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Palazzi X, Pardo ID, Ritenour H, Rao DB, Bolon B, Garman RH. A Technical Guide to Sampling the Beagle Dog Nervous System for General Toxicity and Neurotoxicity Studies. Toxicol Pathol 2022; 50:432-465. [PMID: 35730663 DOI: 10.1177/01926233221099300] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Beagle dogs are a key nonrodent species in nonclinical safety evaluation of new biomedical products. The Society of Toxicologic Pathology (STP) has published "best practices" recommendations for nervous system sampling in nonrodents during general toxicity studies (Toxicol Pathol 41[7]: 1028-1048, 2013), but their adaptation to the Beagle dog has not been defined specifically. Here we provide 2 trimming schemes suitable for evaluating the unique neuroanatomic features of the dog brain in nonclinical toxicity studies. The first scheme is intended for general toxicity studies (Tier 1) to screen test articles with unknown or no anticipated neurotoxic potential; this plan using at least 7 coronal hemisections matches the STP "best practices" recommendations. The second trimming scheme for neurotoxicity studies (Tier 2) uses up to 14 coronal levels to investigate test articles where the brain is a suspected or known target organ. Collection of spinal cord, ganglia (somatic and autonomic), and nerves for dogs during nonclinical studies should follow published STP "best practices" recommendations for sampling the central (Toxicol Pathol 41[7]: 1028-1048, 2013) and peripheral (Toxicol Pathol 46[4]: 372-402, 2018) nervous systems. This technical guide also demonstrates the locations and approaches to collecting uncommonly sampled peripheral nervous system sites.
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Affiliation(s)
| | | | | | - Deepa B Rao
- Greenfield Pathology Services, Inc., Greenfield, Indiana, USA
| | | | - Robert H Garman
- Consultants in Veterinary Pathology, Inc., Murrysville, Pennsylvania, USA
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PALAZZI X, Pardo I, Sirivelu M, Newman L, Kumpf S, Qian J, Franks T, Lopes S, Liu J, Monarski L, Casinghino S, Ritenour C, Ritenour H, Dubois C, Olson J, Graves J, Alexander K, Coskran T, Lanz TA, Brady J, McCarty D, Somanathan S, Whiteley L. Biodistribution and Tolerability of AAV-PHP.B-CBh-SMN1 in Wistar Han Rats and Cynomolgus Macaques Reveal Different Toxicologic Profiles. Hum Gene Ther 2021; 33:175-187. [PMID: 34931542 PMCID: PMC8885435 DOI: 10.1089/hum.2021.116] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
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 × 1013, 5 × 1013, or 1 × 1014 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 × 1013 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.
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Affiliation(s)
- Xavier PALAZZI
- Pfizer Global Research and Development, 105623, 1, Eastern Point Road, Groton, Connecticut, United States, 06340
| | - Ingrid Pardo
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Madhu Sirivelu
- Pfizer Worldwide Research Development and Medicine, Drug Safety Research and Development, Cambridge, Massachusetts, United States
| | - Leah Newman
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Steven Kumpf
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Jessie Qian
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Tania Franks
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Sarah Lopes
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - June Liu
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Laura Monarski
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Sandra Casinghino
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Casey Ritenour
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Hayley Ritenour
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Christopher Dubois
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Jennifer Olson
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - John Graves
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Kristin Alexander
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Timothy Coskran
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Thomas A Lanz
- Pfizer Global Research and Development, 105623, Groton, Connecticut, United States
| | - Joseph Brady
- Pfizer Worldwide Research Development and Medicine, Drug Safety Research and Development, Cambridge, Massachusetts, United States
| | - Douglas McCarty
- Pfizer Worldwide Research Development and Medicine, Drug Safety Research and Development, Cambridge, Massachusetts, United States
| | - Suryanarayan Somanathan
- Pfizer Worldwide Research Development and Medicine, Drug Safety Research and Development, Cambridge, Massachusetts, United States
| | - Laurence Whiteley
- Pfizer Worldwide Research Development and Medicine, Drug Safety Research and Development, Cambridge, Massachusetts, United States
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