Concurrent RB1 and TP53 Alterations Define a Subset of EGFR-Mutant Lung Cancers at risk for Histologic Transformation and Inferior Clinical Outcomes

J Thorac Oncol. 2019 Oct;14(10):1784-1793. doi: 10.1016/j.jtho.2019.06.002. Epub 2019 Jun 19.

Abstract

Introduction: EGFR-mutant lung cancers are clinically and genomically heterogeneous with concurrent RB transcriptional corepressor 1 (RB1)/tumor protein p53 (TP53) alterations identifying a subset at increased risk for small cell transformation. The genomic alterations that induce lineage plasticity are unknown.

Methods: Patients with EGFR/RB1/TP53-mutant lung cancers, identified by next-generation sequencing from 2014 to 2018, were compared to patients with untreated, metastatic EGFR-mutant lung cancers without both RB1 and TP53 alterations. Time to EGFR-tyrosine kinase inhibitor discontinuation, overall survival, SCLC transformation rate, and genomic alterations were evaluated.

Results: Patients with EGFR/RB1/TP53-mutant lung cancers represented 5% (43 of 863) of EGFR-mutant lung cancers but were uniquely at risk for transformation (7 of 39, 18%), with no transformations in EGFR-mutant lung cancers without baseline TP53 and RB1 alterations. Irrespective of transformation, patients with EGFR/TP53/RB1-mutant lung cancers had a shorter time to discontinuation than EGFR/TP53- and EGFR-mutant -only cancers (9.5 versus 12.3 versus 36.6 months, respectively, p = 2 × 10-9). The triple-mutant population had a higher incidence of whole-genome doubling compared to NSCLC and SCLC at large (80% versus 34%, p < 5 × 10-9 versus 51%, p < 0.002, respectively) and further enrichment in triple-mutant cancers with eventual small cell histology (seven of seven pre-transformed plus four of four baseline SCLC versus 23 of 32 never transformed, respectively, p = 0.05). Activation-induced cytidine deaminase/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like mutation signature was also enriched in triple-mutant lung cancers that transformed (false discovery rate = 0.03).

Conclusions: EGFR/TP53/RB1-mutant lung cancers are at unique risk of histologic transformation, with 25% presenting with de novo SCLC or eventual small cell transformation. Triple-mutant lung cancers are enriched in whole-genome doubling and Activation-induced cytidine deaminase/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like hypermutation which may represent early genomic determinants of lineage plasticity.

Keywords: EGFR-mutation; RB1; Small cell histologic transformation; TP53; Whole genome doubling.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenocarcinoma of Lung / drug therapy
  • Adenocarcinoma of Lung / genetics
  • Adenocarcinoma of Lung / mortality
  • Adenocarcinoma of Lung / pathology
  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / genetics
  • Cell Transformation, Neoplastic / drug effects
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / pathology*
  • ErbB Receptors / genetics
  • Female
  • Follow-Up Studies
  • Humans
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / mortality
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Mutation*
  • Prognosis
  • Protein Kinase Inhibitors
  • Retinoblastoma Binding Proteins / genetics*
  • Risk Factors
  • Small Cell Lung Carcinoma / drug therapy
  • Small Cell Lung Carcinoma / genetics
  • Small Cell Lung Carcinoma / mortality*
  • Small Cell Lung Carcinoma / pathology*
  • Survival Rate
  • Tumor Suppressor Protein p53 / genetics*
  • Ubiquitin-Protein Ligases / genetics*

Substances

  • Biomarkers, Tumor
  • Protein Kinase Inhibitors
  • RB1 protein, human
  • Retinoblastoma Binding Proteins
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • Ubiquitin-Protein Ligases
  • EGFR protein, human
  • ErbB Receptors