A new topical gel containing bexarotene, a form of vitamin A, is undergoing clinical trials at the Fox Chase Cancer Center in Philadelphia, to test its effect on parapsoriasis, a red, scaly rash which can often be a precursor to skin cancer.
Stuart Lessin, MD, director of the Dermatology Oncology Programme at Fox Chase Cancer Center, said that this was one of the few trials focusing on a precursor to cancer.
Parapsoriasis is a skin condition considered a precursor to cutaneous T-cell lymphoma (CTCL), a potentially deadly form of cancer that manifests in the skin and targets the body's white blood cells (lymphocytes), impairing the patient's immune system.
Parapsoriasis is different from psoriasis in both its appearance and location on the body. The skin condition starts as red, scaly rash that appears on the trunk of the body, instead of on the extremities.
"Parapsoriasis has the potential to progress to CTCL and differentiation between parapsoriasis and early stage CTCL can be difficult and often requires evaluation by an experienced specialist," said Lessin.
Patients can live with the complications of CTCL long after the initial diagnosis, and research suggests that as many as 16,000 people in the US are affected by the disease each year.
CTCL slowly progresses from scaling skin patches to larger areas of thickened plaques and then to tumour nodules, while in the late stages, the cancer grows to involve lymph nodes, blood and internal organs. Most patients die from infections due to breakdown of the skin and a crippled immune system.
The FDA has already approved Targretin, the bexarotene made by Ligand Pharmaceuticals which is being used in the trial, for the treatment of CTCL, but Lessin and his colleagues are using the gel as a prevention tool. "If we can treat patients who are diagnosed with parapsoriasis, we can potentially stop the cancer before it has a chance to start or progress," Lessin said.
Bexarotene (Targretin) is a type of retinoid, a synthetic form of vitamin A that binds to specific retinoid receptors and regulates cell function. The drug inhibits cancer growth and induces apoptosis, or programmed cell death.
In the trial, the topical gel is initially applied to the skin lesions everyday for two weeks, than twice a day for up to 16 weeks. Tissue from the skin lesions is taken or biopsied before and after treatment to determine response to the gel.
"We're hoping that patients suffering from parapsoriasis will respond to the Targretin therapy, thereby clearing up the uncomfortable condition and preventing further progression of the disease," Lessin said.