Glioblastoma (GBM) is a type of highly malignant brain tumor with poor prognosis. Epidermal growth factor receptors (EGF-R) have been linked to the oncogenesis of GBM, in which the EGF-RvIII variant is most commonly seen.
Agents targeting EGF-R, such as gefitnib and erlotnib, and monoclonal antibodies like cetuximab, have not demonstrated convincing efficacy for the treatment of GBM, however, antibody mediated therapy and vaccinations are being explored.
Nimotuzumab, a monoclonal antibody that has a greater specificity for EGF-R overexpressing cells compared to cetuximab, has shown promising efficacy for high grade glioma. Investigators conducted a randomized, open label trial to evaluate the efficacy of nimotuzumab in patients with newly diagnosed glioblastoma.
There were 149 patients in the study, stratified as with or without residual tumor, and were randomly assigned to receive either intravenous nimotuzumab added to standard radiotherapy or just standard radiotherapy.
Results showed that the 12-month PFS was seen in 25.6% of patients in the nimotuzumab group, and 20.3% in the control group. Of the patients with residual tumor (n=81), the median PFS was 5.6 months in the nimotuzumab group versus 4.0 months in the control group (HR 0.87; 95%CI, 0.55-1.37), and patients without residual tumor (n=61) 10.6 versus 9.9 months (HR, 1.01; 95%CI, 0.57-1.77).
The median OS in patients with residual tumor was 19.5 months in the nimotuzumab group versus 16.7 months in the control group (HR, 0.90; 95% CI, 0.52-1.57; P=0.7061), and patients without residual tumor 23.3 versus 21.0 months (HR, 0.77; 95% CI, 0.41-1.44; P=0.4068).
A cohort study was conducted on MGMT non-methylated patients with residual tumor and showed a PFS of 6.2 versus 4.0 months (HR, 0.77; 95% CI, 0.35-1.67; P=0.4997), and OS of 19.0 versus 13.8 months (HR, 0.66; 95% CI, 0.27-1.64; P=0.3648).
The authors concluded that EGF-R amplification does not correlate with clinical efficacy of nimotuzumab, and thus alternative explanations should be hypothesized for the treatment of GBM. The results of this study provided important information to plan for future trials.
A randomised, open label phase III trial was conducted to evaluate efficacy of nimotuzumab, a monoclonal antibody against epidermal growth factor receptor (EGF-R) added to standard therapy for newly diagnosed glioblastoma. This study, albeit negative, contains hypothesis generating signals supporting evaluation of correlative, efficacy-predicting tumour parameters for nimotuzumab in the treatment of glioblastoma.