Laparoscopic pancreatic resection.

Though initially slow to gain acceptance, the minimally invasive approach to pancreatic resection grew during the last decade and pancreatic operations such as the distal pancreatectomy and pancreatic enucleation are frequently performed laparoscopically. More complex operations such as the pancreaticoduodenectomy may also confer benefits with a minimally invasive approach but are less widely utilized. Though most research to date comparing open and laparoscopic pancreatectomy is retrospective, the current data suggest that compared with open, a laparoscopic procedure may afford postoperative benefits such as less blood loss, shorter hospital stay, and fewer wound complications. Regarding oncologic considerations, despite initial concerns, laparoscopic resection appears to be non-inferior to an open procedure in terms of lymph node retrieval, negative margin rates, and long-term survival. New technologies, such as robotics, are also gaining acceptance. Data show that while the laparoscopic approach incurs higher cost in the operating room, the resulting shorter hospital stay appears to be associated with an equivalent or lower overall cost. The minimally invasive approach to pancreatic resection can be safe and appropriate with significant patient benefits and oncologic non-inferiority based on existing data.

Low CHD5 expression activates the DNA damage response and predicts poor outcome in patients undergoing adjuvant therapy for resected pancreatic cancer.

The DNA damage response (DDR) promotes genome integrity and serves as a cancer barrier in precancerous lesions but paradoxically may promote cancer survival. Genes that activate the DDR when dysregulated could function as useful biomarkers for outcome in cancer patients. Using a siRNA screen in human pancreatic cancer cells, we identified the CHD5 tumor suppressor as a gene, which, when silenced, activates the DDR. We evaluated the relationship of CHD5 expression with DDR activation in human pancreatic cancer cells and the association of CHD5 expression in 80 patients with resected pancreatic adenocarcinoma (PAC) by immunohistochemical analysis with clinical outcome. CHD5 depletion and low CHD5 expression in human pancreatic cancer cells lead to increased H2AX-Ser139 and CHK2-Thr68 phosphorylation and accumulation into nuclear foci. On Kaplan-Meier log-rank survival analysis, patients with low CHD5 expression had a median recurrence-free survival (RFS) of 5.3 vs 15.4 months for patients with high CHD5 expression (P=0.03). In 59 patients receiving adjuvant chemotherapy, low CHD5 expression was associated with decreased RFS (4.5 vs 16.3 months; P=0.001) and overall survival (OS) (7.2 vs 21.6 months; P=0.003). On multivariate Cox regression analysis, low CHD5 expression remained associated with worse OS (HR: 3.187 (95% CI: 1.49-6.81); P=0.003) in patients undergoing adjuvant chemotherapy. Thus, low CHD5 expression activates the DDR and predicts for worse OS in patients with resected PAC receiving adjuvant chemotherapy. Our findings support a model in which dysregulated expression of tumor suppressor genes that induce DDR activation can be utilized as biomarkers for poor outcome.

A novel approach to cancer therapy using an oncolytic herpes virus to package amplicons containing cytokine genes.

There are two promising herpes viral-based anticancer strategies: one involves replication-defective viruses to transfer therapeutic transgenes, and the other involves replication-conditional oncolytic viruses, which selectively infect and destroy cancer cells directly. This study examines a novel dual herpesvirus preparation, which combines the immunostimulatory effects of amplicon-mediated IL2 expression with direct viral-induced oncolysis. The oncolytic virus G207 was used as the helper virus to package a herpes simplex virus (HSV)-amplicon vector carrying the gene IL2 (HSV-IL2), yielding a single preparation with two complementary modes of action. In vivo comparison was carried out in a syngeneic squamous cell carcinoma flank tumor model. We directly injected established tumors with HSV-IL2, G207, G207 mixed with HSV-IL2, or G207-packaged HSV-amplicon carrying the IL2 transgene (G207[IL2]). Significant inhibition of tumor growth was seen at 2 weeks in the G207[IL2]-treated tumors relative to controls (0.57+/-0.44 cm(3) versus 39.45+/-5.13 cm(3), P<0.00001), HSV-IL2 (20.97+/-4.60 cm(3)), and the G207 group (7.71+/-2.10 cm(3)). This unique use of a replication-conditional, oncolytic virus to package a replication-incompetent amplicon vector demonstrates impressive efficacy in vitro and in vivo, and avoids the theoretical concerns of recombination with reversion to wild type.

Using positron emission tomography with [(18)F]FDG to predict tumor behavior in experimental colorectal cancer.

This study investigates the relationship between FDG uptake as determined by positron emission tomography (PET) imaging and rates of tumor growth, cellular GLUT1 transporter density, and the activities of hexokinase and glucose-6-phosphatase in a solid tumor implant model. Five different human colorectal xenografts of different growth properties were implanted in athymic rats and evaluated by dynamic (18)F-FDG-PET. The phosphorylating and dephosphorylating activities of the key glycolytic enzymes, hexokinase and glucose-6-phosphatase, were measured in these tumor types by spectrophotometric assays and the expression of GLUT1 glucose transporter protein was determined by immunohistochemistry. Correlations among FDG accumulation, hexokinase activity, and tumor doubling time are reported in these colon xenografts. The results indicate that the activity of tumor hexokinase may be a marker of tumor growth rate that can be determined by (18)F-FDG-PET imaging. PET scanning may not only be a useful tool for staging patients for extent of disease, but may provide important prognostic information concerning the proliferative rates of malignancies.

Functional interaction between fluorodeoxyuridine-induced cellular alterations and replication of a ribonucleotide reductase-negative herpes simplex virus.

G207 is an oncolytic herpes simplex virus (HSV) which is attenuated by inactivation of viral ribonucleotide reductase (RR) and deletion of both gamma(1)34.5 genes. The cellular counterparts that can functionally substitute for viral RR and the carboxyl-terminal domain of ICP34.5 are cellular RR and the corresponding homologous domain of the growth arrest and DNA damage protein 34 (GADD34), respectively. Because the thymidylate synthetase (TS) inhibitor fluorodeoxyuridine (FUdR) can alter expression of cellular RR and GADD34, we examined the effect of FUdR on G207 bioactivity with the hypothesis that FUdR-induced cellular changes will alter viral proliferation and cytotoxicity. Replication of wild-type HSV-1 was impaired in the presence of 10 nM FUdR, whereas G207 demonstrated increased replication under the same conditions. Combined use of FUdR and G207 resulted in synergistic cytotoxicity. FUdR exposure caused elevation of RR activity at 10 and 100 nM, whereas GADD34 was induced only at 100 nM. The effect of enhanced viral replication by FUdR was suppressed by hydroxyurea, a known inhibitor of RR. These results demonstrate that the growth advantage of G207 in FUdR-treated cells is primarily based on an RR-dependent mechanism. Although our findings show that TS inhibition impairs viral replication, the FUdR-induced RR elevation may overcome this disadvantage, resulting in enhanced replication of G207. These data provide the cellular basis for the combined use of RR-negative HSV mutants and TS inhibitors in the treatment of cancer.

Relevance of Ki-67 antigen expression and K-ras mutation in colorectal liver metastases.

AIMS: The liver is a frequent site of metastases from colorectal cancer. While these lesions are potentially amenable to surgical resection, they are usually very aggressive, and recurrence is frequent. Mutations of the proto-oncogene K- ras are thought to impart a strong growth signal to tumour cells and are closely associated with the development of malignancies of the colon and rectum. Hepatic metastases from colorectal cancer have notably elevated proliferative rates. The present study was performed to investigate the relationship between proliferation or K- ras mutation and prognosis following curative resection of colorectal liver metastases. METHODS: Colorectal liver metastases from 41 patients undergoing curative hepatic resection were examined for proliferation status and presence of K- ras mutations. The proliferative activity was assessed by Ki-67 immunohistochemistry. DNA from the same tissue samples was screened for point mutations in codon 12 of the K- ras gene using a novel microplate-based allelic-specific hybridization assay. Ki-67 scores and K- ras status were then related with patient survival as determined through retrospective analysis. RESULTS: Median survival was 40 months. Patients with high Ki-67 scores (> or = 50%) had significantly shorter median survival compared with those with low scores (30 vs 44 months, log-rank P=0.02). A high Ki-67 score was an independent negative prognostic factor by multivariate regression analysis (relative risk=3.04, P=0.036). K- ras point mutations were detected in 6/41 patients (15%), but mutational status did not correlate with Ki-67 score or survival. CONCLUSIONS: These findings suggest that the tumour proliferative index is a useful predictor of aggressive tumour behaviour and an indicator of patient survival. The presence of K- ras mutations does not appear to correlate with tumour proliferation status or patient survival.

Effects of preexisting immunity on the response to herpes simplex-based oncolytic viral therapy.

Herpes simplex viruses (HSV) type 1 are the basis of a number of anticancer strategies that have proven efficacious in animal models. They are natural human pathogens and the majority of adults have anti-HSV immunity. The current study examined the effect of preexisting immunity on the response to herpes-based oncolytic viral treatment of hepatic metastatic cancer in a murine model designed to simulate a clinical approach likely to be utilized for nonneurological tumors. Specifically, the anticancer effects of NV1020 or G207, two multimutated HSV-1 oncolytic viruses, were tested in immunocompetent mice previously immunized with a wild-type herpes simplex type 1 virus. Mice were documented to have humoral as well as cell-mediated immunity to HSV-1. Tumor response to oncolytic therapy was not measurably abrogated by immunity to HSV at the doses tested. The influence of route of viral administration was also tested in models of regional hepatic arterial and intravenous therapy. Route of viral administration influenced efficacy, as virus delivered intravenously produced some detectable attenuation while hepatic arterial therapy remained unaffected. These results demonstrate that when given at appropriate doses and in reasonable proximity to tumor targets, HSV-based oncolytic therapy can still be expected to be effective treatment for patients with hepatic malignancies.

Combination gene therapy using multiple immunomodulatory genes transferred by a defective infectious single-cycle herpes virus in squamous cell cancer.

Herpes simplex type 2-defective infectious single-cycle (DISC) viruses are attenuated viruses that were originally produced as viral vaccines; however, these viruses are also efficient gene transfer vehicles. The main goals of this study were to examine determinants of the gene transfer by using DISC virus for squamous cancer and to evaluate the antitumoral efficacy of vaccination with tumor cells modified by DISC viruses carrying a combination of immunomodulatory genes (interleukin-2 (IL-2), granulocyte-macrophage colony-stimulating factor (GM-CSF), B7-1) in a model of squamous cell cancer (SCCVII) in C3H/HeJ mice. SCCVII cells transduced by DISC viruses (multiplicity of infection of 10) carrying the IL-2 or GM-CSF gene produced nanogram quantities of IL-2 or GM-CSF per 10(6) cells. Irradiated (5,000 cGy, 10,000 cGy) cells secreted levels of GM-CSF or IL-2 that were comparable with nonirradiated cells. In vivo vaccination using tumor cells transduced ex vivo with DISC-IL2 or DISC-GMCSF resulted in protection against subsequent tumor challenge (P < .01), with DISC-GMCSF-transduced, irradiated tumor cells showing the greatest effects (P < .001). Marked growth arrest also was noted in established tumors after direct injection of DISC-GMCSF (P < .001). These data demonstrate that (a) DISC virus is capable of efficient gene transfer, (b) GM-CSF-secreting genetically modified tumor vaccine protects against tumor cell challenge and suppresses tumor growth, and (c) intratumoral injection of DISC-GMCSF significantly suppresses the growth of established tumors. These results not only confirm clinically relevant gene transfer but also demonstrate that the gene transfer is an effective anti-cancer therapy.

Use of phosphorous-31 nuclear magnetic resonance spectroscopy to determine safe timing of chemotherapy after hepatic resection.

Liver resection induces accelerated growth of residual hepatic micrometastases. Adjuvant chemotherapy may improve outcome if administered early after resection but may prove lethal if initiated prior to completion of DNA synthesis in regenerating liver. This study investigates phosphorus-31 nuclear magnetic resonance ((31)P-NMR) as a noninvasive tool for measuring energy changes reflective of hepatic DNA synthesis and for predicting safe timing of chemotherapy after 70% hepatectomy. To evaluate metabolic changes in regenerating liver, quantitative three-dimensional (31)P-NMR was performed, using the technique of chemical shift imaging at various time points after 70% hepatectomy in adult male Fischer rats. Animals receiving a course of 2'-deoxy-5-fluorouridine (FUDR; 100 mg/kg, i.p. four times per day x 5), initiated at the time of operation, were also evaluated to observe the effects of chemotherapy on liver regeneration. Forty-eight hours after resection, hepatic nucleoside triphosphate (NTP), which reflects ATP content, fell 37% (P < 0.03) in animals undergoing hepatectomy alone. By contrast, animals receiving FUDR after hepatectomy demonstrated a mitigated NTP response, with a drop of only 17% (P = not significant), suggesting that interruption of DNA synthesis leads to a reduced consumption of ATP. Direct measures of DNA synthesis and nuclear proliferation were correlated with NMR findings. [(3)H]Thymidine incorporation and Ki67 immunohistochemistry were performed on liver samples from rats undergoing 70% hepatectomy with and without FUDR. Both [(3)H]thymidine incorporation and Ki67 expression were inhibited significantly at 48 h in animals receiving hepatectomy and FUDR, compared with those not treated with FUDR. To determine whether NMR changes could be used to identify safe timing of chemotherapy after hepatectomy, rats were treated with a 5-day course of FUDR initiated either prior to or after NMR changes normalized. Animals treated with FUDR at the point of NTP normalization (72 h) showed significantly improved survival over those that began treatment at operation (75 % versus 17 %; P = 0.0005, log rank test). FUDR inhibits hepatic DNA synthesis and influences mortality if administered too early after hepatectomy. Chemical shift imaging is a noninvasive tool that can identify metabolic changes coinciding with DNA synthesis and nuclear proliferation after hepatectomy. (31)P-NMR may be useful for determining safe timing of chemotherapy after liver resection.

Antitumor efficacy of regional oncolytic viral therapy for peritoneally disseminated cancer.

Oncolytic viral therapy is a promising new method of cancer treatment. Peritoneal dissemination of cancer is a common and fatal clinical condition seen in many malignancies, with few effective therapies available. G207, a multimutated replication-competent herpes simplex virus type-1, effectively treats disseminated peritoneal cancer. This study evaluates viral proliferation and subsequent tumoricidal effects in vitro and in vivo after regional viral delivery. In vitro studies demonstrate that G207 efficiently kills five human gastric cancer cell lines, and that permissiveness to viral replication is correlated with cytotoxicity. In a murine xenograft model of human gastric carcinomatosis, peritoneal delivery of G207 effectively kills tumor and prolongs survival. Data from quantitative PCR characterizes peritoneal clearance of virus after intraperitoneal injection, and identifies G207 replication within tumor cells in vivo, similar to in vitro proliferation. Further analysis of various organs confirms that G207 does not replicate within normal tissue after peritoneal delivery. Wild-type KOS viral replication was also demonstrated in vivo, with significant toxicity secondary to dissemination and encephalitis. In vivo viral proliferation of G207 is restricted to tumor cells, is correlated with in vitro assays, and is an important mechanism of anticancer efficacy.

Selective infection and cytolysis of human head and neck squamous cell carcinoma with sparing of normal mucosa by a cytotoxic herpes simplex virus type 1 (G207).

This study evaluates inhibition of human squamous cell carcinomas (SCCs) by a replication-competent multimutated herpes simplex virus type 1 (G207). Infectivity and cytotoxicity of the G207 virus were evaluated in vitro in seven human SCC cell lines. In vivo effects of the G207 virus on human tumor xenografts in an athymic rat model were then investigated by injecting established tumors with 1 x 10(7) virus particles and monitoring tumor growth. In addition, oral cavity tumors in immunocompetent hamster were infected with the G207 virus by selective intraarterial perfusion and the tumor response was monitored. In vitro studies demonstrated infection rates, measured 24 hr after exposure, exceeding 40% at an MOI of 2 in five of seven human SCC cell lines. Cytotoxic effects, as measured by percent cell death on day 5, exceeded 90% in five of seven SCC cell lines. In vivo inhibition of tumor growth in an athymic rat model was seen (p < 0.005) and in two of the cell lines a complete clinical response was seen in 12 of 14 tumors. In the hamster model, selective intraarterial perfusion with G207 virus showed selective infection of the tumor cells, with sparing of the adjacent normal mucosa, which leading to significant suppression of tumor growth (p < 0.005). The G207 virus displayed efficient and selective cytotoxicity and tumor growth inhibition against human SCC and may prove useful as a therapeutic agent for head and neck SCC.

Oncolytic viral therapy for human colorectal cancer and liver metastases using a multi-mutated herpes simplex virus type-1 (G207).

G207 is a multi-mutated, replication-competent type-1 herpes simplex virus designed to target, infect, and lyse neurological tumors. This study examines the feasibility of using G207 in the treatment of human colorectal cancer and defines the biological determinants of its antitumor efficacy. This virus was tested on five human colorectal cancer cell lines in vitro to determine efficacy of infection and tumor cell kill. These results were correlated to measures of tumor cell proliferation. In vivo testing was performed through direct injections of G207 into xenografts of human colorectal cancer tumors grown in flanks of athymic rats. To evaluate an alternate method of administration, hepatic portal vein infusion of G207 was performed in a syngeneic model of liver metastases in Buffalo rats. Among the five cell lines tested, infection rates ranged between 10% and 90%, which correlated directly with S-phase fraction (8.6%-36.6%) and was proportional to response to G207 therapy in vitro (1%-93%). Direct injection of G207 into nude rat flank tumors suppressed tumor growth significantly vs. control (0.58 +/- 0.60 cm(3) vs. 9.16 +/- 3.70 cm(3), P<0. 0001). In vivo tumor suppression correlated with in vitro effect. In the syngeneic liver tumor model, portal infusion resulted in significant reduction in number of liver nodules (13 +/- 10 nodules in G207-treated livers vs. 80 +/- 30 nodules in control livers, P<0.05). G207 infects and kills human colorectal cancer cells efficiently. In vitro cytotoxicity assay and tumor S-phase fraction can be used to predict response to treatment in vivo. This antineoplastic agent can be delivered effectively by both direct tumor injection and regional vascular infusion. G207 should be investigated further as therapy for colorectal cancer and liver metastases.