Heterogeneity of epidermal growth factor receptor mutations in lung adenocarcinoma harboring anaplastic lymphoma kinase rearrangements: A case report

Conversion from Positive to Negative EGFR Mutation due to Clonal Selection during Long-Term Treatment with Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors: A Case Report

A 77-year-old woman with postoperative recurrent non-small cell lung adenocarcinoma, which exhibited an epidermal growth factor receptor (EGFR) L858R mutation, was treated with gefitinib and erlotinib. Seven years after the start of treatment, the patient experienced a recurrence of malignant pleural effusion. However, 3 different genetic tests revealed that the lung adenocarcinoma cells in the pleural effusion had lost EGFR L858R mutation, suggesting that long-term treatment with EGFR-tyrosine kinase inhibitors (TKIs) converted EGFR mutation from positive to negative. The negative conversion of EGFR mutation as a mechanism of acquired resistance to EGFR-TKIs is considered rare and needs to be further investigated.

A heterochronic genetic change from an EGFR mutation to an ALK rearrangement in a patient with lung adenocarcinoma: a case report

An 87-year-old man with postoperative recurrent lung adenocarcinoma was treated with gefitinib. At the beginning of treatment, surgically resected archived tumor tissue revealed a deletion in exon 19 of the EGFR gene, but no ALK gene rearrangement. After gefitinib treatment for 9 months, the disease progressed. Bronchoscopic rebiopsy was used to evaluate resistance mechanisms, and revealed lung adenocarcinoma with wild-type EGFR genes and a newly emerged ALK gene rearrangement. Treatment was switched to alectinib and a partial response was achieved within 4 weeks. This is a rare case of heterochronic genetic change to an ALK gene rearrangement in EGFR mutant lung adenocarcinoma.