Study in End Stage Renal Disease (ESRD) Patients on Hemodialysis Comparing the Theranova Dialyzer to Hemodiafiltration

Inclusion Criteria: * Patients aged 18 years or older. * Patients who are able to give IC after an explanation of the proposed study. * Patients who have Kt/Vurea \> 1.2 for the last 2 measurements, with the most recent Kt/Vurea measurement taken within 4 weeks before or during study screening. * Patients with a dialysis prescription (dialyzer, time, dialysis fluid flow rate (QD), blood flow rate (QB)) stable over 6 recent treatments. The dialysis treatment time should be 3.5 to 4.5 hours per session with minimum QB of at least 250 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 within 1 month prior to study. * Patients who have been stable on in-center HD for \>3 months prior to study enrollment * Patients who have an adequate arteriovenous (AV) fistula or graft, or dual-lumen tunneled catheter capable of providing a blood flow rate of at least 250 mL/min. * Patients with a minimum total convective volume (including ultrafiltration (UF)) of 16 L post-dilution for the most recent HDF treatment. * Patients who receive in-center treatment hemodialysis at a site that routinely implements high flux dialysis and HDF. Exclusion Criteria: * Patients who have acute renal failure with the chance for recovery. * Patients who are pre-scheduled for a living donor kidney transplant within the next six months, who plan a change to PD within the next six months, or who require single-needle dialysis therapy. * Pregnant and lactating women. * Patients with positive serology tests for Hepatitis B surface antigen, Hepatitis C total antibody), HIV and Syphilis. * Patients with known hemodynamic instability, anemia (Hgb \< 90 g/L), and/or patients with Hgb \>130g/L for coagulation risk. * Patients who are severely malnourished or with significant disease that interferes with liver synthetic function, e.g. with serum albumin \<35 g/L. * Patients with active or ongoing infection as per investigator's judgement. * Patients with history of solid tumors requiring anti-cancer therapy in the past or next 6 months, or life expectancy less than 1 year, or patients or with history of 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 in, or have previously participated in other interventional clinical trials during the past 4 weeks. * Patients who have had an allergic response to polyarylethersulfone (PAES) or polysulfone (PS) membrane or have 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.