Characterization of Tumor Responses in Patients with Unresectable Hepatocellular Carcinoma Treated with Lenvatinib in the Phase 3 Randomized Trial: REFLECT.

Introduction: In REFLECT, lenvatinib was noninferior to sorafenib in terms of overall survival (OS) in patients with unresectable hepatocellular carcinoma (uHCC; median 13.6 vs. 12.3 months; HR 0.92, 95% CI 0.79-1.06). The objective response rate (ORR) with lenvatinib was 18.8% by blinded independent imaging review (IIR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1); per modified RECIST (mRECIST), the ORR was 40.6%. We sought to further characterize these tumor responses and explore ORR's importance among outcomes for patients with HCC. Methods: Efficacy assessments included all patients randomly assigned to receive lenvatinib treatment (if bodyweight ≥60 kg, 12 mg/day; if <60 kg, 8 mg/day). Time to first objective response (TTR) and duration of response (DOR) included patients who achieved a partial or complete tumor response. Tumors were assessed by IIR per RECIST v1.1 or mRECIST. Results: Four hundred seventy-eight patients were randomly assigned to receive lenvatinib. By IIR, 90 patients (18.8%) achieved an objective response per RECIST v1.1, and 194 (40.6%) had an objective response per mRECIST. Median TTR/DOR were 2.8 months/7.4 months in responders per RECIST v1.1, and 1.9 months/7.3 months in responders per mRECIST, respectively. Per baseline disease characteristics, ORRs by Child-Pugh score (A5/A6) were 21.2%/11.2% per RECIST v1.1 and 42.9%/33.6% per mRECIST, respectively. By baseline alpha-fetoprotein level (<400/≥400 ng/mL), ORRs were 21.4%/15.4% per RECIST v1.1 and 45.6%/33.8% per mRECIST, respectively. Incidences of treatment-related treatment-emergent adverse events were 98.9% in responders per RECIST v1.1 and 97.9% in responders per mRECIST. Conclusions: Responses were seen even in those patients with more severe disease at baseline. Tumor responses occurred early and were durable.