2054 Background: Treatment with a regimen of bevacizumab/irinotecan has been shown to be effective in recurrent grade 3 and 4 gliomas, but the effect of this regimen against recurrent oligodendroglial tumors has not been specifically studied. Methods: The bevacizumab/irinotecan regimen was retrospectively evaluated in a consecutive series of 25 patients with recurrent oligodendroglial tumors. All patients had failed previous treatment with radiation therapy and at least one line of temozolomide chemotherapy. Bevacizumab (10 mg/kg) and irinotecan (125 or 340 mg/m² according to the antiepileptic regimen) were delivered every 14 days. Response was measured clinically and on monthly MRI. Results: The objective response rate was 72% (20% complete response, 52% partial response). After a median follow-up (from the first cycle) of 310 days (95% CI, 47–499), the median progression-free survival was 174 days (95% CI, 116–342), and the median overall survival was 328 days (95%CI, 217-not reached). The 6-month progression-free survival was 42 % (95 % CI, 26% to 67%). Among the 20 patients who progressed at the time of the analysis, the radiological pattern of progression was atypical in seven patients with an isolated multifocal or diffuse spread of the FLAIR signal, or an isolated meningeal spread or FLAIR abnormalities preceding contrast-enhancement recurrence. Among the 10 patients who are still alive, two are still on follow-up since 6 months with a complete response after, respectively, 10 and 12 months of treatment. Among the 17 patients in whom the status of the main molecular alterations of gliomas could be evaluated (search for deletions of chromosomes 1p, 19q, 9p, 10q, and amplification of EGFR, MDM2, CDK4), no relation could be found between the response rate and the type of genetic change (including 1p-19q co-deletion). The profile of tolerance was fair, with treatment discontinuation in 20% of patients. Intratumoral hemorrhages occurred in six patients (24%), but the treatment had to be discontinued because of symptomatic bleeding in only one patient (4%). Conclusions: This regimen is effective in recurrent oligodendrogliomas, and the overall tolerance is acceptable. [Table: see text]