Clinical investigation of the novel iron-chelating agent, CP94, to enhance topical photodynamic therapy of nodular basal cell carcinoma.
BACKGROUND
Photodynamic therapy (PDT) involves the activation of a photosensitizer by visible light to produce activated oxygen species within target cells, resulting in their destruction. Evidence-based guidelines support the efficacy of PDT using topical 5-aminolaevulinic acid (ALA-PDT) in actinic keratoses, Bowen disease and basal cell carcinoma (BCC). Efficacy for nodular BCC appears inferior to that for superficial BCC unless prior debulking or repeat treatments are performed. Objectives The aim of this study was to assess the safety and efficacy of adding a novel iron-chelating agent, CP94 (1,2-diethyl-3-hydroxypyridin-4-one hydrochloride), to topical ALA, to temporarily increase the accumulation of the photosensitizer in the tumour.


METHODS
A mixed topical formulation of ALA + increasing concentrations of CP94 was used to carry out PDT on previously biopsied nodular BCC with no prior lesion preparation using standard light delivery. The area was assessed clinically and surgically excised 6 weeks later for histological examination.


RESULTS
Enhanced PDT using 40% CP94 resulted in significantly greater clearance rates in nodular BCC than with ALA-PDT alone, in our protocol of single-treatment PDT with no lesion preparation.


CONCLUSIONS
The results of this study demonstrate the safe and effective use of an enhanced ALA-PDT protocol for nodular BCC using CP94, with no adverse reactions to this modification. This is the first time this formulation has been used in patients. This formulation is now the focus of further study.
Cornwall Dermatology Research, Peninsula Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall TR1 3LJ, UK. sandra.campbell@rcht.cornwall.nhs.uk
S M
SM
Campbell
C A
CA
Morton
R
R
Alyahya
S
S
Horton
A
A
Pye
A
A
Curnow
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000622:Aminolevulinic Acid / Q000627:therapeutic use; D002280:Basal Cell Carcinoma / Q000188:drug therapy* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007502:Iron Chelating Agents / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology; D010778:Photochemotherapy / Q000009:adverse effects / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D010865:Pilot Projects; D011728:Pyridones / Q000009:adverse effects / Q000627:therapeutic use*; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000473:pathology; D016896:Treatment Outcome
D007502:Iron Chelating Agents; D017319:Photosensitizing Agents; D011728:Pyridones; C068543:1,2-diethyl-3-hydroxypyridin-4-one; D000622:Aminolevulinic Acid