On May 4, 2023 Soligenix, Inc. (Nasdaq: 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, reported positive clinical results from a compatibility study evaluating HyBryte (synthetic hypericin sodium) in the treatment of cutaneous T-cell lymphoma (CTCL) using the commercially ready Daavlin Series 7 visible light device, which recently received 510(k) clearance from U.S. Food and Drug Administration (FDA) (Press release, Soligenix, MAY 4, 2023, View Source [SID1234631055]). The open-label study (protocol HPN-CTCL-02) enrolled 9 patients to receive 8 weeks of HyBryte treatment of their cancerous lesions, with an assessment of treatment response conducted at week 10 using the Composite Assessment of Index Lesion Severity (CAILS) score. All subjects were enrolled by Brian Poligone, MD, PhD, at the Rochester Skin Lymphoma Medical Group.
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The purpose of the study was to establish that any light device capable of producing visible light of an appropriate and consistent wavelength (500 to 650 nm) was suitable for use with HyBryte and extend the pharmacokinetic profile using a recently developed, more sensitive hypericin assay. In addition to meeting these objectives, the efficacy demonstrated strongly substantiates the results of the Phase 3 FLASH (Fluorescent Light Activated Synthetic Hypericin) study. The treatment response data of 22% following 8 weeks of twice weekly HyBryte therapy recapitulates the results of the FLASH trial, despite the fact that patients in the current study were specifically selected to have more extensive disease consistent with its potential commercial use. Additionally, in this study all patients had improvements in their cumulative CAILS score (average improvement of 36.4%, range 8 to 100%). Results in individual lesions showed that 7 of the 27 index lesions (25.9%) had at least a 50% improvement in their CAILS score and 4 of the 27 index lesions (14.8%) were completely resolved after as little as 8 weeks of treatment. Other key evaluations included measurements of systemic exposure and cardiac output, which yielded extremely low and limited levels of systemic hypericin (plateau concentration of approximately 0.00013 μg/mL) detected in the blood and no observable impact to normal sinus rhythm, reinforcing the safety of HyBryte.
"We were excited for the opportunity to work with Soligenix and make HyBryte available to our patients," stated 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. "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."
"These results reinforce the positive HyBryte data from the FLASH study. Important corporate objectives for the study were to replicate results previously observed in the FLASH study, while using finished drug product manufactured by our proposed commercial contract manufacturer and activated using a commercially viable light device," stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix. "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."
About HyBryte
HyBryte (research name SGX301) is a novel, first-in-class, photodynamic therapy utilizing safe, visible light for activation. The active ingredient in HyBryte is synthetic hypericin, a potent photosensitizer that is topically applied to skin lesions that is taken up by the malignant T-cells, and then activated by visible light approximately 24 hours later. The use of visible light in the red-yellow spectrum has the advantage of penetrating more deeply into the skin (much more so than ultraviolet light) and therefore potentially treating deeper skin disease and thicker plaques and lesions. This treatment approach avoids the risk of secondary malignancies (including melanoma) inherent with the frequently employed DNA-damaging drugs and other phototherapy 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. HyBryte has received orphan drug and fast track designations from the FDA, as well as orphan designation from the European Medicines Agency (EMA).
The recently published Phase 3 FLASH trial enrolled a total of 169 patients (166 evaluable) with Stage IA, IB or IIA CTCL. The trial consisted of three treatment cycles. Treatments were administered twice weekly for the first 6 weeks and treatment response was determined at the end of the 8th week of each cycle. In the first double-blind treatment cycle, 116 patients received HyBryte treatment (0.25% synthetic hypericin) and 50 received placebo treatment of their index lesions. A total of 16% of the patients receiving HyBryte achieved at least a 50% reduction in their lesions (graded using a standard measurement of dermatologic lesions, the CAILS score) compared to only 4% of patients in the placebo group at 8 weeks (p=0.04) during the first treatment cycle (primary endpoint). HyBryte treatment in the first cycle was safe and well tolerated.
In the second open-label treatment cycle (Cycle 2), all patients received HyBryte treatment of their index lesions. Evaluation of 155 patients in this cycle (110 receiving 12 weeks of HyBryte treatment and 45 receiving 6 weeks of placebo treatment followed by 6 weeks of HyBryte treatment), demonstrated that the response rate among the 12-week treatment group was 40% (p<0.0001 vs the placebo treatment rate in Cycle 1). Comparison of the 12-week and 6-week treatment groups also revealed a statistically significant improvement (p<0.0001) between the two groups, indicating that continued treatment results in better outcomes. HyBryte continued to be safe and well tolerated. Additional analyses also indicated that HyBryte is equally effective in treating both plaque (response 42%, p<0.0001 relative to placebo treatment in Cycle 1) and patch (response 37%, p=0.0009 relative to placebo treatment in Cycle 1) lesions of CTCL, a particularly relevant finding given the historical difficulty in treating plaque lesions in particular.
The third (optional) treatment cycle (Cycle 3) was focused on safety and all patients could elect to receive HyBryte treatment of all their lesions. Of note, 66% of patients elected to continue with this optional compassionate use / safety cycle of the study. Of the subset of patients that received HyBryte throughout all 3 cycles of treatment, 49% of them demonstrated a positive treatment response (p<0.0001 vs patients receiving placebo in Cycle 1). Moreover, in a subset of patients evaluated in this cycle, it was demonstrated that HyBryte is not systemically available, consistent with the general safety of this topical product observed to date. At the end of Cycle 3, HyBryte continued to be well tolerated despite extended and increased use of the product to treat multiple lesions.
Overall safety of HyBryte is a critical attribute of this treatment and was monitored throughout the three treatment cycles (Cycles 1, 2 and 3) and the 6-month follow-up period. HyBryte’s mechanism of action is not associated with DNA damage, making it a safer alternative than currently available therapies, all of which are associated with significant and sometimes fatal, side effects. Predominantly these include the risk of melanoma and other malignancies, as well as the risk of significant skin damage and premature skin aging. Currently available treatments are only approved in the context of previous treatment failure with other modalities and there is no approved front-line therapy available. Within this landscape, treatment of CTCL is strongly motivated by the safety risk of each product. HyBryte potentially represents the safest available efficacious treatment for CTCL. With very limited systemic absorption, a compound that is not mutagenic and a light source that is not carcinogenic, there is no evidence to date of any potential safety issues.
The Phase 3 CTCL clinical study was partially funded by the National Cancer Institute via a Phase II SBIR grant (#1R44CA210848-01A1) awarded to Soligenix, Inc. In addition, the FDA awarded an Orphan Products Development grant to support the evaluation of HyBryte for expanded treatment in patients with early-stage CTCL, including in the home use setting. The grant, totaling $2.6 million over 4 years, was awarded to a prestigious academic institution that was a leading enroller in the Phase 3 FLASH study.
About Cutaneous T-Cell Lymphoma (CTCL)
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 where they form various lesions, typically beginning as patches and may progress to raised 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. Typically, CTCL lesions are treated and regress but usually return either in the same part of the body or in new areas.
CTCL constitutes a rare group of NHLs, occurring in about 4% of the approximate 700,000 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 25,000 individuals in the U.S., with approximately 3,000 new cases seen annually.