title: Decreased tumor apparent diffusion coefficient correlates with objective response of pediatric low-grade glioma to bevacizumab.
abstract: Recent small, retrospective series suggest bevacizumab may be a therapeutic option for recurrent pediatric low-grade glioma (LGG). Assessment of therapeutic responses is complicated by the unpredictable natural history of these tumors. Because diffusion-weighted imaging quantifies microscopic water motion affected by cellular density and histologic features, we hypothesized that it may be helpful in monitoring therapeutic response of LGG to bevacizumab. We retrospectively reviewed eight consecutive patients, median age 4.8 (range 2.3-12.3) years at initiation of bevacizumab therapy for recurrent or refractory LGG. Patients received 10 mg/kg/dose every 2 weeks (median 16 doses/therapy course). Mean apparent diffusion coefficient (ADC) was measured and analyzed in respect to tumor volume. Following the first treatment course, seven of eight patients had reduced tumor volume (≥25 %) and ADC. The median decrease in tumor volume was 47% (range -6 to 78 %) and the median decrease in ADC was 14 % (range -5 to 30 %). The ADC was significantly decreased during therapy, whereas the decrease in volume was seen only after therapy completion. There was a positive correlation between percent change in tumor volume and ADC (p < 0.05). We report a decrease in tumor ADC during initial bevacizumab therapy that is accompanied by a decrease in volume following therapy. Imaging changes in microscopic water motion associated with histology may be useful in monitoring the therapeutic response of LGG to bevacizumab.
authors.affiliation: Department of Oncology, Lucile Packard Children's Hospital, Stanford University, 750 Welch Rd Suite 317, Palo Alto, CA, 94304, USA.
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Hsu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Lober
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Li
authors.forename: Sonia
authors.initials: S
authors.lastname: Partap
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Murphy
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Barnes
authors.forename: Paul G
authors.initials: PG
authors.lastname: Fisher
authors.forename: Kristen W
authors.initials: KW
authors.lastname: Yeom
mesh_terms: D000293:Adolescent; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000068258:Bevacizumab / Q000627:therapeutic use*; D001921:Brain / Q000187:drug effects / Q000473:pathology; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D012189:Retrospective Studies
chemical_list: D020533:Angiogenesis Inhibitors; D000068258:Bevacizumab