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
4079 - Triggering anti-GBM immune response with EGFR-mediated photoimmunotherapy
Presenter: Gabriela Kramer-marek
Session: Poster Display session 1
Resources:
Abstract
4364 - Upregulation of sFRP3 circulating expression levels correlates survival outcomes in glioblastoma
Presenter: Gema Bruixola
Session: Poster Display session 1
Resources:
Abstract
2327 - Characterization and pre-clinical modeling of genetic aberrations in pediatric gliomas
Presenter: Itai Moshe
Session: Poster Display session 1
Resources:
Abstract
3154 - Preclinical Study of Novel Tetracyclic Small Molecule, CC12, for Brain Cancer
Presenter: Liyun Fann
Session: Poster Display session 1
Resources:
Abstract
5759 - CHLOROBRAIN phase IB trial: The addition of chloroquine, an autophagy inhibitor, to concurrent radiation and temozolomide for newly diagnosed glioblastoma
Presenter: Inge Compter
Session: Poster Display session 1
Resources:
Abstract
1382 - A Phase II Clinical Trial Evaluating the Efficacy and Safety of Apatinib Combined with dose-dense Temozolomide in Recurrent Glioblastoma
Presenter: Yong Wang
Session: Poster Display session 1
Resources:
Abstract
4407 - Phase 0 Trial of Ceritinib in Brain Metastases and Recurrent Glioblastoma
Presenter: Shwetal Mehta
Session: Poster Display session 1
Resources:
Abstract
1469 - Pembrolizumab (Pem) in recurrent high-grade glioma (HGG) patients with mismatch repair deficiency (MMRd): an observational study
Presenter: Mario Caccese
Session: Poster Display session 1
Resources:
Abstract
4217 - Outcome of high-grade gliomas (HGGs) treated into immunotherapeutic early-phase clinical trials (ieCTs): a single-center experience
Presenter: Matteo Simonelli
Session: Poster Display session 1
Resources:
Abstract
5107 - Tolerability of PCV in Low Grade Glioma: a Real World Experience
Presenter: Razia Aslam
Session: Poster Display session 1
Resources:
Abstract