The effect of treatment on relative tumor volume is presented in Figure 2 em B /em . Open in a separate window Figure 2 (A) Fluorescence images of representative green fluorescent protein (GFP)-expressing NSCLC growing in the brain of nude mice from each treatment group at each time point after the onset of Oxytocin treatment. Non-small cell lung malignancy (NSCLC), which accounts for approximately 85% of all lung cancers, is one of the most frequent cancers to metastasize to brain , , . It is estimated that about 30% to 50% of patients with metastatic NSCLC will develop brain metastasis , . Clinical studies have exhibited that survival time is significantly reduced after the occurrence of brain metastases in NSCLC patients . The current treatment options for NSCLC with brain metastases include medical procedures, radiotherapy and chemotherapy. The efficacy of standard systemic chemotherapy Oxytocin of brain metastases of NSCLC patients is limited due in large part to the bloodCbrain barrier (BBB) , , . Higher incidences of brain metastases for patients with epidermal growth factor receptor Oxytocin (EGFR)-mutant metastatic NSCLC were found compared to EGFR wild type , . Several generations of EGFR tyrosine kinase inhibitors (TKIs) have been found to be highly effective compared to chemotherapy for NSCLC patients with brain metastases , , , . Recent pre-clinical and clinical studies suggest that some third-generation inhibitors can cross the BBB and show anti-tumor activity , , , . Osimertinib (AZD9291), a third-generation inhibitor of mutant EGFR, has been approved by the United States Food and Drug Rabbit Polyclonal to ARRB1 Administration (FDA) for EGFR T790 MCpositive NSCLC , . Osimertinib was highly active in patients with lung malignancy with the EGFR T790 M mutation , , , , , and is more efficacious compared to standard first collection therapies , , , . Osimertinib showed higher concentrations in mouse brain tissue compared to plasma . Osimertinib has improved BBB penetration ability and has potential for NSCLC patients with brain metastasis , , . Koba et al.  reported that NSCLC patients made up of an EGFR T790 M mutation with multiple brain metastases showed a strong response to osimertinib within 2 weeks without radiation therapy. Further, Xie et al. , in a retrospective study, showed that osimertinib is effective for patients with progressing brain metastases and that radiation therapy is not needed before osimertinib treatment. Osimertinib showed high efficacy in a leptomeningeal carcinomatosis (LMC) model with EGFR-mutant lung malignancy , against lung malignancy with multiple HER2 aberrations , induced apoptosis in oral epidermoid and colorectal malignancy cells , , and showed good efficacy against breast malignancy with L755P and L755S mutations . In the present study, we established an imageable orthotopic xenograft mouse model of PC-9 expressing green fluorescence protein (PC-9-GFP) growing in the brain and decided the efficacy of osimertinib compared with conventional chemotherapy. Materials and Methods Cell lines and Cell Oxytocin Culture The PC-9-GFP human EGFR-mutant NSCLC cell collection with stable high-expression of GFP (AntiCancer, Inc., San Diego, CA) was managed in RPMI-1640 (Mediatech, Inc. Manassas, VA) with 10% fetal bovine serum. All media were supplemented with penicillin and streptomycin. Cells were cultured at 37 C with 95% air flow and 5% CO2. Mice Athymic nu/nu nude mice (AntiCancer Inc., San Diego, CA), 6C7 weeks aged, were used in this study. The animals were fed an autoclaved laboratory rodent diet. All animal studies were conducted in accordance with the principles and procedures layed out in the National Institute of Health Guideline for the Care and Use of Animals under Assurance Number A3873C1. Animals were anesthetized by subcutaneous injection of a ketamine combination (0.02 ml solution of 20 mg/kg ketamine, 15.2 mg/kg xylazine, and 0.48 mg/kg acepromazine maleate). The animals were observed on a daily basis and humanely sacrificed by CO2 inhalation if they met the following humane endpoint criteria: severe tumor burden (more than 20 mm in diameter), prostration, significant body weight loss, difficulty breathing, rotational motion and body temperature drop. Subcutaneous Tumor Growth PC-9-GFP cells growing in culture were harvested by trypzinization and washed two times with phosphate-buffered saline (PBS, Mediatech, Inc. Manassas, VA). Cells (2??106) were injected subcutaneously into the right flank of mice in a total volume of 100 l PBS. The subcutaneous tumors were used as the source of tissue for orthotopic implantation into the brain. Surgical Orthotopic Implantation (SOI) for Establishment of Brain Implantation Model Tumor pieces (1 mm3) derived from PC-9-GFP subcutaneous tumors growing in the nude mouse were implanted by surgical orthotopic implantation (SOI) onto the left intracranial space of mice. Briefly, a small incision (0.4C0.5 cm) on the top of the head was made and osteotomy was performed with a sharp pointed scalpel to make a flap. A single.