To ensure an efficient drug delivery to tumor cells in an acidic TME, current clinical trials propose using combined therapies that target carbonic anhydrase and tumor cells, including the use of Acetazolamide and radiotherapy for small cell lung cancer treatment (NCT03467360), use of SLC-0111 and Gemcitabine for treatment of pancreatic ductal cancer positive for carbonic anhydrase IX (NCT03450018) and combination of Acetazolamide and Temozolomide for treatment of malignant glioma of brain (NCT03011671). The gene discussed is CA9; the disease is neoplasm.