cetuximab + irinotecan + panitumumab

This is a combination regimen consisting of cetuximab, irinotecan, and panitumumab. Cetuximab and panitumumab are monoclonal antibodies that target the epidermal growth factor receptor (EGFR), inhibiting its signaling pathway, which is implicated in tumor cell proliferation and survival. Irinotecan is a small molecule chemotherapeutic agent that inhibits topoisomerase I, leading to DNA damage and apoptosis in rapidly dividing cells. This combination has been studied primarily for the treatment of metastatic colorectal cancer (mCRC) with wild-type KRAS genotype after failure of standard chemotherapy regimens including fluoropyrimidine, oxaliplatin, and irinotecan[5][2]. The use of both anti-EGFR antibodies together with irinotecan is not standard practice due to overlapping mechanisms; most clinical studies evaluate either cetuximab or panitumumab plus irinotecan rather than all three together[5][1]. Both monoclonal antibodies block EGFR but differ in their structure—cetuximab is a chimeric IgG1 antibody while panitumumab is a fully human IgG2 antibody—with subtle differences in immune activity[2].