A phase II placebo-controlled study of photodynamic therapy with topical hypericin and visible light irradiation in the treatment of cutaneous T-cell lymphoma and psoriasis

Background: Hypericin is a known photodynamic agent that has been demonstrated to induce apoptosis in normal and malignant B and T lymphocytes, and has potential to treat benign and malignant disorders of the skin, including psoriasis and cutaneous T-cell lymphoma. Objective: We wished to test whether topical hypericin was an effective, safe, and well-tolerated therapy for patch or plaque phase mycosis fungoides and for plaque psoriasis. Methods: We conducted a phase II placebo-controlled clinical study in patients who had either patch or plaque phase mycosis fungoides or plaque type psoriasis vulgaris. Representative lesions were treated twice weekly for 6 weeks with topically applied hypericin or placebo followed 24 hours later by exposure to visible light at 8 to 20 J/cm². Results: After 6 weeks of twice-weekly therapy, several concentrations of hypericin resulted in the significant improvement of treated skin lesions among the majority of patients with cutaneous T-cell lymphoma and psoriasis whereas the placebo vehicle was ineffective. Limitations: The clinical trial involved a small number of patients. Conclusions: Overall, the data from this study support the conclusion that topical hypericin/visible light photodynamic therapy is an effective and well-tolerated alternative to standard psoralen plus ultraviolet A treatment of these disorders.