Novel Photodynamic Therapy Active in CTCL


Treatment with SGX301 led to statistically significant responses in patients with cutaneous T-cell lymphoma, according to preliminary top-line results from the pivotal phase III FLASH trial released by Soligenix.

Treatment with SGX301 led to statistically significant responses in patients with cutaneous T-cell lymphoma (CTCL), according to preliminary top-line results from the pivotal phase III FLASH trial released by Soligenix.

Compared with placebo, SGX301 induced improved responses in terms of the Composite Assessment of Index Lesion Score (CAILS) at 8 weeks during the first cycle of treatment (P= .04), which was the trial’s primary end point. A more robust response rate was also seen with SGX301 over placebo in a preliminary assessment of the second cycle of treatment.

"This is an important outcome for patients suffering from CTCL. SGX301 has successfully demonstrated efficacy in this challenging chronic cancer, with no safety concerns, making it a potentially preferred first-line option for the treatment of early-stage CTCL, which is the large majority of patients suffering from this disease," lead investigator Ellen Kim, MD, said in a press release. "The treatment showed a statistically significant improvement after just 6 weeks of treatment. This successfully proves that the drug has biologic activity in combating this disease in a relatively short time window, with preliminary data suggesting that the improvement continues to increase with extended treatment.”

“In addition to the efficacy demonstrated, SGX301 was well-tolerated and its mechanism of action is not associated with DNA damage like other currently available therapies," added Kim, who is the director of the Dermatology Clinic, Perelman Center for Advanced Medicine.

SGX301 is a first-in-class photodynamic treatment with an active ingredient of synthetic hypericin that is applied topically and then activated using fluorescent light after 16 to 24 hours.

FLASH (Fluorescent Light Activated Synthetic Hypericin) is a multicenter, randomized, double-blind, placebo-controlled phase III study exploring the use of SGX301 in patients with patch/plaque phase CTCL (NCT02448381). The trial enrolled 169 patients with stage IA-IIA CTCL and at least 3 evaluable lesions who were randomized 2:1 to receive either SGX301 or placebo. Anyone with a history of sun hypersensitivity, unhealed sunburn, a history of systemic immunosuppression or a patient receiving topical or systemic steroids or an investigational agent was excluded from the trial. Of the enrolled patients, 166 were included in the preliminary analysis.

Patients were treated in 3 eight-week cycles with SGX301 (n = 116) or placebo (n = 50) administered twice daily for the first 6 weeks of each cycle.

In the first cycle, 16% of patients in the SGX301 arm achieved ≥50% reduction of their lesions, as measured by CAILS score, compared with 4% in the placebo arm. SGX301 was found to be well tolerated in this cycle.

All patients received SGX301 in the second cycle and preliminary results suggested a response rate of at least 35% with responses continuing with further treatment. Further results from cycle 2 are expected to be released in June 2020.

The third cycle includes optional treatment with SGX301 followed by 6 months of follow-up and the majority of patients enrolled in the study have so far elected to continue with the optional treatment.

A ≥50% reduction in 3 treated lesions as defined by CAILS score is the primary end point of the trial with secondary end points included complete response rate, degree of improvement of the 3 lesions, duration of response, time to relapse, and safety.

"We are extremely pleased with the results, which demonstrate successful treatment with SGX301 and reinforces its potential to be an important new treatment for early stage CTCL. We will now look to move as quickly as possible to complete a full analysis of the data for publication, as well as begin preparations for a robust discussion with the FDA regarding this important dataset," Christopher J. Schaber, PhD, president and CEO of Soligenix, said in a statement.

He also noted that the company is preparing for a new drug application submission to the FDA for SGX301. “These results support our long-standing belief that 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."

In 2015, the FDA granted a fast track designation to SGX301 for the treatment of patients with CTCL. The agent also previously received an orphan drug designation.


Soligenix Announces Positive Top-line Results for its Pivotal Phase 3 FLASH Trial Evaluating SGX301 in Treatment of Cutaneous T-Cell Lymphoma [news release]. Princeton, NJ: Soligenix, Inc; March 19, 2020. Accessed March 19, 2020.

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