The Toxicologist - Society of Toxicology

and organ weights, clinical signs and pathology, and major organ histopathology.
Since the deposited doses used in this study are assumed to be over 1000 times
higher than the intended dose for human clinical use, no local respiratory or systemic
toxicity suggested development of brevenal as a human therapeutic is promising.
(Research funded by NIEHS P01 ES10594)
809 NONCLINICAL SAFETY ASSESSMENT OF AN
ANTITHROMBOTIC THERAPEUTIC PROTEIN ON
FERTILITY AND EMBRYO-FETAL DEVELOPMENT.
V. H. Chen 1 , S. Jacobs 1 , H. Ulrichts 1 , S. Priem 1 , S. Rossenu 1 , J. Leuschner 2 , J.
Baumeister 1 and J. Holz 1 . 1 Ablynx, Zwijnaarde, Belgium and 2 LPT, Hamburg,
Germany.
Ablynx develops therapeutic proteins, Nanobodies® (NB) for the use in patients
affected by various diseases including cardiovascular, oncology and inflammation.
They are based on the smallest functional fragments of naturally-occurring heavychain
antibodies. The anti-vWF therapeutic protein (ALX-0081) is a humanized,
bivalent NB that targets the platelet adhesive von Willebrand Factor (vWF). vWF is
critically involved in a variety of thrombotic pathologies, such as platelet adhesion
to areas of vascular damage in ACS and platelet string formation in patients with
TTP. The anti-vWF NB specifically blocks interaction of the A1-domain in vWF
with the platelet receptor GPIb-IX-V. Therefore, this small protein could be a powerful
inhibitor of the pathophysiology of thrombotic events in ACS and TTP. The
anti-vWF NB entered two distinct Phase II clinical development pathways as adjunctive
treatment in the acute intervention in ACS and as adjunct to plasma exchange
for the prolonged treatment of TTP. For nonclinical safety assessment,
monkey and guinea pig were identified as the relevant models. This was confirmed
via in vitro binding/efficacy and in vivo PK/PD measurements. The assessment includes
a fertility evaluation built in a 3-month toxicity studies in monkey and an
embryo-fetal toxicity study in guinea pig. The high dose was based on an anticipation
of maximum target saturation guided by a mechanistic PK model of clearance
mechanisms and drug-target relationships. ALX-0081 exhibits no sign of fertility
effects in monkey. In guinea pig, maternal to fetus transfer of ALX-0081 was
demonstrated with no toxic effects on embryo-fetal development. Interspecies differences
need to be taken account in the assessment of placental transfer of monoclonal
antibodies (mAb) mediated via FcRn receptors and small proteins without a
Fc region. The potential of small proteins comparable in size to ALX-0081 which
contains no Fc region to cross placental barriers from human, monkey or rodent is
reviewed.
810 TOPIRAMATE AND BIRTH DEFECTS: AN UPDATE.
J. M. DeSesso 1 , A. Lavin Williams 1 and G. Koren 2 . 1 Exponent, Alexandria, VA
and 2 The Motherisk Program, The Hospital for Sick Children, Toronto, ON, Canada.
Topiramate (TPM) has been associated with cleft palate in mice and limb defects in
rats and rabbits. To assess the relevance to humans of these findings, both animal
and human data of gestational exposure to TPM were evaluated. Analysis of animal
data used to support FDA approval shows that cleft palate was observed in both the
control and TPM-treated groups in a mouse developmental study, but the incidence
for all groups was within the historical control range. Further, mice are predisposed
to cleft palate. More importantly, neither rats nor rabbits exhibited elevated
cleft palate in response to gestational TPM treatment, although both species
showed a small increase in limb defects at doses much higher than those associated
with cleft palate in the mouse. In rodents, ectrodactyly (reduced number of digits)
has been shown to occur due to developmental carbonic anhydrase inhibition.
Primates do not appear to be susceptible to limb malformations due to in utero carbonic
anhydrase inhibition. To evaluate the human data for cleft palate, Medline
and Pubmed were reviewed from 1996 to July 1, 2010 for original cohort studies of
first trimester exposure to TPM, where the authors followed pregnancy outcome
and reported rates of major malformations. The comparison group consisted of all
original papers that followed cohorts of pregnant, untreated epileptic women and
reported on rates of major malformations. Four registries involving TPM treatment
and meeting the inclusion criteria were identified from Israel, North America,
Britain, and Australia, with a total of 406 pregnancies and a mean rate of major
malformations of 3.7% (95% CI=1.9-5.5%). In the comparison group (12 registries,
reporting on a total of 710 pregnancies), the mean rate of major malformations
of 3.4% (95% CI=1.9-4.8%). The risk ratio of major malformations associated
with TPM was 1.09 [95% CI=0.58 – 2.06]. In conclusion, both the animal
and human data indicate that fetuses exposed in utero to TPM should not be at increased
risk for major malformations including cleft palate or limb defects.
811 LONG-TERM PULMONARY SAFETY ASSESSMENT OF
AFREZZA IN RATS AND DOGS.
S. Greene 1 , K. Nikula 2 , J. Reynolds 3 , D. Poulin 4 , K. McInally 5 , D. Townson 1
and P. Richardson 1 . 1 MannKind Corp, Valencia, CA, 2 Seventh Wave Laboratories,
Chesterfield, MO, 3 J.A. Reynolds & Associates, Madison, CT, 4 Charles River
Laboratories, Montreal, QC, Canada and 5 ITR Laboratories, Montreal, QC, Canada.
The inhalable insulin Afrezza was evaluated in nonclinical safety studies as a
New Molecular Entity (NME) for diabetes treatment. Chronic inhalation and carcinogenicity
studies were conducted in Sprague Dawley rats and a chronic inhalation
study was conducted in Beagle dogs. Daily doses of either the novel excipient
Technosphere® (fumaryl diketopiperazine) particles or various doses of Afrezza
(insulin adsorbed to Technosphere particles) were administered by the nose-only
(rats) or oronasal (dogs) routes. Tissues were evaluated by histopathology and respiratory
cell proliferation was assessed by immunostaining of proliferating cell nuclear
antigen (PCNA). There were no test article-related changes in the laryngopharynx,
larynx, trachea, bronchi or lung of rats. Test article and Technsophere
particle findings in the nasal cavity of rats were limited to the presence of
eosinophilic globules in the olfactory and respiratory epithelium that were considered
nonspecific responses to chronic, high level administration of particulate materials.
After 39-wks in dogs, there was a low incidence of minimal to mild alveolar
and/or bronchial interstitial neutrophil infiltrate in the lungs at the high Afrezza
dose. This cellular infiltrate regressed completely during the 8-wk recovery period.
Based on evaluation of H&E stained tissues, there was no evidence of amyloid deposition
in any portion of the respiratory tract in either species. Inhalation of
Afrezza up to 104 wks in rats and 39-wks in dogs did not increase PCNA labeling
in alveoli, large bronchiolar or terminal bronchiolar tissues. Based on no test article-related
adverse findings in the lungs or increases in cell proliferation in rats or
dogs, the no adverse effect level was established in both species as the highest studied
doses. Chronic inhalation of Afrezza was well tolerated and supports the safe
use of this NME in humans over extended periods.
812 TOXICOLOGICAL EVALUATION OF LMI1195, A
NOVEL SYMPATHETIC NERVOUS SYSTEM PET
IMAGING AGENT.
M. Mistry 1 , Y. Tang 1 , D. Onthank 1 , E. Cheesman 1 , K. Baghdadi 2 , S. Watson 3 ,
K. Beard 3 and S. Robinson 1 . 1 Lantheus Medical Imaging, North Billerica, MA,
2 Analytical Chemistry, Charles River Laboratories, Senneville, QC, Canada and 3 ITR
Laboratories, Baie d’Urfé, QC, Canada. Sponsor: W. Ruddock.
LMI1195, a benzylguanidine derivative, acts as a novel norepinephrine transporter
(NET) ligand and when labeled with 18F, can be used as a radiotracer for mapping
the nerve terminals in vivo. Toxicological studies were performed with the non-radioactive
form ([19F]LMI1195) formulated in the clinical vehicle to support the
development as a cardiac neuronal PET imaging agent. Single dose IV administration
of LMI1195 in the Sprague Dawley (SD) rats and the Beagle dogs up to 0.5
mg/kg was not associated with clinical signs, changes in food intake, body weight,
clinical and gross pathology or histopathology observed over 14 days. Repeat daily
IV injections over 28 days in either SD rats or Beagle dogs with LMI1195 at 0.005,
0.05 and 0.5 mg/kg/day produced dose related exposure but no treatment related
effects (clinical, gross or histopathological changes) in either species. Toxicokinetic
analysis on Day 1 and 28 indicated Cmax increased at least proportional to dose,
rapid blood clearance, a large volume of distribution and no marked or consistent
gender differences, minimal (rat) to some drug accumulation (dog) for the 28-day
treatment period. Injections via IV and perivascular routes in the rabbit ear with
concentrations up to 500 μg/mL of LMI1195 produced no irritation beyond vehicle
control. In vitro testing with LMI1195 up to 100 μg/mL indicated no hemolysis.
Genotoxicity tests included a bacterial mutation assay, human lymphocyte
chromosome aberration assay and rat micronucleus assay up to the maximal concentration
or tolerated dose levels. Overall these genetic toxicity studies demonstrated
that LMI1195 lacks genotoxic potential. Based on these findings, the noobservable-adverse-effect-level
(NOAEL) in both the rat and dog is 0.5 mg/kg for
LMI1195 that provides a large safety margin based on body mass (~1800x) and
BSA (~300x) relative to the anticipated clinical dose (≤0.28 μg/kg) for imaging
studies.
813 EPIGENETICS, METALS, AND CANCER.
M. Costa. Department of Environmental Medicine, New York University School of
Medicine, Tuxedo, NY.
Mounting experimental data indicates that epigenetic programs of gene expression
are altered following exposure to carcinogenic chemicals. Carcinogenic metals such
as nickel, chromate, and arsenite are excellent examples of agents that cause cancer
SOT 2011 ANNUAL MEETING 175