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Promising Results in Phase 2 Trial of ProSilic


The trial reported complete hair regrowth for a number of participants, with 76% of a partial cohort meeting the primary endpoint of 30% improvement.

Patient with Alopecia | Image Credit: © Alex Papp - stock.adobe.com

Image Credit: © Alex Papp

SiSaf Ltd, a biopharmaceutical company based in the UK that has developed several bio-courier drug delivery technologies, announced positive topline results from a licensee of the ProSilic variant in a phase 2 clinical trial evaluating its topical treatment for mild to moderate alopecia areata (AA).1

SiSaf wrote in a press release that the active pharmaceutical ingredient (API) in the licensee’s drug is a small molecule with a “well-established safety profile in dermatology,” which works through modulating the inflammatory response and the proliferation of T-cells by disrupting of the signaling pathways. They noted that until now, the instability of the molecule and its adverse events have limited its efficacy and therapeutic application. These limitations have been overcome partially through formulation with bio-courier technology, transforming the molecule into a “highly effective drug.”

“We formulated the molecule with ProSilic, one of the variants of our bio-courier delivery platform,” Suzanne Saffie-Siebert, PhD, founder and chief executive officer of SiSaf, said in the release.“This has stabilized the drug and has enabled controlled drug release, which reduces the molecule’s oxidative reactivity and boosts its anti-inflammatory potential. ProSilic also improves permeation into the skin epidermis and the hair follicle bulb target.”

SiSaf wrote that the phase 2 study results saw 158 participants with mild or moderate AA receive 1 of 4 doses, ranging from 0.25% to 2%, or placebo applied over 24 weeks. They reported that roughly 76% of the 1% dose cohort met the primary endpoint of over 30% improvement in alopecia severity. They also noted that 18% of the 1% cohort and 27% of the 2% cohort saw total hair regrowth, compared to just 3% in the placebo group.

“Among the range of bio-courier technologies, ProSilic is particularly well suited for dermal applications, such as seen here in treating spot baldness,” Saffie-Siebert said in the release. “By addressing the key drawbacks of the API, ProSilic creates a highly effective treatment option for alopecia areata – as indicated by the phase II data.“

SiSaf reported the bio-courier/ProSilic formulated product as being well tolerated, with no major adverse events. They wrote that over half of AA patients suffer from the mild to moderate form of the disease, which is associated with a significant burden, including depression and anxiety.2 SiSaf found the impact on quality of life for mild to moderate patients is equivalent to those with severe AA, and yet no approved therapies exist for these patients.

Based on the phase 2 data, SiSaf announced that the licensee is moving to late-stage clinical development and, if successful, it could lead to the drug becoming the first approved therapy and standard care for mild to moderate AA. This represents over half of the estimated 800,000 patients with AA in the US.

“We have a wealth of preclinical data demonstrating the safety and efficacy of our Bio-Courier delivery platform for a wide range of APIs and targets. We are pleased that one of our formulations has now demonstrated positive results in a phase II clinical trial,” Saffie-Siebert added in the release. “These positive and highly encouraging data demonstrate the significant input of SiSaf’s delivery technology for dermal indications and open up wider partnering opportunities for Bio-Courier formulated products for other topical applications, in both dermatology and ophthalmology. SiSaf has already generated promising data in relation to the treatment of psoriasis or hypertrophic and keloid scars.”

In addition to the SiSaf SIS-302-AA partnered program for autoimmune alopecia, SiSaf has 2 partnered programs in ophthalmology, SIS-201-CD and SIS-202-CDC for the treatment of corneal dystrophy.


  1. SISAF’s Bio-Courier technology enables clinical trial success for topical treatment of mild to moderate alopecia areata. SiSaf Ltd. June 10, 2024. Accessed June 10, 2024. https://sisaf.com/phase-two-success-alopecia/
  2. Sinclair R, Eisman S, Lee CMY, et al. Health-related quality of life of adult and adolescent patients living with alopecia areata in Australia. Australas J Dermatol. 2024; 00: 1–11. doi.org/10.1111/ajd.14311
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