Monoclonal antibody targeting of fibroblast growth factor receptor 1c causes cardiac valvulopathy in rats.

Fibroblast Growth Factors (FGFs) and their receptors (FGFRs) have been proposed as potential drug targets for the treatment of obesity. The aim of this study was to assess the potential toxicity in rats of three anti-FGFR1c mAbs with differential binding activity prior to clinical development. Groups of male rats received weekly injections of either one of two FGFR1c-specific mAbs or an FGFR1c/FGFR4-specific mAb at 10 mg/kg for up to 4 weeks. All three mAbs caused significant reductions in food intake and weight loss leading to some animals being euthanized early for welfare reasons. In all three groups given these mAbs, microscopic changes were seen in the bones and heart valves. In the bones of the femoro-tibial joint, thickening of the diaphyseal cortex of long bones, due to deposition of well organized new lamellar bone, indicated that an osteogenic effect was observed. In the heart, valvulopathy described as an endocardial myxomatous change affecting the mitral, pulmonary, tricuspid and aortic valves was observed in all mAb-treated animals. The presence of FGFR1 mRNA expression in the heart valves was confirmed using in situ hybridization. Targeting the FGF-FGFR1c pathway with anti-FGFR1c mAbs leads to drug induced valvulopathy in rats. In effect, this precluded the development of these mAbs as potential anti-obesity drugs. The valvulopathy observed was similar to that described for fenfluramine and dexafenfluramine. The pathogenesis of the drug-induced valvulopathy is considered FGFR1c-mediated, based on the specificity of the mAbs and FGFR1 mRNA expression in the heart valves.

The Inflammatory Caspases-1 and -11 Mediate the Pathogenesis of Dermatitis in Sharpin-Deficient Mice.

Chronic proliferative dermatitis in mice (cpdm) is a spontaneous multiorgan inflammatory disorder with pathological hallmarks similar to atopic dermatitis and psoriasis in humans. Cpdm mice lack expression of SHANK-associated RH domain-interacting protein, an adaptor of the linear ubiquitin assembly complex, which acts in the NF-κB pathway to promote inflammation and protect from apoptosis and necroptosis. Although skin inflammation in cpdm mice is driven by TNF- and RIPK1-induced cell death, the contribution of initiating innate immunity sensors and additional inflammatory pathways remains poorly characterized. In this article, we show that inflammasome signaling, including the expression and activation of the inflammatory caspase-1 and -11 and IL-1 family cytokines, was highly upregulated in the skin of cpdm mice prior to overt disease onset. Genetic ablation of caspase-1 and -11 from cpdm mice significantly reduced skin inflammation and delayed disease onset, whereas systemic immunological disease persisted. Loss of Nlrp3 also attenuated skin disease, albeit more variably. Strikingly, induction of apoptosis and necroptosis effectors was sharply decreased in the absence of caspase-1 and -11. These results position the inflammasome as an important initiating signal in skin disease pathogenesis and provide novel insights about inflammasome and cell death effector cross-talk in the context of inflammatory diseases.

Efficacy and pharmacodynamic effect of anti-CD73 and anti-PD-L1 monoclonal antibodies in combination with cytotoxic therapy: observations from mouse tumor models.

CD73 is a cell surface 5'nucleotidase (NT5E) and key node in the catabolic process generating immunosuppressive adenosine in cancer. Using a murine monoclonal antibody surrogate of Oleclumab, we investigated the effect of CD73 inhibition in concert with cytotoxic therapies (chemotherapies as well as fractionated radiotherapy) and PD-L1 blockade. Our results highlight improved survival in syngeneic tumor models of colorectal cancer (CT26 and MC38) and sarcoma (MCA205). This therapeutic outcome was in part driven by cytotoxic CD8 T-cells, as evidenced by the detrimental effect of CD8 depleting antibody treatment of MCA205 tumor bearing mice treated with anti-CD73, anti-PD-L1 and 5-Fluorouracil+Oxaliplatin (5FU+OHP). We hypothesize that the improved responses are tumor microenvironment (TME)-driven, as suggested by the lack of anti-CD73 enhanced cytopathic effects mediated by 5FU+OHP on cell lines in vitro. Pharmacodynamic analysis, using imaging mass cytometry and RNA-sequencing, revealed noteworthy changes in specific cell populations like cytotoxic T cells, B cells and NK cells in the CT26 TME. Transcriptomic analysis highlighted treatment-related modulation of gene profiles associated with an immune response, NK and T-cell activation, T cell receptor signaling and interferon (types 1 & 2) pathways. Inclusion of comparator groups representing the various components of the combination allowed deconvolution of contribution of the individual therapeutic elements; highlighting specific effects mediated by the anti-CD73 antibody with respect to immune-cell representation, chemotaxis and myeloid biology. These pre-clinical data reflect complementarity of adenosine blockade with cytotoxic therapy, and T-cell checkpoint inhibition, and provides new mechanistic insights in support of combination therapy.

Characterization of a novel potency endpoint for the evaluation of immune checkpoint blockade in humanized mice.

Introduction: Humanized mice are emerging as valuable models to experimentally evaluate the impact of different immunotherapeutics on the human immune system. These immunodeficient mice are engrafted with human cells or tissues, that then mimic the human immune system, offering an alternative and potentially more predictive preclinical model. Immunodeficient NSG mice engrafted with human CD34+ cord blood stem cells develop human T cells educated against murine MHC. However, autoimmune graft versus host disease (GvHD), mediated by T cells, typically develops 1 year post engraftment. Methods: Here, we have used the development of GvHD in NSG mice, using donors with HLA alleles predisposed to autoimmunity (psoriasis) to weight in favor of GvHD, as an endpoint to evaluate the relative potency of monoclonal and BiSpecific antibodies targeting PD-1 and CTLA-4 to break immune tolerance. Results: We found that treatment with either a combination of anti-PD-1 & anti-CTLA-4 mAbs or a quadrivalent anti-PD-1/CTLA-4 BiSpecific (MEDI8500), had enhanced potency compared to treatment with anti-PD-1 or anti-CTLA-4 monotherapies, increasing T cell activity both in vitro and in vivo. This resulted in accelerated development of GvHD and shorter survival of the humanized mice in these treatment groups commensurate with their on target activity. Discussion: Our findings demonstrate the potential of humanized mouse models for preclinical evaluation of different immunotherapies and combinations, using acceleration of GvHD development as a surrogate of aggravated antigenic T-cell response against host.

SARS-CoV-2 Spike Protein Expression In Vitro and Hematologic Effects in Mice Vaccinated With AZD1222 (ChAdOx1 nCoV-19).

Severe COVID-19 can be associated with a prothrombotic state, increasing risk of morbidity and mortality. The SARS-CoV-2 spike glycoprotein is purported to directly promote platelet activation via the S1 subunit and is cleaved from host cells during infection. High plasma concentrations of S1 subunit are associated with disease progression and respiratory failure during severe COVID-19. There is limited evidence on whether COVID-19 vaccine-induced spike protein is similarly cleaved and on the immediate effects of vaccination on host immune responses or hematology parameters. We investigated vaccine-induced S1 subunit cleavage and effects on hematology parameters using AZD1222 (ChAdOx1 nCoV-19), a simian, replication-deficient adenovirus-vectored COVID-19 vaccine. We observed S1 subunit cleavage in vitro following AZD1222 transduction of HEK293x cells. S1 subunit cleavage also occurred in vivo and was detectable in sera 12 hours post intramuscular immunization (1x1010 viral particles) in CD-1 mice. Soluble S1 protein levels decreased within 3 days and were no longer detectable 7-14 days post immunization. Intravenous immunization (1x109 viral particles) produced higher soluble S1 protein levels with similar expression kinetics. Spike protein was undetectable by immunohistochemistry 14 days post intramuscular immunization. Intramuscular immunization resulted in transiently lower platelet (12 hours) and white blood cell (12-24 hours) counts relative to vehicle. Similarly, intravenous immunization resulted in lower platelet (24-72 hours) and white blood cell (12-24 hours) counts, and increased neutrophil (2 hours) counts. The responses observed with either route of immunization represent transient hematologic changes and correspond to expected innate immune responses to adenoviral infection.

Multiparametric MRI of early tumor response to immune checkpoint blockade in metastatic melanoma.

BACKGROUND: Immune checkpoint inhibitors are now standard of care treatment for many cancers. Treatment failure in metastatic melanoma is often due to tumor heterogeneity, which is not easily captured by conventional CT or tumor biopsy. The aim of this prospective study was to investigate early microstructural and functional changes within melanoma metastases following immune checkpoint blockade using multiparametric MRI. METHODS: Fifteen treatment-naïve metastatic melanoma patients (total 27 measurable target lesions) were imaged at baseline and following 3 and 12 weeks of treatment on immune checkpoint inhibitors using: T2-weighted imaging, diffusion kurtosis imaging, and dynamic contrast-enhanced MRI. Treatment timepoint changes in tumor cellularity, vascularity, and heterogeneity within individual metastases were evaluated and correlated to the clinical outcome in each patient based on Response Evaluation Criteria in Solid Tumors V.1.1 at 1 year. RESULTS: Differential tumor growth kinetics in response to immune checkpoint blockade were measured in individual metastases within the same patient, demonstrating significant intertumoral heterogeneity in some patients. Early detection of tumor cell death or cell loss measured by a significant increase in the apparent diffusivity (Dapp) (p<0.05) was observed in both responding and pseudoprogressive lesions after 3 weeks of treatment. Tumor heterogeneity, as measured by apparent diffusional kurtosis (Kapp), was consistently higher in the pseudoprogressive and true progressive lesions, compared with the responding lesions throughout the first 12 weeks of treatment. These preceded tumor regression and significant tumor vascularity changes (Ktrans, ve, and vp) detected after 12 weeks of immunotherapy (p<0.05). CONCLUSIONS: Multiparametric MRI demonstrated potential for early detection of successful response to immune checkpoint inhibitors in metastatic melanoma.

Optimization of RNA extraction from laser captured microdissected glomeruli from formalin-fixed paraffin-embedded mouse kidney samples for Nanostring analysis.

Optimized protocols for the microdissection of specific areas from archival tissues and the subsequent RNA analysis are needed but challenging due to RNA degradation and chemical modifications. The aim of this study was to present the most appropriate protocol for utilizing mouse FFPE kidney for laser capture microdissection and Nanostring gene expression analysis. We evaluated different section thicknesses (3, 5, 10 µm), 2 RNA extraction kits (Qiagen and Roche) and different H&E staining methods to optimize microdissection and RNA extraction from glomeruli and cortical tubules samples from FFPE mouse kidney. RNA quality and quantity were assessed via Nanodrop and Qubit. The protocol providing the best results consisted of 5 µm sections, a shorter protocol for H&E staining, and RNA extracted with the Roche kit. Higher Nanostring gene counts and lower qPCR cT significantly correlated with RNA concentrations measured with the Qubit, but not with measures obtained with the Nanodrop. The Nanostring data showed that none of the genes included in the panel was differentially expressed in the cortical tubule compartment compared to the whole kidney. However, 25 genes were differentially expressed in the glomerular compartment compared to the whole kidney. Our data showed that sufficient RNA can be extracted from small compartments like mouse renal glomeruli from archival FFPE tissue, and that whole kidney analysis does not accurately represent the transcriptome state of the glomeruli, which comprise only a small proportion of the overall kidney volume.

Use of human splenocytes in an innovative humanised mouse model for prediction of immunotherapy-induced cytokine release syndrome.

OBJECTIVES: Humanised mice have emerged as valuable models for pre-clinical testing of the safety and efficacy of immunotherapies. Given the variety of models available, selection of the most appropriate humanised mouse model is critical in study design. Here, we aimed to develop a model for predicting cytokine release syndrome (CRS) while minimising graft-versus-host disease (GvHD). METHODS: To overcome donor-induced variation, we directly compared the in vitro and in vivo immune phenotype of immunodeficient NSG mice reconstituted with human bone marrow (BM) CD34+ haematopoietic stem cells (HSCs), peripheral blood mononuclear cells (PBMCs) or spleen mononuclear cells (SPMCs) from the same human donors. SPMC engraftment in NSG-dKO mice, which lack MHC class I and II, was also evaluated as a strategy to limit GvHD. Another group of mice was engrafted with umbilical cord blood (UCB) CD34+ HSCs. Induction of CRS in vivo was investigated upon administration of the anti-CD3 monoclonal antibody OKT3. RESULTS: PBMC- and SPMC-reconstituted NSG mice showed short-term survival, with engrafted human T cells exhibiting mostly an effector memory phenotype. Survival in SPMC-reconstituted NSG-dKO mice was significantly longer. Conversely, both BM and UCB-HSC models showed longer survival, without demonstrable GvHD and a more naïve T-cell phenotype. PBMC- and SPMC-reconstituted mice, but not BM-HSC or UCB-HSC mice, experienced severe clinical signs of CRS upon administration of OKT3. CONCLUSION: PBMC- and SPMC-reconstituted NSG mice better predict OKT3-mediated CRS. The SPMC model allows generation of large experimental groups, and the use of NSG-dKO mice mitigates the limitation of early GvHD.

Intratumoral IL12 mRNA Therapy Promotes TH1 Transformation of the Tumor Microenvironment.

PURPOSE: While immune checkpoint inhibitors such as anti-PD-L1 are rapidly becoming the standard of care in the treatment of many cancers, only a subset of treated patients have long-term responses. IL12 promotes antitumor immunity in mouse models; however, systemic recombinant IL12 had significant toxicity and limited efficacy in early clinical trials. EXPERIMENTAL DESIGN: We therefore designed a novel intratumoral IL12 mRNA therapy to promote local IL12 tumor production while mitigating systemic effects. RESULTS: A single intratumoral dose of mouse (m)IL12 mRNA induced IFNγ and CD8+ T-cell-dependent tumor regression in multiple syngeneic mouse models, and animals with a complete response demonstrated immunity to rechallenge. Antitumor activity of mIL12 mRNA did not require NK and NKT cells. mIL12 mRNA antitumor activity correlated with TH1 tumor microenvironment (TME) transformation. In a PD-L1 blockade monotherapy-resistant model, antitumor immunity induced by mIL12 mRNA was enhanced by anti-PD-L1. mIL12 mRNA also drove regression of uninjected distal lesions, and anti-PD-L1 potentiated this response. Importantly, intratumoral delivery of mRNA encoding membrane-tethered mIL12 also drove rejection of uninjected lesions with very limited circulating IL12p70, supporting the hypothesis that local IL12 could induce a systemic antitumor immune response against distal lesions. Furthermore, in ex vivo patient tumor slice cultures, human IL12 mRNA (MEDI1191) induced dose-dependent IL12 production, downstream IFNγ expression and TH1 gene expression. CONCLUSIONS: These data demonstrate the potential for intratumorally delivered IL12 mRNA to promote TH1 TME transformation and robust antitumor immunity.See related commentary by Cirella et al., p. 6080.

Nonalcoholic steatohepatitis severity is defined by a failure in compensatory antioxidant capacity in the setting of mitochondrial dysfunction.

AIM: To comprehensively evaluate mitochondrial (dys) function in preclinical models of nonalcoholic steatohepatitis (NASH). METHODS: We utilized two readily available mouse models of nonalcoholic fatty liver disease (NAFLD) with or without progressive fibrosis: Lepob/Lepob (ob/ob) and FATZO mice on high trans-fat, high fructose and high cholesterol (AMLN) diet. Presence of NASH was assessed using immunohistochemical and pathological techniques, and gene expression profiling. Morphological features of mitochondria were assessed via transmission electron microscopy and immunofluorescence, and function was assessed by measuring oxidative capacity in primary hepatocytes, and respiratory control and proton leak in isolated mitochondria. Oxidative stress was measured by assessing activity and/or expression levels of Nrf1, Sod1, Sod2, catalase and 8-OHdG. RESULTS: When challenged with AMLN diet for 12 wk, ob/ob and FATZO mice developed steatohepatitis in the presence of obesity and hyperinsulinemia. NASH development was associated with hepatic mitochondrial abnormalities, similar to those previously observed in humans, including mitochondrial accumulation and increased proton leak. AMLN diet also resulted in increased numbers of fragmented mitochondria in both strains of mice. Despite similar mitochondrial phenotypes, we found that ob/ob mice developed more advanced hepatic fibrosis. Activity of superoxide dismutase (SOD) was increased in ob/ob AMLN mice, whereas FATZO mice displayed increased catalase activity, irrespective of diet. Furthermore, 8-OHdG, a marker of oxidative DNA damage, was significantly increased in ob/ob AMLN mice compared to FATZO AMLN mice. Therefore, antioxidant capacity reflected as the ratio of catalase:SOD activity was similar between FATZO and C57BL6J control mice, but significantly perturbed in ob/ob mice. CONCLUSION: Oxidative stress, and/or the capacity to compensate for increased oxidative stress, in the setting of mitochondrial dysfunction, is a key factor for development of hepatic injury and fibrosis in these mouse models.

Evaluation of urinary corticosterone as a biomarker of stress in rats using fenitrothion as a chemical stressor.

Regulatory guidelines for pharmaceutical toxicity studies recommend using one dose near the maximum tolerated. At that level significant toxicities may occur, leading to systemic stress and secondary immune suppression which can be difficult to differentiate from a primary drug effect. Therefore, there is a need for a biomarker of stress applicable to toxicity studies. This study evaluated urinary corticosterone as a biomarker, using as a pharmacologic stressor fenitrothion, which was previously shown not to cause primary immune suppression. Rats were administered fenitrothion orally at 20 and 30 mg/kg daily for 2 or 8 days, with matched vehicle controls (n = 6/group). Urine was collected for 6 and 24 h, before treatment and on Day 2 and Day 8. Urine was assayed for corticosterone, separately for the first 6 h of collection and for the whole 24 h sample. Animals were euthanized on Day 3 or Day 9 and lymphoid tissue samples were collected, weighed and examined histologically. Treated rats showed neurologic signs following treatment. Findings also included time- and dose-dependent decreases in body weight and spleen and thymus weight decreases supra-proportional to body weight on Day 9. Histologic changes were mild at a dose of 20 mg/kg, but significant at 30 mg/kg, consisting of lymphocytolysis at Day 3 and lymphoid depletion at Day 9. Urine corticosterone levels were increased on Day 2 and Day 8, in the 6-h samples, but not the 24-h ones, at both dose levels. Based on the results, urine corticosterone appears to be a sensitive biomarker of systemic stress caused by fenitrothion. Other chemical stressors should be evaluated in a similar manner in order to fully validate urine corticosterone measurement as a stress biomarker.

Evaluation of the utility of popliteal lymph node examination in a cyclophosphamide model of immunotoxicity in the rat.

The objective of this study was to characterize the variability of rat lymphoid organ weights and morphology following treatment with a known immunotoxicant, with a focus on the usefulness of evaluating popliteal lymph node weight and histology. Cyclophosphamide was administered to male Sprague-Dawley rats by oral gavage at doses of 2, 7 or 12 mg/kg/day for 10 consecutive days. Left and right popliteal lymph nodes (PLN), spleen and thymus were collected at necropsy, weighed, fixed and processed for histopathology. Femoral bone marrow was also collected, fixed and processed for histology. Organ weight variability was greater for PLN than for either spleen or thymus in control animals. There was a significant but weak correlation between paired left and right PLN weights (p < 0.005; r(2) = 0.2774). Significant treatment-related decreases in lymphoid organ weights were observed in spleen and thymus at ≥ 7 mg/kg/day (p < 0.01), whereas in PLN a significant decrease (p < 0.05) was noted only at 12 mg/kg/day. The inclusion of PLN did not enhance the sensitivity of detection of systemic treatment-related changes in lymphoid organs in a rat cyclophosphamide model.

Safety and biocompatibility of a novel self-expanding nitinol carotid stent with hybrid cell design in a porcine model of neointimal hyperplasia.

BACKGROUND: Stent design may influence the outcomes, suggesting that adverse event rates vary according to free cell area and cell design. Open cell design technology of self-expandable stents, dedicated for carotid revascularisation has better deliverability, although closed cell technology is expected to cause fewer thromboembolic events. AIM: To evaluate the feasibility and vascular response of novel, hybrid cell, self-expandable nitinol stents (MER®, Balton, Poland) implanted into porcine carotid arteries. Hybrid cell design combines open and closed cell technology. METHODS: All tested stents were implanted with 10% overstretch into 10 carotid segments of Polish domestic pigs. Control angiography was obtained immediately before and after vascular interventions as well as 28 days after the procedure. Thereafter, animals were sacrificed, and the treated segments were harvested and evaluated in the independent histopathology laboratory. RESULTS: All stents were easily introduced and implanted, showing good angiographic acute outcome. At 28 days, in the angiography, all vessels were patent with no signs of thrombi or excessive neointimal formation, with the late lumen loss of -0.11 ± 0.3 mm and percentage diameter stenosis 10.18 ± 8.1%. There was a 10% increase in the vessel reference diameter when compared to baseline (4.57 ± 0.5 vs. 4.96 ± 0.3 mm, p < 0.01). In the histopathology, mean area stenosis was 17.4% and mean intimal thickness was 0.20 mm. At histopathology, the mean injury, inflammation, and fibrin scores were low. Endothelialisation was complete in all stents, and neointimal tissue appeared moderately mature as shown by the moderate mean neointimal smooth muscle score. Nonetheless, histopathology shows one stent affected by peri-strut granulomas and one stent affected by marked mineralisation. CONCLUSIONS: The novel Polish self-expandable nitinol carotid stent with hybrid cell technology shows optimal biocompatibility and a vascular healing profile, and therefore may be introduced for first-in-man application.

Citrobacter freundii septicemia in two dogs.

A 4-month-old Maltese puppy and a 7.5-year-old Collie were diagnosed with septicemia associated with Citrobacter freundii. The puppy died soon, after developing weakness and mucohemorragic diarrhea. The Collie had immune-mediated hemolytic anemia and thrombocytopenia and was treated with immunosuppressive drugs before being euthanized. Gross examination of the puppy revealed mucohemorrhagic intestinal contents. Focal necrotic hepatitis, fibrinous peritonitis, interstitial pneumonia, and hemorrhagic gastrointestinal contents were observed in the older dog. Histologically, there was a diffuse, moderate, histiocytic meningitis in the puppy and a focal fibrinonecrotic hepatitis in the adult dog. Lesions in both dogs contained numerous gram-negative rods. Citrobacter freudii is a potential cause of monomicrobic bacteraemia-septicemia in puppies or immunocompromized adult dogs. The gastrointestinal tract is probably the main site of entry.

Immunoglobulin G2 deficiency with transient hypogammaglobulinemia and chronic respiratory disease in a 6-month-old Holstein heifer.

A 6-month-old Holstein heifer that was nonresponsive to medical treatment was evaluated for chronic respiratory disease. Complete blood count and serum chemistry revealed neutrophilic leukocytosis and low globulin levels. Assays for bovine leukemia virus, bovine virus diarrhea, and bovine leukocyte adhesion deficiency were negative. Serum globulin subclass assays revealed transient low concentrations of immunoglobulin (Ig) G1 and IgA, persistent low IgG2, and subnormal IgM. Vaccination with 2 doses of multiple, inactived viruses induced seroconversion for most viruses. Flow cytometric analysis of blood lymphocyte subpopulation demonstrated an increase in CD5+ B-cells. Blood lymphocyte proliferation and neutrophil function tests were normal. Results of immunologic assays indicated IgG2 deficiency with transient hypogammaglobulinemia.

Vascular response and mechanical integrity of the new biodegradable polymer coated sirolimus-eluting PROLIM stent implanted in porcine coronary arteries.

BACKGROUND: Although durable polymer coated drug-eluting stents (DES) are standard care in percutaneous coronary interventions, new stent platforms employing biodegradable polymer based drug delivery are increasingly being used in clinical practice. AIM: To evaluate the short- (28 days) and medium-term (90 days) vascular effects of the new biodegradable polymer coated sirolimus-eluting stent - the PROLIM stent. METHODS: The objectives of the study were evaluated using standard angiographic and histological methods. In addition, the mechanical integrity of tested stents was assessed using Faxitron imaging. A total of 12 PROLIM stents, 11 biodegradable polymer only coated stents (BPCS), and 12 bare metal stents (BMS) were implanted in the coronary arteries of 16 female non-atheroslerotic domestic swine using an overstretch of 1.1:1.0. RESULTS: At 28 days, neointimal proliferation was significantly lower in the PROLIM and BMS stents compared to the BPCS stents (p ≤ 0.05). Interestingly, despite thin neointima found at this time in the PROLIM group, there was a further significant decrease in neointimal formation between 28 and 90 days (p = 0.04). Although a statistically bigger neointima was found in BPCS stents at 28 days compared to the PROLIM and BMS stents, there was a 50% decrease in the neointimal area at 90 days follow-up (p = 0.02) which reached the level seen in other groups. The endothelialisation was completed in all tested stents after 28 days. There was a significant increase of fibrin depositions in the PROLIM treated arteries at 28 days which were resorbed nearly completely at 90 days follow-up. At 28 days, the inflammatory response was found to be numerically higher in the BPCS stents (p = NS) compared to other tested groups. On the contrary, at 90 days follow-up when the degradation process of the polymer had been completed, the inflammatory reaction decreased substantially to the level seen in the PROLIM and BMS stents. Faxitron analysis of the stented arteries revealed no major abnormalities except for isolated strut fractures observed in the mid portions of two BMS stents and one BPCS stent. CONCLUSIONS: The PROLIM - a biodegradable polymer coated sirolimus-eluting stent - demonstrates very good short-term and medium-term angiographic and histological results. The lack of 'catch-up phenomenon', fast endothelialisation process, and minimal inflammatory reaction may contribute to favourable clinical outcomes using PROLIM stents.

Biochemical and pharmacological characterization of human c-Met neutralizing monoclonal antibody CE-355621.

The c-Met proto-oncogene is a multifunctional receptor tyrosine kinase that is stimulated by its ligand, hepatocyte growth factor (HGF), to induce cell growth, motility and morphogenesis. Dysregulation of c-Met function, through mutational activation or overexpression, has been observed in many types of cancer and is thought to contribute to tumor growth and metastasis by affecting mitogenesis, invasion, and angiogenesis. We identified human monoclonal antibodies that bind to the extracellular domain of c-Met and inhibit tumor growth by interfering with ligand-dependent c-Met activation. We identified antibodies representing four independent epitope classes that inhibited both ligand binding and ligand-dependent activation of c-Met in A549 cells. In cells, the antibodies antagonized c-Met function by blocking receptor activation and by subsequently inducing downregulation of the receptor, translating to phenotypic effects in soft agar growth and tubular morphogenesis assays. Further characterization of the antibodies in vivo revealed significant inhibition of c-Met activity (≥ 80% lasting for 72-96 h) in excised tumors corresponded to tumor growth inhibition in multiple xenograft tumor models. Several of the antibodies identified inhibited the growth of tumors engineered to overexpress human HGF and human c-Met (S114 NIH 3T3) when grown subcutaneously in athymic mice. Furthermore, lead candidate antibody CE-355621 inhibited the growth of U87MG human glioblastoma and GTL-16 gastric xenografts by up to 98%. The findings support published pre-clinical and clinical data indicating that targeting c-Met with human monoclonal antibodies is a promising therapeutic approach for the treatment of cancer.

Urinary corticosterone as an indicator of stress-mediated immunological changes in rats.

Drugs that target the CNS or doses of drugs near the maximum tolerated dose may cause a non-specific stress response during routine safety testing in rodents that leads to the release of corticosterone and changes immunological parameters. In situations with mild clinical signs of stress and changes to immune organs, it may be difficult to differentiate direct immunotoxicity from changes mediated by stress. To address this concern, studies were conducted to identify potential biomarker of stress in rats that could be used in routine toxicology studies. Since serial blood collections for corticosterone levels are not practical, studies were conducted to evaluate urine corticosterone and its metabolites as a potential biomarker of stress in male Sprague-Dawley rats. Exogenous corticosterone was used as a reference to identify immune system targets and determine their relative sensitivity to corticosterone. The data from rats treated with exogenous corticosterone and from rats treated with drug or chemical stressors produced linear relationships between urine corticosterone and most immunological parameters, with r-squared values greater than 0.6. Thus, quantitatively similar effects on immunological end points are produced by exogenous corticosterone and by corticosterone induced by chemical stressors with regard to their correlation to selected immunological changes. In preclinical safety testing for a new drug, the combined findings of increased urinary corticosterone and changes of the predicted magnitude and direction in blood lymphocyte and neutrophil differentials and thymus weight or cellularity would strongly suggest that the immunological effects are secondary to a drug-induced stress response. Because these results can be obtained reliably during routine preclinical evaluations, they should be useful for the weight-of-evidence approaches often used in regulatory settings.