Weekly vinblastine in chemotherapy-naive children with unresectable or progressive low grade glioma: A Canadian cooperative study.

10029 Background: Vinblastine has shown promising activity in a phase II study in children with recurrent/refractory LGG. The aim of this study was to assess the activity of vinblastine in chemotherapy naïve children. Methods: Patients < 18 years old with unresectable or progressive LGG were eligible if they had not received any previous treatment with chemotherapy or radiation. Vinblastine was administered weekly at a dose of 6 mg/m 2 over a period of 70 weeks. Patients who showed progression on 2 consecutive imaging studies or evidence of clinical progression were removed from treatment. Results: 54 patients (23 female) were enrolled between 2007 and 2010. Median age at inclusion was 7 years, 13 patients were < 3 years. 32 had chiasmatic/hypothalamic tumours, 6 had evidence of dissemination. 13 had neurofibromatosis type 1. Histology was pilocytic astrocytoma (25), pilomyxoid astrocytoma (4), low grade astrocytoma variant (8); 17 patients had no histological diagnosis. Treatment was well tolerated; however, only 14 patients received full dose for the duration of the study. Most common toxicity was haematological: 40 patients who experienced grade 3+ neutropenia. There were only 6 episodes of febrile neutropenia, 3 RBC transfusions and no toxic death. Best response to chemotherapy was assessed centrally by an independent radiologist: 1 CR, 10 PR, 3 MR, 28 SD, 12 PD, for a response rate of 24.5%. With a median follow-up of 2 years (9-48 months), progression-free survival at 2 years was 72.1% (95%CI: 58.1-82.2). One patient died of progression. Conclusions: Weekly vinblastine is well tolerated in paediatric LGG patients. Although the response rate appears inferior to other common LGG regimens, progression free survival at 2 years favourably compares to most currently used regimens. Supported by a grant from the Ontario Institute Cancer Research. Clinical trial information: 1000011227.