Study in End Stage Renal Disease (ESRD) Patients on Hemodialysis to Determine Non-inferiority of the Theranova Dialyzer Compared to the FX80 Dialyzer

Inclusion Criteria: * Patients aged 18 years or older. * Patients able to give informed consent (IC) after an explanation of the proposed study. * Patients who have Kt/Vurea \> 1.2 for the last 2 measurements, where the most recent Kt/Vurea measurement is taken within 4 weeks before or during study screening. * Patients with dialysis prescription (dialyzer, time, blood flow rate \[QB\], dialysis fluid flow rate \[QD\]) stable over 6 most recent treatments. The dialysis treatment duration time should be 3.5 - 4.5 hours per session, with QB of 220 - 300 mL/min and QD of 500 mL/min. * Patients who are on stable anticoagulation prescription and dose. * Patients with ESRD receiving chronic HD treatment with a history of thrice weekly HD, and at least 1 HDF session or HFHD, within 1 month prior to study. * Patients must be stable on in-center HD and/or HDF for \>3 months prior to study enrollment. * Patients who have an adequate arteriovenous fistula (AVF) or graft, capable of providing a blood flow rate of at least 220 mL/min. Exclusion Criteria: * Patients who have acute renal failure with the chance for recovery. * Patients who are pre-scheduled for a living kidney transplant within the next two months, who plan a change to PD within the next two months or who require single needle dialysis therapy. * Pregnant and lactating women. * Patients with positive serology tests for Hepatitis B surface antigen, positive Hepatitis C total antibody, HIV and syphilis. * Patients with known hemodynamic instability, anemia (Hgb \< 90 g/L), and/or severe bleeding risks secondary to coagulation disorders. * Patients with active or ongoing infection per investigator's judgement. * Patients with a history of solid tumors requiring anti-cancer therapy in the past or next 6 months or a life expectancy less than 1 year or patients with a history of a hematology neoplasm. * Patients diagnosed with a NYHA Class IV congestive heart failure, or acute coronary syndrome and/or who have suffered a myocardial infarction within three months prior to the start of the study. * Patients with a history of severe mental disorders. * Patients who are currently participating or have previously participated in another interventional clinical trial in the past 4 weeks. * Patients who have had an allergic response to polyarylethersulfone (PAES) or polsulfone membranes or have a history of poor tolerance to dialyzers with synthetic membranes. * Patients with advanced liver, heart or pulmonary disease as judged by the Investigator. * Patients with any comorbidity possibly conflicting with the study purpose or procedures as judged by the Investigator.