PRISM MarketView Highlights Soligenix’s Promising HyBryte™ Replication Trial: Setting the Stage for Success

Chronic Cancer, Key Achievements and the Pathway to Regulatory Success

The late-stage biopharmaceutical company, Soligenix, Inc. (Nasdaq: SNGX), is working to address a critical gap in treatment of rare and chronic cancer, cutaneous T-cell lymphoma (CTCL). CTCL is a cancer of the white blood cells, called T-cells, which are an integral part of the immune system. These T-cells develop abnormalities that cause them to attack the skin, resulting in dry, scaly patches and skin lesions. CTCL currently has no cure. The disease affects approximately 31,000 individuals in the U.S. and 38,000 in Europe, with approximately 4,000 new cases annually. Soligenix is targeting a CTCL therapeutics market that reached a value of $520 million in 2023 with its lead product candidate, HyBryte™ (synthetic hypericin).

Soligenix has received regulatory validation of the unmet medical need that currently exists in this rare disease, with the granting of Orphan Drug Designation and Fast Track Status by the U.S. Food and Drug Administration (FDA), and Orphan Designation by the European Medicines Agency (EMA) for HyBryte™ in the treatment of early-stage CTCL. In April 2024, Soligenix announced that it had received agreement from the EMA on the key design components of a confirmatory Phase 3 placebo-controlled study called FLASH2. This targeted replication study is expected to enroll approximately 80 patients in the U.S. and Europe, beginning by the end of 2024, with top-line results anticipated in the second half of 2026. FLASH2 is expected to have a high probability of success with a larger magnitude of response and should enroll more rapidly due to Soligenix’s significant experience with U.S. CTCL clinical sites and its ability to potentially enroll patients from the first FLASH study.

A New Benchmark in CTCL Treatment

In 2022, Soligenix successfully completed its positive Phase 3 FLASH (Fluorescent Light Activated Synthetic Hypericin) study in the treatment of early-stage CTCL. The results of the study were published in the peer-reviewed Journal of the American Medical Association (JAMA) Dermatology and celebrated by the trial’s investigators and patient advocacy groups such as the Cutaneous Lymphoma Foundation.

Richard Straube, MD, Senior Vice President and Chief Medical Officer of Soligenix, stated in 2022, “In treating CTCL, which is a chronic cancer with no cure, long-term safety is of paramount concern. Most current treatment options for CTCL are associated with significant safety concerns, including black-box warnings. HyBryte™ treatment has demonstrated strong and rapid efficacy with a very benign safety profile. This is of significant benefit to patients living with this difficult disease. The substantial increase in efficacy with longer treatment and the similar performance against both patch and plaque lesions are particularly encouraging. As one of the largest studies in CTCL, this study and this publication establishes a new benchmark in CTCL treatment.”

Positive Clinical Results

Soligenix subsequently completed an open-label study in nine patients who received HyBryte™ treatment of their cancerous lesions over an eight-week period. Results in individual lesions showed that 7 of the 27 index lesions (25.9%) had at least a 50% improvement in their modified Composite Assessment of Index Lesion Severity (mCAILS) score and 4 of the 27 index lesions (14.8%) were completely resolved after as little as eight weeks of twice a week HyBryte™ treatment. The study’s results, which were recently published in the prestigious Journal of the European Academy of Dermatology & Venereology, confirmed the results of Soligenix’s Phase 3 FLASH trial.

Discussing the study’s results, Brian Poligone, MD, PhD, Director of the Rochester Skin Lymphoma Medical Group, Fairport, NY, and Principal Investigator for the compatibility study and Leading Enrolling Investigator in the FLASH study, said, “We were excited for the opportunity to work with Soligenix and make HyBryte™ available to our patients. Since the completion of the Phase 3 FLASH study, I have had a number of patients asking about possible access to this promising therapy. Fortunately, we were chosen to conduct this study and the patients’ enthusiasm for the product was evident by their willingness to participate in the trial, allowing for its rapid completion. I look forward to continuing to work with Soligenix to further advance the HyBryte™ program so my patients can have this much needed treatment option available to them.”

FDA Grant Award Supports Clinical Development

In addition, Soligenix has opened patient enrollment in an investigator-initiated study (IIS) at the University of Pennsylvania, supported by a $2.6 million Orphan Products Development grant award by the FDA.

The trial is sponsored by Ellen Kim, MD, Director, Penn Cutaneous Lymphoma Program, Vice Chair of Clinical Operations, Dermatology Department, and Professor of Dermatology at the Hospital of the University of Pennsylvania. Dr. Kim was also a leading enroller in the company’s positive Phase 3 FLASH (Fluorescent Light Activated Synthetic Hypericin) study in the treatment of early-stage CTCL.

Dr. Kim said in a statement, “In the Phase 3 FLASH study, HyBryte™ was shown to be efficacious with a promising safety profile. CTCL patients are often searching for alternative treatments, with limited options especially for early-stage disease. HyBryte™ offers a distinct treatment option which patients found extremely useful and continue to specifically request. We look forward to demonstrating the expanded use of HyBryte™ in a “real world” setting and thank both the FDA and Soligenix for their support of this study.”

Pivotal Confirmatory Trial

Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix, says that the corporate objectives for the continued studies were to reinforce and replicate the positive HyBryte™ data from the FLASH study. Dr. Schaber commented, “We look forward to continuing to work with Dr. Poligone and all of our committed clinical investigators to make HyBryte™ available to this underserved orphan patient population.”

Soligenix’s targeted replication study, FLASH2, is expected to begin enrolling patients in the U.S. and Europe by the end of 2024.

In a recent discussion, Dr. Schaber highlighted, “The confirmatory Phase 3 FLASH2 study that is required for potential worldwide approval is a highly statistically powered replication study of the first positive FLASH trial.  All key design parameters remain essentially the same, including the primary endpoint; however, an important design modification to highlight in the FLASH2 trial is that we will be treating, more “real world”, twice a week for 18 continuous weeks versus the three 6 week stop and start cycles (18 weeks total) that were utilized in the first FLASH study.

“We anticipate that this has the potential to further strengthen the positive response rates already demonstrated across multiple clinical trials with HyBryte™.  Given the shorter time to potential commercial revenue with the EMA agreed to trial design and its similarity to the first FLASH study, we are excited to initiate this confirmatory 80 patient trial. At the same time, we will continue our collaborative discussions with the FDA on potential ways to modify the development path and data package to adequately address their feedback.”

About Soligenix, Inc.

Soligenix is a late-stage biopharmaceutical company focused on developing and commercializing products to treat rare diseases where there is an unmet medical need. Our Specialized BioTherapeutics business segment is developing and moving toward potential commercialization of HyBryte™ (SGX301 or synthetic hypericin sodium) as a novel photodynamic therapy utilizing safe visible light for the treatment of cutaneous T-cell lymphoma (CTCL). With successful completion of the second Phase 3 study, regulatory approvals will be sought to support potential commercialization worldwide. Development programs in this business segment also include expansion of synthetic hypericin (SGX302) into psoriasis, our first-in-class innate defense regulator (IDR) technology, dusquetide (SGX942) for the treatment of inflammatory diseases, including oral mucositis in head and neck cancer, and (SGX945) in Behçet’s Disease.

Our Public Health Solutions business segment includes development programs for RiVax®, our ricin toxin vaccine candidate, as well as our vaccine programs targeting filoviruses (such as Marburg and Ebola) and CiVax™, our vaccine candidate for the prevention of COVID-19 (caused by SARS-CoV-2). The development of our vaccine programs incorporates the use of our proprietary heat stabilization platform technology, known as ThermoVax®. To date, this business segment has been supported with government grant and contract funding from the National Institute of Allergy and Infectious Diseases (NIAID), the Defense Threat Reduction Agency (DTRA) and the Biomedical Advanced Research and Development Authority (BARDA).

For further information regarding Soligenix, Inc., please visit the Company’s website at and follow us on LinkedIn and Twitter at @Soligenix_Inc.

Forward Looking Statements

This article may contain forward-looking statements that reflect Soligenix’s current expectations about its future results, performance, prospects and opportunities, including but not limited to, potential market sizes, patient populations, clinical trial enrollment, the expected timing for closing the offering described herein and the intended use of proceeds therefrom. Statements that are not historical facts, such as “anticipates,” “estimates,” “believes,” “hopes,” “intends,” “plans,” “expects,” “goal,” “may,” “suggest,” “will,” “potential,” or similar expressions, are forward-looking statements. These statements are subject to a number of risks, uncertainties and other factors that could cause actual events or results in future periods to differ materially from what is expressed in, or implied by, these statements, and include the expected amount and use of proceeds from the offering and the expected closing date of the offering. Soligenix cannot assure you that it will be able to successfully develop, achieve regulatory approval for or commercialize products based on its technologies, particularly in light of the significant uncertainty inherent in developing therapeutics and vaccines against bioterror threats, conducting preclinical and clinical trials of therapeutics and vaccines, obtaining regulatory approvals and manufacturing therapeutics and vaccines, that product development and commercialization efforts will not be reduced or discontinued due to difficulties or delays in clinical trials or due to lack of progress or positive results from research and development efforts, that it will be able to successfully obtain any further funding to support product development and commercialization efforts, including grants and awards, maintain its existing grants which are subject to performance requirements, enter into any biodefense procurement contracts with the U.S. Government or other countries, that it will be able to compete with larger and better financed competitors in the biotechnology industry, that changes in health care practice, third party reimbursement limitations and Federal and/or state health care reform initiatives will not negatively affect its business, or that the U.S. Congress may not pass any legislation that would provide additional funding for the Project BioShield program. In addition, there can be no assurance as to the timing or success of any of its clinical/preclinical trials. Despite the statistically significant result achieved in the first HyBryte™ (SGX301) Phase 3 clinical trial for the treatment of cutaneous T-cell lymphoma, there can be no assurance that the second HyBryte™ (SGX301) Phase 3 clinical trial will be successful or that a marketing authorization from the FDA or EMA will be granted. Additionally, although the EMA has agreed to the key design components of the second HyBryte™ (SGX301) Phase 3 clinical trial, no assurance can be given that the Company will be able to modify the development path to adequately address the FDA’s concerns or that the FDA will not require a longer duration comparative study. Notwithstanding the result in the first HyBryte™ (SGX301) Phase 3 clinical trial for the treatment of cutaneous T-cell lymphoma and the Phase 2a clinical trial of SGX302 for the treatment of psoriasis, there can be no assurance as to the timing or success of the clinical trials of SGX302 for the treatment of psoriasis. Further, there can be no assurance that RiVax® will qualify for a biodefense Priority Review Voucher (PRV) or that the prior sales of PRVs will be indicative of any potential sales price for a PRV for RiVax®. Also, no assurance can be provided that the Company will receive or continue to receive non-dilutive government funding from grants and contracts that have been or may be awarded or for which the Company will apply in the future. These and other risk factors are described from time to time in filings with the Securities and Exchange Commission (the “SEC”), including, but not limited to, Soligenix’s reports on Forms 10-Q and 10-K. Unless required by law, Soligenix assumes no obligation to update or revise any forward-looking statements as a result of new information or future events.


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PRISM MarketView Highlights Soligenix’s Promising HyBryte™ Replication Trial: Setting the Stage for Success

Catie Corcoran

Biotech Editor