Pasireotide (SOM230) is a novel multi-receptor-targeted analog that has high affinity for four of the five SST receptor subtypes (SSTr1, SSTr2, SSTr3 and SSTr5); it has a 40-fold higher affinity and 158-fold higher functional activity for the SST5 receptor than octreotide. Because of its broad receptor binding profile, pasireotide may be more potent in Polycystic Liver Disease (PLD) than octreotide. In this randomized double blind placebo controlled trial the investigators will compare SOM230 treatment to placebo for 12 months in patients with PLD. The primary endpoints will be assessed at 12 months and patients receiving placebo then crossed over to SOM230, permitting all participants to receive SOM230 for the subsequent two years. Magnetic resonance imaging (MRI) will be used to assess liver volume - the primary endpoint, which will be assessed at baseline, end of years 1 and 3. This study will assess the efficacy and safety of SOM230 in reducing total liver volume and improving quality of life over 12 months. (The investigators will not be assessing efficacy at 24 months.) The therapy way be effective in PLD but also may prove to be effective for many more patients with Polycystic Kidney Disease (PKD) which will be evaluated using eGFR and kidney volume using MRI.~The investigators plan to add other sub-sites in other locations.
The purpose of this study is to compare SOM230 treatment to placebo. The investigators will also assess the efficacy and safety of SOM230 in reducing total liver volume and improving quality of life.