Clascoterone was originally developed under the name CB-03-01 by Cassiopea SpA, an Italian pharmaceutical company listed on the Swiss stock exchange. On 16 July 2018, Cassiopea announced a six-month interim analysis from a Phase 2 dose-ranging trial, and it's this release that the "matches finasteride" claim traces back to.

That 20.8-versus-20.1 comparison is the basis for the widely repeated "clascoterone matches finasteride" claim, and it is worth being precise about what kind of comparison it is not: it is not a randomised head-to-head trial. The two numbers come from different studies, run by different companies, in different countries, on different populations, using target areas of different sizes (normalised only by simple division, not by any formal statistical method), and at different time points, six months for clascoterone against twelve months for finasteride in the original NDA data. Indirect, cross-trial comparisons like this can be a reasonable first-pass sanity check, but they carry none of the statistical protection a randomised trial gives you, and treating "the two numbers were similar" as equivalent to "the two drugs perform the same" overstates what the comparison can support.

This is also, separately, a different comparison from the in vitro potency figures that sometimes circulate alongside it, IC50 values of 1.55×10⁻⁶M for clascoterone versus 2.89×10⁻⁶M for finasteride in a cell-based androgen receptor assay. Those numbers describe receptor-binding potency in a lab assay, not clinical hair-count outcomes, and finasteride's actual mechanism doesn't involve binding the androgen receptor at all, it inhibits the enzyme that produces DHT. Comparing an androgen-receptor-antagonist's receptor affinity to a 5-alpha-reductase inhibitor's enzyme-inhibition potency is comparing two different kinds of measurement for two different mechanisms; a lower IC50 for one drug on one specific assay doesn't tell you which drug will grow more hair on a scalp.

The 2018 dose-ranging data raises a question that's easy to miss once attention moves to the 2025 Phase 3 results: in that earlier trial, 7.5% clascoterone twice daily (20.8 hairs) produced a substantially larger mean increase than both 5% twice daily (12.2 hairs) and 2.5% twice daily (13.0 hairs), roughly 70% higher than the 5% dose at the six-month interim point. Yet the SCALP 1 and SCALP 2 Phase 3 trials that produced the 539%/168% headline results tested only the 5% concentration, not 7.5%.

Cosmo has not, as far as AmpleLab can find, publicly explained why 5% was carried forward into Phase 3 rather than 7.5%. It means the Phase 3 programme did not test the dose that produced the largest mean hair-count increase in the earlier six-month interim analysis.

Unlike the indirect finasteride comparison above, a genuine randomised comparison against an active competitor does exist: a double-blind, three-arm proof-of-concept study in 95 men, presented at the American Hair Research Society's 2018 annual meeting in Orlando by Maria Hordinsky and colleagues, comparing clascoterone 5% (n=31), vehicle (n=33), and minoxidil 5% (n=31) over six months.

This is a more modest, and more honest, result than either "clascoterone beat minoxidil" or "minoxidil beat clascoterone" would suggest: in this small proof-of-concept trial, neither active treatment separated from vehicle at a conventional level of statistical significance, and the trial wasn't designed or reported in a way that lets clascoterone and minoxidil be compared directly against each other. It's a real, randomised, active-comparator trial, which puts it on firmer ground than the indirect finasteride comparison above, but its own numbers don't support a clean verdict either way, and that's worth knowing given how often "beat minoxidil" language circulates around this drug.

In September 2021, Cassiopea reported results from a separate Phase 2 proof-of-concept trial in women, 293 participants aged 18 to 55, comparing 5% and 7.5% clascoterone against 2% minoxidil and vehicle over six months.

This is a meaningfully less flattering result than the male programme's headline numbers, and it hasn't featured in any of the recent coverage of clascoterone's Phase 3 success, understandably, since the current Phase 3 trials enrolled men only. Independent write-ups of this same trial's per-protocol population (reported elsewhere as roughly 61 evaluable women, close to the approximately 70 randomised per protocol that Cassiopea itself cited) put responder rates at about 75% for 2% minoxidil, versus 66% for 7.5% clascoterone and 57% for 5% clascoterone, meaning minoxidil numerically outperformed both clascoterone doses on this measure. Cassiopea's own framing at the time was that female pattern hair loss is a more biologically complex condition to treat than male AGA, a reasonable caveat, though it doesn't change what the trial itself showed for women as a whole: an active, decades-old comparator numerically outperformed both clascoterone doses on some of the reported measures.

Cassiopea, the Italian company that ran all of the trials described above, was acquired by Cosmo Pharmaceuticals through a public exchange offer completed in December 2021, with Cassiopea's shares delisted from the Swiss exchange in early 2022. Every SCALP 1 and SCALP 2 trial record still lists Cassiopea SpA as the formal trial sponsor, a reminder that Cosmo's current clascoterone programme is built directly on top of Cassiopea's decade of earlier, smaller trials rather than starting fresh, both the encouraging dose-ranging signal and the more mixed female data included.

This article is provided for educational purposes and does not constitute medical advice. Clascoterone 5% solution (Breezula) is an investigational drug not approved by any regulator and not available for purchase through any legitimate channel. Winlevi (clascoterone 1% cream) is approved for acne only. AmpleLab products are cosmetic formulations, unrelated to clascoterone, and are not intended to diagnose, treat, cure, or prevent any condition.

AmpleLab.