2-Pyridinecarboxamide, 4-[4-[[[[4-chloro-3-(trifluoromethyl)phenyl]amino]carbonyl]amino]phenoxy]-N-methyl-

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Salmonella/microsome test (Ames screening test; strains TA1535, TA1537, TA 98, TA100, TA102): negative (+/- S9 mix)

 

Salmonella/microsome test (Ames test; strains TA 98, TA 100, TA 102, TA 1535 and TA 1537): negative (+/- S9 mix); read-across from BAY 54-9085

 

chromosome aberration (Chinese hamster V79 cells): positive with metabolic activation, negative without metabolic activation; read-across from BAY 54-9085

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Oct 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

yes

Remarks:

- screening version (only one plate per dose and strain investigated, purity of test item not specified)

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine gene locus

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced male rat liver S9 mix

Test concentrations with justification for top dose:

Plate incorporation test: 0, 16, 50, 160, 500, 1600, 5000 µg/plate
Independent preincubation test: 0, 1, 2, 4, 8, 16, 32 µg/plate

Vehicle / solvent:

DMSO

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: sodium azide (only TA 1535), nitrofurantoin (only TA 100), 4-nitro-1,2-phenylene diamine (TA 1537 and TA 98), cumene hydroperoxide (only TA 102), 2-aminoanthracene.

Remarks:

The positive controls sodium azide, nitrofurantoin, 4-nitro-1,2-phenylene diamine and cumene hydroperoxide were only used without S9 mix; the positive control 2-aminoanthracene was only used with S9 mix.

Details on test system and experimental conditions:

METHOD: Standard plate test and preincubation test; only one plate per dose and strain investigated

Evaluation criteria:

A reproducible and dose-related increase in mutant counts of at least one strain is considered to be a positive result. For TA 1535, TA 100 and TA 98 this increase should be about twice that of negative controls, whereas for TA 1537 at least a threefold increase should be reached. For TA 102 an increase of about 150 mutants should be reached. Otherwise, the result is evaluated as negative. However, these criteria may be overruled by good scientific judgment. In case of questionable results, investigations should continue, possibly with modifications, until a final evaluation is possible.

Statistics:

not specified

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

bacteriotoxic effects at all tested doses

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

bacteriotoxic effects at all tested doses

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

bacteriotoxic effects at all tested doses

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

bacteriotoxic effects at all tested doses

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

bacteriotoxic effects at all tested doses

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

The Ames test screening, employing doses of up to 5000 µg per plate, showed BAY 43-9006 to produce bacteriotoxic effects with all tested doses. Therefore, 32 µg per plate and above could not be used for assessment. Substance precipitation started at 1600 µg per plate.

Evaluation of individual dose groups, with respect to relevant assessment parameters (dose effect, reproducibility), revealed no biologically relevant variations from the respective negative controls. In spite of the low doses used, positive controls increased the mutant counts to well over those of the negative controls, and thus demonstrated the system's high sensitivity. Despite this sensitivity, no indications of mutagenic effects of BAY 43-9006 could be found at assessable doses of up to 16 µg per plate in any of the Salmonella typhimurium strains used.

Due to these results BAY 43-9006 has to be regarded as non-mutagenic.

Conclusions:

Interpretation of results: negative

Executive summary:

BAY 43-9006 was initially screened with one plate per dose using the Salmonella/microsome plate incorporation test for point mutagenic effects in assessable doses of up to and including 16 µg per plate on the Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 (similar to OECD TG 471). The independent repeat was performed as preincubation for 20 minutes at 37°C. Other conditions remained unchanged. All tested doses caused bacteriotoxic effects. Total bacteria counts were reduced and inhibition of growth was observed. Therefore, the used dose range could only be used to a limited extent up to and including 16 µg per plate for assessment purposes. Substance precipitation occurred at the dose 1600 µg per plate and above. Evidence of mutagenic activity of BAY 43-9006 was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.

 

Therefore, BAY 43-9006 was considered to be non-mutagenic without and with S9 mix in the plate incorporation as well as in the preincubation modification of the Salmonella/microsome test.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH

Regarding human health toxicity results from animal studies and human data are available for either sorafenib base or sorafenib tosylate to fulfill REACH requirements of Annex VIII (10-100 t/a). Sorafenib base (BAY 43-9006, CAS 284461-73-0) is the active ingredient of BAY 54-9085, the tosylate salt of sorafenib (CAS 475207-59-1). Under physiological conditions in solution a dissociation of the tosylate takes place and therefore an identical pharmacological and toxicological effect of sorafenib base (BAY 43-9006, CAS 284461-73-0) and sorafenib tosylate (BAY 54-9085, CAS 475207-59-1) is to be expected at slightly different doses, taking into account the conversion factor of 1.3705.
Under physiological conditions a dissociation of p-toluene sulfonic acid of sorafenib tosylate takes place releasing sorafenib as active ingredient into the body.
Therefore, an identical toxicity profile of sorafenib base (BAY 43-9006, CAS 284461-73-0) and sorafenib tosylate (BAY 54-9085, CAS 475207-59-1) is to be expected, taking into account the differences in molecular weight (conversion factor 1.3705).
A detailed justification for read-across is attached in iuclid section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine gene locus

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

strong, strain-specific bacteriotoxic effect at 16 µg/plate and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

strong, strain-specific bacteriotoxic effect at 16 µg/plate and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

strong, strain-specific bacteriotoxic effect at 16 µg/plate and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

strong, strain-specific bacteriotoxic effect at 16 µg/plate and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

strong, strain-specific bacteriotoxic effect at 16 µg/plate and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Executive summary:

For BAY 43-9006 (sorafenib base) only a Ames screening test is available. Therefore, an Ames test according to OECD TG 471 with BAY 54-9085 (tosylate salt of sorafenib) were additionally used. Under physiological conditions a dissociation of the salt takes place. Therefore, an identical toxicity profile of BAY 54-9085 and BAY 43-9006 is to be expected.

 

BAY 54-9085 was initially investigated using the Salmonella/microsome plate incorporation test for point mutagenic effects in doses of up to and including 5000 µg per plate on the Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 according to OECD TG 471. The independent repeat was performed as preincubation for 20 minutes at 37°C using doses of up to and including 64 µg per tube. Other conditions remained unchanged. Doses up to and including 8 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At higher doses, the substance had a strong, strain-specific bacteriotoxic effect, so that this range could only be used to a limited extent up to and including 64 µg per plate for assessment purposes. Substance precipitation occurred at the dose

5000 µg per plate. Evidence of mutagenic activity of BAY 54-9085 was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.

In this test, BAY 54-9085 was considered to be non-mutagenic without and with S9 mix in the plate incorporation as well as in the preincubation modification of the Salmonella/microsome test.

Based on read-across, the result is applied also to the target substance BAY 43-9006.

Reference 3

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH

Regarding human health toxicity results from animal studies and human data are available for either sorafenib base or sorafenib tosylate to fulfill REACH requirements of Annex VIII (10-100 t/a). Sorafenib base (BAY 43-9006, CAS 284461-73-0) is the active ingredient of BAY 54-9085, the tosylate salt of sorafenib (CAS 475207-59-1). Under physiological conditions in solution a dissociation of the tosylate takes place and therefore an identical pharmacological and toxicological effect of sorafenib base (BAY 43-9006, CAS 284461-73-0) and sorafenib tosylate (BAY 54-9085, CAS 475207-59-1) is to be expected at slightly different doses, taking into account the conversion factor of 1.3705.
Under physiological conditions a dissociation of p-toluene sulfonic acid of sorafenib tosylate takes place releasing sorafenib as active ingredient into the body.
Therefore, an identical toxicity profile of sorafenib base (BAY 43-9006, CAS 284461-73-0) and sorafenib tosylate (BAY 54-9085, CAS 475207-59-1) is to be expected, taking into account the differences in molecular weight (conversion factor 1.3705).
A detailed justification for read-across is attached in iuclid section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Details on mammalian cell type (if applicable):

- Type and identity of media: Eagle's minimal essential medium (MEM, Earle) containing 10 % fetal calf serum
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes

Metabolic activation:

with and without

Key result

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 20 µg/ml and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 10 µg/ml and above

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Executive summary:

For BAY 43-9006 (sorafenib base) no in vitro mammalian chromosome aberration data are available. Therefore, in vitro mammalian chromosome aberration data with BAY 54-9085 (tosylate salt of sorafenib) were used. Under physiological conditions a dissociation of the salt takes place. Therefore, an identical toxicity profile of BAY 54-9085 and BAY 43-9006 is to be expected.

The clastogenic potential of the test substance was evaluated in a chromosome aberration test on Chinese hamster V79 cells in the presence and absence of S9 mix according to OECD TG 473. Without S9 mix cytotoxic effects were observed at 10 µg/ml and above. With S9 mix cytotoxic effects were observed at 20 µg/ml and above. Precipitation of BAY 54-9085 in the medium was not observed. In the presence of S9 mix cultures treated with 40 µg/ml BAY 54-9085 showed biologically relevant and statistically significant increased numbers of aberrant metaphases. No clastogenic effects were observed without S9 mix. In this test, BAY 54-9085 is considered to be clastogenic for mammalian cells in vitro.

Based on read-across, the result is applied also to the target substance BAY 43-9006.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

Mouse micronucleus test (i.p., 125, 250 and 500 mg/kg bw): negative; read-across from BAY 54-9085

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH

Regarding human health toxicity results from animal studies and human data are available for either sorafenib base or sorafenib tosylate to fulfill REACH requirements of Annex VIII (10-100 t/a). Sorafenib base (BAY 43-9006, CAS 284461-73-0) is the active ingredient of BAY 54-9085, the tosylate salt of sorafenib (CAS 475207-59-1). Under physiological conditions in solution a dissociation of the tosylate takes place and therefore an identical pharmacological and toxicological effect of sorafenib base (BAY 43-9006, CAS 284461-73-0) and sorafenib tosylate (BAY 54-9085, CAS 475207-59-1) is to be expected at slightly different doses, taking into account the conversion factor of 1.3705.
Under physiological conditions a dissociation of p-toluene sulfonic acid of sorafenib tosylate takes place releasing sorafenib as active ingredient into the body.
Therefore, an identical toxicity profile of sorafenib base (BAY 43-9006, CAS 284461-73-0) and sorafenib tosylate (BAY 54-9085, CAS 475207-59-1) is to be expected, taking into account the differences in molecular weight (conversion factor 1.3705).
A detailed justification for read-across is attached in iuclid section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Type of assay:

micronucleus assay

Species:

mouse

Strain:

NMRI

Sex:

male

Route of administration:

intraperitoneal

Sex:

male

Genotoxicity:

negative

Toxicity:

yes

Remarks:

see "Additional information on results"

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

After two intraperitoneal administrations of 125, 250 and 500 mg/kg BAY 54-9085, treated males showed the following compound-related symptoms until sacrifice: apathy, roughened fur, hard abdomen, spasm, periodically stretching of body and difficulty in breathing. There was no substance-induced mortality. No symptoms were recorded for the control groups. No animals died in these groups.

There was no altered ratio between polychromatic and normochromatic erythrocytes.

After two intraperitoneal treatments of males with doses up to and including 500 mg/kg no indications of a clastogenic effect of BAY 54-9085 were found.

Cyclophosphamide, the positive control, had a clear clastogenic effect, as is shown by the biologically relevant increase in polychromatic erythrocytes with micronuclei. The ratio of polychromatic to normochromatic erythrocytes was not altered.

Table 1: Summary of results from micronucleus test with BAY 54-9085

Treatment group	Dose i.p. (mg/kg bw)	Number of evaluated PCE	Number of NCE per 2000 PCE	MNNCE per 2000 NCE	MNPCE per 2000 PCE
Negative control	0	10,000	1873± 427	3.2 ± 1.4	2.4 ± 1.1
BAY 54-9085	2 x 125	10,000	1017 ± 333	1.6 ± 1.5	2.8 ± 1.8
	2 x 250	10,000	902 ± 148	2.3 ± 0.4	2.4 ± 0.9
	2 x 500	10,000	1039 ± 304	0.8 ± 1.1	3.2 ± 1.5
Positive control  (Cyclophosphamide)	1 x 20	10,000	1638 ± 498	2.3 ± 2.5	32.2* ± 12.2

* p<0.01 in non-parametric Wilcoxon ranking test

 

NCE = normochromatic erythrocytes

PCE = polychromatic erythrocytes

MNNCE = micronucleated NCE

MNPCE = micronucleated PCE

 

Executive summary:

For BAY 43-9006 (sorafenib base) no in vivo genetic toxicity data are available. Therefore, data on a micronucleus test in mice with BAY 54-9085 (tosylate salt of sorafenib) were used. Under physiological conditions a dissociation of the salt takes place. Therefore, an identical toxicity profile of BAY 54-9085 and BAY 43-9006 is to be expected.

Male mice treated with BAY 54-9085 received two intraperitoneal administrations of 125, 250 and 500 mg/kg bw, respectively, separated by 24 hours. Males of the positive control received a single intraperitoneal treatment with 20 mg/kg cyclophosphamide. The femoral marrow of all groups was prepared, 24 hours after the last administration. Males treated twice with BAY 54-9085 in doses up to 500 mg/kg showed symptoms of toxicity after administration, starting at 125 mg/kg. However, all males survived until the end of the test. There was no altered ratio between polychromatic and normochromatic erythrocytes. After two intraperitoneal treatments of males with doses up to and including 500 mg/kg no indications of a clastogenic effect of BAY 54-9085 were found. In this test, BAY 54-9085 was concluded to be negative in the mouse micronucleus assay.

Based on read-across, the result is applied also to the target substance BAY 43-9006.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

The genotoxicity of sorafenib base was investigated in a bacterial mutagenicity screening test, whereas sorafenib tosylate was studied for indications of genotoxicity in bacteria, mammalian cells (chromosomal aberrations in vitro in Chinese hamster V79 cells), and in vivo (mouse micronucleus test in bone marrow). Under physiological conditions a dissociation of the salt takes place. Therefore, an identical toxicity profile of BAY 54-9085 and BAY 43-9006 is to be expected. A justification for read-across is attached to Iuclid section 13.

 

In vitro / in silico studies

BAY 43-9006 was initially screened with one plate per dose using the Salmonella/microsome plate incorporation test for point mutagenic effects in assessable doses of up to and including 16 µg per plate on the Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 (similar to OECD TG 471). The independent repeat was performed as preincubation for 20 minutes at 37°C. Other conditions remained unchanged. All tested doses caused bacteriotoxic effects. Total bacteria counts were reduced, and inhibition of growth was observed. Therefore, the used dose range could only be used to a limited extent up to and including 16 µg per plate for assessment purposes. Substance precipitation occurred at the dose 1600 µg per plate and above. Evidence of mutagenic activity of BAY 43-9006 was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.

The screening test showed no mutagenic but strong bacteriotoxic effects, thereby limiting the final assessment to the results of one concentration only for the substance (Herbold, 1998).

 

In addition, the bacterial gene mutation potential was assessed in an in silico prediction for sorafenib base based on DEREK and Leadscope. Both models predict BAY 43-9006 to be non-mutagenic in a bacterial reverse mutation assay (Wichard, 2021).

 

BAY 54-9085 was initially investigated using the Salmonella/microsome plate incorporation test for point mutagenic effects in doses of up to and including 5000 µg per plate on the Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 according to OECD TG 471. The independent repeat was performed as preincubation for 20 minutes at 37°C using doses of up to and including 64 µg per tube. Other conditions remained unchanged. Doses up to and including 8 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At higher doses, the substance had a strong, strain-specific bacteriotoxic effect, so that this range could only be used to a limited extent up to and including 64 µg per plate for assessment purposes. Substance precipitation occurred at the dose

5000 µg per plate. Evidence of mutagenic activity of BAY 54-9085 was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.

Therefore, BAY 54-9085 was considered to be non-mutagenic without and with S9 mix in the plate incorporation as well as in the preincubation modification of the Salmonella/microsome test (Herbold, 2000a).

 

The clastogenic potential of the test substance was evaluated in a chromosome aberration test on Chinese hamster V79 cells in the presence and absence of S9 mix according to OECD TG 473. Without S9 mix cytotoxic effects were observed at 10 µg/ml and above. With S9 mix cytotoxic effects were observed at 20 µg/ml and above. Precipitation of BAY 54-9085 in the medium was not observed. In the presence of S9 mix cultures treated with 40 µg/ml BAY 54-9085 showed biologically relevant and statistically significant increased numbers of aberrant metaphases. No clastogenic effects were observed without S9 mix. Based on the results of this test, BAY 54-9085 is considered to be clastogenic for mammalian cells in vitro (Herbold, 2000).

 

In vivo study

Male mice treated with BAY 54-9085 received two intraperitoneal administrations of 125, 250 and 500 mg/kg bw, respectively, separated by 24 hours. Males of the positive control received a single intraperitoneal treatment with 20 mg/kg cyclophosphamide. The femoral marrow of all groups was prepared, 24 hours after the last administration. Males treated twice with BAY 54-9085 in doses up to 500 mg/kg showed symptoms of toxicity after administration, starting at 125 mg/kg. However, all males survived until the end of the test. There was no altered ratio between polychromatic and normochromatic erythrocytes. After two intraperitoneal treatments of males with doses up to and including 500 mg/kg no indications of a clastogenic effect of BAY 54-9085 were found. Thus, BAY 54-9085 was concluded to be negative in the mouse micronucleus assay (Herbold, 2000c).

 

Studies for assessment of genetic toxicity of sorafenib-tosylate and -base

	Sorafenib tosylate (source)	Sorafenib base (target)
CAS No.	475207-59-1	284461-73-0
BAY No.	54-9085	43-9006
In silico Ames	-	·         In silico prediction by DEREK & Leadscope on mutagenicity in bacteria (Wichard, 2021) ·         Result: negative ·         Reliability 1
Ames (OECD TG 471) plate incorporation & preincubation method; with & without S9-mix	·         Report PH-29467, study no. T 7068427 (Herbold, 2000) ·         GLP, guideline study ·         No deviations ·         Compound: batch 990722, purity 97.1% ·         Formulation: DMSO; final suspensions freshly prepared ·         Strains: TA1535, TA1537, TA 98, TA100, TA102 ·         Seven concentrations tested in repeated preincubation test (due to bateriotoxic effects in first test) ·         Appropriate controls used ·         Results: non-mutagenic (no relevant increase of mutants, no dose-effect) ·         Reliability 1	·         Report PH-28141, study no. T 0059899 (Herbold, 1998) ·         Screening test; non-GLP, equivalent to OECD TG 471 ·         Plate incorporation ·         Compound: batch 52821-61-1 purity not indicated ·         Formulation: DMSO; final suspensions freshly prepared ·         Strains: TA1535, TA1537, TA 98, TA100, TA102 ·         Six concentrations up to 5 mg/plate tested ·         Appropriate controls used ·         Results: strong bacteriotoxic effects; limited dose (16 µg/ plate) for evaluation -> non-mutagenic ·         Reliability 2   Read-across in addition
Chrom.Abb. in vitro (OECD TG 473)	·         Report PH-29598, study no. 8068851 (Herbold, 2000) ·         GLP, guideline study; no deviations ·         Compound: Batch 990722; purity 97.1% ·         Formulation in DMSO (stability tested) ·         Cells: Chinese hamster V79 ·         Six concentrations up to 80µg/ml tested (pre-experiment performed) ·         Appropriate controls used ·         Results: cytotoxic effects observed; biologically relevant & statistically significant increased no. of aberrant metaphases with S9 mix -> clastogenic ·          Reliability 1	No data Read-Across
MNT in vivo (OECD TG 474)	·         Report PH-29474, study no. T 9068429 (Herbold, 2000) ·         GLP, OECD 474 guideline study; no deviations ·         Mice, 2x i.p., 3 dose-groups ·         Compound: batch 990722; purity 97.1%; homogenicity & stability tested ·         Formulation in 0.5% aqueous Cremophor (as suspension) ·         Cyclophosphamid as positive control ·         Evaluation of micronuclei in bone marrow erythroblasts ·         Results: no clastogenic effect (up to 500 mg/kg) ·         Reliability 1	No data Read-Across

 

In summary, sorafenib tosylate (as source for read-across) exhibited no genotoxic properties in bacteria (experimental and in silico Ames) but in mammalian cells (V79; MNT) in vitro. A subsequent in vivo micronucleus test in mice (OECD TG 474) was negative.

According to the current REACH mutagenicity testing strategy a second in vivo test (here for testing gene mutation in vivo) needs only to be performed if required for a conclusion.

For sorafenib tosylate or base, a second in vivo test is not considered to provide further useful information since a conclusion on carcinogenicity as the predominant resulting risk associated with human exposure to mutagenic substances can be drawn based on existing carcinogenicity studies. Two carcinogenicity studies (in rats and mice) clearly demonstrated no carcinogenic effect by sorafenib tosylate after a 2-years period of dietary treatment.

 

Based on these considerations a mutagenic potential is not concluded for sorafenib base and a classification according to Regulation (EU) No. 1272/2008 (CLP) is not justified.

Justification for classification or non-classification

Based on the study results a classification according to Regulation (EC) No.1272/2008 (CLP) is not required.