Soligenix has terminated the late-stage development programme for its topical cutaneous T-cell lymphoma (CTCL) therapy, HyBryte, after the drug failed to show early signs of success in a Phase III programme.
Soligenix designed the topical gel, previously dubbed SGX301 or synthetic hypericin sodium, to work alongside visible light to target and destroy malignant T-cells found in CTCL skin lesions without damaging cellular DNA. The company theorised that, by activating the hypericin with visible light in the red-yellow spectrum – which these T-cells selectively absorb – HyBryte could selectively drive the death of the disease-causing cells.
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However, this approach may not have been as effective as Soligenix would have hoped, as interim analysis by the data monitoring committee found the Phase III FLASH2 trial (NCT06470451) was unlikely to meet its primary goals back in May 2026. After an assessment, Soligenix opted to put the topical therapy’s development on ice in CTCL – sharing this news in a Q2 earnings release.
CTCL is a rare form of non-Hodgkin lymphoma that causes tumours to grow on the skin. In the early stages of disease, physicians often prescribe topical creams and light therapy as treatment, though patients with advanced stages of the disease generally receive either stem cell transplants, targeted treatments, or chemotherapy.
With HyBryte’s commercial hopes in CTCL dashed, Soligenix’s president and CEO, Christopher Schaber, noted the company will now place a focus on progressing its pipeline candidate, dusquetide, in the rare inflammatory blood vessel condition, Behçet’s disease. The drug has already demonstrated its safety and tolerability in a Phase II study (NCT06386744).
The company will also work to secure commercial opportunities for its ThermoVax platform, which facilitates the freeze-drying and ambient storage of protein and adjuvant-based vaccines to reduce global reliance on cold-chain logistics. Soligenix is currently in the early stages of developing vaccine candidates for Filoviral strains such as Zaire and Sudan Ebolavirus, as well as a Covid-19 jab.
Advancements in treating CTCL
Over the years, there have been some developments across the CTCL treatment paradigm to improve patient outcomes.
This includes the approval of drugs like Seagen-developed Adcetris (brentuximab vedotin), which is commercialised by Pfizer in the US and Canada and Takeda in all other locations globally. Since its regulatory greenlight in 2017, the drug has become the best-selling therapy in this indication, bringing in $1.8bn in 2025.
More recently, the US Food and Drug Administration (FDA) also approved Citius Oncology’s Lymphir (denileukin diftitox) back in 2024, adding a treatment option for patients in the relapsed/refractory setting. Recently, the company raised $36.5m to ramp up Lymphir’s commercialisation efforts.
Despite the advancements made in treating CTCL, patients still face significant unmet needs, with delayed diagnosis, as well as challenges treating its associated chronic itch remaining prevalent across the impacted population.
Looking forward, researchers tout the potential role of kinase inhibitors and CAR-T therapies as the new frontier in CTCL treatment.
