Acne is the single most common skin disease worldwide, and affects up to 85% of all 12-24 year olds. Adults in their twenties, even into their forties, can get acne.
The lesions that characterize acne are comedones (non-inflammatory lesions), inflammatory papules and pustules. Features of more severe acne include nodules and cysts. Some patients will present with all types of lesions but most will only show a combination of a few lesion types. The pathological features include hypercornification of the follicle with follicular plugging, increased sebum production, colonization of the follicle by the bacterium Propionibacterium acnes and inflammation. Follicular and perifollicular inflammation is thought to be related to the P acnes infection. Severity of acne also seems to correlate with the intensity of sebum production.
Can lead to scarring
While not a life-threatening condition, acne can be disfiguring, impact self esteem and lead to low quality of life for patients. Severe acne can lead to serious and permanent scarring, and even moderate cases can lead to scarring. Acne is graded as mild, moderate or severe. Each year, US dermatologists register more than 5 million visits concerning acne. Of those who seek medical advice from a dermatologist, about 70% have moderate to severe acne.
High unmet medical need for patients with moderate to severe acne
The current mainstay of treatment for patients with moderate to severe acne is oral antibiotics and/or retinoids. By avoiding the risk of increased antibiotic resistance from long term exposure, and providing a highly tolerable alternative to isotretinoin, photodynamic therapy has the potential to satisfy this unmet medical need.