# Presentation: 529371

## FDA/NIEHS Phototoxicology Research and Testing Laboratory&NTP Center for Phototoxicology

**Notes:**
As part of the IAG between the FDA and NIEHS, a laboratory facility was constructed to allow us to address the safety of drugs, cosmetics and cosmeticeuticals in the presence of various forms of light.  This facility, the FDA/NIEHS Phototoxicolgoy Research and Testing Laboratory has also been designated at one of the National Toxicology Program Centers of Research Excellence, and is referred to at the NTP Center for Phototoxicology

## NTP Research Centers

- • NTP Center for the Evaluation of Risks to Human Reproduction (CERHR)
- • Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM)
- • National Center for Toxicogenomics (NCT)
- • NTP Center for Phototoxicology

**Notes:**
As part of the IAG between the FDA and NIEHS, a laboratory facility was constructed to allow us to address the safety of drugs, cosmetics and cosmeticeuticals in the presence of various forms of light.  This facility, the FDA/NIEHS Phototoxicolgoy Research and Testing Laboratory has also been designated at one of the National Toxicology Program Centers of Research Excellence, and is referred to at the NTP Center for Phototoxicology

## NTP  Center for Phototoxicology

- Purpose is to provide the expertise and facility that will allow the conduct of toxicological studies which require exposure of animals to light-emitting sources.

**Notes:**
As part of the IAG between the FDA and NIEHS, a laboratory facility was constructed to allow us to address the safety of drugs, cosmetics and cosmeticeuticals in the presence of various forms of light.  This facility, the FDA/NIEHS Phototoxicolgoy Research and Testing Laboratory has also been designated at one of the National Toxicology Program Centers of Research Excellence, and is referred to at the NTP Center for Phototoxicology

## AHA/BHA Products

**Notes:**
The nomination of the alpha- and beta-hydroxy acids to the IAG by the Office of Cosmetics and Colors at CFSAN was the catalyst for construction of the Center for Phototoxicology.  The alpha- and beta-hydroxy acids are included in a large percentage of cosmetics.  The inclusion of these compounds and the very acidic pH (3-5) of the creams results in discohesion and removal of the strateum corneum and upper cells of the epidermis.  The regeneration and restructuring of the skin results in a more “youthful looking” skin.  

However, these products are used primarily by women who have photoaged skin.  Therefore, the combination of increased epidermal basal cell proliferation when using the cosmetics and excessive exposure to sunlight suggested a possible increase in skin cancer.

The challenge was to develop or adapt a rodent model for sunlight induced skin cancer in humans.

## What light source should we use?

## What light source should we use?

## What light source should we use?

## What light source should we use?

## What light source should we use?

## Spectral 

- <date/time>

**Spectral **
**Comparison of **
**Sunlight, and**
**Simulated Solar**
**Light**

## 6.5 kWatt xenon-arc lamp with 6x6 inch quartz glass filters (8 positions)

**Notes:**
Sunlight is simulated in the animal exposure room using a xenon-arc light operating at 6,500 Watts.  At present the we are generating light with a UV component fairly equivalent to the Carribean; however, by changing the quartz filters, we can generate light eauivalent to anywhere on the planet, including areas under an ozone hole. 

Each animal rack (shown in background) receives light from one of the eight quartz filters.  Although all the quartz filters are a matched set for the current animal studies, the filters can readily be changed to allow simultaneous exposure of mice in adjacent racks to different spectra of light.

- SKH-1 hairless mouse
- albino; juvenile but not adult hair
- immunocompetent
- primary animal for photocarcinogenicity studies

**Notes:**
Fortunately for us, scientists formerly at Temple University at now at Argus Research Laboratories, developed a mouse model for sunlight induced skin cancer.  

Shown in this picture is the SKH-1 hairless mouse.  It is an immunocompetent inbred mouse that fails to develop adult hair.  This mouse has been used since the late 1970’s as the principal mouse for photocarcinogenesis studies.

## Slide 13

**Notes:**
The mice are housed and exposed in specially designed racks from Lenderking Caging Corp.

## AHA/BHA Photococarcinogenesis Study (started 17 July 2000)

**Amount of             Simulated Solar Light**

**Number of mice/sex presented in boxes**

**Notes:**
This figure shows a typical experimental design for one of the photococarcinogenicity studies. The mice are treated 5 days/week for 40 weeks, then held without treatment for 12 weeks prior to sacrifice and necropsy. Our positive control is the induction of skin cancer with the medium and high doses of simulated sunlight.  The medium dose will induce skin cancer in 100% of the mice in that group in about 40 weeks.  This level of light is a suberythemal dose of light, approximately 15-20% of the light required for a sunburn.  
A positive cocarcinogen might cause a shift in the median time to first tumor, may increase the total number of tumors, or may alter the distribution of tumor types.

All of the creams used in this study are reflective of creams used in over-the-counter cosmetics.

## NTP Center for Phototoxicology

- Really depends on the types of studies (# dose groups? female and male? vehicle?)
- Housing for ~6000 mice
- Depending on study design can expose up to ~4000 mice per afternoon with current 2 simulated solar lights

***Facility Capacity***

**Notes:**
Depending on the type of study in the facility, we can accommodate anywhere from 3-5 simultaneous studies.

We have 6 animal housing rooms, each capable of holding 14 of the special racks, giving each room a capacity of 1000 mice.

With 2 simulated solar light units, we can process approximately 4000 mice through the facility in an afternoon.

## NTP Center for Phototoxicology

- Alpha- & Beta- hydroxy acids (IAG/CFSAN; P. Howard; FY99-02)
- Skin care creams containing alpha- (glycolic acid) or beta-hydroxy acids (salicylic acid) are used in over-the-counter cosmetics to facilitate corneocyte discohesion and epidermal regeneration.  This results in a “smoother” looking skin.

***CURRENT STUDIES***

**Notes:**
This figure shows the studies currently underway.

AHA/BHA animal work will be completed this fall, and we expect a completion of the final report in late 2002.

The studies on the effects of topical application of aloe vera and retinyl palmitate are just beginning and be completed sometime in 2004 or 2005.

The FDA and many other agencies have noted a deficiency in animal models for human cutaneous melanoma development.  We are collaborating with Lynda Chen at Harvard and are testing a p16/INK4a heterozygotic mouse  as a murine melanoma model.  These studies are being funded with FDA resources, but will impact the IAG if successful.

## NTP Center for Phototoxicology

- Alpha- & Beta- hydroxy acids (IAG/CFSAN; P. Howard; FY99-02)
- - mechanistic studies to understand the effect of the creams on epidermal cell proliferation and epidermal differentiation
- -1-year photococarcinogenesis study

***CURRENT STUDIES***

**Notes:**
This figure shows the studies currently underway.

AHA/BHA animal work will be completed this fall, and we expect a completion of the final report in late 2002.

The studies on the effects of topical application of aloe vera and retinyl palmitate are just beginning and be completed sometime in 2004 or 2005.

The FDA and many other agencies have noted a deficiency in animal models for human cutaneous melanoma development.  We are collaborating with Lynda Chen at Harvard and are testing a p16/INK4a heterozygotic mouse  as a murine melanoma model.  These studies are being funded with FDA resources, but will impact the IAG if successful.

## NTP Center for Phototoxicology

- Aloe vera (IAG/NCI; M. Boudreau; FY01-FY04)
- Contained in many over-the-counter cosmetics, lotions, shampoos, etc. Is also used as dietary supplement.
- -in vivo phototoxicity of topical aloe and sunlight
- -mechanistic studies on epidermal cell proliferation
- - 1-year photococarcinogenesis study

***CURRENT STUDIES***

**Notes:**
This figure shows the studies currently underway.

AHA/BHA animal work will be completed this fall, and we expect a completion of the final report in late 2002.

The studies on the effects of topical application of aloe vera and retinyl palmitate are just beginning and be completed sometime in 2004 or 2005.

The FDA and many other agencies have noted a deficiency in animal models for human cutaneous melanoma development.  We are collaborating with Lynda Chen at Harvard and are testing a p16/INK4a heterozygotic mouse  as a murine melanoma model.  These studies are being funded with FDA resources, but will impact the IAG if successful.

## NTP Center for Phototoxicology

- Retinyl palmitate (IAG/CFSAN; S. Culp; FY01-04)
- RP is added to man over-the-counter cosmetics and the role of RP or metabolites (retinol) in photocarcinogenesis is not known
- - mechanistic studies
- - photococarcinogenesis study

***CURRENT STUDIES***

**Notes:**
This figure shows the studies currently underway.

AHA/BHA animal work will be completed this fall, and we expect a completion of the final report in late 2002.

The studies on the effects of topical application of aloe vera and retinyl palmitate are just beginning and be completed sometime in 2004 or 2005.

The FDA and many other agencies have noted a deficiency in animal models for human cutaneous melanoma development.  We are collaborating with Lynda Chen at Harvard and are testing a p16/INK4a heterozygotic mouse  as a murine melanoma model.  These studies are being funded with FDA resources, but will impact the IAG if successful.

## NTP Center for Phototoxicology

- TP-*ras*(+/+),*p16*/INK4a(+/-) Mouse melanoma model (NCTR; W. Tolleson; FY01-04)
- There is currently no acceptable animal model to study the role of sunlight in melanoma development.  This is one of two promising mouse models.

***CURRENT STUDIES***

**Notes:**
This figure shows the studies currently underway.

AHA/BHA animal work will be completed this fall, and we expect a completion of the final report in late 2002.

The studies on the effects of topical application of aloe vera and retinyl palmitate are just beginning and be completed sometime in 2004 or 2005.

The FDA and many other agencies have noted a deficiency in animal models for human cutaneous melanoma development.  We are collaborating with Lynda Chen at Harvard and are testing a p16/INK4a heterozygotic mouse  as a murine melanoma model.  These studies are being funded with FDA resources, but will impact the IAG if successful.

## NTP Center for Phototoxicology

- CRADA on historical database with SKH-1 (NCTR; P. Howard; FY01-02)
- PUVA exposure and application of gene chip technology for biomarkers (IAG/NIEHS; P. Howard; FY01)

***CURRENT STUDIES***

**Notes:**
In collaboration with Argus Research Laboratories, we are creating a database of 12 of their previous photocarcinogenesis studies with SKH-1 mice.  This will give us the ability to (1) examine statistical methods for data analysis, and (2) compare our results with historical controls at Argus.

The NIEHS approached us concerning the application of gene chip array technology in examining gene expression changes in mice treated with psoralen plus UVA.  PUVA treatment is still used in psorasis therapy and treating other skin diseases.  The validation of a biomarker of PUVA-induced skin cancer would be clinically helpful .

## NTP Center for Phototoxicology

- Padimate O (sunscreen) (IAG/NTP; P. Howard; FY02-06)
- Oxypeucedanin and furocoumarins in lemon and lime oil (IAG/CFSAN; FY03-07)
- Dyes D&C 27 and 28 (IAG/CFSAN; FY04-08)
- PUVA2, kinetics of biomarker changes (IAG/NCTR, NIEHS; P. Howard; FY02-04)
-  Environmental stress effects and circadian rythyms in SKH-1 (NCTR; P. Howard; FY02-03)

*FUTURE PLANS*

**Notes:**
Future studies in the NTP Center for Phototoxicology have been outlined in this slide.

Padimate O is a sunscreen agent still used in cosmetics. It was nominated to the NTP program by a private citizen, and will be studied in the Phototox Center.

These other studies will meet the needs of the IAG, testing the safety of compounds relevant to the regulatory mission of the FDA and scientific mission of the NIEHS and NTP.

## NTP Center for  Phototoxicology

-   *Meeting the basic science research and testing needs NTP, NIEHS, and FDA*

## NTP Center for Phototoxicology

**Notes:**
The studies conducted under the IAG not only involve 2-year tumor studies or 1-year photocarcinogenicity studies, but alos include mechanistic studies to determine the mechanism of action of the study compound. 

In the alpha- and beta- hydroxy acid studies, short-term in vivo studies have been used to investigate many aspects of the effects of these acids on murine skin.

Although there is insufficient time to begin to go over these studies, one example is work bringing out.

In these photomicrographs are shown the skin from control mice (upper left), mice treated with cream containing 4% salicylic acid (upper right), or 10% glycolic acid (bottom).  Proliferating cells are shown as darkly stained cells with this immunohistochemical slide (anti-BrdU).

## NTP Center for Phototoxicology

**Notes:**
One critical question in the design of the 1-year photococarcinogenesis study was when do we apply the creams and when do we expose to light?

The result sof one of the mechanistic studies is shown in this figure.  The data shows that 12-16 hours after application of cream containing glycolic acid there is a “wave” of cell proliferation in the epidermis. creamsThis is followed by an increase in epidermal cell mass (skin thickness). 

We were able to use this data to support a study design of cream in the morning and light in the afternoon.