Hepatocellular carcinoma (HCC) poses considerable therapeutic challenges, given that standard chemotherapies offer only restricted benefit. The mammalian target of rapamycin/sirolimus (mTOR) and microtubules represent two major druggable vulnerabilities in HCC. In this work, we demonstrated that concurrent mTOR inhibition with mTOR inhibitors (everolimus and sirolimus) and the microtubule inhibitor vinorelbine yielded outcomes superior to those of single-agent regimens in HCC PDX models. Our data indicate that vinorelbine halts cells in mitosis, promotes apoptosis, and restores a more normal vascular architecture within tumors, while simultaneously increasing survivin levels and activating the mTOR/p70S6K/4EBP1 signaling axis. Supplementing treatment with everolimus substantially augmented tumor sensitivity to vinorelbine, translating into extended overall survival (OS) across the majority of orthotopic HCC PDX models examined. Mechanistic dissection revealed that this pronounced tumor-suppressive effect correlated with diminished expression of mTOR effectors (p-p70S6K, p-4EBP1, and p-S6K), several pivotal cell-cycle regulatory proteins, and the anti-apoptotic factor survivin. Importantly, these molecular changes did not disrupt the vascular normalization elicited by vinorelbine in vinorelbine-responsive PDX models or by everolimus in everolimus-responsive PDX models. The pairing of everolimus with vinorelbine (everolimus/vinorelbine) also fostered apoptosis while exhibiting minimal toxicity. Given the affordability and documented clinical activity of everolimus and notably sirolimus, this combination strategy warrants further assessment in early-stage clinical trials.
