EGFR/ERBB2 Amplifications and Alterations Associated With Resistance to Lenvatinib in Hepatocellular Carcinoma

New insights into the mechanism of resistance to lenvatinib and strategies for lenvatinib sensitization in hepatocellular carcinoma

Lenvatinib is a multikinase inhibitor that suppresses vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor α (PDGFRα), as well as the proto-oncogenes RET and KIT. Lenvatinib has been approved by the US Food and Drug Administration (FDA) for the first-line treatment of hepatocellular carcinoma (HCC) due to its superior efficacy when compared to sorafenib. Unfortunately, the development of drug resistance to lenvatinib is becoming increasingly common. Thus, there is an urgent need to identify the factors that lead to drug resistance and ways to mitigate it. We summarize the molecular mechanisms that lead to lenvatinib resistance (LR) in HCC, which involve programmed cell death (PCD), translocation processes, and changes in the tumor microenvironment (TME), and provide strategies to reverse resistance.

Lenvatinib in hepatocellular carcinoma: Resistance mechanisms and strategies for improved efficacy

Hepatocellular carcinoma (HCC), one of the most prevalent and destructive causes of cancer-related deaths worldwide, approximately 70% of patients with HCC exhibit advanced disease at diagnosis, limiting the potential for radical treatment. For such patients, lenvatinib, a long-awaited alternative to sorafenib for first-line targeted therapy, has become a key treatment. Unfortunately, despite some progress, the prognosis for advanced HCC remains poor because of drug resistance development. However, the molecular mechanisms underlying lenvatinib resistance and ways to relief drug resistance in HCC are largely unknown and lack of systematic summary; thus, this review not only aims to explore factors contributing to lenvatinib resistance in HCC, but more importantly, summary potential methods to conquer or mitigate the resistance. The results suggest that abnormal activation of pathways, drug transport, epigenetics, tumour microenvironment, cancer stem cells, regulated cell death, epithelial-mesenchymal transition, and other mechanisms are involved in the development of lenvatinib resistance in HCC and subsequent HCC progression. To improve the therapeutic outcomes of lenvatinib, inhibiting acquired resistance, combined therapies, and nano-delivery carriers may be possible approaches.

N6-Methyladenosine Reader YTHDF1 Promotes Stemness and Therapeutic Resistance in Hepatocellular Carcinoma by Enhancing NOTCH1 Expression

N6-methyladenosine (m6A) RNA modification is the most common and conserved epigenetic modification in mRNA and has been shown to play important roles in cancer biology. As the m6A reader YTHDF1 has been reported to promote progression of hepatocellular carcinoma (HCC), it represents a potential therapeutic target. In this study, we evaluated the clinical significance of YTHDF1 using human HCC samples and found that YTHDF1 was significantly upregulated in HCCs with high stemness scores and was positively associated with recurrence and poor prognosis. Analysis of HCC spheroids revealed that YTHDF1 was highly expressed in liver cancer stem cells (CSC). Stem cell-specific conditional Ythdf1 knockin (CKI) mice treated with diethylnitrosamine showed elevated tumor burden as compared with wild-type mice. YTHDF1 promoted CSCs renewal and resistance to the multiple tyrosine kinase inhibitors lenvatinib and sorafenib in patient-derived organoids and HCC cell lines, which could be abolished by catalytically inactive mutant YTHDF1. Multiomic analysis, including RNA immunoprecipitation sequencing, m6A methylated RNA immunoprecipitation sequencing, ribosome profiling, and RNA sequencing identified NOTCH1 as a direct downstream of YTHDF1. YTHDF1 bound to m6A modified NOTCH1 mRNA to enhance its stability and translation, which led to increased NOTCH1 target genes expression. NOTCH1 overexpression rescued HCC stemness in YTHDF1-deficient cells in vitro and in vivo. Lipid nanoparticles targeting YTHDF1 significantly enhanced the efficacy of lenvatinib and sorafenib in HCC in vivo. Taken together, YTHDF1 drives HCC stemness and drug resistance through an YTHDF1-m6A-NOTCH1 epitranscriptomic axis, and YTHDF1 is a potential therapeutic target for treating HCC.

SIGNIFICANCE

Inhibition of YTHDF1 expression suppresses stemness of hepatocellular carcinoma cells and enhances sensitivity to targeted therapies, indicating that targeting YTHDF1 may be a promising therapeutic strategy for liver cancer.

Identification of Fasudil as a collaborator to promote the anti-tumor effect of lenvatinib in hepatocellular carcinoma by inhibiting GLI2-mediated hedgehog signaling pathway

Lenvatinib is a frontline tyrosine kinase inhibitor for patients with advanced hepatocellular carcinoma (HCC). However, just 25% of patients benefit from the treatment, and acquired resistance always develops. To date, there are neither effective medications to combat lenvatinib resistance nor accurate markers that might predict how well a patient would respond to the lenvatinib treatment. Thus, novel strategies to recognize and deal with lenvatinib resistance are desperately needed. In the current study, a robust Lenvatinib Resistance index (LRi) model to predict lenvatinib response status in HCC was first established. Subsequently, five candidate drugs (Mercaptopurine, AACOCF3, NU1025, Fasudil, and Exisulind) that were capable of reversing lenvatinib resistance signature were initially selected by performing the connectivity map (CMap) analysis, and fasudil finally stood out by conducting a series of cellular functional assays in vitro and xenograft mouse model. Transcriptomics revealed that the co-administration of lenvatinib and fasudil overcame lenvatinib resistance by remodeling the hedgehog signaling pathway. Mechanistically, the feedback activation of EGFR by lenvatinib led to the activation of the GLI2-ABCC1 pathway, which supported the HCC cell's survival and proliferation. Notably, co-administration of lenvatinib and fasudil significantly inhibited IHH, the upstream switch of the hedgehog pathway, to counteract GLI2 activation and finally enhance the effectiveness of lenvatinib. These findings elucidated a novel EGFR-mediated mechanism of lenvatinib resistance and provided a practical approach to overcoming drug resistance in HCC through meaningful drug repurposing strategies.

New Opportunities in the Systemic Treatment of Hepatocellular Carcinoma-Today and Tomorrow

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Liver cirrhosis, hepatitis B, hepatitis C, and non-alcoholic fatty liver disease represent major risk factors of HCC. Multiple different treatment options are available, depending on the Barcelona Clinic Liver Cancer (BCLC) algorithm. Systemic treatment is reserved for certain patients in stages B and C, who will not benefit from regional treatment methods. In the last fifteen years, the arsenal of available therapeutics has largely expanded, which improved treatment outcomes. Nevertheless, not all patients respond to these agents and novel combinations and drugs are needed. In this review, we aim to summarize the pathway of trials investigating the safety and efficacy of targeted therapeutics and immunotherapies since the introduction of sorafenib. Furthermore, we discuss the current evidence regarding resistance mechanisms and potential novel targets in the treatment of advanced HCC.

EGFR Inhibition Overcomes Resistance to FGFR4 Inhibition and Potentiates FGFR4 Inhibitor Therapy in Hepatocellular Carcinoma

Aberrant activation of the FGF19-FGFR4 signaling pathway plays an essential role in the tumorigenesis of hepatocellular carcinoma (HCC). As such, FGFR4 inhibition has emerged as a novel therapeutic option for the treatment of HCC and has shown preliminary efficacy in recent clinical trials for patients exhibiting aberrant FGF19 expression. Resistance to kinase inhibitors is common in oncology, presenting a major challenge in the clinical treatment process. Hence, we investigated the potential mechanisms mediating and causing resistance to FGFR4 inhibition in HCC. Upon the successful establishment of a battery of cellular models developing resistance to FGFR4 inhibitors, we have identified the activation of EGFR, MAPK, and AKT signaling as the primary mechanisms mediating the acquired resistance. Combination of inhibitors against EGFR or its downstream components restored sensitivity to FGFR4 inhibitors. In parental HCC cell lines, EGF treatment also resulted in resistance to FGFR4 inhibitors. This resistance was effectively reverted by inhibitors of the EGFR signaling pathway, suggesting that EGFR activation is a potential cause of intrinsic resistance. We further confirmed the above findings in vivo in mouse xenograft tumor models. Genomic analysis of patient samples from The Cancer Genome Atlas confirmed that a segment of patients with HCC harboring FGF19 overexpression indeed exhibited increased activation of EGFR signaling. These findings conclusively indicate that both induced and innate activation of EGFR could mediate resistance to FGFR4 inhibition, suggesting that dual blockade of EGFR and FGFR4 may be a promising future therapeutic strategy for the treatment of FGF19-FGFR4 altered HCC.

Targeting ACYP1-mediated glycolysis reverses lenvatinib resistance and restricts hepatocellular carcinoma progression

Acylphosphatase 1 (ACYP1), a protein located in the mammalian cell cytoplasm, has been shown to be associated with tumor initiation and progression by functioning as a metabolism-related gene. Here we explored the potential mechanisms by which ACYP1 regulates the development of HCC and participates in the resistance to lenvatinib. ACYP1 can promote the proliferation, invasion, and migration capacities of HCC cells in vitro and in vivo. RNA sequencing reveals that ACYP1 markedly enhances the expression of genes related to aerobic glycolysis, and LDHA is identified as the downstream gene of ACYP1. Overexpression of ACYP1 upregulates LDHA levels, which then increases the malignancy potential of HCC cells. GSEA data analysis reveals the enrichment of differentially expressed genes in the MYC pathway, indicating a positive correlation between MYC and ACYP1 levels. Mechanistically, ACYP1 exerts its tumor-promoting roles by regulating the Warburg effect through activating the MYC/LDHA axis. Mass spectrometry analysis and Co-IP assays confirm that ACYP1 can bind to HSP90. The regulation of c-Myc protein expression and stability by ACYP1 is HSP90 dependent. Importantly, lenvatinib resistance is associated with ACYP1, and targeting ACYP1 remarkably decreases lenvatinib resistance and inhibits progression of HCC tumors with high ACYP1 expression when combined with lenvatinib in vitro and in vivo. These results illustrate that ACYP1 has a direct regulatory role in glycolysis and drives lenvatinib resistance and HCC progression via the ACYP1/HSP90/MYC/LDHA axis. Targeting ACYP1 could synergize with lenvatinib to treat HCC more effectively.