Abstract B23: Novel epidermal growth factor receptor inhibitors cross the blood-brain barrier and inhibit the growth of metastatic non-small cell lung cancer

Deaths from solid tumors are often not due to the primary lesion but to metastatic disease at distal sites such as the lung, liver, and brain. Patients with non-small cell lung cancer (NSCLC) experience brain metastases, a poor prognostic marker, at an incidence rate of 30-50%. A significant proportion of the metastatic tumors express activating mutations of the EGFR, including exon 19 deletions as well as point mutations within the enzyme active site (L858R), which confer increased sensitivity to EGFR inhibitors. However, current small-molecule therapeutics poorly inhibit the growth of NSCLC brain metastases due to difficulty crossing the blood-brain barrier and harmful off-target effects. Thus, NSCLC patients with brain metastases have access to very few emerging treatment options. We have synthesized a novel class of compounds that irreversibly inhibit the epidermal growth factor receptor (EGFR) in the nanomolar range in vitro, and demonstrate a high degree of selectivity for EGFR mutants found frequently in NSCLC, in particular exon 19 deletions and L858R mutations, while sparing wild-type (WT) EGFR. Two compounds, LL-001 and LL-019, from Capella Therapeutics, Inc., inhibited L858R EGFR-mediated autophosphorylation and phosphorylation of downstream targets Akt and ERK MAP kinase at a concentration of approximately 100nM and blocked the kinase activity of an EGFR mutant, T790M, which confers resistance to first-generation EGFR inhibitors. In contrast, these compounds only weakly inhibited WT EGFR and failed to inhibit either the insulin receptor or insulin-like receptor-I, suggesting that these inhibitors would produce minimal off-target side effects in treated patients. Both compounds induced full remission of subcutaneous tumors with the human NSCLC cell line H1975 (T790M/L858R+). Most notably, pharmacokinetic studies showed that these compounds, when administered at a concentration of 150mg/kg in mice, showed no signs of toxicity and were found in the brain at concentrations ranging from 12-171 times higher than the GI50 for inhibition of EGFR+ NSCLC cell line proliferation in vitro. To determine whether these compounds could treat NSCLC brain metastases, we developed intracranial and intracardiac injection orthotopic xenograft models of brain metastatic NSCLC. LL-001 and LL-019 could induce remission of brain tumors in mice injected intracranially with the human NSCLC cell line HCC827-luciferase, which expresses an exon 19 deletion mutant of EGFR. Likewise, both compounds inhibited the growth of the human NSCLC cell line PC9M in an intracardiac model of brain metastatic NSCLC, and greatly extended the survival of mice compared to those receiving vehicle alone. Our results indicate that LL-001 and LL-019 can cross the blood-brain barrier at levels sufficient to inhibit the growth of brain metastatic lung cancer, with minimal deleterious off-target effects. These compounds show promise for the treatment of critically underserved NSCLC patients with brain metastases. Citation Format: Michelle Muldong, Christina Jamieson, Yun Oliver Long, Ida Deichaite, David W. Anderson, Alan Lewis, Nicholas A. Cacalano. Novel epidermal growth factor receptor inhibitors cross the blood-brain barrier and inhibit the growth of metastatic non-small cell lung cancer [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr B23.