ABSTRACT
Targeted therapy for oncogenic genetic alterations has changed the treatment paradigm of advanced non-small cell lung cancer (NSCLC). Mutations in the BRAF gene are detected in approximately 4% of patients and result in hyper-activation of the MAPK pathway, leading to uncontrolled cellular proliferation. Inhibition of BRAF and its downstream effector MEK constitutes a therapeutic strategy for a subset of patients with NSCLC and is associated with clinical benefit. Unfortunately, the majority of patients will develop disease progression within 1 year. Preclinical and clinical evidence suggests that resistance mechanisms involve the restoration of MAPK signaling which becomes inhibition-independent due to upstream or downstream alterations, and the activation of bypass pathways, such as the PI3/AKT/mTOR pathway. Future research should be directed to deciphering the mechanisms of cancer cells' oncogenic dependence, understanding the tissue-specific mechanisms of BRAF-mutant tumors, and optimizing treatment strategies after progression on BRAF and MEK inhibition.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/pathology , Proto-Oncogene Proteins B-raf/genetics , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Lung Neoplasms/pathology , MAP Kinase Signaling System , Mutation , Mitogen-Activated Protein Kinase Kinases/metabolism , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic useABSTRACT
INTRODUCTION: Pulmonary blastoma is a rare malignancy, accounting for less than 0.5% of primary lung tumors. It belongs to the group of pulmonary sarcomatoid carcinomas, and it is typically characterized by a biphasic pattern of an epithelial and a mesenchymal component. Only a few hundred cases have been reported worldwide. The aim of this study is to review and critically assess the literature regarding pulmonary blastoma. MATERIAL AND METHODS: A narrative literature review of PubMed database from the inception of the database up to January 2021, limited to the English language, was conducted, using combinations of the following keywords: "pulmonary blastoma", "biphasic pulmonary blastoma", "sarcomatoid carcinoma". RESULTS: Pulmonary blastoma is composed of an epithelial and a mesenchymal malignant component. Regarding pathogenesis, the origin of the biphasic cell population remains elusive. Characteristic immunohistochemical stains are supportive of diagnosis.Clinically, the symptomatology is non-specific, while 40% of the cases are asymptomatic. It is diagnosed at a younger agecompared to other types of lung cancer, and it is often non-metastatic at diagnosis allowing for surgical treatment. Data on management and survival are scarce and mainly come from isolated cases. Advances on targeted therapy may provide novel treatment options. Given the rarity of the cases, multicenter collaboration is needed in order to establish therapeutic guidelines.
