Background 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. Methods 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. Findings 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. Interpretation 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.

Purpose: An objective response rate of 11% was reported in patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN) treated with 500 mg daily gefitinib although the recommended dose in lung cancer is 250 mg. This study evaluated the efficacy and toxicity of 250 mg daily gefitinib in patients with recurrent and/or metastatic SCCHN. Experimental Design: Phase II trial with objective response rate as the primary end point. Measurements of quality of life and levels of serum vascular endothelial growth factor and transforming growth factor-a were assessed before and during therapy. Results: In 70 patients,1 (1.4%) partial response was observed. Median progression-free survival and overall survival were 1.8 and 5.5 months, respectively. Quality of life scores improved transiently during the first weeks of therapy before returning to baseline. Median vascular endothelial growth factor and transforming growth factor-a levels were above the normal range but were not predictive of outcome. Four patients experienced grade 3 drug-related adverse events. Rash of any grade was observed in 64% of subjects. Correlation between disease control (partial response + stable disease), progression-free survival, and overall survival and grade of cutaneous toxicity was observed (P = 0.001, 0.001, and 0.008 respectively). Conclusions: Gefitinib monotherapy at 250 mg in recurrent and/or metastatic SCCHN seems to have less activity than was previously observed for 500 mg daily. A dose-response relationship may exist for this agent in SCCHN and grade of cutaneous toxicity attributable to gefitinib is a clinical predictor of better outcome.

Protein kinase C (PKC) Z has been implicated as a mediator of epidermal growth factor (EGF) receptor (EGFR) signaling in certain cell types. Because EGFR is ubiquitously expressed in squamous cell carcinomas of the head and neck (SCCHN) and plays a key role in tumor progression, we determined whether PKCZ is required for tumor cell proliferation and viability. Examination of total and phosphorylated PKCZ expression in normal oral mucosa, dysplasia, and carcinoma as well as SCCHN tumor cell lines revealed a significant increase in activated PKCZ expression from normal to malignant tissue. PKCZ activity is required for EGF-induced extracellular signalregulated kinase (ERK) activation in both normal human adult epidermal keratinocytes and five of seven SCCHN cell lines. SCCHN cells express constitutively activated EGFR family receptors, and inhibition of either EGFR or mitogenactivated protein kinase (MAPK) activity suppressed DNA synthesis. Consistent with this observation, inhibition of PKCZ using either kinase-dead PKCZ mutant or peptide inhibitor suppressed autocrine and EGF-induced DNA synthesis. Finally, PKCZ inhibition enhanced the effects of both MAPK/ERK kinase (U0126) and broad spectrum PKC inhibitor (chelerythrine chloride) and decreased cell proliferation in SCCHN cell lines. The results indicate that (a) PKCZ is associated with SCCHN progression, (b) PKCZ mediates EGF-stimulated MAPK activation in keratinocytes and SCCHN cell lines, (c) PKCZ mediates EGFR and MAPK-dependent proliferation in SCCHN cell lines; and (d) PKCZ inhibitors function additively with other inhibitors that target similar or complementary signaling pathways. (Cancer Res 2006; 66(12): 6296-303)

Despite nearly universal expression of the wild-type epidermal growth factor receptor (EGFR) and reproducible activity of EGFR inhibitors in patients with squamous cell carcinoma of the head and neck (SCCHN), the majority of patients will not have objective responses. The mechanisms of this intrinsic resistance are not well established. We hypothesized that sensitivity to EGFR inhibitors can be predicted based on the inhibitors’ effects on downstream signaling. Cell viability assays were used to assess sensitivity to the EGFR inhibitor gefitinib (ZD1839) in 8 SCCHN cell lines. Fluorescence in-situ hybridization showed the two most sensitive lines to be highly gene-amplified for EGFR. Western blotting confirmed that phosphoEGFR was inhibited at low concentrations of gefitinib in all lines tested. Phosphorylation of downstream signaling protein AKT was inhibited in sensitive lines while inhibition of phosphoERK displayed no relationship to gefitinib efficacy. Phosphatase and tensin homolog (PTEN) expression was evident in all cell lines. Activating PIK3CA mutations were found in two resistant cell lines where pAKT was not inhibited by gefitinib. In resistant cell lines harboring PIK3CA mutations, a PI3K inhibitor, LY294002, or AKT siRNA reduced cell viability with an additive effect demonstrated in combination with gefitinib. Additionally, LY294002 alone and in combination with gefitinib, was effective at treating PIK3CA mutated tumors xenografted into nude mice. Taken together this suggests that constitutively active AKT is a mechanism of intrinsic gefitinib resistance in SCCHN. This resistance can be overcome through targeting of the PI3K/AKT pathway in combination with EGFR inhibition.