Corsair Pharma, Inc., is developing a transdermal prodrug of treprostinil to treat pulmonary arterial hypertension (PAH). Corsair's delivery system patch that delivers an inactive prodrug (CO-254) which crosses the skin, enters the blood, and converted rapidly and completely to treprostinil in the liver, giving consistent blood levels of treprostinil comparable to an infusion pump. A transdermal patch alleviates the need for central vein catheter placement or continuous subcutaneous infusion. Since the prodrug is inactive, the system patch also avoids the issues of infusion site pain and infusion site reactions. The transdermal prodrug will allow physicians greater flexibility in mono- and combination therapy and will provide patients a well-established, safe and effective therapeutic choice that is better tolerated with fewer side effects.
While there are several classes of drugs for PAH, as the disease progresses most patients will be treated with a prostacyclin analog either alone or in combination with another class of therapy. Because prostacyclins are short-lived in the body, best results are obtained either by continuous intravenous or subcutaneous administration. The former requires insertion of a catheter into a central vein within the chest while the latter involves the inconvenience of a needle continuously implanted in the skin and a pump which must be worn on the body. Worse, the majority of patients using subcutaneous administration experience severe pain at the injection site. To make this treatment more tolerable, various dosage forms have been developed and marketed. An oral form however produces large swings in blood levels leading to adverse events (at the peaks) and under-treatment (at the troughs). An inhaled form requires multiple daily doses and causes local nasal irritation.
PAH is a serious, progressive and ultimately fatal disease that causes shortness of breath, markedly reducing quality of life. Current treatments offer some symptomatic relief but only prostanoids such as treprostinil have been shown to prolong life.
PAH is an orphan disease that affects an estimated 100,000 people globally. In the United States, approximately 25,000 patients are currently under treatment. Multiple drug therapies target three pathways: prostacyclin, endothelin receptors, and nitric oxide. Combination therapy is increasingly used. Annual pricing for prostacyclin therapies ranges from $60,000 to $300,000. Cowen & Company Therapeutic Categories Outlook, September 2015 (p. 2049) estimates US and global markets for PAH therapies at $2B and $4B, respectively.