PATTERNS OF RELAPSE AND PROGNOSIS AFTER BEVACIZUMAB FAILURE IN RECURRENT GLIOBLASTOMA

To the Editor:

We commend Iwamoto et al.¹ for their article regarding patterns of relapse and survival in patients treated with bevacizumab (BEV) for recurrent glioblastoma (GBM).

The authors reported on patterns of relapse in 37 adult patients with recurrent GBM treated with BEV. Forty-three percent of patients were treated with BEV plus irinotecan and 38% were treated with BEV plus hypofractionated radiotherapy. The pattern of recurrence prior to BEV-based therapy was not reported. Following progression on BEV and discontinuance of BEV, 35% of patients demonstrated nonenhancing tumor progression, 16% had multifocal disease progression, and 46% had local recurrence. Median survival in patients (19/37) receiving salvage therapy after progression on BEV was 5.2 months compared to 2.0 median survival in patients receiving no further therapy and only supportive care. The survival in patients treated after BEV progression in this report contradicts other data that have shown a median survival of 3 months, which is significant with respect to trial design for patients progressing on BEV.^2–4

Norden et al.⁴ evaluated 55 patients with high-grade gliomas treated with BEV and irinotecan. Twenty-three patients were treated at BEV progression with BEV in addition to a different cytotoxic chemotherapy. Median progression-free survival was 7 weeks. Twenty-six patients were evaluated for pattern of disease progression following progression on BEV and 62% were local and 15% each distant or diffuse. In a non-BEV-treated control group (n = 16), there were similar patterns of radiographic recurrence, suggesting that relapse pattern was not different regardless of salvage therapy.

Finally, Pope et al.⁵ recently delineated 4 …