In addition, our findings highlight that FN1 was upregulated in recurrent chordomas compared with primary chordomas, and tumour cells, CD8 T cells, CD4 T cells and macrophages also secreted FN1 to promote the malignant progression of chordomas, demonstrating its ability to drive robust intercellular interactions within the TME of recurrent chordomas. The gene discussed is CD4; the disease is neoplasm.