Continued optional treatment with Soligenix, Inc.’s SGX301 (synthetic hypericin) demonstrates positive benefits in patients with cutaneous T-Cell lymphoma

Nearly half of all patients in Phase 3 FLASH (Fluorescent Light Activated Synthetic Hypericin) trial continue to see sustained and statistically significant improvement in their response rates when treated with SGX301 through 18 weeks (Cycle 3), reinforcing positive SGX301 primary endpoint treatment response, the company reports.

This data reinforces the positive SGX301 primary endpoint treatment response demonstrated in Cycle 1. SGX30l treatment in Cycle 3 further improved response rates, with 49 percent of patients electing to receive SGX301 for a total of 18 weeks demonstrating a 50 percent or greater reduction in their combined CAILS (Composite Assessment of Index Lesion Score) lesion score compared to 40 percent of patients demonstrating such a reduction after completing 12 weeks of SGX301 treatment in Cycle 2 (p=0.046).  

In addition, continued analysis of results from the protocol mandated efficacy cycles (Cycles 1 and 2) of the study has revealed that 12 weeks of treatment (Cycle 2) with SGX301 is equally effective on both patch (response 37%, p=0.0009) and plaque (response 42%, p<0.0001) lesions of cutaneous T-cell lymphoma (CTCL) when compared to Cycle 1 placebo lesion responses, further demonstrating the unique benefits of the more deeply penetrating visible light activation of hypericin. 

SGX301 continued to be very well tolerated, benefiting from the lack of hypericin circulation in the blood stream after targeted topical application to the lesions, as well as the use of visible light. 

"Along with SGX301's rapid response time and safety profile, the patch and plaque data from the study are extremely compelling," says Brian Poligone, MD, PhD, Lead Enrolling Investigator in the FLASH study and Director of the Rochester Skin Lymphoma Medical Group, Fairport, NY, USA, in a news release.  "Current treatments for CTCL are generally less effective against plaques and deeper lesions, very similar to the problem observed in psoriasis.  The ability of SGX301 to target both patches and thicker plaques in CTCL is an important feature for this therapy and, if approved, will be of benefit to patients, regardless of their presentation.  These results are consistent with the positive findings highlighted in a recently reported case study of folliculotropic mycosis fungoides, a hard to treat variant of CTCL where lesions are associated with the hair follicles deep in the skin and more resistant to phototherapy."

"In treating CTCL, which is a chronic cancer with no cure, long-term safety is of paramount concern.  SGX301 treatment continues to demonstrate strong efficacy and a very benign safety profile, which is of significant benefit to patients living with this difficult disease,” adds Richard Straube, MD, Chief Medical Officer of Soligenix.   “Although the focus of the additional optional cycle was safety, we continue to see improvement in CTCL lesions with extended SGX301 treatment, building upon the robust efficacy signal in previous cycles.  The efficacy against both patch and plaque lesions, for example, is particularly encouraging and we believe provides another important differentiating feature from other therapies currently being used to treat early stage disease." 

"These results continue to strengthen our long-standing belief that SGX301 has the potential to be a valuable and life-changing therapy for patients suffering from CTCL, which is an orphan disease and area of unmet medical need," says Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix.  "With the study now concluding, we continue to thoroughly assess commercialization and/or partnership of SGX301 while in parallel preparing for filing the New Drug Application with FDA.  Despite the challenges imposed by the COVID-19 pandemic, 2020 continues to be a very impactful year for us as we now focus on our next near-term and potentially transformational catalyst - the announcement of top-line final results by year-end from our other pivotal Phase 3 study of SGX942 (dusquetide) for the treatment of oral mucositis in head and neck cancer patients."

Soligenix previously announced positive top-line results when the FLASH study achieved statistical significance (p=0.04) in its primary endpoint over the first 6-week double-blind treatment cycle (Cycle 1) (available here).  The study enrolled 169 patients randomized 2:1 to receive either SGX301 or placebo in Cycle 1.  After the subsequent additional 6-week treatment in the open-label Cycle 2, the response rate in patients receiving a total of 12 weeks treatment increased two and a half-fold (40% with p<0.0001 compared to placebo and p<0.0001 compared to 6-weeks treatment).  These highly statistically significant results confirm the benefit of continued SGX301 treatment in CTCL patients (press release available here).  Treatment responses were assessed at Week 8 (after 6 weeks of treatment) and at Week 16 (after 12 weeks of treatment).  A positive response was defined as an improvement of at least 50 percent  in the CAILS for three index lesions evaluated.  Further analysis of the patients receiving SGX301 through 12 weeks has revealed that treatment of both patch and plaque lesions was equally effective.  Similar to the overall findings, the responses of individual lesions were statistically significantly improved after 12 weeks treatment relative to 6 weeks treatment with SGX301 or placebo.  Importantly, this improvement was seen equally for both patches (response 37%, p=0.0009) and plaques (response 42%, p<0.0001), a differentiating feature of SGX301 relative to other treatment modalities in CTCL.

Cycle 3 of the study was designed as a compassionate use, optional, cycle where patients could elect to continue SGX301 treatment for an additional 6 weeks (up to a total of 18 weeks) for all their lesions.  Sixty-six percent (66%) of patients elected to continue into Cycle 3.  During this cycle, SGX301 was applied to multiple cancerous skin lesions on the body, maximizing the exposure to the drug.  Including Cycle 3 in the study enabled a more rigorous safety assessment in the context of extended and increased exposure to SGX301.  Similar to the overall findings, the responses of individual lesions after three cycles of treatment with SGX301 was statistically significant after Cycle 3 relative to outcomes after Cycles 1 and 2 (49% of all lesions responded with a CAILS score reduction of at least 50%, with a statistically significant change from end of Cycle 2 [p=0.0009] and compared to patients receiving placebo only in Cycle 1 [p<0.0001]).  Further, no synthetic hypericin was detected in the bloodstream of patients, minimizing safety concerns of drug effects outside of the tumor area. All safety data continues to indicate that SGX301 treatment is safe and well tolerated, in marked contrast to other available second-line and off-label therapies for CTCL.