With CAIX expression in healthy tissues being largely restricted to the small intestine and stomach (1,2,5,18), peptide-based therapeutic agents targeting CAIX, such as [177Lu]Lu-DPI-4452, provide the potential to target hypoxic or von Hippel-Lindau tumor suppressor–mutated tumors while featuring a favorable biodistribution (7,13). This evidence concerns the gene CA9 and neoplasm.