Adenocarcinoma of the lung with rare insertion mutation in EGFR exon 19 that had partial response to gefitinib: a case report.

AIM: Classic activating mutations L858R and deletions in exon 19 (19del) in the gene for epidermal growth factor receptor (EGFR) are associated with sensitivity of the non-small cell lung cancer (NSCLC) to therapy with tyrosine kinase inhibitors (TKI). Insertions in EGFR exon 19 (19ins) are rare mutations in NSCLC; response of cases with 19ins to TKI is not well studied. Here we report a case of NSCLC with 19ins in a Russian patient who was treated with gefitinib. We also overview cases of 19ins reported in the literature.

CASE DESCRIPTION: A 48 years old female Russian patient was diagnosed with adenocarcinoma of the lung (T3N2M1, stage IV). Mutation 19ins was detected in the tumor biopsy by fragment analysis and genotyped by Sanger sequencing as p.I744_K745insKIPVAI. Treatment with gefitinib (250 mg/day) resulted in clinical and radiological improvements scored as partial response that lasted 12 months.

CONCLUSION: Treatment with gefitinib of lung adenocarcinoma that carries mutation EGFR 19ins can result in durable response.