Oral FASN Inhibitor Denifanstat Shows Sebum Reduction, IGA Success in Phase 3 Acne Trial

Denifanstat, an investigational oral fatty acid synthase (FASN) inhibitor, met primary endpoints in a phase 3 randomized controlled trial in patients with moderate to severe acne, according to Julie Harper, MD, who discussed the data in an interview with Dermatology Times. The agent works by reducing sebum production via a non-hormonal mechanism, making it potentially applicable in patients of any gender. Addressing sebum production a has been difficult to address with existing therapies.

Phase 3 Trial: Design and Primary Endpoints

Harper, a board-certified dermatologist practicing in Birmingham, Alabama, and former president of the American Acne and Rosacea Society, described the phase 3 double-blind, randomized, placebo-controlled data; the trial was conducted in China enrolling 480 patients with moderate to severe acne. Patients were randomized 1:1 to denifanstat 50 mg orally or placebo for 12 weeks.

The trial met all primary endpoints. IGA success, which was defined as a score of 0 (clear) or 1 (almost clear) with at least a 2-grade improvement from baseline, was achieved by approximately 34% of patients receiving denifanstat, compared with roughly 17% in the placebo arm. The drug also produced statistically significant reductions in both inflammatory and non-inflammatory lesion counts.

A 40-week open-label extension enrolled 240 patients, providing safety data out to 52 weeks for a portion of the cohort. Adverse events occurring at a rate greater than 5% were limited to dry skin and dry eye. No serious adverse events were reported across either study period.

Exploring Mechanism of Action

Acne pathophysiology is typically framed around 4 contributing factors: hyperkeratinization, inflammation, sebum overproduction, and Cutibacterium acnes, Harper explained. Of these, sebum has historically been the most difficult to target pharmacologically. The oral agents currently used for this purpose (combined oral contraceptives and spironolactone) are limited to female patients. Spironolactone is not FDA approved for acne. Oral isotretinoin reduces sebum and can be used in any gender, but its teratogenicity requires enrollment in the iPLEDGE program, and tolerability concerns mean it is not appropriate for all patients.

Denifanstat inhibits FASN, a key enzyme in lipid synthesis, thereby reducing sebaceous gland output through a metabolic rather than hormonal pathway, Harper told Dermatology Times. Harper, added that the drug does not carry the teratogenic risk associated with isotretinoin, and that its gender-neutral applicability distinguishes it from the hormonal options currently available.

Clinical Considerations

Harper told Dermatology Times that the clinical relevance of denifanstat lies in part in the gaps it could address in current treatment algorithms. Patients who present with moderate to severe acne and have already tried multiple topical and oral regimens, or who have contraindications or objections to existing systemic options, represent a population with limited alternatives. A patient who is unwilling or unable to enroll in iPLEDGE, for example, currently has few oral options that address sebum production directly.

“Just giving people an opportunity to have their acne cleared up with a novel mechanism of action is so important,” Harper said.

She also noted that combination therapy—targeting multiple pathways simultaneously—remains a common approach for patients who do not achieve full clearance on monotherapy. A FASN inhibitor with a distinct mechanism could complement agents targeting other components of acne pathogenesis.

“It doesn’t take just one drug,” Harper told Dermatology Times. “It takes finding the right recipe, using medications in combination oftentimes, targeting these different mechanisms of action so that we improve not just what we see on the skin, but the patient’s quality of life as well.”

Development Status

Denifanstat has not received FDA approval, she said, and the phase 3 data described were generated in trials conducted outside the United States. Harper noted that FASN inhibition has not previously been employed in dermatology, representing a mechanistic class that has not been available to clinicians treating acne or other skin conditions.

“As far as I can tell, we have not fully defeated acne yet,” Harper told Dermatology Times. “My clinic is still full of acne patients who are still wanting treatment for their acne. So I’m just really grateful for this new and novel, exciting potential agent for us that’s on the horizon.”