Soligenix, Inc. announced that post-treatment data from the open-label study (HPN-CTCL-04) comparing HyBryte (synthetic hypericin) to Valchlor (mechlorethamine) in patients with cutaneous T-cell lymphoma (CTCL) demonstrated continued improvement in HyBryte-treated patients and their individual lesions even after stopping treatment. The study, involving 10 patients randomized 1:1, showed that HyBryte maintained efficacy 4 weeks post-treatment.
The HPN-CTCL-04 study involved 12 weeks of treatment followed by a 4-week follow-up. Initial results showed a 60% treatment response rate in the HyBryte group versus 20% in the Valchlor group. By week 16, a majority (3 of 5) of HyBryte patients showed at least a 10% further improvement relative to week 12, including one achieving a complete response. In contrast, none of the four Valchlor patients achieved this level of improvement.
Efficacy Against Plaque Lesions
Notably, HyBryte demonstrated significant efficacy against plaque lesions, which are increasingly associated with disease progression and mortality. At week 12, 63% of HyBryte-treated plaque lesions showed treatment success versus 17% with Valchlor (p=0.02). By week 16, HyBryte's response rates were statistically significant for all lesions (72% vs 28%, p=0.02) and specifically for plaque lesions (75% vs 17%, p=0.006).
Safety Profile
HyBryte was well-tolerated, with no related adverse events reported during the follow-up. In contrast, 60% of Valchlor-treated patients experienced related adverse events, including rashes, application site sensitivity, and allergic contact dermatitis, leading to steroid treatment, treatment interruption, or discontinuation in some cases.
Expert Commentary
Dr. Brian Poligone, Director of the Rochester Skin Lymphoma Medical Group, stated, "Despite the small study sample size and a randomization that resulted in the HyBryte group having patients with more extensive disease, HyBryte continues to demonstrate its rapid onset of action and benign safety profile, compared to one of the most widely prescribed approved drugs for early-stage CTCL."
Ongoing Development
Soligenix plans to initiate the 80-patient confirmatory Phase 3 replication study (FLASH2) next month. This study replicates the design of the first Phase 3 FLASH study, with an extended 18-week treatment cycle. Christopher J. Schaber, PhD, President and CEO of Soligenix, noted, "These results support the positive HyBryte data from the previously completed Phase 3 FLASH study and demonstrates that a relatively short treatment period with the drug can result in clinically meaningful outcomes."
About HyBryte
HyBryte (SGX301) is a photodynamic therapy using visible light for activation. The active ingredient, synthetic hypericin, is applied topically and activated by visible light, avoiding the risks of DNA-damaging drugs and ultraviolet exposure. It has shown anti-proliferative effects on malignant T-cells and has received orphan drug and fast track designations from the FDA and EMA.
Cutaneous T-Cell Lymphoma (CTCL)
CTCL is a rare form of non-Hodgkin's lymphoma affecting T-cell lymphocytes in the skin. It affects approximately 31,000 individuals in the U.S. and 38,000 in Europe. While treatments can regress lesions, they often recur. There is currently no cure for CTCL.
