Beth O. Van Emburgh et al., Acquired RAS or EGFR mutations and duration of response to EGFR blockade in colorectal cancer. Nature Communications

Beth O. Van Emburgh, Sabrina Arena, Giulia Siravegna, Luca Lazzari, Giovanni Crisafulli, Giorgio Corti, Benedetta Mussolin, Federica Baldi, Michela Buscarino, Alice Bartolini, Emanuele Valtorta, Joana Vidal, Beatriz Bellosillo, Giovanni Germano, Filippo Pietrantonio, Agostino Ponzetti, Joan Albanell, Salvatore Siena, Andrea Sartore-Bianchi, Federica Di Nicolantonio, Clara Montagut & Alberto Bardelli

Abstract:

Blockade of the epidermal growth factor receptor (EGFR) with the monoclonal antibodies cetuximab or panitumumab is effective in a subset of colorectal cancers (CRCs), but the emergence of resistance limits the efficacy of these therapeutic agents. At relapse, the majority of patients develop RAS mutations, while a subset acquires EGFRextracellular domain (ECD) mutations. Here we find that patients who experience greater and longer responses to EGFR blockade preferentially develop EGFR ECD mutations, while RAS mutations emerge more frequently in patients with smaller tumour shrinkage and shorter progression-free survival. In circulating cell-free tumour DNA of patients treated with anti-EGFR antibodies, RAS mutations emerge earlier than EGFR ECD variants. Subclonal RAS but not EGFR ECD mutations are present in CRC samples obtained before exposure to EGFR blockade. These data indicate that clonal evolution of drug-resistant cells is associated with the clinical outcome of CRC patients treated with anti-EGFR antibodies.

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