Abstract 5739
Background
Mutation of either the intracellular catalytic domain or the extracellular domain of the receptor for epidermal growth factor (EGFR) drives oncogenicity. Extracellular domain EGFR mutations are highly expressed in patients with glioblastoma. Despite clinical success with targeting EGFR catalytic site mutants, no drugs have proven effective in glioblastoma patients expressing extracellular EGFR mutations.
Methods
Herein, we define the molecular mechanism for oncogenic activation of families of extracellular EGFR mutations and reveal how this mechanism renders current generation small molecule ATP-site inhibitors ineffective. We define these types of lesions as allosteric oncogenic mutations.
Results
We demonstrate that a group of the most commonly expressed extracellular domain EGFR mutants expressed in glioblastomas is activated by disulfide-bond mediated covalent homodimerization, collectively referred to as locked dimerization (LoDi-EGFR oncogenes). Strikingly, current generation small molecules binding to the active kinase conformation potently inhibit catalytic site mutants, but induce covalent dimerization and activate LoDi-EGFR receptors, manifesting in paradoxical acceleration of proliferation. Herein we describe the discovery of novel ATP competitive small molecules that potently (<50nM) inhibit the family of LoDi-EGFR oncogenes expressed in GBM, and importantly, achieve selectivity versus WT-EGFR of greater than 10-fold.
Conclusions
These data demonstrate how the locked-dimer mechanism of EGFR oncogenesis has profound impact on the activity of small molecules acting at the distal catalytic site, providing further evidence for “inside-out” allosteric signaling in EGFR. This provides a mechanistic understanding for the failure of current generation EGFR inhibitors to effectively treat LoDi-EGFR mutants in GBM and sets guidelines for the discovery and development of novel selective LoDi-EGFR inhibitors.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Black Diamond Therapeutics.
Funding
Black Diamond Therapeutics.
Disclosure
E. Buck: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: Black Diamond Therapeutics. M. O’Connor: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: Black Diamond Therapeutics. A. Flohr: Leadership role, Shareholder / Stockholder / Stock options: Black Diamond Therapeutics. R. Iacone: Leadership role, Shareholder / Stockholder / Stock options: Black Diamond Therapeutics. A.V. Mayweg: Leadership role, Shareholder / Stockholder / Stock options, Officer / Board of Directors: Black Diamond Therapeutics. D.M. Epstein: Leadership role, Shareholder / Stockholder / Stock options, Officer / Board of Directors: Black Diamond Therapeutics. All other authors have declared no conflicts of interest.
Resources from the same session
3887 - First Real Life Data on Durvalumab after definitive concomitant ChemoRadiotherapy (cCRT) in unresectable Stage (St) III Non-Small Cell Lung Cancer (NSCLC) in France: Analysis of 591 patients (pts) enrolled in the French cohort (c) Temporary Authorization of Use (ATU)
Presenter: Virginie Avrillon
Session: Poster Display session 1
Resources:
Abstract
682 - EGFR Inhibitor Versus Chemotherapy as Adjuvant Treatment for Locally-advanced EGFR-mutant Non-Small Cell Lung Cancer
Presenter: Peng Xie
Session: Poster Display session 1
Resources:
Abstract
2509 - Afatinib in EGFR TKI-naïve patients with EGFR mutation-positive (EGFRm+) NSCLC: interim analysis of a Phase IIIb, multi-national, open-label study
Presenter: Filippo de Marinis
Session: Poster Display session 1
Resources:
Abstract
3300 - First-line ceritinib versus chemotherapy in patients (pts) with advanced ALK rearranged (ALK+) non-small cell lung cancer (NSCLC): ASCEND-4 Asian subgroup analysis
Presenter: Daniel SW Tan
Session: Poster Display session 1
Resources:
Abstract
2653 - A combined analysis of two Phase IIIb studies of afatinib in EGFR TKI-naïve patients (pts) with EGFR mutation-positive (EGFRm+) NSCLC
Presenter: Filippo de Marinis
Session: Poster Display session 1
Resources:
Abstract
3663 - Impact of plasma EGFR mutation fractions on response to first generation tyrosine-kinase inhibitor in treatment of naïve non-small cell lung cancer patients
Presenter: Xiaohong Wang
Session: Poster Display session 1
Resources:
Abstract
5921 - Definition of an afatinib trough concentration threshold in the treatment of NSCLC
Presenter: Stephane Bouchet
Session: Poster Display session 1
Resources:
Abstract
2852 - A Phase Ib Trial of Neoadjuvant Chemoradiotherapy and Durvalumab(MEDI4736) for Potentially Resectable stage III Non-Small Cell Lung Cancer (NSCLC)
Presenter: Beung chul AHN
Session: Poster Display session 1
Resources:
Abstract
3273 - Low expression of Notch1 and combined Notch1/HES1 are associated with adverse survival factor for limited stage small cell lung cancer
Presenter: Jinsoo Lee
Session: Poster Display session 1
Resources:
Abstract
5141 - Mutational profiling of tumor tissue and sequential plasma illustrates emergent clones during treatment in late stage small cell lung cancer (SCLC)
Presenter: Stephanie Yaung
Session: Poster Display session 1
Resources:
Abstract