The mechanism of resistance of hepatocellular carcinoma (HCC) to sorafenib is unknown and no useful predictive biomarker for sorafenib treatment has been reported. Accordingly, we established sorafenib-resistant HCC cells and investigated the underlying mechanism of resistance to sorafenib. Sorafenib-resistant cell lines were established from the HCC cell line PLC/PRF5 by cultivation under continuous exposure to increasing concentration of sorafenib. The IC50 values of the 2 resistant clones PLC/PRF5-R1 and PLC-PRF5-R2 were 9.2±0.47 μM (1.8-fold) and 25±5.1 μM (4.6-fold) respectively, which were significantly higher than that of parental PLC/PRF5 cells (5.4±0.17 μM) (p < 0.01 respectively), as determined by MTT assay. Western blot analysis of signal transduction-related proteins showed no significant differences in expression of AKT/pAKT, mTOR/pmTOR, or ERK/pERK between the 2 resistant clones versus parent cells, suggesting no activation of an alternative signal transduction pathway. Likewise, when expression of membrane transporter proteins was determined, there were no significant differences in expression levels of BSEP, MDR1, MRP2, BCRP, MRP4 and OCT1 between resistant clones and parent cells. However, the expression levels of MRP3 in the 2 resistant clones were significantly higher than that of parent cells. When MRP3 gene was knocked down by siRNA in PLC-PRF5-R2 cells, the sensitivity of the cells to sorafenib was restored. In the analysis of gene mutation, there was no mutation in the activation segment of Raf1 kinase in the resistant clones. Our data clearly demonstrate that the efflux transporter MRP3 plays an important role in resistance to sorafenib in HCC cells.

Aim The optimal choice between sorafenib (SOR) or lenvatinib (LEN) as the first‐line treatment for unresectable hepatocellular carcinoma (u‐HCC) remains debatable. Using propensity score matching, this study compares the outcomes of SOR and LEN in the molecular‐targeted agent (MTA) sequential treatment of u‐HCC patients. Methods This retrospective, multicenter, observational study recruited 137 u‐HCC patients who underwent primary treatment with LEN (n = 52) or SOR (n = 85) between June 2017 and June 2020 after regorafenib was approved as the secondary treatment for u‐HCC. Propensity score matching was used to reduce confounding, resulting in the selection of 104 patients (n = 52 for the SOR and LEN cohorts). Results The median overall survival was 21.8 months for LEN and 20.4 months for SOR. LEN exhibited significantly greater therapeutic efficacy as compared to SOR (objective response rate: 3.8% [SOR] vs. 42.3% [LEN], p < 0.01; progression‐free survival: 10 months [LEN] vs. 5.1 months [SOR], p < 0.01). No significant intergroup differences were noted in the rate of transition to secondary MTA treatments (SOR: 58.7%; LEN: 48.4%), adverse events (SOR: 86%; LEN: 95%), and maintenance of the Child–Pugh (CP) score during treatment. Compared to non‐MTA treatments, secondary MTA treatment achieved a greater improvement in survival (4.3  vs. 2.8 months, p = 0.0047). Multivariate analysis demonstrated that the CP score (p < 0.01) and alpha‐fetoprotein level (p < 0.01) were independent prognostic factors. Conclusions Both SOR and LEN treatments showed a clinically comparable therapeutic efficacy as the first‐line treatments for u‐HCC patients in an MTA sequential therapy.

The efficacy and safety of lenvatinib (LEN) as a second/third-line treatment for unresectable hepatocellular carcinoma (HCC) after sorafenib (SOR) therapy remains unknown. We evaluated the outcomes of second/third-line LEN treatment, investigated the sensitivity of a SOR-resistant HCC cell line (PLC/PRF5-R2) to LEN, and assessed their signal transduction pathways by protein array analysis. We retrospectively enrolled 57 patients with unresectable HCC. Fifty-three radiologically evaluated patients comprised 34 molecular-targeted agent (MTA)-naive (first-line), nine intolerant to SOR (second-line), and 10 resistant to regorafenib (third-line). The objective response rates (ORRs) were 61.8% in first-line, 33.3% in second-line, and 20.0% in third-line groups. The overall survival (OS) in the first-line was significantly longer than that in the third-line group (p < 0.05). Patients with better liver functional reserves (child score, ALBI grade) exhibited higher ORR and longer OS. The IC 50 of LEN against PLC/PRF5-R2 was significantly higher than that against PLC/PRF5. LEN significantly inhibited more LEN-related signal transduction pathways in PLC/PRF5 than in PLC/PRF5-R2 cells. This suggests that LEN is active and safe as a second/ third-line treatment for unresectable HCC. LEN seems more effective for patients with HCC with better hepatic reserve functions or before MTA-resistance is acquired because of the partial cross-resistance to SOR.

Introduction: Lenvatinib (LEN) is a novel potent multi-tyrosine kinase inhibitor, approved as first-line treatment for unresectable hepatocellular carcinoma (HCC). Considering its high objective response rate, LEN therapy could be expected to achieve downstaging of tumors and lead to conversion therapy with hepatectomy or ablation. However, the feasibility of conversion therapy after LEN treatment in unresectable HCC remains largely unknown. Patient concerns: Here, we reported 3 cases of unresectable HCC: case 1, a 69-year-old man diagnosed with ruptured HCC; case 2, a 72-year-old woman with nonalcoholic steatohepatitis-based HCC; and case 3, a 73-year-old man with a history of alcoholic cirrhosis-based HCC. Diagnosis: In all cases, cirrhosis was classified as Child-Pugh 5 and modified albumin-bilirubin grade 1 or 2a. HCC was diagnosed as Barcelona Clinic Liver Cancer (BCLC) stage B. Interventions: In all cases, LEN was initiated after conventional-transcatheter arterial embolization enforcement, while maintaining liver function. Outcomes: In all cases, the main tumor size decreased after 6 months of LEN treatment and no satellite nodes were detected, indicating downstaging of HCC to BCLC stage A. Subsequently, conversion hepatectomy or ablation was performed. After successful conversion therapy, the general condition of the patients was good, without tumor recurrence during the observation period (median 10 months). Lessons: This study demonstrated that LEN enables downstaging of HCC and thus represents a bridge to successful surgery or ablation therapy. In particular, LEN treatment may facilitate the possibility for conversion therapy of initially unresectable HCC, while maintaining the hepatic functional reserve.