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Soligenix Inc. (NASDAQ: SNGX) Reaches Key Enrollment Milestone in Phase 3 Trial with Encouraging Blinded Response Rate
December 1, 2025

Soligenix Inc. (NASDAQ: SNGX) Reaches Key Enrollment Milestone in Phase 3 Trial with Encouraging Blinded Response Rate

  • The enrollment milestone represents a crucial step forward for the FLASH2 study, which builds upon the previous statistically significant Phase 3 FLASH study.
  • The promising early results are further corroborated by an ongoing investigator-initiated study being conducted at the University of Pennsylvania.
  • Soligenix is positioning itself to potentially deliver the first FDA-approved photodynamic therapy specifically indicated for CTCL.

In a pivotal advancement for patients suffering from a rare form of skin cancer, Soligenix (NASDAQ: SNGX) has achieved a critical clinical trial milestone that brings its investigational treatment significantly closer to potential FDA approval. The company announced that is has completed the planned enrollment of 50 patients necessary for the interim analysis in its 80-patient confirmatory Phase 3 clinical trial evaluating HyBryte(TM) (synthetic hypericin) for the treatment of cutaneous T-cell lymphoma (https://ibn.fm/ZeQoN).

The enrollment milestone represents a crucial step forward for the FLASH2 study, a randomized, double-blind, placebo-controlled clinical trial that builds upon the previous statistically significant Phase 3 FLASH study. What makes this announcement particularly noteworthy is not merely that the company has reached its enrollment target on schedule, but that the overall blinded study response rate to date stands at 48%, nearly double the anticipated 25% blinded response rate (based on a conservative response rate of 40% in the HyBryte arm and 10% in the placebo arm) that the study was designed to detect. This unexpected level of efficacy, combined with a benign safety profile consistent with prior studies, suggests that HyBryte may offer a meaningful treatment option for patients with limited alternatives.

“We are pleased to have reached this important milestone in patient enrollment consistent with our timelines for the FLASH2 study,” said Soligenix CEO and President Christopher J. Schaber, PhD. “With 50 patients enrolled, the planned interim analysis will occur in the second quarter of 2026. . . . We look forward to completing this study on schedule with topline results in the second half of 2026.”

The FLASH2 study was designed as a highly powered confirmatory trial with conservative assumptions, anticipating a 40% response rate in the HyBryte arm and a 10% response rate in the placebo arm through 18 weeks of continuous treatment. The current 48% overall blinded response rate exceeds these projections and exceeds the response rate observed in the original FLASH study, which used 18 weeks of interrupted treatment.

The promising early blinded results are further corroborated by an ongoing investigator-initiated study being conducted at the University of Pennsylvania. Dr. Ellen Kim, director of the Penn Cutaneous Lymphoma Program and lead investigator of the FLASH2 study, noted that HyBryte has demonstrated a response rate of 75% after 18 weeks of treatment in the open-label investigator study. Kim also emphasized that the benign safety profile observed in the first FLASH study and the ongoing investigator-initiated study continues to be seen in FLASH2.

Cutaneous T-cell lymphoma is a rare type of non-Hodgkin lymphoma that affects the skin, starting in blood cells called T-lymphocytes, which are white blood cells that form part of the immune system. The disease typically presents with red, scaly patches on the skin that can progress to raised plaques and tumors. CTCL affects approximately 31,000 individuals in the United States with approximately 3,200 new cases annually, and approximately 38,000 individuals in Europe with approximately 3,800 new cases annually. There is currently no cure for CTCL and no U.S. Food and Drug Administration (“FDA”)-approved first-line therapy specifically for the condition (https://ibn.fm/yAMgv). CTCL is a chronic disease, and patients repeat treatment periodically throughout their lives.

HyBryte represents a novel approach through photodynamic therapy that utilizes safe visible light rather than ultraviolet (“UV”) radiation. The treatment consists of a synthetically manufactured hypericin ointment combined with a precise dose of visible light. This fundamental difference potentially allows HyBryte to deliver therapeutic benefits without the cancer-causing risks associated with UV light exposure, addressing one of the most significant concerns with current phototherapy approaches that can increase the risk of skin cancers including melanoma.

The FLASH2 study design reflects lessons learned from the initial Phase 3 FLASH trial and incorporates input from both the FDA and the European Medicines Agency. The study is enrolling approximately 80 subjects with early-stage CTCL in a randomized, double-blind, placebo-controlled, multicenter format. The study’s Data Monitoring Committee is empowered to conduct one formal interim analysis when approximately 60% of the total patients have completed the primary endpoint evaluation. The treatment protocol extends the assessment period to 18 weeks of continuous treatment.

The significance of reaching the 50-patient enrollment milestone extends beyond the numerical achievement. This enrollment level triggers the planned interim analysis, which will be conducted by the independent Data Monitoring Committee (“DMC”) in the second quarter of 2026. The DMC’s review will help determine whether the trial should continue as planned or whether modifications might be warranted based on the emerging data. Notably, the FDA awarded an Orphan Products Development grant totaling $2.6 million over four years to the University of Pennsylvania to support an investigator-initiated study evaluating HyBryte for expanded treatment in patients with early-stage CTCL, including in the home-use setting.

As Soligenix moves forward with the FLASH2 trial toward the planned interim analysis in the second quarter of 2026 and topline results in the second half of 2026, the company is positioning itself to potentially deliver the first FDA-approved photodynamic therapy specifically indicated for CTCL. The company has stated that successful completion of the second Phase 3 study will support regulatory approval applications for potential commercialization worldwide. For the approximately 31,000 Americans living with CTCL, the progression of HyBryte through clinical development represents hope for a treatment that could potentially offer efficacy without the cumulative toxicities and cancer risks associated with some existing therapies.

For more information, visit www.Soligenix.com.

NOTE TO INVESTORS: The latest news and updates relating to SNGX are available in the company’s newsroom at https://ibn.fm/SNGX

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