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Ryan, David

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Ryan, David
Author's Publications: search.filters.isAuthorOfPublication.13fc4684-a2d2-454b-83b6-1159ed5f323d

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Now showing 1 - 7 of 7
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    Tumor engraftment in patient-derived xenografts of pancreatic ductal adenocarcinoma is associated with adverse clinicopathological features and poor survival
    (Public Library of Science, 2017) Pergolini, Ilaria; Morales-Oyarvide, Vicente; Mino-Kenudson, Mari; Honselmann, Kim C.; Rosenbaum, Matthew; Nahar, Sabikun; Kem, Marina; Ferrone, Cristina; Lillemoe, Keith; Bardeesy, Nabeel; Ryan, David; Thayer, Sarah P.; Warshaw, Andrew; Fernandez-Del Castillo, Carlos; Liss, Andrew
    Patient-derived xenograft (PDX) tumors are powerful tools to study cancer biology. However, the ability of PDX tumors to model the biological and histological diversity of pancreatic ductal adenocarcinoma (PDAC) is not well known. In this study, we subcutaneously implanted 133 primary and metastatic PDAC tumors into immunodeficient mice. Fifty-seven tumors were successfully engrafted and even after extensive passaging, the histology of poorly-, moderately-, and well-differentiated tumors was maintained in the PDX models. Moreover, the fibroblast and collagen contents in the stroma of patient tumors were recapitulated in the corresponding PDX models. Analysis of the clinicopathological features of patients revealed xenograft tumor engraftment was associated with lymphovascular invasion (P = 0.001) and worse recurrence-free (median, 7 vs. 16 months, log-rank P = 0.047) and overall survival (median, 13 vs. 21 months, log-rank P = 0.038). Among successful engraftments, median time of growth required for reimplantation into new mice was 151 days. Reflective of the inherent biological diversity between PDX tumors with rapid (<151 days) and slow growth, differences in their growth were maintained during extensive passaging. Rapid growth was additionally associated with lymph node metastasis (P = 0.022). The association of lymphovascular invasion and lymph node metastasis with PDX formation and rapid growth may reflect an underlying biological mechanism that allows these tumors to adapt and grow in a new environment. While the ability of PDX tumors to mimic the cellular and non-cellular features of the parental tumor stroma provides a valuable model to study the interaction of PDAC cells with the tumor microenvironment, the association of successful engraftment with adverse clinicopathological features suggests PDX models over represent more aggressive forms of this disease.
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    Pancreatic Ductal Adenocarcinoma
    (Ovid Technologies (Wolters Kluwer Health), 2013) Konstantinidis, Ioannis T; Warshaw, Andrew; Allen, Jill; Blaszkowsky, Lawrence; Castillo, Carlos; Deshpande, Vikram; Hong, Theodore; Kwak, Eunice Lee; Lauwers, Gregory Y.; Ryan, David; Wargo, Jennifer Ann; Lillemoe, Keith; Ferrone, Cristina
    Objective: Patients who undergo an R0 resection of their pancreatic ductal adenocarcinoma (PDAC) have an improved survival compared with patients who undergo an R1 resection. It is unclear whether an R1 resection confers a survival benefit over locally advanced (LA) unresectable tumors. Our aim was to compare the survival of patients undergoing an R1 resection with those having LA tumors and to explore the prognostic significance of a 1-mm surgical margin. Methods: Clinicopathologic data from a pancreatic cancer database between January 1993 and July 2008 were reviewed. Locally advanced tumors had no evidence of metastatic disease at exploration. Results: A total of 1705 patients were evaluated for PDAC in the Department of Surgery. Of the 1084 (64%) patients who were surgically explored, 530 (49%) were considered unresectable (286 locally unresectable, 244 with distant metastasis). One hundred fifty-seven (28%) of the resected PDACs had an R1 resection. Patients undergoing an R1 resection had a slightly longer survival compared with those who had locally advanced unresectable cancers (14 vs 11 months; P < 0.001). Patients with R0 resections had a favorable survival compared with those with R1 resections (23 vs 14 months; P < 0.001), but survival after resections with 1-mm margin or less (R0-close) were similar to R1 resections: both groups had a significantly shorter median survival than patients with a margin of greater than 1 mm (R0-wide) (16 vs 14 vs 35 months, respectively; P < 0.001). Conclusions: Patients undergoing an R1 resection still have an improved survival compared with patients with locally advanced unresectable pancreatic adenocarcinoma. R0 resections have an improved survival compared with R1 resections, but this survival benefit is lost when the tumor is within 1 mm of the resection margin.
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    A prospective feasibility study of respiratory-gated proton beam therapy for liver tumors
    (Elsevier BV, 2014) Hong, Theodore; Delaney, Thomas; Mamon, Harvey; Willett, Christopher G.; Yeap, Beow; Niemierko, Andrzej; Wolfgang, John; Lu, Hsiao-Ming; Adams, Judith; Weyman, Elizabeth A.; Arellano, Ronald; Blaszkowsky, Lawrence; Allen, Jill; Tanabe, Kenneth; Ryan, David; Zhu, Andrew
    Purpose To evaluate the feasibility of a respiratory-gated proton beam therapy for liver tumors. Materials and Methods Fifteen patients were enrolled on a prospective IRB-approved protocol. Eligibility criteria included Childs-Pugh A/B cirrhosis, unresectablebiopsy-proven hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), or metastatic disease (solid tumors only), 1-3 lesions, and tumor size of ≤6 cm. Patients received 15 fractions to a total dose of 45-75 GyE using respiratory-gated proton beam therapy. Gating was performed with an external respiratory position monitoring (RPM) based system. Results Of the15 patients enrolled on this clinical trial, 11 had HCC, 3 had ICC, and 1had metastasis from another primary. Ten patients had a single lesion, 3 patients had 2 lesions, and 2 patients 3 lesions. Toxicities were: Gr 3 bilirubinemia- 2, Gr 3 gastrointestinal bleed- 1, and Gr 5 stomach perforation-1. One patient had a marginal recurrence, 3 had hepatic recurrences elsewhere in the liver, and 2 had extrahepatic recurrence. With a median follow-up for survivors of 69 months, 1-yr, 2-yr, 3-yr OS is 53%, 40%, and 33% respectively. PFS is 40%,33% and 27% at 1, 2, and 3 years, respectively. Conclusion Respiratory-gated proton beam therapy for liver tumors is feasible. Phase II studies for primary liver tumors and metastatic tumorsare underway.
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    RNA Sequencing of Pancreatic Circulating Tumour Cells Implicates WNT Signaling in Metastasis
    (2012) Yu, Min; Ting, David; Stott, Shannon; Wittner, Ben; Ozsolak, Fatih; Paul, S.; Ciciliano, Jordan C.; Smas, Malgorzata E.; Winokur, Daniel; Gilman, Anna J.; Ulman, Matthew J.; Xega, Kristina; Contino, Gianmarco; Alagesan, Brinda; Brannigan, Brian W.; Milos, Patrice M.; Ryan, David; Sequist, Lecia; Bardeesy, Nabeel; Ramaswamy, Sridhar; Toner, Mehmet; Maheswaran, Shyamala; Haber, Daniel
    Circulating tumour cells (CTCs) shed into blood from primary cancers include putative precursors that initiate distal metastases. While these cells are extraordinarily rare, they may identify cellular pathways contributing to the blood-borne dissemination of cancer. Here, we adapted a microfluidic device for efficient capture of CTCs from an endogenous mouse pancreatic cancer model and subjected CTCs to single molecule RNA sequencing, identifying Wnt2 as a candidate gene enriched in CTCs. Expression of Wnt2 in pancreatic cancer cells suppresses anoikis, enhances anchorage-independent sphere formation, and increases metastatic propensity in vivo. This effect is correlated with fibronectin upregulation and suppressed by inhibition of Map3k7 (Tak1) kinase. In humans, formation of non-adherent tumour spheres by pancreatic cancer cells is associated with upregulation of multiple Wnt genes, and pancreatic CTCs revealed enrichment for Wnt signaling in 5 of 11 cases. Thus, molecular analysis of CTCs may identify candidate therapeutic targets to prevent the distal spread of cancer.
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    A Multicenter Retrospective Study on Clinical Characteristics, Treatment Patterns, and Outcome in Elderly Patients with Hepatocellular Carcinoma
    (AlphaMed Press, 2011) Kozyreva, Olga N.; Chi, Dorcas; Clark, Jeffrey; Wang, Hejing; Theall, Kathy P.; Ryan, David; Zhu, Andrew
    Background. There is a paucity of information on the clinical presentation and outcome of elderly hepatocellular carcinoma (HCC) patients. We performed a multicenter retrospective comparative study to assess the impact of age on potential differences in clinical characteristics, treatment patterns, and outcome in HCC patients. Methods. We retrospectively analyzed HCC patients treated at two U.S. tertiary institutions from 1998 to 2008. Demographics, tumor parameters, etiology and severity of cirrhosis, treatment, and survival from diagnosis were collected and analyzed. After exclusion of transplanted patients, survival analyses were performed using the Kaplan-Meier method with log-rank tests and Cox proportional hazards models. Results. Three hundred thirty-five HCC patients were divided into two groups: “elderly” (95 patients, age ≥70 years) and “younger” (240 patients, aged <70 years). The male/female (M/F) ratio was 5.8:1 and 1.7:1 in the younger and elderly groups, respectively (p < .0001). Hepatitis C virus (HCV) infection rate was 48.3% in younger and 21.1% in elderly patients (p < .0001); Child class B and C cirrhosis accounted for 35.8% in younger and 25.3% in elderly patients (p = .063). Compared with younger patients, the elderly received transplant less frequently (19.6% versus 5.3%, p = .0002) and were more likely to receive supportive care only (22.9% versus 36.8%, p = .01). No significant differences between the two age groups were seen in tumor parameters or other treatments received. Overall (p = .47) and HCC-specific survival rates (p = .38) were similar in both age groups. Conclusions. Characteristics that distinguish elderly from younger HCC patients include lower M/F ratio, worse performance status, lower rate of HCV infection, and less advanced underlying cirrhosis. Elderly patients were less likely to have a liver transplant and more likely to receive supportive care only. However, overall and HCC-specific survival were similar between the two groups.
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    Toxic Metals in Aquatic Ecosystems: A Microbiological Perspective
    (The National Institute of Environmental Health Sciences, 1995) Ford, Timothy; Ryan, David
    Microbe-metal interactions in aquatic environments and their exact role in transport and transformations of toxic metals are poorly understood. This paper will briefly review our understanding of these interactions. Ongoing research in Lake Chapala, Mexico, the major water source for the City of Guadalajara, provides an opportunity to study the microbiological aspects of metal-cycling in the water column. Constant resuspension of sediments provides a microbiologically rich aggregate-based system. Data indicate that toxic metals are concentrated on aggregate material and bioaccumulate in the food chain. A provisional model is presented for involvement of microbial aggregates in metal-cycling in Lake Chapala.
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    Long Term Survivors with Metastatic Pancreatic Adenocarcinoma Treated with Gemcitabine: A Retrospective Analysis
    (BioMed Central, 2009) Goulart, Bernardo HL; Clark, Jeffrey; Lauwers, Gregory Y.; Ryan, David; Grenon, Nina; Muzikansky, Alona; Zhu, Andrew
    Background: Metastatic pancreatic adenocarcinoma has a short median overall survival (OS) of 5–6 months. However, a subgroup of patients survives more than 1 year. We analyzed the survival outcomes of this subgroup and evaluated clinical and pathological factors that might affect survival durations. Methods: We identified 20 patients with metastatic or recurrent pancreatic adenocarcinoma who received single-agent gemcitabine and had an OS longer than 1 year. Baseline data available after the diagnosis of metastatic or recurrent disease was categorized as: 1) clinical/demographic data (age, gender, ECOG PS, number and location of metastatic sites); 2) Laboratory data (Hematocrit, hemoglobin, glucose, LDH, renal and liver function and CA19-9); 3) Pathologic data (margins, nodal status and grade); 4) Outcomes data (OS, Time to Treatment Failure (TTF), and 2 year-OS). The lowest CA19-9 levels during treatment with gemcitabine were also recorded. We performed a univariate analysis with OS as the outcome variable. Results: Baseline logarithm of CA19-9 and total bilirubin had a significant impact on OS (HR = 1.32 and 1.31, respectively). Median OS and TTF on gemcitabine were 26.9 (95% CI = 18 to 32) and 11.5 (95% CI = 9.0 to 14.3) months, respectively. Two-year OS was 56.4%, with 7 patients alive at the time of analysis. Conclusion: A subgroup of patients with metastatic pancreatic cancer has prolonged survival after treatment with gemcitabine. Only bilirubin and CA 19-9 levels were predictive of longer survival in this population. Further analysis of potential prognostic and predictive markers of response to treatment and survival are needed.