Soligenix Submits NDA for Novel Therapy for Cutaneous T-cell Lymphoma

Soligenix has submitted a new drug application (NDA) to the FDA for HyBryte (synthetic hypericin) to treat patients with early stage cutaneous T-cell lymphoma (CTCL). Cutaneous T-cell lymphoma is a rare type of cancer that begins in T cells, which causes the immune system to attack the skin.

HyBryte is a novel photodynamic therapy. The active ingredient is synthetic hypericin, a potent photosensitizer that is topically applied to skin lesions that is taken up by the malignant T-cells, and then activated by visible light about 24 hours later.

Christopher J. Schaber, Ph.D.

“CTCL is an incredibly difficult to treat orphan disease and remains an area of unmet medical need with a very limited number of safe and effective treatment options,” Christopher J. Schaber, Ph.D., president and chief executive officer of Soligenix, said in a press release. “The clinical results we’ve generated throughout the development program support the potential for HyBryte to serve as an important front-line treatment in the management of this chronic cancer.”

In the phase 3 FLASH trial, which was published in July 2022 in JAMA Dermatology, 16% of the patients receiving HyBryte achieved at least a 50% reduction in their lesions compared with only 4% of patients in the placebo group at eight weeks during the first treatment cycle, which was the primary endpoint of the study. HyBryte treatment in the first cycle was safe and well tolerated.

The study enrolled a total of 169 patients (166 evaluable) with Stage IA, IB or IIA cutaneous T-cell lymphoma. The trial consisted of three treatment cycles. Treatments were administered twice weekly for the first six weeks and treatment response was determined at the end of the eighth week of each cycle.

For the second open-label treatment cycle, all patients received HyBryte treatment. This cycle evaluated 155 patients, including 110 who had previously received 12 weeks of HyBryte treatment and 45 who had received six weeks of placebo. The response rate among the patients who had previously received 12 weeks of treatment was 40%. Comparison of the 12-week and six-week treatment groups also revealed a statistically significant improvement between the two groups. Additional analyses also indicated that HyBryte is equally effective in treating both plaque and patch lesions of cutaneous T-cell lymphoma.

About 66% of patients in cycle two continued to cycle three, which was focused on safety. Of the subset of patients that received HyBryte throughout all three cycles of treatment, 49% of them demonstrated a positive treatment response. In the patients evaluated in this cycle, it was demonstrated that HyBryte is not systemically available, consistent with the general safety of this topical product observed to date. At the end of cycle thre, the therapy continued to be well tolerated.