In patients with renal cell carcinoma (RCC) treated with a first-generation CAR-T against carbonic anhydrase IX (CAIX), some patients experienced liver enzyme disturbances that necessitated treatment cessation, a toxicity event that could be eliminated by pretreatment with an anti-CAIX monoclonal antibody [40]. The gene discussed is CA9; the disease is hereditary clear cell renal cell carcinoma.