PKD Connection Blog


Lixivaptan granted orphan drug status for ADPKD

An investigational drug being developed for the treatment of autosomal dominant polycystic kidney disease (ADPKD) has received orphan drug designation by the U.S. Food and Drug Administration (FDA). Lixivaptan is a potent, selective vasopressin V2 receptor antagonist which may delay the progression of ADPKD.

Lixivaptan was previously administered to 1,673 patients across 36 clinical studies as part of a prior clinical development program for the treatment of hyponatremia. Palladio Biosciences, Inc., who owns the drug, expects to leverage the data generated in the hyponatremia clinical trial to repurpose lixivaptan and advance its development for the treatment of ADPKD.

“ADPKD is a serious progressive, inherited disease that typically affects multiple generations of entire families. Lixivaptan has the potential to slow the progression of ADPKD and possibly delay the need for dialysis or a kidney transplant,” said Lorenzo Pellegrini, Ph.D., Founder and Chief Executive Officer of Palladio. “The granting of orphan drug designation is an important milestone in the lixivaptan development program.”

Orphan drug designation was created by the FDA in 1983 to incentivize pharmaceutical companies to develop treatments for rare diseases.

According to the FDA, the Orphan Drug Designation program provides orphan status to drugs intended for treatment of a disease or disorder diagnosed in fewer than 200,000 people. Although 600,000 people are estimated to have ADPKD in the U.S., it is a highly under diagnosed disease. The orphan figure is based on actual diagnosed cases of the disease.

Pharmaceutical companies who have been granted orphan designation for investigational drugs can receive various benefits including accelerated registration and certain tax credit and marketing incentives. So if lixivaptan were to be approved for its use on ADPKD, Palladio would have reduced fees and tax breaks, decreasing the price of bringing the drug to the market.

Additionally, this recognition of ADPKD as an orphan (rare) disease could potentially mean more options for PKD patients as it may encourage more pharmaceutical companies to develop drugs to treat ADPKD. An orphan disease status may also result in the potential of faster and less expensive drug development. All treatments, however, will still be required to meet FDA standards.

Read Palladio Biosciences, Inc.’s press release.


  1. Mark says:

    This sounds super positive – a drug similair to Tolvaptan but without the potential impact to the liver.

    Is there any insight on research timelines? What phase would they start at given the existing data, and how long could we expect to wait to potentially see the drug on the market?

    1. Megan Lubis says:

      Hi Mark,
      We do not yet know and drug companies are tight-lipped because of FDA approval regulations. Sign up for alerts so you can stay-up-to-date:

  2. Ericka McCarthy says:

    Is there a set date in which this medication will start to be administered in clinics?

    1. Megan Lubis says:

      Hi Ericka,
      We do not yet know availability, but please sign-up for email alerts (and Clinical Trial Alerts) so you will be first to know!

  3. Megan Lubis says:


    There have been questions about Tolvaptan vs. Lixivaptan. Read more from our Chief Scientific Officer, David Baron: In response to the news about lixivaptan’s orphan drug designation, there have been questions from the PKD community about the difference between the investigational drug and another potential ADPKD treatment, tolvaptan.

    Tolvaptan and lixivaptan are vasopressin V2 receptor antagonists, meaning that they block the vasopressin receptor on kidney tubules, and more importantly on cells lining the cysts in PKD.

    In normal kidneys, vasopressin acts to concentrate the urine and preserve body water. The effect of these drugs in cysts is to inhibit proliferation of cells lining the cysts and secretion of fluid into the cysts that occur in response to vasopressin. This means that the cysts will grow more slowly when vasopressin is blocked.

    Tolvaptan and lixivaptan are similar in structure, but they are not identical. These differences in structure may mean that the drugs may differ in how well they work and how safe they are. These differences will be determined by comparing the results of clinical trials. It is even possible these two drugs could be compared head to head, but that is up to the drug companies.

    The FDA will work closely with the developer of lixivaptan because of its orphan drug designation. We are encouraged by this and the fact that more drug companies are interested in developing new therapeutics for PKD.

  4. James Swartz says:

    Would this drug be of any use for someone already ON dialysis?
    Thank you

  5. Louis Ray Haman says:

    My husband has pkd and is very excited about this new medicine. Could you keep us informed about when this drug will be available to him. Thanks!!!

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