Mycosis fungoides is the most common type of cutaneous T-cell lymphoma. This rare form of cancer occurs when the germ-fighting cells of the immune system (T-cells) begin to attack a person’s skin.
While the cause of mycosis fungoides remains unknown, it manifests as round, scaly patches of skin. The patches may be itchy, break open, and cause localized hair loss.
Treatment for mycosis fungoides is often dictated by the severity, or stage, of the disease. Treatments may range from medicated skin creams and ointments to radiation. The most common treatment is light therapy using a ultraviolet (UV) light. While effective, this type of treatment can lead to future cancers when used for a long time to treat a condition that persists.
A Phase 3 clinical trial evaluated the effectiveness and safety of a new treatment that uses an ointment activated by natural light. The results are available in the July issue of the journal JAMA Dermatology.
“This is a revolutionary, brand-new therapy which will expand how we care for our patients,” said Jennifer DeSimone, MD, Director of Cutaneous Lymphoma at the Inova Schar Cancer Institute and contributing author on the study.
The ointment contains hypericin, which is found naturally in plants like St. John’s Wort belonging to the genus Hypericum. Hypericin targets the diseased immune cells. When hypericin is exposed to light in the visible spectrum, it is activated, triggering a cascade of reactions that kills the cancerous cell. This discovery led to the creation of a synthetic hypericin ointment, called HyBryte. When paired with light in the yellow/red spectrum (500 to 650 nm wavelength), the ointment can penetrate up to 2 mm deep, about the thickness of two dimes, into skin tissue.
“This particular type of cancer is unique,” said DeSimone. “It is a cancer of the skin lymphocytes (immune cells) which are exquisitely sensitive to photosensitization and destruction by light.”
The FLASH Clinical Trial
DeSimone joined colleagues from 35 cancer centers across the country in the Phase 3 clinical trial, called FLASH (Fluorescent Light Activated Synthetic Hypericin). The study recruited 166 participants with early stage mycosis fungoides-cutaneous T-cell lymphoma. The participants were randomly assigned to one of two groups. One group received the treatment twice a week for six weeks. The second group received a placebo ointment twice a week for six weeks. After the initial phase of the study, each group stopped treatment for two weeks.
For the second and third phase of the study, the placebo group crossed over and received two six-week courses of the hypericin treatment. The hypericin group received a second and third six-week course of treatment.
During the first phase of the study, the hypericin group showed a reduction in the lesion by 16% using the index lesion response rate (ILRR). This value exceeded the placebo group that only showed 4% reduction in the lesion size. Participants who received the hypericin treatment for two consecutive phases showed a reduction in lesion size by 40% and 49% for three consecutive treatments.
The treatment was effective on both mycosis fungoides patches and plaques, suggesting penetration to various depths in the skin.
“I was excited to see that even in patients with thicker, deeper lesions, the lesions were cleared, which was unexpected and positive,” said DeSimone.
The results were limited by an abbreviated approach to treatment, which consisted of only three six-week periods. It did not differentiate the effect of skin pigmentation, lesion subtypes, or the presence or absence of large-cell transformation on the results. Despite these limitations, the study found the treatment was safe with only minor side effects, including skin reactions, itchy skin, and application site pain and/or irritation.
“We are hoping that this drug/device treatment will be commercially available soon,” said DeSimone. “We need more real-world use of this therapy to identify long-term trends and see define the role for this treatment in chronic disease.”