FDA Slaps Refusal to File Letter on Soligenix’s Photodynamic Cancer Therapy Application

After Soligenix submitted a New Drug Application (NDA) for its proprietary photodynamic therapy to treat cutaneous T-cell lymphoma (CTCL), HyBryte, the FDA responded with a Refusal to File (RTF) letter. The New Jersey-based company said it plans to request a Type A meeting with the FDA to seek guidance from the regulatory agency to correct any issues or insufficiencies for a new application. 

HyBryte’s Promising Track Record

Soligenix designed HyBryte to treat CTCL using safe, visible light to activate synthetic hypericin, a photosensitizer topically applied to skin lesions. The company says the red-yellow spectrum that HyBryte uses penetrates the skin deep enough to treat deeper skin disease, thicker plaque, and lesions. 

Since starting development on HyBryte, the FDA granted Fast Track Designation and Orphan Drug Designation for the therapy. Soligenix recently published results from the Phase 3 FLASH trial demonstrating positive results in CTCL patients.

The FLASH trial consisted of three treatment cycles for 169 participants. After the first cycle, 16% of 116 patients receiving HyBryte achieved at least a 50% reduction in lesions. Responses from the second cycle increased to 40%, and the third cycle elicited positive responses from 49% of participants. 

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Opening the FDA’s RTF Letter

Still, even with the impressive results, the FDA did not accept the company’s December NDA for the drug. The FDA does not make RTF letters public, but Soligenix issued a press release addressing the matter, stating the FDA did not find the application sufficiently complete upon preliminary review. 

In response, the company said it intends to work with FDA staff to identify and remediate issues with the current application to submit a new NDA for HyBryte. 

President and CEO of Soligenix, Christopher J. Schaber, PhD., said, “We are fully determined to work with the FDA staff as quickly as possible to better understand the open issues and clarify the potential path to successfully resubmitting our application.”

In time, Soligenix hopes to have a clear path forward to bring HyBryte to the market, providing a novel and exciting new treatment method for CTCL. The company will have to wait a bit longer than it intended to fix any issues with its initial NDA filing. 

Author

Reed Slater