Otsuka Pharmaceutical Co has been boosted by the news that regulators in the USA are fast-tracking the firm's tolvaptan for a kidney disorder.

The US Food and Drug Administration has granted a priority review to tolvaptan for the treatment of autosomal dominant polycystic kidney disease (ADPKD). It is a genetic illness characterised by the development of multiple cysts in the kidneys and is the most common inherited kidney disease, accounting for about 5% of end-stage renal disease in the USA.

Tolvaptan, which is a vasopressin 2 receptor antagonist, is already approved as Samsca on both sides of the Atlantic to treat hyponatremia. For the ADPKD indication, the FDA has given Otsuka a target action date of September 1.

The filing for ADPKD, which affects in one in every 1,000-4,000 sufferers globally, is based on Phase III trials which demonstrated reductions of change in total kidney volume for subjects receiving tolvaptan compared to placebo. However in January, Otsuka and the FDA that of the 1,400 patients involved in the trial, three suffered serious liver injury that was "either probably or highly likely to be caused by tolvaptan".

Still, Otsuka president Taro Iwamoto noted that the submission of the NDA represents an important milestone for the company and if approved by the FDA, will become the first drug for ADPKD.