A stratified phase II study of cetuximab for the treatment of recurrent glioblastorna multiforme: Preliminary results.

Background: The Epidermal Growth Factor Receptor (EGFR) gene is frequently amplified and mutated in high-grade gliomas. We are investigating the activity of the EGFR-targeted monoclonal antibody cetuximab for the treatment of patients (pts) with recurrent glioblastoma multiforme (GBM) following surgery, radiotherapy and chemotherapy. Methods: Adult pts with recurrent GBM are allocated to two parallel treatment strata according to the amplification status of the EGFR gene (determined by FISH). According to a Simon two-stage phase II study design 1 response in 13 pts/stratum is required to continue recruitment and complete the second stage of pt recruitment. Cetuximab is administered at 400 mg/m2 (2 hour infusion) day 1 and 250 mg/m2 day 8 and for all subsequent weekly doses (1 hour infusion).
Results: Between May and December 2005, 17 pts were recruited (10 without EGFR-ampl, 4 with EGFR-ampl and 3 under investigation); 4F/13M; median age 51 years, range 32-67). Recruitment is ongoing. Sixteen pts initiated study treatment; 1 pt withdrew consent before the initiation of therapy. Treatment related toxicity in the first 94 treatment cycles consisted of grade 1/2 folliculitis/dermitis in all treated pts. Grade 3 adverse events consisted of thrombocytopenia (n=1 pt), diminished consciousness (n=1 pt), dizziness/confusion (n=1 pt), infectious bronchopneumonia (n=1 pt), and infectious cellulitis (n=1 pt). Thirteen pts have been evaluated for response week 8 of study treatment. Eleven pts had progression of disease. Two patients had SD at 8 weeks (follow-up is ongoing).
Conclusions: These preliminary data suggest that cetuximab can be safely administered to pretreated patients with recurrent GBM. Updated results regarding safety and activity as well as a correlative study of EGFR and PTEN expression and gene copy number of the GBM and response to cetuximab will be presented at the meeting.