Retrospective study of carmustine or lomustine with bevacizumab in recurrent glioblastoma patients who have failed prior bevacizumab

Background. Currently, there are no known effective treatments for recurrent glioblastoma once patients have progressed on a bevacizumab-containing regimen. We examined the efficacy of adding nitrosoureas to bevacizumab in patients who progressed while on an initial bevacizumab-containing regimen. Methods. In this retrospective study, we identified adult patients with histologically confirmed glioblastoma (WHO grade IV) who were treated with lomustine or carmustine in combination with bevacizumab as a second or third regimen after failing an alternative initial bevacizumab-containing regimen. Response rate (RR), 6-month progression free survival (PFS6), and progression-free survival (PFS) were assessed for each treatment. Results. Forty-two patients were identified (28 males) with a median age of 49 years (range, 24-78 y). Of 42 patients, 28 received lomustine (n = 22) or carmustine (n = 6) with bevacizumab as their second bevacizumab-containing regimen, and 14 received lomustine (n = 11) or carmustine (n = 3) as their third bevacizumab-containing regimen. While the median PFS for the initial bevacizumab-containing regimen was 16.3 weeks, the median PFS for the nitrosourea-containing bevacizumab regimen was 6.3 weeks. Patients had an RR of 44% and a PFS6 rate of 26% during the initial bevacizumab regimen and an RR of 0% and a PFS6 rate of 3% during the nitrosourea-containing bevacizumab regimen. There was increased grade 3-4 toxicity (45% vs 19%, P = .010) during the nitrosourea-containing bevacizumab regimen relative to the initial bevacizumab regimen. Median overall survival was 18.7 weeks from initiation of the nitrosourea-containing bevacizumab regimen. Conclusion. The addition of lomustine or carmustine to bevacizumab after a patient has already progressed on a bevacizumab-containing regimen does not appear to provide benefit for most patients and is associated with additional toxicity with the doses used in this cohort.