Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide, with the majority of patients diagnosed at advanced stages where curative options are limited [
1]. The approval of lenvatinib, a tyrosine-kinase inhibitor (TKI) targeting VEGFR1–3, FGFR1–4, PDGFRα, RET, and KIT, as a first-line systemic therapy based on the landmark REFLECT trial represented a major advance in HCC management [
2]. Furthermore, a recent multicenter single-arm phase II trial demonstrated the clinical efficacy of lenvatinib in patients who progressed on firstline atezolizumab plus bevacizumab, highlighting its expanding utility as a viable later-line treatment option [
3].
However, the clinical benefit of lenvatinib is constrained by the inevitable emergence of acquired resistance, with disease progression occurring in the majority of patients within the first year of treatment [
4]. Elucidating the mechanisms underlying lenvatinib resistance is therefore a critical priority for improving outcomes in advanced HCC. Prior studies have primarily focused on tumor cell-intrinsic mechanisms of lenvatinib resistance. A seminal CRISPR-Cas9 screening study demonstrated that feedback activation of the EGFR-PAK2-ERK5 axis limits lenvatinib efficacy, providing the rationale for combining lenvatinib with EGFR inhibitors [
5]. This finding was subsequently translated into a phase II clinical trial of lenvatinib plus gefitinib in EGFR
high HCC, which demonstrated a promising 30% objective response rate [
6]. However, the contribution of the tumor microenvironment, particularly tumor-associated macrophages (TAMs), to acquired lenvatinib resistance has been comparatively underexplored [
7]. This represents a significant gap, as TAMs constitute a dominant immune cell population in the HCC microenvironment and have been shown to promote therapeutic resistance through diverse paracrine mechanisms across multiple treatment modalities [
8].
The study by Zhang et al. [
9] published in
Clinical and Molecular Hepatology provides mechanistic evidence that a previously uncharacterized COLEC12
high TAM subset orchestrates lenvatinib resistance and cancer stemness in HCC through paracrine NRG1-HER2/HER3 signaling [
9]. This work provides an important conceptual advance by placing macrophage-derived paracrine signaling at the center of acquired TKI resistance in HCC. The authors employed an integrative approach, combining transcriptomic profiling of paired treatment-naïve and lenvatinib-resistant tumors from both patients and murine models. Single-cell RNA sequencing revealed a marked enrichment of COLEC12
high TAMs in resistant tumors, distinguishing them from the broader macrophage population. Functionally, conditioned medium from COLEC12
high TAMs was sufficient to confer lenvatinib resistance and augment cancer stemness in HCC cells, while depletion of this subset restored drug sensitivity. Through unbiased CRISPR-based synergistic activation mediator screening coupled with conditioned medium assays, the authors identified neuregulin 1 (NRG1) as the critical paracrine factor. NRG1 binding to HER3 on tumor cells triggers HER2/HER3 heterodimerization and downstream AKT signaling, thereby sustaining proliferative and stemness programs that override lenvatinib’s anti-tumor effects.
An important aspect of this study is the dissection of the intracellular mechanism related to NRG1 upregulation within TAMs. The authors demonstrated that COLEC12 physically sequesters STAT1 in the cytoplasm, preventing its phosphorylation and nuclear translocation. Under general states, phosphorylated STAT1 acts as a transcriptional repressor of NRG1 by competing with STAT3 at the NRG1 promoter. When COLEC12 blocks STAT1 nuclear entry, STAT3-mediated NRG1 transcription proceeds unopposed. This COLEC12-STAT1/STAT3 regulatory switch represents a novel mechanism linking a scavenger receptor to JAKSTAT signaling in TAMs and provides a molecular explanation for how a single surface molecule can reprogram macrophage secretory functions to promote treatment resistance.
The clinical validation further strengthens the translational relevance of these findings. In a cohort of 50 HCC patients treated with lenvatinib, high NRG1 expression was associated with significantly shorter progression-free survival and inferior objective response rates. This positions NRG1 as a potential predictive biomarker for lenvatinib response, addressing a critical unmet need in the field, as no reliable molecular predictor of TKI efficacy currently exists in HCC [
10]. Importantly, immunohistochemical staining of COLEC12 and NRG1 expression could potentially be incorporated into routine clinical workflows to guide treatment selection.
Of note, the most translatable implication of this study is the repurposing of zenocutuzumab, a bispecific anti-HER2/HER3 antibody originally developed for NRG1 fusion-positive cancers. The recent accelerated United States Food and Drug Administration (FDA) approval of zenocutuzumab for NRG1 fusion-positive non-small cell lung cancer and pancreatic adenocarcinoma, based on the eNRGy trial demonstrating a 30% response rate with a median duration of response exceeding 11 months [
11], establishes clinical precedent for targeting the NRG1-HER2/HER3 axis. The current study extends this therapeutic concept to a fundamentally different biological context: rather than targeting constitutive NRG1 signaling driven by an oncogenic fusion, zenocutuzumab is deployed to intercept paracrine NRG1 secreted by TAMs in the resistant microenvironment. The authors demonstrated that zenocutuzumab restores lenvatinib sensitivity in patient-derived organoids, patient-derived xenografts, and syngeneic murine models. The emerging understanding of HER3 as a broadly relevant therapeutic target across diverse tumor contexts further supports this approach [
12].
In addition, this study further elucidates the complex landscape of TAM subpopulations in HCC. Previous work has identified functionally distinct macrophage subsets, including TREM2
+ TAMs that trigger mucosal-associated invariant T (MAIT) cell dysfunction at the invasive margin and SPP1
+ macrophages within onco-fetal niches that drive immunosuppression [
13]. The identification of COLEC12
high TAMs as a resistance-promoting subset enriches this landscape and supports the broader trend toward surface markerbased stratification of myeloid cells for prognostic and therapeutic purposes. Notably, while prior studies have established TAM roles in sorafenib resistance through hepatocyte growth factor secretion and in immune checkpoint inhibitor resistance through programmed death-ligand 1 (PD-L1) upregulation, the current study is among the first to delineate a specific TAM subset driving TKI resistance through a defined paracrine signaling axis.
Several important questions warrant further investigation. First, the clinical validation cohort of 50 patients, while informative, is relatively modest, and prospective validation in larger, multi-center cohorts would be necessary to establish NRG1 as a clinically actionable biomarker. Second, whether COLEC12high TAMs also contribute to resistance against immune checkpoint inhibitor-based combinations such as atezolizumab-bevacizumab or durvalumab-tremelimumab warrants further investigation. Third, the upstream signals governing COLEC12 upregulation in TAMs during lenvatinib treatment remain unclear; identifying these triggers would illuminate how the resistant microenvironment is initially established. Finally, understanding potential mechanisms of resistance to the lenvatinib-zenocutuzumab combination would be critical to anticipate escape pathways before clinical translation.
In conclusion, the study by Zhang et al. [
9] establishes a substantial contribution by identifying COLEC12
high TAMs as key orchestrators of lenvatinib resistance through a previously unrecognized paracrine NRG1-HER2/HER3 signaling axis. The convergence of a novel resistance mechanism, a clinically actionable biomarker, and an FDA-approved therapeutic agent targeting the same pathway makes this work particularly noteworthy. Future clinical trials evaluating lenvatinib in combination with zenocutuzumab or other HER2/HER3-targeting agents in molecularly selected HCC patients would suggest a rational next step for biomarkerdriven clinical investigation.
FOOTNOTES
-
Authors’ contribution
Ji Won Han was responsible for conceptualization, literature review, writing of the original draft, critical revision, and approval of the final manuscript.
-
Acknowledgements
This research was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant No. RS-2024-00406716 to JWH).
-
Conflicts of Interest
The authors have no conflicting financial interests.
Abbreviations
United States Food and Drug Administration
mucosal-associated invariant T
programmed death-ligand 1
tumor-associated macrophages
tyrosine-kinase inhibitor
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