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Hagerstown, MD, United States

Felice B.R.,Shire Inc | Wright T.L.,Shire Inc | Boyd R.B.,Northern Biomedical Research Inc. | Butt M.T.,Tox Path Specialists LLC | And 5 more authors.
Toxicologic Pathology | Year: 2011

Recombinant human idursulfase, an intravenous enzyme replacement therapy indicated for treatment of somatic symptoms of mucopolysaccharidosis II (Hunter syndrome), is anticipated to have minimal benefit for the cognitive impairment associated with the severe phenotype. Because intrathecal (IT) administration of enzyme replacement therapy for other lysosomal enzyme disorders has shown efficacy in animal models, an IT formulation of idursulfase (idursulfase-IT) and a drug-delivery device (subcutaneous port connected to a lumbar IT catheter) were developed for treating central nervous system (CNS) involvement. In this chronic safety study, cynomolgus monkeys were dosed weekly with IV idursulfase (0.5 mg/kg) and every four weeks with idursulfase-IT (3, 30, and 100 mg) for six months, with device and vehicle controls treated similarly (n = 6, all groups). Necropsies were performed twenty-four hours post-final IT dose or after a recovery period (four weeks post-final dose in vehicle-control, 3 mg, and 100 mg IT groups: n = 6). No clinical signs or gross central nervous system lesions were observed. Compared to controls, more pronounced cellular infiltrates in brain and spinal cord meninges were noted, which largely resolved after the recovery period. Central nervous sytem levels of idursulfase-IT were dose dependent, as determined by enzyme activity and immunohistochemistry. The no-observed-adverse-effect level of idursulfase-IT was 100 mg. © 2011 by The Author(s).

Beckman D.A.,Novartis | Youreneff M.,Novartis | Butt M.T.,Tox Path Specialists LLC
Birth Defects Research Part B - Developmental and Reproductive Toxicology | Year: 2013

BACKGROUND: Oral administration of artemether in combination with lumefantrine is approved for the treatment of malaria in adults and children. In adult animals, artemether can produce neurotoxicity with intramuscular, but not oral, administration. Herein, the potential of orally administered artemether to produce neurotoxicity in juvenile rats was investigated. METHODS: In the first study, the toxicity of artemether was evaluated in juvenile rats dosed with 0, 10, 30, and 100mg/kg/day on postpartum days (ppds) 7 to 21. In-life, clinical pathology, anatomic pathology, behavioral, and toxicokinetics evaluations were performed. The second study focused on neurotoxicity during different dosing intervals, with doses of 0, 30, and 80mg/kg/day on ppds 7 to 13, and doses of 0, 30, and 120mg/kg/day on ppds 14 to 21, 22 to 28, and 29 to 36. For each dosing interval, in-life, extensive histology, toxicokinetics, and behavioral evaluations were performed. In the third study, toxicokinetics evaluations in the adult were conducted at 20 and 200mg/kg/day. RESULTS: The first study demonstrated increased mortality, renal necrosis, and brain hemorrhage at ≥30mg/kg/day with no persistent effects in surviving animals. In the second study, increased mortality, body weight effects, and a trend toward increased exposure were observed in the ppd 14 and younger animals. Neither specific neurotoxicity nor persistent effects were seen. The toxicokinetic study in adults revealed lower exposures as compared to those in the younger juvenile rats. CONCLUSIONS: As in the adult rat, oral administration of artemether in the juvenile rat is not associated with the neurotoxicity produced by intramuscular administration. © 2013 Wiley Periodicals, Inc.

A retrospective analysis of microscopic evaluation data from control (device and/or saline-treated) animals in intrathecal studies in monkeys, dogs, sheep, and rats was conducted. The studies were performed by multiple testing facilities. All slide preparation and microscopic evaluation were conducted in the laboratory of the author. The data were of observations made at the level of the catheter tip, which typically was located in the intrathecal space near the thoracolumbar region of the spinal canal. The most common microscopic changes in control animals were meningeal infiltrates, catheter track (CT) inflammation, spinal cord compression (at the CT), CT fibrosis, spinal cord gliosis (at the CT), and spinal cord nerve fiber degeneration. Although variable between studies (even within species), in general the average severity of these findings was minimal or less in control animals. CT inflammatory mass/pyogranuloma formation, a known complication following the administration of morphine at higher concentrations/doses, was noted in 3 of 25 control dogs and 2 of 77 control monkeys. These data show that inflammatory mass/pyogranuloma formation may occur in control animals, and this occurrence is most common in dogs as compared to monkeys, sheep, and rats.

Butt M.T.,Tox Path Specialists LLC | Whitney K.M.,Abbvie Inc. | Davis W.,Biogen Idec | Davis W.,Charles River Laboratories | And 3 more authors.
Toxicologic Pathology | Year: 2015

Brain sections from control cynomolgus monkeys (Macaca fascicularis) used in toxicology studies were evaluated retrospectively in order to better understand spontaneous background changes in this species. Hematoxylin and eosin-stained slides from 76 animals (38 males and 38 females) of 9 studies were examined. Eleven animals (9 males and 2 females) were each observed to have 1 to 3 findings within the brain sections examined, for a total of 19 findings. No findings were noted in the spinal cord. The most common finding was focal to multifocal perivascular infiltration of mononuclear cells, affecting the parenchyma, the meninges, or the choroid plexus. Additionally, focal gliosis was observed in 6 animals and a single focus of hemosiderin deposition (coincident with focal gliosis and mononuclear cell infiltrate) was noted in 1 animal. Most of the glial foci were composed of cells consistent with microglial cells, with or without admixed lymphocytes. All findings were of slight or minimal severity, lacked an apparent cause, and were considered incidental and of negligible biologic significance. An awareness of the spontaneous incidence of these background findings may facilitate the discernment of toxicologically relevant effects when these findings are observed. © 2014 by The Author(s).

Butt M.,Tox Path Specialists LLC | Evans M.,Pfizer | Bowman C.J.,Pfizer | Cummings T.,Pfizer | And 3 more authors.
Toxicological Sciences | Year: 2014

Tanezumab, an antibody to nerve growth factor, was administered to pregnant cynomolgus monkeys at 0, 0.5, 4, and 30 mg/kg weekly, beginning gestation day (GD) 20 through parturition (~GD165). Maternal tanezumab administration appeared to increase stillbirths and infant mortality, but no consistent pattern of gross and/or microscopic change was detected to explain the mortality. Offspring exposed in utero were evaluated at 12 months of age using light microscopy (all tissues), stereology (basal forebrain cholinergic and dorsal root ganglia neurons), and morphometry (sural nerve). Light microscopy revealed decreased number of neurons in sympathetic ganglia (superior mesenteric, cervicothoracic, and ganglia in the thoracic sympathetic trunk). Stereologic assessment indicated an overall decrease in dorsal root ganglion (thoracic) volume and number of neurons in animals exposed to tanezumab 4 mg/kg (n1/49) and 30 mg/kg (n1/41). At all tanezumab doses, the sural nerve was small due to decreases in myelinated and unmyelinated axons. Existing axons/myelin sheaths appeared normal when viewed with light and transmission electron microscopy. There was no indication of tanezumab-related, active neuron/nerve fiber degeneration/necrosis in any tissue, indicating decreased sensory/sympathetic neurons and axonal changes were due to hypoplasia or atrophy. These changes in the sensory and sympathetic portions of the peripheral nervous system suggest some degree of developmental neurotoxicity, although what effect, if any, the changes had on normal function and survival was not apparent. Overall, these changes were consistent with published data from rodent studies. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology.

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