Bevacizumab: Is the lower the better for glioblastoma patients in progression?

Introduction: Based on the radiological responses obtained with a schedule of ten mg/kg every two weeks bevacizumab was approved by the FDA for recurrent glioblastomas. Due to the negative results concerning overall survival of patients receiving bevacizumab, the European application was rejected. Despite this, many centers apply an off-label prescription. Our aim was to evaluate the safety and efficacy of schedules of low doses of bevacizumab.

Methods: From September 2013 to August 2016, we recruited patients with progressive glioblastoma, whatever the previous treatments. We compared a routine control group (CG) of ten mg/kg, to a low dose group (LDG) composed of 5 subgroups: G5: five mg/kg, G4: four mg/kg, G3: three mg/kg, G2: two mg/kg, G1: one mg/kg; each patient was treated with the same dose every two weeks.

Results: Fifty-three patients were treated: 20 women and 33 men, 24 in the CG and 29 in the LDG. The median age at diagnosis was 62 years [35.0-77.0]. No statistical difference was found in overall survival either for the CG or the LDG (P=0.086) or among groups (P=0.251), with even a trend toward improvement for LDG: 62 weeks [20-145] versus 73 weeks [18-178]. The median progression free survival was comparable: 19.5 weeks [6.0-54.0] for the CG and 15.0 weeks [0.0-134.0] for the LDG (P=0.221). Bevacizumab was stopped either due to progression (45.1%) or toxicity (52.9%), without significant differences between doses but maybe less toxicities in the LDG (16.7% for toxicity in G1).

Discussion: Use of bevacizumab at progression at lower than usual doses seems to give the same results as the standard dose without giving additional toxicity.