3-bromo-5-fluoro-1-[(4-methylphenyl)sulfonyl]-1H-pyrrolo[2,3-b]pyridine

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-10-05 to 2016-11-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

Paris, July 2010

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

Official Journal of the European Union No. L142, May 2008, including most recent amendments

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

March 2003

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

3-bromo-5-fluoro-1-(4-methylbenzenesulfonyl)-1H-pyrrolo[2,3-b]pyridine

Cas Number:

1417421-99-8

Molecular formula:

C14H10BrFN2O2S

IUPAC Name:

3-bromo-5-fluoro-1-(4-methylbenzenesulfonyl)-1H-pyrrolo[2,3-b]pyridine

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: I15ID3592
- Expiration date of the lot/batch: 21 September 2017 (expiry date)
- Purity/composition correction factor: 1
- Purity: 99.1% w/w - UPLC

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/vehicle: There was no information available regarding the solubility or stability in vehicle.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing:
The test item preparations (w/w) were prepared within 4 hours prior to each dosing. Homogeneity was assessed by visual inspection of the solutions. For the test item preparations of the pre-screen test only, in order to obtain homogeneity, the test item (preparations) were heated in a water bath with a maximum temperature of 61.4 ºC for a maximum of 30 minutes. The test item (preparations) were allowed to cool to a temperature of maximally 40 ºC prior to dosing. Correction of the purity/composition of the test item was not applicable, since the test method required a logical concentration range rather than specific dose levels to be dosed.

In vivo test system

Test animals

Species:

mouse

Strain:

CBA:J

Remarks:

inbred, SPF-quality

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: CBA/J, inbred, SPF-Quality; Janvier, Le Genest-Saint-Isle, France.
- Age at study initiation: Approximately 10 weeks old
- Weight at study initiation: 19.7 - 24.4 grams
- Housing: Group housed in labeled Makrolon cages (MIII type; height 18 cm) containing sterilised sawdust as bedding material (Lignocel S 8-15, JRS - J.Rettenmaier & Söhne GmbH + CO. KG, Rosenberg, Germany). Paper (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) and shelters (disposable paper corner home, MCORN 404, Datesand Ltd, USA) were supplied as cage-enrichment. On Day 6 of the main study, the animals were group housed in Makrolon MII type cages with a sheet of paper instead of sawdust and cage enrichment.
- Diet (e.g. ad libitum): ad libitum, pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany)
- Water (e.g. ad libitum): ad libitum, tap water
- Acclimation period: At least 5 days before the start of treatment under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (deg C): 18 to 24°C
- Humidity (%): 40 to 70%
- Air changes (per hr): At least 10 air changes/hour
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark

Study design: in vivo (LLNA)

Vehicle:

propylene glycol

Concentration:

PreScreen Test: 25% and 40% w/w (highest concentration that could be prepared homogeneously)
Main Study: 0, 2%, 10%, 25% w/w

No. of animals per dose:

Five females per group; 4 groups (including control group)

Details on study design:

Rationale vehicle selection:
The vehicle was selected on the basis of maximizing the solubility using the test item data provided by the Sponsor
and trial preparation results performed at Charles River Den Bosch. The vehicle was chosen from the vehicles specified in the test guideline: Acetone/Olive oil (4:1 v/v) (test item did not dissolve), N,N-dimethylformamide (test item did not dissolve), methylethylketone (test item did not dissolve), propylene glycol (turbid solution) and dimethylsulfoxide.

PRE-SCREEN TESTS:
- Compound solubility: no data
- Irritation: Very slight to well-defined erythema was noted for all animals between Days 1 and 3. White test item remnants were present on the dorsal surface of the ears of all animals between Days 1 and 3, which did not hamper scoring of the skin reactions.
- Systemic toxicity: Hunched posture and piloerection were noted for both animals treated at a concentration of 40% on Days 2 and 3.
- Ear thickness measurements: Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values. Based on the tolerability of the test item, the highest test item concentration selected for the main study was a 25% concentration.

MAIN STUDY
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response:
If the results indicate a SI ≥ 3, the test item may be regarded as a skin sensitizer. The results were evaluated according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2015) (including all amendments) and the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, including all amendments. Consideration was given to the EC3 value (the estimated test item concentration that will give a SI =3).

Classification of results:
SI value UN-GHS 2015; EC-CLP 2008 EC Hazard statement
SI < 3 No sensitizer -
SI ≥ 3 Cat 1 Skin sensitizer H317: May cause an allergic skinreaction
EC3 value ≤ 2%: sub-category 1A
EC3 value > 2%: sub-category 1B

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

No data

Results and discussion

Positive control results:

At concentrations 5%, 10% and 25% SI values of the positive control item were 1.4, 1.5 and 4.3 respectively. An EC3 value of 18.0% was calculated using linear interpolation.
The calculated EC3 value was in the accepable range of 4.8 and 19.5%. The results of the 6 monthly reliability checks of the recent years were 16.5, 14.5, 13.4, 14.1, 17.3 and 9.8%
Based on the results, it was concluded that the Local Lymph Node Assay as performed in the laboratory is an appropriate model for testing contact hypersensitivity.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

0.9

Variability:

+/- 0.2

Test group / Remarks:

Based on 5 animals in 2% w/w in propylene glycol group

Results 2

Parameter:

SI

Value:

1.1

Variability:

+/- 0.2

Test group / Remarks:

Based on 5 animals in 10% w/w in propylene glycol group

Results 3

Parameter:

SI

Value:

1.1

Variability:

+/- 0.3

Test group / Remarks:

Based on 5 animals in 25% w/w in propylene glycol group

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA:
mean DPM ± SEM:
0% w/w group: mean DPM ± SEM: 860 ± 151
2% w/w group: mean DPM ± SEM: 760 ± 98
10% w/w group: mean DPM ± SEM: 968 ± 116
25 %w/w group: mean DPM ± SEM: 984 ± 130
SEM = Standard Error of the Mean

EC3 CALCULATION
The EC3 value (the estimated test item concentration that will give a SI =3) exceeds 25%.

CLINICAL OBSERVATIONS:
- Skin reactions/irritation: No erythema of the ears was observed in any of the animals examined. White test item remnants were present on the dorsal surface of the ears of the experimental animals throughout the observation period, which did not hamper scoring of the skin reactions.
- Systemic toxicity: No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study.
- Macroscopy of the auricular lymph nodes and surrounding area: All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals.

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

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Since there was no indication that the test item elicits a SI ≥ 3 when tested up to 25%, T003685 was not considered to be a skin sensitizer. It was established that the EC3 value (the estimated test item concentration that will give a SI =3) (if any) exceeds 25%.

Based on these results, T003685 was not regarded as a skin sensitizer according to the recommendations made in the test guidelines. The test item does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2015) (including all amendments) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures (including all amendments).