High-affinity affibody binders have been selected for potential cancer-associated molecular targets such as human epidermal growth factor receptor type 2 (HER2) [22], epidermal growth factor receptor (EGFR or HER1) [23], human epidermal growth factor receptor type 3 (HER3) [24], insulin-like growth factor-1 receptor (IGF-1R) [25], platelet-derived growth factor receptor β (PDGFRβ) [26], vascular endothelial growth factor receptor 2 (VEGFR2) [27], programmed death-ligand 1 (PD-L1) [28], and carbonic anhydrase IX (CAIX) [29]. This evidence concerns the gene CA9 and cancer.