EGFR exon 19 deletion is the most common actionable EGFR-sensitizing mutation in NSCLC ad...

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

ID	`RF-NSCLC-EGFR-EX19DEL-ACTIONABLE`
Type	Red flag
Status	reviewed 2026-04-27 \| pending_clinical_signoff
Diseases	`DIS-NSCLC`
Sources	`SRC-ESMO-NSCLC-METASTATIC-2024` `SRC-FLAURA-SORIA-2018` `SRC-MARIPOSA2-PASSARO-2024` `SRC-NCCN-NSCLC-2025`

Red Flag Origin

Definition	EGFR exon 19 deletion is the most common actionable EGFR-sensitizing mutation in NSCLC adenocarcinoma (~45-50% of EGFR-mutant cases). FDA/EMA-approved 1L targeted therapy is osimertinib (FLAURA — mPFS 18.9 vs 10.2 mo, OS 38.6 vs 31.8 mo); MARIPOSA-2 establishes 2L amivantamab + lazertinib + chemo post-osimertinib progression.
Clinical direction	intensify
Category	high-risk-biology
Shifts algorithm	ALGO-NSCLC-METASTATIC-1L, ALGO-NSCLC-METASTATIC-2L

Trigger Logic

{
  "any_of": [
    {
      "finding": "egfr_exon19_deletion",
      "value": true
    },
    {
      "finding": "egfr_ex19del",
      "value": "positive"
    },
    {
      "finding": "egfr_mutation",
      "value": "exon19_deletion"
    }
  ],
  "type": "biomarker"
}

Notes

Routes 1L → osimertinib 80 mg PO daily (FLAURA). Acquired-resistance surveillance: ctDNA at progression for T790M (rare on osimertinib), C797S (~20% of post-osimertinib resistance), MET amplification, histologic transformation. 2L: MARIPOSA-2 amivantamab + lazertinib ± chemo. Stage I-IIIA resected — adjuvant osimertinib (ADAURA). Access UA: osimertinib not consistently NSZU-reimbursed; major barrier; consider patient-assistance programs.

Used By

Algorithms

ALGO-NSCLC-ADJUVANT - ALGO-NSCLC-ADJUVANT
ALGO-NSCLC-METASTATIC-1L - ALGO-NSCLC-METASTATIC-1L
ALGO-NSCLC-METASTATIC-2L - ALGO-NSCLC-METASTATIC-2L
ALGO-NSCLC-RESECTABLE-PERIOP - ALGO-NSCLC-RESECTABLE-PERIOP