Soligenix Announces Initiation of its Pivotal Phase 3 Clinical Trial of SGX301 (Synthetic Hypericin) for the Treatment of Cutaneous T-Cell Lymphoma

Princeton, NJ – December 14, 2015 – Soligenix, Inc. (OTCQB: SNGX) (Soligenix or the Company), a late-stage biopharmaceutical company focused on developing and commercializing products to treat rare diseases where there is an unmet medical need, announced today that patient enrollment has been opened for its Phase 3, multicenter, randomized, double-blind, placebo-controlled study evaluating SGX301 (synthetic hypericin), as a treatment for cutaneous T-cell lymphoma (CTCL). SGX301 has previously been granted both orphan drug and fast track designations from the US Food and Drug Administration (FDA) for the first-line treatment of CTCL, a rare disease and a class of non-Hodgkin’s lymphoma, a type of cancer of the white blood cells that are an integral part of the immune system.

Soligenix has been working with leading CTCL centers, as well as with the National Organization for Rare Disorders (NORD) and the Cutaneous Lymphoma Foundation (CLF) to initiate this pivotal Phase 3 clinical trial with SGX301, referred to as the FLASH study (Fluorescent Light Activated Synthetic Hypericin), that will enroll 120 evaluable subjects.

SGX301 is a novel, first-in-class, photodynamic therapy that combines synthetic hypericin, a potent photosensitizer that is applied to the cancerous skin lesions and activated using a brief safe, fluorescent light treatment. This treatment approach avoids the risk of secondary malignancies (including melanoma) inherent with the frequently employed DNA-damaging chemotherapeutic drugs and other photodynamic therapies that are dependent on ultraviolet exposure. Topical hypericin has demonstrated safety in a Phase 1 clinical study in healthy volunteers. In a Phase 2, double-blind, placebo-controlled clinical study in CTCL patients, the drug was safe and well tolerated, with 58.3% of the CTCL patients responding to SGX301 treatment compared to only 8.3% receiving placebo (p ≤ 0.04).

“I enthusiastically support Soligenix in their efforts to improve outcomes for patients with CTCL, affecting up to 50,000 patients in the US,” stated Alain Rook, MD, Director, Cutaneous Lymphoma Program, Hospital of the University of Pennsylvania. “I have been working closely with the Soligenix team on this Phase 3 clinical program and I am pleased it is now open to enroll patients. I believe that SGX301 has the potential to be a major step forward in the treatment of CTCL by providing a safer alternative therapy over the course of the patients’ disease than is currently available.”

“The initiation of the Phase 3 trial marks an important step in the development of SGX301 as a treatment for CTCL,” stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix. “We are excited to be working with many experienced clinicians as well as with NORD and CLF, as we look to enroll in this pivotal study in an effort to address the significant unmet medical need in this orphan disease.”

Based on the positive results demonstrated in the Phase 2 study of SGX301, the Phase 3 protocol will be a highly powered, double-blind, randomized, placebo-controlled, multicenter trial and will seek to enroll 120 evaluable subjects. The trial will consist of three treatment cycles, each of 8 weeks duration. Treatments will be administered twice weekly for the first 6 weeks and treatment response will be determined at the end of Week 8. In the first treatment cycle, approximately 80 subjects will receive SGX301 and 40 will receive placebo treatment of their index lesions. In the second cycle, all subjects will receive SGX301 treatment of their index lesions and in the third cycle all subjects will receive SGX301 treatment of all their lesions. Subjects will be followed for an additional 6 months after the completion of treatment. The primary efficacy endpoint will be assessed on the percent of patients in each of the two treatment groups (i.e., SGX301 and placebo) achieving a Partial or Complete Response (yes/no) of the treated lesions defined as a ≥ 50% reduction in the total Composite Assessment of Index Lesion Disease Severity (CAILS) score for 3 index lesions at the Cycle 1 evaluation visit (Week 8) compared to the total CAILS score at baseline. Other secondary measures will assess treatment response (including duration), degree of improvement, time to relapse and safety. The study is anticipated to complete enrollment with primary data available in the second half of 2016.

About Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is a class of non-Hodgkin’s lymphoma (NHL), a type of cancer of the white blood cells that are an integral part of the immune system. Unlike most NHLs which generally involve B-cell lymphocytes (involved in producing antibodies), CTCL is caused by an expansion of malignant T-cell lymphocytes (involved in cell-mediated immunity) normally programmed to migrate to the skin. These malignant cells migrate to the skin, causing various lesions to appear that may change shape as the disease progresses, typically beginning as a rash and eventually forming plaques and tumors. Mortality is related to the stage of CTCL, with median survival generally ranging from about 12 years in the early stages to only 2.5 years when the disease has advanced. There is currently no cure for CTCL.

CTCL constitutes a rare group of NHLs, occurring in about 4% of the approximate 500,000 individuals living with the disease. It is estimated, based upon review of historic published studies and reports and an interpolation of data on the incidence of CTCL that it affects over 20,000 individuals in the US, with approximately 2,800 new cases seen annually.

About SGX301

SGX301 is a novel first-in-class photodynamic therapy utilizing safe visible light for activation. The active ingredient in SGX301 is synthetic hypericin, a potent photosensitizer that is topically applied to skin lesions and then activated by fluorescent light 16 to 24 hours later. This treatment approach avoids the risk of secondary malignancies (including melanoma) inherent with the frequently employed DNA-damaging chemotherapeutic drugs and other photodynamic therapies that are dependent on ultraviolet exposure. Combined with photoactivation, hypericin has demonstrated significant anti-proliferative effects on activated normal human lymphoid cells and inhibited growth of malignant T-cells isolated from CTCL patients. In a published Phase 2 clinical study in CTCL, patients experienced a statistically significant (p ≤ 0.04) improvement with topical hypericin treatment whereas the placebo was ineffective: 58.3% compared to 8.3%, respectively. SGX301 has received orphan drug and fast track designations from the US Food and Drug Administration (FDA), as well as orphan designation from the European Medicines Agency (EMA).

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 BioTherapeutics business segment is developing SGX301 as a first-in-class photodynamic therapy utilizing safe visible light for the treatment of cutaneous T-cell lymphoma, proprietary formulations of oral beclomethasone 17,21-dipropionate (BDP) for the prevention/treatment of gastrointestinal (GI) disorders characterized by severe inflammation including pediatric Crohn’s disease (SGX203) and acute radiation enteritis (SGX201), and our novel innate defense regulator technology (SGX942) for the treatment of oral mucositis.

Our Vaccines/BioDefense business segment includes active development programs for RiVax™, our ricin toxin vaccine candidate, VeloThrax®, our anthrax vaccine candidate, OrbeShield™, our GI acute radiation syndrome therapeutic candidate and SGX943, our melioidosis therapeutic candidate. The development of our vaccine programs incorporates the use of our proprietary heat stabilization platform technology, known as ThermoVax®. Currently, this business segment is supported with up to $57 million in government grant and contract funding from the National Institute of Allergy and Infectious Diseases (NIAID) and the Biomedical Advanced Research and Development Authority (BARDA).

For further information regarding Soligenix, Inc., please visit the Company’s website at www.soligenix.com.

This press release may contain forward-looking statements that reflect Soligenix, Inc.’s current expectations about its future results, performance, prospects and opportunities, including but not limited to, potential market sizes, patient populations and clinical trial enrollment. Statements that are not historical facts, such as “anticipates,” “estimates,” “believes,” “intends,” “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. 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 vaccines against bioterror threats conducting preclinical and clinical trials of vaccines, obtaining regulatory approvals and manufacturing 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 US 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 US Congress may not pass any legislation that would provide additional funding for the Project BioShield program. These and other risk factors are described from time to time in filings with the Securities and Exchange Commission, 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.