furthermore, both doses increased final tumor weights in treated rats. PK studies at the higher dose of Metformin (150 mg/kg BW/day) showed serum levels slightly higher than humans taking 1.5 g per day. In the MMTV-Neu model, dietary metformin (1200 PPM in diet) decreased the latency of tumor development as well as slightly, but insignificantly, increasing the final tumor multiplicity. Metformin (1200 ppm in diet) in the Min mouse model marginally increased the multiplicity of intestinal adenomas. In contrast, the NSAID naproxen (400 ppm in diet) examined simultaneously in the min mouse strongly inhibited adenoma development. Metformin (150 mg/Kg BW/day) in the OH-BBN induced model of urinary bladder cancer failed to significantly reduce bladder cancers despite relatively high levels of Metformin in the urine. In the MNU model, when rats were placed on a high fat diet to induce a pre-diabetic state, we observed roughly a 20% decrease in tumor multiplicity in the metformin treated rats (P> 0.10). In contrast, tamoxifen and Targretin (an RXR agonist) that were used as positive controls were highly effective in rats on a high fat diet. Metformin didn't decrease tumorigenesis in these standard models, but actually increased tumor formation (incidence, multiplicity, weight) in three of the four models at their HED. These results should particularly discourage any large phase clinical trials in individuals without insulin resistance. The final study certainly raises the question whether the agent might be effective in animals that are diabetic or show insulin resistance Citation Format: Clinton J. Grubbs, Margie L. Clapper, Joel M. Reid, Vernon E. Steele, Ronald A. Lubet. Metformin promotes tumorigenesis in animal models of cancer prevention. [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 2273. doi:10.1158/1538-7445.AM2013-2273