Characterization of epidermal growth factor receptor (EGFR) P848L, an unusual EGFR variant present in lung cancer patients, in a murine Ba/F3 model

Abstract

Lung cancer patients with mutations in epidermal growth factor receptor (EGFR) benefit from treatments targeting tyrosine kinase inhibitors (TKIs). However, both intrinsic and acquired resistance of tumors to TKIs are common, and EGFR variants have been identified that are resistant to multiple TKIs. In the present study, we characterized selected EGFR variants previously observed in lung cancer patients and expressed in a murine bone marrow pro‐B Ba/F3 cell model. Among these EGFR variants, we report that an exon 20 deletion/insertion mutation S768insVGH is resistant to erlotinib (a first‐generation TKI), but sensitive to osimertinib (a third‐generation TKI). We also characterized a rare exon 21 germline variant, EGFR P848L, which transformed Ba/F3 cells and conferred resistance to multiple EGFR‐targeting TKIs. Our analysis revealed that P848L (a) does not bind erlotinib; (b) is turned over less rapidly than L858R (a common tumor‐derived EGFR mutation); (c) is not autophosphorylated at Tyr 1045 [the major docking site for Cbl proto‐oncogene (c‐Cbl) binding]; and (d) does not bind c‐Cbl. Using viability assays including 300 clinically relevant targeted compounds, we observed that Ba/F3 cells transduced with EGFR P848L, S768insVGH, or L858R have very different drug‐sensitivity profiles. In particular, EGFR P848L, but not L858R or S768insVGH, was sensitive to multiple Janus kinase 1/2 inhibitors. In contrast, cells driven by L858R, but not by P848L, were sensitive to multikinase MAPK/extracellular‐signal‐regulated kinase (ERK) kinase and ERK inhibitors including EGFR‐specific TKIs. These observations suggest that continued investigation of rare TKI‐resistant EGFR variants is warranted to identify optimal treatments for cancer.

A Mutational Survey of Acral Nevi

“…In all cases, BRAF and NRAS driver mutations were mutually exclusive. Other key findings included a noncanonical mutation in EGFR (p.P848L; allelic frequency: 42%), which is known to be pathogenic, that overlapped with a BRAF V600E mutation …”

“…12 Genetic variants were identified with GATK UnifiedGenotyper (Broad Institute) simultaneously on all tumor samples (n = 50) and a subset of available normal samples (n = 4). Somatic mutations were enriched according to previously described methods 13 by excluding variants seen in 1000 genomes at greater than 1% or seen in more than 1 normal sample from this study. Given the lower pathologic tumor cellularity of most samples (median [range], 25% [5%-80%]), mutations with allelic frequency greater than 40% were filtered out as likely inherited variants.…”

A Genomically and Clinically Annotated Patient Derived Xenograft (PDX) Resource for Preclinical Research in Non-Small Cell Lung Cancer

“…J000100672 harbors the exon 20 insertion associated with de novo resistance to TKI inhibitors (54). TM00253 harbors the mutation EGFR V834L, which is associated with decreased response to erlotinib (55). Cohorts of tumor-bearing mice of these models, except for TM00193, were treated with single-agent erlotinib.…”

Germline EGFR mutations in lung cancer (Review)

“…These findings provide greater insight into the response of patients with lung cancer and rare EGFR mutations, such as the P848L mutation, to gefitinib, regardless of whether the mutation is somatic or germline. Sarcar et al (33) studied patients with the EGFR germline mutation and established P848L-transformed Ba/F3 cells that were resistant to multiple EGFR-TKIs but sensitive to a number of Janus kinase 1/2 inhibitors (Table IV). --------------------------------------------------------------- NA, information not available; M, male; F, female; TKI, tyrosine kinase inhibitor; AD, adenocarcinoma; BAC, bronchioloalveolar carcinoma; AAH, atypical adenomatous hyperplasia.…”