After the FDA denied approval for Soligenix’s rare cancer treatment in February, the agency has now said a second clinical trial with positive results will be required to accept another request for approval.
The news comes after Soligenix met with the FDA to discuss a refusal-to-file letter for the biotech’s investigational treatment for cutaneous T-cell lymphoma (CTCL), a class of non-Hodgkin’s lymphoma that currently has no cure. Dubbed HyBryte, Soligenix’s treatment is a synthetic form of hypericin that has received both orphan drug and fast track designations from the FDA. The photodynamic ointment is designed to inhibit growth of malignant T cells when activated by fluorescent light.
The theory appeared to be justified in a phase 3 readout last year from 166 patients with CTCL. Patients receiving HyBryte had a lesion response rate of 49% after three cycles of treatment, compared to 4% who received placebo.
Despite the data, the FDA shot down Soligenix’s application, deciding it “was not sufficiently complete,” a determination that sent the biotech’s stock plunging.
Now the FDA has said in order to accept a new drug application for HyBryte, the biotech must conduct a second clinical study that turns out positive results.
Shares of Soligenix, which had initially anticipated approval in the second half of 2023, fell 14% to $1.42 as of 10:30 a.m. ET Friday compared to $1.64 at closing yesterday.
“While we are very disappointed by this delay, Soligenix and its clinical investigators remain committed to working with the FDA and advancing HyBryte to market for patients suffering with CTCL,” Soligenix CEO Christopher Schaber, Ph.D., said in an April 14 release.
The phase 3 trial—which was partially funded with a grant from the National Cancer Institute—was the largest double-blind, placebo-controlled clinical trial ever conducted in the CTCL population, according to the CEO.
“While we are surprised that the FDA did not accept our submitted NDA for filing and review, it was very clear that the FDA’s thinking has evolved in evaluating CTCL therapies since our initial protocol discussions on Study HPN-CTCL-01 and that another phase 3 study will be required to support an NDA for HyBryte,” Schaber concluded.
Based on the new discussions with the FDA, Soligenix plans to work with the FDA to determine protocol expectations and “evaluate the feasibility” of another trial, according to the company release.