Oncolytic Replication of E1b-Deleted Adenoviruses.

Various viruses have been studied and developed for oncolytic virotherapies. In virotherapy, a relatively small amount of viruses used in an intratumoral injection preferentially replicate in and lyse cancer cells, leading to the release of amplified viral particles that spread the infection to the surrounding tumor cells and reduce the tumor mass. Adenoviruses (Ads) are most commonly used for oncolytic virotherapy due to their infection efficacy, high titer production, safety, easy genetic modification, and well-studied replication characteristics. Ads with deletion of E1b55K preferentially replicate in and destroy cancer cells and have been used in multiple clinical trials. H101, one of the E1b55K-deleted Ads, has been used for the treatment of late-stage cancers as the first approved virotherapy agent. However, the mechanism of selective replication of E1b-deleted Ads in cancer cells is still not well characterized. This review will focus on three potential molecular mechanisms of oncolytic replication of E1b55K-deleted Ads. These mechanisms are based upon the functions of the viral E1B55K protein that are associated with p53 inhibition, late viralmRNAexport, and cell cycle disruption.

Potent anti-tumour activity of a novel conditionally replicating adenovirus for melanoma via inhibition of migration and invasion.

BACKGROUND: Conditionally replicating adenoviruses (CRAds) represent a novel class of oncological therapeutic agents. One strategy to ensure tumour targeting is to place the essential viral genes under the control of tumour-specific promoters. Ki67 has been selected as a cancer gene therapy target, as it is expressed in most malignant cells but is barely detectable in most normal cells. This study aimed to investigate the effects of a Ki67 promoter-controlled CRAd (Ki67-ZD55-IL-24) on the proliferation and apoptosis of melanoma cells. METHODS: Melanoma cells were independently treated with Ki67-ZD55-IL-24, ZD55-IL-24, Ki67-ZD55, and ZD55-EGFP. The cytotoxic potential of each treatment was assessed using cell viability measurements. Cell migration and invasion were assayed using cell migration and invasion assays. Apoptosis was assayed using the annexin V-FITC assay, western blotting, reverse transcriptase PCR (RT-PCR), haematoxylin and eosin (H&E) staining, and the TUNEL assay. RESULTS: Our results showed that Ki67-ZD55-IL-24 had significantly enhanced anti-tumour activity as it more effectively induced apoptosis in melanoma cells than the other agents. Ki67-ZD55-IL-24 also caused the most significant inhibition of cell migration and invasion of melanoma cells. Furthermore, apoptosis was induced more effectively in melanoma xenografts in nude mice. CONCLUSIONS: This strategy holds promising potential for the further development of an effective approach to treat malignant melanoma.

2-aminopurine enhances the oncolytic activity of an E1b-deleted adenovirus in hepatocellular carcinoma cells.

Adenoviruses with deletions of viral genes have been extensively studied as potential cancer therapeutics. Although a high degree of cancer selectivity has been demonstrated with these conditionally replicating adenoviruses, low levels of virus replication can be detected in normal cells. Furthermore, these mutations were also found to reduce the activity of the replicating viruses in certain cancer cells. Recent studies have shown that co-administration of chemotherapeutic drugs may increase the activity of these viruses without affecting their specificity. We constructed an adenovirus with deletions of both the E1b and the VA-RNA genes and found that replication of this virus was selective for human hepatocellular carcinoma (HCC) cell lines when compared to normal cell lines. Furthermore, we show that 2-aminopurine (2'AP) treatment selectively enhanced virus replication and virus-mediated death of HCC cells. 2'AP did not compensate for the loss of VA-RNA activities, but rather the loss of an E1b-55K activity, such as the DNA damage response, suggesting that co-administration of 2'AP derivatives that block host DNA damage response, may increase the oncolytic activity of AdΔE1bΔVA without reducing its selectivity for HCC cells.

E1B-55 kDa-defective adenoviruses activate p53 in mesothelioma and enhance cytotoxicity of anticancer agents.

INTRODUCTION: Genetic characterization of malignant mesothelioma shows a homozygous deletion of the INK4A/ARF locus, which results in inactivation of the p53 pathways. METHODS: We examined possible antitumor effects of adenoviruses with a deletion of the E1B-55kD gene (Ad-delE1B55) on mesothelioma and investigated combinatory actions with the first-line chemotherapeutic agents. RESULTS: Ad-delE1B55 produced cytotoxicity on mesothelioma cells, which was associated with p53 phosphorylation, pRb dephosphorylation, and cleavage of caspases. Ad-delE1B55-infected cells displayed hyperploidy at the cell-cycle analysis and showed enlarged nuclear configurations. Combination of Ad-delE1B55 plus cisplatin or pemetrexed produced antitumor effects in vitro. Furthermore, Ad-delE1B55 and cisplatin showed combinatory effects in an orthotopic animal model. CONCLUSIONS: Cell death caused by Ad-delE1B55 is attributable to cell-cycle arrest at M-phase checkpoint followed by activated apoptotic pathways, and combination of the first-line chemotherapeutic agents and the oncolytic adenovirus is a potential therapeutic for mesothelioma.

Downregulation of Mcl-1 synergizes the apoptotic response to combined treatment with cisplatin and a novel fiber chimeric oncolytic adenovirus.

The aim of this study was to examine the effects of SG511, a novel fiber chimeric oncolytic adenovirus with E1B 55-kDa deleted, combined with cisplatin on cancer cells and to identify their underlying mechanisms. The combined effect of SG511 and cisplatin on HeLa and HT-29 cells was assessed by a crystal violet assay and an MTT assay, followed by combination index analysis. Cell apoptosis was evaluated by DAPI staining and visualized by fluorescein-mediated signal detection. Mitochondrial membrane potential was detected by flow cytometric analysis of Rhodamine 123 accumulation. The activation of the caspase pathway and the expression of Bcl-2 family proteins were examined by western blotting. Results show that SG511 vector infected various human cancer cell lines and induced growth inhibition effectively. Of note, SG511 synergistically enhanced the anti-proliferative activity of cisplatin, a DNA-damaging agent, against HeLa and HT-29 cells in vitro, concomitantly with increased apoptosis and activation of the mitochondrial pathway. Furthermore, treatment with SG511 alone or in combination with cisplatin resulted in reduced expression the anti-apoptotic Bcl-2 family member Mcl-1 in HeLa and HT-29 cells. Importantly, this combination did not increase the growth inhibitory effects of cisplatin on human normal liver cells. Collectively, SG511, a novel fiber chimeric oncolytic adenovirus, sensitizes cancer cells to apoptosis by reducing anti-apoptotic Mcl-1 protein levels.

Transthyretin-driven oncolytic adenovirus suppresses tumor growth in orthotopic and ascites models of hepatocellular carcinoma.

Strategies to increase antitumor efficacy of oncolytic adenoviruses are actively investigated. We have previously shown that E1B-55 kDa-deleted adenovirus, designated Ad5WS1, has therapeutic potential for treating hepatocellular carcinoma (HCC). To achieve HCC-restricted replication of oncolytic adenovirus, we generated Ad5WS2, an E1B-55 kDa-deleted adenovirus with its E1A gene driven by the liver-specific transthyretin promoter. Our results showed that Ad5WS2 could replicate within tumor cells where the transthyretin gene was expressed. Mouse transthyretin promoter was active in murine and human HCC cells, but relatively quiescent in cells of non-liver origin. Ad5WS2 caused severe cytolytic effect on HCC cells, but was much attenuated in non-HCC cells. Peritoneal administration of Ad5WS2 into mice bearing liver tumors grown in ascites resulted in enhanced survival. In an orthotopic HCC model, Ad5WS2, when systemically administered, exerted higher antitumor effects than Ad5WS1. Lack of viral replication in normal organs and minimal hepatic toxicity was noted after Ad5WS2 treatment. Furthermore, the antitumor effect of Ad5WS2 could be enhanced when combined with chemotherapeutic agent cisplatin in the ascites tumor model. These results suggest that E1B-55 kDa-deleted adenovirus driven by the transthyretin promoter may be a safer and more efficacious oncolytic agent for the treatment of primary and metastatic HCC.

Combination of ZD55-MnSOD therapy with 5-FU enhances antitumor efficacy in colorectal cancer.

PURPOSE: ZD55-MnSOD is an E1B 55 kDa-deleted replication-competent adenovirus and armed with the therapeutic gene MnSOD. The expression of the therapeutic gene MnSOD increases with the selective replication of the oncolytic adenovirus (ZD55) so that ZD55-MnSOD has more significant activity than the replicate defective adenovirus Ad-MnSOD in vitro and in vivo. The tumor cannot be completely eradicated only with ZD55-MnSOD, although ZD55-MnSOD has obvious antitumor activity. 5-fluorouracil (5-FU) is still the most effective adjuvant therapy for patients with colorectal cancer. METHODS: We reasoned that combined treatment of cancer cells with ZD55-MnSOD and 5-FU might have a synergistic effect. In vitro experiments with SW620 colorectal carcinoma cell line demonstrated that it was sensitive to ZD55-MnSOD, especially most sensitive to ZD55-MnSOD plus 5-FU treatment. Treatment with both ZD55-MnSOD and 5-FU could induce more significant apoptosis in cancer cells compared with ZD55-MnSOD or 5-FU alone, respectively. A better antitumor activity was observed by ZD55-MnSOD plus 5-fluorouracil (5-FU) treatment. Tumor growth was greatly inhibited by this combined treatment, and animal survival time increased. CONCLUSION: These results show that, by using the combination therapies, a significant decrease in tumor mass can be achieved, which suggest that ZD55-MnSOD in combination with 5-FU may have potential clinical implications.

Complete elimination of colorectal tumor xenograft by combined manganese superoxide dismutase with tumor necrosis factor-related apoptosis-inducing ligand gene virotherapy.

Manganese superoxide dismutase (MnSOD) is a latent tumor suppressor gene. To investigate the therapeutic effect of MnSOD and its mechanisms, a replication-competent recombinant adenovirus with E1B 55-kDa gene deletion (ZD55) was constructed, and human MnSOD and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) genes were inserted to form ZD55-MnSOD and ZD55-TRAIL. ZD55-MnSOD exhibited an inhibition in tumor cell growth approximately 1,000-fold greater than Ad-MnSOD. ZD55-TRAIL was shown to induce the MnSOD expression in SW620 cells. Accordingly, by the combined use of ZD55-MnSOD with ZD55-TRAIL (i.e., "dual gene virotherapy"), all established colorectal tumor xenografts were completely eliminated in nude mice. The evidence exists that the MnSOD overexpression led to a slower tumor cell growth both in vitro and in vivo as a result of apoptosis caused by MnSOD and TRAIL overexpression after adenoviral transduction. Our results showed that the production of hydrogen peroxide derived from MnSOD dismutation activated caspase-8, which might down-regulate Bcl-2 expression and induce Bax translocation to mitochondria. Subsequently, Bax translocation enhanced the release of apoptosis-initiating factor and cytochrome c. Cytochrome c finally triggered apoptosis by activating caspase-9 and caspase-3 in apoptotic cascade. Bax-mediated apoptosis seems to be dependent on caspase-8 activation because the inhibition of caspase-8 prevented Bid processing and Bax translocation. In conclusion, our dual gene virotherapy completely eliminated colorectal tumor xenografts via enhanced apoptosis, and this novel strategy points toward a new direction of cancer treatment.

Adenovirus infection and cytotoxicity of primary mantle cell lymphoma cells.

Mantle cell lymphoma (MCL) is a distinct form of non-Hodgkin's lymphoma (NHL) derived from CD5+ B cells. MCL cells overexpress cyclin D1 as a consequence of translocation of the gene into the immunoglobulin heavy-chain gene locus. MCL is an aggressive form of NHL with frequent relapses after standard-dose chemotherapy. In this context, a variety of novel therapies for patients with MCL have been investigated. In this study, we use an expanded panel of attenuated adenoviruses to study adenovirus-mediated cytotoxicity of MCL cells. Our results demonstrate: 1) adenovirus infection of MCL cells despite the absence of receptor/coreceptor molecules known to be important for adenovirus infection of other cells types; 2) cytotoxicity of MCL cells after infection with specific adenovirus mutants; 3) a high degree of cytotoxicity after infection of some patient samples with viruses lacking the E1B 19k "antiapoptotic" gene; and 4) cytotoxicity after infection with viruses containing mutations in E1A pRb or p300 binding. The extent of cytotoxicity with the panel of viruses demonstrated interpatient variability, but 100% cytotoxicity, as determined by molecular analysis, was detected in some samples. These studies provide the foundation for: 1) the development of adenoviruses as cytotoxic agents for MCL and 2) analyses of key regulatory pathways operative in MCL cells.

Comparative effect of oncolytic adenoviruses with E1A-55 kDa or E1B-55 kDa deletions in malignant gliomas.

Replication-competent oncolytic adenoviruses hold considerable promise for treating malignant gliomas. The toxicity of the clinically tested E1B-55 kDa mutant virus is negligible; however, its full clinical potential is still being evaluated. The purpose of the present study is to compare the antiglioma activity in vitro and in vivo between Delta-24, an E1A mutant adenovirus, and RA55, an E1B-55 kDa mutant adenovirus. We selected human glioma cell lines that were tumorigenic in nude mice and express wild-type p53 (U-87 MG, D54 MG) or mutant p53 (U-251 MG, U-373 MG) protein. Our studies demonstrated that Delta-24 induced a more potent antiglioma effect in vitro than RA55. Moreover, Delta-24 replicated markedly more efficiently than RA55 in both wild-type and mutant p53 scenarios. Importantly, direct intratumoral injection of Delta-24, but not RA55, significantly suppresses tumor growth in intracranial (U-87 MG, U-251 MG) or subcutaneous (D54 MG) animal models. Staining for hexon protein detected replicating adenoviruses in xenografts infected with Delta-24, but not with RA55. Collectively, these data indicate that E1A mutant adenoviruses targeting the Rb pathway are more powerful putative agents for antiglioma therapy than E1B mutant adenoviruses, and suggest that E1A mutant adenoviruses should be tested in the clinical setting for patients with malignant gliomas.

Potent antitumor efficacy of an E1B 55kDa-deficient adenovirus carrying murine endostatin in hepatocellular carcinoma.

Data from clinical trails have shown that the antitumoral effect of ONYX-015, an E1B 55kDa-deficient adenovirus, as monotherapy is insufficient. To enhance its efficiency, CNHK200-mE, another E1B 55kDa-deficient adenovirus armed with a mouse endostatin gene was constructed and its antitumoral activities against hepatocellular carcinoma (HCC) in vitro and in vivo were investigated. The selective replication and cytotoxicity of CNHK200-mE in Hep3B and HepGII cells independent of p53 status were confirmed via TCID50 and 3-(4,5dimetylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assays. Potent tumor growth suppression on SMMC-7721 xenografts in nude mice was observed and a synergistic effect of the carrier virus and the therapeutic gene was suggested. Moreover, in comparison with the nonreplicative adenovirus carrying the same therapeutic gene, amplified transgene expression of mouse endostatin in vitro and in vivo were confirmed by Western blotting and ELISA assay. The effective angiogenesis inhibition and replication of CNHK200-mE in nude mice xenografts were demonstrated by immunohistochemistry. In conclusion, the recombinant adenovirus CNHK200-mE is a replication-competent oncolytic virus mediating high expression of therapeutic gene. Because CNHK200-mE is capable of replicating in and lysing HCC cells selectively with effective tumor growth suppression and antiangiogenic activity on HCC xenografts in nude mice, it holds good potential for the treatment of HCC.

[Phase III randomized clinical trial of intratumoral injection of E1B gene-deleted adenovirus (H101) combined with cisplatin-based chemotherapy in treating squamous cell cancer of head and neck or esophagus].

BACKGROUND & OBJECTIVE: H101 is an E1B-55 kDa gene-deleted replication-selective adenovirus, which showed a significant antitumor activity. This study was to compare effects and toxicities of intratumoral H101 injection combined with cisplatin plus 5-fluorouracil (PF) regimen or adriamycin plus 5-fluorouracil (AF) regimen versus PF or AF regimen alone in treating patients with head and neck or esophagus squamous cell cancer. METHODS: A total of 160 patients were recruited. PF regimen (cisplatin 20 mg/m(2) ivgtt, qd x 5d; 5-fluorouracil 500 mg/m(2) ivgtt, qd x 5d) was administered to patients have no history of PF chemotherapy,or sensitive to PF chemotherapy,while AF regimen (adriamycin 50 mg/m(2) iv,d1; 5-fluorouracil 500 mg/m(2) ivgtt, qd x 5d) was administered to patients didn't response to PF regimen. All patients were randomized to either receive intratumoral H101 injection (5.0 x 10(11)-1.5 x 10(12) VP/day for 5 consecutive days every 3 weeks) or not. Treatment repeated every 3 weeks,all patients have to receive at least 2 cycles of chemotherapy. RESULTS: Among 123 accordant patients,overall response rate of PF plus H101 group (group A1) was 78.8% (41/52),of PF alone group (group B1) was 39.6% (21/53),of AF plus H101 group (group A2) was 50.0% (7/14),of AF alone group (group B2) was 50.0% (2/4). Differences of response rates between group A1 and group B1,between group A1+A2 and group B1+B2 were significant (P=0.000). Main side effects were fever (45.7%), injection site reaction (28.3%),and influenza-like symptoms (9.8%). CONCLUSION: Intratumoral H101 injection showed a distinct efficacy in patients with squamous cell cancer of head and neck or esophagus,and was relatively safe.

Prolonged survival of mice with multiple liver metastases of human colon cancer by intravenous administration of replicable E1B-55K-deleted adenovirus with E1A expressed by CEA promoter.

Liver is the most preferential site for metastasis of colon cancer. We, in the present study, constructed a self-replicable adenovirus in which E1A is driven by a CEA promoter and E1B-55K is deleted from the E1B region (AdCEAp/Rep) and examined its effects on multiple metastases of a human colon cancer cell in a mouse xenograft model. We first showed effective replication of the virus in various CEA-producing human colon cancer cells (M7609, HT-29) and subsequent lysis of the infected cells in vitro. We then demonstrated that a single intratumoral injection of the virus (1 x 10(8) PFU/100 microl) induced a complete regression of subcutaneous tumors (M7609) inoculated into nude mice. Further, we demonstrated that systemic administration of the virus (1 x 10(8) PFU/100 microl) through the tail vein to nude mice, which 1 week prior had been inoculated with tumor cells (colon carcinoma cell line HT-29) via the spleen and showed apparent multiple metastases in the liver, effectively suppressed the metastasis formation. The mean survival time of the treated mice was significantly longer than that of the controls. Thus, the systemic administration of AdCEAp/Rep was considered to be effective on multiple liver metastases of CEA-positive colon cancer in a xenograft model.

Genetically modified adenoviruses against gliomas: from bench to bedside.

Oncolytic or tumor-selective adenoviruses are constructed as novel antiglioma therapies. After infection, the invading genetic adenoviral material is activated within the host cell. E1A and E1B adenoviral proteins are expressed immediately. E1A protein interacts with cell cycle regulatory proteins, such as retinoblastoma (Rb), driving the cell into the S phase and ensuing viral replication. The action of E1A stimulates the cellular p53 tumor suppressor system, which results in growth arrest or apoptosis, and halts adenovirus replication. However, adenoviral E1B interacts with p53 protein, preventing the DNA replication process from being abrogated by the induction of p53-mediated apoptosis. It was subsequently hypothesized that mutant adenoviruses that were unable to express wild-type E1A or E1B proteins could not replicate in normal cells with functional Rb or p53 pathways but instead would replicate and kill glioma cells that had defects in the regulation of these tumor suppressor pathways. Mutant E1B adenoviruses have already entered the clinical setting as an experimental treatment for patients with malignant gliomas. Mutant E1A adenoviruses are now in preclinical development as antiglioma therapy. In this review, the authors describe the mechanisms underlying the production of oncolytic adenoviruses, preclinical and clinical experiences with specific oncolytic adenoviruses, and the possibilities of combining mutant oncolytic adenoviruses with gene therapy or conventional therapies for managing malignant gliomas.

E1A and E1B proteins inhibit inflammation induced by adenovirus.

Replication-defective human adenovirus (Ad) group C transducing vectors, most of which have the E1A, E1B, and E3 genes deleted, are highly inflammatory despite the fact that the parental viruses typically cause subclinical or mild infections. To investigate this paradox, the roles that the E1A, E1B, and E3 genes play in inflammation were tested by using replication-incompetent viruses carrying a deletion of the preterminal protein gene. The viruses were injected into BALB/c mouse ears, and edema was monitored as a sensitive surrogate marker of inflammation. A virus deleted for the E1A 289R (transcription activating) protein was noninflammatory, and inhibited edema induced by empty virus particles. The E1A 243R and E1B 55-kDa (p53 binding) proteins play the most important roles in inhibition of inflammation by the noninflammatory virus. The E1B 19-kDa antiapoptotic protein inhibited edema when both the E1A 243R and E1B 55-kDa proteins were expressed but strongly induced edema when only one was expressed. E3 proteins had their greatest effect on the inhibition of edema induced by the E1A 289R protein. The results support a model in which inflammation is countered through a mechanism that involves complex genetic interactions between Ad early region proteins and offer promise for the design and construction of noninflammatory Ad gene therapy vectors that are relatively easy to grow and purify.

[Phase II clinical study of intratumoral H101, an E1B deleted adenovirus, in combination with chemotherapy in patients with cancer].

BACKGROUND & OBJECTIVE: In recent years,great development have been made in cancer therapeutics with replication-competent viruses (oncolytic viruses), E1B deleted adenovirus is one of promising viruses. The current study was designed to evaluate the efficacy and toxicity of intratumoral H101, a E1B-deleted adenovirus, in combination with chemotherapy on patients with cancer. METHODS: A total of 50 patients with malignant tumors in multiple centers clinical trial were treated with H101, 0.5ml 5x10(11) viral particle per day for 5 consecutive days every three weeks. Routine chemotherapy was performed at the same time. And the efficacy and toxicity were recorded. RESULTS: Among 46 valuable cases, the overall response rate was 30.4%. The response rate was 28.0% (14/50) among ITT population, including 3 complete response (CR) and 11 partial response (PR). The overall response rate of control lesion was 13.0%, including 1 case of CR and 5 cases of PR. Thus, the response rate in injected lesion is clearly higher than that in control lesion (P< 0.001). Main side effects were injection site pain (26.9%) and fever (30.2%). Grade 1 hepatic dysfunction was found in 4 patients, grade 2 in 1 patients, grade 4 in 1 patients. Grade 4 hematological toxicities were found in 4 patients. CONCLUSION: The study showed that the combination of genetically modified adenovirus (H101) and chemotherapy possessed some effect for treating the patients with refractory malignant tumors, and the toxicities were lower, well tolerated.

Replication of an E1B 55-kilodalton protein-deficient adenovirus (ONYX-015) is restored by gain-of-function rather than loss-of-function p53 mutants.

ONYX-015 (dl1520) is an E1B 55-kilodalton protein-deficient replicating adenovirus that is currently in clinical trials as an antitumor agent. On the basis of the observation that the E1B 55kD gene product is able to bind to and inactivate p53, ONYX-015's mechanism of action is proposed to involve selective replication in and killing of p53-deficient cells. While its efficacy as a therapeutic agent appears evident, the virus's mechanism of cellular selectivity, including a possible role of p53 in this regard, is less clear. Indeed, there have been a number of recent reports suggesting that the p53 status of target cells does not reliably predict ONYX-015 replication or cell killing. To address the role of p53 in ONYX-015 selectivity, we have undertaken a rigorous analysis of the behavior of this virus in small airway-derived primary human epithelial cells expressing either dominant-negative or gain-of-function mutant p53 genes. Examination of small airway epithelial cells expressing a variety of p53 mutant alleles revealed that while all were able to inhibit endogenous p53 activity, only one allele examined, 248W, demonstrated a markedly increased ability to facilitate ONYX-015 replication. This allele is a member of a group of p53 mutants (know as class I mutants) characterized by retention of global structural conformation but loss of DNA-binding activity. These observations indicate that the nature of the p53 mutation affects ONYX-015 replication, help reconcile disparate published findings, and may provide criteria by which to direct clinical application of ONYX-015.

[Safety of an E1B deleted adenovirus administered intratumorally to patients with cancer].

BACKGROUND & OBJECTIVE: In recent years, great development has been made in cancer therapeutics with replication-competent viruses (oncolytic viruses). Genetically modified adenovirus is one of promising viruses. The current study was designed to evaluate the safety of intratumoral H101, an E1B deleted adenovirus. METHODS: A total of 15 patients with malignant tumors were treated with H101 in a dose-escalation manner (from 5 x 10(7) VP to 1.5 x 10(12) VP per day for 5 consecutive days). Systemic examination was performed prior to injection. Physical signs (including weight, temperature, respiration,pulse, and blood pressure) and toxicity were observed and recorded carefully during treatment. Adenoviral DNA in plasma, urine, and swabs of oropharynx, swabs of the injection site from different time-point were determined by PCR. RESULTS: Evaluation of toxicity in all 15 cases was available. All patients tolerated well following intratumoral injection of H101. Dose limited toxicity (DLT) and serious adverse event (SAE) were not found in the course of treatment. Main side effects were injection site pain (60.0%) and fever (33.3%). Adenoviral DNA was undetectable in plasma, urine, and swabs of oropharynx, swabs of the injection site. CONCLUSION: This study showed that the toxicities of intratumoral injection of E1B deleted adenovirus (H101) were lower and tolerable. There is no evidence indicating the invasion. These results suggested that intratumorally injected H101 is safe.

Oncolysis of human gastric cancers by an E1B 55 kDa-deleted YKL-1 adenovirus.

Advanced gastric cancer cannot be treated with surgery or conventional cancer therapy, which has prompted a search for new therapeutic modalities. Previously, we and other groups showed that E1B 55 kDa-deleted recombinant adenoviruses, such as YKL-1, effectively replicate and induce cytotoxicity in p53-deficient cancer cells while sparing normal cells. Here, we investigated selective YKL-1 replication and resultant cytolysis in human gastric cancer cells. The cytopathic effects were obvious in all five gastric cancer cell lines we examined. Evaluation of p53 expression indicated that only the AGS cell line retained functionally normal p53. Nevertheless, AGS was 10-fold more sensitive to YKL-1 than the other cell lines. Transmission electron microscopy showed typical morphological alterations along with efficient replication of YKL-1 in AGS cells. Therefore, YKL-1 induces preferential cytotoxic effects in human gastric cancer cells in a p53-independent manner, making YKL-1 a promising therapeutic agent for human gastric cancers.