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The programmed cell death 1 (PD-1) pathway represents a major immune checkpoint which may be engaged by cells in a tumor microenvironment to overcome active T-cell immune surveillance. Pembrolizumab (Keytruda®) is a potent and highly selective humanized monoclonal antibody (mAb) of the IgG4/κ isotype designed to directly block the interaction between PD-1 and its ligands, PD-L1 and PD-L2. The current work was focused on developing a mouse T-Dependent Antibody Response (TDAR) model using a murinized rat anti-mouse PD-1 antibody (muDX400; a rodent surrogate for pembrolizumab) to evaluate the potential impact of treatment with a PD-1 inhibitor on immune responses to an antigen challenge (e.g. HBsAg in Hepatitis B vaccine). Despite the lower binding affinity and T1/2 compared to pembrolizumab, ligand blocking data indicated muDX400 had appropriate pharmacological activity and demonstrated efficacy in mouse tumor models, thus was suitable for pharmacodynamic and vaccination studies in mice. In a vaccination study in which mice were concomitantly administered muDX400 and the Hepatitis B vaccine, muDX400 was well-tolerated and did not result in any immune-mediated adverse effects. The treatment with muDX400 was associated with a shift in the ratio between naive and memory cells in both CD4+ and CD8+ T-lymphocytes in the spleen but did not affect anti-HBsAg antibody response profile. The mouse TDAR model using the Hepatitis B vaccine and the surrogate anti-PD1 monoclonal antibody was a useful tool in the evaluation of the potential immune-mediated effects of pembrolizumab following vaccination and appears to be a suitable alternative for the nonhuman primate TDAR models utilized for other checkpoint inhibitors. [ABSTRACT FROM AUTHOR]

Adenovirus-based gene therapy offers a unique opportunity to target gene expression to the liver by systemic delivery. However, systemic administration of a first generation adenoviral construct elicits an inflammatory response leading to TNF-α-dependent liver injury. The aim of this study was to evaluate whether the systemic administration of recombinant adenovirus exacerbates a subsequent TNF-α-dependent liver injury induced by D-galactosamine and lipopolysaccharide. Surprisingly, low-dose adenovirus administration (105 particles) protects, while high-dose adenovirus (1010 particles) is associated with an exaggerated hepatic inflammatory response from a subsequent D-galactosamine and lipopolysaccharide challenge. This exacerbation is TNF-α dependent, since treatment with a TNF inhibitor fully protects against the liver injury. Moreover, intravenous administration of an adenoviral construct expressing the anti-inflammatory protein interleukin-10 reduces TNF-α appearance and attenuates the increased hepatocyte injury. Taken together, this report demonstrates potential additive effects of TNF-α responses induced by adenovirus and other inflammatory signals, and suggests that the response can be mitigated by relative adenovirus particle dose or by inhibitors, such as TNF-binding protein or interleukin 10. [ABSTRACT FROM PUBLISHER]

Adenovirus-based gene therapy offers a unique opportunity to target gene expression to the liver by systemic delivery. However, systemic administration of a first generation adenoviral construct elicits an inflammatory response leading to TNF-α-dependent liver injury. The aim of this study was to evaluate whether the systemic administration of recombinant adenovirus exacerbates a subsequent TNF-α-dependent liver injury induced by D-galactosamine and lipopolysaccharide. Surprisingly, low-dose adenovirus administration (105 particles) protects, while high-dose adenovirus (1010 particles) is associated with an exaggerated hepatic inflammatory response from a subsequent D-galactosamine and lipopolysaccharide challenge. This exacerbation is TNF-α dependent, since treatment with a TNF inhibitor fully protects against the liver injury. Moreover, intravenous administration of an adenoviral construct expressing the anti-inflammatory protein interleukin-10 reduces TNF-α appearance and attenuates the increased hepatocyte injury. Taken together, this report demonstrates potential additive effects of TNF-α responses induced by adenovirus and other inflammatory signals, and suggests that the response can be mitigated by relative adenovirus particle dose or by inhibitors, such as TNF-binding protein or interleukin 10. [ABSTRACT FROM AUTHOR]

The temporal gene expression profile during the entire process of apoptosis and cell cycle progression in response to p53 in human ovarian cancer cells was explored with cDNA microarrays representing 33?615 individual human genes. A total of 1501 genes (4.4%) were found to respond to p53 (approximately 80% of these were repressed by p53) using 2.5-fold change as a cutoff. It was anticipated that most of p53 responsive genes resulted from the secondary effect of p53 expression at late stage of apoptosis. To delineate potential p53 direct and indirect target genes during the process of apoptosis and cell cycle progression, microarray data were combined with global p53 DNA-binding site analysis. Here we showed that 361 out of 1501 p53 responsive genes contained p53 consensus DNA-binding sequence(s) in their regulatory region, approximately 80% of which were repressed by p53. This is the first time that a large number of p53-repressed genes have been identified to contain p53 consensus DNA-binding sequence(s) in their regulatory region. Hierarchical cluster analysis of these genes revealed distinct temporal expression patterns of transcriptional activation and repression by p53. More genes were activated at early time points, while more repressed genes were found after the onset of apoptosis. A small-scale quantitative chromatin immunoprecipitation analysis indicated that in vivo p53-DNA interaction was detected in eight out of 10 genes, most of which were repressed by p53 at the early onset of apoptosis, suggesting that a portion of p53 target genes in the human genome could be negatively regulated by p53 via sequence-specific DNA binding. The approaches and genes described here should aid the understanding of global gene regulatory network of p53.Oncogene (2003) 22, 3645-3654. doi:10.1038/sj.onc.1206477 [ABSTRACT FROM AUTHOR]

A cohort study was designed to evaluate the efficiency of gene transfer and whether biological activity from the expressed therapeutic gene resulted after administration of a recombinant adenovirus containing the human wild-type p53 (p53[SUPwt]) gene (rAd-p53 SCH 58500). The cohort study was conducted in five trial subjects with recurrent ovarian cancer. Each trial subject received multiple cycles of rAd-p53 SCH 58500, each cycle comprised of doses of 7.5 × 10[SUP13] particles on each of five consecutive days. Subjects were treated with rAd-p53 SCH 58500 alone during Cycle 1 and in combination with gemcitabine during the subsequent cycles. Both tumor biopsies and peritoneal aspirates were collected and evaluated for gene transfer and evidence of the biological activities of the expressed p53[SUPwt] gene. Using quantitative PCR and RT-PCR, and in situ PCR, gene transfer and expression were documented in tumor biopsies (four of five patients) collected from Cycle 1. Furthermore, upregulation of p21/WAF1, bax and mdm-2, and downregulation of survivin were observed in these same tumor biopsy samples, suggesting that intraperitoneal administration of rAd-p53 SCH 58500 leads to detectable p53 biological activity in target tumor tissue. In addition, gene transfer and its expression were observed in cells obtained from peritoneal aspirates. These fluids were mainly comprised of polymorphonuclear neutrophils, indicating that successful gene transfer can be achieved by multiple cycle intraperitoneal administration of recombinant adenovirus. [ABSTRACT FROM AUTHOR]

Reports that inhibition of thymocyte apoptosis by targeted adenovirus-induced thymic expression of human interleukin-10 (hIL-10) reduced blood bacteremia and prevented mortality in sepsis. Bcl-2 expression in thymus; Caspase-3-like activity in the thymus of septic mice; Association of thymic expresssion of hIL-10 with a generalized reduction in the magnitude of the systemic inflammatory response.

SCH58500 (ACN53) is a replication-deficient, type 5 adenovirus (Ad) expressing human wild-type p53 tumor suppressor. It is currently undergoing clinical trials as a cancer therapeutic. Many SCH58500 clinical trials incorporate an arm comparing traditional chemotherapy against chemotherapy combined with SCH58500. Paclitaxel was chosen for combination therapy in the preclinical study reported here due to its extensive use as a first-line therapy in ovarian cancer, its synergy with SCH58500 in preclinical cancer models, and its activation of p53-independent apoptosis, which might result in a "lowered threshold" for tumor cell death. SCID mice bearing human tumor xenografts were dosed with intratumoral vehicle, control Ad vector, or SCH58500, with or without paclitaxel. Real-time quantitative reverse transcriptase polymerase chain reaction assays were developed and validated to quantitate expression of p53, the p53 downstream effector gene p21, and the apoptosis-related genes, bax, bcl-2, and survivin. Protein expression was confirmed using immunohistochemical assays for p53 and p21. Only tumors injected with SCH58500 had detectable levels of exogenous p53 DNA and mRNA. After SCH58500 treatment, 3-11-fold elevations of p21 expression were observed in tumor xenografts containing nonfunctional p53 (MDA-MB-468, MDA-MB-231, MIAPaCa2, DU-145, and SK-OV-3), but no change in p21 mRNA in wild-type p53 PA-1 tumors. Immunohistochemical assays confirmed induction of p21 protein in MDAMB-468 and SK-OV-3 cells, but not in PA-1 cells. Ad vector alone or paclitaxel alone had no effect on p21 mRNA levels in most tumors. However, paclitaxel suppressed p21 expression induced by SCH58500 4-fold in DU-145 and SK-OV-3 tumors. Paclitaxel also affected expression of the housekeeping gene gapdh. There was no consistent pattern to the changes in bax, bcl-2, or survivin after SCH58500 treatment with or without paclitaxel between tumor types, although there were consistent responses within... [ABSTRACT FROM AUTHOR]

Engineered adenoviruses offer an attractive means by which gene therapy might be achieved. The first level of assurance that patients will not be put at unnecessary risk during clinical trials, are clinical lots of adenoviruses produced from cell and virus banks demonstrated to be free from adventitious agents. Similarly tested media components and equipment, and facilities that are monitored and certified, offer an additional safety measure. Characterisation and release testing of purified adenoviral bulks and product vials offer a final level of assurance for the integrity and quality of the clinical material; a check in the overall system of manufacturing adenoviral vectors under Good Manufacturing Practices. © 1997 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]