Targeted therapy is a groundbreaking innovation for cancer treatment. Among the receptor tyrosine kinases, the fibroblast growth factor receptors (FGFRs) garnered substantial attention as promising therapeutic targets due to their fundamental biological functions and frequently observed abnormality in tumors. In the past 2 decades, several generations of FGFR kinase inhibitors have been developed. This review starts by introducing the biological basis of FGF/FGFR signaling. It then gives a detailed description of different types of small-molecule FGFR inhibitors according to modes of action, followed by a systematic overview of small-molecule-based therapies of different modalities. It ends with our perspectives for the development of novel FGFR inhibitors.

Activation of invasion and metastasis is a central hallmark of cancer, contributing to the primary cause of death for patients with cancer. In the multistep metastatic process, cancer cells must infiltrate the circulation, survive, arrest at capillary beds, extravasate, and form metastatic clones in distant organs. However, only a small proportion of circulating tumor cells (CTC) successfully form metastases, with transit of CTCs in the circulation being the rate-limiting step. The fate of CTCs is influenced by the circulating tumor microenvironment (cTME), which encompasses factors affecting their biological behaviors in the circulation. This liquid and flowing microenvironment differs significantly from the primary TME or the premetastatic niche. This review summarizes the latest advancements in identifying the biophysical cues, key components, and biological roles of the cTME, highlighting the network among biophysical attributes, blood cells, and nonblood factors in cancer metastasis. In addition to the potential of the cTME as a therapeutic target for inhibiting metastasis, the cTME could also represent as a biomarker for predicting patient outcomes and developing strategies for treating cancer.

Breast cancer (BC) is a common malignant tumor in women and requires a comprehensive understanding of its pathogenesis for the development of new therapeutic strategies. Polyunsaturated fatty acids (PUFAs) metabolism-driven inflammation is a causative factor in cancer development. However, the function of PUFAs′ metabolism in BC remains largely unknown. Here we report the role and underlying mechanism of epoxyoctadecenoic acids (EpOMEs), the metabolites of linoleic acid mediated by cytochrome P450 (CYP) monooxygenases, in promoting the development of BC, particularly triple-negative BC (TNBC). A metabolomics study identified that EpOMEs were significantly increased in the plasma of BC patients and MMTV-PyMT mice, which accounted for the upregulation of CYP2J2 in BC tumor tissues and tumor cells. Decreased EpOMEs by treatment of CYP monooxygenase inhibitors significantly alleviated tumor development in MMTV-PyMT mice. Treatment with EpOMEs and overexpression of CYP2J2 to increase EpOMEs in TNBC cells significantly promoted cellular proliferation, migration, tumor growth, and metastasis. Whereas knockdown of CYP2J2 to decrease EpOMEs inhibited tumorigenesis and lung metastasis of TNBC, which was reversed by EpOME administration. Transcriptomics and proteomics analyses revealed CXCL9 and PLEC were critical for EpOME-mediated promotion of TNBC. Knockdown of CXCL9 and PLEC inhibited TNBC progression and EpOME-mediated promotion of TNBC. Both overexpression of CYP2J2 and EpOME treatment upregulate PLEC, while PLEC upregulates NFκB1, which is a transcription regulator of CXCL9. This study extends the understanding of the function of PUFAs metabolism in BC development, providing potential therapeutic targets and dietary guidelines for patients with TNBC and other BCs.

Background: The peptidyl–prolyl cis–trans isomerase PIN1 regulates multiple oncogenic and tumor-suppressive pathways and is frequently overexpressed in human cancers. Although pharmacological inhibition of PIN1 has shown antitumor potential, existing PIN1-targeting degraders lack systematic structure–activity relationship (SAR) analyses and display inconsistent cellular efficacy, leaving the therapeutic relevance of PIN1 degradation unclear. Methods: Two series of PIN1-targeting PROTACs were designed using the covalent inhibitor sulfopin as the PIN1 binder and ligands for either cereblon (CRBN) or von Hippel–Lindau (VHL). Systematic SAR studies focused on linker structure and jointing atom composition. PIN1 degradation was assessed by Western blotting in multiple cancer cell lines, and further investigated through a series of computational and mechanistic experiments. Antitumor efficacy and safety were evaluated in an MCF-7 xenograft mouse model with preliminary pharmacokinetic analysis. Results: SAR analysis revealed that short, linear linkers and reduced hydrogen bond donor content markedly enhanced PIN1 degradation, whereas VHL-recruiting PROTACs showed inferior cellular activity. These studies identified PC2, a CRBN-recruiting PROTAC, as a lead compound. PC2 selectively induced ubiquitin–proteasome-dependent PIN1 degradation with minimal global proteomic or transcriptomic perturbation. Despite modest antiproliferative effects in vitro, PC2 significantly suppressed tumor growth in vivo without observable toxicity and achieved effective intratumoral PIN1 degradation. Conclusions: This study defines SAR-guided design principles for PIN1-targeting PROTACs and demonstrates that selective PIN1 degradation can produce robust antitumor activity in vivo. PC2 represents the first PIN1 degrader validated in animal models and supports targeted PIN1 degradation as a viable anticancer strategy.