ID #643 Survival outcomes in more than 1000 patients with diffuse intrinsic pontine glioma over three decades from the international diffuse intrinsic pontine glioma registry

Abstract Background DIPG is a fatal cancer. Radiation is the only treatment that unambiguously prolongs survival. Recent non-randomized studies have reported improved survival in select patients when compared to historical controls. This stimulated a need to revise historical estimates of overall survival for the current era of trials. Methods We retrospectively analyzed patients enrolled in the International DIPG Registry between 1990-2024 to investigate overall survival and its predictors, focusing on the impact, if any, of the changing treatment landscape. Results Central review confirmed n = 1200/1261 screened patients with DIPG. Patients were diagnosed over 34 years (1990-1999: 3%, 2000-2009: 36%, 2010-2009: 54%, 2020-2024: 7%). Median age 6.5 years (IQR: 4.8, 9.7), male: female 0.8, 29% with atypical radiology, 36% with tissue diagnosis (biopsy: 24%; rest: autopsies), with 83% of tumors sequenced confirmed to harbor H3K27M. Median PFS 8.4 months (95%CI: 7.7, 9.0). Median OS was 10.8 months (95%CI: 10.4, 11.1). Those who did not receive radiation had dismal OS of 3.6 months (95% CI: 2.5, 4.6; p 0.001). OS for age ≥10 years (median: 12.7 months) and ≤3 years (median: 13.2 months) was superior to others (median: 10.5 months; p 0.001). Intriguingly, patients receiving additional chemotherapy had superior OS (12.2 vs 7.2 months; p 0.001). At progression, patients receiving re-irradiation had superior survival (median OS: 16.5 months; p 0.001) compared to those receiving no active agents (9.8 months), chemotherapy (13 months) or novel therapeutics (12 months). The latter included demethylating agents, targeted small molecules and monoclonal antibodies. On multivariate analysis, re-radiation remained the only significant predictor of survival (p = 0.009), while age, sex, atypical radiology, H3K27M status, decade of diagnosis, chemotherapy and trial enrolment did not affect OS. Conclusions Our study underscores the urgent need for novel effective therapies in DIPG and provides updated survival data to serve as historical control for future trials