Tropism For Tumor Cells Research Articles

Phase I Trial of Systemic Administration of Vesicular Stomatitis Virus Genetically Engineered to Express NIS and Human Interferon, in Patients with Relapsed or Refractory Multiple Myeloma, Lymphomas, or Histiocytic/Dendritic Cell Neoplasms

Background: Oncolytic virotherapy, an innovative immunomodulatory therapeutic approach, is currently being investigated for its potential in treating relapsed refractory (R/R) hematologic malignancies. This study focuses on the use of an engineered Vesicular Stomatitis Virus called VSV-IFNβ-NIS, a bullet-shaped rhabdovirus which encodes both interferon beta (IFNβ) and sodium iodine symporter (NIS) with particular tumor cell tropism. Viral IFNβ serves as an indicator of viral proliferation and boosts the host's anti-tumor immune response. This is a phase 1 clinical trial with the identifier NCT03017820, wherein patients (pts) with R/R multiple myeloma (MM), and non-Hodgkin lymphoma (NHL) are treated with a single systemic administration of VSV-IFNβ-NIS. Study Design and Methods: Patient Eligibility Criteria: The Mayo Clinic Institutional Review Board approved the protocol. The study includes adult patients with relapsed or refractory multiple myeloma (MM), or T-cell lymphoma (TCL). For MM or plasmacytoma, patients should have <15% plasma cells and a largest diameter of <5 cm. TCL patients should have a mass <5 cm. Study Design: This is a single-center phase 1 trial aiming to determine the maximum tolerated dose of VSV-IFNβ-NIS in patients with R/R MM, and TCL. Secondary objectives included assessing the safety profile and estimating the clinical response rate of VSV-IFNβ-NIS. Correlative objectives involved monitoring viral replication through plasma IFN-β transgene levels and using SPECT/CT imaging with the NIS gene. Viral genomes were measured through quantitative reverse transcription (qRT) polymerase chain reaction (PCR) of VSV RNA, and any virus shedding was examined in body fluids. The tested doses were 5 × 109 TCID50, 1.7 × 1010, 5 × 1010, and 1.7 × 1011 TCID50. The virus was administered via IV infusion over 30 minutes, and patients received 650 mg acetaminophen and 50 mg diphenhydramine hydrochloride before infusion and every 6 hours for 24 hours to manage fever and hypotension. Two expansion cohorts at DL4 have been added (20 additional PTCL, 10 B-cell lymphoma and histiocytic neoplasms) to obtain additional data on tolerability and efficacy and biomarkers of response in these histologies. Safety and Response Assessments: All patients undergo toxicity evaluation, and adverse events (AEs) assessment using the Common Terminology Criteria for Adverse Events (CTCAE) version 4 criteria, except for cytokine release syndrome (CRS) grading, which follows the 2014 Lee criteria. Dose escalation and tolerability are based on the standard 3+3 phase 1 trial design. Ruxolitinib is added from days 2-5 or day -1 to day 9 depending on the arm to mitigate IFNβ toxicity. Response assessment followed the International Myeloma Working Group criteria for MM and the Lugano Classification for NHL and histiocytic neoplasms. Pharmacodynamic and Pharmacokinetic Analyses: For viremia and viral shedding assessment, RNA is isolated from whole blood, mouth rinse, buccal swabs, and urine samples. Quantitative RT-PCR determined VSV-nucleocapsid (N) RNA copy number, and virus shedding is assessed through coculturing samples on Vero cells. Anti-VSV antibodies are evaluated using the standard plaque reduction neutralization assay. Plasma cytokine levels are measured with a 30-plex human cytokine kit, and human IFN-β levels is quantified using an enzyme-linked immunosorbent assay (ELISA) kit. Statistical Analysis: Incidence of dose-limiting toxicities and AEs are tabulated by dose level (DL). AEs are summarized by type, maximum grade, and duration across patients in each DL. Spearman rank correlation tests are used evaluated correlations between laboratory-based measures, and Wilcoxon rank sum tests compared continuous measures between response groups. Response rates will be summarized by DL and disease group, with estimated response rates and corresponding 95% binomial confidence intervals calculated.

Anti-seed PNAs targeting multiple oncomiRs for brain tumor therapy.

Glioblastoma (GBM) is one of the most lethal malignancies with poor survival and high recurrence rates. Here, we aimed to simultaneously target oncomiRs 10b and 21, reported to drive GBM progression and invasiveness. We designed short (8-mer) γ-modified peptide nucleic acids (sγPNAs), targeting the seed region of oncomiRs 10b and 21. We entrapped these anti-miR sγPNAs in nanoparticles (NPs) formed from a block copolymer of poly(lactic acid) and hyperbranched polyglycerol (PLA-HPG). The surface of the NPs was functionalized with aldehydes to produce bioadhesive NPs (BNPs) with superior transfection efficiency and tropism for tumor cells. When combined with temozolomide, sγPNA BNPs administered via convection-enhanced delivery (CED) markedly increased the survival (>120 days) of two orthotopic (intracranial) mouse models of GBM. Hence, we established that BNPs loaded with anti-seed sγPNAs targeting multiple oncomiRs are a promising approach to improve the treatment of GBM, with a potential to personalize treatment based on tumor-specific oncomiRs.

Trypanosoma cruzi infection induces proliferation and impairs migration of a human breast cancer cell line

Breast cancer is considered the type of cancer that most affects women in the world. The triple negative breast cancer is considered aggressive with poor prognosis. In the 1930s Russian researchers observed that T. cruzi has tropism for tumor cells. Since then, this research field has been subject of a numerous of researches. Here, we proposed to investigate the impact of T. cruzi infection on proliferation and migration of triple negative breast cancer cell line (MDA-MB-231). T. cruzi showed high invasion and multiplication rate in MDA-MB-231 cell line. The infection promoted the multiplication of MDA-MB-231 cell, continuous cell lysis throughout of days of in vitro infection and impaired MDA-MB-231 cell migration. Taken together, these results demonstrated the high susceptibility of MDA-MB-231 cell to T. cruzi and suggested that molecules from T. cruzi may impair host cell migration with potential use to avoid metastasis.

Lamin A/C Mechanosensor Drives Tumor Cell Aggressiveness and Adhesion on Substrates With Tissue-Specific Elasticity.

Besides its structural properties in the nucleoskeleton, Lamin A/C is a mechanosensor protein involved in perceiving the elasticity of the extracellular matrix. In this study we provide evidence about Lamin A/C-mediated regulation of osteosarcoma cell adhesion and spreading on substrates with tissue-specific elasticities. Our working hypothesis is based on the observation that low-aggressive and bone-resident SaOS-2 osteosarcoma cells express high level of Lamin A/C in comparison to highly metastatic, preferentially to the lung, osteosarcoma 143B cells, thereby suggesting a role for Lamin A/C in tumor cell tropism. Specifically, LMNA gene over-expression in 143B cells induced a reduction in tumor cell aggressiveness in comparison to parental cells, with decreased proliferation rate and reduced migration capability. Furthermore, LMNA reintegration into 143B cells changed the adhesion properties of tumor cells, from a preferential tropism toward the 1.5 kPa PDMS substrate (resembling normal lung parenchyma) to the 28 kPa (resembling pre-mineralized bone osteoid matrix). Our study suggests that Lamin A/C expression could be involved in the organ tropism of tumor cells, thereby providing a rationale for further studies focused on the definition of cancer mechanism of metastatization.

Overview of virus and cancer relationships. Position paper.

The role of certain viruses in the etiology of some tumors is today indisputable, but there is a lack, however, of an overview of the relationship between viruses and cancer with a multidisciplinary approach. For this reason, the Health Sciences Foundation has convened a group of professionals from different areas of knowledge to discuss the relationship between viruses and cancer, and the present document is the result of these deliberations. Although viruses cause only 10-15% of cancers, advances in oncology research are largely due to the work done during the last century on tumor viruses. The clearest cancer-inducing viruses are: HPV, HBV, HCV, EBV and, depending on the geographical area, HHV-8, HTLV-1 and HIV. HPVs, for example, are considered to be the causative agents of cervical carcinomas and, more recently, of a proportion of other cancers. Among the Herpes viruses, the association with the development of neoplasms is well established for EBV and HHV-8. Viruses can also be therapeutic agents in certain neoplasms and, thus, some oncolytic viruses with selective tropism for tumor cells have been approved for clinical use in humans. It is estimated that the prophylaxis or treatment of viral infections could prevent at least 1.5 million cancer deaths per year.

Oncolytic herpes simplex virus infects myeloma cells in vitro and in vivo

Because most patients with multiple myeloma (MM) develop resistance to current regimens, novel approaches are needed. Genetically modified, replication-competent oncolytic viruses exhibit high tropism for tumor cells regardless of cancer stage and prior treatment. Receptors of oncolytic herpes simplex virus 1 (oHSV-1), NECTIN-1, and HVEM are expressed on MM cells, prompting us to investigate the use of oHSV-1 against MM. Using oHSV-1-expressing GFP, we found a dose-dependent increase in the GFP+ signal in MM cell lines and primary MM cells. Whereas NECTIN-1 expression is variable among MM cells, we discovered that HVEM is ubiquitously and highly expressed on all samples tested. Expression of HVEM was consistently higher on CD138+/CD38+ plasma cells than in non-plasma cells. HVEM blocking demonstrated the requirement of this receptor for infection. However, we observed that, although oHSV-1 could efficiently infect and kill all MM cell lines tested, no viral replication occurred. Instead, we identified that oHSV-1 induced MM cell apoptosis via caspase-3 cleavage. We further noted that oHSV-1 yielded a significant decrease in tumor volume in two mouse xenograft models. Therefore, oHSV-1 warrants exploration as a novel potentially effective treatment option in MM, and HVEM should be investigated as a possible therapeutic target.

Abstract 5544: Newcastle Disease Virus in human derived tumors: Understanding immune recruitment and activation via virally delivered IL-12

Abstract Oncolytic viruses (OV) are defined by their intrinsic or engineered tropism for tumor cells. Understanding the drivers of susceptibility to infection as well as the downstream intracellular signaling and immune activation profile is critical in identifying the patients that will respond to OV therapy. Newcastle Disease Virus (NDV) is a negative stranded RNA avian paramyxovirus, here modified to encode human GM-CSF or IL-12. Patient derived xenografts (PDX) can more accurately reflect the genetic, epigenetic, and architectural heterogeneity of human tumors and were therefore selected to model the in vivo activity of NDV:GM-CSF. Eighty-nine independent models derived from patients with Bladder, Colorectal, Head and Neck, Kidney, Liver, Lung, Ovarian, Pancreatic, and Breast tumors were studied. Mice were dosed intravenously with NDV:GM-CSF, monitored for pharmacodynamic and pharmacokinetic changes 48 hours after the first dose, and followed for tumor growth inhibition. Objective response was observed in 68% of treated mice, with responses observed in all indications. Using total stranded RNAseq, we were able to assess changes in human tumor, murine immune infiltrate, and viral RNA. Results showed that NDV:GM-CSF treatment leads to increases in transcripts of inflammatory chemokines and cytokines such as RANTES and CXCL9, with induction directly correlated to level of viral replication. Additionally, we saw increases in NKp46 and IL-12R, markers of NK cells. To assess if IL-12 would augment immune activation, we treated surgically resected human tumors with NDV:IL-12. NDV:IL-12 was capable of infecting tumor cells, generating IL-12 protein, and driving a strong IFNγ response. Here we show that NDV can infect a wide variety of human tumors across multiple indications and drive a potent immune activation which can be modulated by transgenes. This data provides insight into what types of tumors could be treated with NDV:GM-CSF or NDV:IL-12. Citation Format: Nicholas M. Durham, Kelly McGlinchey, Shannon Burke, Todd Creasy, Nicola Rath, Noel Monks, Ravinder Tammali, Kevin Schifferli, Nick Holoweckyj, Susie Hayes, Emma Jones, Elizabeth J. Kelly, Danielle Carroll, James Harper, Katie Streicher. Newcastle Disease Virus in human derived tumors: Understanding immune recruitment and activation via virally delivered IL-12 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5544.

Evaluating and manipulating the immune landscape in hepatic verses peritoneal metastases arising from colorectal primary tumors.

568 Background: Colorectal metastases arise predominantly in the liver, lung and peritoneum. It is becoming increasingly clear that these locations might be distinct in terms of tumor cell tropism and genetics. We explored the immunological landscape in primary colorectal tumors along with hepatic and peritoneal metastases. The ultimate intent is to identify opportunities to implore immunomodulatory strategies to improve patient outcomes. Methods: Cancer biopsies were processed to generate tumor-derived organoids and TILs from patients with primary and/or metastatic tumors. These were co-cultured with patient matched TILs to assess immune competency and opportunities to employ checkpoint blockade using an in vitro platform we recently developed to explore TIL activity in patients with rectal cancer prior to standard of care therapy. Results: We found substantively different levels of TILs, their sub-set composition and most importantly their capacity to kill tumor cells. The nature of the metastatic peritoneal and hepatic tumor TILs were distinct. Where high programmed cell death 1 (PD-1) expression was high on TILs there was an opportunity to test PD-1 receptor function with blocking antibodies whereby some TILs showed enhanced cytotoxicity while others did not. Conclusions: Using our immune function assay we have demonstrated the distinct activities of patient-matched TILs in terms of killing at different organ sites of metastases. We also found differences in response to checkpoint inhibition blockade and de novo immune resistance.

Combination of oncolytic viruses and immune checkpoint inhibitors in glioblastoma

Glioblastoma is associated with poor prognosis with a mean survival of 15 months after diagnosis. The current standard of care includes surgery, radiation, and temozolomide with the use of tumor-treating fields in select patient population. The past decade has witnessed a convergence in our understanding of tumor biology and the role of the immune system in fighting cancer. The highly immunosuppressive tumor microenvironment exerted by glioblastoma cells has contributed to the lack of success of novel immunotherapies till date (including checkpoint inhibitors). Oncolytic viral-based approaches are of renewed interest given advances in tumor cell tropism, pathogenicity, and immunogenicity. More importantly, oncolytic viruses have been shown to initiate a broad immune response through various mechanisms including dual activation of the innate and adaptive arms of the host immune system. Because the initial clinical studies with monotherapy checkpoint inhibition in glioblastoma have failed to demonstrate a survival advantage, most trials in glioblastoma are testing combinations that seek to augment the immune response through mutually reinforcing approaches that can overcome the immunosuppressive milieu. Preclinical data in glioblastoma models with combined oncolytic viruses therapy and checkpoint blockade are favorable and provide rationale to initiate first-in-human trials. Even though the number of clinical trials testing this combination in glioblastoma is limited, more studies are expected in the future.

Experimental Adaptation of Rotaviruses to Tumor Cell Lines.

A number of viruses show a naturally extended tropism for tumor cells whereas other viruses have been genetically modified or adapted to infect tumor cells. Oncolytic viruses have become a promising tool for treating some cancers by inducing cell lysis or immune response to tumor cells. In the present work, rotavirus strains TRF-41 (G5) (porcine), RRV (G3) (simian), UK (G6-P5) (bovine), Ym (G11-P9) (porcine), ECwt (murine), Wa (G1-P8), Wi61 (G9) and M69 (G8) (human), and five wild-type human rotavirus isolates were passaged multiple times in different human tumor cell lines and then combined in five different ways before additional multiple passages in tumor cell lines. Cell death caused by the tumor cell-adapted isolates was characterized using Hoechst, propidium iodide, 7-AAD, Annexin V, TUNEL, and anti-poly-(ADP ribose) polymerase (PARP) and -phospho-histone H2A.X antibodies. Multiple passages of the combined rotaviruses in tumor cell lines led to a successful infection of these cells, suggesting a gain-of-function by the acquisition of greater infectious capacity as compared with that of the parental rotaviruses. The electropherotype profiles suggest that unique tumor cell-adapted isolates were derived from reassortment of parental rotaviruses. Infection produced by such rotavirus isolates induced chromatin modifications compatible with apoptotic cell death.

PREVENTION OF COMPLICATIONS IN CASTRATE-REFRACTORY PROSTATE CANCER PATIENTS WITH BONE METASTASES

Abstract: Prostate cancer (PC) is one of the most urgent problems in modern oncourology. Every year the world is recording more than 900 thousands new cases of prostate cancer. For this reason, the diagnosis and treatment of this disease has recently been given more attention, both abroad and in the Russian Federation. Despite improvements in diagnostic methods and implementation of programs for active detection of the disease in its early stages, the number of patients suffering from advanced forms of prostate cancer remains high. Currently, the main method of treatment in patients with metastatic prostate cancer remains the hormone therapy (HT). Patients with metastatic prostate cancer most frequently have localization of metastatic lesions in the lymph nodes and bones. Frequent localization of metastatic lesions in the bones is due to tumor cell tropism of prostate cancer to the bone. Metastatic bone disease, as well as long-term HT conducted in patients with metastatic prostate cancer, leads to irreversible disruption of bone remodeling, which may be accompanied by osteoporosis and fragility fractures. Bone metastases in patients with PC are the most common cause of complications and significantly impair the quality of life of patients. Therapy underlying the prevention of bone complications can be specific, aimed directly at the tumor tissue and non-specific, to strengthen bones and decrease its resorption processes. The article provides an overview of the literature covering the effectiveness of modern drugs, aimed at non-specific prevention of bone complications in patients with metastatic prostate cancer, such as bisphosphonates, and inhibitors of the ligand RANKL, as well as an overview of studies to assess the effectiveness of domestic analogue zolendronovoy acid preparation Resorba in the prevention of osteoporosis.

Emerging role of Natural killer cells in oncolytic virotherapy

Natural killer (NK) cells constitute a subtype of lymphocytes that initiate innate immune responses against tumors and virus-infected cells. The ability of NK cells to kill target cells or to produce cytokines depends on the balance between signals from activating and inhibitory cell-surface receptors. Therapies with NK cells involve activation of endogenous NK cells and/or exogenous transfer by hematopoietic stem cell transplantation/adoptive cell therapy. To exploit the diverse functional abilities of NK cells for cancer immunotherapy, it is important to understand NK cell biology and the underlying regulatory mechanisms. The state of immune suppression prevalent in malignancies creates the need for innovative therapies. Oncolytic viruses are novel anticancer agents showing selective tropism for tumor cells and lacking pathogenicity in humans, but the use of oncolytic virotherapy (OVT) presents multiple challenges. An increasing body of evidence suggests that the host immune response may critically influence the outcome of OVT. Classically, the immune system is thought to limit the efficacy of therapy through virus clearance mediated by innate immune effectors or through adaptive antiviral immune responses eliminating infected cells. Effective strategies do need to be designed in OVT to circumvent the early antiviral activity of NK cells and to augment late NK-cell-mediated antitumor responses. The intrinsic immunostimulating capacity of oncolytic viruses and the possibility of engineering them to express heterologous immunostimulatory molecules (eg, cytokines) support the use of these agents to enhance antitumor immune responses besides inducing direct oncolytic effects. OVT has indeed shown promising therapeutic outcomes in various clinical trials. Here, we review the biology of NK cells, strategies involving NK cells for achieving cancer therapy, and, more particularly, the emerging role of NK cells in OVT.

Structural Characterization of H-1 Parvovirus: Comparison of Infectious Virions to Empty Capsids

The structure of single-stranded DNA (ssDNA) packaging H-1 parvovirus (H-1PV), which is being developed as an antitumor gene delivery vector, has been determined for wild-type (wt) virions and noninfectious (empty) capsids to 2.7- and 3.2-Å resolution, respectively, using X-ray crystallography. The capsid viral protein (VP) structure consists of an α-helix and an eight-stranded anti-parallel β-barrel with large loop regions between the strands. The β-barrel and loops form the capsid core and surface, respectively. In the wt structure, 600 nucleotides are ordered in an interior DNA binding pocket of the capsid. This accounts for ∼12% of the H-1PV genome. The wt structure is identical to the empty capsid structure, except for side chain conformation variations at the nucleotide binding pocket. Comparison of the H-1PV nucleotides to those observed in canine parvovirus and minute virus of mice, two members of the genus Parvovirus, showed both similarity in structure and analogous interactions. This observation suggests a functional role, such as in capsid stability and/or ssDNA genome recognition for encapsulation. The VP structure differs from those of other parvoviruses in surface loop regions that control receptor binding, tissue tropism, pathogenicity, and antibody recognition, including VP sequences reported to determine tumor cell tropism for oncotropic rodent parvoviruses. These structures of H-1PV provide insight into structural features that dictate capsid stabilization following genome packaging and three-dimensional information applicable for rational design of tumor-targeted recombinant gene delivery vectors.

Vascular Endothelial Growth Factor A Promotes Vaccinia Virus Entry into Host Cells via Activation of the Akt Pathway

Vaccinia virus (VV) is an enveloped DNA virus from the poxvirus family and has played a crucial role in the eradication of smallpox. It continues to be used in immunotherapy for the prevention of infectious diseases and treatment of cancer. However, the mechanisms of poxvirus entry, the host factors that affect viral virulence, and the reasons for its natural tropism for tumor cells are incompletely understood. By studying the effect of hypoxia on VV infection, we found that vascular endothelial growth factor A (VEGF-A) augments oncolytic VV cytotoxicity. VEGF derived from tumor cells acts to increase VV internalization, resulting in increased replication and cytotoxicity in an AKT-dependent manner in both tumor cells and normal respiratory epithelial cells. Overexpression of VEGF also enhances VV infection within tumor tissue in vivo after systemic delivery. These results highlight the importance of VEGF expression in VV infection and have potential implications for the design of new strategies to prevent poxvirus infection and the development of future generations of oncolytic VV in combination with conventional or biological therapies.

Oncolytic virotherapy for ovarian cancer.

In the past two decades, more than 20 viruses with selective tropism for tumor cells have been developed as oncolytic viruses (OVs) for treatments of a variety of malignancies. Of these viruses, eleven have been tested in human ovarian cancer models in preclinical studies. So far, nine phase I or II clinical trials have been conducted or initiated using four different types of OVs in patients with recurrent ovarian cancers. In this article, we summarize the different OVs that are being assessed as therapeutics for ovarian cancer. We also present an overview of recent advances in identification of key genetic or immune-response pathways involved in tumorigenesis of ovarian cancer, which provides a better understanding of the tumor specificities and oncolytic properties of OVs. In addition, we discuss how next-generation OVs could be genetically modified or integrated into multimodality regimens to improve clinical outcomes based on recent advances in ovarian cancer biology.

Permissivity of the NCI-60 cancer cell lines to oncolytic Vaccinia Virus GLV-1h68

BackgroundOncolytic viral therapy represents an alternative therapeutic strategy for the treatment of cancer. We previously described GLV-1h68, a modified Vaccinia Virus with exclusive tropism for tumor cells, and we observed a cell line-specific relationship between the ability of GLV-1h68 to replicate in vitro and its ability to colonize and eliminate tumor in vivo.MethodsIn the current study we surveyed the in vitro permissivity to GLV-1h68 replication of the NCI-60 panel of cell lines. Selected cell lines were also tested for permissivity to another Vaccinia Virus and a vesicular stomatitis virus (VSV) strain. In order to identify correlates of permissity to viral infection, we measured transcriptional profiles of the cell lines prior infection.ResultsWe observed highly heterogeneous permissivity to VACV infection amongst the cell lines. The heterogeneity of permissivity was independent of tissue with the exception of B cell derivation. Cell lines were also tested for permissivity to another Vaccinia Virus and a vesicular stomatitis virus (VSV) strain and a significant correlation was found suggesting a common permissive phenotype. While no clear transcriptional pattern could be identified as predictor of permissivity to infection, some associations were observed suggesting multifactorial basis permissivity to viral infection.ConclusionsOur findings have implications for the design of oncolytic therapies for cancer and offer insights into the nature of permissivity of tumor cells to viral infection.

New Perspectives in Cancer Virotherapy: Bringing the Immune System Into Play

Despite constant advances in medically orientated cancer studies, conventional treatments by surgery, chemotherapy or radiotherapy remain partly ineffective against numerous cancers. Oncolytic virotherapy - the use of replication-competent viruses that specifically target tumor cells - has opened up new perspectives for improved treatment of these pathologies. Certain viruses demonstrate a natural, preferential tropism for tumor cells, while others can be genetically modified to show such an effect. Several of these viruses have already been used in preclinical and clinical trials in different tumor models; these studies have provided encouraging results and, thus, confirm the growing interest presented by this therapeutic strategy. The role of the immune system in the efficacy of cancer virotherapy has been poorly documented for a long time; however, several recent reports have presented evidence of synergistic effects between both direct viral oncolysis and the activation of specific, anti-tumor immune responses. These findings offer an exciting outlook for the future of cancer virotherapy.

Diagnostic Tools for Neoplastic Meningitis: Detecting Disease, Identifying Patient Risk, and Determining Benefit of Treatment

Three methods are routinely used to diagnose neoplastic meningitis (NM): clinical signs and symptoms, cerebrospinal fluid (CSF) cytology, and magnetic resonance imaging (MRI) of the brain and spine. Clinical manifestations are often subtle or may be ascribed to other cancer complications, eg, treatment-related disorders or brain parenchymal metastases. CSF cytology has a high specificity (>95%), but its sensitivity is generally less than 50%. MRI sensitivity and specificity vary with the type of primary cancer; overall, MRI findings consistent with leptomeningeal disease are detected in fewer than 50% of NM patients. While most clinicians evaluate CSF cytology along with MRI and the clinical examination, underdiagnosis is a major problem, since many patients are both cytologically and radiographically negative. Failure to consider NM in the differential diagnosis magnifies the problem of underdiagnosis. CSF flow cytometry is particularly promising for evaluating NM from hematologic cancers, with a diagnostic sensitivity many fold greater than conventional cytology. Research has focused on identifying biochemical markers of tumor cells in the CSF. For example, molecules involved in CNS penetration (eg, matrix metalloproteinases and cathepsins), tumor cell tropism (eg, chemokines CXCL8 and CCL18), and angiogenesis (eg, vascular endothelial growth factor) are elevated in the CSF of patients with NM. Evidence that some tumor types are more likely to infiltrate the CNS also has stimulated research into primary tumor markers predictive of CNS metastases. At present, there is no tumor marker or patient characteristic that reliably predicts the development of NM, and diagnosis still relies on suggestive signs and symptoms, positive CSF cytology, or a consistent MRI-all late manifestations of NM. Until techniques capable of detecting NM early are developed, increased awareness of the disease and standardized evaluation are likely to have the greatest impact on improving diagnosis and implementing earlier treatment.

Recombinant Oncolytic Poliovirus Eliminates Glioma In Vivo Without Genetic Adaptation to a Pathogenic Phenotype

Many viruses, either naturally occurring or as a result of genetic manipulation, exhibit conditional replication in transformed cells. This principle is the basis for experimental therapeutic approaches exploiting the oncolytic potential of such agents without the danger of collateral damage to resistant normal tissues. One of the potential obstacles to these approaches is the possibility of genetic adaptation of oncolytic viruses upon replication in susceptible tumor tissues. Genetic variation can reverse genetic manipulations of parental viral genomes that determine attenuation of virulence, selective tumor cell tropism or other desirable traits. Alternatively, it may convey new properties not originally associated with parental strains, e.g., adaptation to a human host range. We examined genetic stability of an oncolytic nonpathogenic poliovirus recombinant considered for therapy of recurrent glioblastoma multiforme (GBM). This was done by serial passage experiments in glioma xenografts in vivo and investigation of phenotypic and genotypic markers of attenuation. Intratumoral inoculation of oncolytic poliovirus produced efficient tumor regress and elimination without altering temperature-sensitive growth, selective cytotoxicity, or genetic markers of attenuation of virus recovered from inoculated animals. Our studies demonstrate that active viral oncolysis of malignant glioma does not alter the conditional replication properties of oncolytic nonpathogenic poliovirus recombinants.

Oncolytic Virotherapy Synergism with Signaling Inhibitors: Rapamycin Increases Myxoma Virus Tropism for Human Tumor Cells

Myxoma virus is a rabbit-specific poxvirus pathogen that also exhibits a unique tropism for human tumor cells and is dramatically oncolytic for human cancer xenografts. Most tumor cell lines tested are permissive for myxoma infection in a fashion intimately tied to the activation state of Akt kinase. A host range factor of myxoma virus, M-T5, directly interacts with Akt and mediates myxoma virus tumor cell tropism. mTOR is a regulator of cell growth and metabolism downstream of Akt and is specifically inhibited by rapamycin. We report that treatment of nonpermissive human tumor cell lines, which normally restrict myxoma virus replication, with rapamycin dramatically increased virus tropism and spread in vitro. This increased myxoma replication is concomitant with global effects on mTOR signaling, specifically, an increase in Akt kinase. In contrast to the effects on human cancer cells, rapamycin does not increase myxoma virus replication in rabbit cell lines or permissive human tumor cell lines with constitutively active Akt. This indicates that rapamycin increases the oncolytic capacity of myxoma virus for human cancer cells by reconfiguring the internal cell signaling environment to one that is optimal for productive virus replication and suggests the possibility of a potentially therapeutic synergism between kinase signaling inhibitors and oncolytic poxviruses for cancer treatment.