The epidermal growth factor receptor (EGFR) is a validated target in squamous cell carcinoma of the head and neck but in patients with recurrent or metastatic disease, EGFR targeting agents have displayed modest efficacy. Vascular endothelial growth factor (VEGF) mediated angiogenesis has been implicated as a mechanism of resistance to anti-EGFR therapy. This study combined an EGFR inhibitor, erlotinib, with an anti-VEGF antibody, bevacizumab.
This multi-institutional phase I/II study enrolled patients with recurrent or metastatic squamous cell carcinoma of the head and neck to receive erlotinib (150 mg daily) and bevacizumab in escalating dose cohorts. The primary objectives in the phase I and II portions, respectively, were to determine the maximum tolerated dose and dose-limiting toxicity of bevacizumab when administered with erlotinib and to determine the objective response rate and time to disease progression. Pre-treatment serum and tissues were collected and analyzed by Enzyme-Linked ImmunoSorbent Assay and immunofluorescence quantitative laser analysis, respectively. This study was registered with ClinicalTrials.gov, number NCT00055913.
The phase I portion enrolled 10 subjects in three successive cohorts without dose-limiting toxicity observed. An additional 46 subjects were enrolled at the phase II dose (bevacizumab 15 mg/kg every 3 weeks). The most common toxicities of any grade were rash and diarrhea (41 and 16 of 48 subjects, respectively). Three patients experienced serious bleeding events. The observed response rate was 15% with 4 complete responses (CR) allowing rejection of the null hypothesis. The median overall and progression-free survival (PFS) durations were 7.1 (95% Confidence Interval: 5.7 to 9.0) and 4.1 (95% Confidence Interval: 2.8 to 4.4) months, respectively. Higher ratios of phosphorylated over total VEGF receptor-2 and EGFR in pre-treatment biopsies were associated with CR (0.7043 vs. 0.3857, p=0.036 and 0.949 vs. 0.332, p=0.036, respectively) and tumor shrinkage (p=0.007 and p=0.008, respectively) in a subset of 11 subjects with available tissue.
The combination of erlotinib and bevacizumab is well tolerated in recurrent or metastatic squamous cell carcinoma of the head and neck. Some patients appear to derive a sustained benefit and complete responses were associated with expression of putative targets in pre-treatment tumor tissue.