HGG-39. CLINICAL CHARACTERISTICS AND SURVIVAL OUTCOMES OF DIFFUSE HEMISPHERIC GLIOMA, H3 G34-MUTANT: INTERIM RESULTS OF A MULTICENTRE INTERNATIONAL STUDY
Cameron Crowell, Julie Bennett, Pratiti Bandopadhayay, Dominik Sturm, Adam L Green, Mary MacNeil, Magimairajan Issai Vanan, Valérie Larouche, Samuele Renzi, Brandon Imber, Jacquelyn Jones, Sébastien Perreault, Daddy Mata-Mbemba, Charlotte Feddersen, Olivia Vizzini, Michal Zápotocký, Sylvia Cheng, Rebecca Harrison, Aimee Popovacki, Darren Klawinski, Jordan R Hansford, Sarah Lapointe, Romain Cayrol, Nikhil Mankuzhy, Christina Coleman, Mariah Wright-Nadkarni, Ralph Salloum, Matthias Karajannis, Cynthia Hawkins, David T W Jones, Keith L Ligon, Nada Jabado, Craig ErkerAbstract
BACKGROUND
Diffuse hemispheric glioma, H3 G34-mutant (G34-DHG) is generally associated with very poor outcome. Little is known, however, regarding long-term survivors and associated prognostic factors.
METHODS
This retrospective, multicentre study was designed to investigate clinical, molecular, and imaging variables that may impact the survival of patients with G34-DHG. Patients of any age diagnosed with G34-DHG after January 1, 1995, with at least one measure of survival or progression were eligible.
RESULTS
69 patients with G34-DHG (62 G34R, 5 G34V, 2 diagnosed by methylation profiling only) have been included to date. Median age at diagnosis was 16.0 years (range: 2–38). 75% of patients were under the age of 18. 52% of patients were male. 8% of patients had multifocal/disseminated disease at diagnosis. Upfront therapy included gross/near total resection in 47% of patients, radiation therapy in 88% (89% focal, 6% CSI), and maintenance chemotherapy in 85% (62% TMZ-based, 33% TMZ/CCNU, 5% non-TMZ). Median follow-up time was 20.0 months (IQR=12.0–30.0). 86% of patients had progressive disease with a median time-to-progression of 14.0 months (IQR=6.6-22.5). At last follow-up, 70% of patients had died from disease, 23% were alive with disease, and 7% were alive without disease. Median overall survival was 24.7 months (IQR=18.8–30.6). Median time from progression to death was 6.0 months (IQR=2.0–10.8). Six patients were found to be long-term survivors > 5 years (four dead of disease, one alive with disease, one alive without disease). Log-rank assessment revealed improved survival to be associated with upfront gross/near-total resection (p=0.002) and age at diagnosis ≥ 18 years (p=0.012).
CONCLUSIONS
Surprisingly, we found that nearly 10% of G34-DHG patients survive 5 years or longer. Radical surgical resection and older age at diagnosis appear to be associated with longer survival. Imaging and molecular prognostic factors are being further investigated.