The goal of this first-in-human clinical trial is to examine the safety and efficacy of treatment with a new peritoneal dialysis (PD) device called WEAKID (WEarable Artificial KIDney for peritoneal dialysis). This device, unlike conventional PD, allows for continuous flow of dialysate inside the abdominal cavity combined with continuous regeneration of spent dialysate thanks to sorbents that remove toxins from the fluid.

The study will include PD patients of 18 years or older with a well-functioning peritoneal catheter and no history of a PD-related infection for at least eight weeks prior to enrolment.

The main purpose of this study is to assess the (short-term) safety of the WEAKID system in a limited number (n=12) of patients and sessions.

Participants will undergo six treatment sessions (of four or eight hours) in total over a period of two weeks, either with or without a sorbent chamber.

Participants will be asked to collect urine and dialysate the week before the first treatment and during the treatment days. In addition, blood samples will be collected before and during the treatment weeks in order to compare the effects of conventional PD with that of WEAKID treatment. A peritoneal equilibrium test will also be done before and after the treatment weeks to test the function of the lining of the abdomen (the peritoneal membrane).

Peritoneal dialysis (PD) is a life-sustaining renal replacement therapy for patients with end-stage kidney disease (ESKD). With PD, waste solutes and excess water are drawn from the blood across the peritoneal membrane lining the abdominal cavity via diffusion and osmosis, respectively, into dialysis fluid (peritoneal dialysate) that is introduced into the abdominal cavity through a permanent tube (peritoneal catheter). The peritoneal dialysate is replaced 4-6 times/day either manually by the patient or automatically by a machine at night while the patient is asleep. PD is a gentle dialysis technique that provides continuous gradual dialysis while the patient is free to move during the day. However, PD has several disadvantages. Removal of waste solutes is inadequate and technique failure rate is high, contributing to poor quality of life and high (co)morbidity and mortality (10-15% per year). The low solute clearance (~1-7% of that of healthy kidneys (depending on the solute) and lower than that with haemodialysis (HD)) is due to rapid decrease of diffusive transport of solutes during a dwell due to the disappearance of the plasma-to-dialysate concentration gradient across the peritoneal membrane. The limited technique survival (median 3.7 years) is primarily due to the high incidence of recurrent infection of the peritoneal membrane (peritonitis) and exposure of the peritoneal membrane to very high, harmful glucose concentrations needed for osmotic fluid removal.

Both peritonitis and high glucose concentrations cause pathological changes of the peritoneal membrane and eventually ultrafiltration failure necessitating a switch to the more invasive and expensive HD treatment. To reduce the existing shortcomings of conventional PD, a novel continuous flow peritoneal dialysis system with dialysate regeneration (WEAKID) for PD was developed. WEAKID treatment is based on continuous recirculation of peritoneal dialysate via the single lumen peritoneal catheter with regeneration of spent dialysate by means of sorbent technology. The WEAKID nighttime system (weight: ~12 kg) is intended to be used for 8h per day (during the night) on a daily basis. Instead of performing 4-6 exchanges with fresh peritoneal dialysate per day, WEAKID uses one peritoneal dialysate filling which is continuously recirculated and regenerated. The continuous regeneration prevents saturation of the dialysate with toxins and thereby maintains a high plasma to dialysate concentration gradient which enhances diffusive transport of uremic toxins. In addition, the continuous recirculating flow of fluid along the peritoneal membrane is expected to increase the mass transfer area coefficient as observed in previous studies with continuous flow peritoneal dialysis, probably due to reduction of diffusion resistance, renewal of stagnant fluid layers at the tissue surface and an increase of the effective membrane area. Both the high plasma to dialysate concentration gradient and the increase in mass transfer contribute to an enhancement of the clearance. Another advantage of the WEAKID system is that the glucose peak load to peritoneum is lower than with traditional automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD) thanks to the buffering of the sorbents (sorbents adsorb glucose at the start, lowering the initial glucose peak, and release the glucose again at later stage) and the continuous recirculation.

The primary objective of this study is to assess the (short-term) safety of the WEAKID nighttime system in a limited number (n=12) of patients and sessions (6 sessions per patient).

Secondary objectives of this study are:

1. To evaluate the incidence of adverse events (AEs) and device deficiencies (DDs) other than serious adverse device effects (SADEs) and DDs that could have led to a serious adverse event (SAE)
2. To describe the characteristics of WEAKID treatment (i.e. number and duration of sessions, dialysate flow rates)
3. To evaluate the clinical condition and vital signs of the participants during WEAKID treatment
4. To evaluate the effectiveness of ultrafiltration (UF) in relation to glucose concentration during WEAKID treatment
5. To evaluate the efficacy of solute removal and base release of WEAKID treatment
6. To evaluate the evolution of plasma analytes during WEAKID treatment
7. To evaluate the evolution of dialysate effluent analytes of the WEAKID system
8. To evaluate the (technical) device performance of the WEAKID system by the number of device deficiencies, adverse device effects and changes in intraperitoneal pressure
9. To evaluate patient tolerance during WEAKID treatment
10. To evaluate the evolution of uremic symptoms during WEAKID treatment
11. To evaluate the effectiveness of using sorbents for dialysate regeneration and the effectiveness of continuous recirculating flow in relation to the efficacy of solute removal.

The WEAKID system will be tested in a clinical setting on 6 days over a period of 2 weeks. During the first week, the subjects will be treated with the nighttime system without sorbents for 4h (first day) or 8h (second and third day) during daytime. The second week, treatment will consist of the nighttime system with sorbents (also 4h (first day) or 8h (second and third day) during daytime).

This way, exposure to new components of the system is incremental and the effectiveness of the sorbents can be analyzed separately from the effect of continuous recirculating flow dialysis. A peritoneal equilibration test (PET) will be performed at baseline and follow-up. In addition, patients will collect 24h spent peritoneal dialysate and 24h urine followed by venous puncture for blood sampling 3 times prior to WEAKID treatment during standard PD.

Inclusion Criteria:

• ≥18 years of age
• Treated with PD for at least 3 months prior to enrolment
• Well-functioning peritoneal catheter and no peritoneal catheter replacement for at least a month prior to enrolment
• No PD-related infection (exit-site infection, tunnel infection or peritonitis) less than 8 weeks prior to enrolment (counting from the day that the treatment has been finished).
• Previous or current use of Extraneal® with no contra-indications
• Capable of understanding the patient information sheet and informed consent form (ICF) and give informed consent
• Willing and able to comply with all study procedures and attend all study visits

Exclusion Criteria:

• Patients who are unable to provide informed consent
• Patients who are unable to comply with study procedures
• Patients who received renal replacement therapy other than conventional PD less than 8 weeks prior to enrolment
• Patients who participated in an intervention trial less than 8 weeks prior to enrolment or are currently participating in an intervention trial. Patients in an observational study without any interventions or in post-market surveillance do not need to be excluded.
• Patients with a PD-related infection (exit-site infection, tunnel infection or peritonitis) less than 8 weeks prior to enrolment (counting from the day that the treatment has been finished)
• Patients with peritoneal catheter dysfunction or mechanical issues less than one month prior to enrolment
• Patients who have never used Extraneal® dialysis fluid or have a contra-indication for Extraneal®: a known allergy to cornstarch or icodextrin; maltose or isomaltose intolerance; glycogen storage disease
• Patients with an incompatible PD connection to the device (e.g. Fresenius PD system)
• Patients with haemoglobin concentrations < 6.2 mmol/L (< 10 g/dL) less than 8 weeks prior to enrolment
• Patients with hyperkalemia (> 6.0 mmol/L) or hyponatremia (< 130 mmol/L) in the 8 weeks prior to enrolment
• Patients with hypocalcemia (plasma total calcium concentration corrected for albumin <2.20 mmol/L or ionized calcium <1.15 mmol/L) or hypomagnesemia (plasma magnesium concentration <0.70 mmol/L) in the 8 weeks prior to enrolment
• Patients with any serious medical condition which in the opinion of the investigator, may adversely affect the safety of the participant and/or effectiveness of the study
• Female patients who are either (planning to become) pregnant within the study period or breast feeding
• Patients with a life expectancy <3 months
• Anticipated living donor kidney transplantation <3 months

Raw data will only be available to other researchers upon request and after approval of the Principal Investigator since the data is privacy-sensitive (pseudonymized) and commercially sensitive.

The following data will be shared (under restrictions if seen fit by the Principal Investigator) upon request:

• The raw data
• The study protocol describing the methods and materials
• The script to process the data
• The scripts leading to tables and figures in the publication
• A codebook with explanations on the variable names
• A 'read_me.txt' file with an overview of files included and their content and use.

The time period will be determined on a case-by-case basis. A data sharing agreement outlining the terms of use for the receiving party will be drawn up before data is transferred.

Data will be shared upon request after approval from the PI. The access criteria will be determined on a case-by-case basis.