Upcoming FDA PDUFA: Otsuka Pharmaceutical - Samsca (tolvaptan)

Date of FDA Decision (PDUFA): September 1, 2013
Company name: Otsuka Pharma
Stock ticker: TYO: 4578 OTK.F
Location: Tokyo, Japan
Type of application: Supplemental NDA; Novel Indication; Fast-Track Review
Name of drug: Samsca (tolvaptan)
Indication: Autosomal dominant polycystic kidney disease (ADPKD)

24^th July 2013:

Market Cap	$18.3 Bln
52-week range	$23.8 – 37.11
Avg. volume	889,570

Otsuka is a diversified pharmaceutical company based in Tokyo and Osaka, Japan. It is currently the second largest pharma player in Japan, and, despite its predominantly nutraceutical focus, Otsuka is actively looking to specialize in innovative pharmaceuticals targeting central nervous system disorders and oncology.

Tolvaptan is a selective, competitive vasopressin receptor 2 antagonist approved by the FDA in 2009 for the treatment of hyponatremia (low blood sodium levels) associated with congestive heart failure, cirrhosis, and the syndrome of inappropriate antidiuretic hormone (SIADH). The drug is currently awaiting an FDA decision for a novel indication, Autosomal Dominant Polycystic Kidney Disease (ADPKD), a genetic illness characterized by the development of multiple cysts in the kidneys. ADPKD is the most common inherited kidney disease, accounting for about 5% of end-stage renal disease in the USA.

In a recently published tolvaptan trial the study met its primary and secondary end points. When given at an average dose of 95 mg per day over a 3-year period, tolvaptan slowed the usual increase in kidney volume by 50% compared to placebo (2.80% per year versus 5.51% per year, respectively, p<0.001) and reduced the decline in kidney function when compared with that of placebo-treated patients by approximately 30%. 

However, in April 2013 Samsca's clinical trials also revealed an increased risk of the drug to patients with underlying liver disease, and patients who take tolvaptan for extended period of time. Because of the findings, on May 1, 2013, the FDA limited the duration and dosage of Samsca by updating its drug label. In the new label the duration of treatment was limited to 30 days, the indication of cirrhosis has been removed, and increased liver risks were added. 

If approved by the FDA, tolvaptan will become the first pharmaceutical therapy for patients with ADPKD.