SOX2 has the potential to serve as a biomarker for predicting the prognosis of CCA. Moreover, the PI3K/HDAC pathway can be considered as a target pathway for treating this disease. Furthermore, genes such as NNMT, GSTT1, SPTSSB, and RARRES1 might also be potential targets for therapeutic interventions. The gene discussed is HDAC9; the disease is cholangiocarcinoma.