Last updated on March 2020

Alfapump System in the Treatment of Refractory or Recurrent Ascites (POSEIDON Study)


Brief description of study

The POSEIDON study is a multi-center, prospective, single arm, crossover pivotal study enrolling up to 60 pivotal cohort patients and up to 40 additional Roll-in patients with refractory or recurrent ascites at up to 20 sites. Pivotal cohort patients will undergo a 3-month pre-implant observation phase after enrollment, followed by implantation of the alfapump and 24 months of post-implant follow up. An analysis will be conducted to support an application for device approval when a minimum of 40 treated pivotal cohort patients are through 6 months.

Detailed Study Description

The POSEIDON Study is a multicenter, single arm within subject crossover design pivotal trial conducted in patients diagnosed with refractory or recurrent ascites due to liver cirrhosis who meet inclusion/exclusion criteria. The study will enroll up to 60 pivotal cohort patients with refractory or recurrent ascites at up to 15 sites. In addition, up to 40 additional Roll-in patients will be allowed. An analysis will be conducted to support an application for device approval when a minimum of 40 treated pivotal cohort patients are through 6 months. Patients will be followed for longer-term safety and effectiveness for a total of 2-years post-implant. Patients with a functioning pump at 24 months may consent to continued participation in a long-term follow-up evaluation and with assessments every 6 months from 24 months through the time the pump ceases to function, pump explant or patient death. This long-term follow-up period will continue until the product is approved or the sponsor determines they will no longer pursue product approval.

Pivotal Cohort Patients

Pivotal cohort patients will be evaluated in a 3-month pre-implant observation period during which they will receive standard of care therapy consisting of paracentesis as required for removal of ascitic fluid. Following the initial 3-month observation period during which the number and volume of paracentesis and Quality of life (assessed by general HRQL scores (SF-36)) as well as disease-specific validated questionnaires (Ascites-Q) will be documented, patients will be reevaluated for eligibility for pump implant.

Roll-in Patients

In the study centers without previous experience in pump placement, training in the pump implant procedure will be conducted and up to 3 initial pump implantations conducted as roll-in cases. Roll-in patients will be sequentially enrolled at the site until sufficient experience has been obtained and the site is approved by the sponsor to enroll in the pivotal phase. Roll-in patients will not undergo the 3-month pre-implant observation period and will not be included in the Primary Analysis set but will be summarized separately for purposes of safety evaluation with effectiveness data provided as supplemental. In the event a primary implanter at the site is a replaced or added, up to 3 additional Roll-in implants will be allowed.

All patients (Pivotal and Roll-in) will undergo a final eligibility assessment prior to pump implant. If deemed eligible, patients will be implanted with the alfapump. In the 3 months post-implant, patients will be monitored with pump adjustments as needed to increase or decrease volume of fluid to be removed each day. After this period of stabilization, a 3-month primary endpoint observation period (month 4 through month 6) will begin. In each period, the protocol specifies when symptom driven (therapeutic) paracentesis can be performed per protocol as well as conditions under which the use of diuretics may be considered (all patients must discontinue diuretics post implant procedure).

The study is designed to demonstrate in pivotal cohort patients 1) a 50% reduction (superiority margin) in the per-patient ratio of post-implant 3-month observation period (M4 to M6 post implantation) to pre-implant 3-month observation period with respect to average monthly requirement for therapeutic paracentesis and 2) at least 50% of patients will achieve a 50% reduction in the requirement for therapeutic paracentesis in the same period.

Clinical Study Identifier: NCT03973866

Recruitment Status: Closed


Brief Description Eligibility Contact Research Team


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