A Dose Escalation and Safety Study of I5NP to Prevent Acute Kidney Injury (AKI) in Patients at High Risk of AKI Undergoing Major Cardiovascular Surgery (QRK.004)

Inclusion Criteria (before surgery): * Patient age between 21 years and 85 years old * Patient is capable of giving consent * Patient is willing and able to comply with the visit schedule and study procedures including post-hospitalization discharge follow-up * Patient is undergoing any major cardiac or vascular surgery requiring the use of cardiopulmonary bypass machine (CBM) * Patient has a cumulative score of ≥ 5 on the Cleveland Clinic Foundation (CCF) Acute Kidney Injury (AKI) risk factor scale OR the patient has an estimated GFR (eGFR) \<60 mL/min/1.73 m2, as determined from the simplified (4-variable) MDRD (Modification of Diet in Renal Disease) equation at the time of the Screening/Baseline examination * The patient reports that they are up to date and have had normal findings on their age- and sex-appropriate cancer screening, per American Cancer Society guidelines, for breast cancer, cervical cancer, rectal cancer, and prostate cancer. If a patient is not up to date, the relevant screening test must be performed and a normal result documented prior to dosing. Inclusion Criteria (during surgery): * Patient must have been on cardiopulmonary bypass machine (CBM) Inclusion Criteria (after surgery): * Patient must be in the ICU for dosing to facilitate study procedures including PK blood draws and PK urine sampling Exclusion Criteria (before surgery): * Patient has had cancer or may be predisposed due to a family history of: * a clinical syndrome predisposing to malignancy, such as Familial Polyposis Coli, Von Hippel Landau disease (associated with renal cell cancers and renal cysts) and Li-Fraumeni syndrome (associated with inherited mutations of the p53 tumor-suppressor gene) * the same malignancy in two or more first- or second-degree relatives * Patient has a history of any abnormality on chest X-ray that could represent a malignancy * Patient has a clinically significantly elevated pancreatic and/or hepatic enzyme level, defined as any grade 2, 3 or 4 value according to the National Cancer Institute (NCI) Common Toxicity Criteria for Adverse Events (CTCAE), version 3.0 * Women of childbearing potential are to be excluded from this study. Every female subject is considered of childbearing potential unless she has had sterilization surgery, or is post-menopausal. * Women 21-59, post-menopausal is defined as no menses for at least 12 months and an elevated follicle stimulating hormone (FSH) level. * Women 60-85, post-menopausal is defined as no menses in at least 12 months. * Patient has participated in a study of an experimental therapy in the last 30 days * Patient is currently receiving immunosuppressive therapy \[this criterion does NOT apply to topical steroids and inhalation steroids for chronic obstructive pulmonary disease (COPD) and/or asthma\] * Pre-operative extracorporeal membrane oxygenation * Patient has Intra-Arterial Balloon Pump (IABP) or other Left Ventricular Assist Device (LVAD) * Evidence that patient is experiencing possible AKI prior to surgery, defined as a \> 1.5 times increase in serum creatinine from screening to any time prior to surgery * Patient has comfort measures only or do not resuscitate (DNR) status * Patient is participating in a concurrent interventional study * Patient has received intravenous contrast material \< 24 hours prior to surgery * In the opinion of the investigator a pre-operative concomitant disease or clinical/laboratory finding that significantly raises the risk of complications in the post-operative period and therefore precludes dosing of the patient Exclusion Criteria (during surgery): * In the opinion of the investigator, an intra-operative complication has occurred that significantly raises the risk of complications in the post operative period and therefore precludes dosing of the patient Exclusion Criteria (after surgery): * In the opinion of the investigator, a complication has occurred in the post-operative period at any time prior to dosing that significantly raises the risk of further complications and therefore precludes dosing of the patient