Cancer-associated fibroblasts (CAF) may exert tumor-promoting and tumor-suppressive functions, but the mechanisms underlying these opposing effects remain elusive. Here, we sought to understand these potentially opposing functions by interrogating functional relationships among CAF subtypes, their mediators, desmoplasia, and tumor growth in a wide range of tumor types metastasizing to the liver, the most common organ site for metastasis. Depletion of hepatic stellate cells (HSC), which represented the main source of CAF in mice and patients in our study, or depletion of all CAF decreased tumor growth and mortality in desmoplastic colorectal and pancreatic metastasis but not in nondesmoplastic metastatic tumors. Single-cell RNA-Seq in conjunction with CellPhoneDB ligand-receptor analysis, as well as studies in immune cell–depleted and HSC-selective knockout mice, uncovered direct CAF-tumor interactions as a tumor-promoting mechanism, mediated by myofibroblastic CAF–secreted (myCAF-secreted) hyaluronan and inflammatory CAF–secreted (iCAF-secreted) HGF. These effects were opposed by myCAF-expressed type I collagen, which suppressed tumor growth by mechanically restraining tumor spread, overriding its own stiffness-induced mechanosignals. In summary, mechanical restriction by type I collagen opposes the overall tumor-promoting effects of CAF, thus providing a mechanistic explanation for their dual functions in cancer. Therapeutic targeting of tumor-promoting CAF mediators while preserving type I collagen may convert CAF from tumor promoting to tumor restricting.

Immune checkpoint therapy via PD-1 antibodies has shown exciting clinical value and robust therapeutic potential in clinical practice. It can significantly improve progression-free survival and overall survival. Following surgery, radiotherapy, chemotherapy, and targeted therapy, cancer treatment has now entered the age of immunotherapy. Although cancer immunotherapy has shown remarkable efficacy, it also suffers from limitations such as irAEs, cytokine storm, low response rate, etc. In this review, we discuss the basic classification, research progress, and limitations of cancer immunotherapy. Besides, by combining cancer immunotherapy resistance mechanism with analysis of combination therapy, we give our insights into the development of new anticancer immunotherapy strategies.

The overall response rate for anti–PD-1 therapy remains modest in hepatocellular carcinoma (HCC). We found that a combination of IFNα and anti–PD-1–based immunotherapy resulted in enhanced antitumor activity in patients with unresectable HCC. In both immunocompetent orthotopic and spontaneous HCC models, IFNα therapy synergized with anti–PD-1 and the combination treatment led to significant enrichment of cytotoxic CD27+CD8+ T cells. Mechanistically, IFNα suppressed HIF1α signaling by inhibiting FosB transcription in HCC cells, resulting in reduced glucose consumption capacity and consequentially establishing a high-glucose microenvironment that fostered transcription of the T-cell costimulatory molecule Cd27 via mTOR–FOXM1 signaling in infiltrating CD8+ T cells. Together, these data reveal that IFNα reprograms glucose metabolism within the HCC tumor microenvironment, thereby liberating T-cell cytotoxic capacities and potentiating the PD-1 blockade–induced immune response. Our findings suggest that IFNα and anti–PD-1 cotreatment is an effective novel combination strategy for patients with HCC. Significance: Our study supports a role of tumor glucose metabolism in IFNα-mediated antitumor immunity in HCC, and tumor-infiltrating CD27+CD8+ T cells may be a promising biomarker for stratifying patients for anti–PD-1 therapy. See related commentary by Kao et al., p. 1615. This article is highlighted in the In This Issue feature, p. 1599

Pharmacological inhibition of β-catenin/BCL9 interaction modulates T _reg cells and improves immunotherapy.