Purpose: Immune checkpoint inhibitors (ICI) targeting PD1, PDL1, or CTLA4 are associated with immunerelated adverse events (irAE) in multiple organ systems including myocarditis. The pathogenesis and early diagnostic markers for ICI-induced myocarditis are poorly understood, and there is currently a lack of laboratory animal model to enhance our understanding. We aimed to develop such a model using cynomolgus monkeys. Experimental Design: Chinese-origin cynomolgus monkeys were dosed intravenously with vehicle or nivolumab 20 mg/kg plus ipilimumab 15 mg/kg once weekly and euthanized on day 29. Results: Multiple organ toxicities were observed in cynomolgus monkeys, and were characterized by loose feces, lymphadenopathy, and mononuclear cell infiltrations of varying severity in heart, colon, kidneys, liver, salivary glands, and endocrine organs. Increased proliferation of CD4 þ and CD8 þ T lymphocytes as well as an increase in activated T cells and central memory T cells in the blood, spleen, and lymph nodes, were observed. Transcriptomic analysis suggested increased migration and activation of T cells and increased phagocytosis and antigen presentation in the heart. Mononuclear cell infiltration in myocardium was comprised primarily of T cells, with lower numbers of macrophages and occasional B cells, and was associated with minimal cardiomyocyte degeneration as well as increases in cardiac troponin-I and NT-pro-BNP. Morphologically, cardiac lesions in our monkey model are similar to the reported ICI myocarditis in humans. Conclusions: We have developed a monkey model characterized by multiple organ toxicities including myocarditis. This model may provide insight into the immune mechanisms and facilitate biomarker identification for ICI-associated irAEs.

BACKGROUND:The European Centre for the Validation of Alternative Methods (ECVAM) designed the Embryonic Stem Cell Test (EST) as a tool for classifying developmentally toxic compounds. An in vitro tool to assess developmental toxicity would be of great value to the pharmaceutical industry to help with toxicity-associated attrition. METHODS: ECVAM's EST protocol was used, but employing a different mouse embryonic stem cell (ESC) line and an alternative differentiation medium. A subset of the compounds used to validate the EST assay along with a number of in-house pharmaceutical compounds plus marketed pharmaceutical compounds were used to assess the EST performance with receptor-mediated compounds. RESULTS: Our results with ECVAM compounds mirrored ECVAM's. Compounds that were developmentally toxic in vivo were classified by the EST as moderate risk. Overall, the accuracy was 75% with the current set of data and the predictivity of low-, moderate-, and high-risk compounds was 90, 71, and 60% while the precision was 59, 86, and 100%, respectively. Interestingly, a number of the non-developmentally toxic compounds had values for the 3T3 IC 50 values, which were lower than the ESC IC 50 and ID 50, a situation not taken into account by ECVAM when designing the EST algorithm. CONCLUSIONS: The assay as currently constructed has a significant falsepositive rate (B40%), but a very low false-negative rate (B7%). Additional moderate-and high-risk compounds need to be assessed to increase confidence, accuracy, and understanding in the EST's predictivity. Birth Defects Res (Part B) 83: 104-111, 2008.

Recombinant adeno-associated viruses (AAVs) have emerged as promising vectors for human gene therapy, but some variants have induced severe toxicity in Rhesus monkeys and piglets following high-dose intravenous (IV) administration. To characterize biodistribution, transduction, and toxicity among common preclinical species, an AAV9 neurotropic variant expressing the survival motor neuron 1 ( SMN1 ) transgene (AAV-PHP.B-CBh- SMN1 ) was administered by IV bolus injection to Wistar Han rats and cynomolgus monkeys at doses of 2 × 10 13 , 5 × 10 13 , or 1 × 10 14 vg/kg. A dose-dependent degeneration/necrosis of neurons without clinical manifestations occurred in dorsal root ganglia (DRGs) and sympathetic thoracic ganglia in rats, while liver injury was not observed in rats. In monkeys, one male at 5 × 10 13 vg/kg was found dead on day 4. Clinical pathology data on days 3 and/or 4 at all doses suggested liver dysfunction and coagulation disorders, which led to study termination. Histologic evaluation of the liver in monkeys showed hepatocyte degeneration and necrosis without inflammatory cell infiltrates or intravascular thrombi, suggesting that hepatocyte injury is a direct effect of the vector following hepatocyte transduction. In situ hybridization demonstrated a dose-dependent expression of SMN1 transgene mRNA in the cytoplasm and DNA in the nucleus of periportal to panlobular hepatocytes, while quantitative polymerase chain reaction confirmed the dose-dependent presence of SMN1 transgene mRNA and DNA in monkeys. Monkeys produced a much greater amount of transgene mRNA compared with rats. In DRGs, neuronal degeneration/necrosis and accompanying findings were observed in monkeys as early as 4 days after test article administration. The present results show sensory neuron toxicity following IV delivery of AAV vectors at high doses with an early onset in Macaca fascicularis and after 1 month in rats, and suggest adding the autonomic system in the watch list for preclinical and clinical studies. Our data also suggest that the rat may be useful for evaluating the potential DRG toxicity of AAV vectors, while acute hepatic toxicity associated with coagulation disorders appears to be highly species-dependent.

BACKGROUND: Acetylsalicylic acid (ASA) is a rat teratogen, and exposures on gestational days (GDs) 9 and 10 induce diaphragm, cardiac, and midline defects. ASA inhibits members of the cyclooxygenase (COX) family and potentially members of the carbonic anhydrase (CA) family. The objective of this study was to determine whether the mRNA developmental expression pattern for any COX or CA isoform was consistent with a model in which ASA teratogenicity is mediated through direct interaction with one of these enzymes within embryos or within the adjacent ectoplacental cone (EPC) or yolk sac. METHODS: Staged embryos, over a range (GD 9.5–12) that included ASA‐sensitive and ASA‐insensitive stages of organogenesis, were assayed for COX and CA mRNA levels by three techniques: microarrays; in situ hybridization quantitated by a micro‐imager; and quantitative reverse transcription polymerase chain reaction. ASA‐ and vehicle‐treated embryos also were compared to determine whether inhibition led to upregulated COX or CA mRNA expression. RESULTS: COX‐2 mRNA was undetectable in embryos throughout organogenesis by any assay (although it was abundant in EPC). In contrast, COX‐1 mRNA was moderately abundant in embryos throughout organogenesis. One CA isoform, CA‐4, demonstrated developmentally regulated embryonic mRNA expression that coincided with ASA sensitivity. ASA exposure failed to induce upregulation of any of these mRNAs. CONCLUSIONS: Although ASA may affect the embryo indirectly through interaction with COX‐2 within EPC, failure to detect embryonic COX‐2 mRNA argues against COX‐2 functioning as a direct mediator of ASA teratogenic activity in induction of cardiac, diaphragm, and midline defects. Correlation of COX‐1 and CA‐4 expression with ASA sensitivity suggested that embryonic COX‐1 and possibly CA‐4 are much more likely candidates for mediators of ASA developmental toxicity. Birth Defects Research (Part B) 68:57–69, 2003. © 2003 Wiley‐Liss, Inc.

Real-time PCR has become increasingly important in gene expression profiling research, and it is widely agreed that normalized data are required for accurate estimates of messenger RNA (mRNA) expression. With increased gene expression profiling in preclinical research and toxicogenomics, a need for reference genes in the rat has emerged, and the studies in this area have not yet been thoroughly evaluated. The purpose of our study was to evaluate a panel of rat reference genes for variation of gene expression in different tissue types. We selected 48 known target genes based on their putative invariability. The gene expression of all targets was examined in 11 types of rat tissues using TaqMan low density array (LDA) technology. The variability of each gene was assessed using a two-step statistical model. The analysis of mean expression using multiple reference genes was shown to provide accurate and reliable normalized expression data. The least five variable genes from each specific tissue were recommended for future tissue-specific studies. Finally, a subset of investigated rat reference genes showing the least variation is recommended for further evaluation using the LDA platform. Our work should considerably enhance a researcher's ability to simply and efficiently identify appropriate reference genes for given experiments.