Trial Information

Gene Expression in Renal Transplant Patients With Field Actinic Keratosis Undergoing Metvix® PDT

Transplant recipients have an increased propensity to develop multiple areas field of
cancerisation and subsequently to develop multiple actinic keratoses, which demonstrate an
increased transformation rate into invasive squamous cell carcinoma (SCC). The incidence of
cutaneous premalignant epithelial lesions such as actinic keratosis (AK) is increased
compared with the immunocompetent population with a mean occurrence of 38% after 5 years of
immunosuppression, compared with <5% in the immunocompetent patients. Since the development
of multiple AKs may portend further possibility extensive cutaneous carcinogenesis, early
and aggressive treatment is essential to prevent the progression to invasive SCC.

Although they may occur as single lesion, multiple actinic keratoses (AKs) are commonly
present in areas of chronic actinic damage (field of AKs or field of cancerisation). The
concept of "field cancerisation" suggests that the clinically normal appearing skin around
AKs provides the basis for clonal expansion of genetically altered neoplastic cells. This is
called sub-clinical AK lesions.

In this study, the whole target area defined by the investigator will be treated by Metvix
PDT: this means that both lesions and sub-clinical lesions will be exposed to Metvix PDT.
Biopsies will be performed in both regions: lesional and peri-lesional ones. This will allow
us to compare pre and post treatment molecular changes that occurred in these regions and so
to evaluate if Metvix PDT acts on the sub-clinical lesions.