Evidence · 11 min read
Clascoterone Phase 3: what SCALP 1 and SCALP 2 showed
Largest topical AGA programme to date. Both trials hit their hair-count endpoint. The percentages need a translator.
Trial design
SCALP 1 (NCT05910450) and SCALP 2 (NCT05914805) were identical in structure: 6-month randomised, double-blind, vehicle-controlled Phase 3 studies in men aged 18+ with mild-to-moderate androgenetic alopecia (modified Norwood–Hamilton III vertex to V), then a further 6-month single-blind extension.
Combined enrolment: 1,465 men at 51 centres in the United States and Europe. Dosing in the active arm: clascoterone 5% solution twice daily. Co-primary thinking in the programme centred on Target Area Hair Count (TAHC) — hairs counted in a tattooed circle of scalp under magnification — plus patient-reported outcomes.
The headline numbers (6 months)
Cosmo’s December 2025 topline:
- One study: 539% (5.39×) relative improvement in TAHC versus vehicle
- The other: 168% (1.68×) relative improvement versus vehicle
- Pooled commentary from analysts clustered around ~252% relative improvement
- Treatment-emergent adverse events similar to vehicle; most events judged unrelated to drug
The CEO publicly attributed the gap between 539% and 168% to different baseline hair counts, not two different drugs. Same absolute change from a lower baseline produces a larger relative percentage. That explanation is plausible. It is also why relative percentages are a terrible way to brief patients.
Relative vs absolute
If vehicle stays flat or sheds slightly, a modest absolute gain in the active arm becomes a huge percentage. Phase 2 published-style figures sat nearer +10 to +14 hairs per cm². Until the full Phase 3 tables are in a journal, treat 539% as a statistician’s ratio, not a before-after selfie.
Independent commentators (including Perfect Hair Health’s public breakdown) have made the same point: relative change versus a near-zero denominator is how press releases travel. Absolute density and hair-width change are how you decide if a product is worth a daily ritual.
Patient-reported outcomes
Company communications said PROs reached significance in one study and trended positive in the other, with the combined analysis statistically significant and directionally aligned with TAHC. At 12 months, men who stayed on drug reported a +24.5% relative improvement in treatment satisfaction versus vehicle groups, plus good ease-of-use scores. Adherence is the hidden endpoint in hair loss. A twice-daily solution that feels easy is commercially more important than a 2% extra hair count that nobody will apply.
What we still do not have (August 2026)
- Full peer-reviewed Phase 3 efficacy paper with absolute TAHC, responder rates, and photographs scored by blinded investigators
- Head-to-head versus 5% minoxidil or 1 mg finasteride
- Robust female AGA data for the 5% solution
- Label, price, and formulary status — none of these exist until approval
The 12-month extension is the more interesting clinical story. That lives on the 12-month results page.