FOXD1 is a forkhead transcription factor that regulates diverse developmental processes including kidney morphogenesis, retinal patterning, and optic chiasm regionalization. The protein functions through sequence-specific DNA binding to modulate gene expression, including activation of inflammatory mediators such as PGF and C3 1. At the population level, FOXD1 is not classified as loss-of-function tolerant; however, its dysregulation—particularly upregulation—drives pathogenic phenotypes across multiple cancer contexts. In gastric intestinal metaplasia, FOXD1 suppression by miR-92a-1-5p promotes CDX2-driven intestinal differentiation through NF-κB pathway modulation 2. FOXD1 is upregulated in head and neck squamous carcinoma, where elevated expression correlates with poor overall survival and altered immune infiltration 3, and in nasopharyngeal carcinoma, where it enhances gemcitabine resistance by promoting mitophagy via BNIP3 transcriptional activation 4. In colorectal cancer metastasis, FOXD1 marks cancer stem cells enriched in liver metastases and predicts survival, especially in metastatic disease 5. In melanoma, FOXD1 reactivates neural crest programs to promote invasion and migration via RAC1B regulation 6, and drives immunosuppression by inducing IL-6-dependent myeloid-derived suppressor cell accumulation 7. Recent evidence suggests FOXD1 inhibition sensitizes medulloblastoma to immune checkpoint blockade by promoting chemokine release and CD8+ T cell recruitment 8, indicating therapeutic potential in combination immunotherapy.