Otsuka Pharmaceutical begins tolvaptan Phase 3b study in patients with ADPKD

Otsuka Pharmaceutical Development & Commercialization, Inc., announced today that patient enrollment has begun for a new Phase 3b study of tolvaptan for adult patients with autosomal dominant polycystic kidney disease (ADPKD), the most common, life-threatening, inherited genetic kidney disorder. The company reached an agreement with the United States Food & Drug Administration (FDA) on a Special Protocol Assessment (SPA) for the design and planned analysis of this multi-center, placebo-controlled, double-blind, parallel-group trial designed to compare the efficacy and safety of tolvaptan (45 to 120 mg per day split-dose) in subjects with chronic kidney disease between late stage 2 and early stage 4 due to ADPKD.

"Otsuka is pleased that the FDA has agreed to the design for this study and we are happy to report that the first patient has been enrolled into the trial," said William H. Carson, M.D., president and CEO of Otsuka Pharmaceutical Development & Commercialization, Inc. "This study represents our ongoing commitment to patients with this rare genetic condition to provide them and their physicians with a novel treatment option."

The trial, which will take place at approximately 220 sites worldwide, is seeking to enroll approximately 1,300 tolvaptan-naïve adult (male and female) patients with ADPKD between the ages of 18-66, depending on their estimated glomerular filtration rate (eGFR), a renal function test, at time of enrollment.

Total study duration is about 15 months, and the treatment period will last for approximately 13 ½ months. The primary endpoint will compare the efficacy of tolvaptan treatment in reducing the change in eGFR, a renal function test, from baseline to post-treatment follow-up as compared to placebo in patients with ADPKD who tolerate tolvaptan during an initial run-in period.

The trial will also compare overall safety and specifically hepatic safety and compare incidence of ADPKD complications during the trial.

The FDA issued a Complete Response Letter for tolvaptan to treat ADPKD in August 2013 and requested further information to evaluate the efficacy and safety of the drug.