US-based biotechnology company Soligenix has begun enrolling subjects in its double-blind, multi-centre Phase III trial of HyBryte (synthetic hypericin), a first-in-class photodynamic therapy for cutaneous T-cell lymphoma (CTCL).

Fluorescent Light Activated Synthetic Hypericin 2 (FLASH2) is a confirmatory trial that builds on the outcomes of the initial Phase III FLASH study.

The randomised, placebo-controlled FLASH2 trial is expected to enrol nearly 80 patients with early-stage CTCL.

Its design mirrors the previous Phase III FLASH study, which consisted of three six-week treatment cycles, with the assessment of primary efficacy at the end of the first six-week cycle.

FLASH2 will extend this assessment to an 18-week period of continuous treatment without breaks, with the primary endpoint assessment at the end of this period.

In the initial Phase III study, a 49% rate of treatment response was found in subjects who completed 18 weeks of treatment.

All critical clinical study design components from the first FLASH study have been retained for FLASH2, including the primary endpoint and key inclusion-exclusion criteria.

The FLASH2 trial’s extended treatment duration aims to statistically prove the effectiveness of HyBryte over a more extended, ‘real-world’ treatment course.

Also known as SGX301, HyBryte is a first-in-class photodynamic therapy activated through the use of safe, visible light.

Soligenix CEO and president Christopher Schaber said: “We are pleased to be initiating patient enrolment into our FLASH2 study.

“FLASH2 is expected to enrol patients in the US and Europe, with a formal interim analysis anticipated early in 2026.

“Given the extensive engagement with the CTCL community, the esteemed Medical Advisory Boards in the US and Europe, key patient advocacy groups like the Cutaneous Lymphoma Foundation, as well as our previous trial experience with this disease, accelerated enrolment in support of this study is anticipated.

“We look forward to providing periodic updates on the trial’s progress in 2025.”