Each agent here is a targeted oncology drug defined by the kinase or receptor it blocks. Sunitinib is an oral multi-targeted inhibitor that hits VEGFR, PDGFR and $c\text{-}KIT$, which is why it works in renal cell carcinoma and in imatinib-resistant gastrointestinal stromal tumours. Nilotinib is a more potent second-generation inhibitor of the $BCR\text{-}ABL$ fusion kinase and is used in chronic myeloid leukaemia. Trastuzumab is a humanised monoclonal antibody directed at the $HER2$ receptor on breast and gastric cancers. Gefitinib is a small-molecule inhibitor of $EGFR$ tyrosine kinase used in EGFR-mutant lung cancer. Pairing them gives Sunitinib with c-KIT, Nilotinib with BCR-ABL, Trastuzumab with HER2 and Gefitinib with EGFR, and only the first option keeps all four correct while the others swap targets.
\[\boxed{\text{Sunitinib-cKIT, Nilotinib-BCRABL, Trastuzumab-HER2, Gefitinib-EGFR}}\]