# Presentation: 687077

## Nonclinical Pharmacology/ Toxicology Data for PROTOPIC (Tacrolimus ointment for Atopic Dermatitis) 

- Barbara Hill, Ph.D.
- Division of Dermatologic and Dental Drug Products

## Outline

- Genotoxicity Studies
- Photocarcinogenicity Study
- Dermal Carcinogenicity Study
- Overall Summary

## Genotoxicity Studies

- Ames mutagenicity test (*Salmonella and E. coli*)
- Mammalian *in vitro* mutagenesis assay (Chinese hamster lung-derived cells)
*In vitro* CHO/HGPRT assay of mutagenicity
*In vivo* clastogenicity assays performed in mice
**Findings:**
- No genotoxicity signal noted in any of the assay systems

## Photocarcinogenicity Study

**Objective:**
- To determine in a hairless mouse model if dermal test article application combined with simulated sunlight exposure can reduce the time to formation of skin papillomas compared to simulated sunlight exposure alone

## Photocarcinogenicity Study

**Findings:**
- Topical administration of the vehicle ointment enhanced photo co-carcinogenesis (shorten time to skin tumor formation; greater for male mice)
- Topical administration of tacrolimus ointment had an additional small influence on skin tumor development beyond the vehicle effect (more prevalent in male mice)

## Photocarcinogenicity Study

**Conclusion:**
- Based on the results of the nonclinical photocarcinogenicity assay, the sponsor proposed that a precaution be included in the label for patients to minimize or avoid exposure to natural or artificial sunlight during the use of 0.03% and 0.1% tacrolimus ointment

## Dermal Carcinogenicity Study

**Objective:**
- To determine in a mouse model if daily dermal test article application can cause the formation of tumors at any organ site after two years of application

## Dermal Carcinogenicity Study

**Findings:**
- High levels of mortality were exhibited in the 0.3%, 1% and 3% tacrolimus ointment dose groups
- Statistically significant elevation in the incidence of pleomorphic lymphoma was noted in 0.1% tacrolimus ointment treated male (25/50) and female animals (27/50) compared to vehicle control male (2/50) and female animals (6/50)

## Dermal Carcinogenicity Study

**Findings:**
- Statistically significant elevation in the incidence of undifferentiated lymphoma was noted in 0.1% tacrolimus ointment treated female animals (13/50) compared to vehicle control female animals (1/50)

## Dermal Carcinogenicity Study

_**Neoplastic Findings in Tacrolimus Ointment Treated Mice (n = 50)**_

- Note: Relatively high mortality was noted in the 0.1% dose group

## Dermal Carcinogenicity Study

- The multiples of human systemic exposure levels ranged from 9 - 26 fold if the highest mean adult human AUC0-24 hr value (0.1% tacrolimus ointment) is used for the calculation
- Highest mean adult human AUC0-24 hr value (0.1% tacrolimus ointment) = 20.4 ng·ml/hr
- NOAEL mouse AUC0-24 hr value = 189 ng·ml/hr
- Lymphoma mouse AUC0-24 hr value =  534 ng·ml/hr
- NOAEL mouse/human exposure level = 189/20.4 = 9
- Lymphoma mouse/human exposure level = 534/20.4 = 26

## Dermal Carcinogenicity Study

- However, the multiples of human systemic exposure levels are much less (3 - 9 fold) if the highest obtained adult human AUC0-24 hr value (0.1% tacrolimus ointment) is used for the calculation
- Highest adult human AUC0-24 hr value (0.1% tacrolimus ointment) = 61.9 ng·ml/hr
- NOAEL mouse AUC0-24 hr value = 189 ng·ml/hr
- Lymphoma mouse AUC0-24 hr value =  534 ng·ml/hr
- NOAEL mouse/human exposure level = 189/61.9 = 3
- Lymphoma mouse/human exposure level = 534/61.9 = 9

## Dermal Carcinogenicity Study

**Conclusions:**
- The estimates of human systemic exposure data are highly variable and are dependent on the maximum body surface area that is treated in the atopic dermatitis patient
- It is unclear what the ratio of mouse to human systemic exposure levels would be for pediatric patients since adequate AUC data are not available at this time

## Dermal Carcinogenicity Study

**Conclusions:**
- Biologic plausibility of lymphoma formation in local lymph nodes can not be ruled out at this time
- It is acknowledged that demonstrating this effect could be technically challenging

## Summary

- The results of the photocarcinogenicity study suggest that tacrolimus ointment combined with simulated sunlight exposure shortens the time to skin tumor formation compared to simulated sunlight exposure alone

## Summary

- Lymphomas were noted at the 0.1% tacrolimus ointment dose in the dermal mouse carcinogenicity study
- The multiples of human systemic exposure  ranged from 3 - 26 fold
- The multiple of human systemic exposure calculation is highly variable and is dependent on the systemic exposure level noted in humans
- The best estimate would be obtained from maximum exposure conditions in pediatric patients