ALK and neoplasm: Despite of the tumor heterogeneity among SCLC and NSCLC tumors, drug resistance mechanisms have developed, reducing the efficacy of the current chemotherapeutics (e.g., etoposide, cisplatin, and carboplatin), radiotherapy (e.g., PCI) modalities, immunotherapeutics (e.g., atezolizumab and nivolumab), and targeted therapy (e.g., ALK and EGFR inhibitors) agents [229].