Dual Ferroptosis Strategy Dismantles Liver Cancer's Immune Shield in Mice
A nanoparticle co-delivering sorafenib and an FSP1 inhibitor kills both tumor cells and immunosuppressive macrophages, reviving anti-tumor immunity.
Summary
Researchers engineered biomimetic nanoparticles (Sv@PM-M2p) that simultaneously deliver sorafenib (SF) and the FSP1 inhibitor viFSP1 to hepatocellular carcinoma (HCC) cells and immunosuppressive M2 tumor-associated macrophages (TAMs). By blocking both GPX4 and FSP1 — two independent ferroptosis defense pathways — the nanoplatform triggers lipid peroxide accumulation and ferroptotic death in both cell types. This dual action releases immunostimulatory damage signals, promotes dendritic cell maturation and CD8+ T cell infiltration, and remodels the tumor microenvironment from immunosuppressive to immunostimulatory. Combined with anti-PD-L1 antibody therapy, the approach suppressed tumor growth, metastasis, and recurrence across multiple preclinical HCC mouse models, including immune-humanized patient-derived xenografts from etiologically distinct HCCs.
Detailed Summary
Hepatocellular carcinoma (HCC) remains one of the deadliest cancers globally, partly because its tumor microenvironment (TME) is profoundly immunosuppressive. M2-polarized tumor-associated macrophages (TAMs) are among the most abundant immunosuppressive cells in HCC, secreting TGF-β and IL-10 to blunt anti-tumor immunity. Sorafenib (SF), the first-line systemic therapy for HCC, induces ferroptosis by inhibiting the SLC7A11–GPX4 axis, but its clinical efficacy is limited by resistance mechanisms and poor bioavailability.
This study identifies a key resistance mechanism: upregulation of ferroptosis suppressor protein 1 (FSP1), which independently of GPX4 converts ubiquinone and vitamin K to their hydroquinone forms, neutralizing lipid peroxides and blocking ferroptosis. Bioinformatic analysis of multiple single-cell RNA sequencing datasets from HBV-driven and non-viral HCC patients confirmed that FSP1 is enriched in both tumor cells and M2 TAMs, correlates with increased immunosuppressive TAM infiltration, and predicts poor prognosis. Critically, SF treatment itself upregulated FSP1, creating a feedback resistance loop.
To overcome this, the researchers developed Sv@PM-M2p — a GSH-responsive, biomimetic nanoparticle built from a disulfide-bond-linked PLGA polymer core co-loaded with SF and the species-independent FSP1 inhibitor viFSP1 (vF), coated with isolated HCC cell membranes conjugated with M2 macrophage-binding peptide (M2pep). This dual-targeting design exploits HCC membrane-mediated homologous homing to tumor cells and M2pep-mediated recognition of M2 TAMs. Upon internalization, elevated intracellular GSH cleaves the disulfide bonds, releasing both drugs to simultaneously inhibit GPX4 and FSP1, deplete GSH, and drive lipid peroxidation — inducing ferroptosis in both HCC cells and M2 TAMs.
In vitro, the combination of SF and vF at low doses produced synergistic ferroptotic cell death in human and murine HCC lines and in M2-polarized macrophages, confirmed by lipid peroxide accumulation, mitochondrial morphology changes, and cell death assays. Ferroptotic cells released damage-associated molecular patterns (DAMPs), promoted dendritic cell maturation, and enhanced macrophage phagocytosis. In vivo, Sv@PM-M2p demonstrated superior tumor accumulation and penetration in CDX and allograft HCC models, significantly inhibiting tumor growth while remodeling the TME: reducing M2 TAMs, increasing M1 macrophages, and boosting CD8+ cytotoxic T cell infiltration. Combining Sv@PM-M2p with anti-PD-L1 antibody further suppressed distant metastasis and tumor recurrence, establishing durable anti-tumor immunity. In immune-humanized PDX models representing HBV-driven and non-viral HCC, Sv@PM-M2p outperformed current first-line clinical regimens.
This work establishes a compelling proof-of-concept for dual-pathway ferroptosis induction as a strategy to simultaneously kill cancer cells and dismantle their immunosuppressive macrophage support network, with synergistic benefit from checkpoint blockade. The approach is notable for its translational design — using clinically approved SF, a well-characterized FSP1 inhibitor, and a biomimetic nanocarrier — though it remains preclinical and requires validation in human trials.
Key Findings
- FSP1 upregulation after sorafenib treatment drives ferroptosis resistance and correlates with M2 TAM infiltration and poor HCC prognosis.
- Biomimetic nanoparticles Sv@PM-M2p co-deliver SF and viFSP1 to both HCC cells and M2 TAMs via dual-targeting mechanisms.
- Dual GPX4 + FSP1 inhibition triggers synergistic ferroptosis in tumor cells and immunosuppressive macrophages, releasing immunostimulatory DAMPs.
- Combined Sv@PM-M2p and anti-PD-L1 antibody suppressed metastasis and tumor recurrence in mouse HCC models.
- Sv@PM-M2p outperformed first-line clinical therapies in immune-humanized PDX models of etiologically distinct HCC.
Methodology
The study combined bioinformatic analysis of multiple scRNA-seq datasets (GSE149614, GSE156337, SRP318499, GSE202642) with in vitro ferroptosis assays in HCC cell lines and M2 macrophages, and in vivo testing in CDX, syngeneic allograft, and immune-humanized PDX mouse models. Nanoparticle characterization included GSH-responsive drug release, dual-targeting validation, and TME immune profiling by flow cytometry and immunohistochemistry.
Study Limitations
All efficacy data are from mouse models; human clinical validation is absent. The FSP1 inhibitor viFSP1 has not yet been clinically approved, and long-term toxicity of the nanoplatform is not fully characterized. The immune-humanized PDX models, while more translatable, still imperfectly recapitulate the human immune system.
Enjoyed this summary?
Get the latest longevity research delivered to your inbox every week.