Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hematological (hemo-) or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo- or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Renal failure requiring hemo-or peritoneal dialysis Patients who are on hemodialysis. Requirement for hemodialysis or peritoneal dialysis Patients receiving hemodialysis or peritoneal dialysis Patients who require hemodialysis Estimated creatinine clearance < 30 mL/min or use of renal replacement therapy (e.g., hemodialysis, continuous renal replacement therapy, peritoneal dialysis) within 7 days prior to Day 1 Receiving renal replacement therapy, hemodialysis, or peritoneal dialysis Renal failure requiring peritoneal dialysis or hemodialysis Renal failure requiring hemodialysis or peritoneal dialysis REGORAFENIB EXCLUSION CRITERIA: Renal failure requiring hemodialysis or peritoneal dialysis Patients who are on hemodialysis Patients who are on hemodialysis Severe renal insufficiency (estimated creatinine clearance <20 mL/min) or on hemodialysis at the time of randomization or likely to require dialysis during the study. Patients who are on hemodialysis. Patients who are on hemodialysis Expected requirement for hemodialysis while on study therapy Patients requiring hemodialysis Renal insufficiency requiring hemodialysis or peritoneal dialysis Patients who are on hemodialysis. Renal failure requiring hemodialysis or peritoneal dialysis Requirement for hemodialysis or peritoneal dialysis Patients on hemodialysis e. Renal failure needing hemodialysis or peritoneal dialysis Patients who are on hemodialysis. Expected requirement for hemodialysis while on study therapy Serum creatinine level > 1.5 x the upper limit of normal (ULN), chronic renal failure requiring hemodialysis or peritoneal dialysis. Subjects on hemodialysis or peritoneal dialysis Serum creatinine will not be used to exclude patients; patients on renal-replacement therapy (e.g., hemodialysis or peritoneal dialysis) will be eligible to participate Subjects who require routine/intermittent hemodialysis or continuous peritoneal dialysis (due to inability to provide appropriate dosing schedule for oseltamivir) at Baseline. CRRT modalities are allowed. Renal failure requiring hemodialysis or peritoneal dialysis. Renal failure requiring hemodialysis or peritoneal dialysis Receiving renal replacement therapy, hemodialysis, or peritoneal dialysis Patient is not currently on hemodialysis and/or peritoneal dialysis for management of chronic kidney disease or acute failure/conditions. Subjects currently receiving hemodialysis Stage 5 chronic kidney disease or need for hemodialysis Oliguric acute renal failure (urine output < 500 ml/day) unless already on hemodialysis Presence of significant renal disease or hemodialysis which would result in dramatic reductions of systemic levocarnitine levels Patients on hemodialysis Patients with serum creatinine > 3.0 mg/dL and patients on active dialysis for renal dysfunction are excluded Dialysis dependent renal failure Current use of a non-standard dialysis membrane Patients on dialysis within 7 days of enrollment. Research participant requires dialysis Has a history of, or is currently on, dialysis. Subject is currently on renal dialysis Patients with renal failure currently requiring dialysis of any kind are not eligible Currently on dialysis (if receiving contrast for MRI) Patients on dialysis Serum creatinine (Cr) > 2 mg/dL, dialysis, or prior renal transplant Research participant requires dialysis Serum creatinine > 2.0 mg/dl (unless using non iodinated contrast or on dialysis) Serum creatinine >= 2.0 mg/dl (unless using non iodinated contrast or on dialysis) Requiring renal dialysis Patients on dialysis Presence of active renal condition (infection, requirement for dialysis or any other condition that could affect subject's safety). Subjects with isolated proteinuria resulting from MM are eligible. Presence of active renal condition (infection, requirement for dialysis or any other condition that could affect subject's safety). Subjects with isolated proteinuria resulting from MM are eligible, provided they fulfill criteria. Renal insufficiency requiring dialysis Patients undergoing renal dialysis. Patients on dialysis. Have stable renal function without dialysis for at least 2 months prior to Investigational Product (IP) administration defined by: current or prior dialysis, current or prior dialysis, Renal failure (on dialysis) Lack of acute renal failure/requirement for dialysis, as evidenced by creatinine < 1.6 mg/dL Subjects with severe renal impairment requiring dialysis. History of renal failure requiring dialysis. History of renal failure requiring dialysis. Patients on dialysis Renal dysfunction: Creatinine levels >2 mg/dL or chronic dialysis. Subjects undergoing renal dialysis Subjects with severe renal impairment (GFR <50 mL/min/1.73 m²) or on dialysis. Not currently on renal dialysis or has a history of significant renal impairment Patients must not be dialysis dependent Patients on dialysis Patients on dialysis or with transplanted organs Diagnosis of kidney disease requiring dialysis Patients with renal dysfunction (GFR <60) or patients on dialysis If agreeing to MRI contrast, participant must not be on dialysis Currently on dialysis Chronic renal insufficiency requiring dialysis