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Journal of Clinical Oncology, Vol 25, No 16 (June 1), 2007: pp. 2184-2190 © 2007 American Society of Clinical Oncology. DOI: 10.1200/JCO.2006.07.6554 Predictive and Pharmacodynamic Biomarker Studies in Tumor and Skin Tissue Samples of Patients With Recurrent or Metastatic Squamous Cell Carcinoma of the Head and Neck Treated With Erlotinib
From the Princess Margaret Hospital Phase II Consortium; Ontario Cancer Institute, Toronto; National Cancer Institute of Canada Clinical Trials Group, Kingston, Ontario, Canada; Vanderbilt University Medical Center, Nashville, TN; and the National Cancer Institute, Bethesda, MD Address reprint requests to Lillian L. Siu, MD, FRCPC, Department of Medical Oncology and Hematology, Princess Margaret Hospital, University Health Network, 610 University Ave, Suite 5-718, Toronto, Ontario, M5G 2M9, Canada; e-mail: lillian.siu{at}uhn.on.ca
Purpose: Pharmacodynamic tissue studies were conducted on a phase I/II trial of erlotinib and cisplatin in patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). Levels of epidermal growth factor receptor (EGFR), downstream signaling components, and markers of angiogenesis and apoptosis were evaluated to determine the relationship between correlative end points and clinical outcomes.
Patients and Methods: Pretreatment and during-treatment tumor and skin biopsies, and archival tumor specimens were evaluated for EGFR, phosphorylated (p) -EGFR, extracellular signal-regulated kinase (ERK), p-ERK, Akt, p-Akt, Ki67, p27, p-nuclear factor kappa B (NF
Results: On 37 archival samples, response to therapy was evident in two of four (50%) patients with high EGFR gene copy number tumors and in four of 27 (15%) patients with low gene copy number tumors. On nine paired tumor biopsies, elevated pretreatment levels of p27 and p-STAT3 predicted for prolonged time to progression (TTP) and overall survival (OS; P Conclusion: High EGFR gene copy in tumor specimens may predict which patients have an increased likelihood of response to erlotinib, and decreased p-EGFR level in skin biopsies during therapy may represent a potential surrogate marker for improved clinical outcome. MDS represents a novel way to evaluate the relationships between molecular markers and clinical outcome. Additional biomarker studies with larger sample sizes are required to elucidate HNSCC patients who may benefit from this targeted therapy.
Epidermal growth factor receptor (EGFR) and its ligands are fundamental for cell proliferation, motility, adhesion, invasion, and angiogenesis.1 Dysregulation of the EGFR signal transduction pathway plays a critical role in the process of tumor formation, growth, and metastasis.2-4 Biochemical and immunohistochemical studies have demonstrated overexpression of EGFR in a number of solid tumors, including 80% to 90% of head and neck squamous cell carcinomas (HNSCC),5-7 and elevated levels of EGFR protein portend for a decreased disease-free survival.6,8 EGFR inhibition is an important strategy in the treatment of HNSCC. Erlotinib is a small-molecule quinazoline derivative that inhibits autophosphorylation of EGFR tyrosine kinase (TK) and exerts antiproliferative effects resulting in cell cycle arrest and induction of apoptosis.9,10 Preliminary results suggest that erlotinib inhibits EGFR signaling at the tumor level, and that p27 upregulation may represent a marker of effective downstream inhibition in skin tissues.11,12 To maximize the clinical potential of erlotinib in HNSCC and expand on the single-agent activity,13 its use in combination with cisplatin was evaluated in a phase I/II trial. Pre- and during treatment levels of EGFR, its downstream signaling components, and markers of angiogenesis and apoptosis in tumor and skin biopsies were examined to determine the relationship between these correlative end points and clinical outcome.
Clinical Study Tumor and skin samples were procured from participants in a phase I/II trial of erlotinib and cisplatin in recurrent or metastatic HNSCC. Eligible patients were treated either in the phase I portion of the trial or at the recommended phase II dose of erlotinib 100 mg orally daily on a continuous schedule and cisplatin 75 mg/m2 intravenously on day 1 every 21 days. For the first cycle, erlotinib was taken alone for 7 days (days 6 to day 0) as a run-in period, to enable a steady-state concentration before initiating cisplatin. The primary end point was objective response rate assessed using Response Evaluation Criteria in Solid Tumors.14 Secondary end points included clinical parameters of efficacy, safety assessments, and molecular correlations using tumor and skin biopsies. Separate written consent was obtained for optional tissue banking and correlative studies. Institutional review board approval was obtained at all participating centers.
Tissue Acquisition
Immunohistochemistry and Immunofluorescence For IHC and IF, sections were pretreated with 0.4% pepsin, pH 2.0, or subjected to antigen retrieval in a Milestone T/T Mega microwave oven (Milestone srl, Sorisole [BG], Italy) for 10 minutes at 120°C in 10 mmol/L citrate buffer, pH 6.0. After cooling, sections were covered with normal serum and incubated in primary antibodies. IF tumor biopsies were dual stained with antibodies against the marker protein and cytokeratin (cocktail of Dako monoclonal antibodies to AE1/AE3, HMWK, CK7, CK20 or Dako rabbit polyclonal antikeratin wide spectrum screening; Dako Cytomation, Carpinteria, CA) to identify epithelial tumor cells. After primary antibody incubation, slides were rinsed in phosphate-buffered saline and secondary antibodies (Cy5 conjugate, specific to the cell signaling markers, and Cy3 conjugate, specific to the cytokeratin) were applied for 30 minutes at room temperature in darkness. Sections were counterstained with the DNA-specific dye 4,6-diamidino-2-phenylindole (DAPI; Roche Applied Science, Laval, Quebec, Canada) at 1 µg/mL for 5 minutes at 4°C, then rinsed twice for 5 minutes with distilled water and air dried.
Image Analysis IHC-stained biopsies were acquired using Zeiss transmitted-light microscope (Carl Zeiss, Oberkochen, West Germany), 20x objective, motorized stage, and a Sony DXC970 color camera (Toyko, Japan) controlled by MCID Elite software (St Catherine's, Ontario, Canada). Manually selecting the epidermis and setting a threshold on positive NovaRed stained areas, the software computed the proportional positive stained area for all markers except p27 and Ki67, for which the estimated number of positive nuclei per tumor area with mean nuclear size of 75 µm2 was determined.
IHC Scoring
Fluorescent In Situ Hybridization and Analysis Analyses were done with a fluorescence microscope by two independent observers (G.C.S. and P.M.). The observers were blinded to the patient's clinical response and each other's assessments. One hundred nonoverlapping interphase nuclei were scored for EGFR and CEP7 copy number and classified into six categories, as reported previously.18,19
Statistical Analysis To provide an analysis of multiple markers at the same time, multidimensional scaling (MDS) was used.20 MDS can be considered to be an alternative to factor analysis. MDS is a data analysis technique that displays the structure of distance-like data as a geometric picture. MDS illustrates the structure of a set of study samples from data that approximate the distances between pairs of the study samples. Two similar study samples are represented by two points that are close together, and two dissimilar study samples are represented by two points that are far apart. The result of MDS is usually a three-dimensional Euclidean space.
Samples Available for Analysis and Clinical Outcomes Of the 51 patients accrued for enrollment onto the phase I/II trial, 42 archival tumor samples from 37 different patients, 32 paired skin and nine paired tumor biopsy samples were available for analysis. Response rates, time to progression (TTP) and overall survival (OS) for these patients are outlined in Table 1. Details of the clinical results of this study are provided in a companion article.21
Archival Tumor Samples FISH was used to assess the EGFR gene copy number on all archival tumor samples and complete analysis was achieved on 32 (86%) samples (Table 2). Patients with high EGFR gene copy numbers (amplification and high polysomy) are designated as FISH positive and patients in all other categories are designated FISH negative. FISH-positive patients had a high response rate to therapy (two of four; 50%), longer TTP (3.5 months), and a median survival of 7.1 months. Among FISH-negative patients, response to therapy was observed in four of 27 patients (15%), and TTP and median OS were 2.8 and 5.6 months, respectively (Fig 1).
Among the 37 patients whose archival tumor samples were subjected to IHC analysis, 36 samples (97%) were EGFR positive. The relationships among EGFR status, clinical parameters of tumor response, TTP, and OS are summarized in Table 2. Of those patients with 67% of cells staining for EGFR, six of 24 (25%) responded to therapy, whereas only one of 11 (9%) patients with less than 67% of cells staining for EGFR achieved an objective response. With respect to EGFR staining intensity, objective responses were seen in five (36%) of 14 patients with strong staining intensity, compared with two (10%) of 21 patients who had weaker or no staining intensity. No statistically significant association between FISH and IHC evaluation of EGFR status was established.
Paired Tumor Biopsies
MDS was used to explore the impact of the simultaneous grouping of expression levels of multiple markers on response rates, TTP, or OS. These models illustrated that expression levels of tumor markers by IF can predict for response (Appendix Fig A1A, online only). No clustering patterns were visualized when IHC evaluation of tumor markers was used. MDS graphs did not illustrate clustering patterns as predictors of TTP or OS (Appendix Fig A1B, online only).
Paired Skin Biopsies MDS graphs were established from the paired skin samples in an identical way as that for the paired tumor biopsy samples. No distinct clustering patterns in the three-dimensional models were visualized when associating grouped skin markers with responses, TTP, or OS (Appendix Fig A1C, online only).
Erlotinib as a single agent has been shown to produce prolonged disease stabilization in patients with recurrent or metastatic HNSCC.13 Identification of a subset of patients who may benefit the most from erlotinib therapy has not been well established in this disease. Our study sought to establish if baseline levels of EGFR expression and receptor phosphorylation status in tumor and skin biopsy samples could predict outcome to therapy, if the effect of erlotinib on downstream signaling components can be measured in tumor and skin tissues, and if skin biopsies can be used as a surrogate to predict or follow clinical outcome. To the best of our knowledge, this study is the first to suggest that HNSCC patients with high gene copy number may have higher response rates to erlotinib therapy than patients with low EGFR gene copy number. Three recent reports, in patients with nonsmall-cell lung cancer (NSCLC), confirmed an association between high EGFR gene copy number with either survival or response to EGFR TK inhibitor therapy. Cappuzzo et al19 reported on NSCLC patients treated with gefitinib, and showed a statistically significant survival advantage for patients with EGFR FISH-positive tumors. Similar results were seen in a subset of patients with lung adenocarcinoma with bronchoalveolar growth pattern.22 Tsao et al18 have recently confirmed, by univariate analysis, a prolonged survival in EGFR FISH-positive NSCLC patients treated with erlotinib; however, by multivariate analysis, this advantage was not conferred. Most previous studies have found the expression of EGFR protein in archival specimens by IHC an unreliable predictor of responsiveness to EGFR inhibitor therapies.23-25 Consistent with the phenotype of squamous cell carcinoma, we found that nearly all of our patients expressed the EGFR protein, thus rendering the differentiation of clinical outcome between EGFR-positive and -negative patients to be statistically impossible. We then attempted to analyze our results by stratification based on percentage of positively stained cells and intensity of staining. Response rates tended to favor those patients with increased percentage of cells staining for EGFR and those with increased staining intensity. Other studies have not demonstrated this association26 and most recently a study of the anti-EGFR monoclonal antibody cetuximab in HNSCC has shown the opposite finding.27 It should be reminded that IHC is a subjective assay lacking the dynamic range for quantitative evaluation of protein expression level. With most HNSCC expressing high EGFR protein, the lack of correlation between EGFR gene dosage and the IHC protein levels is not surprising, as demonstrated by our data and that of Mrhalova et al.28 With EGFR TK inhibition by erlotinib, downstream effector signals are expected to decrease and theoretically, p27 should be increased.9,10 We observed a decrease in p27 in patients receiving erlotinib therapy that was associated with improved survival outcomes. A concern has arisen about the potential antagonistic effect of EGFR inhibitors and chemotherapeutic agents.29,30 Although cytotoxic chemotherapeutic agents act on dividing cells, EGFR inhibitors cause G1 cell cycle arrest. By causing this cell cycle arrest, erlotinib may antagonize the antitumor effects of cisplatin. It is therefore a possibility that patients whose tumor cells continued to proliferate and did not undergo cell cycle arrest, despite erlotinib, were more likely to experience benefits from cisplatin and thus had an improved survival outcome with an observed decrease in p27.
As a prognostic marker, overexpression of p-NF Given the small number of samples obtained, and by comparison, the large number of markers evaluated, individual examinations of the effects of each marker on objective response, TTP, and OS by univariate analyses are plagued by multiple significance testing and are statistically flawed. From our nine paired tumor biopsy samples and 32 paired skin biopsy samples, the only uniform finding was that a decrease in p-EGFR level after 1 week of erlotinib in both tissue types was associated with increased TTP and OS, respectively. Therefore, p-EGFR may represent a useful surrogate pharmacodynamic marker of erlotinib effect in recurrent or metastatic HNSCC. Our group has shown similar results of a decreased p-EGFR level in tumor tissue during treatment with erlotinib for patients with metastatic colorectal cancer.17 Recent publications have explored the role of MDS as a means to visualize multiple results without the use of a P value.33-35 Our MDS models illustrated that clustering patterns of molecular markers in tumor biopsy samples may help distinguish responders from nonresponders, but no significant patterns were identified using the skin samples from our patients. Although MDS models of baseline and during treatment expressions of tumor markers seemed to predict for objective responses with erlotinib, no associations with TTP or OS were found. This study illustrates that when serial tumor biopsies are optional rather than mandatory, a paucity of research samples are obtained. Given the number of assessable samples, the inclusion of multiple markers for analysis, the issue of tumor heterogeneity, the variability of reagents and antibodies used, and the differences in sample handling and storage procedures, it becomes difficult to draw definitive conclusions with sufficient power. Although our ability to formulate any association between tumor or surrogate tissue samples with clinical outcome is limited, additional evaluation of the association between EGFR gene copy and response to EGFR inhibition in HNSCC needs to be explored.
Although all authors completed the disclosure declaration, the following authors or their immediate family members indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. For a detailed description of the disclosure categories, or for more information about ASCO's conflict of interest policy, please refer to the Author Disclosure Declaration and the Disclosures of Potential Conflicts of Interest section in Information for Contributors. Employment: N/A Leadership: N/A Consultant: Denis Soulieres, Hoffman-La Roche Inc; Suzanne Kamel-Reid, Genentech Stock: N/A Honoraria: Denis Soulieres, Hoffman-La Roche Inc; Ming S. Tsao, Hoffman-La Roche Inc Research Funds: Denis Soulieres, Hoffman-La Roche Inc Testimony: N/A Other: N/A
Conception and design: David Hedley, Janet Dancey, Lillian L. Siu, Ming S. Tsao Administrative support: Janet Dancey Provision of study materials or patients: Eric Winquist, Denis Soulieres, Eric X. Chen, Lillian L. Siu Collection and assembly of data: Gilda da Cunha Santos, David Hedley, Trudey Nicklee, Patricia Pintor dos Reis, James Ho, Gregory R. Pond, Jeremy A. Squire, Paula Marrano, Suzanne Kamel-Reid, Ming S. Tsao Data analysis and interpretation: Mark Agulnik, Gilda da Cunha Santos, David Hedley, Trudey Nicklee, Patricia Pintor dos Reis, James Ho, Gregory R. Pond, Heidi Chen, Shuo Chen, Yu Shyr, Jeremy A. Squire, Paula Marrano, Suzanne Kamel-Reid, Lillian L. Siu, Ming S. Tsao Manuscript writing: Mark Agulnik Final approval of manuscript: Mark Agulnik, Gilda da Cunha Santos, David Hedley, Trudey Nicklee, Patricia Pintor dos Reis, James Ho, Gregory R. Pond, Heidi Chen, Shuo Chen, Yu Shyr, Eric Winquist, Denis Soulieres, Eric X. Chen, Jeremy A. Squire, Paula Marrano, Suzanne Kamel-Reid, Janet Dancey, Lillian L. Siu, Ming S. Tsao
Supported in part by National Cancer Institute Contract No. N01-CO-124001, Subcontract No. 22XS035A-P5380. Presented in part at the Annual American Association for Cancer Research- National Cancer Institute-European Organization for Research Treatment of Cancer-Molecular Targets and Cancer Therapeutics Conference, November 14-18, 2005, Philadelphia, PA. M.A. and G.d.C.S. contributed equally to this work. Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
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Copyright © 2007 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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