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Case Reports
. 2018 Dec 1;57(23):3429-3432.
doi: 10.2169/internalmedicine.0999-18. Epub 2018 Aug 10.

An EGFR-mutated Lung Adenocarcinoma Undergoing Squamous Cell Carcinoma Transformation Exhibited a Durable Response to Afatinib

Free PMC article
Case Reports

An EGFR-mutated Lung Adenocarcinoma Undergoing Squamous Cell Carcinoma Transformation Exhibited a Durable Response to Afatinib

Mitsuo Sato et al. Intern Med. .
Free PMC article


Squamous cell carcinoma (SCC) transformation has been identified as a mechanism of resistance to first-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), gefitinib or erlotinib, in EGFR-mutated lung cancer. However, whether second- or third-generation TKIs can overcome resistance due to SCC transformation remains unclear. We herein report an EGFR-mutated lung adenocarcinoma undergoing transformation into SCC that exhibited a durable response to afatinib, which is a second-generation irreversible EGFR-TKI. We suggest that afatinib can be considered as a treatment option for EGFR-mutated tumor undergoing SCC transformation, particularly in the absence of a T790M mutation.

Keywords: EGFR mutation; afatinib; erlotinib; squamous cell carcinoma transformation.


(A) The clinical course of the present case shown by images of serial computed tomography and the treatment regimens administered. A rebiopsy with a core needle was performed from a metastatic lesion at the right latissimus dorsi muscle (white arrow). (B) The histopathological results demonstrate transformation from adenocarcinoma to squamous cell carcinoma (SCC). Cell blocks before treatment initiation showing adenocarcinoma, as characterized by malignant epithelial cells immunohistochemically positive for thyroid transcription factor-1 (TTF1) and negative for p40. A core needle biopsy after erlotinib and other treatment regimens showing an SCC, as characterized by keratin pearl formation (Hematoxylin and Eosin staining) as well as an immunohistochemical staining pattern indicative of SCC (p40-positive and TTF-1-almost-negative). CBDCA: carboplatin, PEM: pemetrexed, DTX: docetaxel, RT: radiation therapy

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