Second, the FLT signal is seen when the BLI signal greater than or equal to approximately 3 107 p/s/cm2/sr, providing a tumor-to-brain ratio of approximately 3. the ability to non-invasively assess tumor growth and response to therapy. ANOVA was conducted to evaluate for significant differences in the response. Results There was a survival benefit with ficlatuzumab alone or in combination with temozolamide. BLI was more sensitive than PET in detecting tumor cells. Fluoro-D-thymidine (FLT) PET provided a better signal-to-background ratio than 2[18F]fluoro-2-deoxy-D-glucose (FDG) PET. In addition, both BLI and FLT PET showed significant changes over time in the 1alpha, 24, 25-Trihydroxy VD2 control group as well as with response to therapy. MRI does not disclose any time-dependent change. Also, the MRI results showed a temporal delay in comparison to the BLI and FLT PET findings, showing similar results one drug cycle later. Conclusions Targeting the HGF/c-MET pathway with the novel agent ficlatuzumab appears promising for the treatment of glioblastoma. Various clinically applicable imaging modalities including FLT, PET, and MRI provide reliable ways of assessing tumor growth and response to therapy. Given the clinical applicability of these findings, future studies on patients with glioblastoma may be appropriate. Introduction Primary brain tumors are rare, with an incidence of 6.4 per 100,000 men and women per year in the United States, and a male-to-female ratio of 6:4 (1). Gliomas account for 30% to 40% of all intracranial tumors, of which approximately half are glioblastomas in adults, with a peak incidence between the ages of 40 and 65 years (2). Although gliomas are rare, they are medically important because of poor clinical outcomes. As such, there is considerable ongoing research on novel therapeutics for glioblastoma. One such agent is the anti-hepatocyte growth factor (HGF) antibody ficlatuzumab (AV-299; SCH 900105). Developed by Aveo Pharmaceuticals, it is a potent anti-HGF/c-MET antibody currently in phase II trials. The HGF/ c-MET pathway is thought to play an important role in regulating tumor growth, invasion, and metastasis. Deregulation of this pathway has been implicated in many tumors, including bladder, lung, breast, gastric, ovarian, prostate, colorectal, head and neck, certain sarcomas and several other solid tumors as well as hematologic malignancies. Ficlatuzumab has high affinity on the ligand HGF, thereby blocking the c-MET pathway. Initial clinical data of ficlatuzumab indicate a favorable tolerability profile, good combinability with other chemotherapeutic agents, and no dose-limiting toxicities noted (3, 4). Translational Relevance Human gliomas have a poor prognosis and therapeutic 1alpha, 24, 25-Trihydroxy VD2 options are limited. Ficlatuzumab is a novel therapeutic agent against the hepatocyte growth factor (HGF)/ c-MET pathway. Extensive preclinical work for ficlatuzumab using a mouse brain orthotopic model of glioblastoma is summarized here. This includes evaluation of dose response, comparison to the current standard of care, temozolomide, and ultimately noninvasive assessment of tumor response using a combination of bioluminescence imaging (BLI), small-animal positron emission tomography (PET), and small-animal MRI. Ficlatuzumab provides a survival benefit both alone and in conjunction with temozolomide. PET with fluoro-D-thymidine (FLT) provided a distinct advantage in this model over 2[18F]fluoro-2-deoxy-D-glucose (FDG). And, while not as sensitive as BLI, both FLT PET and MRI were able to assess response to therapy noninvasively. MRI may provide complimentary information to BLI and FLT PET. As such, combined (MRICPET fusion) imaging may have a role. On the basis of this prior work, the purpose of this experiment is to evaluate via molecular imaging the efficacy of ficlatuzumab in an orthotopic glioblastoma model in mice. Through a series of preclinical experiments, we evaluate the dose response of ficlatuzumab, efficacy of ficlatuzumab alone versus in conjunction with the standard-of-care chemotherapy temozolomide, and then assess tumor response using a combination of bioluminescence imaging (BLI), small-animal positron emission tomography (PET), and small-animal MRI. Materials and Methods Nonimaging studies on dose titration of ficlatuzumab and combination versus monotherapy with temozolomide Cell culture Human U87 malignant glioma (MG) cells were obtained from The American Type Culture Collection (ATCC; HTB-14) and maintained at low passage number. The cells were cultured in Dulbeccos Modified Eagles Medium (DMEM) supplemented with 10% FBS and maintained at 37C in an atmosphere containing 5% CO2 and 95% air. Cells for implantation were used within 5 subculture periods after thawing from liquid nitrogen stock. Only log-phase culture of cells at 70% to 80% confluency and more than 90% viability were used for implantation. On the day of surgery, U87 MG cells were collected by trypsinization and resuspended in PBS to obtain 3 105 cells in Mouse monoclonal to ABCG2 2 L for injection purposes. U87 cells secrete about 10 to 15 ng/mL of HGF in the culture medium after 24 to 48 hours of culture. They express relatively low levels of c-Met as detected by fluorescence-activated cells sorting (FACS) analysis and Western blotting. 1alpha, 24, 25-Trihydroxy VD2 Tumor implantation and experimental design A total of.