This analysis has highlighted, for the first time, the use of metformin as a negative prognostic factor in a cohort of patients who received atezolizumab plus bevacizumab for advanced HCC. Conversely, the utilization of metformin was found to have no prognostic impact in a cohort of patients with advanced HCC who received Lenvatinib as a first-line treatment. Recently, Kang and colleagues performed an analysis on a cohort of patients treated with immunotherapy for advanced HCC and highlighted worse survival outcomes in patients included in the metformin group compared to those in the no-metformin groups, even without reaching the statistical significance (11). Our study encompassed a larger patient sample receiving first-line treatment for advanced HCC (Atezolizumab plus Bevacizumab or Lenvatinib), whereas the previous study focused exclusively on patients who received immunotherapy in either the first or subsequent lines of treatment. However, our findings provide substantial support, based on a larger patient cohort, to the notion that individuals receiving immunotherapy for advanced HCC and using metformin as a chronic medication exhibit inferior survival outcomes when compared to those not taking metformin chronically. Preclinical evidence provides a biological rationale for the anticancer properties of metformin. Metformin has been demonstrated to improve the restoring of CD8 + tumor infiltrating lymphocytes (TILs) from immune exhaustion (12)and to reduce hypoxic status in tumor microenvironment and improve intra-tumoral T cell function (13). In addition, metformin could inhibit the differentiation of naïve CD4 + T cells into regulatory T cells (Tregs), thus blocking the activation of myeloid-derived suppressor cells (MDSCs) and reverting the M2-like polarization of tumor associated macrophages (TAMs) (14). hese evidence seems to suggest that the combination of immunotherapy and metformin could act in synergism and potentially enhancing the anticancer response. In the field of HCC, additional factors contribute to shaping the overall scenario. Unlike other oncologic diseases, HCC develops within the context of hepatopathy, which can have various underlying etiologies. These different etiologies have been shown to exert distinct effects on the immune microenvironment, resulting in diverse carcinogenic pathways (4–7). In addition both preclinical and retrospective clinical data support the hypothesis that patients with MASH-related HCC could be less responsive to immune checkpoint inhibitors (7). Wabitsch and colleagues recently confirmed that patients with MASH-related HCC are less responsive to immunotherapy, due to aberrant activation and exhaustion of CD8 + T cells (15). In the same work, authors demonstrated that metformin treatment restores the motility and metabolism of CD8 + T cells, thus enhancing the anti-tumor immune responses (15), which is inconsistent with the present analysis. As expected, in our analysis the proportion of MASH-related HCC in the metformin-group of patients is higher, which could have influenced the results reported. Nevertheless, after correction for etiology, the multivariate analysis confirmed the negative prognostic factor of the chronic use of metformin in the cohort of patients who received Atezolizumab plus BevacizumabConcerning the absence of prognostic impact of metformin use in patients who received Lenvatinib, several considerations could be done. In a previous work, the concomitant use of metformin and sorafenib was associated with worse OS and PFS in a cohort of patients affected by advanced HCC, due to a competitive action on PI3K and MAPK signaling exerted by metformin, which leads to the development of resistance to sorafenib (16, 17). Although belonging to the same class of drugs, Lenvatinib and Sorafenib present different target spectra, which could explain the varying results when combined with metformin. In a recent work, Chen and colleagues showed that Lenvatinib and Metformin both suppress the activation of AKT signaling pathway thus leading to the nuclear aggregation of downstream effector FOXO3. Finally, interactions between metformin and oncologic treatments depend also to the timing, since the pathways and, consequently, the biological behavior of an HCC arising in a patient already treated with metformin is different from that of an HCC arising in a patient who, at some point, undergoes treatment with metformin.
The present study has several limitations, primarily stemming from its retrospective and multicenter nature. Selection bias among patients cannot be entirely ruled out, and it's important to consider the absence of centralized imaging review for the evaluation of PFS. Finally, data about doses and schedule of use of metformin as well as data on concomitant medications for diabetes were unavailable, due to the large retrospective and multicentric design of the study. Further investigations and prospective validations on external cohort are needed in order to verify our results. Nevertheless the present study represents the first analysis focusing on the role of metformin in a large cohort of patients with advanced HCC, who underwent first-line therapy with either Lenvatinib or Atezolizumab plus Bevacizumab. This analysis unveils a negative prognostic role associated with metformin use specifically within the Atezolizumab plus Bevacizumab group. Our findings corroborated in a larger sample size the earlier study by Kang and colleagues adding a crucial piece to the complex puzzle of the interaction between metformin and immunotherapy for patients dealing with advanced HCC.