The goal of this clinical trial is to identify the optimal dose of RMC-035 for protection of long-term renal function in adult patients undergoing cardiac surgery who are at high risk of kidney injury. It will also learn about the safety of RMC-035. The main question it aims to answer is:

• Does RMC-035 protect the function of kidneys after surgery?
• Is RMC-035 safe?

Researchers will compare RMC-035 in high dose, RMC-035 in low dose and placebo to see if

• Kidney function better for participants treated with any of the RMC-035 doses?
• What medical problems do participants have when receiving RMC-035?

Participants will

• Receive 3 doses of RMC-035 or placebo: at the beginning of surgery, end of surgery and 24h after surgery
• Have extra checkups and tests during their hospital stay
• Visit the clinic at two extra occasions at 60 days and 90 days after surgery for checkups and tests

Inclusion Criteria:

• eGFR ≥30 ml/min/1.73m2
• Scheduled for non-emergent surgery of any of the following types, with use of cardiopulmonary bypass (CPB): coronary artery bypass grafting (CABG), valve surgery, ascending aorta aneurysm surgery
• Risk factors for acute kidney injury are present
• Participant capable of providing written informed consent
• Participant agrees to study restrictions such as not to take part in another interventional study, use contraception and not donate ova or sperm

Exclusion Criteria:

• Any medical condition that makes the participant unsuitable
• Scheduled for emergent surgeries
• Scheduled for CABG and/or valve surgery and/or ascending aorta aneurysm surgery combined with additional non-emergent cardiac surgeries
• Scheduled to undergo transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR), or off-pump surgeries or left ventricular assist device (LVAD) implantation
• Experiences a cardiogenic shock or hemodynamic instability which require inotropes or vasopressors or other mechanical devices such as intraaortic balloon pumping (IABP) within 24 hours prior to surgery
• Requires any of the following within one week prior to surgery: defibrillator or permanent pacemaker, mechanical ventilation, IABP, LVAD, other forms of mechanical circulatory support.
• Diagnosed with AKI prior to surgery
• Requires cardiopulmonary resuscitation prior to surgery
• Ongoing sepsis or an untreated diagnosed clinically significant infection
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥3.0 times the upper limit of normal (ULN).
• Total bilirubin ≥2.0 time ULN
• History of solid organ transplantation
• History of renal replacement therapy
• Severe allergic asthma
• Chronic immunosuppressive treatment that may have an impact on kidney function
• Ongoing chemotherapy or radiation therapy for malignancy that may have an impact on kidney function
• Current enrolment or past recent participation in any other clinical study involving an investigational study treatment
• Previously treatment of RMC-035
• Sensitivity to any of the study interventions, or components thereof