4-(4-bromo-3-formylphenoxy)benzonitrile

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 Mar 2018 to 18 Apr 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

4-(4-bromo-3-formylphenoxy)benzonitrile

EC Number:

822-547-1

Cas Number:

906673-54-9

Molecular formula:

C14H8BrNO2

IUPAC Name:

4-(4-bromo-3-formylphenoxy)benzonitrile

Test material form:

solid: particulate/powder

Details on test material:

Off-white powder

Specific details on test material used for the study:

Purity/Composition: 98.7% Test substance storage: At room temperature protected from light Stable under storage conditions until: 20 November 2019 (retest date) (taken from label)

Test animals

Species:

rat

Strain:

other: WI(Han)

Details on species / strain selection:

The Wistar Han rat was chosen as the animal model for this study as it is an accepted rodent species for preclinical toxicity testing by regulatory agencies.

Sex:

female

Details on test animals or test system and environmental conditions:

Species: Rat Strain: Crl: WI(Han) Condition: Outbred, SPF-Quality Source: Charles River Deutschland, Sulzfeld, Germany. Number of Males: 12 Number of Females: 12 Target Age at the Initiation of Dosing: Approximately 9 weeks Target Weight at the Initiation of Dosing: 100 to 300 g (males) / 100 to 200 g (females)

Environmental Acclimation
The animals will be allowed to acclimate to the Test Facility toxicology accommodation for at least 5 days before the commencement of dosing.

Selection, Assignment, Replacement, and Disposition of Animals
Animals will be assigned to groups by a stratified randomization scheme designed to achieve similar group mean body weights. Males and females will be randomized separately. Animals in poor health or at extremes of body weight range will not be assigned to groups. Before the initiation of dosing, a health inspection will be performed and any assigned animals considered unsuitable for use in the study will be replaced by alternate animals obtained from the same shipment and maintained under the same environmental conditions. After initiation of dosing, study animals may be replaced during the replacement period with alternate animals in the event of accidental injury, non-test item-related health issues, or similar circumstances. The alternate animals may be used as replacements at the discretion of the Study Director. The disposition of all animals will be documented in the study records.

Housing
On arrival and following randomization, animals will be group housed (up to 3 animals of the same sex and same dosing group together) in polycarbonate cages (Makrolon type IV, height 18 cm) containing appropriate bedding (Lignocel S 8-15, JRS - J.Rettenmaier & Söhne GmbH + CO. KG, Rosenberg, Germany) equipped with water bottles. These housing conditions will be maintained unless deemed inappropriate by the Study Director and/or Clinical Veterinarian. The room(s) in which the animals will be kept will be documented in the study records. Animals will be separated during designated procedures/activities. Each cage will be clearly labeled with a color-coded cage card indicating test facility study no., group, animal number(s), and sex.

Environmental Conditions
The target conditions for animal room environment will be as follows: Temperature: 18 to 24°C Humidity: 40 to 70%
Light Cycle: 12-hours light and 12-hours dark (except during designated procedures) Ventilation: At least 10 air changes per hour Any variations to these conditions will be evaluated and maintained in the raw data.

Food
Pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany) will be provided ad libitum throughout the study, except during designated procedures. The feed is analyzed by the supplier for nutritional components and environmental contaminants. Results of the analysis are provided by the supplier and are on file at the Test Facility. It is considered that there are no known contaminants in the feed that would interfere with the objectives of the study.

Water
Municipal tap water will be freely available to each animal via water bottles. Periodic analysis of the water is performed, and results of these analyses are on file at the Test Facility. It is considered that there are no known contaminants in the water that would interfere with the objectives of the study.

Animal Enrichment
For psychological/environmental enrichment, animals will be provided with paper (Enviro-dri, Wm. Lilico & Son (Wonham Mill Ltd), Surrey, United Kingdom), except when interrupted by study procedures/activities.

Administration / exposure

Route of administration:

oral: gavage

Details on route of administration:

The test item and vehicle will be administered to the appropriate animals by once daily oral gavage for 7 days. Animals will be dosed approximately at the same time each day with a maximum of 6 hours difference between the earliest and latest dose. The dose volume for each animal will be based on the most recent body weight measurement. The doses will be given using a plastic feeding tube. The first day of dosing will be designated as Day 1 (exception: alternate animals used for replacement after Day 1 will assume the day of the animal being replaced). The dosing formulations will be stirred continuously during dose administration. A dose control system will be used as additional check to verify the dosing procedure according to Standard Operating Procedures.

Vehicle:

propylene glycol

Details on oral exposure:

A trial preparation representative of the dosing concentrations may be carried out prior to the start of the study to assess the suitability of the formulation procedure. Trial preparation formulations will not be used for dosing and will be discarded after the assessment is complete. Test item dosing formulations (w/w) will be homogenized to visually acceptable levels at appropriate concentrations to meet dose level requirements. The dosing formulations will be prepared daily and dosed within 4 hours after adding vehicle to the test item. Test item dosing formulations will be kept at room temperature until dosing. If practically possible, the dosing formulations and vehicle will be continuously stirred until and during dosing. Any residual volumes will be discarded unless otherwise requested by the Study Director.

Vehicle
Identification Propylene glycol Specific gravity 1.036

The test item and vehicle will be administered to the appropriate animals by once daily oral gavage for 7 days. Animals will be dosed approximately at the same time each day with a maximum of 6 hours difference between the earliest and latest dose. The dose volume for each animal will be based on the most recent body weight measurement. The doses will be given using a plastic feeding tube. The first day of dosing will be designated as Day 1 (exception: alternate animals used for replacement after Day 1 will assume the day of the animal being replaced). The dosing formulations will be stirred continuously during dose administration. A dose control system will be used as additional check to verify the dosing procedure according to Standard Operating Procedures.

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

7 days

Frequency of treatment:

once daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

150 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

3 sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

Male and female rats, approximately9weeks of age(for exact details see main study report) on treatmentDay 1,were administered PF-06932437via oral gavage dailyfor 7 consecutive days.

Positive control:

Not specified

Examinations

Observations and examinations performed and frequency:

Mortality/Moribundity Checks
Throughout the study, animals were observed for general health/mortality and moribundity twice daily, in the morning and at the end of the working day. Animals were not removed from cage during observation, unless necessary for identification or confirmation of possible findings.

Cage Side Observations
Cage side observations were performed once daily, immediately after dosing up to 30 minutes after dosing, throughout the dosing period. Animals were not removed from the cage during observation, unless necessary for identification or confirmation of possible findings.

Detailed Clinical Observations
The animals were removed from the cage, and a detailed clinical observation was performed on Day 1 and on Day 8.

Body Weights
Animals were weighed individually on Days 1, 4 and 7 (prior to dosing). A fasted weight was recorded on the day of necropsy.

Food Consumption
Food consumption was quantitatively measured weekly starting on Days 1-4 and 4-7.

Water Consumption
Subjective appraisal was maintained during the study, but no quantitative investigation introduced as no effect was suspected.

Sacrifice and pathology:

Animals surviving until scheduled euthanasia were weighed, euthanized using isoflurane, blood was sampled from the retro-orbital sinus (for clinical pathology)followed by exsanguination. Animals were fasted (overnight with a maximum of 24 hours) before their scheduled necropsy.

Animals were subjected to a complete necropsy examination, which included evaluation of the carcass and musculoskeletal system; all external surfaces and orifices; cranial cavity and external surfaces of the brain; and thoracic, abdominal, and pelvic cavities with their associated organs and tissues. Necropsy procedures were performed by qualified personnel with appropriate training and experience in animal anatomy and gross pathology. A veterinary pathologist, or other suitably qualified person, was available.

Other examinations:

Organ Weights
The organs identified in the following table were weighed at necropsy for all scheduled euthanasia animals. Paired organs were weighed together. Organs were weighed before fixation. Organ to body weight ratio/percentage (usingthe terminal body weight) was calculated.

Statistics:

Descriptive statistics number, mean and standard deviation will be reported whenever possible. Values may also be expressed as a percentage of predose or control values when deemed appropriate.

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No toxicologically relevantclinical signs were noted. Abnormal breathing was observed in one male treated at 1000 mg/kg at Days 2 and 3. Based on the incidence and duration, this was considered to be not toxicologically relevant. The observed scab observed in one male animal treated at 300 mg/kg occurred within the range of background findings to be expected for rats of this age and strain which are housed and treated under the conditions in this studyand did not show any apparent dose-related trend. At the incidence observed, these were considered to be unrelated to treatment.

Mortality:

no mortality observed

Description (incidence):

No mortality occurred during the study period.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Body weights and body weight gain of treated animals remained in the same range as controls over the study period.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

No toxicologically relevant changes in food consumption were noted in treated male animals. Slightly lower food consumptionfrom Day 1-4was noted in female animals treated at 300 mg/kg and 1000 mg/kg. As this change was not apparent from Day 4-7, this was considered not toxicologically relevant.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Hematological parameters of treated rats were considered not to have been affected by treatment. It should be noted that a low reticulocytes count was noted for Male No. 8 (treated at 300mg/kg). Based on the low incidence and absence of corroborative findings in the opposite sex, this was considered to be of no toxicological significance. Any changes in hematology parameters were considered to have arisen as a result of slightly high control values,slightly high or low individual valuesand/orin the absence of a treatment-related distribution, a minimal magnitude of the changeor corroborative findings in the opposite sex, considered to be of no toxicological significance.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

There were no differences noted in clinical chemistry parameters between control and treated rats that were considered toxicologically relevant. It should be noted that a high alanine and aspartate aminotransferase activity was noted for Female No. 24 (treated at 1000 mg/kg). Based on the low incidence and absence of corroborative findings in the opposite sex, this was considered to be of no toxicological significance. Any changes in clinical chemistry parameters were considered to have arisen as a result of slightly high or low control values, and/or in the absence of a treatment-related distribution, a minimal magnitude of the change or corroborative findings in the opposite sex, considered to be of no toxicological significance.

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Higher liver weight was noted at all dose levels, in both sexes, in a dose dependent fashion. This correlated to microscopic hypertrophy at 1000 mg/kg. In females, lower thymus weight wasnoted at 300 and 1000 mg/kg. There was no microscopic correlate. Higher adrenal gland weights were noted in females at 300 and 1000 mg/kg. There was no microscopic correlate. Higher kidney weights were noted in males at 1000 mg/kg. This may correlate with microscopic hyaline droplet accumulation. There were no other test item-related organ weight changes. Any other differences were considered not to be test item-related due to the direction of the change, lack of dose-related pattern, and/or general overlap and variability in individual values.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no test item-related gross observations. All of the recorded macroscopic findings were within the range of background gross observations encountered in rats of this age and strain.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The brain, thymus, adrenal glands, heart, liver, spleen, kidneys, stomach, testes and epididymides (males), and ovaries, uterus, cervix and vagina (females) were examined histologically.

Test item-related microscopic findings after treatment with PF-06932437were noted in the liver of the males starting at 150 mg/kg and females at 1000 mg/kgand in the kidney of males at 1000 mg/kg. Liver: Centrilobular hypertrophy was noted in the liver of males and females at 1000 mg/kg (minimal to mild) and in males at 150 and 300 mg/kg. This correlated to higher liver weights.

Kidney: In males only, there was an increased incidence and severity (minimal to mild) of hyaline droplet accumulation (3/3 males) in the kidney at 1000 mg/kg. The low incidence and severity of this common background finding in the male rat at 150 and 300 mg/kg was interpreted as not likely to be related to the test item. There were no other test item-related histologic changes. Remaining histologic changes were considered to be incidental findings. There was no test item-related alteration in the prevalence, severity, or histologic character of those incidental tissue alterations. Mild erosion or ulceration was noted in the stomach of 1 female at 1000 mg/kgand 1 male at 300mg/kg. Considering the low incidence this is likely a spontaneous or procedural (gavage) related change but a relationship to treatment cannot be completely excluded.

Histopathological findings: neoplastic:

not examined

Effect levels

Dose descriptor:

NOAEL

Effect level:

ca. 1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

clinical signs

food consumption and compound intake

gross pathology

histopathology: non-neoplastic

mortality

organ weights and organ / body weight ratios

Remarks on result:

other:

Remarks:

No toxicologically significant changes were noted in any of the remainingparameters investigated in this study(i.e.clinical appearance, body weight, food consumption, clinical laboratory investigationsand macroscopic examination). In conclusion, administration of PF-06932437 by once daily oral gavage was well tolerated in rats at levels of 1000 mg/kg. Based on these results, the no-observed-adverse-effect level (NOAEL) was considered to be 1000 mg/kg.

Target system / organ toxicity

Critical effects observed:

no

Lowest effective dose / conc.:

1 000 mg/kg bw/day (nominal)

Organ:

kidney

liver

Applicant's summary and conclusion

Conclusions:

In conclusion, administration of PF-06932437 by once daily oral gavage was well tolerated in rats at levels of 1000 mg/kg. Based on these results, the no-observed-adverse-effect level (NOAEL) was considered to be 1000 mg/kg.

Executive summary:

The objective of this study was to determine the potential toxicity of PF-06932437, when given orally by gavage for 7daysto Wistar rats. In addition,a No Observed Adverse Effect Level (NOAEL) was evaluated.

The following parameters and end points were evaluated in this study:  clinical signs, body weights, food consumption, clinical pathology parameters (hematology, coagulation, clinical chemistry), gross necropsy findings, organ weights, and histopathologic examinations. Test item-related higher liver weights were observed in malesand femalesstarting at 150 mg/kg, which correlated with microscopic centrilobular hypertrophy in both sexes at 1000 mg/kg.  Centrilobular hypertrophy and the liver weight increase wasinterpreted as nonadverse based on the low severity, absence of degeneration or necrosis and absence of significant changed serum liver enzymes. Test item-related higher adrenal and lower thymus weights were observed in females at 300 and 1000 mg/kg, which were considered non-adverse due to the lack of histologic correlation and low magnitude of the change. Accumulation of hyaline droplets was observed in the kidney of males at 1000 mg/kg.  This is a common spontaneous background change, however this wasnot noted in the concurrent controls and treatment with the test item may be associated with an increased incidence/severity of this change.  The increased kidney weights noted at males at 1000 mg/kg may correlate with this histological finding.  The accumulation of hyaline droplets and the increased kidney weight were considered non-adverse based on the low severity. No toxicologically significant changes were noted in any of the remainingparameters investigated in this study(i.e.clinical appearance, body weight, food consumption, clinical laboratory investigationsand macroscopic examination). In conclusion, administration of PF-06932437 by once daily oral gavage was well tolerated in rats at levels of 1000 mg/kg. Based on these results, the no-observed-adverse-effect level (NOAEL) was considered to be 1000 mg/kg.