INNV-31. PROTECT: PROCARBAZINE, LOMUSTINE, AND VINCRISTINE VERSUS TEMOZOLAMIDE IN HIGH-RISK, LOW-GRADE GLIOMAS: A RETROSPECTIVE COHORT STUDY

Abstract

Abstract INTRODUCTION Low-grade gliomas (LGG), specifically WHO grade 2 diffuse astrocytoma and oligodendroglioma, are increasingly considered for adjuvant chemotherapy with high-risk features (age ≥ 40y or subtotal resection). This is based on prospective studies showing improvement in survival with adjuvant procarbazine, CCNU, vincristine (PCV) or temozolomide (TMZ) in this cohort. Use of PCV or TMZ is variable without published head-to-head comparison. PROTECT is a Canadian multicentre retrospective study aiming to compare overall survival (OS) in high-risk LGGs receiving PCV or TMZ. We are presenting results from The Ottawa Hospital Cancer Centre (TOHCC). METHODS Patients age ≥ 18y with LGG that received PCV or TMZ within 6 months of primary brain tumor resection at TOHCC from 2005 to 2019 were included. The primary outcome is OS. Secondary outcomes include 1)time to progression (TTP), 2)rate of completion of 6 cycles of PCV or TMZ, and 3)rate of hospitalization or death due to chemotherapy-related complications. RESULTS Of 250 cases, 20 patients (11 diffuse astrocytoma, 9 oligodendroglioma) were eligible. IDH status was mutated in 11, wild-type in 1, and unknown in 5 cases. 1p/19q co-deletion was present in 6, non-co-deleted in 1, and unknown in 13 cases. Six patients received PCV, and 14 received TMZ. Hematologic toxicity (CTCAE Grade 1-2) occurred in 3 PCV patients and 0 of 11 of assessable TMZ patients; no severe toxicity was observed. Median follow-up was 64.5 (IQR 42.5–88) months. The median OS and TTP for PCV and TMZ groups were not reached. The 5-year OS and TTP were 75% vs. 100 % (p=0.08) and 83.3% vs 81.3% (p=0.7) respectively. CONCLUSIONS There are insufficient cases and follow-up time to determine OS and TTP amongst patients treated with PCV or TMZ. Hematologic toxicity appears to be more common with PCV. Patient screening and data collection is ongoing at 8 other cancer centres.