Personalizing oncolytic virotherapy?
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Animals↗
Biomedical subjects
E Antonio Chiocca
Publications and source records attributed to E Antonio Chiocca.
GNOSIS: guidelines for neuro-oncology: standards for investigational studies--reporting of surgically based therapeutic clinical trials.
We present guidelines to standardize the reporting of surgically based neuro-oncology trials. The guidelines are summarized in a checklist format that can be used as a framework from which to construct a surgically based trial. This manuscript follows and is taken in part from GNOSIS: Guidelines for neuro-oncology: Standards for investigational studies-reporting of phase 1 and phase 2 clinical trials [Chang SM, Reynolds SL, Butowski N, Lamborn KR, Buckner JC, Kaplan RS, Bigner DD (2005) Neuro-oncology 7:425-434].
Clinical Trials as Topic↗
Cyclophosphamide increases transgene expression mediated by an oncolytic adenovirus in glioma-bearing mice monitored by bioluminescence imaging.
Approaches to improve the oncolytic potency of replication-competent adenoviruses include the insertion of therapeutic transgenes into the viral genome. Little is known about the levels and duration of in vivo transgene expression by cells infected with such "armed" viruses. Using a tumor-selective adenovirus encoding firefly luciferase (AdDelta24CMV-Luc) we investigated these questions in an intracranial mouse model for malignant glioma. Luciferase expression was detected by bioluminescence imaging, and the effect of the immunosuppressive agent cyclophosphamide (CPA) on transgene expression was assessed. Intratumoral AdDelta24CMV-Luc injection led to a localized dose-dependent expression of luciferase. Surprisingly, this expression decreased rapidly during the course of 14 days. In contrast, mice injected with nonreplicating Ad.CMV-Luc demonstrated stable transgene expression. Treatment of mice with CPA in combination with AdDelta24CMV-Luc retarded the loss of transgene expression. Staining of mouse brains for inflammatory cells demonstrated decreased tumor infiltration by immune cells in CPA-treated mice. Moreover, in immunodeficient NOD/SCID mice loss of transgene expression was less rapid and not prevented by CPA treatment. Together, our data demonstrate that transgene expression and viral replication decrease rapidly after intratumoral injection of oncolytic adenovirus in mouse brains and that treatment with the immunomodulator CPA prolongs viral-mediated gene expression.
Adenoviridae↗
Tumor stromal-derived factor-1 recruits vascular progenitors to mitotic neovasculature, where microenvironment influences their differentiated phenotypes.
Mechanisms underlying tumor vasculogenesis, the homing and engraftment of bone marrow-derived vascular progenitors, remain undefined. We hypothesized that tumor cell-secreted factors regulate vasculogenesis. We studied vasculogenic and nonvasculogenic intracranial murine gliomas. A PCR screen identified stromal-derived factor-1 (SDF-1/CXCL12) and vascular endothelial growth factor (VEGF) expression by vasculogenic glioma cells and spontaneously arising vasculogenic tumors in NF1+/-:Trp53+/- mice, but not by nonvasculogenic glioma cells. Enforced SDF-1, not VEGF, expression in nonvasculogenic cells caused vasculogenesis. Combined SDF-1 and VEGF expression augmented vasculogenesis over SDF-1 expression alone. Blocking SDF-1 receptor CXCR4 reduced short-term homing and long-term engraftment of vascular progenitors. Implanting tumor cells secreting SDF-1 was therefore necessary and sufficient to incorporate marrow-derived precursors into tumor endothelium. SDF-1 seemed to exert these effects by acting locally intratumorally and did not cause an efflux of marrow-derived progenitors into circulation. Tumor microenvironment determined additional fates of marrow-derived cells. Hypoxia, observed with ectopic s.c. murine tumors at levels approximating that of intracranial human glioblastoma, interacted with tumor-secreted SDF-1 to expand engrafted vascular progenitor differentiated phenotypes to include pericytes as well as endothelium. In contrast, less hypoxic orthotopic intracranial murine gliomas contained only marrow-derived endothelium without marrow-derived pericytes. Furthermore, we found that vasculogenesis is significant for tumors because it generates endothelium with a higher mitotic index than endothelium derived from local sources. Although CXCR4 blockade selectively targeted endothelium generated by vasculogenesis, completely inhibiting vessel formation may require combination therapy targeting locally derived and marrow-derived endothelium.
Animals↗
Cyclophosphamide enhances glioma virotherapy by inhibiting innate immune responses.
Clinical trials are testing oncolytic viruses (OVs) as therapies for cancer. We have shown that animals that have brain tumors and are treated with a herpes simplex virus (HSV)-derived OV live significantly longer when cyclophosphamide (CPA) is preadministered. Here, we explore the mechanisms behind this finding. In a syngeneic rat glioma model, intratumoral HSV administration is associated with rapid increase of natural killer cells, microglia/macrophages (CD68+ and CD163+), and IFN-gamma. Pretreatment with CPA enhances HSV replication and oncolysis and reduces an HSV-mediated increase in CD68+ and CD163+ cells and intratumoral IFN-gamma. Molecular imaging shows CPA pretreatment to inhibit HSV-induced infiltration of tumor-associated phagocytic cells. Our results reveal molecular and cellular mechanisms that inhibit intratumoral spread of HSV and suggest a therapeutic path for improving the efficacy of virotherapy as a treatment for cancer.
Animals↗
Gene therapy for glioblastoma.
Established treatments such as surgery, radiation, and chemotherapy have only minimally altered the median survival time of patients with glioblastoma multiforme, the most common malignant brain tumor. These failures reflect the highly invasive nature of the disease, as well as the fact that few cells are actively dividing at any given time. As a result, therapies need to act in areas of the brain that are spatially separated from the site of tumor origin and over extended periods of time temporally separated from their introduction. Over the past decade, laboratory studies and early clinical trials have raised the hope that these therapeutic requirements may be fulfilled by gene therapy in which nonreplicating transgene-bearing viruses, oncolytic viruses, or migratory stem cells are used to deliver tumoricidal transgenes. The authors review the principles behind these approaches and their initial results.
Brain Neoplasms↗
Glioma virotherapy: effects of innate immune suppression and increased viral replication capacity.
Oncolytic viruses are genetically altered replication-competent viruses that infect, and reproduce in, cancer cells but do not harm normal cells. On lysis of the infected cells, the newly formed viruses burst out and infect other tumor cells. Experiments with injecting mutant herpes simplex virus 1 (hrR3) into glioma implanted in brains of rats show lack of efficacy in eradicating the cancer. This failure is attributed to interference by the immune system. Initial pretreatment with immunosuppressive agent cyclophosphamide reduces the percentage of immune cells. We introduce a mathematical model and use it to determine how different protocols of cyclophosphamide treatment and how increased burst size of the mutated virus will affect the growth of the cancer. One of our conclusions is that the diameter of the cancer will decrease from 4 mm to eventually 1 mm if the burst size of the virus is triple that which is currently available. The effect of repeated cyclophosphamide treatment is to maintain a low density of uninfected cells in the tumor, thus reducing the probability of migration of tumor cells to other locations in the brain.
Animals↗
Brain tumor imaging and surgical management: the neurosurgeon's perspective.
Advances in imaging technologies have influenced neurosurgical techniques and decisions and have enabled previously impossible resections, and neurosurgeons rely on the various modalities to make surgery as safe as possible. We look at the different technologies that have developed and how they are used by neurosurgeons, in combination with the knowledge of anatomy, to evaluate brain and spinal tumors and make surgical decisions that improve treatment outcomes.
Angiography↗
Gene therapeutics: the future of brain tumor therapy?
Primary glioblastoma multiforme is an aggressive brain tumor that has no cure. Current treatments include gross resection of the tumor, radiation and chemotherapy. Despite valiant efforts, prognosis remains dismal. A promising new technique involves the use of oncolytic viruses that can specifically replicate and lyse in cancers, without spreading to normal tissues. Currently, these are being tested in relevant preclinical models and clinical trials as a therapeutic modality for many types of cancer. Results from recent clinical trials with oncolytic viruses have revealed the safety of this approach, although evidence for efficacy remains elusive. Oncolytic viral strategies are summarized in this review, with a focus on therapies used in brain tumors.
Brain Neoplasms↗
Cyclophosphamide allows for in vivo dose reduction of a potent oncolytic virus.
The success of cancer virotherapy depends on its efficacy versus toxicity profile in human clinical trials. Progress towards clinical trials can be hampered by the relatively elevated doses of oncolytic viruses administered in animal models to achieve an anticancer effect and by the even higher doses required in humans to approximate an animal bioequivalent dose. Such elevated doses of injected viral proteins may also lead to undesirable toxicities and are also very difficult to produce in a biotechnological setting. We report that a relatively potent herpes simplex virus type 1 oncolytic virus (rQNestin34.5) produces 45% survivors at a dose of 3 x 10(4) plaque-forming units (pfu) in a 9-day-old mouse model of human glioma. Unlike our previous findings with less potent oncolytic viruses, though, the preadministration of cyclophosphamide did not enhance this survival or affect oncolytic virus tumor distribution and tumor volume. However, when oncolytic virus doses were reduced (3 x 10(3) and 3 x 10(2) pfu), cyclophosphamide significantly enhanced both animal survival and oncolytic virus tumor distribution and also reduced tumor volumes. These findings thus show that cyclophosphamide allows for dose reduction of doses of a relatively potent oncolytic virus, a finding with implications for the development of clinical trials.
Animals↗
Tissue inhibitor of metalloproteinase-3 expression from an oncolytic adenovirus inhibits matrix metalloproteinase activity in vivo without affecting antitumor efficacy in malignant glioma.
Oncolytic adenoviruses exhibiting tumor-selective replication are promising anticancer agents. Insertion and expression of a transgene encoding tissue inhibitor of metalloproteinase-3 (TIMP-3), which has been reported to inhibit angiogenesis and tumor cell infiltration and induce apoptosis, may improve the antitumor activity of these agents. To assess the effects of TIMP-3 gene transfer to glioma cells, a replication-defective adenovirus encoding TIMP-3 (Ad.TIMP-3) was employed. Ad.TIMP-3 infection of a panel of glioma cell cultures decreased the proliferative capacity of these cells and induced morphologic changes characteristic for apoptosis. Next, a conditionally replicating adenovirus encoding TIMP-3 was constructed by inserting the TIMP-3 expression cassette into the E3 region of the adenoviral backbone containing a 24-bp deletion in E1A. This novel oncolytic adenovirus, AdDelta24TIMP-3, showed enhanced oncolytic activity on a panel of primary cell cultures and two glioma cell lines compared with the control oncolytic virus AdDelta24Luc. In vivo inhibition of matrix metalloproteinase (MMP) activity by AdDelta24TIMP-3 was shown in s.c. glioma xenografts. The functional activity of TIMP-3 was imaged noninvasively using a near-IR fluorescent MMP-2-activated probe. Tumoral MMP-2 activity was significantly reduced by 58% in the AdDelta24TIMP-3-treated tumors 24 hours after infection. A study into the therapeutic effects of combined oncolytic and antiproteolytic therapy was done in both a s.c. and an intracranial model for malignant glioma. Treatment of s.c. (U-87MG) or intracranial (U-87deltaEGFR) tumors with AdDelta24TIMP-3 and AdDelta24Luc both significantly inhibited tumor growth and prolonged survival compared with PBS-treated controls. However, expression of TIMP-3 in the context of AdDelta24 did not significantly affect the antitumor efficacy of this oncolytic agent.
Adenoviridae↗
Contribution of bone marrow-derived cells to blood vessels in ischemic tissues and tumors.
Vessels are formed during embryonic development through three distinct processes. Angiogenesis and arteriogenesis involve the remodeling of established capillary networks and arterioles, while vasculogenesis involves the differentiation of mesodermal progenitor cells called angioblasts into mature endothelial cells. Until recently, postnatal vessel development was felt to occur exclusively through angiogenesis or arteriogenesis. However, recent studies using experimental tumor and ischemia models have raised controversy regarding whether vasculogenesis occurs in postnatal vessel development, with some studies suggesting the possibility and others refuting it. Here, we summarize the process of embryonic vessel development and review studies investigating the role of postnatal vasculogenesis in vessel formation in adult ischemia and tumors. We then focus on studies in which wild-type and genetically modified vascular progenitor cells have been investigated as possible cellular therapies for tumors or ischemia. We also take note of key issues that will need to be understood about the biology of vasculogenesis before cellular therapies utilizing vascular progenitor cells can be finally taken from the bench to the bedside.
Animals↗
Brain tumor oncolysis with replication-conditional herpes simplex virus type 1 expressing the prodrug-activating genes, CYP2B1 and secreted human intestinal carboxylesterase, in combination with cyclophosphamide and irinotecan.
The treatment of malignant glioma is currently ineffective. Oncolytic viruses are being explored as a means to selectively lyse tumor cells in the brain. We have engineered a mutant herpes simplex virus type 1 with deletions in the viral UL39 and gamma(1)34.5 genes and an insertion of the two prodrug activating genes, CYP2B1 and secreted human intestinal carboxylesterase. Each of these can convert the inactive prodrugs, cyclophosphamide and irinotecan (CPT-11), into their active metabolites, respectively. This new oncolytic virus (MGH2) displays increased antitumor efficacy against human glioma cells both in vitro and in vivo when combined with cyclophosphamide and CPT-11. Importantly, cyclophosphamide, CPT-11, or the combination of cyclophosphamide and CPT-11 does not significantly affect oncolytic virus replication. Therefore, MGH2 provides effective multimodal therapy for gliomas in preclinical models when combined with these chemotherapy agents.
Antineoplastic Combined Chemotherapy Protocols↗
An oncolytic HSV-1 mutant expressing ICP34.5 under control of a nestin promoter increases survival of animals even when symptomatic from a brain tumor.
Oncolytic herpes simplex virus-1 (HSV-1) mutants possessing mutations in the ICP34.5 and ICP6 genes have proven safe through clinical trials. However, ICP34.5-null viruses may grow poorly in cells due to their inability to prevent host-cell shut-off of protein synthesis caused by hyperphosphorylation of eukaryotic initiation factor 2alpha. To increase tumor selectivity, glioma-selective expression of ICP34.5 in the context of oncolysis may be useful. Malignant gliomas remain an incurable disease. One molecular marker of malignant gliomas is expression of the intermediate filament nestin. Expression of nestin mRNA was confirmed in 6 of 6 human glioma lines and in 3 of 4 primary glioma cells. Normal human astrocytes were negative. A novel glioma-selective HSV-1 mutant (rQNestin34.5) was thus engineered by expressing ICP34.5 under control of a synthetic nestin promoter. Replication, cellular propagation, and cytotoxicity of rQNestin34.5 were significantly enhanced in cultured and primary human glioma cell lines compared with control virus. However, replication, cellular propagation, and cytotoxicity of rQNestin34.5 in normal human astrocytes remained quantitatively similar to that of control virus. In glioma cell lines infected with rQNestin34.5, the level of phospho-eukaryotic initiation factor 2alpha was lower than that of cells infected by control rHsvQ1, confirming selective ICP34.5 expression in glioma cells. In vivo, rQNestin34.5 showed significantly more potent inhibition of tumor growth compared with control virus. Treatment in the brain tumor model was instituted on animal's display of neurologic symptoms, which usually led to rapid demise. rQNestin34.5 treatment doubled the life span of these animals. These results show that rQNestin34.5 could be a potent agent for the treatment of malignant glioma.
Animals↗
A phase I open-label, dose-escalation, multi-institutional trial of injection with an E1B-Attenuated adenovirus, ONYX-015, into the peritumoral region of recurrent malignant gliomas, in the adjuvant setting.
ONYX-015 is an oncolytic virus untested as a treatment for malignant glioma. The NABTT CNS Consortium conducted a dose-escalation trial of intracerebral injections of ONYX-015. Cohorts of six patients at each dose level received doses of vector from 10(7) plaque-forming units (pfu) to 10(10) pfu into a total of 10 sites within the resected glioma cavity. Adverse events were identified on physical exams and testing of hematologic, renal, and liver functions. Efficacy data were obtained from serial MRI scans. None of the 24 patients experienced serious adverse events related to ONYX-015. The maximum tolerated dose was not reached at 10(10) pfu. The median time to progression after treatment with ONYX-015 was 46 days (range 13 to 452 + days). The median survival time was 6.2 months (range 1.3 to 28.0 + months). One patient has not progressed and 1 patient showed regression of interval-increased enhancement. With more than 19 months of follow-up, 1/6 recipients at a dose of 10(9) and 2/6 at a dose of 10(10) pfu remain alive. In 2 patients who underwent a second resection 3 months after ONYX-015 injection, a lymphocytic and plasmacytoid cell infiltrate was observed. Injection of ONYX-015 into glioma cavities is well tolerated at doses up to 10(10) pfu.
Adenoviridae↗
Altered expression of antiviral cytokine mRNAs associated with cyclophosphamide's enhancement of viral oncolysis.
Oncolytic viruses (OVs) are being used as anticancer agents in preclinical and clinical trials. Propagation of OVs inside infected tumors is critical to their efficacy and is mediated by the productive generation of progeny OVs within infected tumor cells. In turn, this progeny can spread the infection to other tumor cells in successive rounds of oncolysis. Previously, we had found that, in rats, cyclophosphamide (CPA) pretreatment increased infection of brain tumors by an intra-arterially administered herpes simplex virus type 1 OV, because it inhibited activation of complement responses, mediated by innate IgM. We also have previously shown that other pharmacologic inhibitors of complement, such as cobra venom factor (CVF), allowed for increased infection. However, in these studies, further inhibition of complement responses by CVF did not result in additional infection of brain tumor cells or in propagation of OV to surrounding tumor cells. In this study, we sought to determine if CPA did lead to increased infection/propagation from initially infected tumor cells. Unlike our results with CVF, we find that CPA administration does result in a time-dependent increase in infection of tumor cells, suggestive of increased propagation, in both syngeneic and athymic models of brain tumors. This increase was due to increased survival of OV within infected tumors and brain surrounding tumors. CPA's effect was not due to a direct enhancement of viral replication in tumor cells, rather was associated with its immunosuppressive effects. RT-PCR analysis revealed that CPA administration resulted in impaired mRNA production by peripheral blood mononuclear cells (PBMCs) of several cytokines (interferons alpha/beta, interferon gamma, TNFalpha, IL-15, and IL-18) with anti-HSV function. These findings suggest that the CPA-mediated facilitation of OV intraneoplastic propagation is associated with a general decrease of antiviral cytokines mRNAs in PBMCs. These findings not only suggest a potential benefit for the addition of transient immunosuppression in clinical applications of oncolytic HSV therapy, but also suggest that innate immunomodulatory pathways may be amenable to manipulation, in order to increase OV propagation and survival within infected tumors.
Animals↗
Cytochrome p450-based gene therapies for cancer.
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Animals↗