Cancer Cell-specific Transfection of hCas9 Gene Using Ad5F35 Vector.

BACKGROUND: The clustered regularly interspaced short palindromic repeats-associated protein 9 (CRISPR-Cas9) is thought to have promising clinical potential. However, the off-target effects of Cas9 are a major concern for its application. Therefore, we hypothesized that the adverse effects of off-target gene editing might be minimized if the human codon-optimized Streptococcus pyogenes Cas9 (hCas9) could be specifically expressed in cancer cells. MATERIALS AND METHODS: We constructed a chimeric adenoviral vector, Ad5F35-MKp-hCas9, and infected human bladder cancer cell lines with this vector. The confirmation of hCas9 gene expression was performed in 3-4 days after from infection. RESULTS: hCas9 gene expression was observed in Ad5F35-MKp-hCas9 infected bladder cancer cells but not in non-malignant cells. CONCLUSION: Our study showed that the Ad5F35-MKp-hCas9 vector is capable of expressing the hCas9 gene with high specificity in bladder cancer cells. These findings may help in minimizing the risk of off-target effects of gene editing.

Microbial Antigen-Presenting Extracellular Vesicles Derived from Genetically Modified Tumor Cells Promote Antitumor Activity of Dendritic Cells.

Tumor-derived extracellular vesicles (EVs), as tumor vaccines, carry tumor-associated antigens (TAAs), and were expected to transfer TAAs to antigen-presenting cells. However, treatment with tumor-derived EVs exhibited no obvious antitumor effect on the established tumors, likely due to their immuno-suppressive functions, and also to the poor immunogenicity of TAAs. In order to improve the immune stimulating properties, EVs expressing a highly immunogenic bacterial antigen, 6 kDa early secretory antigenic target (ESAT-6), from Mycobacterium tuberculosis were prepared by genetically modifying the parent tumor cells with a plasmid coding for ESAT-6. Cultured B16 tumor cells were transfected with a ternary complex system consisting of pDNA, polyethylenimine (PEI), and chondroitin sulfate. The cells that were transfected with the ternary complex secreted EVs with a higher number of ESAT-6 epitopes than those transfected by a conventional DNA/PEI binary complex, due to the low cytotoxicity, and durable high expression efficiency of the ternary complex systems. The EVs presenting the ESAT-6 epitope (ESAT-EV) were collected and explored as immune modulatory agents. Dendritic cells (DCs) were differentiated from mouse bone marrow cells and incubated with ESAT-EV. After incubating with the EVs for one day, the DCs expressed a significantly higher level of DC maturation marker, CD86. The DCs treated with ESAT-EV showed a significantly improved antitumor activity in tumor-bearing mice.

Cloning of carrier cells infected with oncolytic adenovirus driven by midkine promoter and biosafety studies.

BACKGROUND: A549 carrier cells infected with oncolytic adenovirus can induce complete tumor reduction of subcutaneous ovarian tumors but not intraperitoneal disseminated ovarian tumors. This appears to be a result of the insufficient antitumor effect of A549 carrier cells. Therefore, in the present study, we cloned a novel carrier cell with the aim of improving the antitumor effects. METHODS: Carrier cells infected with oncolytic adenovirus AdE3-midkine with a midkine promoter were cloned by limiting dilution. We examined the antitumor effects of these cells on subcutaneous and intraperitoneal OVHM ovarian tumors in a syngeneic mouse model. Biosafety tests were conducted in beagle dogs and rabbits. RESULTS: We cloned EHMK-51-35 carrier cells with 10-fold higher antitumor effects compared to A549 carrier cells in vitro. EHMK-51-35 carrier cells co-infected with AdE3-midkine and Ad-mGM-CSF induced a 100% complete tumor reduction in subcutaneous tumors and a 60% reduction of intraperitoneal disseminated tumors. Single-dose acute toxicity test on beagle dogs with EHMK-51-35 carrier cells co-infected with AdE3-midkine and Ad-cGM-CSF showed no serious side effects. Biologically active adenoviruses were not detected in the blood, saliva, feces, urine or whole organs. In a chronic toxicity test, VX2 tumors in rabbits were injected five times with EHMK-51-35 carrier cells infected with AdE3-midkine and these rabbits showed no serious side effects. CONCLUSIONS: Significant antitumor effects and safety of cloned EHMK-51-35 carrier cells were confirmed in intraperitoneal ovarian tumors and toxicity tests, respectively. These findings will be extended to preclinical efficacy studies using dogs and cats, with the aim of conducting human clinical trials on refractory solid tumors.

A novel, polymer-coated oncolytic measles virus overcomes immune suppression and induces robust antitumor activity.

Although various therapies are available to treat cancers, including surgery, chemotherapy, and radiotherapy, cancer has been the leading cause of death in Japan for the last 30 years, and new therapeutic modalities are urgently needed. As a new modality, there has recently been great interest in oncolytic virotherapy, with measles virus being a candidate virus expected to show strong antitumor effects. The efficacy of virotherapy, however, was strongly limited by the host immune response in previous clinical trials. To enhance and prolong the antitumor activity of virotherapy, we combined the use of two newly developed tools: the genetically engineered measles virus (MV-NPL) and the multilayer virus-coating method of layer-by-layer deposition of ionic polymers. We compared the oncolytic effects of this polymer-coated MV-NPL with the naked MV-NPL, both in vitro and in vivo. In the presence of anti-MV neutralizing antibodies, the polymer-coated virus showed more enhanced oncolytic activity than did the naked MV-NPL in vitro. We also examined antitumor activities in virus-treated mice. Complement-dependent cytotoxicity and antitumor activities were higher in mice treated with polymer-coated MV-NPL than in mice treated with the naked virus. This novel, polymer-coated MV-NPL is promising for clinical cancer therapy in the future.

Enantioselective synthesis of ß-amino acid derivatives via nickel-promoted regioselective carboxylation of ynamides and rhodium-catalyzed asymmetric hydrogenation.

We succeeded in the development of a new method for enantioselective synthesis of α-substituted-ß-amino acid derivatives. Thus, nickel(0)-promoted carboxylation of ynamide gave the α-substituted-ß-aminoacrylate derivative in a highly regioselective manner. Then, rhodium-catalyzed asymmetric hydrogenation of the α-substituted ß-aminoacrylate produced the corresponding α-substituted ß-amino acid derivative as an optically active form.

Immune activation during the implantation phase causes preeclampsia-like symptoms via the CD40-CD40 ligand pathway in pregnant mice.

The CD40 ligand (CD40L) is expressed by T cells and has a critical role in immune system regulation. Interventions targeting CD40L interactions following embryo implantation represent an approach to preventing preeclampsia (PE). To better understand the role of CD40L in PE, we developed a PE mouse model in which we examined how CD40L-induced immune activation affects embryo implantation. Blastocysts were incubated with CD40L-expressing adenovirus and then were transferred into the uterine horns of pseudopregnant ICR mice. Histology, biochemistry and flow cytometry experiments were performed to examine the characteristics of the mouse model. In early pregnancy, decidualization and spiral artery remodeling were reduced in CD40L-transfected mice (CD40L mice) compared with control mice. Hematoxylin-eosin (HE) staining revealed hemorrhaging and excess fibrin deposition at the labyrinth layer-junctional zone interface of the placenta, and PAS staining demonstrated prominent focal and segmental sclerosis with collapsed glomerular capillaries in the kidneys of the CD40L mice. Flow cytometry data showed that interferon-γ production derived from CD4(+) T cells was elevated in the splenic cells of CD40L mice. Blood pressure (measured by the tail-cuff method) and urine albumin concentrations were significantly increased in CD40L mice compared with control mice. Furthermore, the plasma concentrations of soluble Flt-1 and soluble endoglin were increased in CD40L mice, as occurs in human patients with PE. Thus, CD40L-induced T-helper cell type 1 differentiation during embryo implantation may have a critical role in the pathogenesis of a PE-like presentation in a novel mouse model of PE.

Atypical carcinoid of the uterine cervix with aggressive clinical behavior: A case report.

•We herein report a case of a 44-year-old Japanese woman diagnosed with stage IB1 atypical carcinoid of the uterine cervix.•After radical hysterectomy, she developed recurrence with aggressive clinical behavior, resistance to CPT-11 + cisplatin and paclitaxel + CBDCA chemotherapy.

Biosafety studies of carrier cells infected with a replication-competent adenovirus introduced by IAI.3B promoter.

The use of carrier cells infected with oncolytic viruses in cancer gene therapy is an attractive method because it can overcome viral immunogenicity and induce tumor immunity and significant antitumor activity. To enable human clinical trials of this treatment, acute and chronic toxicity tests must first be performed to ensure safety. IAI.3B promoter, oncolytic adenovirus AdE3-IAI.3B introduced by IAI.3B promoter, and A549 carrier cells infected with AdE3-IAI.3B were highly active in cancer cells but not in normal cells. Freeze-thawing increased the antitumor effect of A549 carrier cells by promoting the translocation of oncolytic adenovirus particles from the nucleus to the cytoplasm following the rupture of the nuclear membranes. No deaths or abnormal blood test data resulted from acute toxicity tests conducted in nude mice after a single dose. In chronic toxicity tests in rabbits, there were no serious side effects after eight doses of 1.25 × 10(7) cells/kg or less for 4 weeks; a significant immune response is known to elicit increased numbers of antiadenovirus antibodies and enlarge the spleen. From these results, it could be concluded that cancer gene therapy of recurrent solid tumors using carrier cells can be safely trialed in humans.

Concurrent chemoradiotherapy with nedaplatin in patients with stage IIA to IVA cervical carcinoma.

The present study aimed to evaluate the efficacy and toxicities of nadaplatin-based concurrent chemoradiotherapy (CCRT) in patients with stage IIA to IVA cervical carcinoma. Patients with an International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA cervical carcinoma were treated with nadaplatin-based CCRT, using high-dose rate intracavitary brachytherapy (HDR-ICBT) or radiotherapy (RT) alone, in patients with FIGO stage IIA to IVA cervical carcinoma. CCRT with nedaplatin (80 mg/m2) was administered on Days 1 and 29. The records of 17 women treated either with nadaplatin-based CCRT using HSR-ICBT (n=8) or RT alone (n=9), for stage IIA to IVA cervical carcinoma were retrospectively reviewed. The activity and toxicity were compared in the two treatment groups. Progression-free survival (PFS) and overall survival (OS) were the main endpoints. The 5-year overall survival rates in the CCRT and RT groups were 68.6 and 77.8%, respectively. The median OS of the CCRT and RT groups was 38.5 and 27.3 months, respectively. There was no significant difference in either PFS (P=0.618) or OS (P= 0.231). The most common grade 3-4 or higher toxicities in the CCRT groups were leuko-/neutropenia (37.5%). The frequency of acute grade 3-4 toxicity was higher in the CCRT compared to the RT group. However, no statistically significant difference was observed. Nedaplatin-based CCRT was safely performed. Although the prognosis of patients with FIGO stage IIA to IVA cervical carcinoma was not significantly improved, fewer distant relapses were observed in this treatment. Consequently, nedaplatin-based CCRT may be considered as a potential alternative to cisplatin-based CCRT in this patient population.

Improved gene transfer into bladder cancer cells using adenovirus vector containing RGD motif.

BACKGROUND: The transduction efficacy of adenovirus serotype 5 (Ad5) vector in high-grade human bladder cancer cells is generally extremely low due to the non-expression of coxsackie and adenoviral receptor (CAR). We investigated whether fiber-modified adenovirus vector containing an RGD motif in the HI loop of the adenovirus fiber knob could increase the transduction efficiency of Ad5 into human bladder cancer cells in vitro. MATERIALS AND METHODS: We examined the expressions of CAR, and of α(v), ß(3) and ß(5) integrin, and the transduction efficacy of fiber-modified adenovirus vector in four human bladder cancer cell lines (TCC-SUP, 253J, T24 and KK47). RESULTS: The expression of CAR was lower and those of α(v) and ß(3) integrin were higher in four human cancer cell lines compared with the control cell line, KK47. The transduction efficacy of fiber-modified adenovirus vector increased by 20- to 470-fold compared with Ad5. CONCLUSION: Fiber-modified adenovirus vector may be useful in order to establish new effective gene therapy strategies for the treatment of high-grade human bladder cancer.

Oncolytic plasmid: A novel strategy for tumor immuno-gene therapy.

The oncolytic virus is expected to proliferate in and destroy tumor cells. The virus is also thought to generate antitumor immunity. Virally infected tumor cells express viral antigens on their surfaces. Such tumor cells or their fragments would be taken up by antigen-presenting cells (APCs) together with tumor-associated antigens (TAAs), and facilitated cross-priming of tumor-specific T cells. Virus-specific protein presented on the infected cells therefore played a crucial role in the enhancement of the adaptive antitumor immunity. In this study, a plasmid encoding adenovirus protein, the adenovirus death protein (ADP), was constructed, and a very fine complex of the plasmid with polyethylenimine (PEI) and chondroitin sulfate (CS) was injected into tumor-bearing mice. Transfection of the ADP gene was shown to suppress tumor growth as effectively as granulocyte-macrophage colony-stimulating factor (GM-CSF) transfection. When mice were administered plasmid coding ADP (pDNA-ADP) to generate an immune response to ADP prior to therapy, transfection of the ADP gene induced a much higher level of tumor growth suppression than that found in the non-immunized mice. An evident synergistic effect of ADP and GM-CSF genes was also observed, and at a pDNA-ADP/pDNA-GM-CSF ratio of 4:1, significant suppression of tumor growth was achieved even in the non-immunized mice.

Antitumor effect of chondroitin sulfate-coated ternary granulocyte macrophage-colony-stimulating factor plasmid complex for ovarian cancer.

BACKGROUND: Although replication-competent viruses have been developed for treating cancers, their cytotoxic effects are insufficient as a result of infection inhibited by the generation of neutralizing antibodies, and systemic administration is difficult as a result of the life-threatening serious side-effects of virus-induced cytokine surge. To overcome these critical problems, we devised a plasmid/polycation/polyanion complex and assessed the potential of ternary plasmid complexes coated with chondroitin sulfate in gene therapy for ovarian cancer. The antitumor effects of chondroitin sulfate-coated complex as an anionic component were compared with those of hyaluronic acid on ovarian cancer. METHODS: Plasmid harboring the gene of murine granulocyte macrophage-colony-stimulating factor (mGM-CSF) was complexed with polyethyleneimine (PEI) and hyaluronic acid or chondroitin sulfate. Murine ovarian cancer cells were injected into (C57BL/6 × C3H/He) F(1) mice to prepare a subcutaneous or intraperitoneal tumor model. RESULTS: DNA/PEI was charged positively and DNA/PEI/chondroitin sulfate or DNA/PEI/hyaluronic acid was charged negatively. Plasmid-green fluorescent protein (GFP)/PEI coated with 10-kilodalton (kDa) chondroitin sulfate increased transfection efficiency compared to coating with chondroitin sulfate of higher-molecular-weight or hyaluronic acid. The transfection efficiency of GFP/PEI/10-kDa chondroitin sulfate in ovarian cancer cells was six-fold higher than that in normal cells. Intraperitoneal injection of mGM-CSF/PEI coated with 10-kDa chondroitin sulfate prolonged survival compared to that coated with hyaluronic acid. Intratumoral injection of mGM-CSF/PEI coated with 10-kDa chondroitin sulfate achieved mouse survival rates of 100%, although that with hyaluronic acid did not. CONCLUSIONS: These findings suggest that GM-CSF/PEI coated with 10-kDa chondroitin sulfate has the potential for use in gene therapy of ovarian cancer.

Intravenous injection of irradiated tumor cell vaccine carrying oncolytic adenovirus suppressed the growth of multiple lung tumors in a mouse squamous cell carcinoma model.

BACKGROUND: Although cancer therapy using replication-selective oncolytic adenoviruses has been available for many years, its anti-tumor efficacy is suboptimal as a result of low and nonspecific infectivity that depends on coxsackie adenovirus receptor expression of the target cancer and normal cells, and generation of an anti-adenovirus neutralizing antibody. In addition, concerns of triggering a severe innate immune response against the adenovirus limit the systemic administration. We developed the carrier cell-based oncolytic virus system (CBOVS) using irradiated tumor cells as carrier cells and concealing the adenovirus (Ad-IAI.3B) inside to improve the specific infectivity. We investigated the anti-tumor effect of CBOVS in a multiple lung tumor mouse model. METHODS: The ability of CBOVS to infect Ad-IAI.3B to the target cancer cells was examined in vitro in the presence of anti-adenovirus antibodies. To evaluate the systemic effect of CBOVS, we intravenously injected CBOVS into mice with lung tumors (KLN205 cell lines). RESULTS: CBOVS enhanced the infectivity of Ad-IAI.3B to tumor cells in the presence of anti-adenovirus antibodies in vitro. Intravenous injections of CBOVS produced an accumulation of the adenovirus in the lung-bearing tumors and produced a strong anti-tumor effect in vivo. Furthermore, lymphocytes collected from the CBOVS-treated mice induced an increase in cytokines related to the Th1 response (interferon-γ, interleukin-12) by pulsing with KLN205. CONCLUSIONS: These findings suggest that CBOVS could protect adenoviruses from neutralizing antibodies and systemically deliver them to lung tumors. Furthermore, CBOVS appears to have potential as a tumor cell vaccine that activates cytotoxic immunity against cancer cells.

Gene therapy for oral squamous cell carcinoma with IAI.3B promoter-driven oncolytic adenovirus-infected carrier cells.

Although replication-competent oncolytic viral vectors have been developed to improve antitumor activity, the generation of high titers of neutralizing antibodies inhibits repetitive viral infection. Many studies have reported that oncolytic virus-infected carrier cells can overcome this viral induced immunogenicity. However, the effects of oncolytic virus-infected carrier cells in human oral squamous cell carcinoma (OSCC) have not yet been examined. In the present study, simulating the clinical trial, we examined the antitumor activity of carrier cells infected with oncolytic adenovirus AdE3-IAI.3B in human OSCC. IAI.3B was highly activated in OSCC cells but not in normal cells. AdE3-IAI.3B killed OSCC cells in vitro but not normal cells. AdE3-IAI.3B-infected A549 carrier cells eradicated OSCC GFP-SAS tumors in nude mice. Anti-adenovirus neutralizing antibodies completely blocked the antitumor effect of AdE3-IAI.3B but did not block that of carrier cells. After the induction of anti-adenoviral CTL responses by immunization of adenovirus, administration of carrier cells induced complete regression of murine squamous cell carcinoma SCC7 tumors. Adenovirus-GM-CSF augmented the antitumor effect of carrier cells. The IAI.3B-driven oncolytic adenovirus-infected carrier cell system might prove useful in the treatment of OSCC and clinical trials of it should be conducted in the near future.

Carrier cell-mediated cell lysis of squamous cell carcinoma cells by squamous cell carcinoma antigen 1 promoter-driven oncolytic adenovirus.

BACKGROUND: The squamous cell carcinoma antigen (SCCA) serves as a serological marker for squamous cell carcinomas. Molecular cloning of the SCCA genomic region has revealed the presence of two tandemly arrayed genes: SCCA1 and SCCA2. SCCA1 gene is up-regulated in squamous cell carcinoma cells. We analyzed the proximal region of the SCCA1 promoter and the antitumor effect of oncolytic adenovirus driven by the SCCA1 promoter in squamous cell carcinoma cells. METHODS: The SCCA1 promoter was analyzed by dual luciferase assay and substituted with the E1A promoter to construct the oncolytic adenovirus to determine the squamous cell carcinoma-specific cell lysis. RESULTS: Deletion analysis of SCCA1 promoter identified a 175-bp core promoter region and an enhancer region at -525 to -475 bp upstream of the transcription start site. The transcriptional activity of the SCCA1 promoter was up-regulated in squamous cell carcinoma cells. Five tandem repeats of enhancer increased SCCA1 promoter activity by four-fold. Oncolytic adenovirus driven by this SCCA1 enhancer-promoter complex specifically killed squamous cell carcinoma cells in vitro and in vivo. A549 carrier cells infected with the oncolytic adenovirus induced complete regression of syngeneic squamous cell carcinoma cell tumor by overcoming immunogenicity and adenovirus-mGM-CSF augmented the antitumor effect of carrier cells. CONCLUSIONS: SCCA1 was up-regulated in squamous cell carcinoma cells and oncolytic adenovirus driven by SCCA1 promoter specifically killed these cells. These findings suggest that SCCA1 promoter is a potential target of gene therapy for squamous cell carcinoma.

Preparation of a novel adenovirus formulation with artificial envelope of multilayer polymer-coatings: therapeutic effect on metastatic ovarian cancer.

Layer-by-layer deposition of the ionic polymers onto adenovirus particles afforded the multilayer-coated virus vectors. The infectivity of the virus in the presence of anti-adenovirus antibody increased as the layer number and the viruses with five or six polymer layers allowed relatively high efficiency of reporter gene expression in vitro. Therapeutic effect of the intraperitoneal injection of the oncolytic adenovirus with quintal polymer multilayers on the mice bearing intraperitoneal metastatic ovarian cancer was examined. All the control mice injected with PBS died within 21 days after the tumor inoculation. On the other hand, the mice injected with the multilayer-coated oncolytic virus lived much longer and seven eighths of them lived >60 days without apparent accumulation of ascites. These approaches would open a new way to create a novel, safe and efficient viral gene therapy.

DNA/polyethyleneimine/hyaluronic acid small complex particles and tumor suppression in mice.

The highest barriers for non-viral vectors to an efficient in vivo gene transfection would be (1) non-specific interaction with biological molecules, and (2) large size of the DNA complex particles. Protective coating of the DNA/polyethyleneimine (PEI) complexes by hyaluronic acid (HA) effectively diminished the adverse interactions with biological molecules. Here we found HA also protected the DNA/PEI complexes against aggregation and inactivation through lyophilization-and-rehydration procedures. It allows us to prepare the concentrated very small DNA complex particles (<70 nm) suspension by preparing the complexes at highly diluted conditions, followed by lyophilized-and-rehydrated to a small volume. In vivo gene expression efficiency of the small complex was examined with mice subcutaneously inoculated with B16 melanoma cells. These formulations showed high reporter-gene expression level in tumor after intravenous injection into tumor-bearing mice. Small complex was then made of the plasmid encoding GM-CSF gene, and injected into the mice bearing subcutaneous solid B16 tumor. After intravenous injection, it induced apparent tumor growth suppression in 50% of the mice. Notably, significant therapeutic effect was detected in the mice that received intratumoral injection, and 75% of the mice were completely cured with disappearance of tumor.

Improving gene transfer in human renal carcinoma cells: Utilization of adenovirus vectors containing chimeric type 5 and type 35 fiber proteins.

The transduction efficacy of adenovirus serotype 5 (Ad5) vector in human renal carcinoma cells is generally low due to the down-regulated expression of Coxsackie and adenovirus receptor (CAR) in target cells. By contrast, the infectivity of adenovirus serotype 35 vectors depends on the binding rate to CD46 receptor, independent of CAR. In this study, we examined whether an adenovirus vector containing chimeric type 5 and type 35 fiber proteins (Ad5/F35) increases transduction efficiency compared to Ad5 vector in human renal carcinoma cells in vitro. The expression of CAR was much lower in the human renal carcinoma cells than in control HEK293 cells. By contrast, the expression of CD46 was similar and perhaps at a higher level in the human renal carcinoma cells than in the HEK293 cells. The transduction efficacy of Ad5/F35 vector was dramatically higher compared to that of Ad5 in human renal carcinoma cells, and was correlated to the expression of CD46. Thus, Ad5/35 vector may be useful for the development of novel gene therapy approaches to renal cell carcinoma.

Improved gene transfer into renal carcinoma cells using adenovirus vector containing RGD motif.

UNLABELLED: The transduction efficacy of adenovirus serotype 5 (Ad5) vector in human renal carcinoma cells is generally extremely low due to the non-expression of Coxsackie and adenoviral receptor (CAR). We investigated whether fiber-modified Ad vector containing an RGD motif in the HI loop of the Ad fiber knob could increase the transduction efficiency of Ad5 in human renal carcinoma cells in vitro. MATERIALS AND METHODS: We examined both expressions of CAR, and alpha(v), beta(3) and beta(5) integrins, and the transduction efficacy of fiber-modified adenovirus vector in all cell lines. RESULTS: The expression of CAR was lower and those of alpha(v) and beta(3) integrins were higher in all cell lines compared with control cell line, KK47. The transduction efficacy of fiber-modified Ad vector increased by 125- to 1,800-fold compared with Ad5. CONCLUSION: The fiber-modified Ad vector may be useful to establish effective new gene therapy strategies for the treatment of renal cell carcinoma.

Cyclooxygenase 2 promoter-based replication-selective adenoviral vector for hypopharyngeal cancer.

OBJECTIVE: To explore the potential clinical application of the oncolytic activity of cyclooxygenase 2 (COX-2) promoter-based, conditional, replication-selective adenovirus vector for hypopharyngeal squamous cell carcinoma. DESIGN: In vivo study and retrospective study. SETTING: Kobe University Hospital, Kobe, Japan. SUBJECTS: Expression of COX-2 in hypopharyngeal cancers treated at Kobe University Hospital was immunohistochemically investigated. In addition, nude mice bearing human hypopharyngeal cancer cells (H891) were used to analyze oncolytic activity of a conditional replication-selective adenovirus vector in which the expression of E1a, required for viral replication, is controlled by the COX-2 promoter Ad-COX2-E1a. RESULTS: In vivo assays showed significant growth suppression in the murine hypopharyngeal model. Cyclooxygenase 2 expression was observed in 75.3% of hypopharyngeal cancers, especially in differentiated tumor cells (P = .001; r = 0.433). CONCLUSION: In this study, we demonstrated the potential of oncolytic therapy using the COX-2-promoter based, conditional, replication-selective adenovirus for COX-2-expressing hypopharyngeal squamous cell carcinomas.