Vaccinia virus and peptide-receptor radiotherapy synergize to improve treatment of peritoneal carcinomatosis

Tumor-specific overexpression of receptors enables a variety of targeted cancer therapies, exemplified by peptide-receptor radiotherapy (PRRT) for somatostatin receptor (SSTR)-positive neuroendocrine tumors. While effective, PRRT is restricted to tumors with SSTR overexpression. To overcome this limitation, we propose using oncolytic vaccinia virus (vvDD)-mediated receptor gene transfer to permit molecular imaging and PRRT in tumors without endogenous SSTR overexpression, a strategy termed radiovirotherapy. We hypothesized that vvDD-SSTR combined with a radiolabeled somatostatin analog could be deployed as radiovirotherapy in a colorectal cancer peritoneal carcinomatosis model, producing tumor-specific radiopeptide accumulation. Following vvDD-SSTR and ¹⁷⁷Lu-DOTATOC treatment, viral replication and cytotoxicity, as well as biodistribution, tumor uptake, and survival, were evaluated. Radiovirotherapy did not alter virus replication or biodistribution, but synergistically improved vvDD-SSTR-induced cell killing in a receptor-dependent manner and significantly increased the tumor-specific accumulation and tumor-to-blood ratio of ¹⁷⁷Lu-DOTATOC, making tumors imageable by microSPECT/CT and causing no significant toxicity. ¹⁷⁷Lu-DOTATOC significantly improved survival over virus alone when combined with vvDD-SSTR but not control virus. We have therefore demonstrated that vvDD-SSTR can convert receptor-negative tumors into receptor-positive tumors and facilitate molecular imaging and PRRT using radiolabeled somatostatin analogs. Radiovirotherapy represents a promising treatment strategy with potential applications in a wide range of cancers.

Cutting both ways: the innate immune response to oncolytic virotherapy

Oncolytic viruses (OVs), above and beyond infecting and lysing malignant cells, interact with the immune system in complex ways that have important therapeutic significance. While investigation into these interactions is still in its early stages, important insights have been made over the past two decades that will help improve the clinical efficacy of OV-based management strategies in cancer care moving forward. The inherent immunosuppression that defines the tumor microenvironment can be modified by OV infection, and the subsequent recruitment and activation of innate immune cells, in particular, is central to this. Indeed, neutrophils, macrophages, natural killer cells, and dendritic cells, as well as other populations such as myeloid-derived suppressor cells, are key to the immune escape that allows tumors to survive, but their natural response to infection can be exploited by virotherapy. While stimulation of innate immune cells by OVs can initiate antitumor responses, related antiviral activity can limit virus spread and direct cytopathogenic effects. In this review, we highlight how each innate immune cell population influences this balance of antitumor and antiviral forces during virotherapy, some of the important molecular pathways that have been identified, and specific therapeutic targets that have emerged through this work. We discuss the importance of OV-based combination therapies in optimizing antiviral and antitumor innate immune responses stimulated by virotherapy toward tumor eradication, and how these processes vary depending on the tumor and OV in question. Rather than concentrating on a particular OV species in the review, we present the range of effects that have been documented across OV types to emphasize the context-specific nature of these interactions and how this is important in the design of future OV-based treatment approaches.

Deletion of immunomodulatory genes as a novel approach to oncolytic vaccinia virus development

Vaccinia virus (VV) has emerged as a promising platform for oncolytic virotherapy. Many clinical VV candidates, such as the double-deleted VV, vvDD, are engineered with deletions that enhance viral tumor selectivity based on cellular proliferation rates. An alternative approach is to exploit the dampened interferon-based innate immune responses of tumor cells by deleting one of the many VV immunomodulatory genes expressed to dismantle the antiviral response. We hypothesized that such a VV mutant would be attenuated in non-tumor cells but retain the ability to effectively propagate in and kill tumor cells, yielding a tumor-selective oncolytic VV with significant anti-tumor potency. In this study, we demonstrated that VVs with a deletion in one of several VV immunomodulatory genes (N1L, K1L, K3L, A46R, or A52R) have similar or improved in vitro replication, spread, and cytotoxicity in colon and ovarian cancer cells compared to vvDD. These deletion mutants are tumor selective, and the best performing candidates (ΔK1L, ΔA46R, and ΔA52R VV) are associated with significant improvement in survival, as well as immunomodulation, within the tumor environment. Overall, we show that exploiting the diminished antiviral responses in tumors serves as an effective strategy for generating tumor-selective and potent oncolytic VVs, with important implications in future oncolytic virus (OV) design.

Canadian guidelines on the management of colorectal peritoneal metastases

Modern management of colorectal cancer (crc) with peritoneal metastasis (pm) is based on a combination of cytoreductive surgery (crs), systemic chemotherapy, and hyperthermic intraperitoneal chemotherapy (hipec). Although the role of hipec has recently been questioned with respect to results from the prodige 7 trial, the role and benefit of a complete crs were confirmed, as observed with a 41-month gain in median survival in that study, and 15% of patients remaining disease-free at 5 years. Still, crc with pm is associated with a poor prognosis, and good patient selection is essential. Many questions about the optimal management approach for such patients remain, but all patients with pm from crc should be referred to, or discussed with, a pm surgical oncologist, because cure is possible. The objective of the present guideline is to offer a practical approach to the management of pm from crc and to reflect on the new practice standards set by recent publications on the topic.

Preclinical evaluation of a MAGE-A3 vaccination utilizing the oncolytic Maraba virus currently in first-in-human trials

Multiple immunotherapeutics have been approved for cancer patients, however advanced solid tumors are frequently refractory to treatment. We evaluated the safety and immunogenicity of a vaccination approach with multimodal oncolytic potential in non-human primates (NHP) (Macaca fascicularis). Primates received a replication-deficient adenoviral prime, boosted by the oncolytic Maraba MG1 rhabdovirus. Both vectors expressed the human MAGE-A3. No severe adverse events were observed. Boosting with MG1-MAGEA3 induced an expansion of hMAGE-A3-specific CD4⁺ and CD8⁺ T-cells with the latter peaking at remarkable levels and persisting for several months. T-cells reacting against epitopes fully conserved between simian and human MAGE-A3 were identified. Humoral immunity was demonstrated by the detection of circulating MAGE-A3 antibodies. These preclinical data establish the capacity for the Ad:MG1 vaccination to engage multiple effector immune cell populations without causing significant toxicity in outbred NHPs. Clinical investigations utilizing this program for the treatment of MAGE-A3-positive solid malignancies are underway (NCT02285816, NCT02879760).

Glove and instrument changing to prevent tumour seeding in cancer surgery: a survey of surgeons' beliefs and practices

Background

Some surgeons change gloves and instruments after the extirpative phase of cancer surgery with the intent of reducing the risk of local and wound recurrence. Although this practice is conceptually appealing, the evidence that gloves or instruments act as vectors of cancer-cell seeding in the clinical setting is weak. To determine the potential effect of further investigation of this question, we surveyed the practices and beliefs of a broad spectrum of surgeons who operate on cancer patients.

Methods

Using a modified Dillman approach, a survey was mailed to all 945 general surgeons listed in the College of Physicians and Surgeons of Ontario public registry. The survey consisted of multiple-choice and free-text response questions. Responses were tabulated and grouped into themes, including specific intraoperative events and surgeon training. Predictive variables were analyzed by chi-square test.

Results

Of 459 surveys returned (adjusted response rate: 46%), 351 met the inclusion criteria for retention. Of those respondents, 52% reported that they change gloves during cancer resections with the intent of decreasing the risk of tumour seeding, and 40%, that they change instruments for that purpose. The proportion of respondents indicating that they take measures to protect the wound was 73% for laparoscopic cancer resections and 31% for open resections. Training and years in practice predicted some of the foregoing behaviours. The most commonly cited basis for adopting specific strategies to prevent tumour seeding was "gut feeling," followed by clinical training. Most respondents believe that it is possible or probable that surgical gloves or instruments harbour malignant cells, but that a cancer recurrence proceeding from that situation is unlikely.

Conclusions

There is no consensus on how gloves and instruments should be handled in cancer operations. Further investigation is warranted.

Complement inhibition enables tumor delivery of LCMV glycoprotein pseudotyped viruses in the presence of antiviral antibodies

The systemic delivery of therapeutic viruses, such as oncolytic viruses or vaccines, is limited by the generation of neutralizing antibodies. While pseudotyping of rhabdoviruses with the lymphocytic choriomeningitis virus glycoprotein has previously allowed for multiple rounds of delivery in mice, this strategy has not translated to other animal models. For the first time, we provide experimental evidence that antibodies generated against the lymphocytic choriomeningitis virus glycoprotein mediate robust complement-dependent viral neutralization via activation of the classical pathway. We show that this phenotype can be capitalized upon to deliver maraba virus pseudotyped with the lymphocytic choriomeningitis virus glycoprotein in a Fischer rat model in the face of neutralizing antibody through the use of complement modulators. This finding changes the understanding of the humoral immune response to arenaviruses, and also describes methodology to deliver viral vectors to their therapeutic sites of action without the interference of neutralizing antibody.

Impact of Major Complications on Patients' Quality of Life After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

INTRODUCTION

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is an effective treatment for selected patients with peritoneal surface malignancies (PSM). Although it can have significant morbidity, perioperative mortality is low. Little is known about whether major complications after CRS/HIPEC have a lasting impact on patients' quality of life (QOL).

METHODS

We retrospectively reviewed data from a prospectively collected database on patients treated with CRS/HIPEC for PSM (2011-2014). Patients with CRS/HIPEC and 6-month QOL evaluation were included. Major perioperative complications (Clavien-Dindo grade 3/4) were the primary independent variable. QOL was evaluated using the validated EORTC QLQ-C30 score. The primary outcome was 6-month global health score. Secondary outcomes were individual functional and symptom domains.

RESULTS

Forty-two patients were analyzed. Median age was 57.5; 64 % were female. Origin of PSM was appendix (55 %), colorectal (38 %), mesothelioma (5 %), and small bowel (2 %). Fourteen patients (33 %) had major (grade 3/4) complications. Median length of stay was 16 days; patients experiencing major complications had significantly increased length of stay (35.5 vs. 13 days, p < 0.01). Major complications included intra-abdominal abscess (9.5 %), bleeding (9.5 %), symptomatic pleural effusion (7.1 %), anastomotic leaks (7.1 %), and renal failure (2.4 %). The average global health score at 6 months was 68.1. The worst-rated symptom scores at 6 months were diarrhea (39.8) and fatigue (35.4). There were no significant differences in 6-month QOL scores between patients with and without major complications, globally or in specific domains.

CONCLUSIONS

Although major complications are common after CRS/HIPEC, QOL at 6 months recovers and is similar to those without major complications.

Direct Lymph Node Vaccination of Lentivector/Prostate-Specific Antigen is Safe and Generates Tissue-Specific Responses in Rhesus Macaques

Anti-cancer immunotherapy is emerging from a nadir and demonstrating tangible benefits to patients. A variety of approaches are now employed. We are invoking antigen (Ag)-specific responses through direct injections of recombinant lentivectors (LVs) that encode sequences for tumor-associated antigens into multiple lymph nodes to optimize immune presentation/stimulation. Here we first demonstrate the effectiveness and antigen-specificity of this approach in mice challenged with prostate-specific antigen (PSA)-expressing tumor cells. Next we tested the safety and efficacy of this approach in two cohorts of rhesus macaques as a prelude to a clinical trial application. Our vector encodes the cDNA for rhesus macaque PSA and a rhesus macaque cell surface marker to facilitate vector titering and tracking. We utilized two independent injection schemas demarcated by the timing of LV administration. In both cohorts we observed marked tissue-specific responses as measured by clinical evaluations and magnetic resonance imaging of the prostate gland. Tissue-specific responses were sustained for up to six months-the end-point of the study. Control animals immunized against an irrelevant Ag were unaffected. We did not observe vector spread in test or control animals or perturbations of systemic immune parameters. This approach thus offers an "off-the-shelf" anti-cancer vaccine that could be made at large scale and injected into patients-even on an out-patient basis.

Peritoneal Carcinomatosis from Colon Cancer: A Systematic Review of the Data for Cytoreduction and Intraperitoneal Chemotherapy

A systematic review of the literature on the management of peritoneal carcinomatosis (PC) from colon cancer with cytoreductive surgery (CRS) and intraperitoneal chemotherapy (IPC) was undertaken using OVID Medline. Forty-six relevant studies were reviewed. Mean weighted overall morbidity following CRS and IPC was 49% (range 22-76%) and mortality was 3.6% (range 0-19%). Median overall survival ranged from 15 to 63 months, and 5-year overall survival ranged from 7 to 100%. This represents an improvement over historical treatment with systemic chemotherapy alone, even in the era of modern chemotherapeutic agents. Quality of life following surgery is initially decreased but improves with time and approaches baseline. Available data appear to support the treatment of PC from colon cancer with CRS and IPC. There is a large amount of variability among studies and few high-quality studies exist. Further studies are needed to standardize techniques.

Evidence for differential viral oncolytic efficacy in an in vitro model of epithelial ovarian cancer metastasis

Epithelial ovarian cancer is unique among most carcinomas in that metastasis occurs by direct dissemination of malignant cells traversing throughout the intraperitoneal fluid. Accordingly, we test new therapeutic strategies using an in vitro three-dimensional spheroid suspension culture model that mimics key steps of this metastatic process. In the present study, we sought to uncover the differential oncolytic efficacy among three different viruses—Myxoma virus, double-deleted vaccinia virus, and Maraba virus—using three ovarian cancer cell lines in our metastasis model system. Herein, we demonstrate that Maraba virus effectively infects, replicates, and kills epithelial ovarian cancer (EOC) cells in proliferating adherent cells and with slightly slower kinetics in tumor spheroids. Myxoma virus and vaccinia viruses infect and kill adherent cells to a much lesser extent than Maraba virus, and their oncolytic potential is almost completely attenuated in spheroids. Myxoma virus and vaccinia are able to infect and spread throughout spheroids, but are blocked in the final stages of the lytic cycle, and oncolytic-mediated cell killing is reactivated upon spheroid reattachment. Alternatively, Maraba virus has a remarkably reduced ability to initially enter spheroid cells, yet rapidly infects and spreads throughout spheroids generating significant cell killing effects. We show that low-density lipoprotein receptor expression in ovarian cancer spheroids is reduced and this controls efficient Maraba virus binding and entry into infected cells. Taken together, these results are the first to implicate the potential impact of differential viral oncolytic properties at key steps of ovarian cancer metastasis.

VEGF-Mediated Induction of PRD1-BF1/Blimp1 Expression Sensitizes Tumor Vasculature to Oncolytic Virus Infection

Oncolytic viruses designed to attack malignant cells can in addition infect and destroy tumor vascular endothelial cells. We show here that this expanded tropism of oncolytic vaccinia virus to the endothelial compartment is a consequence of VEGF-mediated suppression of the intrinsic antiviral response. VEGF/VEGFR2 signaling through Erk1/2 and Stat3 leads to upregulation, nuclear localization, and activation of the transcription repressor PRD1-BF1/Blimp1. PRD1-BF1 does not contribute to the mitogenic effects of VEGF, but directly represses genes involved in type I interferon (IFN)-mediated antiviral signaling. In vivo suppression of VEGF signaling diminishes PRD1-BF1/Blimp1 expression in tumor vasculature and inhibits intravenously administered oncolytic vaccinia delivery to and consequent spread within the tumor.

Guidelines on the use of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in patients with peritoneal surface malignancy arising from colorectal or appendiceal neoplasms

To meet the needs of patients, Canadian surgical and medical oncology leaders in the treatment of peritoneal surface malignancies (psms), together with patient representatives, formed the Canadian HIPEC Collaborative Group (chicg). The group is dedicated to standardizing and improving the treatment of psm in Canada so that access to treatment and, ultimately, the prognosis of Canadian patients with psm are improved. Patients with resectable psm arising from colorectal or appendiceal neoplasms should be reviewed by a multidisciplinary team including surgeons and medical oncologists with experience in treating patients with psm. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy should be offered to appropriately selected patients and performed at experienced centres. The aim of this publication is to present guidelines that we recommend be applied across the country for the treatment of psm.

Complement inhibition prevents oncolytic vaccinia virus neutralization in immune humans and cynomolgus macaques

Oncolytic viruses (OVs) have shown promising clinical activity when administered by direct intratumoral injection. However, natural barriers in the blood, including antibodies and complement, are likely to limit the ability to repeatedly administer OVs by the intravenous route. We demonstrate here that for a prototype of the clinical vaccinia virus based product Pexa-Vec, the neutralizing activity of antibodies elicited by smallpox vaccination, as well as the anamnestic response in hyperimmune virus treated cancer patients, is strictly dependent on the activation of complement. In immunized rats, complement depletion stabilized vaccinia virus in the blood and led to improved delivery to tumors. Complement depletion also enhanced tumor infection when virus was directly injected into tumors in immunized animals. The feasibility and safety of using a complement inhibitor, CP40, in combination with vaccinia virus was tested in cynomolgus macaques. CP40 pretreatment elicited an average 10-fold increase in infectious titer in the blood early after the infusion and prolonged the time during which infectious virus was detectable in the blood of animals with preexisting immunity. Capitalizing on the complement dependence of antivaccinia antibody with adjunct complement inhibitors may increase the infectious dose of oncolytic vaccinia virus delivered to tumors in virus in immune hosts.

Oncolytic vaccinia virus as an adjuvant treatment to cytoreductive surgery for malignant peritoneal mesothelioma

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is an aggressive cancer with a dismal prognosis. Oncolytic viruses are a promising new therapy for cancer because of their ability to kill tumor cells with minimal toxicity to normal tissues. This experimental study aimed to examine the potential of modified vaccinia virus (VV) to treat MPM when administered alone or as an adjuvant treatment to surgery.

METHODS

Two aggressive murine mesothelioma cell lines (AC29, AB12), were used. Cell viability and viral cytopathic effects were assessed using MTS and crystal violet assays. Immunocompetent mice were injected intraperitoneally with MPM cells and treated with intraperitoneal VV. Tumor-bearing mice also underwent cytoreductive surgery (CRS) followed by VV (or control) therapy.

RESULTS

The cytotoxic effects of VV on MPM cell lines was significantly increased compared with the control non-cancer cell line. In both orthotopic models, VV induced tumor regression, prolonging median and long-term survival. VV treatment after incomplete CRS was not superior to VV alone; however, when mice with microscopic disease were treated with VV, further prolongation of median and long-term survivals was observed.

CONCLUSIONS

VV selectively kills MPM cells in vitro and leads to improved survival and cures in immunocompetent murine models. Higher efficacy of the virus in the microscopic disease context suggests the use of the virus as an adjuvant treatment to complete surgical resection. These promising results justify further studies of VV in humans as a novel treatment for MPM.

Physicians' awareness of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for colorectal cancer carcinomatosis

BACKGROUND

Recent trials have shown that cytoreductive surgery and heated intraperitoneal chemotherapy (S+HIPEC) for colorectal cancer carcinomatosis (CRC-C) leads to 5-year, disease-free survival rates of more than 30%. Since these data represent a substantial change in the management of CRC-C, the objectives of this study were to determine physicians' awareness of S+HIPEC for CRC-C and physician characteristics predictive of awareness of S+HIPEC for CRC-C.

METHODS

This study was a mailed, cross-sectional survey of general surgeons and medical oncologists in Ontario.

RESULTS

The response rate was 44.0% (214 of 487). Most respondents were men and younger than 50 years. There was an even split between those at academic and community hospitals. Overall, 46% of respondents were aware of S+HIPEC for CRC-C, and multivariate analysis showed that there were no physician characteristics predictive of awareness of S+HIPEC for CRC-C.

CONCLUSION

Physician awareness of S+HIPEC for CRC-C is low. Therefore, strategies to improve patient and physician knowledge about S+HIPEC for CRC-C are important to ensure appropriate treatment for patients.

Tumor vascularization is critical for oncolytic vaccinia virus treatment of peritoneal carcinomatosis

Peritoneal carcinomatosis (PC) represents a significant clinical challenge for which there are few treatment options. Oncolytic viruses are ideal candidates for PC treatment because of their high tumor specificity, excellent safety profile and suitability for peritoneal delivery. Here, we described the use of vvDD-SR-RFP, a recombinant vaccinia virus, in xenograft and syngeneic models of colorectal PC. Colorectal cancer cell lines were highly susceptible to vvDD-SR-RFP replication and cytotoxicity. Intraperitoneal delivery of vvDD-SR-RFP on Day 12 to mice with colorectal carcinomatosis significantly improved survival whereas survival was not improved following virus treatment on Day 8, when tumors were smaller. Immunohistochemistry revealed early tumors had a poorly distributed network of blood vessels and lower proliferation index compared to later tumors. Virus infection was also restricted to tumor rims following Day 8 treatment, whereas it was disseminated in tumors treated on Day 12. Additionally, direct infection of tumor endothelium was observed and virus infection correlated with a loss of endothelial staining and induction of cell death. Our results demonstrate that tumor vasculature has a critical role in virus delivery and tumor response. This will have significant implications in the clinical setting, both in understanding timing of therapies and in designing combination treatment strategies.

Mounting a strategic offense: fighting tumor vasculature with oncolytic viruses

Blood supply within a tumor drives progression and ultimately allows for metastasis. Many anticancer therapies target tumor vasculature, but their individual effectiveness is limited because they induce indirect cell death. Agents that disrupt nascent and/or established tumor vasculature while simultaneously killing cancer cells would certainly have a greater impact. Oncolytic virotherapy utilizes attenuated viruses that replicate specifically within a tumor. They induce cytotoxicity through a combination of direct cell lysis, antitumor immune stimulation, and recently identified antitumor vascular effects. This review summarizes the novel preclinical and clinical evidence regarding the antitumor vascular effects of oncolytic viruses, which include infection and lysis of tumor endothelial cells, natural or genetically engineered antiangiogenic properties, and combination therapy with clinically approved antivascular agents.

Autologous transplantation of lentivector/acid ceramidase-transduced hematopoietic cells in nonhuman primates

Farber disease is a rare lysosomal storage disorder (LSD) that manifests due to acid ceramidase (AC) deficiencies and ceramide accumulation. We present a preclinical gene therapy study for Farber disease employing a lentiviral vector (LV-huAC/huCD25) in three enzymatically normal nonhuman primates. Autologous, mobilized peripheral blood (PB) cells were transduced and infused into fully myelo-ablated recipients with tracking for at least 1 year. Outcomes were assessed by measuring the AC specific activity, ceramide levels, vector persistence/integration, and safety parameters. We observed no hematological, biochemical, radiological, or pathological abnormalities. Hematological recovery occurred by approximately 3 weeks. Vector persistence was observed in PB and bone marrow (BM) cells by qualitative and quantitative PCR. We did not observe any clonal proliferation of PB and BM cells. Importantly, AC-specific activity was detected above normal levels in PB and BM cells analyzed post-transplantation and in spleens and livers at the endpoint of the study. Decreases of ceramide in PB cells as well as in spleen and liver tissues were seen. We expect that this study will provide a roadmap for implementation of clinical gene therapy protocols targeting hematopoietic cells for Farber disease and other LSDs.

Synergistic interaction between oncolytic viruses augments tumor killing

A major barrier to all oncolytic viruses (OVs) in clinical development is cellular innate immunity, which is variably active in a spectrum of human malignancies. To overcome the heterogeneity of tumor response, we combined complementary OVs that attack cancers in distinct ways to improve therapeutic outcome. Two genetically distinct viruses, vesicular stomatitis virus (VSV) and vaccinia virus (VV), were used to eliminate the risk of recombination. The combination was tested in a variety of tumor types in vitro, in immunodeficient and immunocompetent mouse tumor models, and ex vivo, in a panel of primary human cancer samples. We found that VV synergistically enhanced VSV antitumor activity, dependent in large part on the activity of the VV B18R gene product. A recombinant version of VSV expressing the fusion-associated small-transmembrane (p14FAST) protein also further enhanced the ability of VV to spread through an infected monolayer, resulting in a "ping pong" oncolytic effect wherein each virus enhanced the ability of the other to replicate and/or spread in tumor cells. Our strategy is the first example where OVs are rationally combined to utilize attributes of different OVs to overcome the heterogeneity of malignancies and demonstrates the feasibility of combining complementary OVs to improve therapeutic outcome.

Intelligent design: combination therapy with oncolytic viruses

Metastatic cancer remains an incurable disease in the majority of cases and thus novel treatment strategies such as oncolytic virotherapy are rapidly advancing toward clinical use. In order to be successful, it is likely that some type of combination therapy will be necessary to have a meaningful impact on this disease. Although it may be tempting to simply combine an oncolytic virus with the existing standard radiation or chemotherapeutics, the long-term goal of such treatments must be to have a rational, potentially synergistic combination strategy that can be safely and easily used in the clinical setting. The combination of oncolytic virotherapy with existing radiotherapy and chemotherapy modalities is reviewed along with novel biologic therapies including immunotherapies, in order to help investigators make intelligent decisions during the clinical development of these products.

Efficacy of systemically administered oncolytic vaccinia virotherapy for malignant gliomas is enhanced by combination therapy with rapamycin or cyclophosphamide

PURPOSE

The oncolytic effects of a systemically delivered, replicating, double-deleted vaccinia virus has been previously shown for the treatment of many cancers, including colon, ovarian, and others. The purpose of this study was to investigate the oncolytic potential of double-deleted vaccinia virus alone or in combination with rapamycin or cyclophosphamide to treat malignant gliomas in vitro and in vivo.

EXPERIMENTAL DESIGN

Rat (RG2, F98, C6) and human (A172, U87MG, U118) glioma cell lines were cultured in vitro and treated with live or UV-inactivated vaccinia virus. Viral gene [enhanced green fluorescent protein (EGFP)] expression by fluorescence-activated cell sorting, relative cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and assays for cytopathic effects were examined. S.c. murine tumor xenografts (U87MG, U118, C6) and i.c. (RG2, F98) tumor models in immunocompetent rats were treated with systemic administration of EGFP-expressing vaccinia virus (vvDD-EGFP), alone or in combination with rapamycin or cyclophosphamide, or controls. Tumor size, viral biodistribution, and animal survival were assessed. Lastly, the oncolytic effects of vvDD-EGFP on human malignant glioma explants were evaluated.

RESULTS

vvDD-EGFP was able to infect and kill glioma cells in vitro. A single systemic dose of vvDD-EGFP significantly inhibited the growth of xenografts in athymic mice. Systemic delivery of vvDD-EGFP alone was able to target solitary and multifocal i.c. tumors and prolong survival of immunocompetent rats, whereas combination therapy with rapamycin or cyclophosphamide enhanced viral replication and further prolonged survival. Finally, vvDD-EGFP was able to infect and kill ex vivo primary human malignant gliomas.

CONCLUSIONS

These results suggest that vvDD-EGFP is a promising novel agent for human malignant glioma therapy, and in combination with immunosuppressive agents, may lead to prolonged survival from this disease.

Potent induction of B- and T-cell immunity against human carcinoembryonic antigen-expressing tumors in human carcinoembryonic antigen transgenic mice mediated by direct lentivector injection

The applicability of immunotherapy would be dramatically broadened to a greater number of recipients if direct "off-the-shelf" products could be engineered to engender functionally potent immune responses against true "self"-tumor antigens. This would obviate the need for ex vivo culture of dendritic cells or T cells on a patient-by-patient basis, for example. The carcinoembryonic antigen (CEA) is a glycoprotein expressed in normal gut epithelium that is up-regulated in the majority of colon cancers, non-small cell lung cancers, and half of all breast cancers. Such properties make CEA an excellent and important target for cancer immunotherapy. In this study, we show stabilization of 14-day established s.c. mGC4CEA tumors in human CEA (huCEA) transgenic mice following two direct low-dose injections of 0.15x10(6) transducing units of a lentiviral vector (LV) that directs expression of huCEA (LV-huCEA). This stabilization result was reproducible and detailed analyses including antibody assays, multiplex cytokine analyses on unstimulated splenocytes, lymph node cell characterizations, tetramer staining, and immunofluorescence staining of tumor sections showed that this outcome correlated with both a cellular and humoral immune response. Similar tumor outcomes were not seen when mice were vaccinated with a control LV that engineered expression of enGFP only. The long-term potency of this vaccination strategy was also studied and revealed the requirement for maintenance of tumor antigen-specific immunity for efficient tumor control. These data support the use of direct injections of low doses of LV-huCEA for enhancement of tumor immunotherapy directed against CEA.

Oncolytic virotherapy for multiple myeloma

BACKGROUND

Current therapies for multiple myeloma (MM) are not curative, thus novel targeted therapeutics are being developed. One such targeted therapy is oncolytic virotherapy, wherein viruses specifically infect and kill the malignant plasma cells, leaving normal cells intact.

OBJECTIVE

This review provides an overview of the mechanisms and results of the oncolytic viruses being used to date and discusses the recent advances in the field of virotherapy for MM.

METHODS

All papers using viruses to treat MM were identified and screened. Only papers describing replicating, oncolytic viruses were reviewed.

RESULTS/CONCLUSIONS

Several viruses are currently being developed preclinically and clinically to treat MM, including measles virus, vesicular stomatitis virus, coxsackievirus A21 and vaccinia virus. Other viruses are being used preclinically to purge myeloma cells from autologous bone marrow transplants. Efforts to improve myeloma-specific targeting, avoid the antiviral immune response and evaluate combination therapies for MM are ongoing.

A roadmap to safe, efficient, and stable lentivirus-mediated gene therapy with hematopoietic cell transplantation

Hematopoietic stem cells comprise a prominent target for gene therapy aimed at treating various genetic and acquired disorders. A number of limitations associated with hematopoietic cell transplantation can be circumvented by the use of cells stably modified by retroviral gene transfer. Oncoretroviral and lentiviral vectors offer means for generating efficient and stable transgene expression. This review summarizes the state of the field today in terms of vector development and clinical experimentation. In particular, concerns with the safety of retroviral vectors intended for clinical gene transfer, applicability of preclinical data in directing clinical trial design, and recent research aimed at resolving some of these issues are addressed. Finally, this review underlines the specific advantages offered by lentiviral gene-transfer vectors for gene therapy in stem cells.

Targeted inflammation during oncolytic virus therapy severely compromises tumor blood flow

Oncolytic viruses (OVs) are selected or designed to eliminate malignancies by direct infection and lysis of cancer cells. In contrast to this concept of direct tumor lysis by viral infection, we observed that a significant portion of the in vivo tumor killing activity of two OVs, vesicular stomatitis virus (VSV) and vaccinia virus is caused by indirect killing of uninfected tumor cells. Shortly after administering the oncolytic virus we observed limited virus infection, coincident with a loss of blood flow to the interior of the tumor that correlated with induction of apoptosis in tumor cells. Transcript profiling of tumors showed that virus infection resulted in a dramatic transcriptional activation of pro-inflammatory genes including the neutrophil chemoattractants CXCL1 and CXCL5. Immunohistochemical examination of infected tumors revealed infiltration by neutrophils correlating with chemokine induction. Depletion of neutrophils in animals prior to VSV administration eliminated uninfected tumor cell apoptosis and permitted more extensive replication and spreading of the virus throughout the tumor. Taken all together, these results indicate that targeted recruitment of neutrophils to infected tumor beds enhances the killing of malignant cells. We propose that activation of inflammatory cells can be used for enhancing the effectiveness of oncolytic virus therapeutics, and that this approach should influence the planning of therapeutic doses.

Intravenous and isolated limb perfusion delivery of wild type and a tumor-selective replicating mutant vaccinia virus in nonhuman primates

In this study we examine the safety, feasibility, and biodistribution of a tumor-selective mutant vaccinia (vvDD) and wild-type WR (vF13) vaccinia after delivery via intradermal or intravenous infection or isolated limb perfusion (ILP) in rhesus macaques. By intradermal inoculation, 10(6) PFU of vvDD caused a minimal skin reaction whereas vF13 caused marked erythema and necrosis with a peak indurated area of 108 cm2. By intravenous delivery, vvDD caused no clinical symptoms of viremia and no viral recovery from tissues, serum, saliva, urine, or feces. In contrast, vF13 caused symptoms of lethargy, anorexia, fever, and signs of viremia. Delivery of vF13 via ILP resulted in numerous cutaneous pox lesions localized solely to the perfused limb with high viral recovery in the perfused skin and muscle. ILP with vvDD resulted in no visible pox lesions and no clinical signs or symptoms of viremia. No long-term toxicity was identified after ILP with 10(9) PFU of vvDD, and no virus was recovered from any tissue, serum, saliva, urine, or fecal sample. These results suggest that vvDD appears to be safe in primates, and thus vvDD should be further investigated for clinical trial in human cancer patients.

Oncolytic vaccinia virus expressing the human somatostatin receptor SSTR2: molecular imaging after systemic delivery using 111In-pentetreotide

Oncolytic vaccinia viruses (VV) have demonstrated tumor specificity, high levels of transgene expression, and anti-tumor effects. The ability to visualize vector biodistribution noninvasively will be necessary as gene therapy vectors come to clinical trials, and the creation of a VV that can both treat tumors and permit noninvasive imaging after systemic delivery is therefore an exciting concept. To facilitate imaging, a VV expressing the human somatostatin receptor type 2 (SSTR2) was created. Cells infected with the SSTR2-expressing VV or controls were incubated with the somatostatin analog 111In-pentetreotide with or without an excess of nonradiolabeled pentetreotide. The SSTR2-infected cells bound 111In-pentetreotide sixfold more efficiently than control virus-infected cells and this binding was specifically blocked by nonradiolabeled pentetreotide. Nude mice bearing subcutaneous murine colon CA xenografts were injected intraperitoneally with the SSTR2-expressing VV or control VV. After 6 days, mice were injected with 111In-pentetreotide and imaged. Mice were sacrificed and organs collected and counted in a gamma counter. The uptake of radioactivity in tumors and normal tissues (percentage injected dose per gram) and tumor-to-normal tissue ratios were determined. Tumors infected with the SSTR2-expressing VV accumulated significantly higher concentrations of radioactivity compared to tumors in animals receiving the control virus. SSTR2-infected tumors were visible on imaging 6 days after VV injection and could be visualized for up to 3 weeks post-viral injection using repeat injections of 111In-pentetreotide. This reporter gene imaging strategy could be a very effective method to visualize vector distribution, expression, and persistence over time and enhances the potential of VV as a novel anti-cancer therapeutic.

Soluble Interleukin-13Rα2 Decoy Receptor Inhibits Hodgkin’s Lymphoma Growth in Vitro and in Vivo

Recent studies have demonstrated that the malignant Reed-Sternberg cells of Hodgkin's lymphoma (HL) secrete and are responsive to interleukin (IL)-13. We hypothesized that overexpression of a soluble IL-13 decoy receptor (sIL-13Ralpha2) via adenoviral-mediated gene transfer would inhibit IL-13-induced Reed-Sternberg cell proliferation. Western blot and ELISA analysis verified expression of sIL-13Ralpha2 in cell lysates and supernatants of AdsIL-13Ralpha2-transduced COS-7 cells. Treatment of two IL-13-responsive HL-derived cell lines, HDLM-2 and L-1236, with AdsIL-13Ralpha2-conditioned medium, resulted in the inhibition of cell proliferation, and down-regulated the phosphorylation of signal transducer and activator of transcription 6 (STAT6), an important mediator of IL-13 signaling. i.v. delivery of AdsIL-13Ralpha2 in NOD/SCID mice with s.c. implanted HDLM-2 cells delayed tumor onset and growth while enhancing survival compared with control mice. Intratumoral administration of AdsIL-13Ralpha2 led to the regression or stabilization of established tumors and was associated with diminished STAT6 phosphorylation. Our data demonstrate that AdsIL-13Ralpha2 can suppress HL growth in vitro and in vivo.

Persistent primary hyperparathyroidism caused by adenomas identified in pharyngeal or adjacent structures

Abnormalities in the normal migration of the parathyroid glands during embryological development of the head and neck may result in considerable variability in the location of parathyroid tissue. Ectopic parathyroid adenomas present diagnostic and technical challenges and are frequently the cause of persistent primary hyperparathyroidism (HPT) after unsuccessful initial parathyroid surgery. We report a series of eight patients with persistent primary HPT who had adenomas in rare and unusual locations associated with various pharyngeal structures. Four were located within the epineurium of the vagus nerve at or above the level of the carotid bifurcation, and four were located within the paranasopharyngeal space or oropharynx. Noninvasive and invasive preoperative imaging studies were crucial in localizing the neoplasms in these patients and permitted the use of a direct surgical approach, resulting in cure in all patients and a low complication rate. The location of parathyroid glands in high pharyngeal and cervical structures is a consequence of anomalous or arrested descent through developing pharyngeal structures and illustrates the remarkable spectrum of ectopic parathyroid adenomas that occur secondary to this phenomenon.

Development of a melanoma-specific adenovirus

Concerns regarding the hepatotoxicity of adenovirus for cancer gene therapy have led to attempts to engineer viruses for tissue-specific gene expression and tissue-specific replication. The Tyrex2 (a tandem murine melanocyte-specific enhancer) system was used to express luciferase, purine nucleoside phosphorylase (PNP), and the essential adenoviral gene E1A. In nonmelanoma cell lines, the CMV promoter/enhancer (CMV p/e) was 969 times stronger than the Tyrex2 construct, whereas in melanoma cells it was only 2.6 times stronger. An adenovirus with Tyrex2 regulating PNP (Ad2Tyr2-PNP) was tested for cytotoxicity. In melanoma cells, treatment with Ad2Tyr2-PNP plus the prodrug 6-methylpurine deoxyriboside (6-MPDR) resulted in 90% cytotoxicity by day 4. In non-melanoma cell lines, only the CMV p/e resulted in significant cytotoxicity. We compared the intrinsic E1A promoter/enhancer (E1A p/e) system with the melanoma-specific constructs and found that the Tyrex2 system achieved higher levels of luciferase than the E1A p/e in all melanoma lines tested. In non-melanoma cell lines, the E1A p/e is 12.4 times stronger than the Tyrex2 construct. Tyrex2 was then used to regulate adenoviral E1A expression to construct a melanoma-specific replicating adenovirus. We were unable to achieve selective replication. As E1A is a known transactivator of the adenovirus major late promoter (MLP), we studied the ability of the MLP to express a transgene in the context of tissue-selective E1A expression. We were able to demonstrate high levels of luciferase activity with this construct; however, selectivity was lost. Melanoma-specific adenovirus expression was achieved with the Tyrex2 construct, and this led to melanoma-specific cytotoxicity by the potent PNP suicide gene. Selective melanoma-specific replication was not successful. The MLP may be a useful promoter in the context of a tissue-specific replicating adenovirus.

Rapid measurement of insulin using the Abbott IMx: application to the management of insulinoma

BACKGROUND

Patients with multiple endocrine neoplasia (type 1) often present with multiple pancreatic endocrine tumours, such as insulinomas. A major difficulty in the surgical treatment of such patients is identifying which tumours are functionally active and therefore need to be resected for a cure. The objective of this study was to develop a rapid insulin assay that could be used intraoperatively for identifying insulinomas from pancreatic aspirates.

METHODS

By reducing the incubation time and by increasing the sample volume, a rapid insulin assay was developed on the IMx analyser. This was used to measure insulin from tissue aspirates collected from suspected insulinomas under ultrasound guidance.

RESULTS

The rapid insulin assay (y) could be performed in 14 min and showed a good correlation with the standard IMx (x) insulin assay (y = 0.808x + 0.04; r(2) = 0.986). Using the rapid insulin assay on pancreatic tissue aspirates, insulinomas could be readily distinguished from normal pancreatic tissue or from non-functional adenomas based on a marked increase in insulin content.

CONCLUSION

In summary, a new rapid assay for insulin is described that compares favourably to the standard IMx insulin assay and can potentially be used intraoperatively on pancreatic aspirates for identifying functionally active insulinomas.

Systemic cancer therapy with a tumor-selective vaccinia virus mutant lacking thymidine kinase and vaccinia growth factor genes

We have demonstrated previously the oncolytic effects of a systemically delivered, replicating vaccinia virus. To enhance the tumor specificity of this vector, we have developed a combined thymidine kinase-deleted (TK-) and vaccinia growth factor-deleted (VGF-) vaccinia virus and investigated its properties in vitro and in vivo. The gene for enhanced green fluorescent protein (EGFP) was inserted into the TK locus of a VGF- vaccinia virus by homologous recombination creating a double-deleted mutant vaccinia virus (vvDD-GFP). Infection of resting and dividing NIH3T3 cells with vvDD-GFP yielded reduced viral recovery compared with wild-type (WT), TK-, or VGF- viruses from resting cultures but equivalent virus recovery from dividing cultures. Eight days after nude mice were injected i.p. with 10(7) plaque-forming units (pfu) of WT, TK-, VGF-, or vvDD-GFP vaccinia virus, tissues and tumor were harvested for viral titer determination. No virus was recovered from the brains of mice injected with vvDD-GFP compared with the other viruses, which ranged from 130 to 28,000 pfu/mg protein; however, equivalent amounts were recovered from tumor. There was no toxicity from vvDD-GFP because nude mice receiving 10(8) pfu of IP vvDD-GFP lived >100 days, whereas mice receiving WT, VGF-, or TK- virus had median survivals of only 6, 17, and 29 days, respectively. Similar results were seen when 10(9) pfu of vvDD-GFP were given. Nude mice bearing s.c. murine colon adenocarcinoma (MC38) had significant tumor regression after treatment with 10(9) pfu of systemic (i.p.) vvDD-GFP compared with control (mean tumor size, 180.71 +/- 35.26 mm(3) versus 2796.79 +/- 573.20 mm(3) 12 days after injection of virus). Our data demonstrate that a TK- and VGF- mutant vaccinia virus is significantly attenuated in resting cells in vitro and demonstrates tumor-specific replication in vivo. It is a promising vector for use in tumor-directed gene therapy, given its enhanced safety profile, tumor selectivity, and the oncolytic effects after systemic delivery.

Reoperation for hyperparathyroidism in multiple endocrine neoplasia type 1

BACKGROUND

Patients with multiple endocrine neoplasia type 1 and hyperparathyroidism often undergo multiple operations because of inadequate initial surgery, presence of supernumerary and ectopic glands, regrowth of remnant glands, or autograft hyperfunction. Management of this patient population is complex.

METHODS

From January 1975 to December 2000 we performed 94 reoperative parathyroidectomies consisting of 79 neck reexplorations, 12 autograft removals, and 3 median sternotomies in 75 patients. Data were gathered by retrospective chart review and follow-up telephone interviews.

RESULTS

Excluding autograft excision, reoperative surgery was successful (normocalcemia longer than 6 months) in 91%; autograft removal was successful in only 58%. With a median follow-up of 59 months, 64% of patients are currently free from hypercalcemia, and this outcome was not influenced by the total number of glands resected. The median time to recurrent hypercalcemia was 125 months. Thirty patients received an autograft after reoperation. The complication rate for all reoperations was 12%, including permanent recurrent laryngeal nerve injury in 2 patients (2.1%).

CONCLUSIONS

Reoperative parathyroidectomy in patients with multiple endocrine neoplasia type 1 was safe and successful in the majority of patients; however, recurrent hyperparathyroidism is likely to develop in most individuals beyond 10 years of follow-up. The total number of glands accounted for after reoperation is not associated with successful outcome.

Yaba-like disease virus: an alternative replicating poxvirus vector for cancer gene therapy

Vaccinia virus is being investigated as a replicating vector for tumor-directed gene therapy. However, the majority of cancer patients have preformed immunologic reactivity against vaccinia virus, as a result of smallpox vaccination, which may limit its use as a vector. The Yaba-like disease (YLD) virus was investigated here as an alternative, replicating poxvirus for cancer gene therapy. We have demonstrated that the YLD virus does not cross-react with vaccinia virus antibodies, and it replicates efficiently in human tumor cells. YLD virus can be expanded and purified to high titer in CV-1 cells under conditions utilized for vaccinia virus. The YLD virus RNA polymerase was able to express genes regulated by a synthetic promoter designed for use in orthopoxviruses. We sequenced the YLD virus TK gene and created a shuttle plasmid, which allowed the recombination of the green fluorescent protein (GFP) gene into the YLD virus. In a murine model of ovarian cancer, up to 38% of cells in the tumor expressed the GFP transgene 12 days after intraperitoneal virus delivery. YLD virus has favorable characteristics as a vector for cancer gene therapy, and this potential should be explored further.

Complex interactions between the replicating oncolytic effect and the enzyme/prodrug effect of vaccinia-mediated tumor regression

Replicating viruses for cancer gene therapy have beneficial antitumor effects, however, in the setting of an enzyme/prodrug system, the interactions between these viruses and the activated agents are complex. A replicating vaccinia virus expressing the cytosine deaminase gene (VVCD), which converts the prodrug 5-FC into 5-FU, was characterized in vitro and in vivo for its antitumor effects and pathogenicity. Replicating VVCD (+/-5-FC) at various MOIs was used to infect MC38 murine colon adenocarcinoma cells. At high MOIs (>0.1) virus alone was able to kill the majority (65-90%) of cells by day 5 with no additional benefit from prodrug. At low MOIs only the effect of prodrug is seen. Cell lysates demonstrated 300-fold reduced viral recovery from cells treated with both VVCD and 5-FC compared with controls treated with virus alone. Nude mice bearing subcutaneous MC38 tumors were injected with VVCD (or control) and treated with 5FC or control. Mice injected with VVCD (with or without 5FC treatment) had smaller tumors than the controls, suggesting that replicating vaccinia alone is cytotoxic to tumors in vivo. The addition of 5-FC improved the antitumor response when a low dose of virus was injected into tumors. Also, compared with mice that received virus alone, those that received VVCD and 5FC had significantly prolonged survival from virus-mediated death. In conclusion, the addition of an enzyme/prodrug system to a replicating virus can improve the antitumor response and decrease viral pathogenicity. Gene Therapy (2000) 7, 1217-1223.

Ferumoxide-enhanced MRI in patients with colorectal cancer and rising CEA: surgical correlation in early recurrence

The purpose of this study was to evaluate the value of Ferumoxide-enhanced magnetic resonance (MR) imaging in the detection of hepatic metastases in high-risk patients treated for colorectal cancer that have rising CEA. We used 19 patients treated previously for colorectal cancer with rising CEA levels underwent an unenhanced T(1)-weighted (T1W), T(2)-weighted (T2W), STIR, and Ferumoxide-enhanced hepatic MRI. Following these studies, a laparotomy was performed and the liver was evaluated by palpation and intraoperative ultrasound. Two observers who were blinded to surgical results evaluated each MR sequence separately. The number of lesions considered highly suspicious for metastatic lesions were determined for each sequence and were compared to the results of surgery. The McNemar test was used to compare the outcomes of the different sequences. MR Imaging was unable to detect small (<5 mm) metastases discovered at surgery. The best non-contrast sequences for detecting metastases were the STIR with 42% sensitivity, 83% specificity and an overall accuracy of 56% and the T1W sequence (sensitivity 38%, specificity 100%, accuracy 57%), which were not significantly different (p 0.4). The noncontrast T2W sequence had a sensitivity of 29% and a specificity of 77% with an overall accuracy of 46%. When all pre contrast scans were grouped together the common sensitivity was 42%, specificity was 77% and accuracy was 54%. The post-ferumoxide T(2)W scans had a sensitivity of 42%, specificity of 85%, and accuracy of 57%, but did not detect any additional lesions. There was no statistical difference between the pre- and post-contrast studies with regard to identifying patients with metastatic disease (p 0.1). In conclusion, we found small hepatic metastases in patients with early signs of recurrent colorectal cancer are difficult to detect on MRI. Ferumoxide-enhanced MRI was unable to detect additional hepatic metastases and performed no better than unenhanced MRI in detecting small hepatic metastasis.

ras mutation and expression of the ras-regulated genes osteopontin and cathepsin L in human esophageal cancer

As part of our ongoing studies to characterize molecular alterations in a well-defined series of surgically resected esophageal cancers, we examined the expression of 2 ras-regulated genes, whose products (osteopontin and cathepsin L) previously were shown to be associated with tumor invasion and metastasis. RNA was extracted from primary esophageal tumors (adenocarcinomas, 19; squamous-cell carcinomas, 6) and matched histologically normal esophageal mucosa from the distant resection margin. Northern analysis was used to quantitate RNA, relative to an 18S rRNA control, and immunohistochemistry to assess the tissue distribution of osteopontin. In addition, H-, K- and N-ras mutations were studied in the same tissues using PCR and hybridization with allele (mutant)-specific oligonucleotide probes. We demonstrated a K-ras mutation (codon 12, GTT) in one esophageal adenocarcinoma. The ras-regulated gene osteopontin was over-expressed in 100% of squamous-cell carcinomas and in 58% of adenocarcinomas relative to matched normal esophageal mucosa. Patterns of immunoreactivity for osteopontin protein also varied between squamous-cell carcinomas (tumor cell staining) and adenocarcinomas (predominantly tumor-infiltrating macrophages). Expression of cathepsin L also varied with esophageal tumor histology, with over-expression in 58% of primary esophageal adenocarcinomas and 33% of squamous-cell cancers.

ras mutation and expression of the ras-regulated genes osteopontin and cathepsin L in human esophageal cancer

As part of our ongoing studies to characterize molecular alterations in a well-defined series of surgically resected esophageal cancers, we examined the expression of 2 ras-regulated genes, whose products (osteopontin and cathepsin L) previously were shown to be associated with tumor invasion and metastasis. RNA was extracted from primary esophageal tumors (adenocarcinomas, 19; squamous-cell carcinomas, 6) and matched histologically normal esophageal mucosa from the distant resection margin. Northern analysis was used to quantitate RNA, relative to an 18S rRNA control, and immunohistochemistry to assess the tissue distribution of osteopontin. In addition, H-, K- and N-ras mutations were studied in the same tissues using PCR and hybridization with allele (mutant)-specific oligonucleotide probes. We demonstrated a K-ras mutation (codon 12, GTT) in one esophageal adenocarcinoma. The ras-regulated gene osteopontin was over-expressed in 100% of squamous-cell carcinomas and in 58% of adenocarcinomas relative to matched normal esophageal mucosa. Patterns of immunoreactivity for osteopontin protein also varied between squamous-cell carcinomas (tumor cell staining) and adenocarcinomas (predominantly tumor-infiltrating macrophages). Expression of cathepsin L also varied with esophageal tumor histology, with over-expression in 58% of primary esophageal adenocarcinomas and 33% of squamous-cell cancers.

Genetic modulation in the pathogenesis and treatment of cancer

Recent advances in molecular biology have improved our understanding of the pathogenesis of cancer. Molecular genetic alterations have been characterized in lung and esophageal tumors, and have potential clinical application in tumor diagnosis, staging, prevention, and therapy.

Predictors of survival following surgical resection of thymoma

The aim of this study was to determine the predictors of long-term survival following surgical resection of thymoma. Forty-one patients with a histologically proven diagnosis of thymoma were evaluated and treated over a 30-year period (1961 to 1991) at our institution. Seven patients (Masaoka stage III or IV) were unresectable and were treated by radiotherapy and/or chemotherapy, with an overall 5 year survival of 50%. Thirty-four patients underwent primary surgical excision of the thymoma, most often through a median sternotomy, with 5- and 10-year survivals of 90%. Complete excision of the thymoma was achieved in 31 patients with a median survival of 54 months vs. 17 months if incomplete. Independent prognostic factors influencing survival were stage, histology, and patients judged to have a benign thymoma at surgery. Although the thymoma was associated with myasthenia gravis (8 patients) and second primary cancers (8 patients), neither factor was associated with overall survival. We conclude that the most significant predictors of long-term survival of thymoma include complete excision, Masaoka stage I disease, and lymphocytic histology. Multivariate analysis suggested that postoperative chemoradiotherapy may impact on survival.