title: Deciphering intra-tumor heterogeneity of lung adenocarcinoma confirms that dominant, branching, and private gene mutations occur within individual tumor nodules.
abstract: While pulmonary adenocarcinoma (ADC) is morphologically heterogeneous, little is known about intra-tumor gene mutation heterogeneity (ITH). We therefore subjected 20 ADC nodules, 5 mutated for EGFR and 5 for KRAS, 5 with an ALK translocation, and 5 wild type (WT) for these alterations, to unsupervised next-generation sequencing of tumor regions from diverse architectural patterns. When 2 or more different gene mutations were found in a single tumor, this fulfilled the criteria for ITH. In the 84 studied tumor regions with diverse architecture, 71 gene mutations and 34 WT profiles were found. ITH was observed in 9/15 (60 %) ADC, 3 with an EGFR, 3 with a KRAS, and 3 with an ALK aberration, as reflected in 5, 6, and 9 additional mutations, respectively, detected in these tumors. EGFR mutations were observed in 21/22 and KRAS mutations in 18/22 tumor regions, suggesting that they appear early and have a driver role (dominant or trunk mutations). Branching mutations (in EZH2, PIK3CA, TP53, and EGFR exon 18) occurred in two or more regions, while private mutations (in ABL1, ALK, BRAF, HER2, KDR, LKB1, PTEN, MET, SMAD4, SMARCB1, and SRC) were confined to unique tumor samples of individual lesions, suggesting that they occurred later on during tumor progression. Patients with a tumor showing branching mutations ran a worse clinical course, independent of confounding factors. We conclude that in ADC, ITH exists in a pattern suggesting spatial and temporal hierarchy with dominant, branching, and private mutations. This is consistent with diverse intra-tumor clonal evolution, which has potential implications for patient prognosis or development of secondary therapy resistance.
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy. giuseppe.pelosi@unimi.it.|Department of Biomedical and Clinical Sciences "Luigi Sacco", Università degli Studi, Milan, Italy. giuseppe.pelosi@unimi.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pelosi
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Pellegrinelli
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Fabbri
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Tamborini
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Perrone
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Settanni
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Adele
authors.initials: A
authors.lastname: Busico
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Picciani
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Maria Adele
authors.initials: MA
authors.lastname: Testi
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Militti
authors.affiliation: Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy.
authors.forename: Patrick
authors.initials: P
authors.lastname: Maisonneuve
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Valeri
authors.affiliation: Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian, 1, I-20133, Milan, Italy.
authors.forename: Angelica
authors.initials: A
authors.lastname: Sonzogni
authors.affiliation: Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Proto
authors.affiliation: Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Garassino
authors.affiliation: Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: De Braud
authors.affiliation: Division of Thoracic Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Ugo
authors.initials: U
authors.lastname: Pastorino
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058534:Class I Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors / Q000235:genetics; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D058534:Class I Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors; D019869:Phosphatidylinositol 3-Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; C484760:PIK3CA protein, human; C512478:EGFR protein, human
keywords: ALK; Branching; Dominant; EGFR; Gene; Intra-tumor heterogeneity; KRAS; Mutation; Next-generation sequencing; Private/private/hitchhiker