Survival outcomes associated with first-line PCV or temozolomide in combination with radiotherapy in IDH-mutant 1p/19q-codeleted grade 3 oligodendroglioma

2004 Background: Patients with IDH-mutant 1p/19q-codeleted grade 3 oligodendroglioma (O3 IDHmt/Codel ) benefit from adding alkylating chemotherapy to radiotherapy (RT). However, the optimal chemotherapy regimen between Procarbazine, CCNU, and Vincristine (PCV) and Temozolomide (TMZ) remains unclear given the lack of randomized trial data comparing both regimens. Methods: The objective was to assess the overall (OS) and progression-free (PFS) survival associated with first-line PCV/RT versus TMZ/RT in patients diagnosed with O3 IDHmt/Codel . We included patients with histologically-proven O3 IDHmt/Codel (according to WHO criteria) from the French national prospective cohort study POLA. All tumours underwent central pathological review. OS and PFS from surgery were estimated using Kaplan-Meier method and Cox regression model. Results: 305 newly-diagnosed O3 IDHmt/Codel patients treated with RT and chemotherapy between 2008 and 2022 were included. 67.9% of patients (n=207) were treated with PCV/RT and 32.1% with TMZ/RT (n=98). Median follow-up was 78.4 months (IQR=44.3-102.7). Median OS was not reached (95%CI: NR-NR) and 140 months (95%CI: 110-NR) in the PCV/RT and TMZ/RT groups, respectively (log-rank P