NCOG-52. Single center retrospective analysis of adult patients with H3 altered gliomas

Abstract H3 altered gliomas represent a rare subtype of glioma most commonly seen in children but increasingly recognized in adults. Due to the rarity of these tumors, randomized controlled clinical trials have not been performed, and the ideal treatment regimen is unknown. Radiation therapy alone may not be inferior to radiation with chemotherapy. Patients diagnosed with an H3 altered glioma after the year January 1, 2017 were retrospectively identified. Sixteen patients with H3 K27-altered pathology were identified (8 female) with a median age of 30 years (R=17-42) and KPS at diagnosis of 80% (R=60-100). Five patients (3 female) with H3 G34-mutated pathology were identified with a median age of 18 years (R=17-31) and median KPS of 90% (90-100). Among the patients with H3 K27-altered gliomas, four underwent resection, eleven had biopsy alone, and one underwent laser interstitial therapy at initial diagnosis. All patients underwent radiation therapy, three without concomitant or adjuvant temozolomide. The remainder received temozolomide either concomitantly or adjuvantly along with other treatments such as Novo-TTF. All patients with H3 G34-mutated pathology underwent resection followed by focal radiation therapy with concomitant and adjuvant temozolomide, median of 12 adjuvant cycles (R=3-22). Two patients received at least one dose of CCNU with temozolomide, and one received an experimental vaccine. Patients with H3 K27-altered tumors had a median PFS and OS of 10 months and 24 months, respectively. Patients with H3 G34-mutated tumors had a median PFS and OS of 25 months and 37 months, respectively. At recurrence, 10/12 patients with H3 K27-altered glioma received salvage therapy with a median of 1 line of salvage therapy (R=1-4), while 3/4 patients with H3 G34 mutated glioma progressed and received a median of 2 lines of salvage therapy (R=1-2). Additional characteristics, molecular characterization and survival outcomes will be presented.