Soligenix Extends Enrollment in Phase 3 Trial of SGX301 in Cutaneous T-cell Lymphoma

Soligenix Extends Enrollment in Phase 3 Trial of SGX301 in Cutaneous T-cell Lymphoma

The pivotal Phase 3 trial testing Soligenix‘s SGX301 will recruit an additional 40 subjects with cutaneous T-cell lymphoma — a kind of lymphoma of the skin — after a positive recommendation from an independent Data Monitoring Committee (DMC).

The recommendation comes after a first interim analysis including approximately 100 patients. It showed that SGX301 has the potential to improve patient outcomes, but that a significant difference might only be seen if more patients are included in the trial. The study will now include 160 patients.

“We are pleased to have received the DMC’s recommendation to continue enrolling to the adjusted target of 160 evaluable subjects in order to maintain our conservative power calculation,” Christopher J. Schaber, PhD, president and chief executive officer of Soligenix, said in a press release. “It is gratifying to have received this feedback from the DMC indicating sufficient potential efficacy to warrant enrolling additional subjects into the trial.”

SGX301 is a photodynamic therapy, meaning it uses light-sensitive medication and a light source to destroy abnormal cells. The treatment consists of a synthetic form of the potent photosensitizer hypericin, which is applied as a topical cell in the cancerous skin lesions and activated using a brief treatment with light.

But unlike other photodynamic approaches, which use ultraviolet light that might cause melanoma and other secondary cancers, Soligenix uses a safe, fluorescent light.

The approach has been tested in a Phase 2 trial, where it induced a significant response in 58.3% of patients, compared to 8.3% of those taking a placebo. Responses were defined as a 50% reduction or more in skin lesions after six weeks of treatment.

The findings led Soligenix to design FLASH(NCT02448381), a larger Phase 3 trial testing SGX301 in patients with mycosis fungoides, a kind of cutaneous T-cell lymphoma, with at least three skin lesions.

The trial is evaluating SGX301 in three treatment cycles. Each lasts eight weeks, but patients only receive treatment in the first six weeks of every cycle. A response is determined at the end of week 8.

In cycle 1, patients will receive either the investigational medicine or a placebo twice weekly. For every patient receiving a placebo, two will be assigned SGX301.

Then, in cycle 2, all patients receive SGX301 in their index (largest) lesions. In a third, optional cycle, all patients receive SGX301 in all their lesions.

After completing the treatment, all trial participants will be followed for an additional six months.

The study’s main goal is to determine the proportion of patients achieving an overall 50% or higher reduction in their treated lesions at the end of cycle 1. Secondary measures include duration of responses, degree of improvement, time until relapse, and safety.

“We believe SGX301 has the potential to be a valuable therapy in the treatment of early stage CTCL, which is an orphan disease and area of unmet medical need,” said Schaber.

“Given our current enrollment status of approximately 120 subjects, we anticipate completing the study before the end of 2019 with topline results coming no later than the first quarter of 2020,” he added.

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