Citations

Abstract Patient derived xenografts (PDX) mouse models for many types of cancer have been developed recapitulating therapeutic responses in the patient for which the PDX model was derived. Essentially, live surgically resected or biopsy tumor tissues are directly implanted into immune incompetent mice to develop in vivo models to test therapies, follow tumor progression (gene mutations that occur with patient tumor progression do so in mice) or to better understand drug resistance. However, the use of PDX models also has its limitations and challenges. Our laboratory has attempted to develop PDX models in athymic nude mice for numerous cancer histotypes such as bladder, brain, breast, colon, kidney, lung, melanoma, ovarian, pancreas, sarcoma and thyroid. While melanoma and colon cancers have very high tumor take rates (73 - 100%), the other cancer histotypes do not (14 - 50%). We share our experience for each cancer histotype and the techniques used to enhance the success rates in athymic nude mice. We also address the other challenges that include expansion of tumors after cryopreservation and conversion of human tumors to mouse tumors and spontaneous lymphomas. We provide methods to test for human versus mouse content that include QPCR and immunohistochemistry Citation Format: Laura A. Marlow, James L. Miller, Brandy Edenfield, Adam C. Mathias, Louis K. Dawson, William F. Durham, Robert J. Mullin, Daniel L. Small, Aidan J. Synnott, Kevin Wu, John A. Copland. Methods for developing patient derived xenografts in athymic nude mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1453. doi:10.1158/1538-7445.AM2015-1453

Abstract We have developed the use of reovirus as a systemically delivered oncolytic agent in both pre-clinical models and in early Phase clinical trials. Reovirus has direct oncolytic activity against many human/murine tumor cells, partly because of disruption of the PKR-mediated anti-viral response in malignant cells. In addition however, we have shown that anti-tumor therapy is directly associated with immune activation by virus replication in tumors. The immune mechanisms of therapy include both innate immune activation against virally infected tumor cells, as well as the generation of adaptive anti tumor immune responses as a result of in vivo priming against tumor associated antigens released during that killing. Therefore, to exploit the immune components of reovirus anti-tumor therapy, we hypothesized that the combination of reovirus therapy with systemic checkpoint inhibition would augment therapeutic efficacy. To test the hypothesis, we used C57Bl/6 mice, an immune-competent murine model, with established subcutaneous (s.c.) B16 melanomas. In this model, intra-tumoral injection of reovirus into s.c. tumors generated moderate therapy. Provision of systemic anti-PD-1 antibody along with i.t. reovirus, significantly enhanced survival compared to i.t. reovirus alone (p<0.01) and led to >40% of mice being cured long term. Immune analysis suggested that the enhanced therapeutic benefit of reovirus plus checkpoint inhibition is contributed by at least two factors. First, blockade of PD-1 significantly enhanced the ability of NK cells to recognize (TNF-α secretion), and kill, reovirus-infected target tumor cells. Second, anti PD-1 antibody led to a significant reduction in Treg activity in reovirus-treated mice, with the overall effect of increasing the adaptive CD8+ anti-tumor T cell response. Furthermore, in vivo depletion studies demonstrated that NK cells had a dramatic effect in reducing the therapeutic efficacy of reovirus plus anti-PD-1 therapy. Overall, the results indicate that combination therapy of reovirus with PD-1 blockade confers significant survival benefit, by augmenting tumor-specific NK responses and specifically attenuating tumor-specific immunosuppression. These data also suggest that combination of PD-1 inhibition therapy with reovirus oncolytic/immunotherapy represents a readily translatable method to enhance the therapeutic efficacy. Citation Format: Karishma Rajani, Christopher Parrish, Kevin Shim, Liz Ilett, Fiona Errington-Mais, Jill Thompson, Tim Kottke, Rosa Maria-Diaz, Peter Selby, Hardev Pandha, Kevin Harrington, Alan Melcher, Matt Coffey, Shane Zaidi, Richard Vile. Combination therapy of reovirus and PD-1 blockade effectively establishes tumor control via innate and adaptive immune responses. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1360. doi:10.1158/1538-7445.AM2015-1360

Abstract About 25% of breast carcinomas are characterized by over-expression and/or amplification of the HER2 receptor, one of four members of the HER family of receptor tyrosine kinases. The strong correlation between HER2 levels/activity with more aggressive breast cancer disease, poor prognosis as well as resistance to chemo- and endocrine therapies made it a preferred target for anti-cancer therapy. However, current treatment strategies are only partially effective and the majority of breast cancer patients who initially respond favorably rapidly develop resistance to treatments for still not fully understood reasons. Thus, novel strategies/agents are in need. Structural analyses revealed that sub-domain III in the extracellular domain (ECD) of the HER family members is responsible for dimerization. We hypothesized that disrupting the dimerization loop in the HER2-ECD sub-domain III would ultimately convert HER2 to a non-functional receptor with diminished transforming capacity. To this end, we generated a series of HER2-ECD deletion mutants located in sub-domain III and assessed their oncogenic potential compared to the HER2-wild type (WT) after their expression in MCF10A cells. Importantly, a small deletion (16 amino acids) of the HER2 extracellular domain (named HER2Δ6) abolished its homo- and hetero-dimerization and profoundly affected HER2-catalyzed activation of the HER network. Moreover, this mutant was not able to transform MCF10 cells as it failed to promote anchorage-independent growth and interfered with the activation/Tyr phosphorylation of HER1, HER2 and HER3. Compared to HER2-WT-expressing cells, the HER2α6 mutant proved to be even more effective in inhibiting the oncogenic properties of the receptor than the current drugs of choice such as Trastuzumab and Pertuzumab alone or in combination. In addition, while expression of HER2-WT conferred resistance of MCF10A cells to Paclitaxel, the HER2Δ6 variant failed to do so. To determine the molecular mechanisms underlying this behavior, we assessed the mutant and WT expressing cells lines morphologically and biochemically and demonstrated that the HER2Δ6 is absent from the plasma membrane (PM) in MCF10A cells. Interestingly, we found that the mutant receptor displayed an intracellular trafficking defect and was trapped in the endoplasmic reticulum (ER). Our results reveal that the HER2-ECD bears an essential “activating” region that is indispensable for HER2-mediated oncogenic transformation. Targeting and eliminating this “activating” element in HER2 seems to provide a strong innovative approach for developing a valuable novel anti-HER2 therapeutic drug that would specifically benefit patients with HER2 positive tumors resistant to current therapies. Citation Format: Barbara Schroeder, Ghiara Lugo, Javier Menendez, Ingrid Espinoza, Ruth Lupu. Identification of a key region in the HER2 subdomain III required for transformation capability. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 133. doi:10.1158/1538-7445.AM2015-133

Abstract The extent of T cell infiltrates in the primary tumor is one of the most important prognostic factors in colorectal cancer (CRC). Still, a putative causal role of T cell infiltrates for prolonged patient survival remains unclear. To answer this question, we studied the presence and functional activity of tumor infiltrating lymphocytes (TIL) together with their specificity in CRC patients and correlated the obtained results to long term survival. We have utilized intracytoplasmic cytokine staining, conjointly with human leukocyte antigen (HLA)- multimers loaded with peptides derived from tumor antigen (TA), as well as antigen specific cytokine secretion assays, to demonstrate that tumor necrosis factor alpha (TNFα) expression characterizes a population of TA specific, in situ active cytotoxic T cells. TNFα was increased in CRC tumors only when patients develop spontaneous systemic T cell responses, as elucidated by IFN-γ Elispot, and this increase correlated with the number of TNFα expressing tumor infiltrating T cells. Based on these observations we concluded that intratumoral TNFα can be a direct indicator of the in situ functionality of tumor specific effector T cells in CRC. In accordance, intratumoral TNFα concentration was an independent long term prognostic factor in a retrospective multivariate analysis of a cohort of 102 CRC patients involving various other immune parameters, such as CD4+, CD8+ T cell infiltration, presence of regulatory T cells or mast cells. In conclusion, our findings provide evidence for a causal relationship between T cell infiltrates and improved survival in CRC patients as the prognostic impact of T cell infiltrates depends on small subpopulations of in situ active TA specific T cells. Furthermore TNFα, as an indicator for the functionality of TIL, might be better and more accurate prognostic parameter in CRC than mere T cell infiltration. Citation Format: Slava Stamova, Christoph Reissfelder, Christina Gossmann, Marion Braun, Andreas Bonertz, Ute Walliczek, Moritz Koch, Axel Benner, Dirk Jäger, Niels Halama, Khashayarsha Khazaie, Jürgen Weitz, Philipp Beckhove. In situ activity of tumor specific CTL is a prognostic factor in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1283. doi:10.1158/1538-7445.AM2015-1283

Abstract Dysregulation of autophagy and altered metabolic pathways are frequently observed in cancer. Due to these alterations, pharmacological targeting of these two pathways simultaneously could provide a viable therapeutic option. Although the association between these two pathways is well characterized in metabolic disorders, it is not well defined in ovarian cancer (OVCA). In this regard, we found that loss of endosulfatase HSulf-1, a known putative tumor suppressor, suppresses LC3-GFP foci formation and promotes increased lipid droplet (LD) biogenesis suggesting that absence of HSulf-1 in OVCA affects both autophagy and lipid metabolism. While isogenic cells with genetic ablation of HSulf-1 (OV202Sh1/2 and TOV2223Sh1 cells) displayed LDs, the nontargeted control transduced (NTC) OV202 and TOV2223 cells had significantly less LDs. In contrast, Transmission Electron Micrographs (TEMs) showed that OV202 and TOV2223 NTC cells had significantly more autophagic vacuoles (AVs) compared to their isogenic ShRNA targeted cells. Conversely, ectopic expression of HSulf-1 in SKOV3 cells decreased the number of LDs and increased the number of AVs compared to vector transfected controls. Here we report that OV202Sh1 cells and HSulf-1 deficient OV2008 cells have increased p-cPLA2α(ser505) levels that are associated with biogenesis of large number of LDs with reduced AVs. Interestingly, pharmacological inhibition of cPLA2α with AACOCF3 in OV202Sh1 cells resulted in reduced LD biogenesis, inhibited colony formation and reduced tumorigenesis in vivo. More importantly, treatment of HSulf-1 deficient cells with HS mimetic PG545 which can compensate for loss of HSulf-1, reduced LD biogenesis, promoted autophagy and inhibited tumor growth in vivo. Collectively, these results show a critical role of HSulf-1 in regulating both autophagy and LD biogenesis in ovarian cancer. Citation Format: Debarshi Roy, Susmita Mondal, Ashwani Khurana, Xiaoping He, Edward Hammond, Keith Dredge, Viji Shridhar. Loss of HSulf-1 promotes defective autophagy and increased lipid droplet biogenesis in ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1135. doi:10.1158/1538-7445.AM2015-1135

Background and Purpose— The ABC/2 score estimates intracerebral hemorrhage (ICH) volume, yet validations have been limited by small samples and inappropriate outcome measures. We determined accuracy of the ABC/2 score calculated at a specialized reading center (RC-ABC) or local site (site-ABC) versus the reference-standard computed tomography–based planimetry (CTP). Methods— In Minimally Invasive Surgery Plus Recombinant Tissue-Type Plasminogen Activator for Intracerebral Hemorrhage Evacuation-II (MISTIE-II), Clot Lysis Evaluation of Accelerated Resolution of Intraventricular Hemorrhage (CLEAR-IVH) and CLEAR-III trials. ICH volume was prospectively calculated by CTP, RC-ABC, and site-ABC. Agreement between CTP and ABC/2 was defined as an absolute difference up to 5 mL and relative difference within 20%. Determinants of ABC/2 accuracy were assessed by logistic regression. Results— In 4369 scans from 507 patients, CTP was more strongly correlated with RC-ABC ( r 2 =0.93) than with site-ABC ( r 2 =0.87). Although RC-ABC overestimated CTP-based volume on average (RC-ABC, 15.2 cm 3 ; CTP, 12.7 cm3), agreement was reasonable when categorized into mild, moderate, and severe ICH (κ=0.75; P <0.001). This was consistent with overestimation of ICH volume in 6 of 8 previous studies. Agreement with CTP was greater for RC-ABC (84% within 5 mL; 48% of scans within 20%) than for site-ABC (81% within 5 mL; 41% within 20%). RC-ABC had moderate accuracy for detecting ≥5 mL change in CTP volume between consecutive scans (sensitivity, 0.76; specificity, 0.86) and was more accurate with smaller ICH, thalamic hemorrhage, and homogeneous clots. Conclusions— ABC/2 scores at local or central sites are sufficiently accurate to categorize ICH volume and assess eligibility for the CLEAR-III and MISTIE III studies and moderately accurate for change in ICH volume. However, accuracy decreases with large, irregular, or lobar clots. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: MISTIE-II NCT00224770; CLEAR-III NCT00784134.

Abstract Methyl-lysine (Kme) recognition domains play a central role in epigenetic regulation during cellular differentiation, development, and gene transcription with more than 200 known “reader” domains in the human proteome. We describe our target-class approach to ligand design and discovery for three cancer relevant members of this large family: L3MBTL3 (a Malignant Brain Tumor (MBT) domain containing reader), 53BP1 (a tandem Tudor domain) and CBX7 (a chromo domain). The advantages of a small molecule driven approach to modulating chromatin biology are numerous: temporal resolution; mechanistic flexibility (targeting a specific activity of a protein as opposed to ablating them all with transgenic knock-outs or RNA-interference techniques); ease of delivery; and most significantly, when warranted, a small molecule tool has the potential to provide an immediate transition to a drug discovery effort, potentially cutting years off the time between target validation and therapeutic intervention. UNC1215 binds the MBT domains of L3MBTL3 with a Kd of 120 nM, competitively displacing mono- or dimethyl-lysine containing peptides. This probe is greater than 50-fold selective versus other members of the human MBT family and also demonstrates selectivity against more than 200 other Kme reader domains examined. UNC1215 increases the cellular mobility of GFP-L3MBTL3 fusion proteins and point mutants that disrupt the Kme binding function of GFP-L3MBTL3 phenocopy the effects of UNC1215. The potency, specificity, and cellular effects of UNC1215 establish it as the first cell-active antagonist of a Kme reader domain and a useful chemical probe for biological studies of the function of L3MBTL3 (James, L. I. et al. Nat Chem Biol 2013, 9, 184-191). 53BP1 is a Kme binding protein that plays a central biological role in DNA Damage Repair (DDR) pathway via its recruitment to sites of DNA double strand breaks (DSB). BRCA1 is a checkpoint and DNA damage repair gene that is required for maintenance of genomic integrity, and the inheritance of mutated BRCA1 is a major risk factor for breast and ovarian cancer. The BRCA1 knockout murine model is embryonic lethal and a conditional knockout in mammary glands results in low frequency and long latency of mammary tumor formation. It was recently reported that the BRCA1-null developmental phenotype is rescued when placed on a 53BP1-null background. Adult mice from this model, that are null for both the 53BP1 and BRCA1 genes, age normally and display a very low incidence of tumor formation. Genomic instability can be rescued in 53BP1 knockouts because the homologous recombination (HR) pathway is largely restored in cells lacking both BRCA1 and 53BP1 (Cao, L. et al. Molecular cell 2009, 35 (4), 534-41). Based on this data, small molecule antagonists of 53BP1's biological function could act as viable therapeutics to restore HR in the DDR response in humans with BRAC1 mutations. We will report the first small molecule, fragment-like ligands with selectivity for binding to 53BP1. CBX7 is a chromo domain containing Kme reader that, along with other CBX domains, recruits the PRC1 complex to histone 3, lysine 27 trimethylation sites (H3K27me3) and enables transcriptional silencing downstream of the PRC2 complex which ‘writes’ the H3K27me3 mark via the catalytic activity of EZH2. As EZH2 is a well validated drug target with inhibitors now entering the clinic for the treatment of various cancers, we hypothesize that antagonism of the PRC1 complex recognition of H3K27me3 will phenocopy and perhaps synergize with the activity of EZH2 inhibitors (Konze, K. D. et al. ACS Chemical Biology 2013, 8, 1324-1334). Progress towards a chemical probe to validate CBX7 as a therapeutic target will be presented. The pursuit of high quality chemical probes for KMe reader proteins represents an emerging area that will open new avenues of research in chromatin biology and may in time, translate to new therapeutic approaches. Antagonists of the readers of acetylated lysine (BRD4 bromo domains) derived from pioneering chemical probe efforts (Filippakopoulos, P. et al. Nature 468, 1067-73 (2010)) have recently entered the clinic for the treatment of various malignancies and we hope that our chemical probe work will help to validate Kme readers as novel and significant anti-tumor targets. Citation Format: Lindsey I. James, Jake I. Stuckey, Brandi M. Baughman, Michael T. Perfetti, Samantha G. Pattenden, Brad M. Dickson, Jacqueline L. Norris, Gaofeng Cui, Pavel Mader, Aiping Dong, Yunxiang Mu, Scott B. Rothbart, Brian D. Strahl, Jinrong Min, Peter J. Brown, Dmitri B. Kireev, William P. Janzen, Kevin M. McBride, Mark T. Bedford, Georges Mer, Cheryl H. Arrowsmith, Stephen V. Frye. Targeting chromatin regulation for cancer therapy: progress towards chemical probes for methyl-lysine readers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr SY08-03. doi:10.1158/1538-7445.AM2015-SY08-03

Abstract Stool DNA testing has evolved into a highly accurate and well-validated test for the screen-detection of colorectal neoplasia. An optimized multi-target stool DNA test (MT-sDNA) achieves the same high point-sensitivities as reported with colonoscopy for early-stage colorectal cancer (CRC) and significantly higher sensitivity than by fecal immunochemical blood testing (FIT) for detection of both cancer and advanced precancer. Thus, MT-sDNA sets a new high criterion standard for the noninvasive screen-detection of colorectal neoplasia. With clinical application, MT-sDNA has potential to meaningfully address current gaps in our approach to CRC screening through benefits of its high accuracy on screening effectiveness, user-friendly features on patient compliance, and easy mail-out distribution on test access. After an unprecedented parallel review, the U.S. Food & Drug Administration (FDA) and Center for Medicaid and Medicare Services (CMS) simultaneously endorsed MT-sDNA for general CRC screening in August 2014, and the test is now available for clinical use. This overview briefly summarizes the clinical validation, addresses central clinical questions at implementation, and touches on future applications of stool DNA testing. Despite efforts to date, CRC remains the 2nd leading cause of cancer mortality in the US and screening rates are suboptimal. Conventional screening tools are variably hampered by invasiveness, unpleasant bowel preparation, access limitations, interruption of work routines, and a bias toward left-sided lesion detection which compromise efficacy and participation. There is an imperative to improve screening effectiveness through more accurate, patient-friendly, and accessible approaches. Multi-Target Stool DNA Test (MT-sDNA) Stool DNA testing is grounded in the rational biology of exfoliation, inherent discrimination afforded by tumor-associated genetic and epigenetic alterations, and exquisite analytical sensitivity of new assay methods (Pathology 2012;44:8-0). Key technical innovations leading to the current high test performance include use of a stool buffer to prevent DNA degradation, discriminant new marker panels, and advanced analytical platforms that substantially augment sensitivity. MT-sDNA, an optimized and automated new generation test and the product of an intensive research and development effort, has been described in detail (Clin Gastroenterol Hepatol 2013; 11:1313). It targets two highly discriminant methylated genes (BMP3 and NDRG4), the informative KRAS mutations, a marker for total human DNA (β-actin), and fecal hemoglobin. Quantitative outputs analyzed in a software system yield a positive or negative result based on an established cutoff score. With tightly reproducible results via automation, MT-sDNA avoids the operator variation that hinders quality with endoscopic and subjective in vitro screening methods. This noninvasive test requires no bowel preparation, diet or medication restrictions, or missed work time. Stools can be collected at home and mailed to a central laboratory for processing. Clinical Validation Case-Control Studies. In the first large multicenter study using next generation technology (Gastroenterology 2012;142:248), a prototype MT-sDNA showed high neoplasm detection unaffected by tumor stage or site. In the second study (Clin Gastroenterol Hepatol 2013;11:1313), an optimized MT-sDNA detected 98% of CRC at specificity of 91% and again was unaffected by stage or site. Adenoma detection increased with size and degree of dysplasia: sensitivity for adenomas &gt;1cm was 57%, &gt;2 cm was 73%, and &gt;3 cm was 83%; sensitivity was 83% with high-grade dysplasia (HGD), 94% of which occurred in lesions &gt;2 cm. In a third study (PloS One 2014;9:e85659), MT-sDNA detected 55% of sessile serrated polyps (SSP) &gt;1cm compared to 10% by fecal immune-testing for blood (FIT) at matched specificities. Pivotal Screen-Setting Study. In a multicenter cross-sectional study comprising &gt;10,000 average risk persons from across North America (NEJM 2014;370:1287), MT-sDNA detected 92% of CRC (94% of stage I-II), 69% of HGD, 66% of adenomas &gt;2cm, and 42% of advanced adenomas (&gt;1cm or with villous features) + SSP &gt;1cm. Specificity was 90% based on normal colonoscopy. MT-sDNA superiority over FIT was statistically significant for all lesion categories. Program Performance MT-sDNA could compare favorably with conventional methods in a longitudinal screening program. MT-sDNA achieves high point sensitivity for CRC, similar to that of colonoscopy. However, because it is practical to perform more frequently, MT-sDNA (followed by colonoscopy if positive) could improve program sensitivity by catching aggressive metachronous lesions missed by colonoscopy alone done at typical 10 year intervals. Point sensitivities of MT-sDNA for precancers could translate into very high programmatic sensitivity with repeated screening rounds, as we have estimated (Pathology 2012;44:80), and, therefore, into effective CRC prevention. Finally, MT-sDNA's point specificity of 90%, while lower than the average 95% reported for FIT, bodes well within a screening program as cumulative false-positives are most relevant. For example, MT-sDNA applied every 3 years (frequency supported by early modeling and approved by CMS) would yield roughly 3-4% false-positives/year, fewer than the 5% rate by FIT applied annually. Implementation With the clinical entry of MT-sDNA come both opportunities to improve screening outcomes and a collective responsibility to apply rational principles and evidence-based decision-making to guide and refine its use. Clinical Questions. Multiple questions will be briefly addressed in the oral presentation, including: Can FIT achieve same sensitivity by lowering its specificity?, How does MT-sDNA compare to plasma-based DNA tests?, Is MT-sDNA cost-effective?, What does the clinical use algorithm look like?, and Who would benefit from its use? With respect to the last question, while the FDA approved MT-sDNA for average-risk screening, other indications may evolve. A sound case can be made for interval testing between screening colonoscopies. As currently practiced, screening colonoscopy has a much lower benefit on incidence and mortality reduction from right-sided than left-sided CRC, interval cancers are disproportionately right-sided, and quality metrics of this operator-dependent procedure vary widely. Because of its very high sensitivity for CRC that is unaffected by tumor site and its superior sensitivity over FIT for detection of sessile serrated polyps and those adenomas at greatest risk of progression, MT-sDNA seems well-suited for consideration as an interval test. In instances of inadequately prepared or incomplete colonoscopy, which occur in 15 - 25% of colonoscopies, MT-sDNA testing may offer a convenient follow-up alternative to repeat colonoscopy or other imaging methods, particularly among those reticent or unwilling to undergo repeat bowel preparation and invasive testing. In low CRC risk surveillance populations, such as patients with a single small adenoma, use of MT-sDNA might be explored as a resource-savings approach. Those at high CRC risk represent another potential target group for surveillance. A premise for the recommendation of colonoscopy as the choice for high risk surveillance has been its unparalleled high sensitivity. However, in light of the recent MT-sDNA validation studies showing similarly high point-sensitivity for early-stage CRC and estimates suggesting comparable program-sensitivity for advanced precancers, it is intriguing to re-consider noninvasive surveillance in this setting. Further studies are clearly needed. Meanwhile, in high risk individuals refusing or unable to access colonoscopy and in those with relative contraindications to colonoscopy, surveillance by MT-sDNA might be considered. The Future: Expanded Applications Inflammatory Bowel Disease (IBD). IBD patients are at increased CRC risk, and stool DNA testing may help to improve surveillance detection and compliance rates. In a feasibility study (Aliment Pharmacol Ther 2013;37:546), highly accurate detection of both CRC and HGD in IBD patients was observed by stool assay of methylated DNA markers alone. Supra-colonic Cancers: There remains an enormous unmet need for early detection of cancers above the colon, which collectively exact a death toll 2-times higher than that of CRC in the US and 4-times higher globally. Based on our early observations, stool DNA testing represents a potential strategy to fill this void. If combined with CRC screening, it would be ideal to differentiate upper from lower GI lesions; and preliminary data suggest that site-specific DNA tumor markers can be identified (Gastroenterology 2013;144:S-84). Clearly, more studies are needed and warranted. As stool DNA testing moves from historical promise into primetime, efficient implementation systems and essential linkages with endoscopy will need to be established to achieve highest impact. Logical extensions of this powerful molecular technology open intriguing opportunities to expand its value. Citation Format: David A. Ahlquist. Stool DNA detection of colorectal neoplasia: A new high bar for noninvasive screening. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr PL02-01. doi:10.1158/1538-7445.AM2015-PL02-01