# EGFR exon 19 deletion & L858R

Source: https://onco.cc/terms/egfr-exon19-l858r/  
OnCo record `egfr-exon19-l858r` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Exon 19 deletion and L858R are the two common EGFR mutations, together ~85% of EGFR-mutant lung cancer, and both respond to EGFR pills.

## Summary

Exon 19 deletions and the L858R point mutation are the two common activating EGFR mutations in non-small-cell lung cancer, and together they account for most EGFR-mutant disease. Both are sensitising: first-line options include osimertinib, amivantamab with lazertinib, and osimertinib combined with chemotherapy, and the older drugs erlotinib and gefitinib were built around the same mutations. Exon 19 deletions tend to respond somewhat better to osimertinib than L858R does. Uncommon mutations such as G719X, L861Q and S768I respond to afatinib, while exon 20 insertions behave differently and need amivantamab or sunvozertinib. The term sits within the receptor tyrosine kinase activation pathway and is linked from the bottleneck on trials not representing the people who get cancer.

## Fields

- Kind: Term
- Last checked: 2026-09-06

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Epidermal_growth_factor_receptor
- FLAURA: osimertinib in untreated EGFR-mutated advanced non-small-cell lung cancer (NEJM 2018): https://doi.org/10.1056/NEJMoa1713137

## Connected records

- cancers: [EGFR-mutated non-small-cell lung cancer](https://onco.cc/cancers/egfr-mutant-nsclc/), [Lung cancer (all types)](https://onco.cc/cancers/lung-cancer/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/), [Resectable stage I to III non-small-cell lung cancer](https://onco.cc/cancers/resectable-nsclc/)
- targets: [EGFR](https://onco.cc/targets/egfr/)
- drugs: [Amivantamab](https://onco.cc/drugs/amivantamab/), [Erlotinib](https://onco.cc/drugs/erlotinib/), [Gefitinib](https://onco.cc/drugs/gefitinib/), [Lazertinib](https://onco.cc/drugs/lazertinib/), [Osimertinib](https://onco.cc/drugs/osimertinib/)
- trials: [ARCHER 1050](https://onco.cc/trials/nct01774721/), [FLAURA](https://onco.cc/trials/flaura/), [LUX-Lung 3](https://onco.cc/trials/lux-lung-3/)
- bottlenecks: [Trials do not represent the people who get cancer](https://onco.cc/bottlenecks/b-trial-diversity/)
- pathways: [Receptor tyrosine kinase activation](https://onco.cc/pathways/rtk-activation/)
- biomarkers: [EGFR exon 19 deletion](https://onco.cc/biomarkers/egfr-exon-19-deletion/), [EGFR L858R](https://onco.cc/biomarkers/egfr-l858r/)

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