cis-N-methyl-N-(1H-pyrrolo[2,3-d]pyrimidin4-yl)cyclobutane-1,3-diamine phosphate (1:1)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

The experimental start date was 03 Dec 2018, and the experimental completion date was 11 Dec 2018.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 442C (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA))

GLP compliance:

yes

Type of study:

direct peptide reactivity assay (DPRA)

Test material

Test material information

1

Reference substance name:

(1s,3s)-N1-methyl-N1-{7H-pyrrolo[2,3-d]pyrimidin-4-yl}cyclobutane-1,3-diamine; phosphoric acid

EC Number:

951-920-2

Molecular formula:

C11H15N5* H3PO4

IUPAC Name:

(1s,3s)-N1-methyl-N1-{7H-pyrrolo[2,3-d]pyrimidin-4-yl}cyclobutane-1,3-diamine; phosphoric acid

Results and discussion

In vitro / in chemico

Results

Results 1

Run / experiment:

other: SPCC depletion

Parameter:

other: Cysteine 1:10 / Lysine 1:50

Value:

1.7

Positive controls validity:

valid

Remarks on result:

not determinable

Remarks:

Negative: No or minimal reactivity

Results 2

Run / experiment:

other: SPCL depletion

Parameter:

other: Cysteine 1:10 / Lysine 1:50

Value:

0.6

Positive controls validity:

valid

Remarks on result:

not determinable

Remarks:

Negative: No or minimal reactivity

Applicant's summary and conclusion

Interpretation of results:

study cannot be used for classification

Conclusions:

In conclusion, since all acceptability criteria were met this DPRA is considered to be valid.
PF-03817968-09 was negative in the DPRA and was classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model. However, since the DPRA study was performed using a test item stock solution with a concentration of 25 mM instead of the required 100 mM, no firm conclusion on the lack of reactivity can be drawn from this negative result.

Executive summary:

The objective of this study was to determine the reactivity ofPF-03817968-09 towards model synthetic peptides containing either cysteine (SPCC) or lysine (SPCL). After incubation of the test item with either SPCC or SPCL, the relative peptide concentration was determined by High-Performance Liquid Chromatography (HPLC) with gradient elution and spectrophotometric detection at 220nmand 258nm.SPCC and SPCL Percent Depletion Values were calculated and used in a prediction model which allows assigning the test item to one of four reactivity classes used to support the discrimination between sensitizers and nonsensitizers. The study procedures described in this report were based on the most recent OECD guideline. No appropriate solvent was found to dissolve the test item at a concentration of 100 mM. Milli-Q water(MQ)was found to be an appropriate solvent to dissolve the test item at a concentration of 25 mM and was, after consultation with the Sponsor, used in this Direct Peptide Reactivity Assay (DPRA) study.

The validation parameters, i.e. calibration curve, mean concentration of Reference Control (RC) samples A, C and CMQ, the CV for RC samples B and C, the mean percent peptide depletion values for the positive control with its standard deviation value and the standard deviation value of the peptide depletion for the test item, were all within the acceptability criteria for the DPRA. Upon preparation as well as after incubation of the SPCC and SPCL test item samples, no precipitate or phase separation was observed in any of the samples. An overview of the individual results of the cysteine and lysine reactivity assays as well as the mean of the SPCC and SPCL depletion are presented in the table below. In the cysteine reactivity assay the test item showed 1.7% SPCC depletion while in the lysine reactivity assay the test item showed 0.6% SPCL depletion. The mean of the SPCC and SPCL depletion was 1.1% and as a result the test item was considered to be negative in the DPRA and classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model.

In conclusion, since all acceptability criteria were met this DPRA is considered to be valid. PF-03817968-09 was negative in the DPRA and was classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model. However, since the DPRA study was performed using a test item stock solution with a concentration of 25 mM instead of the required 100 mM, no firm conclusion on the lack of reactivity can be drawn from this negative result.