CB-03-01

CB-03-01, developed and marketed under the name clascoterone (brand name Winlevi), is the development code for cortexolone 17alpha-propionate, a topical androgen receptor inhibitor ^[1][2]. Structurally it is a steroidal ester closely related to cortexolone (11-deoxycortisol), engineered so that when applied to skin it competes with androgens such as dihydrotestosterone for binding to androgen receptors in the sebaceous gland and hair follicle while being rapidly metabolized to limit systemic activity ^[2][5].

Clascoterone was developed by Cassiopea, a company spun out of Cosmo Pharmaceuticals, as a treatment for androgen-dependent skin disorders including acne vulgaris and androgenetic alopecia ^[2]. In August 2020 the United States Food and Drug Administration approved clascoterone cream 1% for the topical treatment of acne vulgaris in patients twelve years of age and older, making it the first topical antiandrogen approved for acne and the first drug with a new mechanism of action for the condition in many years ^[2].

Its primary research and clinical application is acne, where altered sebum production, androgen signaling, inflammation, and bacterial proliferation all contribute to disease; a higher-concentration solution has also been studied for androgenetic alopecia ^[1][2]. Because systemic antiandrogens carry hormonal side effects and are generally avoided in male patients and during pregnancy, a locally acting topical antiandrogen fills a distinct therapeutic niche ^[4]. Clascoterone is an approved prescription drug supplied as a 1% cream ^[2][3].

Clascoterone (CB-03-01) is a topical androgen-receptor antagonist approved for acne, and the most common effects are local skin reactions such as irritation, redness, dryness and itching. Clinical study observed possible reversible suppression of the HPA (adrenal) axis with extended or large-area application, and its longer-term systemic safety when used off-label, for example on the scalp for hair loss, is less well characterized.

Clascoterone (development code CB-03-01) is the 17-alpha-propionate ester of cortexolone, developed by the Italian pharmaceutical company Cassiopea S.p.A., a spin-off of Cosmo Pharmaceuticals. It was designed to deliver androgen receptor blockade directly to the skin while being rapidly hydrolyzed to the inactive metabolite cortexolone after absorption, thereby avoiding the systemic hormonal effects of oral antiandrogens. The United States Food and Drug Administration approved clascoterone cream 1% under the brand name Winlevi in August 2020 for the treatment of acne vulgaris in patients twelve years of age and older, making it the first genuinely new mechanism of action approved for acne in roughly four decades. A higher-strength solution, under the proposed name Breezula, has been investigated separately for androgenetic alopecia.

Clascoterone is widely regarded as a landmark in acne pharmacology because it introduced the first topical androgen receptor inhibitor, addressing the hormonal driver of acne without the systemic risks that limit spironolactone or oral antiandrogens. Dermatologists have received it favorably for its strong tolerability profile, with most local skin reactions in trials reported as absent, trace, or mild, and it is now being studied in combination with retinoids such as adapalene to target multiple pathways at once.

Discussion often notes that it is one of the few acne treatments considered suitable for both male and female patients on hormonal grounds. Honest appraisal acknowledges that absolute treatment-success rates in the pivotal trials, while significantly better than vehicle, left many patients short of clear skin, and that twice-daily application over months is required. Long-term real-world data continue to accumulate.