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Background: Monitoring proteinuria is important for the management of patients with cancer treated with anti-vascular endothelial growth factor (VEGF) or anti-VEGF receptor (VEGFR) inhibitors (VEGF/Ri). Here we investigated the difference between the urine protein/creatinine ratio (UPCR) and a qualitative value test (QV) on the decision making of treatment continuation and the usefulness of UPCR testing in patients with gastrointestinal cancer treated with anti-VEGF/Ri.Methods: From January 2017 to December 2018, a survey was conducted based on the medical records of patients with gastrointestinal cancer with a QV of ≥2+ during the use of anti-VEGF/Ri at seven Japanese institutions participating in the Onco-nephrology Consortium. The primary endpoint was the ratio of the worst UPCR < 2.0 (low UPCR) in cases with a QV2+ at the point of the first proteinuria onset. The secondary endpoints were a comparison of low UPCR and worst UPCR ≥2.0 (high UPCR), the concordance rate between UPCR and QV in the Common Terminology Criteria for Adverse Events (CTCAE) grading, and the differences in the decision making for anti-VEGF/Ri continuation.Results: Among the 71 patients enrolled, the proportion of low UPCR in onset QV2+ (n = 53) was 66% (n = 35). In a comparison between low (n = 36) and high UPCR cases (n = 24), body weight (P = 0.036), onset QV status (P = 0.0134), and worst QV status (P < 0.0001) were significantly associated with UPCR levels. The concordance rate for CTCAE Grade 2 of both the QV and UPCR was 83%. Regarding the judgment of anti-VEGF/Ri continuation, treatment was continued in 42.4% of cases when the QV became 3+, whereas only 25% continued treatment when the UPCR value became high.Conclusion: Urine dipstick test results may overestimate proteinuria, and the UPCR result tended to be more critical than the QV when deciding the treatment policy.Trial Registration: This study is a multiple institutional retrospectively registered observational trial.Clinical Trial Number: University Hospital Medical Information Network (UMIN) Clinical Trials Registry (protocol ID UMIN000042545 ). [ABSTRACT FROM AUTHOR]

Background: S-1 is an oral anticancer drug, containing tegafur (a prodrug of 5-fluorouracil, 5-FU), 5-chloro-2,4-dihydroxypyridine, and potassium oxonate. As renal dysfunction is known to increase exposure of 5-FU following S-1 administration, the incidence of severe adverse reactions is increased in patients with impaired renal function. However, no reliable information on its dose modification for patients with renal dysfunction has been provided. Methods: We conducted a prospective pharmacokinetic study to develop an S-1 dosage formula based on renal function. Sixteen cancer patients with various degrees of renal function received a single dose of S-1 at 40 mg/m. A series of blood samples were collected at predefined times within 24 h to assess the plasma concentration profiles of 5-FU, 5-chloro-2,4-dihydroxypyridine, and tegafur. A mathematical model for the relationship between renal function and exposure of 5-FU was constructed by a population pharmacokinetic analysis. Results: The clearance of 5-FU following S-1 administration was related to body surface area and creatinine clearance in the range 15.9-108.8 mL/min as estimated by the Cockcroft-Gault equation. The S-1 dosage formula was derived as follows:where AUC is the area under the concentration-time curve, CLcr is creatinine clearance, and BSA is body surface area. The recommended daily doses of S-1 in Asia and Europe were also proposed as nomograms according to exposure matching to the previously reported area under the concentration-time curve of 5-FU, which confirmed the efficacy and toxicity in pivotal registration studies. Conclusions: We have developed a novel formula for determining the S-1 dosage on the basis of renal function. Further validation is needed to confirm the formula for practical application. [ABSTRACT FROM AUTHOR]