Roll-over Study to Assess Safety of Lixivaptan in Participants With ADPKD Who Completed Study PA-ADPKD-303

This is a Phase 3, open-label, roll-over study to demonstrate the continued hepatic and non-hepatic safety and renal efficacy of lixivaptan in participants with ADPKD who previously experienced abnormal liver chemistry test results while treated with tolvaptan, were permanently discontinued from the drug for that reason, and subsequently completed study PA-ADPKD-303, the open-label lead-in study with lixivaptan.

This is a Phase 3, open-label, roll-over study to demonstrate the continued hepatic and non-hepatic safety and renal efficacy of lixivaptan in participants with ADPKD who previously experienced abnormal liver chemistry test results while treated with tolvaptan that resulted in permanent discontinuation of tolvaptan for that reason, and subsequently completed study PA-ADPKD-303, the open-label lead-in study with lixivaptan.

Assessments completed during the final 4 visits of PA-ADPKD-303, the lead-in study, will serve as the screening and baseline assessments for this roll-over study. Evaluation of eligibility will be completed at Visit 1 of this study, following signing of informed consent. Participants satisfying all study entry criteria at Visit 1 will be considered enrolled following completion of all Visit 1 study procedures and will be dispensed lixivaptan treatment to start the Lixivaptan Re-titration Period (1 to 2 weeks). During the Lixivaptan Re-titration Period, participants will have their dose of lixivaptan re-established based on the dose they were receiving at the completion of the lead-in study. Participants will continue on lixivaptan treatment for up to 104 weeks during the Maintenance Treatment Period and will be assessed at a study visit every 12 weeks. In between the quarterly study visits, participants will be required to have blood drawn for liver chemistry determinations every 4 weeks. At the end of 104 weeks, lixivaptan treatment will be stopped, and participants will enter a 4-week Follow-up Period during which final assessments of safety and efficacy will be obtained over 3 visits during a 28-day period.

Eligibility Criteria:
Inclusion Criteria:

* Male or female participants with ADPKD who completed study PA-ADPKD-303
* Continued control of hypertension without the use of a diuretic
* Continued adherence to prohibitions on concomitant medications stated in the study PA-ADPKD-303 protocol
* Willing to practice acceptable methods of birth control (both males who have partners of child-bearing potential and females of childbearing potential).
* Able to provide informed consent.

Exclusion Criteria:

* Any contraindication to continued treatment with lixivaptan
* Clinically significant incontinence, overactive bladder, or urinary retention (e.g., benign prostatic hyperplasia)
* New York Heart Association Functional Class 3 or 4 heart failure or other significant cardiac or electrocardiogram (ECG) findings that could pose a safety risk to the participant
* Hypovolemia on physical examination at Screening
* The following laboratory results based on serum drawn at Visit 24 of PA-ADPKD-303:

  * Serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) values \>1.5 × ULN
  * Total bilirubin values \>1.5 × ULN
* eGFR \<20 mL/min/1.73 m\^2 based on laboratory results from Visit 26 of PA-ADPKD-303
* A finding at Screening that precludes safe participation in the study or participants who are likely to be non-compliant with study procedures in the opinion of the Investigator or medical monitor