Abstract: Lenvatinib (E7080) is a potent, oral, multi-target tyrosine kinase inhibitor (TKI) that exerts robust anti-tumor and anti-angiogenic effects by selectively inhibiting vascular endothelial growth factor receptors (VEGFR1-3), fibroblast growth factor receptors (FGFR1-4), platelet-derived growth factor receptor alpha (PDGFRα), RET, and KIT. While the target research direction of this review is endometrial cancer, the provided literature focuses exclusively on the pharmacological profile, clinical efficacy, and resistance mechanisms of lenvatinib in hepatocellular carcinoma (HCC), metastatic renal cell carcinoma (mRCC), and advanced thyroid cancers. Lenvatinib demonstrates a unique Type V binding mode (DFG-in conformation) that distinguishes it from other TKIs like sorafenib. Despite its significant clinical benefits, including immunomodulatory effects that reshape the tumor microenvironment, the efficacy of lenvatinib is frequently limited by adverse events and acquired drug resistance driven by epigenetic regulation, metabolic reprogramming, and altered regulated cell death (RCD) pathways. Future perspectives highlight the promising synergistic potential of combining lenvatinib with immune-checkpoint inhibitors (ICIs) and locoregional therapies, guided by emerging liquid biopsy biomarkers, to overcome resistance and improve patient survival.
1. Introduction
Lenvatinib (E7080) is an oral, multi-target tyrosine kinase inhibitor (TKI) that has emerged as a cornerstone therapeutic option in the management of various advanced malignancies [1]. It was initially established as a highly effective therapy for differentiated thyroid cancer [2]. Subsequently, based on the landmark REFLECT phase III trial, lenvatinib was approved as a first-line treatment for unresectable hepatocellular carcinoma (HCC), demonstrating non-inferior overall survival and superior progression-free survival (PFS) and objective response rates (ORR) compared to sorafenib [1][6]. Furthermore, it is approved in combination with everolimus for the treatment of metastatic renal cell carcinoma (mRCC) following prior anti-angiogenic therapy [2]. Although the specified research direction for this review is endometrial cancer, the provided literature does not contain data on this specific malignancy. Consequently, this review synthesizes the comprehensive data available in the provided texts regarding lenvatinib's molecular mechanisms, pharmacological activity, structure-activity relationships, and resistance mechanisms, which provide critical translational insights applicable across various solid tumors.
2. Pharmacological Activity
The pharmacological activity of lenvatinib is characterized by its dual ability to inhibit tumor angiogenesis and directly suppress tumor cell proliferation [1]. In highly vascularized tumors, lenvatinib induces hypoxia and nutrient starvation by suppressing the formation of new blood vessels. Interestingly, imaging studies reveal that lenvatinib induces early normalization of tumor blood volume (TBV) by reducing vessel diameter rather than destroying existing vascular structures [1].
Beyond its anti-angiogenic and anti-proliferative effects, lenvatinib exhibits profound immunomodulatory activity within the tumor immune microenvironment (TIME). Preclinical and clinical evidence indicates that lenvatinib decreases the frequency of immunosuppressive cells, such as regulatory T cells (Tregs) and tumor-associated macrophages, while significantly increasing the infiltration and activity of cytotoxic CD8+ T cells (including GZMK+ CD8+ T cells) [1]. Furthermore, lenvatinib alters the cytokine profile by increasing immunostimulatory factors (IL-2, IL-5, IFN-γ) and decreasing immunosuppressive factors (IL-6, IL-10, TNF-α) [1]. This immunomodulation provides a strong pharmacological rationale for combining lenvatinib with immunotherapies.
3. Molecular Mechanism of Action
Lenvatinib exerts its effects by simultaneously targeting multiple receptor tyrosine kinases. Its primary targets include VEGFR1-3, FGFR1-4, PDGFRα, RET, and KIT [1][2]. Tumor vascularization is heavily dependent on the VEGF/VEGFR signaling pathway. By binding to VEGFRs (particularly VEGFR2) on vascular endothelial cells, lenvatinib blocks downstream signaling cascades that promote angiogenesis [1].
A critical aspect of lenvatinib's mechanism is its concurrent inhibition of FGFR1-4. In many cancers, when the VEGF pathway is inhibited, the FGF/FGFR signaling pathway is upregulated as a compensatory escape mechanism to promote tumor angiogenesis and survival under nutrient-deprived conditions [1]. By dually targeting both VEGFR and FGFR, lenvatinib effectively shuts down this escape route, providing enhanced anti-tumor activity compared to agents that solely target VEGF signaling [1]. Additionally, lenvatinib inhibits RET phosphorylation and suppresses RET-ERK signaling, which is particularly relevant in tumors harboring RET genetic alterations [1].
4. Structure-Activity Relationship (SAR)
The structural interaction between lenvatinib and its target kinases dictates its high affinity and specificity. Structural elucidation of the lenvatinib-VEGFR2 and lenvatinib-FGFR1-4 complexes demonstrates that the drug interacts with the ATP-binding site and neighboring allosteric domains in a distinct conformation [1]. Specifically, lenvatinib binds to the kinase domain in the Asp-Phe-Gly "DFG-in" conformation [1].
Based on this unique binding mode, lenvatinib is categorized as a novel Type V kinase inhibitor [1]. This is a significant structural divergence from other TKIs, such as sorafenib, which binds to the "DFG-out" state of VEGFR2 and is classified as a Type II inhibitor [1]. These distinct molecular and structural characteristics account for the variations in kinase affinity profiles, pharmacological activities, and clinical efficacy observed between lenvatinib and other TKIs [1].
5. Current Limitations
Despite its efficacy, the clinical utility of lenvatinib is limited by adverse events and the inevitable development of drug resistance. Common treatment-emergent adverse events include hypertension, diarrhea, fatigue, proteinuria, decreased appetite, and weight loss [2][8]. These toxicities often necessitate dose reductions or treatment discontinuation, impacting overall patient compliance and survival [1].
Acquired resistance to lenvatinib is a complex, multifactorial process driven by several mechanisms:
- Receptor Activation and Pathway Crosstalk: Resistance can emerge through the hyperactivation of alternative pathways, such as the c-MET/Akt/ERK signaling axis or the EGFR-STAT3-ABCB1 axis, which enhances drug efflux and promotes cell survival [1][11].
- Epigenetic Regulation: Non-coding RNAs (ncRNAs) play a crucial role in resistance. For instance, the upregulation of circPIAS1 acts as a sponge for miR-455-3p, enhancing NUPR1 and FTH1 expression, which suppresses ferroptosis and confers resistance [11]. Similarly, the lncRNA HOTAIRM1 triggers autophagy to promote resistance [11].
- Regulated Cell Death (RCD): Tumor cells evade lenvatinib-induced death by altering RCD pathways, including apoptosis, autophagy, ferroptosis, cuproptosis, and pyroptosis [9]. While autophagy can sometimes act as a pro-survival mechanism for tumor cells under metabolic stress, its modulation presents a dualistic influence on resistance [9].
- Metabolic Reprogramming: Tumor-derived lactate can induce PD-L1 expression on neutrophils via the MCT1/NF-κB/COX-2 pathway, leading to an increase in Tregs and a reduction in T-cell cytotoxicity, thereby fostering an immunosuppressive microenvironment that blunts lenvatinib's efficacy [1].
6. Future Perspectives
To overcome resistance and maximize therapeutic outcomes, future strategies are heavily focused on combination regimens and biomarker-guided precision medicine. The combination of lenvatinib with immune-checkpoint inhibitors (ICIs), such as pembrolizumab or nivolumab, represents a major breakthrough [1][5]. Lenvatinib's ability to normalize tumor vasculature and reduce immunosuppressive cells synergizes with ICIs, enhancing T-cell infiltration and anti-tumor immunity, as evidenced by trials like KEYNOTE-524 and LEAP-002 [1][5]. Additionally, combining lenvatinib with other targeted agents (e.g., everolimus in mRCC) or locoregional therapies like transarterial chemoembolization (TACE) and hepatic arterial infusion chemotherapy (HAIC) has shown promising clinical potential [1][2][5].
Advancements in liquid biopsy and imaging will further refine lenvatinib therapy. Biomarkers such as circulating tumor DNA (ctDNA), FGFR4 expression, and the Albumin-Bilirubin (ALBI) grade are being investigated to predict patient response, monitor resistance dynamically, and tailor personalized treatment plans [1]. Continued exploration of these combination strategies and predictive biomarkers will be essential in expanding the clinical utility of lenvatinib across various solid tumors.
