Benefits of measuring urinary protein/creatinine ratio in lenvatinib treatment for unresectable hepatocellular carcinoma

529 Background: Proteinuria is a well-known lenvatinib (LEN)-associated adverse event. The standard management of proteinuria includes measurement of the urinary protein/creatinine ratio (UPCR) in patients with a qualitative result for proteinuria of ≥1+. Although several studies have shown a good correlation of the UPCR with the qualitative result, it remains unclear how the management of proteinuria by measuring the UPCR might affect the clinical outcomes. This study was aimed at revealing the effect of measuring UPCR on the treatment efficacy and safety in unresectable hepatocellular carcinoma (uHCC) patients receiving LEN. Methods: We retrospectively analyzed the data of uHCC patients who received LEN between March 2018 and February 2022 at National Cancer Center Hospital East. Patients in the UPCR group were monitored by measurement of the UPCR when the qualitative result was ≥2+, while those in the non-UPCR group were not. LEN was withdrawn when the UPCR was ≥3.5 in the UPCR group, and the qualitative result for proteinuria was ≥3+ in the non-UPCR group. Results: A total of 89 patients were included in this study, of which 39 had a qualitative result for proteinuria of ≥2+. Of these 39 patients with proteinuria, 22 were classified into the UPCR group and the remaining into the non-UPCR group. Of the 209 qualitative results of ≥2+ in the UPCR group, 10 (4.8%) corresponded to a UPCR of ≥3.5. The relative dose intensity of LEN during the first 8 weeks was significantly higher in the UPCR group (64.4%) than in the non-UPCR group (52.8 %, p = 0.047). The time to treatment failure was 12.6 months (95% CI, 6.3-16.9) in the UPCR group and 5.5 months (95% CI, 2.1-11.0) in the non-UPCR group (p = 0.125). The rate of change in eGFR from the baseline to the end of treatment was not significantly different between two groups. Conclusions: Measurement of UPCR might contribute to avoiding unnecessary interruption of LEN, because the UPCR values in most patients were below 3.5.