Topical protoporphyrin IX (PPIX) induced photodynamic therapy (PDT) of basal cell carcinoma (BCC) produces good
clinical outcomes with excellent cosmesis as long as the disease remains superficial. Efficacy for nodular BCC however
appears inferior to standard treatment unless repeat treatments are performed. Enhancement is therefore required and is
possible by employing iron chelating agents to temporarily increase PPIX accumulation above the levels normally
obtained using aminolevulinic acid (ALA) or the methyl ester of ALA (MAL) alone. In vitro studies investigated the
effect of the novel iron chelator, CP94 on necrotic or apoptotic cell death in cultured human skin fibroblasts and
epidermal carcinoma cells incubated with MAL. Furthermore, following a dose escalating safety study conducted with
ALA in patients, an additional twelve nodular BCCs were recruited for topical treatment with standard MAL-PDT +/-
increasing doses of CP94. Six weeks later following clinical assessment, the whole treatment site was excised for
histological analysis. CP94 produced greater cell death in vitro when administered in conjunction with MAL than this
porphyrin precursor could produce when administered alone. Clinically, PDT treatment using Metvix + CP94 was a
simple and safe modification associated with a trend of reduced tumor thickness with increasing CP94 dose.
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