Pelage Pharmaceuticals has announced positive results from its Phase 2a clinical trial of PP405, a topical therapy for androgenetic alopecia that targets hair follicle stem cells to potentially regenerate hair growth. The randomized, double-blind, vehicle-controlled trial enrolled 78 patients and demonstrated both safety and early efficacy signals, positioning the company to advance into Phase 3 studies planned for 2026.
Novel Mechanism Targets Primary Hair Growth Pathway
PP405 represents a departure from existing hair loss treatments, which primarily focus on secondary causes such as hormones. Instead, the therapy acts on the primary biological pathway that controls the natural hair growth cycle by targeting hair follicle stem cells that remain present even in balding areas.
"Despite affecting millions, hair loss has seen remarkably little progress in clinical research," said Arash Mostaghimi, MD, MPH, FAAD, vice chair of Clinical Trials and Innovation at Brigham and Women's Hospital. "What's compelling about PP405 is that it brings scientific rigor to a space that's needed it for decades. A well-tolerated, topically delivered therapy that shows measurable biological activity this early is rare."
Significant Hair Density Improvements Observed
The Phase 2a trial evaluated patients aged 18 to 55 years who applied either 0.05% PP405 topical gel or placebo once daily for 4 weeks, with follow-up extending to 12 weeks. Results showed that 31% of men with a higher degree of hair loss who received PP405 had a greater than 20% increase in hair density at 8 weeks, compared to 0% in the placebo group.
Particularly notable was PP405's ability to induce new hair growth from follicles where no hair was previously present, suggesting genuine regenerative potential rather than simply supporting existing hair growth. This rapid response occurred just four weeks after treatment completion, contrasting with typical hair regrowth timelines of 6-12 months for current therapies.
Strong Safety Profile Supports Development
The study met its primary safety endpoint regarding treatment-related adverse events and serious treatment-related adverse events. Additionally, PP405 demonstrated no systemic absorption in blood plasma, indicating a robust safety profile for topical application.
"These early clinical results reinforce the potential of our approach to go beyond slowing the hair loss process and directly drive hair follicle regeneration," said Christina Weng, MD, chief medical officer of Pelage. "We see this as a milestone that expands the possibilities of regenerative medicine."
Addressing Significant Market Need
Hair loss affects more than 80% of men and 40% of women over their lifetimes, yet treatment options remain limited. The global market for hair loss prevention products reached $23.6 billion in 2021 and is projected to grow to $31.5 billion by 2028. PP405's mechanism targeting hair follicle stem cells positions it as a potential option for patients traditionally underserved by current treatments, including women and individuals with longstanding hair loss.
The trial enrolled a diverse population representing various skin phototypes and hair textures, with exclusion criteria including additional alopecia diagnoses, concurrent hair loss treatments, or certain medications and medical conditions. Following the randomized portion, patients were eligible for a 3-month open-label extension study to assess long-term safety.
