PDGFRB and colorectal neoplasm: It was demonstrated that the combination of PDGFR and EGFR inhibitors (imatinib versus cetuximab) in colorectal tumor graft with mutant PDGFRA R981H (exon 22), identified as a mechanism of primary resistance to EGFR blockade, has a strong anti-tumor activity but with a short-lived effect [14].