The role of clinical care pathways: an experience with distal pancreatectomy

BACKGROUND

Previous studies have indicated that clinical pathways may shorten hospital length of stay (HLOS) among patients undergoing distal pancreatectomy (DP). Here, we evaluate an institutional standardized care pathway (SCP) for patients undergoing DP.

MATERIALS AND METHODS

A retrospective review of patients undergoing DP from November 2006 to November 2012 was completed. Patients treated before and after implementation of the SCP were compared. Multivariable linear regression was then performed to identify independent predictors of HLOS.

RESULTS

There were no differences in patient characteristics between SCP (n=50) and pre-SCP patients (n=100). Laparoscopic technique (62% versus 13%, P<0.001), splenectomy (52% versus 38%, P=0.117), and concomitant major organ resection (24% versus 13%, P=0.106) were more common among SCP patients. Overall, important complication rates were similar (24% versus 26%, P=0.842). SCP patients resumed a normal diet earlier (4 versus 5 d, P=0.025) and had shorter HLOS (6 versus 7 d, P=0.026). There was no increase in 30-d resurgery or readmission. In univariate comparison, SCP, cancer diagnoses, intraductal papillary mucinous neoplasm diagnoses, neoadjuvant therapy, operative technique, major organ resection, and feeding tube placement were associated with HLOS; however, after multivariable adjustment, only laparoscopic technique (-33%, P=0.001), concomitant major organ resection (+38%, P<0.001), and feeding tube placement (+68%, P<0.001) were independent predictors of HLOS.

CONCLUSIONS

Implementation of a clinical pathway did not improve HLOS at our institution. The increasing use of laparoscopy likely accounts for shorter HLOS in the SCP cohort. In the future, it will be important to identify clinical scenarios most likely to benefit from implementation of a clinical pathway.

Hepatic resection for hepatocellular carcinoma: do contemporary morbidity and mortality rates demand a transition to ablation as first-line treatment?

BACKGROUND

Despite the rising incidence of hepatocellular carcinoma (HCC), challenges and controversy persist in optimizing treatment. As recent randomized trials suggest that ablation can have oncologic equivalence compared with resection for early HCC, the relative morbidity of the 2 approaches is a central issue in treatment decisions. Although excellent contemporary perioperative outcomes have been reported by a few hepatobiliary units, it is not clear that they can be replicated in broader practice. Our objective was to help inform this treatment dilemma by defining perioperative outcomes in a broader set of patients as represented in NSQIP-participating institutions.

STUDY DESIGN

Mortality and morbidity data were extracted from the 2005-2010 NSQIP Participant Use Data Files based on Current Procedural Terminology (hepatectomy and ablation) and ICD-9 (HCC). Perioperative outcomes were reviewed, and factors associated with morbidity and mortality were identified with multivariable logistic regression.

RESULTS

Eight hundred and thirty-seven (52%) underwent minor hepatectomy, 444 (28%) underwent major hepatectomy, and 323 (20%) underwent surgical ablation. Mortality rates were 3.4% for minor hepatectomy, 3.7% for ablation, and 8.3% for major hepatectomy (p < 0.01). Major complication rates were 21.3% for minor hepatectomy, 9.3% for ablation, and 35.1% for major hepatectomy (p < 0.01). When controlling for confounders, ablation was associated with decreased mortality (adjusted odds ratio = 0.20; 95% CI, 0.04-0.97; p = 0.046) and major complications (adjusted odds ratio = 0.34; 95% CI, 0.22-0.52; p < 0.001).

CONCLUSIONS

Exceedingly high complication rates after major hepatectomy for HCC exist in the broader NSQIP treatment environment. These data strongly support the use of parenchymal-sparing minor resections or ablation over major hepatectomy for early HCC when feasible.

Further characterization of the target of a potential aptamer biomarker for pancreatic cancer: cyclophilin B and its posttranslational modifications

Posttranslational modifications on proteins can serve as useful biomarkers for disease. However, their discovery and detection in biological fluids is challenging. Aptamers are oligonucleotide ligands that demonstrate high affinity toward their target proteins and can discriminate closely related proteins with superb specificity. Previously, we generated a cyclophilin B aptamer (M9-5) that could discriminate sera from pancreatic cancer patients and healthy volunteers with high specificity and sensitivity. In our present work we further characterize the aptamer and the target protein, cyclophilin B, and demonstrate that the aptamer could discriminate between cyclophilin B expressed in human cells versus bacteria. Using mass-spectrometric analysis, we discovered post-translational modifications on cyclophilin B that might be responsible for the M9-5 selectivity. The ability to distinguish between forms of the same protein with differing post-translational modifications is an important advantage of aptamers as tools for identification and detection of biomarkers.

Concomitant vascular reconstruction during pancreatectomy for malignant disease: a propensity score-adjusted, population-based trend analysis involving 10,206 patients

OBJECTIVE

To assess trends in the frequency of concomitant vascular reconstructions (VRs) from 2000 through 2009 among patients who underwent pancreatectomy, as well as to compare the short-term outcomes between patients who underwent pancreatic resection with and without VR.

DESIGN

Single-center series have been conducted to evaluate the short-term and long-term outcomes of VR during pancreatic resection. However, its effectiveness from a population-based perspective is still unknown. Unadjusted, multivariable, and propensity score-adjusted generalized linear models were performed.

SETTING

Nationwide Inpatient Sample from 2000 through 2009.

PATIENTS

A total of 10,206 patients were involved.

MAIN OUTCOME MEASURES

Incidence of VR during pancreatic resection, perioperative in-hospital complications, and length of hospital stay.

RESULTS

Overall, 10,206 patients were included in this analysis. Of these, 412 patients (4.0%) underwent VR, with the rate increasing from 0.7% in 2000 to 6.0% in 2009 (P < .001). Patients who underwent pancreatic resection with VR were at a higher risk for intraoperative (propensity score-adjusted odds ratio, 1.94; P = .001) and postoperative (propensity score-adjusted odds ratio, 1.36; P = .008) complications, while the mortality and median length of hospital stay were similar to those of patients without VR. Among the 25% of hospitals with the highest surgical volume, patients who underwent pancreatic surgery with VR had significantly higher rates of postoperative complications and mortality than patients without VR.

CONCLUSIONS

The frequency of VR during pancreatic surgery is increasing in the United States. In contrast with most single-center analyses, this population-based study demonstrated that patients who underwent VR during pancreatic surgery had higher rates of adverse postoperative outcomes than their counterparts who underwent pancreatic resection only. Prospective studies incorporating long-term outcomes are warranted to further define which patients benefit from VR.

Examining reoperation and readmission after hepatic surgery

BACKGROUND

Although the perioperative mortality from hepatic resection has improved considerably, this procedure is still associated with substantial morbidity and resource use. The goal of this investigation was to characterize the incidence, patterns, and risk factors for early reoperation and readmission after hepatectomy.

STUDY DESIGN

Perioperative outcomes of 1,281 patients undergoing hepatic resection at an academic center from 1996 to 2009 were analyzed. The indications for early reoperation and readmission (90 days) were reviewed. Multivariate logistic regression analysis was performed to determine variables associated with reoperation and readmission. A scoring system was generated to predict the need for readmission after hepatectomy.

RESULTS

Eighty-seven patients (6.8%) required reoperation. The perioperative mortality in patients requiring reoperation was significantly higher than for those not requiring reoperation (23.0% vs 3.4%; p < 0.001). Variables associated with reoperation included male sex, performance of concomitant major nonhepatic procedures, and greater intraoperative blood loss. One hundred and eighty-four patients (14.4%) required readmission. Variables associated with readmission included major hepatectomy, development of major postoperative complications, and index hospitalization >7 days. A Readmission Prediction Score ranging from 0 to 4 was generated and directly correlated with need for readmission.

CONCLUSIONS

In the current era of hepatic surgery, early reoperation and readmission remain relatively frequent. As we care for patients who are increasingly receiving regionalized care far from home, we must be mindful of patients at increased risk for readmission. The development of strategies to minimize the complications that necessitate reoperation and readmission is critical to improving patient care.

The role of local excision in invasive adenocarcinoma of the ampulla of Vater

BACKGROUND

Ampulla of Vater carcinomas are rare malignancies that have been traditionally treated with radical surgical resection. Given the mortality associated with pancreaticoduodenectomy, some patients may benefit from local resection. A single-institution outcomes analysis was performed to define the role of local resection.

METHODS

Patients undergoing local resection (ampullectomy) for ampullary carcinomas at Duke University between 1976 and 2010 were analyzed retrospectively. Time-to-event analysis was conducted analyzing all patients undergoing surgery, with and without adjuvant chemoradiation therapy (CRT). Overall survival (OS), local control (LC), metastases-free survival (MFS), and disease-free survival (DFS) were studied using Kaplan-Meier analysis.

RESULTS

A total of 17 patients with invasive carcinoma underwent ampullectomy. The 3-and 5-year LC, MFS, DFS and OS rates were 36% and 24%, 68% and 54%, 31% and 21%, and 35% and 21%, respectively. Patients receiving adjuvant CRT did not appear to have improved outcomes compared with surgery alone, although this group tended to have poorer histological grade, more advanced tumor staging and involved surgical margins.

CONCLUSIONS

Ampullectomy for invasive ampullary adenocarcinomas is a safe procedure but does not offer satisfactory long-term results, mostly due to high local failure rates. Adjuvant CRT therapy does not appear to offer increased local control or survival benefit following ampullectomy, although these results may suffer from selection bias and small sample size. Local resection should be limited to benign ampullary lesions or patients with very small, early tumors with favorable histologic features where radical resection is not feasible.

The impact of vascular resection on early postoperative outcomes after pancreaticoduodenectomy: an analysis of the American College of Surgeons National Surgical Quality Improvement Program database

BACKGROUND

Several single-center reports suggest that vascular resection (VR) during pancreaticoduodenectomy (PD) for patients with pancreatic adenocarcinoma is feasible without affecting early postoperative mortality or morbidity. Our objective is to review the outcomes associated with VR during PD using a large multicenter data source.

METHODS

A retrospective cohort analysis was performed using the National Surgical Quality Improvement Program Participant User Files for 2005-2009. All patients undergoing PD for a postoperative diagnosis of malignant neoplasm of the pancreas were included. Forward stepwise multivariate regression analysis was used to determine the association between VR during PD and 30-day postoperative mortality and morbidity after adjustment for patient demographics and comorbidities.

RESULTS

3,582 patients were included for analysis, 281 (7.8 %) of whom underwent VR during PD. VR during PD was associated with significantly greater risk-adjusted 30-day postoperative mortality [5.7 % with VR versus 2.9 % without VR, adjusted odds ratio (AOR) 2.1, 95 % confidence interval (CI) 1.22-3.73, P = 0.008] and overall morbidity (39.9 % with VR versus 33.3 % without VR, AOR 1.36, 95 % CI 1.05-1.75, P = 0.02). There was no significant difference in risk-adjusted postoperative mortality or morbidity between those patients undergoing VR by the primary surgical team versus those patients undergoing VR by a vascular surgical team.

CONCLUSIONS

Contrary to the findings of several previously published single-center analyses, the current study demonstrates increased 30-day postoperative morbidity and mortality in PD with VR when compared with PD alone.

Aptamer-mediated delivery of chemotherapy to pancreatic cancer cells

Gemcitabine is a nucleoside analog that is currently the best available single-agent chemotherapeutic drug for pancreatic cancer. However, efficacy is limited by our inability to deliver sufficient active metabolite into cancer cells without toxic effects on normal tissues. Targeted delivery of gemcitabine into cancer cells could maximize effectiveness and concurrently minimize toxic side effects by reducing uptake into normal cells. Most pancreatic cancers overexpress epidermal growth factor receptor (EGFR), a trans-membrane receptor tyrosine kinase. We utilized a nuclease resistant RNA aptamer that binds and is internalized by EGFR on pancreatic cancer cells to deliver gemcitabine-containing polymers into EGFR-expressing cells and inhibit cell proliferation in vitro. This approach to cell type-specific therapy can be adapted to other targets and to other types of therapeutic cargo.

Targeting eNOS in pancreatic cancer

Mortality from pancreatic ductal adenocarcinoma cancer (PDAC) is among the highest of any cancer and frontline therapy has changed little in years. Activation of endothelial nitric oxide synthase (eNOS, NOS3, or NOS III) has been implicated recently in the pathogenesis of PDACs. In this study, we used genetically engineered mouse and human xenograft models to evaluate the consequences of targeting eNOS in PDACs. Genetic deficiency in eNOS limited the development of preinvasive pancreatic lesions and trended toward an extended lifespan in mice with advanced pancreatic cancer. These effects were also observed upon oral administration of the clinically evaluated NOS small molecule inhibitor N(G)-nitro-L-arginine methyl ester (l-NAME). Similarly, other transgenic models of oncogenic KRas-driven tumors responded to l-NAME treatment. Finally, these results were recapitulated in xenograft models of human pancreatic cancer, in which l-NAME was found to broadly inhibit tumorigenic growth. Taken together, our findings offer preclinical proof-of-principle to repurpose l-NAME for clinical investigations in treatment of PDACs and possibly other KRas-driven human cancers.

Comparing human pancreatic cell secretomes by in vitro aptamer selection identifies cyclophilin B as a candidate pancreatic cancer biomarker

Most cases of pancreatic cancer are not diagnosed until they are no longer curable with surgery. Therefore, it is critical to develop a sensitive, preferably noninvasive, method for detecting the disease at an earlier stage. In order to identify biomarkers for pancreatic cancer, we devised an in vitro positive/negative selection strategy to identify RNA ligands (aptamers) that could detect structural differences between the secretomes of pancreatic cancer and non-cancerous cells. Using this molecular recognition approach, we identified an aptamer (M9-5) that differentially bound conditioned media from cancerous and non-cancerous human pancreatic cell lines. This aptamer further discriminated between the sera of pancreatic cancer patients and healthy volunteers with high sensitivity and specificity. We utilized biochemical purification methods and mass-spectrometric analysis to identify the M9-5 target as cyclophilin B (CypB). This molecular recognition-based strategy simultaneously identified CypB as a serum biomarker and generated a new reagent to recognize it in body fluids. Moreover, this approach should be generalizable to other diseases and complementary to traditional approaches that focus on differences in expression level between samples. Finally, we suggest that the aptamer we identified has the potential to serve as a tool for the early detection of pancreatic cancer.

Does preoperative therapy optimize outcomes in patients with resectable pancreatic cancer?

The objective of this study was to compare survival between all patients with radiographically resectable adenocarcinoma of the proximal pancreas who underwent preoperative chemoradiation therapy (PRE-OP CRT) or surgical exploration first (SURGERY) with "intention to resect." Pancreatic cancer patients who undergo resection after PREOP CRT live longer than patients who undergo resection without PREOP CRT, a difference that may be attributable to patient selection. We retrospectively identified 236 patients with pancreatic head adenocarcinoma seen between 1999 and 2007 with sufficient data to be confirmed medically and radiographically resectable. The outcomes of 144 patients who underwent PREOP CRT were compared to those of 92 patients who proceeded straight to SURGERY. The groups were similar in age and gender. Tumors were slightly larger in the PREOP CRT group (mean 2.5 cm vs. 2.1 cm, P < 0.01), and there were trends toward more venous abutment (54% vs. 39%, P = 0.06) and a higher Charlson comorbidity index (P = 0.1). In the PREOP CRT group, 76 patients (53%) underwent resection, 28 (19%) had metastatic and 17 (12%) locally unresectable disease after PREOP CRT, and 23 (16%) were not explored due to performance status or loss to follow-up. In the SURGERY group, 68 patients (74%) underwent resection. Sixteen patients (17%) had metastatic and eight patients (9%) locally unresectable disease at exploration. In patients who underwent resection, the PREOP CRT group had smaller pathologic tumor size and lower incidence of positive lymph nodes than the SURGERY group but no difference in positive margins or need for vascular resection. Median overall survival (OS) in patients undergoing resection was 27 months in the PREOP CRT group and 17 months in the SURGERY group (P = 0.04). Median OS in all patients treated with PREOP CRT or surgically explored with intention to resect was 15 and 13 months, respectively, with superimposable survival curves. Despite a lower resection rate, the PREOP CRT group as a whole had a similar OS to the SURGERY group as a whole. For patients who underwent resection, those in the PREOP CRT had longer survival than those in the SURGERY group, suggesting that PREOP CRT allows better patient selection for resection. PREOP CRT should be considered an acceptable alternative for most patients with resectable pancreatic cancer.

Vascular surgery collaboration during pancreaticoduodenectomy with vascular reconstruction

BACKGROUND

Once thought to have unresectable disease, pancreatic cancer patients with portal venous involvement are now reported to have comparable survival after pancreaticoduodenectomy (PD) with vascular reconstruction (VR) as compared with patients without vascular involvement. We hypothesize that a multidisciplinary approach involving a vascular surgeon will minimize morbidity and improve patency of VRs.

METHODS

We identified 204 patients who underwent PD for pancreatic adenocarcinoma from 1997 to 2008. Patients who underwent PD with VR (N = 42) were compared with those who underwent standard PD (N = 162). VRs were performed by a vascular surgeon and involved primary repair (N = 8), vein patch (N = 25), or interposition grafting (N = 9) with femoral or other venous conduit.

RESULTS

Patients undergoing PD with VR had larger tumors (3.0 cm vs. 2.5 cm, P < 0.01) but did not have different rates of tumor-free margins (73% vs. 72%, P = 0.84) or lymph nodes metastases (50% vs. 38%, P = 0.14). The VR group had higher median blood loss (875 mL vs. 550 mL, P = 0<0.01), but no differences in mortality, complication rates, length of stay, or readmission rates were found in a median follow-up of 29 months. Overall survival rates were similar. Predictors of mortality on multivariate analysis included increasing histological grade (P = 0.01), positive lymph nodes (P = 0.01), and increasing tumor size (P = 0.01), but not VR (P = 0.28). When evaluated by computed tomography scans within 6 months postoperatively, 97% of reconstructions remained patent.

CONCLUSIONS

The need for VR is not a contraindication to potentially curative resection in patients with pancreatic adenocarcinoma. Assistance of a vascular surgeon during VR may allow moderate-volume centers to achieve outcomes comparable with high-volume centers.

Comparison of outcomes and the use of multimodality therapy in young and elderly people undergoing surgical resection of pancreatic cancer

OBJECTIVES

To compare outcomes and the use of multimodality therapy in young and elderly people with pancreatic cancer undergoing surgical resection.

DESIGN

Retrospective, single-institution study.

SETTING

National Cancer Institute/National Comprehensive Cancer Network cancer center.

PARTICIPANTS

Two hundred three individuals who underwent pancreaticoduodenectomy for pancreatic adenocarcinoma at Duke University Medical Center comprised the study population. Participants were divided into three groups based on age (<65, n = 97; 65-74, n = 74; ≥75, N = 32).

MEASUREMENTS

Perioperative outcomes, the use of multimodality therapy, and overall survival of the different age groups were compared.

RESULTS

Similar rates of perioperative mortality and morbidity were observed in all age groups, but elderly adults were more likely to be discharged to a rehabilitation or skilled nursing facility. A similar proportion of participants received neoadjuvant therapy, but a smaller proportion of elderly participants received adjuvant therapy. Overall survival was similar between the age groups. Predictors of poorer overall survival included coronary artery disease, positive resection margin, and less-differentiated tumor histology. Treatment with neoadjuvant and adjuvant therapy were predictors of better overall survival.

CONCLUSION

Carefully selected elderly individuals experience similar perioperative outcomes and overall survival to those of younger individuals after resection of pancreatic cancer. There appears to be a significant disparity in the use of adjuvant therapy between young and elderly individuals.

Aptamers: potential applications to pancreatic cancer therapy

There is an unquestionable need for more effective therapies for pancreatic cancer. Aptamers are single-stranded DNA or RNA oligonucleotide ligands whose 3-dimensional structures are dictated by their sequences. Aptamers have been generated against numerous purified protein targets using an iterative in vitro selection technique known as Systematic Evolution of Ligands by EXponential enrichment (SELEX). Several biochemical properties make them attractive tools for use in an array of biological research applications and as potential pharmacologic agents. Isolated aptamers may directly affect target protein function, or they may also be modified for use as delivery agents for other therapeutic cargo or as imaging agents. More complex selections, using whole cancer cells or tumor tissue, may simultaneously identify novel or unexpected targets and aptamers to inhibit them. This review summarizes recent advances in the field of aptamers and discusses aptamer targets that have relevance to pancreatic cancer.

A decision model of therapy for potentially resectable pancreatic cancer

BACKGROUND

Optimal treatment for potentially resectable pancreatic cancer is controversial. Resection is considered the only curative treatment, but neoadjuvant chemoradiotherapy may offer significant advantages.

MATERIALS AND METHODS

We developed a decision model for potentially resectable pancreatic cancer. Initial therapeutic choices were surgery, neoadjuvant chemoradiotherapy, or no treatment; subsequent decisions offered a second intervention if not prohibited by complications or death. Payoffs were calculated as the median expected survival. We gathered evidence for this model through a comprehensive MEDLINE search. One-way sensitivity analyses were performed.

RESULTS

Neoadjuvant chemoradiation is favored over initial surgery, with expected values of 18.6 and 17.7 mo, respectively. The decision is sensitive to the probabilities of treatment mortality and tumor resectability. Threshold probabilities are 7.0% mortality of neoadjuvant chemoradiotherapy, 69.2% resectability on imaging after neoadjuvant therapy, and 73.7% resectability at exploration after neoadjuvant therapy, 92.2% resectability at initial resection, and 9.9% surgical mortality following chemoradiotherapy. The decision is sensitive to the utility of time spent in chemoradiotherapy, with surgery favored for utilities less than 0.3 and -0.8, for uncomplicated and complicated chemoradiotherapy, respectively.

CONCLUSIONS

The ideal treatment for potentially resectable pancreatic cancer remains controversial, but recent evidence supports a slight benefit for neoadjuvant therapy. Our model shows that the decision is sensitive to the probability of tumor resectability and chemoradiation mortality, but not to rates of other treatment complications. With minimal benefit of one treatment over another based on survival alone, patient preferences will likely play an important role in determining best treatment.

Abstract 2817: An RNA aptamer is a potential biomarker for pancreatic cancer

Introduction: The symptoms of pancreatic cancer are usually non-specific and late. Existing tumor markers (such as CA19-9 and CEA) are neither sensitive nor specific enough to serve as useful screening tests. Tools for earlier detection could increase the proportion of patients who are cured with surgical resection.

Aptamers are oligonucleotide ligands that are identified from large libraries of RNA or DNA molecules using an iterative selection process known as SELEX (Systematic Evolution of Ligands by Exponential Enrichment). Aptamers bind their specific targets with high affinity and specificity and can be used for the dual purpose of identifying novel biomarkers and detecting them in biological specimens.

Methods: In order to select for aptamers against molecules that are selectively secreted by cancerous cells but not by normal cells, “positive/negative” SELEX was performed using the conditioned media (the “secretome”) of the MiaPaCa2 human pancreatic ductal adenocarcinoma cell line (positive selection) and the immortalized, non-cancerous human pancreatic ductal cell line HPDE (negative selection). Standard radioactive filter-based binding assays were used to measure binding.

Results/Conclusion: We have successfully selected several nuclease resistant (2′-fluoro-modified) RNA aptamers that differentially bind the secretome of pancreatic cancer cells compared to non-cancerous cells. One of the aptamers (M9-5) binds pancreatic cancer patient sera with high affinity compared to control sera collected from healthy donors. So far, the aptamer has demonstrated specific binding in 20 of 22 patients with histologically-proven pancreatic cancer and none of 20 healthy donors. In addition, paired serum samples obtained from two patients pre- and post-chemoradiation therapy and one patient pre- and two months post-resection have demonstrated a decrease in M9-5 binding with decreased tumor burden. Notably, the serum CA19-9 and CEA levels in several of these patients were normal, indicating that our biomarker might be more sensitive than these existing serum biomarkers for pancreatic cancer. M9-5 binding to the MiaPaCa2 “secretome” is sensitive to Proteinase K treatment indicating that the aptamer target is a protein. Currently, we are using a biotinylated version of the aptamer to affinity purify the target and identify it by mass-spectrometric techniques.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2817. doi:10.1158/1538-7445.AM2011-2817

Aptamer applications for targeted cancer therapy

Aptamers are single-stranded DNA or RNA oligonucleotides that assume specific 3D structures and bind to target molecules with high affinity. The unique specificity of aptamers has made them attractive agents for targeted cancer therapy. Aptamers have been developed against a variety of cancer targets, including extracellular ligands and cell surface proteins. In addition, aptamers have been incorporated into novel constructs involving siRNAs, chemotherapeutic agents, cell toxins and nanoparticles, in which they function as delivery agents for therapeutic cargo. In this article, we review recent developments in the use of aptamers for targeted cancer therapy, particularly focusing on novel applications of aptamers targeting the cell surface.

Isolation and Characterization of a Protective Antigen-Containing Particle from Culture Supernatant Fluids of Erysipelothrix rhusiopathiae

The mouse-protective activity of Erysipelothrix rhusiopathiae culture supernatant fluids exists in a polydisperse form, ranging in density from aggregates which sediment at 10,000 x g for 3 hr to soluble units which will not sediment at 198,000 x g for 12 hr. A partially purified protective antigen has been isolated from the aggregates sedimented from a concentrate of the culture supernatant fluid at 20,000 x g for 3 hr. These aggregates contained the major protective antigen or antigens of E. rhusiopathiae, since, in addition to inducing active immunity, they adsorbed essentially all of the passively protecting antibody from rabbit antiserum produced by immunization with whole culture. The protective activity in these aggregates was destroyed by trypsin and greatly diminished by muramidase and heating at 64 C, but was not affected by lipase or ribonuclease.

Solubilization and Characterization of a Protective Antigen of Erysipelothrix rhusiopathiae

A particulate fraction of Erysipelothrix rhusiopathiae cultures has been subjected to butanol extraction and treatment with surface-active agents in an attempt to solubilize a protective antigen. The particulate fraction was partitioned into the butanol layer but was not solubilized. Only sodium dodecyl sulfate solubilized the particles. The soluble protective activity was not sedimented by centrifugation at 198,000 x g for 12 hr but was excluded by Sephadex G-200. Immunodiffusion studies of the soluble fraction demonstrated eight antigens, five of horse serum origin and three of E. rhusiopathiae origin. Ultracentrifugation indicated that spontaneous reaggregation occurred after removal of the sodium dodecyl sulfate. Analytical ultracentrifugation showed that 90% of the sodium dodecyl sulfatetreated material migrated as a single homogeneous 3.5S component. The physical and biological characteristics of the protective activity suggest that the protective antigen is a glyco-lipoprotein.

Predictors of a true complete response among disappearing liver metastases from colorectal cancer after chemotherapy

BACKGROUND

During chemotherapy, some colorectal liver metastases (LMs) disappear on serial imaging. This disappearance may represent a complete response (CR) or a reduction in the sensitivity of imaging during chemotherapy. The objective of the current study was to determine the fate of disappearing LMs (DLMs) and the factors that predict a true CR.

METHODS

Between 2000 and 2003, 435 patients who were evaluated by hepatobiliary surgeons received chemotherapy before they were considered for resection. Inclusion criteria were <12 LMs before chemotherapy, at least 1 DLM on a computed tomography (CT) scan, and either surgical resection or 1 year of clinical follow-up after the disappearance of LMs. A true CR was defined as either a pathologic CR (no tumor detected in the resection specimen) or a durable clinical CR (did not reappear on follow-up imaging). Clinical and pathologic factors were analyzed to identify those associated with a true CR.

RESULTS

During chemotherapy, 39 patients (9%) had a total of 118 DLMs on follow-up CT scans. Sixty-eight DLMs were resected, and 50 were followed clinically. Overall, 75 DLMs (64%) were true CRs, including 44 pathologic CRs and 31 durable clinical CRs. On multivariate analysis, the use of hepatic arterial infusion (HAI) chemotherapy (odds ratio [OR], 6.2; P = .02), the inability to observe the DLM on a magnetic resonance image (OR, 4.7; P = .005), and normalization of serum carcinoembryonic antigen levels (OR, 4.6; P = .006) were associated independently with a true CR.

CONCLUSIONS

Approximately 66% of DLMs represented a true CR according to assessment by resection or radiologic follow-up. Predictive factors may help to stratify patients who are likely to harbor residual disease.

Papillary intralymphatic angioendothelioma of the thigh: A case report and review of the literature

The term angiosarcoma, encompasses several neoplasms, all of which exhibit a malignant process derived from endothelial cells of the vessels. The most common form of angiosarcoma is highly aggressive, often fatal, and usually affects the head and neck region of elderly white men. Other low-grade forms of angiosarcoma, including papillary intralymphatic angioendothelioma, also known as Dabska tumor, are less invasive, affect a wider age range, and offer a better prognosis. There are several predisposing factors that increase the risk of angiosarcoma and include chronic lymphedema of the extremities, preexisting vascular lesions, and prior radiation, often as therapy for other malignancies. We report an unusual case of a very small, low-grade angiosarcoma on the thigh of an adult female with no known predisposing risk factors.

Notch promotes radioresistance of glioma stem cells

Radiotherapy represents the most effective nonsurgical treatments for gliomas. However, gliomas are highly radioresistant and recurrence is nearly universal. Results from our laboratory and other groups suggest that cancer stem cells contribute to radioresistance in gliomas and breast cancers. The Notch pathway is critically implicated in stem cell fate determination and cancer. In this study, we show that inhibition of Notch pathway with gamma-secretase inhibitors (GSIs) renders the glioma stem cells more sensitive to radiation at clinically relevant doses. GSIs enhance radiation-induced cell death and impair clonogenic survival of glioma stem cells but not non-stem glioma cells. Expression of the constitutively active intracellular domains of Notch1 or Notch2 protect glioma stem cells against radiation. Notch inhibition with GSIs does not alter the DNA damage response of glioma stem cells after radiation but rather reduces Akt activity and Mcl-1 levels. Finally, knockdown of Notch1 or Notch2 sensitizes glioma stem cells to radiation and impairs xenograft tumor formation. Taken together, our results suggest a critical role of Notch signaling to regulate radioresistance of glioma stem cells. Inhibition of Notch signaling holds promise to improve the efficiency of current radiotherapy in glioma treatment.

Percutaneous abscess drainage in patients with perforated acute appendicitis: effectiveness, safety, and prediction of outcome

OBJECTIVE

The purposes of this study were to retrospectively investigate the effectiveness and safety of CT-guided percutaneous drainage in the treatment of patients with acute appendicitis complicated by perforation and to identify CT findings and procedure-related factors predictive of clinical and procedure outcome.

MATERIALS AND METHODS

From March 2005 through December 2008, 41 consecutively registered patients (24 men, 17 women; age range, 18-75 years) underwent CT-guided percutaneous drainage for the management of acute appendicitis complicated by perforation and abscess. Three board-certified radiologists independently reviewed preprocedure CT images. Patients were assigned to one of three risk categories on the basis of the CT findings. Success and failure of percutaneous drainage were defined on a per-patient (i.e., clinical outcome) and per-procedure (i.e., technical outcome) basis. Immediate, periprocedure, and delayed complications were recorded. The association between candidate predictive variables, including demographic characteristics, preprocedure CT findings, and procedure-related factors and clinical or technical outcome was assessed with logistic regression models.

RESULTS

Fifty-two CT-guided procedures were performed on 41 patients. Percutaneous drainage had clinical and technical success rates of 90% (37 of 41 patients, 47 of 52 procedures) with no procedure-related complications. In seven patients (19%) clinical success required repeated drainage procedures. A large, poorly defined periappendiceal abscess and an extraluminal appendicolith on preprocedure CT images were independent predictors of clinical failure of percutaneous drainage.

CONCLUSION

CT-guided percutaneous drainage is both effective and safe in the treatment of patients with acute appendicitis complicated by perforation and abscess. The clinical and technical success rates are high.

Defining criteria for selective operative management of pancreatic cystic lesions: does size really matter?

INTRODUCTION

Proposed criteria for resection of pancreatic cystic lesions have included symptoms, size (>3 cm), and suspicious features by endoscopic ultrasound (EUS). The objective of this study was to evaluate risk factors for malignancy in a large series of patients undergoing resection of suspected pancreatic cystic neoplasms.

METHODS

Medical records of patients selected for resection of pancreatic cystic lesions at Duke University Medical Center from 2000 to 2008 were reviewed. Lesions with solid components on cross-sectional imaging were excluded. Malignancy was defined as invasive or in situ carcinoma.

RESULTS

After review, 101 patients were confirmed to have undergone resection for suspected cystic neoplasms of the pancreas. Preoperative EUS was performed in 71 patients. Sixteen patients (16%) had malignant lesions (preoperative size 1.5-5.9 cm). There was no clear association between size and malignancy. Male gender, biliary ductal dilatation (BDD), pancreatic ductal dilatation (PDD), and suspicious cytology (but not age, symptoms, or size) were associated with increased risk of malignancy. When factors available for all patients were incorporated into a multivariate model, only BDD and PDD were independent risk factors for malignancy. Only one patient with malignancy had neither BDD nor PDD but did have solid components by EUS.

CONCLUSIONS

In patients selected for resection, size was not an independent risk factor for malignancy. While size might be appropriate for stratification of asymptomatic patients with simple cysts, size should not be used as a selection criterion for patients who have cysts with solid components or with associated BDD or PDD.

Pancreaticoduodenectomy: frequency and outcome of post-operative imaging-guided percutaneous drainage

BACKGROUND

To study the frequency and outcomes of percutaneous imaging-guided drainage following pancreaticoduodenectomy and to assess if fluid collection location correlates with pancreatic duct leak.

METHODS

IRB approval was obtained. Three hundred and seventy-three subjects (age 21-84 years) who underwent pancreaticoduodenectomy were included in this retrospective study. Eighty-three of these subjects underwent post-operative imaging-guided drainage (CT 77; US 6). Medical and imaging records were reviewed. Procedural details including collection location, size, catheter size, drain duration, fluid type, fluid chemistry, and fluid culture were recorded. Collection location was correlated with fluid amylase.

RESULTS

The frequency of imaging-guided percutaneous drainage following Whipple was 22.2%. The immediate technical and overall success rates for fluid collection drainage were 97.6% and 79.6%, respectively. Rate of complication was 4.8% (4/83). 74.7% (62/83) of fluid collections were proven abscesses, and 61.4% (51/83) were complicated by pancreatic fistula. Collections near the pancreatic resection site were more likely to have elevated fluid amylase.

CONCLUSION

Approximately one-fifth of subjects requires percutaneous drainage following pancreaticoduodenectomy. Percutaneous imaging-guided drainage is an effective means of managing post-pancreaticoduodenectomy fluid collections. Collections near the pancreas resection site often have a pancreatic duct leak.

Evaluation of peri-operative chemotherapy using a prognostic nomogram for survival after resection of colorectal liver metastases

INTRODUCTION

Nomograms are statistical tools designed to predict outcomes. This study evaluates the effects of peri-operative chemotherapy on the accuracy of a prognostic nomogram for disease-specific survival (DSS) after resection of colorectal liver metastases (CRLM) established at Memorial-Sloan Kettering Cancer Center (MSKCC).

METHODS

An external cohort of 203 patients who underwent resection of CRLM between 1996 and 2006 was used to assess the nomogram.

RESULTS

After median follow-up of 30.4 months (range 0.33-150), Kaplan-Meier (KM) estimates for 3-, 5- and 8-year post-resection DSS were 56%, 41%, and 32%, respectively; similar to nomogram-predicted probabilities for DSS. The concordance index for the nomogram was higher (0.602) than for the Fong colorectal risk score (CRS; 0.533). KM DSS was longer for patients (n= 50) treated with at least 6 months of peri-operative irinotecan or oxaliplatin compared with all other patients (median 66 vs. 40 months, P= 0.06). KM DSS was greater than nomogram predicted DSS for treated patients and less than nomogram predicted DSS for all other patients.

CONCLUSIONS

The CRLM nomogram was validated by an external cohort and more accurately predicted post-resection survival than the commonly used CRS. Differences in observed and nomogram-predicted survival may reflect the effect of treatment factors, such as peri-operative chemotherapy.

Timing of multimodality therapy for resectable synchronous colorectal liver metastases: a retrospective multi-institutional analysis

The optimal timing of chemotherapy relative to resection of synchronous colorectal liver metastases (SCRLM) is not known. The objective of this retrospective multi-institutional study was to assess the influence of chemotherapy administered before and after hepatic resection on long-term outcomes among patients with initially resectable SCRLM treated from 1995 to 2005. Clinicopathologic data, treatments, and long-term outcomes from patients with initially resectable SCRLM who underwent partial hepatectomy at three hepatobiliary centers were reviewed. Four hundred ninety-nine consecutive patients underwent resection; 297 (59.5%) and 264 (52.9%) were treated with chemotherapy before and after resection. Chemotherapy strategies included pre-hepatectomy alone (n = 148, 24.7%), post-hepatectomy alone (n = 115, 23.0%), perioperative (n = 149, 29.0%), and no chemotherapy (n = 87, 17.4%). Male gender (p = 0.0029, HR = 1.41 [1.12-1.77]), node-positive primary tumor (p = 0.0046, HR = 1.40 [1.11-1.77]), four or more SCRLM (p = 0.0005, HR = 1.65 [1.24-2.18]), and post-hepatectomy chemotherapy treatment for 6 months or longer (p = 0.039, HR = 0.75 [0.57-0.99]) were associated with recurrence-free survival after discovery of SCRLM. Carcinoembryonic antigen >200 ng/ml (p = 0.0003, HR = 2.33 [1.48-3.69]), extrahepatic metastatic disease (p = 0.0025, HR = 2.34 [1.35-4.05]), four or more SCRLM (p = 0.033, HR = 1.43 [1.03-2.00]), and post-hepatectomy chemotherapy treatment for 2 months or longer (p < 0.0001, HR = 0.59 [0.45-0.76]) were associated with overall survival. Pre-hepatectomy chemotherapy was not associated with recurrence-free or overall survival. Patients treated with perioperative chemotherapy had similar outcomes as patients treated with post-hepatectomy chemotherapy only. We conclude that chemotherapy administered after but not before resection of SCRLM was associated with improved recurrence-free and overall survival. However, prospective randomized trials are needed to determine the optimal timing of chemotherapy.

The Role of Aggressive Regional Therapy for Colorectal Liver Metastases

Surgical resection is the most effective treatment modality for liver metastases from colorectal cancer. However, most patients with liver metastases are not candidates for resection due to extensive intrahepatic disease. Approximately one-half of the patients who are able to undergo resection will eventually recur within the remnant liver. Hepatic arterial infusion (HAI) chemotherapy takes advantage of the arterial blood supply of colorectal liver metastases to increase tumor exposure to chemotherapy while minimizing systemic toxicity. HAI chemotherapy has been utilized in patients with unresectable disease in the neoadjuvant setting in an effort to convert them to resectability as well as in patients with resectable disease in the adjuvant setting in an effort to prevent recurrence. This article reviews the roles of HAI chemotherapy in an aggressive approach toward colorectal liver metastases.

The development and testing of aptamers for cancer

Aptamers are single-stranded DNA or RNA oligonucleotides that have specific three-dimensional structures and bind to target molecules. Several unique properties of aptamers, including high binding specificity, low immunogenicity, structural stability and ease of synthesis, have made aptamers promising agents for directed therapy against cancer targets. Aptamers with anti-neoplastic activity against extracellular, cell membrane and intracellular targets have been developed. Aptamers also have been incorporated into novel constructs as tools for delivering therapeutic agents. This review discusses the most recent advances in the application of aptamer technology for cancer therapy.

Crystal structure of an RNA aptamer bound to thrombin

Aptamers, an emerging class of therapeutics, are DNA or RNA molecules that are selected to bind molecular targets that range from small organic compounds to large proteins. All of the determined structures of aptamers in complex with small molecule targets show that aptamers cage such ligands. In structures of aptamers in complex with proteins that naturally bind nucleic acid, the aptamers occupy the nucleic acid binding site and often mimic the natural interactions. Here we present a crystal structure of an RNA aptamer bound to human thrombin, a protein that does not naturally bind nucleic acid, at 1.9 A resolution. The aptamer, which adheres to thrombin at the binding site for heparin, presents an extended molecular surface that is complementary to the protein. Protein recognition involves the stacking of single-stranded adenine bases at the core of the tertiary fold with arginine side chains. These results exemplify how RNA aptamers can fold into intricate conformations that allow them to interact closely with extended surfaces on non-RNA binding proteins.

A nuclease-resistant RNA aptamer specifically inhibits angiopoietin-1-mediated Tie2 activation and function

Tie2 is a receptor tyrosine kinase that is expressed predominantly in the endothelium and plays key roles in both physiological and pathological angiogenesis. The ligands for Tie2, the angiopoietins (Ang), perform opposing functions in vascular maintenance and angiogenesis; Ang1 regulates vascular quiescence, while Ang2 is thought to promote vascular destabilization and facilitate angiogenesis. However, the mechanisms responsible for these differences are not understood. To begin to elucidate the molecular differences between the angiopoietins, we previously developed a specific RNA aptamer inhibitor of Ang2. Here, we used the same iterative in vitro selection process, termed SELEX (Systematic Evolution of Ligands by EXponential enrichment), to screen a library of 2'-fluoro-modified ribonucleotides for Ang1-binding aptamers. After nine rounds of selection, we identified a single clone, ANG9-4, that bound with high affinity to human Ang1 (K ( d ) 2.8 nM) but not Ang2 (K ( d ) > 1 microM), demonstrating specificity for Ang1. ANG9-4 blocked Ang1-mediated Tie2 phosphorylation and downstream Akt activation. Moreover, ANG9-4 inhibited Ang1-induced endothelial cell survival. Together, these findings demonstrate the feasibility of developing an Ang1-inhibitory aptamer. ANG9-4 and its derivatives may provide useful tools for elucidating the biology of Ang1 and for treating certain angiogenic diseases.

Rates and patterns of recurrence for percutaneous radiofrequency ablation and open wedge resection for solitary colorectal liver metastasis

INTRODUCTION

The purpose of this study was to compare rates and patterns of disease progression following percutaneous, image-guided radiofrequency ablation (RFA) and nonanatomic wedge resection for solitary colorectal liver metastases.

METHODS

We identified 30 patients who underwent nonanatomic wedge resection for solitary liver metastases and 22 patients who underwent percutaneous RFA because of prior major hepatectomy (50%), major medical comorbidities (41%), or relative unresectability (9%). Serial imaging studies were retrospectively reviewed for evidence of local tumor progression.

RESULTS

Patients in the RFA group were more likely to have undergone prior liver resection, to have a disease-free interval greater than 1 year, and to have had an abnormal carcinoembryonic antigen (CEA) level before treatment. Two-year local tumor progression-free survival (PFS) was 88% in the Wedge group and 41% in the RFA group. Two patients in the RFA group underwent re-ablation, and two patients underwent resection to improve the 2-year local tumor disease-free survival to 55%. Approximately 30% of patients in each group presented with distant metastasis as a component of their first recurrence. Median overall survival from the time of resection was 80 months in the Wedge group vs 31 months in the RFA group. However, overall survival from the time of treatment of the colorectal primary was not significantly different between the two groups.

CONCLUSIONS

Local tumor progression is common after percutaneous RFA. Surgical resection remains the gold standard treatment for patients who are candidates for resection. For patients who are poor candidates for resection, RFA may help to manage local disease, but close follow-up and retreatment are necessary to achieve optimal results.

Fixation of Vancouver B1 peri-prosthetic fractures by broad metal plates without the application of strut allografts

The use of allograft struts and cerclage wire, possibly augmented by plate fixation, for the treatment of Vancouver type-B1 peri-prosthetic fractures around a total hip replacement has been strongly advocated. We examined our results using plate fixation without allograft struts and compared them with the results of the use of struts alone or when combined with plate fixation. Of 20 consecutive patients with type-B1 fractures treated by open reduction and plate fixation, 19 were available for follow-up. The fractures healed in 18 patients with a mean time to weight-bearing of ten weeks (4 to 19). There were no cases of infection or malunion. Nonunion occurred in one patient and required a second plate fixation to achieve union.

Safe, cost-effective treatment of Vancouver type-B1 fractures can be performed by plate fixation without the addition of cortical struts. This procedure may allow earlier weight-bearing than allograft strut fixation alone.

Evaluation of preoperative therapy for pancreatic cancer using a prognostic nomogram

BACKGROUND

Theoretical benefits of preoperative chemoradiation therapy (preop CRT) for pancreatic cancer include improved efficacy, resectability, and patient selection. The goal of this study was to evaluate the applicability of a nomogram, which was developed for patients undergoing resection without preop CRT and which incorporates several post-resection pathological factors, to a population of patients who received preop CRT prior to resection.

METHODS

From 1994 to 2004, 82 patients with biopsy-proven, radiographically localized adenocarcinoma of the pancreatic head underwent preop CRT followed by pancreaticoduodenectomy (PD); 50 concurrent patients underwent PD without preop CRT. Mean nomogram-predicted disease-specific survival (DSS) rates were compared with observed DSS rates from the time of resection.

RESULTS

Despite having more locally advanced tumors on initial staging (21 vs. 8%; P < .05), patients who received preop CRT had smaller resected tumors (mean 2.3 vs. 3.1 cm; P < .01), were less likely to have T3 tumors (54 vs. 80%, P < .01), were less likely to have positive lymph nodes (29 vs. 58%, P < .01), and had fewer positive lymph nodes (mean .4 vs. 1.9, P < .01), all factors that imply treatment effect and favorably impact on nomogram-predicted DSS. Observed DSS was similar to predicted DSS in both groups.

CONCLUSIONS

The similarity in observed and predicted DSS following resection in patients who received preop CRT suggests that the effects of preop CRT-whether treatment, selection, or no effect-are reflected by the nomogram. The ability of the nomogram to evaluate the effects of preop CRT on survival is limited by the potential effects of preop CRT on factors within the nomogram.

Energy input and response from prompt and early optical afterglow emission in γ-ray bursts

The taxonomy of optical emission detected during the critical first few minutes after the onset of a gamma-ray burst (GRB) defines two broad classes: prompt optical emission correlated with prompt gamma-ray emission, and early optical afterglow emission uncorrelated with the gamma-ray emission. The standard theoretical interpretation attributes prompt emission to internal shocks in the ultra-relativistic outflow generated by the internal engine; early afterglow emission is attributed to shocks generated by interaction with the surrounding medium. Here we report on observations of a bright GRB that, for the first time, clearly show the temporal relationship and relative strength of the two optical components. The observations indicate that early afterglow emission can be understood as reverberation of the energy input measured by prompt emission. Measurements of the early afterglow reverberations therefore probe the structure of the environment around the burst, whereas the subsequent response to late-time impulsive energy releases reveals how earlier flaring episodes have altered the jet and environment parameters. Many GRBs are generated by the death of massive stars that were born and died before the Universe was ten per cent of its current age, so GRB afterglow reverberations provide clues about the environments around some of the first stars.

Effect of neoadjuvant chemoradiation on operative mortality and morbidity for pancreaticoduodenectomy

BACKGROUND

Neoadjuvant chemoradiotherapy (neo-CRT) is being used with increasing frequency for periampullary tumors, but how it alters the complication rate of pancreaticoduodenectomy (PD) is unclear.

METHODS

A retrospective analysis was conducted of 79 patients with periampullary malignancies who received 5-fluorouracil-based neo-CRT followed by PD.

RESULTS

There was no difference in mortality between PD after neo-CRT (3.8%) and conventional PD for either malignant (4.5%) or benign (2.2%) disease. Focusing only on patients with malignancy, the neo-CRT group had a significantly lower pancreatic leak rate than the conventional group (10% vs. 43%; P < .001). Intra-abdominal abscesses were less common in the neo-CRT group (8.8% vs. 21%; P = .019), and there was one (1.2%) amylase-rich abscess in neo-CRT group, compared with eight (12%) in the conventional group. In addition, two patients in the conventional group died of leak-associated sepsis, compared with none in the neo-CRT group. Multivariate analysis revealed that neoadjuvant chemoradiation (odds ratio, .15) was the most significant factor associated with a reduced risk of pancreatic leak.

CONCLUSIONS

Neo-CRT does not increase the mortality or morbidity of PD. In contrast, neo-CRT was associated with a marked reduction in the incidence of pancreatic leak, as well as leak-associated morbidity and mortality.

A link between prompt optical and prompt γ-ray emission in γ-ray bursts

The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium.

Significance of histological response to preoperative chemoradiotherapy for pancreatic cancer

BACKGROUND

Neoadjuvant (preoperative) chemoradiotherapy (CRT) for pancreatic cancer offers theoretical advantages over the standard approach of surgery followed by adjuvant CRT. We hypothesized that histological responses to CRT would be significant prognostic factors in patients undergoing neoadjuvant CRT followed by resection.

METHODS

Since 1994, 193 patients with biopsy-proven pancreatic adenocarcinoma have completed neoadjuvant CRT, and 70 patients have undergone resection. Specimens were retrospectively examined by an individual pathologist for histological responses (tumor necrosis, tumor fibrosis, and residual tumor load) and immunohistochemical staining for p53 and epidermal growth factor receptor. Factors influencing overall survival were analyzed with the Kaplan-Meier (univariate) and Cox proportional hazards (multivariate) methods.

RESULTS

The estimated overall survival (median +/- SE) in the entire group of patients undergoing resection was 23 +/- 4.2 months, with an estimated 3-year survival of 37% +/- 6.6% and a median follow-up of 28 months. Complete histological responses occurred in 6% of patients. Overexpression of p53 was more common in patients with large residual tumor loads. Tumor necrosis was an independent negative prognostic factor, as were positive lymph nodes, a large residual tumor load, and poor tumor differentiation.

CONCLUSIONS

Histological response to neoadjuvant CRT--as measured by residual tumor load--may be useful as a surrogate marker for treatment efficacy. Characterization of the tumor cells that survive neoadjuvant CRT may help us to identify new or more appropriate targets for systemic therapy.

Modeling the environmental fate of manganese from methylcyclopentadienyl manganese tricarbonyl in urban landscapes

The environmental impacts of gasoline additives such as lead (Pb) and Methyl Tertiary Butyl Ether (MTBE) are well documented, leading to the phasing out of these additives. In contrast, little is known about the health and environmental impacts of potential replacement chemicals such as Methylcyclopentadienyl Manganese Tricarbonyl (MMT). The combustion of MMT in gasoline leads to the formation of MnPO4 and MnSO4 and MMT is considered a recent source of inorganic Mn in urban landscapes particularly in high traffic areas. The main objective of this study is to estimate the automotive deposition of Mn from MMT relative to the traffic volume at sites near a major highway in the Greater Toronto Area of Canada, where MMT is currently being used. Manganese emission levels were estimated for two sites that varied according to Annual Average Daily Traffic (AADT) density, fuel consumption, distance traveled by automobiles, and Mn concentration (mg l(-1)) in gasoline. Multiple regression analysis was used to predict the AADT volume from year 2002-2010. Comparison of the mass balance between the ANOVA means of 15% Mn emitted from the automobile tailpipes at 10, and 18 mg of Mn l(-1) in gasoline was conducted for both study sites. The percentage difference between the Mn input at the selected concentrations of Mn in gasoline and output into surface soil were found to be 99% significant for both sites. Thus the predicted 15% tailpipe emission levels for 10 mg of Mn l(-1) of gasoline used in automobiles, which represented 1290.03 g/year for site 1 and 555.94 g/year for site 2, will add 5.73 and 2.47 mg/kg of Mn annually, respectively. These input levels are considered negligible when compared to the natural abundance of Mn in soil. Based on these data, it could take more than 95-256 years of continuous MMT usage in the region to double the content of Mn in surface soils at the respective sites.

The role of chemoradiation therapy in locally advanced pancreatic cancer

The majority of patients with pancreatic cancer present with disease that is unresectable due to local invasion. This article reviews the evidence (or lack thereof) that chemoradiation therapy (CRT) helps these patients in four areas: survival, tumor downstaging, palliation of obstructive symptoms, and pain control. We believe that CRT allows a small percentage of patients with locally advanced disease to undergo potentially curative resection while providing effective palliative treatment.

Antidote-mediated control of an anticoagulant aptamer in vivo

Patient safety and treatment outcome could be improved if physicians could rapidly control the activity of therapeutic agents in their patients. Antidote control is the safest way to regulate drug activity, because unlike rapidly clearing drugs, control of the drug activity is independent of underlying patient physiology and co-morbidities. Until recently, however, there was no general method to discover antidote-controlled drugs. Here we demonstrate that the activity and side effects of a specific class of drugs, called aptamers, can be controlled by matched antidotes in vivo. The drug, an anticoagulant aptamer, systemically induces anticoagulation in pigs and inhibits thrombosis in murine models. The antidote rapidly reverses anticoagulation engendered by the drug, and prevents drug-induced bleeding in surgically challenged animals. These results demonstrate that rationally designed drug-antidote pairs can be generated to provide control over drug activities in animals.

Neoadjuvant therapy for pancreatic cancer: the Duke experience

The advantages of neoadjuvant (preoperative) chemoradiation therapy for pancreatic cancer include the assurance that all resected patients receive multimodality therapy; the opportunity for patients with occult metastatic disease to manifest themselves; and the potential to improve resectability. Since 1994, Duke University Medical Center has treated over 180 patients with localized pancreatic cancer using neoadjuvant 5-fluorouracil (5FU)-based chemoradiation therapy (CRT). Approximately 20% of patients demonstrate distant disease progression during CRT and avoid the morbidity of laparotomy. Almost 20% of locally advanced tumors on initial-staging CT can be resected following CRT. Patients who have successfully undergone resection have experienced favorable survival with an estimated 5-year survival rate of 36%. This article reviews the authors' experience and the lessons learned from it.

RNA aptamer to thrombin binds anion-binding exosite-2 and alters protease inhibition by heparin-binding serpins

We studied the RNA aptamer Toggle-25/thrombin interaction during inhibition by antithrombin (AT), heparin cofactor II (HCII) and protein C inhibitor (PCI). Thrombin inhibition was reduced 3-fold by Toggle-25 for AT and HCII, but it was slightly enhanced for PCI. In the presence of glycosaminoglycans, AT and PCI had significantly reduced thrombin inhibition with Toggle-25, but it was only reduced 3-fold for HCII. This suggested that the primary effect of aptamer binding was through the heparin-binding site of thrombin, anion-binding exosite-2 (exosite-2). We localized the Toggle-25 binding site to Arg 98, Glu 169, Lys 174, Asp 175, Arg 245, and Lys 248 of exosite-2. We conclude that a RNA aptamer to thrombin exosite-2 might provide an effective clinical reagent to control heparin's anticoagulant action.