Boronic acid, B-(2-fluoro-3-methoxyphenyl)-

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Based on the results from the Ames test there was a positive indication of genetic toxicity. Based on the results from the chromosome aberration test there was no indication of genetic toxicity.

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:

14 September - 17 September 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

The test material was stored at room temperature and kept in a closed container when not in use

Species / strain / cell type:

other: TA 97a, TA 98, TA 100, TA 102, TA 1535

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced rat liver S9 prepared in-house was used as the metabolic activation system.

Test concentrations with justification for top dose:

Six dose levels were designed using an approximate spacing factor of 3 in the first experiement: 15, 50, 150, 500, 1,500, and 5,000 μg/plate with and without S9 mix.

Vehicle / solvent:

Dimethyl sulfoxide (DMSO)

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

sodium azide

other: Dexon, 2-Aminofluorene, 1,8-Dihydroxyanthraquinone, 2-Aminoanthracene

Details on test system and experimental conditions:

Preliminary Test:
A preliminary test for the Bacterial Reverse Mutation Test of FMPBA was performed in the lab. In the test, according to the results of the test item solubility,
DMSO was used as solvent. The standard plate incorporation method was performed at 3 dose levels with 5 intervals between test point, including 5000,
1000 and 200 µg/plate, in 5 tester strains of: TA97a, TA98, TA100, TA102 and TA1535, only without metabolic activation system. Solvent controls (DMSO) in each tester strain were performed at the same time. The dose volume of each dose group and solvent control group were 0.1ml/plate, in duplicate.

Preliminary test results:
About the precipitate of the test item, Monitoring of TA98 showed that there were precipitates at 5000 µg/plate dose level before and after the incubation, but the precipitates did not affect the observation of the background lawn. Moreover, no cytotoxicity was found at all designed dose level in all tester strains.

Dose Selection:
Dose selection is performed based on the results of the preliminary test and the related requirements of PRC.iMEP the Guidelines for Testing of Chemicals (Health Effect, second edition), 471 (2013). Six dose, levels were designed using an approximate spacing factor of 3 in the first experiment, including 5000, 1500, 500, 150, 50 and 15 µg/plate without and with S9mix. Solvent· controls (DMSO) and positive controls in each tester strain were performed at the same time.

Preparation of the test item:
In the experiment DMSO was used as a solvent. Two test items (0.30129g and 0.09051g) were weighed and transfered into calibrated aseptic tubes. 6,000 mL DMSO were added into the tube and mixed thoroughly to the calibrated volume to obtain 50 and 15 mg/mL working solution. Under aseptic condition, the working solution of other concentrations were diluted using the spacing factors of 10. In this study, the test item was prepared just before being applied to the test system.

Enrichment culture:
One day prior to the plate-incorporation, the stored tester strains were thawed and 100 µl of bacterial suspension was cultivated in nutrient broth medium for approximately 16 hours at 37.1-38.1°C.

Viable count:
In order to confum the density of living bacteria in the cultures, some. cultures were taken out for the viable count. The cultures were diluted with sterile water, then
200 µ1 of the dilution of bacteria cultures that had been diluted by a factor of 10^5, 10^6, or 10^7 respectively, 100µ1 of histidine solution supplemented with an excess of
histidine (0.5% L-histidine solution), 100µ1 of 0.01 % d-biotin solution,500 µ1 of PBS and 2000 µl of molten top-layer agar medium kept in a water bath at 45.1-46.8 °C were
added to a sterile tube under aseptic conditions. After vortexing, the mixture was evenly overlaid on the surface of the MGA plate, and each of the above diluted concentrations wereperformed in triplicate. When solidified, the plates were inverted and incubated for about 64 hours at 35.2-37.6°C. Then the number of the colonies in plate with the 10^6 -fold dilutions was counted. The density of viable bacteria in the cultures was calculated based on the mean number of colonies and dilution factor.

Plate-incorporation:
In the absence of S9 mix: 200 µl of histidine-biotin solution,100 µl of bacteria culture, 500 µl of PBS, 100 µl of the test item formulation or DMSO or positive control solution and 2000 µl of molten top-layer agar mediumkept in a water bath at 44.5-46. 7°C were added to a sterile test tube under aseptic conditions. After vortexing, the mixture was evenly overlaid on the surface of MGA plate, all dose levels and the controls were performed in triplicate. After the top-layer agar, was solidified, the plates were inverted and incubated for about 48 hours at 36.3-38.2°C. The test item precipitation was observed by naked Dyes in three parallel plates of each dose group of TA98 before and after incubation. After incubation, the numberof revertant colonies in each plate were counted. As counting the plates of the positive controls (except for TA1535), the back ofa plate was divided into eight sectorson back, and two diagonal parts were chosen randomly and counted, then the result was multiplied by 4 as the number of revertant colonies, and the signs of background lawn were observed microscopically .
In the presence of S9 mix: All procedures were the same as those in the absence of S9 mix except for fBS replaced with S9 mix.

Evaluation criteria:

Criteria of positive result:
When, there is a concentration-related increase over the range (two times equal to or greater than the concurrent solvent control in TA97a, TA98, TA100, TA102 and three times equal to or greater than the concurrent solvent control in TA 1535) in the mean number of revertant colonies in at least one strain with or without metabolic activation system, the test item should be evaluated as positive.

When there is a reproducible increase (two times equal to or greater than the concurrent solvent control in TA97a, TA98, TA100, TA102 and three times equal to or greater than the concurrent solvent control in TA 1535) at one or more concentrations in the mean number of revertant colonies in at least one strain with or without metabolic activation system, the test item should be evaluated as positive.

Criteria of negative result:
The test item should be evaluated as negative if none of the above criteria are met.

Criteria of equivocal result:
Although most tests give clear positive or negative results, in some instances the data generated prohibit making a definite judgment about test item. Results of this type should be reported as equivocal.

Statistics:

For three plates at each dose and control group, the mean number and the standard deviation of the number of revertant.colonies were calculated: in Excel (2017). At the same time, the ratio of the mean number of revertant colonies between each group and the concurrent solvent control was calculated.

Species / strain:

S. typhimurium TA 97

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Test Item Precipitate: There were precipitates at 5,000 µg/plate dose levels on the MGA plates, before and after the incubation, with and without metabolic activation system.

Cytotoxicity: No cytotoxicity was found at any of the designed dose levels in any of the tester strains in the two treated conditions.

All the results of the positive and solvent controls met the requirements of the tests, so the sensitivity of the test and the efficacy of the S9 mix were validated.

Conclusions:

Under the conditions of this study, the results were positive. Therefore, the test item is considered to be mutagenic in the bacterial reverse mutation assay using histidine requiring tester strains of Salmonella typhimurium.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

19 September - 22 October, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosomal Aberration Test)

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

Chinese hamster lung (CHL/IU)

Details on mammalian cell type (if applicable):

From ATCC®CRL-1935

Metabolic activation:

with and without

Metabolic activation system:

In this study, rat liver S9 prepared in-house was used as the metabolic activation system. The S9 was prepared from the livers of the rats induced with Aroclor1254.

Test concentrations with justification for top dose:

Dose selection was determined based on the results of the preliminary test, and SEPA Guidelines for Testing of Chemicals. The test was conducted respectively in three treatment conditions of exposure for 3 hours with and without metabolic activation, and exposure for 24 hours without metabolic activation. Six doses of 5000, 1667, 555, 185, 61.7 and 20.6 µg/ml were included in each treatment condition along with the concurrent solvent and positive controls.

Vehicle / solvent:

DMSO(dimethylsulfoxide)

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

other: Cyclophospharnide monohydrate

Details on test system and experimental conditions:

A preliminary test for the In Vitro Mammalian Chromosome Aberration Test of the test material was performed in this lab to evaluate the cytotoxicity and solubility in the culture medium of the test item. The CHL cells were used in the preliminary study, and DMSO was used as solvent. The cells were exposed for 3 hours and 24 hours without metabolic activation. The concurrent solvent control was included ateach treatment condition. The cells were exposed to a concentration band of 5000, 2000, 400, 80, and 16 µglml. The cultures were observed by naked eyes for test-item precipitation at the beginning and end of the treatment. The cell cultures were counted 24 hours after the beginning of cell exposure, and the cytotoxicity of the test item was evaluated. The results showed that there was no precipitation of test item in the cultures before and after incubation. The test item showed dose-related cytotoxicity.

Dose selection was determined based on the results of the preliminary test, and SEPA Guidelines for Testing of Chemicals. The test was conducted respectively in three treatment conditions of exposure for 3 hours with and without metabolic activation, and exposure for 24 hours without metabolic activation. Six doses of
5000, 1667, 555, 185, 61.7 and 20.6µglmlwere included in each treatment condition along with the concurrent solvent and positive controls.

1.00580 g test item was weighed and prepared as the 1000 mglml working solution. Under asepsis conditions, the working solutions of the other concentrations were prepared by dilution. The prepared working solutions were put in the asepsis tube labeled with study No. and concentration.

Approximately 2x 10^5 CHL cells were seeded in the cell culture plate and cultured overnight. Duplicate cultures were included at each dose level and control. Before being treated, the cells were washed with HBSS solution, and the mixtures used for each culture during cell treatment were prepared. Test solution and solvent were added to the corresponding mixtures. The cultures were observed for test item precipitation before and after the treatment. After the treatment, the cells were washed several times with HBSS solution and recultured in new 10% MEM.

24 hours after the beginning of cell treatment, all cells were treated with Colchicine for nearly 2hours at the final concentration of 1 µg/ml, and harvested.
Cells were harvested and washed with HBSS solution and treated with trypsin solution. Then the medium containing FBS were added to the cultures and mixed repeatedly. After all of these procedures, the cells of each dose and control were counted using a haemocytometer under inverted Microscope and the relative increase in cell count (RJCC) were calculated to evaluate the cytotoxicity.

According to the cytotoxicity result, the cells exposed at the doses of 5000, 1667and 555 µg/ml for 3h with metabolic activation and 24h without metabolic
activation and at the doses of 667, 555 and 185µg/ml for 3h without metabolic activation were chosen for chromosome preparation as the procedures below:Harvested cells were transferred into tubes to remove the media by centrifugation at 1000 rpm for 5 minutes. Remove the supemate, add 1ml of 75 mM KCL hypotonic solution preheated at 37°C and mix. Then incubate samples at 37°C for 40 minutes, and centrifuge at 1,000 rpm for 5 minutes. Remove the supemate, add 1.0 ml freshly prepared Carnoy's mixture slowly, mix gently with a pipette, and fix for 30 minutes. Remove the supemate, add 1 ml Carney's mixture, incubate at 2-8°C overnight(> 12h). Centrifuge the samples at 1,000 rpm for 5 minutes, remove the supemate, and add 0.2 ml Camey's mixture to get the cell suspension. Drop the cell suspension to clean slide, make at least 2 slides per group, dry them naturally at room temperature. Stain the samples with Giemsa solution for 30 minutes, wash them with water and dry them naturally.

Evaluation criteria:

CRITERIA OF POSITIVE RESULT:

Providing that all acceptability criteria below are fulfilled in any of the experimental conditions examined, the result is considered to be clearly positive:
1) At least one of the exposure dose exhibits a statistically significant increase in the percentage of cells with structural chromosomal aberration compared with
the concurrent solvent control (P<0.05);
2) The increase is dose-related

CRITERIA OF NEGATIVE RESULT:

Providing that all criteria below are fulfilled in all of the treatment conditions examined, the result is considered to be clearly negative:
1) None of the exposure doses exhibits a statistically significant increase compared with the concurrent solvent control (P > 0.05);
2) There is no dose-related increase

CRITERIA OF EQUIVOCAL RESULT:
In case the response is neither clearly negative nor clearly positive, additional cells should be scored and the biological relevance of the result should be
considered. If the result is not yet clear, a repeat experiment will be performed using modified experimental conditions. If the result in the repeat experiment is
still equivocal, the test item will be conclude to be equivocal.

Key result

Species / strain:

Chinese hamster lung (CHL/IU)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

True negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

No precipitation was observed in the cell cultures at all doses in three treatment condition at the beginning and end of the treatment.

The results for cytotoxicity showed that the RICC of the cells exposed for 3h in the absence of S9 mix at the doses of 5000, 1667, 555, 185, 61.7 and 20.6 µg/ml were 52%, 64%, 76%, 88%, 92% and 99%; the RICC of the cells exposed for 3h in the presence of S9 mix at the doses of 5000, 1667, 555, 185, 61.7 and 20.6 µg/ml were 54%, 64%, 80%, 87%, 93% and 91%; the RICC of the cells exposed for 24h in the absence of S9 mix at the doses of 5000, 1667, 555, 185, 61.7 and 20.6 µg/ml were 31%, 50%, 88%, 93%, 94% and 97%.

The results of the microscopic analysis showed that no statistically significant difference (P>0.05) in the percentage of cells with structural chromosomal
aberration was observed in all treated cells in each treatment condition as compared with the solvent control, at the same time, statistically significant
differences (P<0.01) were observed in the cells of all positive controls as compared with the solvent controls.

The results of the solvent control showed that the population doubling of cells in each treatment condition was more than 1.4 and statistically significant differences (P<0.01) were observed in the cells of all positive controls as compared with the

solvent controls. So the sensitivity of the assay and the efficacy of the S9 mix were validated, and the test system of this study was considered valid.

Conclusions:

The results of this test in all treatment conditions are negative, thus, it is considered that the test item, FMPBA did not cause structural chromosomal aberrations in cultured mammalian cells under the conditions of this study.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

Based on the results of the in vivo comet assay, there was no indication of genetic toxicity.

Link to relevant study records

Reference

Endpoint:

in vivo mammalian cell study: DNA damage and/or repair

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21/02/2019 to 16/05/2019

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 489 (In vivo Mammalian Alkaline Comet Assay)

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian comet assay

Specific details on test material used for the study:

Off white Powder
CAS No. 352303-67-4
Water Solubility: 3.62 g/L
Batch No. 18362500

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

Age at time of initial administration: 6-8 weeks old
Body Weight: Females 166.1-186.7g; Males 175.8-201.6

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal Quarantine and Acclimatization:
The animals introduced were quarantined and domesticated for 4 days. During quarantine, the animals were observed for water and food intake, healthy status, as well as for signs of illness and death. After the health status was confirmed by the Attending Veterinarian, animals were assigned to different experimental groups.

Housing Conditions:
Animals were housed in the polypropylene plastic boxes with the cage size of 423 mm x 269 mm. Two animals of the same gender were group-housed in one cage. Room temperature and relative humidity were maintained in the ranges of 20.04 - 23.75°C and 42.91-74.19 %RH, respectively. Lighting was controlled to provide 12 h of light and 12 h of darkness in a 24-hour period. Ventiliation controlled at a rate of at least 15 times of air exchanges per hour. Bedding and cages were replaced twice per week. Diets and drinking water were given to animals ad libitum, unless specified, throughout the course of study.

Route of administration:

oral: gavage

Vehicle:

Corn Oil

Details on exposure:

Five experimental groups were designed in the study with 40 animals (25 males and 15 females) in total, as illustrated in Table below. Group size was 10 animals/ group (5/group/sex) for 3 dosage groups and 5 males/group for 2 control groups. FMPBA was given to animals at three dose levels of 360 mg/kg (high dose), 180 mg/kg (medium dose) or 90 mg/kg (low dose). The positive control was EMS at the dose of 200 mg/kg. The negative control is the formulation vehicle of corn oil.

Duration of treatment / exposure:

Test substance or vehicle was given to animals at Oh, 24h, and 45h for 3 treatments

Frequency of treatment:

Test substance or vehicle was given to animals at Oh, 24h, and 45h for 3 treatments by gastric gavage using a round-tip gavage needle (size 12) and the sterile syringes. Positive control of EMS was given to animals for two treatments at 24h and 45h. The dosage volume was 10 mL/kg. Animals were deprived of food overnight (about 16 hours) before administration, and were restored 1-2 hours after administration. Animals had free access to drinking
water all through the study.

Post exposure period:

Cage-side observations: All animals before grouping and experimental animals after grouping were observed once daily for morbidity and mortality, appearance, fur, activity, reaction, breathing state, posture. Body weight: Animal body weight was weighed using the electronic balance. All animals were weighted upon arrival, group assignment, and before the initial dosing. Tissues were harvested 3 hours after the last dosing. all animals were anesthetized with 100% carbon dioxide (C02) via inhalation.

Dose / conc.:

90 mg/kg bw/day

Dose / conc.:

180 mg/kg bw/day

Dose / conc.:

360 mg/kg bw/day

No. of animals per sex per dose:

5 male/5 female per dose
5 males for negative and positive control groups

Control animals:

yes, concurrent vehicle

Positive control(s):

Ethyl Methanesulfonate (EMS)

Tissues and cell types examined:

Liver tissue collection: Tissues were removed, dissected and a portion about 5mm3 in the middle of left lobe was collected and weighed immediately for single cell suspension preparation.

Details of tissue and slide preparation:

Single cell suspension preparation: Tissues collected were minced immediately, rinsed with mincing buffer (20 mmol/L EDTA-Na2 in PBS), followed by gently grinded, and sieved through a 70 µm mesh screen. Tissues were maintained on ice during the procedure. Tissue homogenate were then centrifuged (4 'C, 1500 rpm, 10 min) and re-suspended with mincing buffer to make single cell suspensions. Slides precreation: Low melting point agarose (LM) was preheated before use according to the kit manual. Taken 50 µL single cell suspension solutions and added into 500 µL melted agarose, followed by gently mixed with a pipette. Taken 50 µL/well mixture and placed onto slides provide by the kit. One slide labeled individually was prepared for each animal.
Cell lysis: Once prepared, slides were placed into the refrigerator (2-8'C) for 30 minutes under subdued lighting conditions, and immersed in chilled lysing solutions (lysis buffer: DMSO=lO:l) overnight in the refrigerator.
Unwinding and electrophoresis: After incubation, slides were rinsed by purified water and placed into chilled alkaline lysis buffer (pH> 13) for unwinding at room temperature for 20 minutes. Slides were then subjected to electrophoresis under the conditions of 0.7V/cm for 20 minutes in the dark with the pre-cooled electrophoresis buffer (300 mM NaOH, lmM EDTA). After electrophoresis, slides were rinsed by purified water for twice, and dried with absolute ethanol at 37'C for I 5 minutes.
Slides were stained with 100 µL diluted Gene Red staining solutions for staining 30 minutes in the dark. After being dried at 37'C for 15 minutes, slides were examined with fluoresce microscope (200x) and captured with the camera.

Statistics:

The mean and standard deviation of % Tail DNA and hedgehog cells in each group were calculated and plotted using Microsoft Office. The data were expressed as mean ± standard deviation (X ± SD).
Due to uneven variance, the Welch's t-test were used to analyze inter-group difference between negative control (vehicle) group and each dose group or positive control group by SPSS software (IBM, version 19.0). When the p value is less than 0.05 (p<0.05), the inter-group difference is considered statistically significant, and p<0.01 as highly statistically significant.

Sex:

male/female

Genotoxicity:

negative

Remarks:

In animals given with FMPBA at dose levels of 90 mg/kg, 180 mg/kg, and 360 mg/kg, the% tail DNA was 1.28±0.56, 1.17±0.21, and 1.77±0.49

Toxicity:

no effects

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

One female animal (#39) in the medium dose group was found dead after the 2nd administration of test substance. Necropsy was performed and the causes of death was found to be due to gavage dosing procedures and thus determined not related to the treatment. No other animals were found morbid or moribund during the study.

Throughout the course of the study, no clinical signs were observed to be related with test substance administration. Individual cage-side observations results were presented

Conclusions:

Under the testing conditions of this study, the test substance FMPBA within the dose range of 90-360 mg/kg b.w. did not induce DNA strand breakage in the liver of rats.

Executive summary:

This study was designed according to theTesting Guidance of 489"Invivo Mammalian Comet Assay, OECD Guideline for the Testing of Chemicals, 2014".The objective  of the study  was to measure DNA strand breaks  in  rats orally administrated with test substance of FMPBA and evaluate its potential genotoxic risks.

Sprague Dawley (SD) rats were used in the study and randomized into five treatment groups:three dosage groups with 10 animals/group (5/group/sex) and two control groups, i.e. negative control and positive control groups, with 5  male animals/group. The test substance FMPBA was given to animals at the dose of 360mg/kgb.w., 180 mg/kgb.w.or 90mg/kgb.w. by gastric gavage at Oh, 24h and 45h for 3 times.Animals in negative control group were given with vehicle of corn oil in the same manner as test substance.  Animals positive control group were given twice with 200mg/kg ethyl methanesulfonate (EMS) at 24h and 45h. Liver tissues were collected from all animals within 3 hours after the last administration. Single cell suspension was prepared on slides for staining and microscopic examination. For each sample, 150 cells excluding hedgehogs were analyzed on the % tail DNA ,tail length and tail moment. The % tail DNA was used as indicator to evaluate DNA strand breaks caused by the test substance.

Results showed tha tthe % tail DNA in positive group was 17.55±4.04, which was significantly  higher than that of negative control group of corn oil 0.67 +/- 0.13 (p<0.01), indicating that the test system was reliable in this study. In animals given the given with FMPBA,  the % tail DNA was 1.28±0.56,  1.17±0.21,  and 1.77±0.49 for the dose levels of 90mg/kg, 180 mg/kg, and 360 mg/kg, respectively, all of which were not significant different from that of negative control group (p>0.05) and there was no dose-related relevance.The test chemical is thus considered negative

in this comet assay.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)