EPID-23. Patterns of care and clinical outcomes of patients with <i>IDH</i> -mutant high-grade glioma in the United States from 2014-2023: a real-world analysis of the Tempus Lens database

Abstract Molecular characterization of gliomas has reshaped the classification and provided more accurate prognosis for IDH-mutant gliomas. However, patterns of care and outcomes after recurrence have not been well characterized. To support future clinical trial design for recurrent IDH-mutant high grade glioma (IDHmHGG), this study explored demographics, treatment patterns, and outcomes in this population. Among 3694 patients with WHO grade 3-4 HGG in the Tempus Lens database, patients who met these criteria were selected: 1. being diagnosed between 2014-2023, 2. Being positive for IDH mutation, and 3. received first-line standard-of-care (radiotherapy plus temozolomide or PCV) with documented subsequent therapies. 237 patients met these criteria. At diagnosis: median age = 36 years (IQR 31-46), male 143 (60%). Most patients had astrocytoma [100 (42%) grade 3, 86 (36%) grade 4], while 51 (22%) had grade 3 oligodendroglioma. 182 (77%) patients were treated at academic medical centers. First-line therapy consisted of radiotherapy plus temozolomide for all astrocytomas and most oligodendrogliomas (45 of 51; 6 received PCV). With median follow-up of 33 months, 37 grade 4, and 29 grade 3 astrocytoma patients and 14 grade 3 oligodendroglioma patients had recurrent disease. Median time to first recurrence was 17.0 months (95% CI 14.7-35.2) for grade 4 and 43.9 months (34.4-58.0) for grade 3 astrocytomas, and 49.3 months (34.6-not reached) for grade 3 oligodendroglioma. The most common treatment options administered at recurrence for astrocytoma were: re-treatment with temozolomide (13, 20%), bevacizumab (9, 14%), with lomustine, re-irradiation therapy, clinical trial and IDH inhibitors as additional less common alternatives. At recurrence, oligodendrogliomas were most frequently treated with bevacizumab (5, 36%), procarbazine and lomustine (3, 21%), or PCV (2, 14%). Additional findings, including molecular heterogeneity and survival data will be presented at the meeting. IDHmHGG represents a heterogeneous group of tumors with no clear standard-of-care upon recurrence after initial treatment.