Gefitinib Treatment for Pulmonary Sarcomatoid Carcinoma Driven by an EGFR Mutation: Two Cases / 대한내과학회지

Sarcomatoid carcinoma of the lung is defined as a group of poorly differentiated non-small cell carcinomas that contain a component of sarcoma or a sarcoma-like element. Most sarcomatoid carcinomas are known to have a poor prognosis. We describe a 45-year-old female never smoker and 49-year-old female never smoker with sarcomatoid carcinomas of the lung that expressed a specific EGFR mutation: microdeletion of exon 19. Their cancers progressed rapidly, despite appropriate conventional chemotherapy. After they took the EGFR-targeted agent gefitinib, there was a dramatic reduction in tumor size. Sarcomatoid carcinoma of the lung is a rare cancer whose pathogenesis is not well understood. According to these cases, the EGFR mutation could be a driver mutation and the potential therapeutic target of EGFR-targeted agents for sarcomatoid carcinoma in lung cancer patients, especially never smokers.

Screening of Epidermal Growth Factor Receptor Gene Mutation in Non-Small Cell Lung Cancer Using a PCR-Based Enzymatic Digestion Method

PURPOSE: We applied a simplified method using polymerase chain reaction (PCR)-based enzymatic digestion for the detection of epidermal growth factor receptor (EGFR) mutation. MATERIALS AND METHODS: We selected 74 samples of adenocarcinoma of the lung with EGFR exons 19 and 21 that had been previously sequenced. We designed PCR primers and chose a DNA restriction enzyme. Seventy four additional lung cancer samples were tested as a test set. For test sets, the PCR-based method was performed first, followed by validation of the result by DNA sequencing. RESULTS: In the first sample group, we found 15 (20.3%) mutations in exon 19, and 9 (12.2%) mutations in exon 21 using the sequencing method. By using the PCR-based method, we were able to identify all of the mutated samples detected by the sequencing method. The PCR-based method also detected mutations in exon 19 in three additional samples and in exon 21 in one additional sample. In the second sample group, by performing the PCR-based method, we found 10 (13.5%) and 7 (9.5%) mutations in exons 19 and 21, respectively. Additional mutations in exon 19 were identified in 2 samples by the sequencing method. However, the sequencing method failed to identify a mutation in exon 21 in one sample. CONCLUSION: The sensitivity of the PCR-based enzymatic digestion method seems to be comparable to that of the traditional sequencing method for detecting EGFR mutations. Our method can be widely used as a screening test to select patients who may benefit from EGFR targeted therapy.

Molecular Diagnosis in Lung Cancer

The advent of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib and erlotinib has opened a new horizon for the therapeutic options for patients with advanced lung cancer. Treatment paradigms are shifting from cytotoxic chemotherapies to molecular-based targeted therapies. The discovery of somatic mutations in the exons 18 to 21 of the tyrosine kinase (TK) domain of EGFR has revolutionized the understanding of EGFR in lung carcinogenesis and this has opened a new era for the importance of predictive biomarkers to select the treatment of choice and for personalized therapy for lung cancer. Three important EGFR assays are used and these include mutational analysis, fluorescence in situ hybridization and immunohistochemistry. EGFR mutation study seems to be the most important biomarker to predict the response to EGFR-TKI, yet technical standardization for analyzing the status of EGFR mutation is the key factor. Therefore, it is important to standardize the approach and decide which assays are best to predict a patient's response to targeted therapies. It is also essential to determine the most cost-effective way to integrate EGFR molecular assays into clinical practice. This review will address the practical aspects of each of the currently proposed assays that have focused on EFGR mutational analysis and also the other important molecular markers such as k-ras mutation, the EML4-ALK fusion oncogene, ERCC1 and RRM1.