Overexpression of Adenovirus E1A Reverses Transforming Growth Factor-ß-induced Epithelial-mesenchymal Transition in Human Esophageal Cancer Cells.

The epithelial-mesenchymal transition (EMT), a normal biological process by which epithelial cells acquire a mesenchymal phenotype, is associated with migration, metastasis, and chemoresistance in cancer cells, and with poor prognosis in patients with esophageal cancer. However, therapeutic strategies to inhibit EMT in tumor environments remain elusive. Here, we show the therapeutic potential of telomerase-specific replication- competent oncolytic adenovirus OBP-301 in human esophageal cancer TE4 and TE6 cells with an EMT phenotype. Transforming growth factor-ß (TGF-ß) administration induced the EMT phenotype with spindleshaped morphology, upregulation of mesenchymal markers and EMT transcription factors, migration, and chemoresistance in TE4 and TE6 cells. OBP-301 significantly inhibited the EMT phenotype via E1 accumulation. EMT cancer cells were susceptible to OBP-301 via massive autophagy induction. OBP-301 suppressed tumor growth and lymph node metastasis of TE4 cells co-inoculated with TGF-ß-secreting fibroblasts. Our results suggest that OBP-301 inhibits the TGF-ß-induced EMT phenotype in human esophageal cancer cells. OBP-301-mediated E1A overexpression is a promising antitumor strategy to inhibit EMT-mediated esophageal cancer progression.

Integrated fluorescent cytology with nano-biologics in peritoneally disseminated gastric cancer.

Gastric cancer patients positive for peritoneal cytology are at increased risk of tumor recurrence, but although a certain proportion of cytology-positive patients relapse rapidly with aggressive progression, others survive longer with conventional chemotherapies. This heterogeneity makes it difficult to stratify patients for more intensive therapy and poses a substantial challenge for the implementation of precision medicine. We developed a new approach to identify biologically malignant subpopulations in cytology-positive gastric cancer patients, using a green fluorescent protein (GFP)-expressing attenuated adenovirus in which the telomerase promoter regulates viral replication (TelomeScan, OBP-401). The fluorescence emitted from TelomeScan-positive cells was successfully quantified using a multi-mode microplate reader. We then analyzed clinical peritoneal washes obtained from 68 gastric cancer patients and found that patients positive for TelomeScan had a significantly worse prognosis. In 21 cytology-positive patients, the median survival time of those who were TelomeScan positive (235 days) was significantly shorter than that for those who were TelomeScan negative (671 days; P = 0.0062). This fluorescent virus-guided cytology detects biologically malignant cancer cells from the peritoneal washes of gastric cancer patients and may thus be useful for both therapy stratification and precision medicine approaches based on genetic profiling of disseminated cells.

Rethinking medulloblastoma from a targeted therapeutics perspective.

INTRODUCTION: Medulloblastoma is an aggressive but potentially curable central nervous system tumor that remains a treatment challenge. Analysis of therapeutic targets can provide opportunities for the selection of agents. METHODS: Using multiplatform analysis, 36 medulloblastomas were extensively profiled from 2009 to 2015. Immunohistochemistry, next generation sequencing, chromogenic in situ hybridization, and fluorescence in situ hybridization were used to identify overexpressed proteins, immune checkpoint expression, mutations, tumor mutational load, and gene amplifications. RESULTS: High expression of MRP1 (89%, 8/9 tumors), TUBB3 (86%, 18/21 tumors), PTEN (85%, 28/33 tumors), TOP2A (84%, 26/31 tumors), thymidylate synthase (TS; 80%, 24/30 tumors), RRM1 (71%, 15/21 tumors), and TOP1 (63%, 19/30 tumors) were found in medulloblastoma. TOP1 was found to be enriched in metastatic tumors (90%; 9/10) relative to posterior fossa cases (50%; 10/20) (p = 0.0485, Fisher exact test), and there was a positive correlation between TOP2A and TOP1 expression (p = 0.0472). PD-1 + T cell tumor infiltration was rare, PD-L1 tumor expression was uncommon, and TML was low, indicating that immune checkpoint inhibitors as a monotherapy should not necessarily be prioritized for therapeutic consideration based on biomarker expression. Gene amplifications such as those of Her2 or EGFR were not found. Several unique mutations were identified, but their rarity indicates large-scale screening efforts would be necessary to identify sufficient patients for clinical trial inclusion. CONCLUSIONS: Therapeutics are available for several of the frequently expressed targets, providing a justification for their consideration in the setting of medulloblastoma.

Multiplatform profiling of meningioma provides molecular insight and prioritization of drug targets for rational clinical trial design.

INTRODUCTION: Surgery and radiation therapy are the standard treatment options for meningiomas, but these treatments are not always feasible. Expression profiling was performed to determine the presence of therapeutic actionable biomarkers for prioritization and selection of agents. METHODS: Meningiomas (n = 115) were profiled using a variety of strategies including next-generation sequencing (592-gene panel: n = 14; 47-gene panel: n = 94), immunohistochemistry (n = 8-110), and fluorescent and chromogenic in situ hybridization (n = 5-70) to determine mutational and expression status. RESULTS: The median age of patients in the cohort was 60 years, with a range spanning 6-90 years; 52% were female. The most frequently expressed protein markers were EGFR (93%; n = 44), followed by PTEN (77%; n = 110), BCRP (75%; n = 8), MRP1 (65%, n = 23), PGP (62%; n = 84), and MGMT (55%; n = 97). The most frequent mutation among all meningioma grades occurred in the NF2 gene at 85% (11/13). Recurring mutations in SMO and AKT1 were also occasionally detected. PD-L1 was expressed in 25% of grade III cases (2/8) but not in grade I or II tumors. PD-1 + T cells were present in 46% (24/52) of meningiomas. TOP2A and thymidylate synthase expression increased with grade (I = 5%, II = 22%, III = 62% and I = 5%, II = 23%, III = 47%, respectively), whereas progesterone receptor expression decreased with grade (I = 79%, II = 41%, III = 29%). CONCLUSION: If predicated on tumor expression, our data suggest that therapeutics directed toward NF2 and TOP2A could be considered for most meningioma patients.

Biological ablation of sentinel lymph node metastasis in submucosally invaded early gastrointestinal cancer.

Currently, early gastrointestinal cancers are treated endoscopically, as long as there are no lymph node metastases. However, once a gastrointestinal cancer invades the submucosal layer, the lymph node metastatic rate rises to higher than 10%. Therefore, surgery is still the gold standard to remove regional lymph nodes containing possible metastases. Here, to avoid prophylactic surgery, we propose a less-invasive biological ablation of lymph node metastasis in submucosally invaded gastrointestinal cancer patients. We have established an orthotopic early rectal cancer xenograft model with spontaneous lymph node metastasis by implantation of green fluorescent protein (GFP)-labeled human colon cancer cells into the submucosal layer of the murine rectum. A solution containing telomerase-specific oncolytic adenovirus was injected into the peritumoral submucosal space, followed by excision of the primary rectal tumors mimicking the endoscopic submucosal dissection (ESD) technique. Seven days after treatment, GFP signals had completely disappeared indicating that sentinel lymph node metastasis was selectively eradicated. Moreover, biologically treated mice were confirmed to be relapse-free even 4 weeks after treatment. These results indicate that virus-mediated biological ablation selectively targets lymph node metastasis and provides a potential alternative to surgery for submucosal invasive gastrointestinal cancer patients.

Fluorescence virus-guided capturing system of human colorectal circulating tumour cells for non-invasive companion diagnostics.

BACKGROUND: Molecular-based companion diagnostic tests are being used with increasing frequency to predict their clinical response to various drugs, particularly for molecularly targeted drugs. However, invasive procedures are typically required to obtain tissues for this analysis. Circulating tumour cells (CTCs) are novel biomarkers that can be used for the prediction of disease progression and are also important surrogate sources of cancer cells. Because current CTC detection strategies mainly depend on epithelial cell-surface markers, the presence of heterogeneous populations of CTCs with epithelial and/or mesenchymal characteristics may pose obstacles to the detection of CTCs. METHODS: We developed a new approach to capture live CTCs among millions of peripheral blood leukocytes using a green fluorescent protein (GFP)-expressing attenuated adenovirus, in which the telomerase promoter regulates viral replication (OBP-401, TelomeScan). RESULTS: Our biological capturing system can image epithelial and mesenchymal tumour cells with telomerase activities as GFP-positive cells. After sorting, direct sequencing or mutation-specific PCR can precisely detect different mutations in KRAS, BRAF and KIT genes in epithelial, mesenchymal or epithelial-mesenchymal transition-induced CTCs, and in clinical blood samples from patients with colorectal cancer. CONCLUSIONS: This fluorescence virus-guided viable CTC capturing method provides a non-invasive alternative to tissue biopsy or surgical resection of primary tumours for companion diagnostics.

Viral transduction of the HER2-extracellular domain expands trastuzumab-based photoimmunotherapy for HER2-negative breast cancer cells.

The prognosis of HER2-positive breast cancer has been improved by trastuzumab therapy, which features high specificity and limited side effects. However, trastuzumab-based therapy has shortcomings. Firstly, HER2-targeted therapy is only applicable to HER2-expressing tumors, which comprise only 20-25% of primary breast cancers. Secondly, many patients who initially respond to trastuzumab ultimately develop disease progression. To overcome these problems, we employed virus-mediated HER2 transduction and photoimmunotherapy (PIT) which involves trastuzumab conjugated with a photosensitizer, trastuzumab-IR700, and irradiation of near-infrared light. We hypothesized that the gene transduction technique together with PIT would expand the range of tumor entities suitable for trastuzumab-based therapy and improve its antitumor activity. The HER2-extracellular domain (ECD) was transduced by the adenoviral vector, Ad-HER2-ECD, and PIT with trastuzumab-IR700 was applied in the HER2-negative cancer cells. Ad-HER2-ECD can efficiently transduce HER2-ECD into HER2-negative human cancer cells. PIT with trastuzumab-IR700 induced direct cell membrane destruction of Ad-HER2-ECD-transduced HER2-negative cancer cells. Novel combination of viral transduction of a target antigen and an antibody-based PIT would expand and potentiate molecular-targeted therapy even for target-negative or attenuated cancer cells.

In vivo imaging of lymph node metastasis with telomerase-specific replication-selective adenovirus.

Currently available methods for detection of tumors in vivo such as computed tomography and magnetic resonance imaging are not specific for tumors. Here we describe a new approach for visualizing tumors whose fluorescence can be detected using telomerase-specific replication-competent adenovirus expressing green fluorescent protein (GFP) (OBP-401). OBP-401 contains the replication cassette, in which the human telomerase reverse transcriptase (hTERT) promoter drives expression of E1 genes, and the GFP gene for monitoring viral replication. When OBP-401 was intratumorally injected into HT29 tumors orthotopically implanted into the rectum in BALB/c nu/nu mice, para-aortic lymph node metastasis could be visualized at laparotomy under a three-chip color cooled charged-coupled device camera. Our results indicate that OBP-401 causes viral spread into the regional lymphatic area and selectively replicates in neoplastic lesions, resulting in GFP expression in metastatic lymph nodes. This technology is adaptable to detect lymph node metastasis in vivo as a preclinical model of surgical navigation.

Genetically engineered oncolytic adenovirus induces autophagic cell death through an E2F1-microRNA-7-epidermal growth factor receptor axis.

Autophagy is known to have a cytoprotective role under various cellular stresses; however, it also results in robust cell death as an important safeguard mechanism that protects the organism against invading pathogens and unwanted cancer cells. Autophagy is regulated by cell signalling including microRNA (miRNA), a post-transcriptional regulator of gene expression. Here, we show that genetically engineered telomerase-specific oncolytic adenovirus induced miR-7 expression, which is significantly associated with its cytopathic activity in human cancer cells. Virus-mediated miR-7 upregulation depended on enhanced expression of the E2F1 protein. Ectopic expression of miR-7 suppressed cell viability and induced autophagy by inhibiting epidermal growth factor receptor (EGFR) expression. Our results suggest that oncolytic adenovirus induces autophagic cell death through an E2F1-miR-7-EGFR pathway in human cancer cells, providing a novel insight into the molecular mechanism of an anticancer virotherapy.

Mechanism of resistance to trastuzumab and molecular sensitization via ADCC activation by exogenous expression of HER2-extracellular domain in human cancer cells.

Trastuzumab, a humanized antibody targeting HER2, exhibits remarkable therapeutic efficacy against HER2-positive breast and gastric cancers; however, acquired resistance presents a formidable obstacle to long-term tumor responses in the majority of patients. Here, we show the mechanism of resistance to trastuzumab in HER2-positive human cancer cells and explore the molecular sensitization by exogenous expression of HER2-extracellular domain (ECD) in HER2-negative or trastuzumab-resistant human cancer cells. We found that long-term exposure to trastuzumab induced resistance in HER2-positive cancer cells; HER2 expression was downregulated, and antibody-dependent cellular cytotoxicity (ADCC) activity was impaired. We next examined the hypothesis that trastuzumab-resistant cells could be re-sensitized by the transfer of non-functional HER2-ECD. Exogenous HER2-ECD expression induced by the stable transfection of a plasmid vector or infection with a replication-deficient adenovirus vector had no apparent effect on the signaling pathway, but strongly enhanced ADCC activity in low HER2-expressing or trastuzumab-resistant human cancer cells. Our data indicate that restoration of HER2-ECD expression sensitizes HER2-negative or HER2-downregulated human cancer cells to trastuzumab-mediated ADCC, an outcome that has important implications for the treatment of human cancers.

HER3 Augmentation via Blockade of EGFR/AKT Signaling Enhances Anticancer Activity of HER3-Targeting Patritumab Deruxtecan in EGFR-Mutated Non-Small Cell Lung Cancer.

PURPOSE: EGFR-tyrosine kinase inhibitor (TKI) is a standard first-line therapy for activated EGFR-mutated non-small cell lung cancer (NSCLC). Treatment options for patients with acquired EGFR-TKI resistance are limited. HER3 mediates EGFR-TKI resistance. Clinical trials of the HER3-targeting antibody-drug conjugate patritumab deruxtecan (HER3-DXd) demonstrated its anticancer activity in EGFR-mutated NSCLC; however, the mechanisms that regulate HER3 expression are unknown. This study was conducted with the aim to clarify the mechanisms underlying HER3 regulation in EGFR-mutated NSCLC tumors and explored the strategy for enhancing the anticancer activity of HER3-DXd in EGFR-mutated NSCLC. EXPERIMENTAL DESIGN: Paired tumor samples were obtained from 48 patients with EGFR-mutated NSCLC treated with EGFR-TKI(s). HER3 expression was immunohistochemically quantified with H-score, and genomic alteration and transcriptomic signature were tested in tumors from pretreatment to post-EGFR-TKI resistance acquisition. The anticancer efficacy of HER3-DXd and osimertinib was evaluated in EGFR-mutated NSCLC cells. RESULTS: We showed augmented HER3 expression in EGFR-mutated tumors with acquired EGFR-TKI resistance compared with paired pretreatment samples. RNA sequencing revealed that repressed PI3K/AKT/mTOR signaling was associated with HER3 augmentation, especially in tumors from patients who received continuous EGFR-TKI therapy. An in vitro study also showed that EGFR-TKI increased HER3 expression, repressed AKT phosphorylation in multiple EGFR-mutated cancers, and enhanced the anticancer activity of HER3-DXd. CONCLUSIONS: Our findings help clarify the mechanisms of HER3 regulation in EGFR-mutated NSCLC tumors and highlight a rationale for combination therapy with HER3-DXd and EGFR-TKI in EGFR-mutated NSCLC.

A novel antiangiogenic effect for telomerase-specific virotherapy through host immune system.

Soluble factors in the tumor microenvironment may influence the process of angiogenesis; a process essential for the growth and progression of malignant tumors. In this study, we describe a novel antiangiogenic effect of conditional replication-selective adenovirus through the stimulation of host immune reaction. An attenuated adenovirus (OBP-301, Telomelysin), in which the human telomerase reverse transcriptase promoter element drives expression of E1 genes, could replicate in and cause selective lysis of cancer cells. Mixed lymphocyte-tumor cell culture demonstrated that OBP-301-infected cancer cells stimulated PBMC to produce IFN-gamma into the supernatants. When the supernatants were subjected to the assay of in vitro angiogenesis, the tube formation of HUVECs was inhibited more efficiently than recombinant IFN-gamma. Moreover, in vivo angiogenic assay using a membrane-diffusion chamber system s.c. transplanted in nu/nu mice showed that tumor cell-induced neovascularization was markedly reduced when the chambers contained the mixed lymphocyte-tumor cell culture supernatants. The growth of s.c. murine colon tumors in syngenic mice was significantly inhibited due to the reduced vascularity by intratumoral injection of OBP-301. The antitumor as well as antiangiogenic effects, however, were less apparent in SCID mice due to the lack of host immune responses. Our data suggest that OBP-301 seems to have antiangiogenic properties through the stimulation of host immune cells to produce endogenous antiangiogenic factors such as IFN-gamma.

In vivo biological purging for lymph node metastasis of human colorectal cancer by telomerase-specific oncolytic virotherapy.

BACKGROUND/OBJECTIVE: The aim of this study was to develop a less invasive way of targeting lymph node metastasis for the treatment of human gastrointestinal cancer. Lymphatic invasion is a major route for cancer cell dissemination, and adequate treatment of locoregional lymph nodes is required for curative treatment in patients with malignancies. METHODS: Human telomerase reverse transcription (hTERT) is the catalytic subunit of telomerase, which is highly active in cancer cells but quiescent in most normal somatic cells. OBP-301 (Telomelysin) is an attenuated adenovirus with oncolytic potency that contains the hTERT promoter element to regulate viral replication. We examined whether OBP-301 injected into the primary tumor might be useful for purging micrometastasis from regional lymph nodes in an orthotopic colorectal cancer model. RESULTS: OBP-301 was intratumorally injected into HT29 tumors orthotopically implanted into the rectum in BALB/c nu/nu mice. By using a highly sensitive quantitative PCR analysis that targets the human-specific Alu sequence, we showed that OBP-301 caused viral spread into the regional lymphatic area and selectively replicated in neoplastic lesions, resulting in tumor-cell-specific death in metastatic lymph nodes. Moreover, although the surgical removal of primary tumors increased the tendency of lymph node metastasis, preoperative intratumoral injection of virus significantly reduced lymph node metastasis. CONCLUSIONS: Our results indicate that intratumoral injection of OBP-301 mediates effective in vivo purging of metastatic tumor cells from regional lymph nodes, which may help optimize treatment of human cancer, especially gastrointestinal malignancies.

Preclinical evaluation of synergistic effect of telomerase-specific oncolytic virotherapy and gemcitabine for human lung cancer.

A phase I dose-escalation study of telomerase-specific oncolytic adenovirus, OBP-301 (Telomelysin), is now under way in the United States to assess feasibility and to characterize its pharmacokinetics in patients with advanced solid tumors. The present preclinical study investigates whether OBP-301 and a chemotherapeutic agent that is commonly used for lung cancer treatment, gemcitabine, are able to enhance antitumor effects in vitro and in vivo. The antitumor effects of OBP-301 infection and gemcitabine were evaluated by 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt assay. In vivo antitumor effects of intratumoral injection of OBP-301 in combination with systemic administration of gemcitabine were assessed on nu/nu mice s.c. xenografted with human lung tumors. OBP-301 infection combined with gemcitabine resulted in very potent synergistic cytotoxicity in human lung cancer cells. The three human lung cancer cell lines treated with OBP-301 for 24 hours tended to accumulate in S phase compared with controls. The proportion of cells in S phase increased from 43.85% to 56.41% in H460 cells, from 46.72% to 67.09% in H322 cells, and from 38.22% to 57.67% in H358 cells. Intratumoral injection of OBP-301 combined with systemic administration of gemcitabine showed therapeutic synergism in human lung tumor xenografts. Our data suggest that the combination of OBP-301 and gemcitabine enhances the antitumor effects against human lung cancer. We also found that the synergistic mechanism may be due to OBP-301-mediated cell cycle accumulation in S phase. These results have important implications for the treatment of human lung cancer.

Radiation with STAT3 Blockade Triggers Dendritic Cell-T cell Interactions in the Glioma Microenvironment and Therapeutic Efficacy.

PURPOSE: Patients with central nervous system (CNS) tumors are typically treated with radiotherapy, but this is not curative and results in the upregulation of phosphorylated STAT3 (p-STAT3), which drives invasion, angiogenesis, and immune suppression. Therefore, we investigated the combined effect of an inhibitor of STAT3 and whole-brain radiotherapy (WBRT) in a murine model of glioma. EXPERIMENTAL DESIGN: C57BL/6 mice underwent intracerebral implantation of GL261 glioma cells, WBRT, and treatment with WP1066, a blood-brain barrier-penetrant inhibitor of the STAT3 pathway, or the two in combination. The role of the immune system was evaluated using tumor rechallenge strategies, immune-incompetent backgrounds, immunofluorescence, immune phenotyping of tumor-infiltrating immune cells (via flow cytometry), and NanoString gene expression analysis of 770 immune-related genes from immune cells, including those directly isolated from the tumor microenvironment. RESULTS: The combination of WP1066 and WBRT resulted in long-term survivors and enhanced median survival time relative to monotherapy in the GL261 glioma model (combination vs. control P < 0.0001). Immunologic memory appeared to be induced, because mice were protected during subsequent tumor rechallenge. The therapeutic effect of the combination was completely lost in immune-incompetent animals. NanoString analysis and immunofluorescence revealed immunologic reprograming in the CNS tumor microenvironment specifically affecting dendritic cell antigen presentation and T-cell effector functions. CONCLUSIONS: This study indicates that the combination of STAT3 inhibition and WBRT enhances the therapeutic effect against gliomas in the CNS by inducing dendritic cell and T-cell interactions in the CNS tumor.

Photoimmunotherapy for cancer-associated fibroblasts targeting fibroblast activation protein in human esophageal squamous cell carcinoma.

Cancer-associated fibroblasts (CAFs) are strongly implicated in tumor progression, including in the processes of tumorigenesis, invasion, and metastasis. The targeting of CAFs using various therapeutic approaches is a novel treatment strategy; however, the efficacy of such therapies remains limited. Recently, near-infrared photoimmunotherapy (NIR-PIT), which is a novel targeted therapy employing a cell-specific mAb conjugated to a photosensitizer, has been introduced as a new type of phototherapy. In this study, we have developed a novel NIR-PIT technique to target CAFs, by focusing on fibroblast activation protein (FAP), and we evaluate the treatment efficacy in vitro and in vivo. Esophageal carcinoma cells exhibited enhanced activation of fibroblasts, with FAP over-expressed in the cytoplasm and on the cell surface. FAP-IR700-mediated PIT showed induced rapid cell death specifically for those cells in vitro and in vivo, without adverse effects. This novel therapy for CAFs, designed as local control phototherapy, was safe and showed a promising inhibitory effect on FAP+ CAFs. PIT targeting CAFs via the specific marker FAP may be a therapeutic option for CAFs in the tumor microenvironment in the future.

Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target.

Glioblastoma is highly enriched with macrophages, and osteopontin (OPN) expression levels correlate with glioma grade and the degree of macrophage infiltration; thus, we studied whether OPN plays a crucial role in immune modulation. Quantitative PCR, immunoblotting, and ELISA were used to determine OPN expression. Knockdown of OPN was achieved using complementary siRNA, shRNA, and CRISPR/Cas9 techniques, followed by a series of in vitro functional migration and immunological assays. OPN gene-deficient mice were used to examine the roles of non-tumor-derived OPN on survival of mice harboring intracranial gliomas. Patients with mesenchymal glioblastoma multiforme (GBM) show high OPN expression, a negative survival prognosticator. OPN is a potent chemokine for macrophages, and its blockade significantly impaired the ability of glioma cells to recruit macrophages. Integrin αvß5 (ITGαvß5) is highly expressed on glioblastoma-infiltrating macrophages and constitutes a major OPN receptor. OPN maintains the M2 macrophage gene signature and phenotype. Both tumor-derived and host-derived OPN were critical for glioma development. OPN deficiency in either innate immune or glioma cells resulted in a marked reduction in M2 macrophages and elevated T cell effector activity infiltrating the glioma. Furthermore, OPN deficiency in the glioma cells sensitized them to direct CD8+ T cell cytotoxicity. Systemic administration in mice of 4-1BB-OPN bispecific aptamers was efficacious, increasing median survival time by 68% (P < 0.05). OPN is thus an important chemokine for recruiting macrophages to glioblastoma, mediates crosstalk between tumor cells and the innate immune system, and has the potential to be exploited as a therapeutic target.

A Novel HER3-Targeting Antibody-Drug Conjugate, U3-1402, Exhibits Potent Therapeutic Efficacy through the Delivery of Cytotoxic Payload by Efficient Internalization.

PURPOSE: HER3 is a compelling target for cancer treatment; however, no HER3-targeted therapy is currently clinically available. Here, we produced U3-1402, an anti-HER3 antibody-drug conjugate with a topoisomerase I inhibitor exatecan derivative (DXd), and systematically investigated its targeted drug delivery potential and antitumor activity in preclinical models. EXPERIMENTAL DESIGN: In vitro pharmacologic activities and the mechanisms of action of U3-1402 were assessed in several human cancer cell lines. Antitumor activity of U3-1402 was evaluated in xenograft mouse models, including patient-derived xenograft (PDX) models. Safety assessments were also conducted in rats and monkeys. RESULTS: U3-1402 showed HER3-specific binding followed by highly efficient cancer cell internalization. Subsequently, U3-1402 was translocated to the lysosome and released its payload DXd. While U3-1402 was able to inhibit HER3-activated signaling similar to its naked antibody patritumab, the cytotoxic activity of U3-1402 in HER3-expressing cells was predominantly mediated by released DXd through DNA damage and apoptosis induction. In xenograft mouse models, U3-1402 exhibited dose-dependent and HER3-dependent antitumor activity. Furthermore, U3-1402 exerted potent antitumor activity against PDX tumors with HER3 expression. Acceptable toxicity was noted in both rats and monkeys. CONCLUSIONS: U3-1402 demonstrated promising antitumor activity against HER3-expressing tumors with tolerable safety profiles. The activity of U3-1402 was driven by HER3-mediated payload delivery via high internalization into tumor cells.

Combination of oncolytic adenovirotherapy and Bax gene therapy in human cancer xenografted models. Potential merits and hurdles for combination therapy.

Cancer gene therapy and oncolytic virotherapy have been studied extensively. However, their clinical application is hampered by their weak anticancer activity. We previously constructed a replicating adenovirus (OBP-301, Telomelysin), in which the human telomerase reverse transcriptase (hTERT) promoter drives expression of the adenoviral E1 genes, and causes selective lysis of human cancer cells. We hypothesized that combination adenoviral therapy containing OBP-301 and a nonreplicating adenovirus expressing the proapoptotic Bax gene could overcome the weakness and augment the anticancer efficacy of each modality. Combination treatment resulted in marked Bax protein expression and enhanced efficacy in in vitro cell viability assay, when compared with either single treatment. However, combination treatment was not as effective in suppressing both subcutaneous and pleural disseminated tumors compared with OBP-301 treatment alone. Further investigation revealed that combination treatment resulted in suppressed E1A protein expression associated with reduced viral replication. Our results suggest that Bax gene therapy in combination with oncolytic adenovirotherapy potentially augments their antitumor activity, but further improvements may be required to maximize the combinatorial effect in vivo, for the Bax gene expression to avoid interference with production of the oncolytic virus.

Establishment of biological and pharmacokinetic assays of telomerase-specific replication-selective adenovirus.

The use of replication-selective tumor-specific viruses represents a novel approach for the treatment of neoplastic disease. We constructed an attenuated adenovirus, telomerase-specific replication-selective adenovirus (TRAD), in which the human telomerase reverse transcriptase promoter element drives the expression of the E1A and E1B genes linked with an internal ribosome entry site (IRES). Forty-eight hours after TRAD infection at a multiplicity of infection of 1.0, the cell viability of H1299 human lung cancer cells was consistently less than 50% and therefore this procedure could be used as a potency assay to assess the biological activity of TRAD. We also established a quantitative real-time polymerase chain reaction (PCR) analysis with consensus primers for either the adenovirus E1A or IRES sequence. The linear ranges of quantitation with E1A and IRES primers were 10(3)-10(8) and 10(2)-10(8) plaque-forming units/mL in the plasma, respectively. The PCR analysis demonstrated that the levels of E1A in normal tissues were more than 10(3) lower than in the tumors of A549 human lung tumor xenografts in nu/nmicro mice at 28 days after intratumoral injection. Our results suggest that the cell-killing assay against H1299 cells and real-time PCR can be used to assess the biological activity and biodistribution of TRAD in clinical trials.