Reduction in Tumor Stain at 2 Weeks after Treatment Initiation Is a Predictor of the Efficacy of Lenvatinib in Patients with Unresectable Hepatocellular Carcinoma

Background and Aims: Lenvatinib is an oral anticancer drug for patients with unresectable advanced hepatocellular carcinoma (HCC). We evaluated whether a reduction in tumor stain at 2 weeks after lenvatinib treatment in patients with unresectable HCC is a predictor of early treatment efficacy at 12 weeks. Patients and Methods: Of the 23 patients who initiated lenvatinib treatment between April 2018 and January 2019, treatment efficacy was measured in 15 patients for more than 12 weeks after treatment. Changes in tumor stain, tumor size on contrast-enhanced computed tomography (CT), and serum levels of tumor markers were evaluated 2 weeks after lenvatinib treatment. Therapeutic efficacy was assessed by tumor stain and tumor size by contrast-enhanced CT within the first 12 weeks, according to the modified Response Evaluation Criteria in Solid Tumors (mRECIST) guidelines. Results: At 12 weeks, efficacy evaluation of 15 patients revealed that 11 of them experienced partial responses, for a response rate of 73.3%. In the first 2 weeks, 13 patients (86.7%) experienced a decreased tumor stain, including 10 responders (90.9%) and 3 non-responders (75.0%). All patients in the non-responder group had required a lenvatinib dose reduction due to adverse events within 12 weeks. On contrast-enhanced CT, the change rate of tumor stain to HCC at 2 weeks after treatment was <0.8 among 10 responders (90.9%) and 1 non-responder (25.0%; p = 0.033). No significant differences between responders and non-responders were observed with regard to most characteristics at baseline and at 2 weeks after treatment initiation. However, significant differences were observed between groups in the presence or absence of a dose suspension period, the presence or absence of lenvatinib dose reduction from the maximum value during the first 2 weeks, and decreased tumor stain at 2 weeks after treatment initiation. Conclusion: Reduction in tumor stain at 2 weeks after lenvatinib treatment may be an early biomarker of efficacy at 12 weeks in patients with unresectable HCC.