Standardized protocols for photocarcinogenesis safety testing

Area of Science:

• Photobiology
• Dermatology
• Toxicology

Background:

• Solar ultraviolet radiation (UVR) is a known carcinogen, particularly for non-melanoma skin cancer.
• Exposure to photosensitizing agents and certain other drugs, like immunosuppressants, increases skin cancer risk.
• Regulatory agencies worldwide are evaluating methods to assess photocarcinogenesis risk for drugs and chemicals.

Purpose of the Study:

• To review the current understanding of UVR-induced skin cancer and factors that enhance it.
• To highlight the need for validated methods to assess photocarcinogenesis risk.
• To introduce published protocols for evaluating agents that may enhance UVR-induced skin tumors.

Main Methods:

• Review of existing literature on UVR carcinogenesis and photosensitization.
• Discussion of regulatory requirements for photocarcinogenesis assessment by agencies like the U.S. FDA and Health Canada.
• Description of newly published study designs for evaluating photocarcinogenic potential.

Main Results:

• Skin cancer incidence correlates with UVR exposure and is increased by photosensitizers and immunosuppressants.
• Current short-term tests lack validation as predictors of photocarcinogenic enhancement.
• New protocols offer a means to determine if agents enhance UVR-induced skin tumor development.

Conclusions:

• Validated methods are crucial for assessing the photocarcinogenic risk of drugs and chemicals.
• Published study designs provide a pathway for evaluating agents that may enhance UVR-induced skin cancer.
• Regulatory bodies are increasingly focused on the photocarcinogenesis potential of pharmaceutical products.