Soligenix Announces Initiation of Pivotal Phase III Clinical Trial

Soligenix, Inc. recently announced that patient enrollment has been opened for its Phase III, 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 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 III 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 I clinical study in healthy volunteers. In a Phase II, 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,” said 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 III 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 III trial marks an important step in the development of SGX301 as a treatment for CTCL,” added 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 II study of SGX301, the Phase III 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 (ie, 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.

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, which 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.

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 II 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 FDA, as well as orphan designation from the European Medicines Agency (EMA).

Soligenix is a late-stage biopharmaceutical company focused on developing and commercializing products to treat rare diseases in which 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 more information, visit www.soligenix.com.