2-Chloro-8-((S)-1-cyclopropyl-ethyl)-6-[(5-methanesulfonyl-pyridin-2-ylmethyl)-amino]-8Hpteridin-7-one

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 October 2016 - 16 November 2016

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2-chloro-8-[(1S)-1-cyclopropylethyl]-6-{[(5-methanesulfonylpyridin-2-yl)methyl]amino}-7,8-dihydropteridin-7-one

EC Number:

825-281-4

Cas Number:

1817775-66-8

Molecular formula:

C18H19ClN6O3S

IUPAC Name:

2-chloro-8-[(1S)-1-cyclopropylethyl]-6-{[(5-methanesulfonylpyridin-2-yl)methyl]amino}-7,8-dihydropteridin-7-one

Method

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S-9 mix

Test concentrations with justification for top dose:

Experiment 1: concentrations of BI 740293 at 4, 12.8, 40, 128, 400, 1280 and
4000 μg/plate. Experiment 2 the maximum test concentration was reduced to 800 μg/plate based on precipitation observed in Experiment . Narrowed concentration intervals were
employed covering the range 12.5-800 μg/plate.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

Controls

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

9-aminoacridine

2-nitrofluorene

sodium azide

benzo(a)pyrene

other: 2-aminoanthracene (AAN)

Details on test system and experimental conditions:

The test system was suitably labelled to clearly identify the study number, bacterial strain,
test article concentration (where appropriate), positive and vehicle controls, absence or
presence of S-9 mix.

Rationale for test conditions:

The assay was to be considered valid if the following criteria were met:
1. The vehicle control counts fell within the laboratory’s historical control ranges as defined
in Section 6.2
2. The positive control chemicals induced increases in revertant numbers of ≥2-fold (in
strains TA98, TA100 and WP2 uvrA pKM101) or ≥3-fold (in strains TA1535 and
TA1537) the concurrent vehicle control confirming discrimination between different
strains, and an active S-9 preparation
3. At least five analysable concentrations of the test article were available.

Evaluation criteria:

For valid data, the test article was considered to be mutagenic if:
1. A concentration related increase in revertant numbers was ≥2-fold (in strains TA98,
TA100 or WP2 uvrA pKM101) or ≥3-fold (in strains TA1535 or TA1537) the concurrent
vehicle control values
2. Any observed response was reproducible.
The test article was considered positive in this assay if all of the above criteria were met.
The test article was considered negative in this assay if none of the above criteria were met.

Statistics:

Individual plate counts were recorded separately and the mean and standard deviation of the
plate counts for each treatment were determined. Control counts were compared with the
laboratory’s historical control ranges (Section 6.2 and Section 6.3). Data were considered
acceptable if the vehicle control counts fell within the calculated historical control ranges and
the positive control plate counts were comparable with the historical control ranges.
The presence or otherwise of a concentration response was checked by non-statistical
analysis, up to limiting levels (for example toxicity, precipitation or 5000 μg/plate).
However, adequate interpretation of biological relevance was of critical importance.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

E. coli WP2 uvr A pKM 101

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

It was concluded that BI 740293 did not induce mutation in four histidine-requiring strains
(TA98, TA100, TA1535 and TA1537) of Salmonella typhimurium, and one
tryptophan-requiring strain (WP2 uvrA pKM101) of Escherichia coli when tested under the
conditions of this study. These conditions included treatments at concentrations up to at least
800 μg/plate (a precipitating concentration), in the absence and in the presence of a rat liver
metabolic activation system (S-9) using plate incorporation and pre-incubation treatment
methodologies.