title: Clonal evolution and resistance to EGFR blockade in the blood of colorectal cancer patients.
abstract: Colorectal cancers (CRCs) evolve by a reiterative process of genetic diversification and clonal evolution. The molecular profile of CRC is routinely assessed in surgical or bioptic samples. Genotyping of CRC tissue has inherent limitations; a tissue sample represents a single snapshot in time, and it is subjected to spatial selection bias owing to tumor heterogeneity. Repeated tissue samples are difficult to obtain and cannot be used for dynamic monitoring of disease progression and response to therapy. We exploited circulating tumor DNA (ctDNA) to genotype colorectal tumors and track clonal evolution during treatment with the epidermal growth factor receptor (EGFR)-specific antibodies cetuximab or panitumumab. We identified alterations in ctDNA of patients with primary or acquired resistance to EGFR blockade in the following genes: KRAS, NRAS, MET, ERBB2, FLT3, EGFR and MAP2K1. Mutated KRAS clones, which emerge in blood during EGFR blockade, decline upon withdrawal of EGFR-specific antibodies, indicating that clonal evolution continues beyond clinical progression. Pharmacogenomic analysis of CRC cells that had acquired resistance to cetuximab reveals that upon antibody withdrawal KRAS clones decay, whereas the population regains drug sensitivity. ctDNA profiles of individuals who benefit from multiple challenges with anti-EGFR antibodies exhibit pulsatile levels of mutant KRAS. These results indicate that the CRC genome adapts dynamically to intermittent drug schedules and provide a molecular explanation for the efficacy of rechallenge therapies based on EGFR blockade.
authors.affiliation: 1] University of Torino, Department of Oncology, Torino, Italy. [2] Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy. [3] Fondazione Italiana per la Ricerca sul Cancro (FIRC) Institute of Molecular Oncology (IFOM), Milano, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Siravegna
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Mussolin
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Buscarino
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Giorgio
authors.identifier: 0000000163794117
authors.initials: G
authors.lastname: Corti
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cassingena
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Crisafulli
authors.affiliation: Colorectal Cancer Unit, Medical Oncology Division 1, AOU Città della Salute e della Scienza, San Giovanni Battista Hospital, Turin, Italy.
authors.forename: Agostino
authors.initials: A
authors.lastname: Ponzetti
authors.affiliation: Azienda Ospedaliero-Universitaria Pisana and Università di Pisa, Pisa.
authors.forename: Chiara
authors.initials: C
authors.lastname: Cremolini
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Alessio
authors.identifier: 0000000153963378
authors.initials: A
authors.lastname: Amatu
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Calogero
authors.initials: C
authors.lastname: Lauricella
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Lamba
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Sebastijan
authors.initials: S
authors.lastname: Hobor
authors.affiliation: Istituto Nazionale Tumori Fondazione G. Pascale - IRCCS, Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Avallone
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Valtorta
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rospo
authors.affiliation: 1] University of Torino, Department of Oncology, Torino, Italy. [2] Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Enzo
authors.initials: E
authors.lastname: Medico
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Motta
authors.affiliation: Azienda Ospedaliero-Universitaria Pisana and Università di Pisa, Pisa.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Antoniotti
authors.affiliation: Istituto Nazionale Tumori Fondazione G. Pascale - IRCCS, Naples, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Tatangelo
authors.affiliation: Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Bellosillo
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Veronese
authors.affiliation: Istituto Nazionale Tumori Fondazione G. Pascale - IRCCS, Naples, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Budillon
authors.affiliation: Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Montagut
authors.affiliation: Colorectal Cancer Unit, Medical Oncology Division 1, AOU Città della Salute e della Scienza, San Giovanni Battista Hospital, Turin, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Racca
authors.affiliation: Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Marsoni
authors.affiliation: Azienda Ospedaliero-Universitaria Pisana and Università di Pisa, Pisa.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Falcone
authors.affiliation: Massachusetts General Hospital Cancer Center, Boston, Massachusetts.
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Corcoran
authors.affiliation: 1] University of Torino, Department of Oncology, Torino, Italy. [2] Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Federica
authors.identifier: 0000000196182010
authors.initials: F
authors.lastname: Di Nicolantonio
authors.affiliation: Azienda Ospedaliero-Universitaria Pisana and Università di Pisa, Pisa.
authors.forename: Fotios
authors.initials: F
authors.lastname: Loupakis
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Siena
authors.affiliation: Niguarda Cancer Center, Ospedale Niguarda Ca' Granda, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Sartore-Bianchi
authors.affiliation: 1] University of Torino, Department of Oncology, Torino, Italy. [2] Candiolo Cancer Institute - Fondazione Piemontese per l'Oncologia (FPO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Candiolo, Torino, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Bardelli
mesh_terms: D000483:Alleles; D000906:Antibodies / Q000494:pharmacology / Q000627:therapeutic use; D000912:Antibodies, Neoplasm / Q000097:blood; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D060965:Clonal Evolution; D002999:Clone Cells; D015179:Colorectal Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D004273:DNA, Neoplasm / Q000097:blood; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000276:immunology; D006801:Humans; D009154:Mutation / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics
chemical_list: D000906:Antibodies; D000912:Antibodies, Neoplasm; D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D066246:ErbB Receptors; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins