Oncolytic Adenovirus for the Targeting of Paclitaxel-Resistant Breast Cancer Stem Cells

Adjuvant systemic therapies effectively reduce the risk of breast cancer recurrence and metastasis, but therapy resistance can develop in some patients due to breast cancer stem cells (BCSCs). Oncolytic adenovirus (OAd) represents a promising therapeutic approach as it can specifically target cancer cells. However, its potential to target BCSCs remains unclear. Here, we evaluated a Cox-2 promoter-controlled, Ad5/3 fiber-modified OAd designed to encode the human sodium iodide symporter (hNIS) in breast cancer models. To confirm the potential of OAds to target BCSCs, we employed BCSC-enriched estrogen receptor-positive (ER+) paclitaxel-resistant (TaxR) cells and tumorsphere assays. OAd-hNIS demonstrated significantly enhanced binding and superior oncolysis in breast cancer cells, including ER+ cells, while exhibiting no activity in normal mammary epithelial cells. We observed improved NIS expression as the result of adenovirus death protein deletion. OAd-hNIS demonstrated efficacy in targeting TaxR BCSCs, exhibiting superior killing and hNIS expression compared to the parental cells. Our vector was capable of inhibiting tumorsphere formation upon early infection and reversing paclitaxel resistance in TaxR cells. Importantly, OAd-hNIS also destroyed already formed tumorspheres seven days after their initiation. Overall, our findings highlight the promise of OAd-hNIS as a potential tool for studying and targeting ER+ breast cancer recurrence and metastasis.

Interferon-expressing oncolytic adenovirus + chemoradiation inhibited pancreatic cancer growth in a hamster model

Past clinical trials of adjuvant therapy combined with interferon (IFN) alpha, fluorouracil, cisplatin, and radiation improved the 5-year survival rate of pancreatic ductal adenocarcinoma (PDAC). However, these trials also revealed the disadvantages of the systemic toxicity of IFN and insufficient delivery of IFN. To improve efficacy and tolerability, we have developed an oncolytic adenovirus-expressing IFN (IFN-OAd). Here, we evaluated IFN-OAd in combination with chemotherapy (gemcitabine + nab-paclitaxel) + radiation. Combination index (CI) analysis showed that IFN-OAd + chemotherapy + radiation was synergistic (CI <1). Notably, IFN-OAd + chemotherapy + radiation remarkably suppressed tumor growth and induced a higher number of tumor-infiltrating lymphocytes without severe side toxic effects in an immunocompetent and adenovirus replication-permissive hamster PDAC model. This is the first study to report that gemcitabine + nab-paclitaxel, the current first-line chemotherapy for PDAC, did not hamper virus replication in a replication-permissive immunocompetent model. IFN-OAd has the potential to overcome the barriers to clinical application of IFN-based therapy through its tumor-specific expression of IFN, induction of antitumor immunity, and sensitization with chemoradiation. Combining IFN-OAd with gemcitabine + nab-paclitaxel + radiation might be an effective and clinically beneficial treatment for PDAC patients.

Viral Shedding in Mice following Intravenous Adenovirus Injection: Impact on Biosafety Classification

There have been numerous advances in gene therapy and oncolytic virotherapy in recent years, especially with respect to cutting-edge animal models to test these novel therapeutics. With all of these advances, it is important to understand the biosafety risks of testing these vectors in animals. We performed adenovirus-based viral shedding studies in murine models to ascertain when it is appropriate to downgrade the animals from Biosafety Level (BSL) 2 to BSL 1 for experimental handling and transport. We utilized intravenous injections of a replication-competent adenovirus and analyzed viral shedding via the collection of buccal and dermal swabs from each animal, in addition to obtaining urine and stool samples. The adenovirus hexon copy number was determined by qPCR, and plaque formation was analyzed to assess the biologic activity of viral particles. Our results demonstrate that after 72 h following viral inoculation, there is no significant quantity of biologically active virus shedding from the animals. This observation suggests that on day 4 following adenovirus injection, mice can be safely downgraded to BSL 1 for the remainder of the experiment with no concern for hazardous exposure to laboratory personnel.

Infectivity-Enhanced, Conditionally Replicative Adenovirus for COX-2-Expressing Castration-Resistant Prostate Cancer

BACKGROUND

The development of conditionally replicative adenoviruses (CRAds) for castration-resistant prostate cancer (CRPC), particularly neuroendocrine prostate cancer (NEPC), has two major obstacles: choice of control element and poor infectivity. We applied fiber-modification-based infectivity enhancement and an androgen-independent promoter (cyclooxynegase-2, COX-2) to overcome these issues.

METHODS

The properties of the COX-2 promoter and the effect of fiber modification were tested in two CRPC cell lines (Du-145 and PC3). Fiber-modified COX-2 CRAds were tested in vitro for cytocidal effect as well as in vivo for antitumor effect with subcutaneous CRPC xenografts.

RESULTS

In both CRPC cell lines, the COX-2 promoter showed high activity, and Ad5/Ad3 fiber modification significantly enhanced adenoviral infectivity. COX-2 CRAds showed a potent cytocidal effect in CRPC cells with remarkable augmentation by fiber modification. In vivo, COX-2 CRAds showed an antitumor effect in Du-145 while only Ad5/Ad3 CRAd showed the strongest antitumor effect in PC3.

CONCLUSION

COX-2 promoter-based, infectivity-enhanced CRAds showed a potent antitumor effect in CRPC/NEPC cells.

Development of Oncolytic Vectors Based on Human Adenovirus Type 6 for Cancer Treatment

Human Adenovirus type 6 (HAdV-C6) is a promising candidate for the development of oncolytic vectors as it has low seroprevalence and the intrinsic ability to evade tissue macrophages. However, its further development as a therapeutic agent is hampered by the lack of convenient cloning methods. We have developed a novel technology when a shuttle plasmid carrying the distal genome parts with modified E1A and E3 regions is recombined in vitro with the truncated HAdV-C6 genome. Using this approach, we have constructed a novel Ad6-hT-GM vector controlled by the hTERT promoter and expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) instead of 6.7K and gp19K E3 proteins. We have demonstrated that control by the hTERT promoter may result in delayed viral replication, which nevertheless does not significantly change the cytotoxic ability of recombinant viruses. The insertion of the transgene by displacing the E3-6.7K/gp19K region does not drastically change the expression patterns of E3 genes; however, mild changes in expression from major late promoter were observed. Finally, we have demonstrated that the treatment of human breast cancer xenografts in murine models with Ad6-hT-GM significantly decreased the tumor volume and improved survival time compared to mock-treated mice.

Efficacy of photodynamic therapy in women with HSIL, LSIL and early stage squamous cervical cancer: a systematic review and meta-analysis

BACKGROUND

We sought to conduct a systematic review and meta-analysis of randomized and non-randomized clinical trials to assess the efficacy of photodynamic therapy (PDT) in cervical epithelial neoplasia (CIN) and early-stage cervical cancer. Additionally, according to the results, we tried to consider which stage of CIN is more sensitive to PDT.

METHODS

A systematic search was conducted using electronic databases including PubMed, ClinicalTrials.gov, the Cochrane Library, and Google Scholar.

INCLUSION CRITERIA

all patients had confirmed low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL), or an early-stage cervical cancer - the cancer is less than 3 mm deep into the cervix -IA; type of photosensitizer and any type of wavelength.

EXCLUSION CRITERIA

women who were previously treated with PDT; Risk of bias assessment was carried out for each study included in the systematic review using the Cochrane Handbook for Systematic Reviews of Interventions: RoB-2 was used to assess the risk of bias in randomized studies, while ROBINS-I - in non-randomized ones.

RESULTS

We identified 2213 publications, but only 6 met the inclusion criteria and were included in the synthesis. PDT is most effective when patients have CIN 2 or photosensitizer is administered intravenously.

CONCLUSION

Based on our systematic review and meta-analysis, it could be concluded that photodynamic therapy may be a practical approach in CIN (LSIL) regression compared with placebo. Nevertheless, we need more evidence and long-term follow-up to answer all questions thoroughly.

Interferon Alpha-Expressing Oncolytic Adenovirus for Treatment of Esophageal Adenocarcinoma

INTRODUCTION

Esophageal adenocarcinoma (EAC) has increased in incidence in Western countries, and its poor prognosis necessitates the development of novel therapeutics. We previously reported the potential of conditionally replicative adenoviruses (CRAd) as a novel therapeutic treatment for this disease. To further augment the therapeutic effectiveness of our cyclooxygenase-2 (Cox2) controlled CRAd in EAC, we inserted an interferon alpha (IFN) transgene into the viral genome that is expressed upon viral replication. In this manuscript, we analyze the cytotoxic and oncolytic effects of an IFN-expressing oncolytic adenovirus in EAC and the role of the Cox2 promoter in providing for selective replication in human tissues.

METHODS

An infectivity-enhanced IFN-expressing CRAd (5/3 Cox2 CRAd ΔE3 ADP IFN) and other control viruses were first tested in vitro with cell lines. For the in vivo study, EAC xenografts in nude mice were treated with a single intratumoral dose of virus. An ex vivo analysis with live tissue slices was conducted using surgically resected EAC patient specimens.

RESULTS

Expression of IFN significantly enhanced the cytotoxic and oncolytic effect of a Cox2-promoter controlled CRAd. This virus showed significant tumor growth suppression in a xenograft model. Furthermore, in human EAC samples, the promoter-controlled virus demonstrated selective replication in cancerous tissues, leaving normal esophageal tissue unaffected.

CONCLUSION

An IFN-expressing CRAd driven by the Cox2 promoter has strong oncolytic effects as well as cancer-specific replication. Our novel vector possesses critical characteristics that make it a potential candidate for clinical translation to treat EAC.

Cancer imaging and therapy utilizing a novel NIS-expressing adenovirus: The role of adenovirus death protein deletion

Encoding the sodium iodide symporter (NIS) by an adenovirus (Ad) is a promising strategy to facilitate non-invasive imaging and radiotherapy of pancreatic cancer. However, insufficient levels of NIS expression in tumor cells have limited its clinical translation. To optimize Ad-based radiotherapy and imaging, we investigated the effect of Ad death protein (ADP) deletion on NIS expression. We cloned two sets of oncolytic NIS-expressing Ads that differed only in the presence or absence of ADP. We found that ADP expression negatively affected NIS membrane localization and inhibited radiotracer uptake. ADP deletion significantly improved NIS-based imaging in pancreatic cancer models including patient-derived xenografts, where effective imaging was possible for up to 6 weeks after a single virus injection. This study demonstrates that improved oncolysis may hinder the therapeutic effect of oncolytic viruses designed to express NIS. In vivo studies in combination with ¹³¹I showed potential for effective radiotherapy. This also highlights the need for further investigation into optimal timing of ¹³¹I administration and suggests that repeated doses of ¹³¹I should be considered to improve efficacy in clinical trials. We conclude that ADP deletion is essential for effective NIS-based theranostics in cancer.

Abstract 5914: The porcine model for onocolytic adenovirus-based therapy

Oncolytic adenoviruses (Ad) are promising tools in the development of cancer therapeutics. A majority of Ad-based therapies utilize serotypes of species C, with Adenovirus type 5 (Ad5) being the most commonly employed. Previously, clinical trials have demonstrated the low efficiency of Ad5 vectors, mainly due to absence of the Ad5 primary receptor (Coxsackie Adenovirus Receptor, CAR) in cancer cells. Engineering Ad vectors utilizing the species B (Ad3, Ad35, Ad11) receptors have greatly improved the oncolytic potential of Ad-based therapies. However, the lack of a viable animal model has impeded clinical translation of these tropism-modified vectors. Mouse models are insufficient because Ad does not replicate in murine tissue. Non-human apes are not feasible due to availability and cost. Cotton rats and Syrian hamsters, although permissive of Ad5 replication, are not suitable for Ad3-, Ad35-, and Ad11-retargeted vectors due to the lack of species B primary receptors (CD46 and desmoglein 2) in rodent systems. In this study, we explored pigs as a model to study performance of the group B oncolytic adenoviruses by employing the fiber-modified Ad5/Ad3 chimeric vector. As a control, the Ad5 fiber-unmodified virus was used. First, we demonstrated the ability of swine cell lines to support replication of both Ad5 and Ad5/Ad3. Second, we analyzed binding, gene transfer, cytolytic, and replication ability of Ad5 and Ad5/Ad3 in various non-human cell lines (swine, hamster, murine, rat, bovine, canine). Our data confirmed that while hamster cell lines (HP1 and HapT1) were able to support binding and replication of Ad5-based vectors, they failed to support that with the Ad3-retargeted vectors. Additionally, we showed that among all tested cell lines, only porcine cells (PK15 and PTK75) were supportive of both binding and replication of the Ad3-retargeted virus. Of note, Ad5/Ad3 outperformed Ad5 in its cytolytic effect in porcine cell lines. These in vitro results prompted evaluation of the vectors in vivo. Immunocompetent Yorkshire pigs were systemically injected with a single dose of Ad5- and Ad5/3- expressing luciferase (Luc) from the Ad E3 region. Quantitative PCR analyses of the primary organs collected 7 days post-infection revealed Ad5 and Ad5/3 viral DNA in the lungs and spleen. Replication-dependent Luc expression was also observed in these tissue samples suggesting active viral replication. The quantity of viral DNA in other tissue such as the kidneys, liver, and pancreas was negligible. The results of these in vitro and in vivo studies indicate that pigs are a promising model to assess unmodified and tropism-modified adenoviral vectors.

Citation Format: Malavika Chandrashekar, Lisa Koodie, Michele Dunning, George Ruth, Richard Bianco, Masato Yamamoto, Julia Davydova. The porcine model for onocolytic adenovirus-based therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5914.

Abstract 5925: A novel oncolytic adenovirus for radioiodine therapy and imaging

Recently, the use of oncolytic viruses encoding the sodium-iodide symporter (NIS) has become an attractive approach to achieve radionuclide imaging of cancer. However, the potential of virus-induced NIS expression to facilitate therapy with radioactive 131I has not been fully explored. We designed a tumor-selective, infectivity-improved oncolytic adenovirus (Ad5/3-Cox2-NIS-ADP) modified to express high quantities of NIS. This virus induced radioisotope uptake in prostate and lung cancer cells and facilitated SPECT/CT imaging, but more importantly, supported the effective therapy with 131I. In our original vector, enhanced oncolysis was mediated by overexpression of adenoviral death protein (ADP). Although this structure was operative in detection and therapeutic regimens, we were concerned that the cytolytic effect of ADP may affect NIS membrane localization, and diminish its effectiveness as a theranostic tool. We therefore designed an identical Ad5/3-Cox2-NIS-ADP-deleted virus {ADP(-)} and assessed the impact of ADP on NIS expression and radioisotope uptake. Western blot and immunocytochemical analyses of pancreatic cancer cells infected with ADP(-) demonstrated higher NIS levels when compared to the ADP(+) counterpart. This correlated with an improved 125I uptake in vitro. SPECT/CT imaging studies assessing 99mTcO4- accumulation in mice to visualize pancreatic adenocarcinoma (PDAC) using patient-derived xenografts (PDX) showed that a single dose of ADP(-) accumulated far greater levels of 99mTcO4- when compared to ADP(+). Remarkably, ADP(-) produced stronger signal that was maintained up until day 32, and this outlasted ADP(+) and the control vector, replication-deficient AdCMV-NIS, currently employed in a clinical trial. Notably, within the PDAC, ADP(-) showed a distinct NIS cell membrane distribution pattern as it co-localized with cell membrane bound-cytokeratin-4. Unlike ADP(-), ADP(+) produced a punctate NIS staining pattern, with little to no cell membrane localization. These results support our hypothesis that ADP-cytolytic effect reduces NIS membrane localization, subsequently affecting radionuclide uptake. To evaluate the therapeutic potential of NIS-based radiotherapy, we treated mice bearing PDAC tumors with virotherapy alone or in combination with 131I. NIS-expressing OAds in combination with 131I significantly reduced tumor growth when compared to viro- or radiotherapy alone. The therapeutic effect in mice treated with ADP(-) combined with 131I outperformed that with ADP(+) or AdCMV-NIS vectors. Quantitative analyses of 131I uptake in tumor tissues with a gamma counter showed a clear trend where ADP(-) retained higher 131I uptake than ADP(+). These findings support the clinical applicability of the ADP-deleted OAd as the more sensitive tool for NIS-based cancer diagnosis and therapy. We are currently investigating the biodistributon and toxicity of our vectors in a pig model.

Citation Format: Lisa Koodie, Eriko Iguchi Kawakami, Kari Jacobsen, Zuzan Cayci, Andrew Taylor, Edward W. Greeno, Robert J. Schumacher, John C. Morris, Martin E. Fernandez-Zapico, Julia Davydova. A novel oncolytic adenovirus for radioiodine therapy and imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5925.

Combination of interferon-expressing oncolytic adenovirus with chemotherapy and radiation is highly synergistic in hamster model of pancreatic cancer

Recent clinical trials utilizing Interferon-alpha (IFN) in combination with chemoradiation have demonstrated significant improvements in the survival of patients with pancreatic cancer. However, efficacy was limited by the systemic toxicity of IFN and low intratumoral levels of the cytokine. We sought to address these drawbacks by using an Oncolytic Adenovirus expressing IFN (OAd-hamIFN) in combination with chemotherapy and/or radiation in regimens mimicking the IFN-based therapies used in clinical trials. IFN expressed from OAd-hamIFN potentiated the cytotoxicity of radiation and chemotherapy (5-FU, Gemcitabine, and Cisplatin), and enhanced pancreatic cancer cell death in both in vitro and in vivo experimental settings. Notably, synergism was demonstrated in therapeutic groups that combined the interferon-expressing oncolytic virus with chemotherapy and radiation. In an in vivo immunocompetent hamster model, treatment regimens combining oncolytic virus therapy with 5-FU and radiation demonstrated significant tumor growth inhibition and enhanced survival. This is the first study to report synergism between an IFN-expressing oncolytic adenovirus and chemoradiation-based therapies. When combined with an IFN-expressing OAd, there is a significant enhancement of radiation and especially chemoradiation, which may broaden the application of this new therapeutic approach to the pancreatic cancer patients who cannot tolerate existing chemotherapy regimens.

CD133-targeted oncolytic adenovirus demonstrates anti-tumor effect in colorectal cancer

Oncolytic Adenoviruses (OAds) are one of the most promising anti-cancer agents that can induce cancer specific cell death. Recently, we generated infectivity-selective OAd, and the resultant OAd tumor-specific binding shows strong efficacy and mitigates toxicity. In this study, we applied this strategy based on adenovirus library screening system for generation of CD133-targeted OAd, and examined their oncolytic activity against colorectal cancer (CRC) in vitro and in vivo. CD133 (Prominin-1) is an important cell surface marker of cancer stem (like) cells (CSCs) in various cancers, including CRC. Elimination of CSCs has a high likelihood to improve CRC treatment because CSCs population in the tumor contributes to recurrence, metastases, chemotherapy resistance, and poor survival. The OAd with CD133-targeting motif (AdML-TYML) selectively infected CD133⁺ cultured cells and lysed them efficiently. Treatment with AdML-TYML prior to tumor inoculation inhibited the establishment of tumor of CD133⁺ CRC cell lines in nude mice. AdML-TYML also showed strong antitumor effect after intratumoral injections in already established CD133⁺ CRC subcutaneous xenografts. Our results indicate that CD133-targeted OAd selectively infected CD133⁺ CRC, and exhibited anti-tumorigenicity and therapeutic effect in established tumors. This novel infectivity selective virus could be a potent tool for the prevention of metastases and relapses in CRC.

CD133-targeted oncolytic adenovirus demonstrates anti-tumor effect in colorectal cancer

Oncolytic Adenoviruses (OAds) are one of the most promising anti-cancer agents that can induce cancer specific cell death. Recently, we generated infectivity-selective OAd, and the resultant OAd tumor-specific binding shows strong efficacy and mitigates toxicity. In this study, we applied this strategy based on adenovirus library screening system for generation of CD133-targeted OAd, and examined their oncolytic activity against colorectal cancer (CRC) in vitro and in vivo. CD133 (Prominin-1) is an important cell surface marker of cancer stem (like) cells (CSCs) in various cancers, including CRC. Elimination of CSCs has a high likelihood to improve CRC treatment because CSCs population in the tumor contributes to recurrence, metastases, chemotherapy resistance, and poor survival. The OAd with CD133-targeting motif (AdML-TYML) selectively infected CD133⁺ cultured cells and lysed them efficiently. Treatment with AdML-TYML prior to tumor inoculation inhibited the establishment of tumor of CD133⁺ CRC cell lines in nude mice. AdML-TYML also showed strong antitumor effect after intratumoral injections in already established CD133⁺ CRC subcutaneous xenografts. Our results indicate that CD133-targeted OAd selectively infected CD133⁺ CRC, and exhibited anti-tumorigenicity and therapeutic effect in established tumors. This novel infectivity selective virus could be a potent tool for the prevention of metastases and relapses in CRC.

Abstract 3749: Interaction of 5FU chemotherapy and oncolytic adenovirus in combined cancer treatment

Previous studies have shown that Interferon(IFN)-based chemoradiation therapy can improve survival after resection of pancreas cancer. However, its clinical utility to this point has been limited due to the severe toxicity related to its use of systemic IFN. Our aim in this study is to evaluate our group's novel oncolytic adenovirus (OAd) which allows targeting IFN treatment to cancer cells while sparing healthy tissue. We have previously shown the ability of IFN to sensitize cancer cells to chemotherapy as well as demonstrated an increased therapeutic effect of the drug in immunocompetent models. This study was conducted to analyze the combination of 5FU chemotherapy and our OAd in vitro in order to assess the interaction of treatments and determine the optimum combined treatment regimen.

Treatments were analyzed in pancreatic cancer and esophageal adenocarcinoma cell lines S2013 and OE19. Recombinant OAds expressing luciferase rather than IFN were used to isolate the combination of 5FU and the virus. Two viral models were evaluated: our therapeutic virus (Cox2) selectively replicative in Cox2 expressing cancer cells and a nearly identical but universally replicative virus (wild type). Cells were treated with 0, 1 or 10 viral particles per cell and 0, 5, 10, or 20 uM 5FU. Three timing regimens were used: simultaneous administration, 5FU 4 hours before virus, and virus 48 hours before 5FU. Crystal Violet and MTS Assays were used to measure cell death. Viral Copy number to assess viral replication was measured using qPCR.

Cell death analysis showed time dependent killing of each virus, with a 2 day delay for the Cox2 virus. 5FU and each virus produced dose dependent cell death independently. There was a significant additive effect seen in cell death from combining treatments when using 5FU before virus in both S2013 and OE19. Simultaneous treatment showed an additive killing effect with the combination in S2013, but a reduced killing by the combination compared to virus alone in OE19. There was also reduced killing when using virus before 5FU in S2013. Viral copy experiments are in progress.

Our Cox2 OAd shows a killing effect similar to wild type in multiple cancer cell lines. When combined with 5FU treatment the expected addition in overall cell death from the independent treatments varies by timing of administrations as well as by type of cancer cell line. The reduced killing of the combination treatment in the simultaneous and virus before 5FU regimens may suggest an inhibition of the virus by 5FU under certain conditions. This also suggests the possibility of a treatment regimen with optimal therapeutic effect, which appears to be 5FU before virus based on the results collected. Further studies investigating different chemotherapeutic drugs and regimens should be conducted to examine these trends.

Citation Format: Jordan Sell, Amanda Oliviera, Eric Jensen, Masato Yamamoto, Julia Davydova. Interaction of 5FU chemotherapy and oncolytic adenovirus in combined cancer treatment. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3749.

The Function of Twisted Gastrulation in Regulating Osteoclast Differentiation is Dependent on BMP Binding

Proper regulation of osteoclast (OCL) function is critical for normal bone homeostasis. Bone morphogenetic protein (BMP) signaling and its regulation have been shown to have direct effects on OCL differentiation and activity. One of the major modulators of BMP signaling in the extracellular space is the secreted protein twisted gastrulation (TWSG1), which can inhibit BMP signaling and OCL differentiation. In this study we examine specific N-terminal regions of TWSG1 protein that have been previously proposed as BMP binding sites to determine whether TWSG1 binding to BMPs is required for its inhibitory effects on OCLs. We demonstrate that overexpression of wild type TWSG1 suppresses osteoclastogenesis, while overexpression of mutant TWSG1 proteins (W66A and N80Q/N146Q mutants), which cannot bind BMPs, leads to increased BMP signaling, enhanced osteoclastogenesis, increased resorptive activity, and expression of OCL-specific genes. Our results show that BMP binding is required for TWSG1-mediated inhibition of OCL formation and function, and validate the critical functional regions within the TWSG1 protein for these interactions.

Oncolytic adenoviruses targeted to Human Papilloma Virus-positive head and neck squamous cell carcinomas

OBJECTIVES

In recent years, the incidence of Human Papilloma Virus (HPV)-positive head and neck squamous cell carcinomas (HNSCC) has markedly increased. Our aim was to design a novel therapeutic agent through the use of conditionally replicative adenoviruses (CRAds) that are targeted to the HPV E6 and E7 oncoproteins.

METHODS

Each adenovirus included small deletion(s) in the E1a region of the genome (Δ24 or CB016) intended to allow for selective replication in HPV-positive cells. In vitro assays were performed to analyze the transduction efficiency of the vectors and the cell viability following viral infection. Then, the UPCI SCC090 cell line (HPV-positive) was used to establish subcutaneous tumors in the flanks of nude mice. The tumors were then treated with either one dose of the virus or four doses (injected every fourth day).

RESULTS

The transduction analysis with luciferase-expressing viruses demonstrated that the 5/3 fiber modification maximized virus infectivity. In vitro, both viruses (5/3Δ24 and 5/3CB016) demonstrated profound oncolytic effects. The 5/3CB016 virus was more selective for HPV-positive HNSCC cells, whereas the 5/3Δ24 virus killed HNSCC cells regardless of HPV status. In vivo, single injections of both viruses demonstrated anti-tumor effects for only a few days following viral inoculation. However, after four viral injections, there was statistically significant reductions in tumor growth when compared to the control group (p<0.05).

CONCLUSION

CRAds targeted to HPV-positive HNSCCs demonstrated excellent in vitro and in vivo therapeutic effects, and they have the potential to be clinically translated as a novel treatment modality for this emerging disease.

Smad1/5 and Smad4 expression are important for osteoclast differentiation

To investigate the necessity of the canonical BMP pathway during osteoclast differentiation, we created osteoclasts with a conditional gene deletion for Smad1 and Smad5 (SMAD1/5), or Smad4 using adenovirus expressing CRE recombinase (Ad-CRE). Reduction of either Smad4 or Smad1/5 expression resulted in fewer and smaller multinuclear cells compared to control cells. We also detected changes in osteoclast enriched genes, demonstrated by decreased Dc-stamp and cathepsin K expression in both Smad4 and Smad1/5 Ad-CRE osteoclasts, and changes in c-fos and Nfatc1 expression in only Smad4 Ad-CRE cells. Lastly we also detected a significant decrease in resorption pits and area resorbed in both the Smad4 and Smad1/5 Ad-CRE osteoclasts. Because we inhibited osteoclast differentiation with loss of either Smad4 or Smad1/5 expression, we assessed whether BMPs affected osteoclast activity in addition to BMP's effects on differentiation. Therefore, we treated mature osteoclasts with BMP2 or with dorsomorphin, a chemical inhibitor that selectively suppresses canonical BMP signaling. We demonstrated that BMP2 stimulated resorption in mature osteoclasts whereas treatment with dorsomorphin blocks osteoclast resorption. These results indicate that the BMP canonical signaling pathway is important for osteoclast differentiation and activity.

Imaging and Antitumoral Effect of a Cyclo-oxygenase 2-specific Replicative Adenovirus for Small Metastatic Gastric Cancer Lesions

BACKGROUND

Long-term outcomes of patients with peritoneal dissemination of gastric cancer remain unsatisfactory despite advances in treatment modalities. Internal luminescence conditionally replicative adenovirus (CRAd) presents a novel approach for cancer treatment and imaging.

MATERIALS AND METHODS

3CL is a modified cyclooxygenase-2 (COX2) promoter-driven CRAd which contains the luciferase expression gene for bioluminescence imaging. The visualizing and therapeutic effect of 3CL was evaluated in a mouse model of peritoneal dissemination.

RESULTS

Intraperitoneal injection of 3CL achieved the shrinkage and reduction of lesions of peritoneal dissemination. Six model mice treated with 3CL had a significantly longer mean survival time than 6 mock-treated mice (85.7 versus 34.3 days, p=0.0005). By whole-body bioluminescent imaging, the sensitivity and specificity of peritoneal dissemination detection through macroscopic inspection were 58.1% and 83.2%, respectively, whereas 3CL viral imaging modality yielded corresponding values of 78.8% and 99.3%. Peritoneal lesions detected by imaging histologically contained cancer cells and necrotic tissue, which originated from viral oncolytic effects.

CONCLUSION

Cox2 CRAds with 5/3 chimeric-fiber modification, therefore, appear to be a promising imaging and therapeutic tools for peritoneal dissemination of gastric cancer.

Oncolytic adenovirus expressing interferon alpha in a syngeneic Syrian hamster model for the treatment of pancreatic cancer

BACKGROUND

The addition of interferon (IFN) alpha to adjuvant chemoradiotherapy regimens resulted in remarkable improvements in survival for pancreatic cancer patients. However, systemic toxicities and insufficient levels of IFN at the tumor sites have limited its widespread adoption in treatment schemes. We have previously developed an IFN-expressing conditionally replicative oncolytic adenovirus and demonstrated its therapeutic effects both in vitro and in vivo. Here, the same vectors were tested in a syngeneic and immunocompetent Syrian hamster model to better understand the roles of adenoviral replication and of the pleiotropic effects of IFN on pancreatic tumor growth suppression.

METHODS

Oncolytic adenoviruses expressing human or hamster IFN were designed and generated. Viral vectors were tested in vitro to determine qualitative and quantitative cell viability, cyclooxygenase 2 (Cox2) promoter activity, and IFN production. For the in vivo studies, subcutaneous hamster pancreatic cancer tumors were treated with 1 intratumoral dose of virus. Similarly, 1 intraperitoneal dose of virus was used to prolong survival in a carcinomatosis model.

RESULTS

All cell lines tested demonstrated Cox2 promoter activity. The oncolytic potential of a replication competent adenovirus expressing the IFN cytokine was clearly demonstrated. These viruses resulted in significant tumor growth suppression and survival increases compared with controls in a hamster model.

CONCLUSION

The profound therapeutic potential of an IFN-expressing oncolytic adenovirus for the treatment of pancreatic cancer was demonstrated in a syngeneic Syrian hamster model. These results strongly suggest the potential application of our viruses as part of combination regimens with other therapeutics.

Abstract 724: Systemic injection of fiber-redesigned oncolytic adenovirus eliminates tumors in vivo

Adenovirus (Ad) has been used as a platform of oncolytic viral agents. Unlike loco-regional therapy, systemic application of cancer gene therapy mandates different level of selectivity of gene delivery. Lack of tumor selectivity at the stage of infection has hampered the in vivo efficacy of systemic therapy. The controlled vector distribution and cancer selective transduction would overcome the obstacles for systemic delivery and enable efficient systemic treatment of cancer.

AdML-VTIN was identified as a mesothelin (MSLN) targeted Ad by screening of high-diversity (109-level) Ad fiber mutant library. This AB-loop-redesigned Ad yielded a potent and selective infectivity to MSLN-positive pancreatic cancer (Panc-1) in vitro.

In the examination of in vivo selectivity and anti-tumor effect, the intra-tumor injection of AdML-VTIN showed significant anti-tumor effect against Panc-1 tumors, and about half of the tumor disappeared. Contrarily, the same virus showed no anti-tumor effect in MiaPaCa-2 (MSLN-negative). Viral DNA quantitation supported the selective viral replication only in Panc-1.

We compared organ distribution after intravenous injection to the nude mice with subcutaneous Panc-1 xenograft among AdML-VTIN, AdML-5WT (wild type Ad5 fiber), and AdML-GERS (against PC-3, prostate cancer cell). The liver sequestration of both AB-loop redesigned Ads were more than one order of magnitude lower than that with AdML-5WT at 1hr and 48 hrs after injection. At day 7, the viral copy number of AdML-VTIN in the tumor was more than 3 orders of magnitude higher that those with AdML-5WT.

Next, systemic therapeutic effect was examined with same condition of vector distribution. In only VTIN group, tumor volume was significantly decreased, and about one-third of the tumor was eliminated at 15 days after the injection even though viral amount was pretty low (109vp/mouse).

In this study, systemic injection of the AB-loop redesigned oncolytic Ad with VTIN motif that was identified by Ad library screening showed remarkable anti-tumor effect in spite of low viral amount. This new oncolytic Ad enabling systemic therapy may embody efficient treatment for pancreatic cancers which are mostly found with spread or metastatic lesions.

Citation Format: Yoshiaki Miura, Mizuho Sato, Julia Davydova, Masato Yamamoto. Systemic injection of fiber-redesigned oncolytic adenovirus eliminates tumors in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 724. doi:10.1158/1538-7445.AM2014-724

Oncolytic adenoviruses: design, generation, and experimental procedures

Oncolytic adenoviruses are designed to take advantage of the virus' native ability to replicate in cancer cells to induce oncolysis. Subsequently, the released viral progeny spread and kill the neighboring cancer cells. These characteristics, together with the ability of adenovirus to infect a broad spectrum of cells, its well understood replication machinery, and relative ease of manufacture have led to the intensive use of adenovirus as an anticancer agent. This unit describes cloning strategies, procedures to turn the intended design into virus, and quality analyses of resultant adenoviral vectors. Most of these procedures were optimized especially for oncolytic adenoviral vectors.

Abstract 3308: Systemic administration of fiber redesigned infectivity-selective oncolytic adenovirus for pancreatic cancer

Adenovirus (Ad) has frequently been used as a backbone of oncolytic viral agents, while lack of selectivity to cancer cells at the stage of infection has greatly hampered in vivo efficacy. Unlike loco-regional therapy, systemic application of cancer gene therapy mandates different level of selectivity of gene delivery. The controlled distribution and selective transduction of the vector would overcome the obstacles for systemic delivery and enable efficient systemic treatment of cancer.

We have recently developed transductionally-targeted Ads by high-throughput screening of high-diversity (10ˆ9-level) Ad-library. Mesothelin (MSLN) is highly over-expressed in pancreatic cancers. Ad with redesigned AB-loop targeting MSLN, AdML-VTIN, was successfully isolated from the high throughput screening of Ad library by infectivity for MSLN-expressing 293 cells (293-MSLN).

The in vitro binding of AdML-VTIN corresponded to the level of MSLN-expression and the suppression of MSLN with siRNA or antibody significantly reduced the binding to MSLN-expressing cells, which indicates that mesothelin is a receptor moiety for the isolated targeting ligand. The binding ability of this virus in Panc-1 (MSLN-positive) was higher than that of Ad with 5/3 modified fiber which is known to exhibit highest infectivity in pancreatic cancer cells. The in vivo antitumor effect was compared in Panc-1 and MiaPaCa-2 (MSLN-negative) subcutaneous xenografts. The injection of the MSLN-retargeted oncolytic Ad showed significant antitumor effect against Panc-1 tumors, and about half of the tumor disappeared. Contrarily, the same virus showed no antitumor effect in MiaPaCa-2. Viral DNA quantitation also supported the selective viral replication in Panc-1.

Upon systemic administration in the nude mice with Panc-1 subcutaneous xenografts, the sequestration of AdML-VTIN to the liver was significantly lower than that of wild-type Ad5, and the copy number of this retargeted virus was significantly (1000 fold) higher in the tumor. These data indicates the systemic delivery of this vector is efficient for MSLN-expression pancreatic cancer xenografts.

In this study, our MSLN-targeted Ad vector exhibited significant infectivity to MSLN-positive pancreatic cancer cells in vitro and in vivo. Moreover, this virus showed significantly reduced liver sequestration as well as dramatically augmented delivery to the tumors upon systemic administration. This new genetically modified Ad transductionally retargeted to pancreatic cancer may embody a next generation targeting for this devastating disease in clinical settings.

Citation Format: Yoshiaki Miura, Joohee Han, Julia Davydova, Masato Yamamoto. Systemic administration of fiber redesigned infectivity-selective oncolytic adenovirus for pancreatic cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3308. doi:10.1158/1538-7445.AM2013-3308

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Intravenous genetic mesothelin vaccine based on human adenovirus 40 inhibits growth and metastasis of pancreatic cancer

High pancreatic cancer mortality and poor prognosis are caused by the difficulty for early diagnosis and extremely low rates of resection because of metastasis. Mesothelin overexpression in pancreatic cancer is a remarkable biomarker for tumor progression, especially for invasion and metastasis. Here, we generated a novel replication-defective recombinant adenovirus 40 (rAd40), whose gene delivery properties are totally different from a conventional rAd5. In this study, we have identified intravenous administration with rAd40 expressing mouse mesothelin (Msln) as an effective prophylactic cancer vaccine against metastatic lesions of pancreatic cancer in mice. Intravenous administration of rAd40 (rAd40 i.v.) achieved transgene delivery in wider range of organs compared to rAd5 i.v., while rAd5 was distributed mainly to the liver, spleen, and lungs. Additionally, rAd40 i.v. showed less transduction of the liver or inflammatory responses, resulted in reduced liver toxicity compared to rAd5 i.v. Also, more robust systemic antigen-specific immune responses were stimulated by rAd40 i.v. Pretreatment with a single ovalbumin-expressing rAd40 i.v. prevented tumor growth in mouse subcutaneous models of ovalbumin-expressing pancreatic cancer. When used with Msln-expressing rAd40 i.v., Msln protein expression and metastases were suppressed in a syngeneic orthotopic mouse model of pancreatic cancer, corresponding to the detection of Msln- and tumor-specific cytotoxic T lymphocyte (CTL). Our novel methods generated antitumor effects against antigen-expressing tumors through antigen- and tumor-specific CTL-mediated immunity. Thus, our results indicate that a rAd40-based intravenous vaccine provides a new strategy for the effective control of metastatic pancreatic cancer and novel therapy against other cancers and infectious diseases.

Characterization of infectivity-enhanced conditionally replicating adenovectors for prostate cancer radiovirotherapy

Prostate cancer (PCa) is the second most commonly diagnosed and sixth leading cause of cancer death in American men and one for which no curative therapy exists after metastasis. To meet this need for novel therapies, our laboratory has previously generated conditionally replicating adenovirus (CRAd) vectors expressing the sodium iodide symporter (hNIS). This virus transduced PCa cells and induced functional NIS expression, allowing for noninvasive tumor imaging and combination therapy with radioiodide, referred to as radiovirotherapy. We have now generated two new modified vectors to further improve efficacy. Ad5/3PB-ADP-hNIS and Ad5/3PB-hNIS include a hybrid Ad5/3 fiber knob to improve transduction efficiency, and express NIS from the endogenous major late promoter to restrict NIS expression to target cells. Additionally, Ad5/3PB-ADP-hNIS includes the adenovirus death protein (ADP), which hastens the release of viral particles after assembly. These two vectors specifically induce radioisotope uptake, cytopathic effect, and viral replication in androgen receptor-expressing PCa cell lines with Ad5/3PB-ADP-hNIS showing earlier (131)I uptake and cytolysis at low multiplicity of infection. SPECT-CT imaging of xenograft tumors infected with Ad5/3PB-hNIS showed steady uptake, whereas infection with Ad5/3PB-ADP-hNIS led to increasing uptake, indicating viral spread. Radiovirotherapy of xenograft LNCaP tumors with Ad5/3PB-ADP-hNIS showed the most significant survival extension versus control tumors (p=0.001), but the benefit of radiovirotherapy was not statistically significant compared with virotherapy alone in this model. These results show the potential of Ad5/3PB-ADP-hNIS as a vector for treatment of prostate cancer.

Generation of a novel, cyclooxygenase-2-targeted, interferon-expressing, conditionally replicative adenovirus for pancreatic cancer therapy

BACKGROUND

Oncolytic adenoviruses provide a promising alternative for cancer treatment. Recently, adjuvant interferon (IFN)-alfa has shown significant survival benefits for pancreatic cancer, yet was impeded by systemic toxicity. To circumvent these problems adenovirus with high-level targeted IFN-alfa expression can be generated.

METHODS

Conditionally replicative adenoviruses (CRAds) with improved virulence and selectivity for pancreatic cancer were generated. The vectors were tested in vitro, in vivo, and in human pancreatic cancer and normal tissue specimens.

RESULTS

Adenoviral death protein and fiber modifications significantly improved oncolysis. CRAds selectively replicated in vitro, in vivo and showed persistent spread in cancer xenografts. They showed high-level replication in human pancreatic cancer specimens, but not in normal tissues. Improved IFN-CRAd oncolytic efficiency was shown.

CONCLUSIONS

Optimized cyclooxygenase-2 CRAds show highly favorable effects in vitro and in vivo. We report a pancreatic cancer-specific, highly virulent, IFN-expressing CRAd, and we believe that adenovirus-based IFN therapy offers a new treatment opportunity for pancreatic cancer patients.

Abstract 5655: Infectivity selective oncolytic adenovirus for pancreatic cancer by redesigning the AB-loop via adenovirus library screening

A number of cancers, including pancreatic cancer, are resistant to adenovirus (Ad) infection. Genetically coded viral capsid modification has achieved increased infectivity but not much target specificity. Direct selection of targeted vector from Ad library is a promising approach to overcome this issue. We have established a novel Ad vector generating system enabling a huge-size Ad library. We hypothesize that Ad with redesigned AB-loop isolated by the screening of the new library system would result in a new class of oncolytic adenovirus with selective infectivity for the therapy of pancreatic cancer. Ad AB-loop library was screened with mesothelin-expressing 293 cells (293-MSLN) to target mesothelin (MSLN) which is highly over-expressed in pancreatic cancer, and the clones converged to one dominant clone. The binding of Ad with selected clone was analyzed with 293, Panc-1, MiaPaCa-2, A549 and 293-MSLN. The binding was significantly higher in 293-MSLN than any other cells and corresponded to the order of MSLN-expression by FACS analysis. The anti-MSLN siRNA and antibody significantly reduced the binding to MSLN expressing cells. The binding ability of the virus with this motif in Panc-1 was higher than that of Ad with 5/3 modified fiber which is known to exhibit remarkably enhanced infectivity pancreatic cancer cells. The anti-tumor effect was analyzed in vivo using Panc-1 as a MSLN-positive and MiaPaCa-2 as a MSLN-negative subcutaneous tumors. The injection of the selected clone showed significant anti-tumor effect against Panc-1 tumors, and almost complete regression of some Panc-1 tumors was observed, while it didn't demonstrate anti-tumor effect against MiaPaCa-2 tumors. The hexon immunostaining and the intratumoral viral copy number also indicated that the selected clone replicated in MSLN-positive pancreatic cancer, but not in MSLN-negative cancer. In this study, we selected MSLN targeting Ad vector from the high throughput screening of Ad library by infectivity. The selected clone exhibited significant infectivity to MSLN-positive pancreatic cancer cells in vitro and in vivo. This new genetically modified oncolytic Ad with selective infectivity to pancreatic cancer may embody next generation targeted therapeutics for this devastating disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5655. doi:1538-7445.AM2012-5655

Delivery of interferon alpha using a novel Cox2-controlled adenovirus for pancreatic cancer therapy

BACKGROUND

Combination therapy with interferon alpha (IFN) is correlated with improved survival in patients with pancreatic ductal adenocarcinoma (PDAc) but frequently presents side effects. We designed a novel targeted adenovirus with replication restricted to cyclooxygenase 2 (Cox2)-overexpressing PDAcs and hypothesize that the locally delivered therapeutic gene IFN can augment oncolytic effects while minimizing systemic toxicity.

METHODS

IFN-expressing vectors were tested in vitro with the use of 4 PDAc cell lines with cytocidal effect measured by crystal violet and colorimetrically and IFN production assayed by ELISA. Cox2 promoter activity was checked by a luciferase reporter assay. In vivo, subcutaneous tumor xenografts with 2 PDAc cell lines in nude mice were treated with a single intratumoral viral dose.

RESULTS

All PDAc cell lines were Cox2-positive. Oncolysis from the novel Cox2-controlled virus was comparable or superior to Adwt, the wild-type virus without safety features. The absence of cytocidal effect in Cox2-negative cells with the novel virus indicated cancer specificity. In vivo, stronger tumor suppression from the novel virus was seen when compared with nonreplicating IFN-expressing vectors.

CONCLUSION

We demonstrated the potent therapeutic effects of a novel tumor-specific conditionally replicative IFN-expressing adenovirus. With potential to locally deliver IFN and avoid systemic toxicity, this strategy may therefore expand the application of this robust and promising therapy.

Bone morphogenetic protein 2 signaling in osteoclasts is negatively regulated by the BMP antagonist, twisted gastrulation

Bone morphogenetic proteins (BMPs) have been shown to regulate both osteoblasts and osteoclasts. We previously reported that BMP2 could directly enhance RANKL-mediated osteoclast differentiation by increasing the size and number of osteoclasts. Similarly, genetic deletion of the BMP antagonist Twisted gastrulation (TWSG1) in mice, resulted in an enhancement of osteoclast formation, activity and osteopenia. This was accompanied by increased levels of phosphorylated Smad (pSmad) 1/5/8 in Twsg1(-/-) osteoclasts in vitro. The purpose of this study was to develop an adenoviral vector overexpressing Twsg1 as a means of inhibiting osteoclast activity. We demonstrate that overexpressing TWSG1 in primary osteoclasts decreased the size and number of multinuclear TRAP-positive osteoclasts, expression of osteoclast genes, and resorption ability. Overexpression of TWSG1 did not affect osteoclast proliferation or apoptosis. However, overexpression of TWSG1 decreased the levels of pSmad 1/5/8 in osteoclasts. Addition of exogenous BMP2 to osteoclasts overexpressing TWSG1 rescued the size and levels of pSmad 1/5/8 compared to cultures infected with a control virus. Finally, TWSG1 overexpression in osteoclasts isolated from the Twsg1(-/-) mice rescued size of the osteoclasts while further addition of exogenous BMP2 reversed the effect of TWSG1 overexpression and increased the size of the osteoclasts similar to control virus infected cells. Taken together, we demonstrate that overexpressing TWSG1 in osteoclasts via an adenoviral vector results in inhibition of osteoclastogenesis and may provide a potential therapy for inhibiting osteoclast activity in a localized manner.

Development of a method for effective amplification of human adenovirus 40

Human adenovirus 40 (Ad40) is an interesting candidate for vector construction because of its tropism for the gastrointestinal tract. Although effective preparation of the vector is necessary for its in vivo application, amplification of Ad40 has been very difficult. Ad40 E1 deletion mutants were detected by PCR in the viral DNA from Ad40 Dugan amplified by Ad5 E1-expressing human embryonic kidney (293) cells and in Ad40 Dugan plaques observed with Ad5 E1-expressing human retinoblastic cells. For the purpose of generating a single wild-type Ad40 clone, the entire Ad40 DNA was cloned into a plasmid by homologous recombination. A pure Ad40 was successfully generated by plasmid transfection and subsequently amplified with Ad5 E4orf6-inducible 293 (2V6.11) cells. 2V6.11 is an apposite cell line for effective Ad40 amplification and for future vector construction because Ad40 genetic integrity was maintained with this Ad5 E1 and E4orf6 trans-complementing cell line.

In vivo bioimaging tracks conditionally replicative adenoviral replication and provides an early indication of viral antitumor efficacy

In vivo monitoring of conditionally replicative adenovirus (CRAd) replication and assessing its correlation to CRAd biological effects are necessary for the clinical development of gene therapy. Noninvasive bioimaging is one current approach which can monitor in vivo CRAd replication and functional effect. Here we describe a novel cyclooxygenase-2 (Cox2) promoter-controlled CRAd that was modified to contain firefly luciferase in its E3 region; this modification permitted serial bioluminescence imaging of viral replication in vitro and in vivo. In vitro luciferase expression correlated with viral replication and cytolytic effect. In vivo bioluminescence imaging showed dynamic representation of the viral replication level in athymic nude mice bearing subcutaneous tumor xenografts. Importantly, in vivo luciferase bioluminescence measured 6 days after viral administration significantly correlated with CRAd antitumor effect at day 36. Thus, our system could detect viral replication and predict in vivo therapeutic outcome based on early imaging. Further development of this approach may improve patient safety, enhance clinical trial conduct, and provide mechanistic insight into CRAd function in vivo. (Cancer Sci 2009; 00: 000–000)

Anti-ERBB2 sh-RNA suppress both cell growth and tumor growth in ERBB2-overexpressing upper gastrointestinal adenocarcinomas

INTRODUCTION

ERBB2 is overexpressed in 15-25% of upper gastrointestinal adenocarcinomas. We use a stable lentiviral shRNA model to demonstrate that ERBB2 suppression in upper gastrointestinal adenocarcinomas with documented ERBB2 amplification effectively decreases ERBB2 protein levels and decreases cell viability. Further, we evaluate tumor growth of cells treated with the ERBB2 shRNA.

METHODS

Three upper gastrointestinal adenocarcinoma cells lines with varying ERBB2 levels were treated with one of three separate lentiviral green fluorescent protein (GFP)-labeled ERBB2 shRNA vectors or a nonsilencing control shRNA vector for 6 h. Protein levels on day 6 and cell viability was evaluated on days 3-10. A xenograft in vivo experiment was performed using OE19 cells pretransduced with ERBB2 shRNA to evaluate tumor growth.

RESULTS

ERBB2 protein levels decreased by 80%. ERBB2 knockdown significantly decreased cell viability in cell lines with high ERBB2 levels. In vivo tumor growth was suppressed in ERBB2-shRNA-treated groups.

CONCLUSION

ERBB2 suppression based on a stable lentiviral shRNA transfection system effectively decreases cell viability in cell lines with amplification of ERBB2 as compared to cell lines without overexpression. ERBB2 knockdown significantly decreases tumor growth in vivo. ERBB2-directed therapy may be of benefit in the subset of patients with gastrointestinal adenocarcinomas exhibiting overamplification of ERBB2.

ERBB2 suppression decreases cell growth via apoptosis in gastrointestinal adenocarcinomas

BACKGROUND

Although the incidence of adenocarcinoma of the esophageal and gastroesophageal junction has increased at an alarming rate in the past 30 years, little improvement has been made in treatment strategies. Previous studies have demonstrated that many upper gastrointestinal (GI) adenocarcinomas exhibit ERBB2 amplification. In cancers proven to have similar amplification, such as breast, ERBB2-targeted therapies have dramatically improved overall survival and disease-free rates of survival. This study uses siRNA to knockdown ERBB2 in GI adenocarcinoma cell lines to evaluate cell viability, apoptosis, and changes in cell cycle.

METHODS

A cell line with a baseline amount of ERBB2 (Seg-1) and 2 upper GI adenocarcinoma cell lines with known amplification of ERBB2 (esophageal [OE19] and gastric [MKN45]) were treated with 120 pmol of 1 of 2 independent ERBB2 siRNAs or control siRNA for 6 hours.

RESULTS

We demonstrate that knockdown of ERBB2 in esophageal and gastric cancer cell lines with known ERBB2 amplification effectively decreases ERBB2 protein levels and decreases cell viability mainly via apoptotic pathways.

CONCLUSION

ERBB-directed therapy may be of benefit in the subset of patients with GI adenocarcinomas exhibiting amplification of ERBB2.

Construction of an MUC-1 promoter driven, conditionally replicating adenovirus that expresses the sodium iodide symporter for gene therapy of breast cancer

Introduction

The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. This in turn allows radioiodine imaging and therapy for thyroid cancer. To extend the use of NIS-mediated radioiodine therapy to other types of cancer, we successfully transferred and expressed the sodium-iodide symporter (NIS) gene in prostate, colon, and breast cancer cells both in vivo and in vitro by using non-replicating adenoviral vectors.

Methods

To improve virotherapy efficiency, we developed a conditionally replicating adenovirus (CRAd) in which the transcriptional cassette RSV promoter-human NIScDNA-bGH polyA was also inserted at the E3 region. The E1a gene is driven by the tumor-specific promoter MUC-1 in the CRAd Ad5AMUCH_RSV-NIS.

Results

In vitro infection of the MUC-1-positive breast cell line T47D resulted in virus replication, cytolysis, and release of infective viral particles. Conversely, the MUC-1-negative breast cancer cell line MDA-MB-231 was refractory to the viral cytopathic effect and did not support viral replication. The data indicate that Ad5AMUCH_RSV-NIS activity is stringently restricted to MUC-1-positive cancer cells. Radioiodine uptake was readily measurable in T47 cells infected with Ad5AMUCH_RSV-NIS 24 hours after infection, thus confirming NIS expression before viral-induced cell death.

Conclusions

This construct may allow multimodal therapy, combining virotherapy with radioiodine therapy to be developed as a novel treatment for breast and other MUC1-overexpressing cancers.

Combination of conditionally replicative adenovirus and standard chemotherapies shows synergistic antitumor effect in pancreatic cancer

Due to devastating prognosis, novel therapies are needed for pancreatic cancer. We are in preparation for a human clinical trial of a conditionally replicative adenovirus (CRAd) we developed. While most patients in the target population are receiving either gemcitabine or 5-fluorouracil chemotherapy, the combination with CRAd has not yet been studied. This study was designed to evaluate combination therapies with CRAd and current standard chemotherapies in pancreatic cancer. When the combination therapy was tested in vitro, gemcitabine pretreatment showed a synergistic effect in two out of four cell lines whereas CRAd followed by gemcitabine exhibited a synergistic effect in one cell line. With 5-fluorouracil, pretreatment with 5-fluorouracil produced a synergistic effect in three cell lines whereas post-treatment was synergistic in only one cell line. These effects were not fully explained by either induction of cyclooxygenase (Cox) 2 activity or adenoviral receptors with chemotherapeutics. In in vivo analyses with Hs766T xenograft, 5-fluorouracil slightly improved the CRAd antitumor effect but it was not significant. Pretreatment with gemcitabine embodied a significant tumor reduction compared with single therapy with gemcitabine. The most significant antitumor effect occurred when tumors were treated with 5/3COX2CRAdF and subsequent gemcitabine (P = 0.001 vs gemcitabine alone, P = 0.012 vs 5/3COX2CRAdF alone) at day 12. In MIA Paca-2, pretreatments with either 5-fluorouracil or gemcitabine improved the CRAd therapeutic effect when administered before CRAd injection (P = 0.03 and P = 0.01, respectively). These experiments indicate the possible benefit of combination therapies, and thus it is not necessary to interrupt chemotherapeutics when receiving CRAd therapy.

A novel adenovirus expressing Flt3 ligand enhances mucosal immunity by inducing mature nasopharyngeal-associated lymphoreticular tissue dendritic cell migration

Previously, we showed that nasal administration of a naked cDNA plasmid expressing Flt3 ligand (FL) cDNA (pFL) enhanced CD4(+) Th2-type, cytokine-mediated mucosal immunity and increased lymphoid-type dendritic cell (DC) numbers. In this study, we investigated whether targeting nasopharyngeal-associated lymphoreticular tissue (NALT) DCs by a different delivery mode of FL, i.e., an adenovirus (Ad) serotype 5 vector expressing FL (Ad-FL), would provide Ag-specific humoral and cell-mediated mucosal immunity. Nasal immunization of mice with OVA plus Ad-FL as mucosal adjuvant elicited high levels of OVA-specific Ab responses in external secretions and plasma as well as significant levels of OVA-specific CD4(+) T cell proliferative responses and OVA-induced IFN-gamma and IL-4 production in NALT, cervical lymph nodes, and spleen. We also observed higher levels of OVA-specific CTL responses in the spleen and cervical lymph nodes of mice given nasal OVA plus Ad-FL than in mice receiving OVA plus control Ad. Notably, the number of CD11b(+)CD11c(+) DCs expressing high levels of costimulatory molecules was preferentially increased. These DCs migrated from the NALT to mucosal effector lymphoid tissues. Taken together, these results suggest that the use of Ad-FL as a nasal adjuvant preferentially induces mature-type NALT CD11b(+)CD11c(+) DCs that migrate to effector sites for subsequent CD4(+) Th1- and Th2-type cytokine-mediated, Ag-specific Ab and CTL responses.

NALT CD11b+ Dendritic Cell Migration Contributes to Induction of Ag Specific Immunity (B111)

Our previous study showed that targeting nasopharyngeal-associated lymphoreticular tissue (NALT) dendritic cells (DCs) with an adenovirus vector expressing Flt3 Ligand (Ad-FL) induced Ag-specific mucosal immunity that mediated by increased numbers of DCs and CD4+ Th1- and Th2-type cytokine responses. In this study, we examined the kinetics of DC subset formation and intracellular cytokine production in NALT and in cervical lymph nodes (CLNs). C57BL/6 mice were nasally immunized with Ad-FL and OVA three times at weekly intervals. As controls, mice were given Ad expressing the firefly luciferase protein (Ad-Luc). Mononuclear cells were isolated at various time points and the frequencies of DC subsets and intracellular cytokine production by CD4+ T cells were determined by FACS. An Increased frequency in CD11b+ DCs was seen in nasal passages (NPs) and submundibular glands (SMGs) at day 21. On the other hand, the frequency as well as the actual numbers of DCs in NALT was the highest 3 days after the second nasal immunization. Further, peak cell numbers of CD11b+ DCs in CLNs were seen at day 14. Of importance, intracellular cytokine FACS analysis showed highest IFN- γ and IL-4 production in CLNs at day14.

These results suggest that NALT CD11b+ DCs migrate into NPs and SMGs via the CLN and play an important role in the induction of both Th1- and Th2-type cytokine responses in mice given Ad-FL as nassal adjuvant.

Supported by DE 12242, AI 18958, AI 43197, and AG 025873.

Suppressor of cytokine signaling-1 expression by infectivity-enhanced adenoviral vector inhibits IL-6-dependent proliferation of multiple myeloma cells

Multiple myeloma (MM) accounts for 10% of hematological malignant disorders. Its refractory nature indicates the necessity of developing novel therapeutic modalities. Since interleukin 6 (IL-6) is one of the major growth factors for MM cells, we expressed suppressor of cytokine signaling-1 (SOCS-1), one of the blockades of IL-6 receptor downstream signaling, to suppress the proliferation of MM cells. Because MM cells are resistant to conventional adenoviral vector infection, we utilized infectivity-enhanced adenoviral vectors with an RGD4C motif in the adenoviral fiber-knob region (RGD-modified vector). In infectivity analysis, RGD-modified vectors were superior to unmodified controls in the majority of the MM cell lines tested. The overexpression of SOCS-1 using infectivity-enhanced adenoviral vectors achieved growth suppression in IL-6-dependent MM cells, but not in the IL-6-independent cells. IL-6-induced STAT3 phosphorylation was suppressed in IL-6-dependent cells, indicating that the signal transduction cascade of the IL-6 receptor signaling was blocked. In aggregate, SOCS-1 overexpression with RGD-modified adenoviral vectors achieved the antiproliferative effect in IL-6-dependent MM cells. These results provide an initial proof-of-principle of the anticancer effect of SOCS-1 expression vector as well as a promise for the future development of therapeutic modality for MM based on this vector.

Oncolytic adenoviral therapy in gallbladder carcinoma

BACKGROUND

Oncolytic adenoviral therapy is a promising new approach for cancer treatment. The aim of this study was to improve the conditionally replicative adenoviruses (CRAds) for gallbladder cancer therapy by modifying the fiber-knob region for infectivity enhancement and by incorporating tumor-specific promoters (TSPs) for enhanced specificity.

METHODS

For promoter-controlled replication, in vitro efficacy of eight TSPs was investigated in two gallbladder cancer cell lines (NOZ and OCUG-1). Infectivity enhancement was analyzed by two different fiber modifications: Arg-Gly-Asp (RGD) incorporation into the HI loop (RGD modification) and a chimeric construct with a serotype 5 shaft and a serotype 3 knob (5/3 fiber modification). Comparisons were made by infectivity analysis and cytotoxicity assays in vitro, followed by tumor suppressive effects tested in vivo.

RESULTS

Among TSPs, highest potency was exhibited by the cyclooxygenase-2 (COX-2), Midkine, and vascular endothelial growth factor promoters in both cell lines tested. Fiber chimera (Ad5/3Luc1) conferred significant enhancement of Ad infectivity in comparison with unmodified and RGD-modified vectors. COX-2 CRAds demonstrated selective cytocidal effect in gallbladder cancer cells in vitro. COX-2 promoter-based Ad5/3 CRAds showed significantly enhanced tumor-suppressive effect compared with nonreplicative and RGD-modified CRAd vectors in vivo.

CONCLUSIONS

The 5/3 fiber-modified, COX-2 promoter-driven CRAds may prove to be a new agent for the treatment of gallbladder carcinoma.

Combining high selectivity of replication with fiber chimerism for effective adenoviral oncolysis of CAR-negative melanoma cells

Oncolytic adenoviruses constitute a new and promising tool for cancer treatment that has been rapidly translated into clinical trials. However, minimal or absent expression of the adenovirus serotype 5 (Ad5) receptor CAR (coxsackievirus and adenovirus receptor) on cancer cells represents a major limitation for Ad5-based oncolysis. Here, we report on the resistance of CAR-negative primary melanoma cells to cell killing by wild-type Ad5 (Ad5wt) even after high titer infection, thus underlining the need for tropism-modification of oncolytic adenoviruses. We engineered a new generation of oncolytic adenoviruses that exhibit both efficient target cell infection by swapping Ad5 fiber domains with those of Ad serotype 3, which binds to a receptor distinct from CAR, and targeted virus replication. Fiber chimerism resulted in efficient cytopathicity to primary melanoma cells, which was at least 10(4)-fold increased relative to Ad5wt. Since viral infectivity mediated by such modified viral capsids was not cell type-specific, it was pivotal to carefully restrict adenoviral replication to target cells. Towards this end, we replaced both E1A and E4 promoters of fiber chimeric viruses by tyrosinase enhancer/promoter constructs. The resulting viruses showed melanoma-specific expression of E1A and E4 and combined efficient virus replication and cell killing in melanoma cell lines and primary melanoma cells with a remarkable specificity profile that implements strong attenuation in nonmelanoma cells, including normal fibroblasts and keratinocytes.