Otsuka Pharmaceutical has become the first company in the world to obtain regulatory approval for a pharmacological treatment of autosomal dominant polycystic kidney disease (ADPKD). Samsca (tolvaptan) has been approved in Japan in 7.5 and 15mg tablet forms for extended use for the additional indication of ADPKD. Also, the new dosage form of 30mg Samsca tablets has received approval for the indication of ADPKD.
Samsca was developed over the past 26 years by the efforts of many researchers in Otsuka's Tokushima, Japan research facility. It is currently used in 14 countries and territories around the world as an aquaretic drug, which facilitates excretion of only free water without electrolyte loss due to its antagonist action on vasopressin V2 receptors. Upon a discovery that proliferation and enlargement of renal cysts are hindered by suppression of cAMP formation at vasopressin V2 receptors, Otsuka launched a new effort from 2004 to develop a drug for the rare disease ADPKD, in conjunction with world specialists. In global clinical trials (the TEMPO 3:4 trial) conducted in 15 countries on more than 1,400 patients with ADPKD, Samsca was shown to significantly suppress the rate of increase in total kidney volume by approximately 50% more than placebo. The results of these trials were published in November 2012 in the NEJM.
In Europe, as of December 2013, an application for regulatory approval of tolvaptan in ADPKD had been received and is under review. In the US, based on a review issued by the FDA, Otsuka has continued discussions with the FDA regarding supplementary data and the path forward for resubmission.