Effects of Gefitinib on Serum Epidermal Growth Factor Receptor and HER2 in Patients with Advanced Non-Small Cell Lung Cancer

"Sandwich" Strategy to Intensify EGFR Blockade by Concurrent Tyrosine Kinase Inhibitor and Monoclonal Antibody Treatment in Highly Selected Patients

EGFR TKIs are not curative, and targeted resistance inevitably results in therapeutic failure. Additionally, there are numerous uncommon EGFR mutations that are insensitive to EGFR TKIs, and there is a lack of clinical strategies to overcome these limitations. EGFR TKI and mAbs target EGFR at different sites, and a combination regimen for delaying/preventing resistance to targeted therapy or obtaining more intensive inhibition for uncommon mutations at cellular, animal and human levels has been explored. This review critically focuses on a combination strategy for uncommon EGFR mutation-positive NSCLC, and discuss the preclinical data, clinical implications, limitations and future prospects of the combination strategy.

Prognostic impact of serum levels of EGFR and EGFR ligands in early-stage breast cancer

Epidermal growth factor receptor (EGFR) and its ligands are involved in cancer pathogenesis. The emerging role of treatments co-targeting the EGFR system in breast cancer has increased the need to identify companion biomarkers. The aim of this study is to investigate whether pretreatment serum levels of EGFR and EGFR ligands in early-stage breast cancer patients might provide prognostic information as a stepping stone for further investigation. The study, which included 311 early-stage breast cancer patients, investigated associations between preoperative serum levels of EGFR and EGFR ligands (epidermal growth factor, heparin-binding epidermal growth factor (HBEGF), amphiregulin, transforming growth factor-α and betacellulin) and survival. Cutoffs were determined using Youden’s method, and overall survival (OS) and invasive disease-free survival (IDFS) were evaluated using Cox regression. Preoperative S-EGFR < 60.3 ng/mL was associated with shorter OS and IDFS in both univariate analyses and when adjusting for standard prognostic factors (p < 0.05). Preoperative S-HBEGF < 21.4 pg/mL was associated with shorter OS in both univariate and multivariate analyses, whereas association with shorter IDFS could only be demonstrated in the univariate analysis. In conclusion, our study demonstrated shorter survival in early-stage breast cancer patients who had low pretreatment levels of either S-EGFR or S-HBEGF.

EGFR and EGFR ligands in serum in healthy women; reference intervals and age dependency

Background The epidermal growth factor receptor (EGFR) system is involved in cancer pathogenesis and serves as an important target for multiple cancer treatments. EGFR and its ligands epidermal growth factor (EGF), heparin-binding epidermal growth factor (HB-EGF), betacellulin (BTC), amphiregulin (AREG) and transforming growth factor α (TGF-α) have potential applications as prognostic or predictive serological biomarkers in cancer. The aim was to establish EGFR and EGFR ligand reference intervals in healthy women. Methods EGFR and EGFR ligands were measured in serum from 419 healthy women aged 26-78 years. The need for age partitioned reference intervals was evaluated using Lahti's method. EGFR and EGF were analyzed using ELISA assays, whereas HB-EGF, BTC, AREG and TGF-α were analyzed using the highly sensitive automated single molecule array (Simoa) enabling detection below the lower reference limit for all six biomarkers. Results Reference intervals for EGFR and the EGFR ligands were determined as the 2.5th and 97.5th percentiles. All six biomarkers were detectable in all serum samples. For EGFR, EGF, HB-EGF and TGF-α, reference intervals were established for women <55 years and for women >55 years, whilst common reference intervals were established for AREG and BTC including women aged 26-78 years. Conclusions Age specific reference intervals were determined for EGFR, EGF, HB-EGF, BTC, AREG and TGF-α.

Cisplatin and 5-fluorouracil with or without epidermal growth factor receptor inhibition panitumumab for patients with non-resectable, advanced or metastatic oesophageal squamous cell cancer: a prospective, open-label, randomised phase III AIO/EORTC trial (POWER)

BACKGROUND

Palliative chemotherapy of advanced oesophageal squamous cell cancer (ESCC) consists of cisplatin/5-fluorouracil (CF) to target epidermal growth factor receptor (EGFR) with panitumumab (P); chemotherapy enhanced overall survival (OS) in advanced colorectal or squamous cell head and neck cancers. With prospective serum and tumour biomarkers, we tested if P added to CF (CFP) improved OS in advanced ESCC.

PATIENTS AND METHODS

Eligible patients with confirmed ESCC that was not curatively resectable or did not qualify for definitive radiochemotherapy, were randomised 1 : 1 to receive CF [cisplatin (C) 100 mg/m² i.v., day 1; 5-fluorouracil (F) 1000 mg/m² i.v., days 1-4] or CF plus P (9 mg/kg, i.v., day 1, each q3-week cycle) until progressive disease or unacceptable toxicity. Safety was reviewed by the Data Safety Monitoring Board after 40, 70 and 100 patients who completed at least one cycle. After 53 enrolled patients, cisplatin was reduced from 100 mg/m² to 80 mg/m².

RESULTS

The trial was stopped early based on interim efficacy results triggered by the third safety analysis: median OS (mOS) favoured CF over CFP, regardless of cisplatin dose [hazard ratio (HR) 1.77, 95% confidence interval (CI) 1.06-2.98; P = 0.028]. In the final analysis, mOS was 10.2 versus 9.4 months for CF versus CFP, respectively (HR 1.17, 95% CI 0.79-1.75; P = 0.43). One hundred (70.4%) of 142 patients in the safety population died, 51 (51.0%) with CFP. Most deaths were related to disease progression [44/49 (90%) deaths in CF versus 34/51 (67%) deaths in CFP]; objective responses [27/73 (37.0%)] were identical. The most common serious adverse events were kidney injury [3 (4.3%) versus 7 (9.7%)], general health deterioration [5 (7.1%) versus 5 (6.9%)] and dysphagia [4 (5.7%) versus 4 (5.6%)] in CF versus CFP, respectively. There were three (4.3%) and 17 (23.6%) common terminology criteria for adverse events (CTCAE) grade 5 events in CF versus CFP, respectively. Low soluble (s)EGFR levels were associated with better progression-free survival; sEGFR was induced under CFP.

CONCLUSION

EGFR inhibition added to CF did not improve survival in unselected advanced ESCC patients. The results support further liquid biopsy studies.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01627379) and EudraCT (2010-020606-15).

Prognostic and predictive value of EGFR and EGFR-ligands in blood of breast cancer patients: a systematic review

Epidermal growth factor receptor (EGFR) serves as a co-target for dual/pan-EGFR-inhibitors in breast cancer. Findings suggest that EGFR and EGFR-ligands are involved in resistance towards certain breast cancer treatments. The aim is to explore the validity of EGFR and EGFR-ligands in blood as prognostic and predictive biomarkers in breast cancer. The systematic review was conducted in accordance to the PRISMA guidelines. Literature searches were conducted to identify publications exploring correlations between EGFR/EGFR-ligands in serum/plasma of breast cancer patients and prognostic/predictive outcome measures. Sixteen publications were eligible for inclusion. Twelve studies evaluated EGFR, whereas five studies evaluated one or more of the EGFR-ligands. Current evidence indicates associations between low baseline serum-EGFR and shorter survival or reduced response to treatment in patients with advanced breast cancer, especially in patients with estrogen and/or progesterone receptor positive tumors. The prognostic and predictive value of EGFR and EGFR-ligands in blood has only been investigated in highly selected subsets of breast cancer patients and most studies were small. This is the first systematic review evaluating the utility of EGFR and EGFR-ligands as predictive and prognostic biomarkers in blood in breast cancer. Further exploration in large well-designed studies is needed.

Impact of menopausal status and HER-2/neu protein on efficacy of EGFR-TKI in EGFR mutant patients with non-small cell lung cancer

Clinical studies have confirmed epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) used in lung cancer patients with EGFR mutations can obtain a better result, but still part of the patients with poor efficacy. EGFR mutation is highly related to female, nonsmoking and adenocarcinoma. Thus, we hypothesize that estrogen and circulating HER-2/neu protein might influence the efficacy of EGFR-TKIs in EGFR mutant patients with non-small cell lung cancer. HER-2/neu expression level of 357 eligible patients in its peripheral serum was determined using ELISA. The median progression-free survival (PFS) in five groups (premenopausal group, perimenopause group, peri to postmenopausal group, postmenopausal group and control group) was statistically difference (P = 0.025). Premenopausal group could predict the efficacy of EGFR-TKI (HR = 2.45, 95% CI = 1.42-4.23, P = 0.001). No statistical significance was found in median overall survival (OS) among five groups. Optimal diagnostic cut off value of HER-2/neu was set at 47.5 ng/ml, with P = 0.0607. As the cutoff value to 47.5 ng/ml division, concentrations and menopausal status was of no significant difference (P = 0.874). PFS of the group below 47.5 ng/ml was significantly longer than that of the group over 47.5 ng/ml (P = 0.000). HER-2/neu concentration was positively correlated with optimal efficacy (P = 0.042). HER-2/neu concentration over than 47.5 ng/ml was a risk factor of EGFR-TKI prognosis. Premenopausal status is an independent predictor of EGFR-TKI curative effect and circulating HER-2/neu protein is an independent prognostic factor in patients with advanced NSCLC.

Safety and efficacy of dacomitinib in korean patients with KRAS wild-type advanced non-small-cell lung cancer refractory to chemotherapy and erlotinib or gefitinib: a phase I/II trial

INTRODUCTION

Dacomitinib (PF-00299804), an irreversible pan-human epidermal growth factor receptor ([HER]-1/EGFR, HER-2, and HER-4) tyrosine kinase inhibitor, demonstrated antitumor activity in Western patients with non-small-cell lung cancer (NSCLC) at a dose of 45 mg once daily. We report data from a phase I/II, multicenter, open-label study of Korean patients with refractory KRAS wild-type adenocarcinoma NSCLC (defined as patients with evidence of disease progression during or within 6 months of treatment with chemotherapy and gefitinib or erlotinib).

METHODS

The phase I dose-finding portion identified the recommended phase II dose (RP2D) in Korean patients, evaluated safety, and characterized the pharmacokinetics of dacomitinib. In the phase II portion, patients received dacomitinib at the RP2D. The primary end point was progression-free survival at 4 months (PFS4m).

RESULTS

Twelve patients enrolled in phase I, and 43 patients enrolled in phase II at the RP2D of 45 mg once daily. In phase II, PFS4m was 47.2% (95% confidence interval [CI], 31.6-61.3; one-sided p-value = 0.0007). Median PFS was 15.4 weeks (95% CI, 9.7-17.6); median overall survival was 46.3 weeks (95% CI, 32.7-not reached); and the objective response rate was 17.1% (95% CI, 7.2-32.1). Common treatment-related adverse events were dermatitis acneiform, diarrhea, and paronychia; there were no treatment-related grade 4 or 5 adverse events. Pharmacokinetic parameters of dacomitinib in Korean patients were similar to those reported in Western patients. By patient report, NSCLC symptoms "cough" and "pain" showed improvement within 3 weeks of initiating treatment.

CONCLUSIONS

Dacomitinib was well tolerated and had antitumor activity in Korean patients with NSCLC who had previously progressed on chemotherapy and an epidermal growth factor receptor tyrosine kinase inhibitor.

Preliminary Evidence on the Diagnostic and Molecular Role of Circulating Soluble EGFR in Non-Small Cell Lung Cancer

Assessment of biological diagnostic factors providing clinically-relevant information to guide physician decision-making are still needed for diseases with poor outcomes, such as non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) is a promising molecule in the clinical management of NSCLC. While the EGFR transmembrane form has been extensively investigated in large clinical trials, the soluble, circulating EGFR isoform (sEGFR), which may have a potential clinical use, has rarely been considered. This study investigates the use of sEGFR as a potential diagnostic biomarker for NSCLC and also characterizes the biological function of sEGFR to clarify the molecular mechanisms involved in the course of action of this protein. Plasma sEGFR levels from a heterogeneous cohort of 37 non-advanced NSCLC patients and 54 healthy subjects were analyzed by using an enzyme-linked immunosorbent assay. The biological function of sEGFR was analyzed in vitro using NSCLC cell lines, investigating effects on cell proliferation and migration. We found that plasma sEGFR was significantly decreased in the NSCLC patient group as compared to the control group (median value: 48.6 vs. 55.6 ng/mL respectively; p = 0.0002). Moreover, we demonstrated that sEGFR inhibits growth and migration of NSCLC cells in vitro through molecular mechanisms that included perturbation of EGF/EGFR cell signaling and holoreceptor internalization. These data show that sEGFR is a potential circulating biomarker with a physiological protective role, providing a first approach to the functional role of the soluble isoform of EGFR. However, the impact of these data on daily clinical practice needs to be further investigated in larger prospective studies.

Pretreatment levels of the serum biomarkers CEA, CYFRA 21-1, SCC and the soluble EGFR and its ligands EGF, TGF-alpha, HB-EGF in the prediction of outcome in erlotinib treated non-small-cell lung cancer patients

The aim of this study has been to investigate the potential of serum biomarkers used in clinical practice (CEA, CYFRA 21-1, SCC) together with the serum epidermal growth factor receptor (EGFR) and its associated ligands (EGF, TGF-α, HB-EGF) as outcome predictors of non-small cell lung cancer (NSCLC) patients treated with the TKI erlotinib. The pretreatment levels of these markers were evaluated through immunoassays carried out in 58 patients. The progression-free survival (PFS) and overall survival (OS) were assessed by the Kaplan-Meier method and differences between groups were compared by means of the Log-Rank test. Association of risk factors with survival was evaluated using the univariate and multivariate Cox modelling procedures. Higher CEA (>5 ng/mL) and sEGFR (>56.87 ng/mL) concentrations associated significantly with a higher overall survival. The pre-treatment sEGFR serum levels constituted an independent prognostic factor. The EGFR gene mutational status and the sEGFR level combination was the single to associate significantly with longer progression-free survival periods, in circumstances in which the EGFR gene was mutated and increased protein serum levels were detected. The overall survival as assessed through a Cox analysis revealed similar death hazards with respect to low sEGFR levels combined both with non-mutated EGFR genotypes and low CEA serum levels. Our results suggest that the pre-treatment CEA and sEGFR serum levels may provide a comparable source of information to that supplied by the EGFR gene mutational status with respect to the prognosis of erlotinib treated NSCLC patients. A combined sEGFR and CEA level appraisal could be of considerable value to select patients to undergo EGFR-TKI treatments.

Circulating oncoproteins HER2/neu, EGFR and CAIX (MN) as novel cancer biomarkers

Pharmaceutical companies have developed targeted therapies such as trastuzumab and lapatinib for human epidermal growth factor receptor (HER)2/neu-positive tumors, while others have developed antiepidermal growth factor receptor (EGFR) therapies, such as tarceva and erbitux for EGFR-positive tumors. A drug called rencarex is targeted to an oncoprotein designated carbonic anhydrase IX (CAIX), which is being evaluated in renal cell carcinoma patients. Based on these targeted therapeutic approaches, this review describes clinical research studies performed with enzyme-linked immunosorbent assays specific for the circulating oncoproteins, HER2/neu, EGFR and CAIX. These circulating biomarkers have the potential to be used in conjunction with the specific targeted therapies for patient selection, monitoring and management. With the variety of new therapeutic options, the major challenge ahead will be to select the appropriate therapy or combinations of therapies for each patient. Specific biomarker tests, either alone or in panels, will be needed at the appropriate time in the course of disease to ensure that patients receive the right drug at the right time. These tests will also be valuable in monitoring the efficacy of the targeted therapies. A circulating biomarker such as serum HER2/neu may be able to specifically identify patients with progressing HER2/neu-positive disease and provide the information needed by physicians to choose from the variety of HER2/neu-targeted therapies that will soon be available to cancer patients.

Measurement of cetuximab and panitumumab-unbound serum EGFR extracellular domain using an assay based on slow off-rate modified aptamer (SOMAmer) reagents

Background

Response to cetuximab (Erbitux®) and panitumumab (Vectibix®) varies among individuals, and even those who show response ultimately gain drug resistance. One possible etiologic factor is differential interaction between the drug and target. We describe the development of an assay based on Slow Off-rate Modified Aptamer (SOMAmer^™) reagents that can distinguish drug-bound from unbound epidermal growth factor receptor (EGFR).

Methods

This quantitative assay uses a SOMAmer reagent specific for EGFR extracellular domain (ECD) as a capturing reagent. Captured SOMAmer is quantitated using PCR. Linearity and accuracy (recovery) of the assay were assessed using normal sera and purified EGFR ECD.

Results

This EGFR ECD assay showed linearity between 2.5 and 600 ng/mL. Average recovery was 101%. The assay detected EGFR but showed little cross-reactivity to other ErbB proteins: 0.4% for ErbB2, 6.9% for ErbB3, and 1.3% for ErbB4. Preincubation of normal serum with either cetuximab or panitumumab resulted in a dose-dependent decrease in EGFR ECD levels measured using the SOMAmer assay; preincubation did not affect measurement with an ELISA.

Conclusions

This SOMAmer-based serum EGFR ECD assay accurately and specifically measures EGFR in serum. Detection of significant amounts of drug-unbound EGFR in patients undergoing cetuximab or panitumumab treatment could be an indicator of poor drug response. Further studies are needed to evaluate the utility of the assay as an indicator of drug efficacy or as a guide to dosing.

The epidermal growth factor receptor conundrum

Soluble epidermal growth factor receptor (sEGFR), a cell surface and serum protein derived from an alternately spliced human EGFR transcript, is recognized by 2 therapeutic antibodies approved by the US Food and Drug Administration: cetuximab and panitumumab. Therefore, circulating sEGFR is an unanticipated first target for both of these therapeutic antibodies, adding a new level of complexity to the understanding of EGF receptor biology that should be considered in the design of future clinical studies.

Analysis of the prognostic value of soluble epidermal growth factor receptor plasma concentration in advanced non-small-cell lung cancer patients

BACKGROUND

Epidermal growth factor receptor (EGFR) is overexpressed in a variety of epithelial malignancies including lung cancer. A soluble fragment of the EGFR extracellular domain (sEGFR) can be detected in the blood of patients who have non-small-cell lung cancer (NSCLC), but its clinical/ prognostic role must be further elucidated.

METHODS

sEGFR concentration was retrospectively determined by enzyme-linked immunosorbent assay in plasma samples from 308 advanced NSCLC patients (before treatment) and 109 healthy controls and correlated with clinico-pathological variables.

RESULTS

The concentration of sEGFR was lower in NSCLC patients than in controls (P < .0001). sEGFR behaves as a sensitive but not specific screening biomarker. No significant associations were observed between sEGFR concentration and demographic/clinical characteristics such as gender, Eastern Cooperative Oncology Group performance status, stage, and number or location of the metastatic sites. sEGFR was lower in patients with progressive disease or in squamous cell carcinoma compared with adenocarcinoma, but these differences were not significant. Patients with sEGFR ≤ 34.56 ng/mL showed a shorter overall survival (median 9.1 versus 12.2 months, P = .019) than others. Moreover, in multivariate analysis, sEGFR remained a significant independent prognostic marker.

CONCLUSION

Low baseline sEGFR is associated with reduced survival in advanced NSCLC. Therefore, our findings in this large cohort of patients suggest that the determination of sEGFR concentration provides valuable prognostic information.

Phase I trial of oxaliplatin, infusional 5-fluorouracil, and leucovorin (FOLFOX4) with erlotinib and bevacizumab in colorectal cancer

RATIONALE

This phase I study was conducted to determine the maximum tolerated dose (MTD) of erlotinib, an oral epidermal growth factor receptor tyrosine kinase inhibitor, with 5-fluorouracil/leucovorin/oxaliplatin (FOLFOX4) in patients with advanced colorectal cancer (CRC). Bevacizumab was later included as standard of care at the MTD.

PATIENTS AND METHODS

Patients received FOLFOX4 with escalating doses of erlotinib: dose level (DL) 1, 50 mg; DL 2, 100 mg; and DL 3, 150 mg once daily continuously. Bevacizumab 5 mg/kg days 1 and 15 was added at the MTD upon Food and Drug Administration approval. Correlative studies included pharmacokinetics, pharmacodynamics was assessed in paired skin biopsies, and fluorodeoxyglucose positron emission tomography scans.

RESULTS

Fifteen patients received 60 cycles (120 FOLFOX treatments). Two dose-limiting toxicities (DLTs) were seen at DL 3: intolerable grade 2 rash (Common Terminology Criteria for Adverse Events version 2) lasting > 1 week, and grade 4 neutropenia. Dose level 2 was expanded to 6 more patients, this time adding bevacizumab, and 1 DLT of grade 3 mucositis occurred. As expected, the primary toxicities were cytopenias, diarrhea, rash, and fatigue. There were 2 occurrences of pneumatosis. One patient experienced an unrelated grade 4 myocardial infarction before starting chemotherapy. No pharmacokinetic drug interactions were observed. The Response Evaluation Criteria in Solid Tumors response rate was 11 of 14 (78%), median progression-free survival was 9.5 months, and median overall survival was 30 months. Three patients are currently alive > 3 years, with 1 having no evidence of disease.

CONCLUSION

The MTD of erlotinib with FOLFOX4 with or without bevacizumab is 100 mg daily. The regimen appeared to increase toxicity but showed activity in patients with CRC.

Soluble epidermal growth factor receptor (sEGFR) and carcinoembryonic antigen (CEA) concentration in patients with non-small cell lung cancer: correlation with survival after erlotinib and gefitinib treatment

BACKGROUND

In patients with non-small cell lung cancer (NSCLC), a higher response rate can be achieved with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) when selection for therapy is guided by mutation analysis or gene amplification. However, both tests are complex and require tumour tissue. Simple methods to identify responders prior to EGFR-TKI treatment are urgently needed. This study aimed to define the relation between serum sEGFR levels, carcinoembryonic antigen (CEA) and survival in NSCLC patients treated with EGFR-TKIs.

METHODS

Patients with stage III/IV NSCLC treated with gefitinib or erlotinib between July 2002 and December 2005 were reviewed. Levels of serum soluble EGFR (sEGFR) were determined by a sandwich quantitative enzyme-linked immunosorbent assay. A chemiluminescence immunoassay was used for CEA. The relation between sEGFR and survival was investigated.

RESULTS

One hundred and two NSCLC patients, mainly stage IV (80%), were identified. Mean sEGFR at baseline was 55.9 μg/l (range 35.3-74.5 μg/l). The median CEA level was 11.1 μg/l (range <1.0-2938.0 μg/l). Median overall survival was 5.2 months (range 1-52 months). Decreasing log CEA values (HR 1.51, 95% CI 1.11-2.04, multivariate analysis) and increasing sEGFR values (HR 0.96, 95% CI 0.93-0.99, multivariate analysis) were both independently associated with prolonged survival. Higher levels of pre-treatment sEGFR were associated with lower risk of progressive disease within three months (p=0.04).

CONCLUSIONS

Both baseline sEGFR and CEA levels in NSCLC patients receiving EGFR-TKIs showed a significant correlation with survival. To distinguish whether these factors have a predictive or a prognostic value, validation is warranted in an independent patient series containing a control arm without EGFR-TKI treatment.

[American Society of Clinical Oncology Clinical Practice Guideline update on chemotherapy for stage IV non-small-cell lung cancer]

本文旨在为Ⅳ期非小细胞肺癌患者的治疗提供更新版推荐。本文资料检索源自2002年以来公布的相关随机试验文献。此指南范围限于化疗与生物治疗。更新委员会对这些文献进行了总结并提供了推荐更新。162篇文献符合标准被纳入参考。本推荐基于可改善总生存期的治疗方法。仅改善无进展生存期的治疗方法推动了对毒性及生存质量的监测。对于体力状态评分为0分或1分患者的一线治疗，可推荐以铂类为基础的细胞毒性药物的两药联用。对铂类治疗有禁忌的患者，可采用非铂类细胞毒性两药联合。对于体力状态评分为2分的患者，单一细胞毒性药物即可。对于疾病进展或经过4个周期的治疗仍对治疗无反应的患者，应停止一线细胞毒性化疗。即使在6个周期后患者对治疗仍有反应，亦应停止两药细胞毒性化疗。对于伴有明确的表皮生长因子受体（epidermal growth factor receptor, EGFR）突变的患者，可推荐一线采用吉非替尼治疗；对于EGFR突变为阴性或不明确的患者，细胞毒性化疗更佳。除具有特定临床特征的患者外，可推荐贝伐单抗与卡铂-紫杉醇联用。对于通过免疫组化证实EGFR阳性的肿瘤患者，可推荐西妥昔单抗与顺铂-长春瑞滨联用。多西紫杉醇、厄洛替尼、吉非替尼或培美曲塞被推荐作为二线治疗。对于未曾接受过厄洛替尼或吉非替尼治疗的患者，可推荐厄洛替尼作为三线治疗。现有数据不足以推荐常规三线采用细胞毒性药物。已有的证据也不足以推荐常规应用分子标记物选择化疗。

EGFR isoforms and gene regulation in human endometrial cancer cells

Background

Epidermal growth factor (EGF) and its receptor (EGFR) constitute a principal growth-promoting pathway in endometrial cancer cells. Pre-clinical studies were undertaken to compare the expression of EGFR isoforms and the downstream effects of activating or blocking EGFR function in Ishikawa H cells, derived from a moderately differentiated type I endometrioid adenocarcinoma, or in Hec50co cells, derived from a poorly differentiated type II adenocarcinoma with papillary serous sub-differentiation.

Results

We investigated whether EGFR mutations are present in the tyrosine kinase domain (exons 18-22) of EGFR and also whether EGFR isoforms are expressed in the Ishikawa H or Hec50co cell lines. Sequence of the EGFR tyrosine kinase domain proved to be wild type in both cell lines. While both cell lines expressed full-length EGFR (isoform A), EGFR and sEGFR (isoform D) were expressed at significantly lower levels in Hec50co cells compared to Ishikawa H cells. Analysis of gene expression following EGF vs. gefitinib treatment (a small molecule EGFR tyrosine kinase inhibitor) was performed. Early growth response 1, sphingosine kinase 2, dual specificity phosphatase 6, and glucocorticoid receptor DNA binding factor 1 are members of a cluster of genes downstream of EGFR that are differentially regulated by treatment with EGF compared to gefitinib in Ishikawa H cells, but not in Hec50co cells.

Conclusions

Type I Ishikawa H and type II Hec50co endometrial carcinoma cells both express EGFR and sEGFR, but differ markedly in their responsiveness to the EGFR inhibitor gefitinib. This difference is paralleled by differences in the expression of sEGFR and EGFR, as well as in their transcriptional response following treatment with either EGF or gefitinib. The small cluster of differently regulated genes reported here in these type I vs. type II endometrial cancer-derived cell lines may identify candidate biomarkers useful for predicting sensitivity to EGFR blockade.

American Society of Clinical Oncology Clinical Practice Guideline update on chemotherapy for stage IV non-small-cell lung cancer

The purpose of this article is to provide updated recommendations for the treatment of patients with stage IV non-small-cell lung cancer. A literature search identified relevant randomized trials published since 2002. The scope of the guideline was narrowed to chemotherapy and biologic therapy. An Update Committee reviewed the literature and made updated recommendations. One hundred sixty-two publications met the inclusion criteria. Recommendations were based on treatment strategies that improve overall survival. Treatments that improve only progression-free survival prompted scrutiny of toxicity and quality of life. For first-line therapy in patients with performance status of 0 or 1, a platinum-based two-drug combination of cytotoxic drugs is recommended. Nonplatinum cytotoxic doublets are acceptable for patients with contraindications to platinum therapy. For patients with performance status of 2, a single cytotoxic drug is sufficient. Stop first-line cytotoxic chemotherapy at disease progression or after four cycles in patients who are not responding to treatment. Stop two-drug cytotoxic chemotherapy at six cycles even in patients who are responding to therapy. The first-line use of gefitinib may be recommended for patients with known epidermal growth factor receptor (EGFR) mutation; for negative or unknown EGFR mutation status, cytotoxic chemotherapy is preferred. Bevacizumab is recommended with carboplatin-paclitaxel, except for patients with certain clinical characteristics. Cetuximab is recommended with cisplatin-vinorelbine for patients with EGFR-positive tumors by immunohistochemistry. Docetaxel, erlotinib, gefitinib, or pemetrexed is recommended as second-line therapy. Erlotinib is recommended as third-line therapy for patients who have not received prior erlotinib or gefitinib. Data are insufficient to recommend the routine third-line use of cytotoxic drugs. Data are insufficient to recommend routine use of molecular markers to select chemotherapy.

Proteomic profile of differentially expressed plasma proteins from dystrophic mice and following suberoylanilide hydroxamic acid treatment

PURPOSE

Histone Deacetylase Inhibitors (DI) ameliorates dystrophic muscle regeneration restoring muscular strength in the mdx mouse model of Duchenne muscular dystrophy (DMD). The further development of these compounds as drugs for DMD treatment is currently hampered by the lack of knowledge about DIs effect in large dystrophic animal models and that of suitable biomarkers to monitor their efficacy.

EXPERIMENTAL DESIGN

In this study we applied proteomic analysis to identify differentially expressed proteins present in plasma samples from mdx mice treated with the Suberoylanilide hydroxamic acid (SAHA) and relative normal controls (WT).

RESULTS

Several differentially expressed proteins were identified between untreated wild type and mdx mice. Among these, fibrinogen, epidermal growth factor 2 receptor, major urinary protein and glutathione peroxidase 3 (GPX3) were constitutively up-regulated in mdx, while complement C3, complement C6, gelsolin, leukaemia inhibitory factor receptor (LIFr), and alpha 2 macroglobulin were down-regulated compared to WT mice. SAHA determined the normalization of LIFr and GPX3 protein level while apoliprotein E was de novo up-regulated in comparison to vehicle-treated mdx mice.

CONCLUSIONS AND CLINICAL RELEVANCE

Collectively, these data unravel potential serological disease biomarkers of mdx that could be useful to monitor muscular dystrophy response to DI treatment.

EGFR ligands and their signaling scissors, ADAMs, as new molecular targets for anticancer treatments

Members of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases and their ligands (EGFR ligands) are known to play crucial roles in the regulation of cell proliferation and differentiation, and in the survival of many types of cancer. HER family members are activated in cancer cells and are now considered to be useful molecular targets for cancer therapy. Recently, several new drugs, including monoclonal antibodies and small-molecule inhibitors that target HER members, have been developed and clinically used to treat solid tumors. Members of a disintegrin and metalloproteinase (ADAM) family are thought to mediate the shedding of EGFR ligands and this event is critical for the production of soluble functional EGFR ligands. In melanoma cells, UV irradiation activates some ADAM members and induces melanoma cell growth through EGFR ligand shedding by activated ADAMs. These findings suggest that ADAM inhibitors are also candidate anticancer drugs acting via the blockade of HER family signaling pathways. After shedding of EGFR ligands by ADAMs, the carboxy-terminal fragments (CTFs) of EGFR ligands in the cytoplasm are translocated to the nucleus and induce cell proliferation by binding and exporting repressors and activating cyclin A and c-Myc. Based on these findings, the present molecular targeting therapy against HER members, EGFR and HER2, may not be sufficient, while ADAMs and nuclear translocation of the CTF of EGFR ligands are potential targets for the treatment of cancer, particularly malignancies that are dependent on the EGF family.

Epidermal growth factor receptor serum (sEGFR) level may predict response in patients with EGFR-positive advanced colorectal cancer treated with gefitinib?

PURPOSE

Epidermal growth factor receptor-overexpression reported in colorectal cancer, justifies therapeutic use of EGFR-inhibitors. We have recently conducted a phase II study in 57 patients with EGFR-positive advanced colorectal cancer (ACC) who received gefitinib-FOLFOX6 followed by gefitinib-single agent as maintenance. Main biological objective was to assess sEGFR as surrogate marker of tyrosine kinase inhibition and as predictor of response.

METHODS

sEGFR, evaluated by quantitative ELISA, was investigated as predictive factor both taking into account the basal value only, and its whole pattern over time. sEGFR was collected at baseline and at every 2-months assessment in 42 cases. Thirty-three patients reported CR/PR as best objective response (BOR), while nine showed SD/PD.

RESULTS

Retrospectively, on average, the sEGFR values reported by both responders (CR/PR) and not responders (SD/PD) were already different at baseline (49.4 +/- 6.2 and 42.4 +/- 8.4 ng/ml respectively). This difference was statistically significant (p = 0.042). Although sEGFR trend over time confirmed the basal difference (p = 0.032), this result should be taken with caution, due to the small number of patients reporting EGFR values besides the basal one.

CONCLUSIONS

Higher sEGFR at baseline was associated to BOR and may be considered a significant predictor of outcome in patients with ACC.

Anti-angiogenic potential of CoenzymeQ10, riboflavin and niacin in breast cancer patients undergoing tamoxifen therapy

Tumour angiogenesis is a complex mechanism consisting of multi-step events including secretion or activation of angiogenic factors by tumour cells, activation of proteolytic enzymes, proliferation, migration and differentiation of endothelial cells. Both primary and metastatic tumours in the breast are dependent on angiogenesis. In the present study, 84 breast cancer patients were randomized to receive a daily supplement of CoQ(10) 100 mg, riboflavin 10 mg and niacin 50 mg (CoRN), one dosage per day along with tamoxifen (TAM) 10 mg twice a day. Serum pro-angiogenic levels were elevated in untreated breast cancer patients (Group II) and their levels were found to be reduced in breast cancer patients undergoing TAM therapy for more than 1 year (Group III). When these group III breast cancer patients were supplemented with CoRN for 45 days (Group IV) and 90 days (Group V) along with TAM, a further significant reduction in pro-angiogenic marker levels were observed. Supplementing CoRN to breast cancer patients has found to decrease the levels of pro-angiogenic factors and increase the levels of anti-angiogenic factors. A reduction in pro-angiogenic marker levels attributes to reduction in tumour burden and may suggest good prognosis and efficacy of the treatment, and might even offer protection from cancer metastases and recurrence.

Institutional guidelines and ongoing studies in management of liver tumours: the experience of the European Institute of Oncology

BACKGROUND

An institutional task force on upper gastrointestinal tumours is active at the European Institute of Oncology (EIO). Members decided to collate the institutional guidelines on management of liver tumours (primary and metastatic) into a document. This article is aimed at presenting the current treatment guidelines as well as ongoing research protocols and trials in this field at the EIO.

METHODS

A steering committee convened to assign tasks to individual members. Contributions from experts in each treatment area were collated in a single document, in order to produce a draft for subsequent review from the aforementioned committee. Six drafts have been discussed and the final version approved.

RESULTS

Surgical, medical oncology, interventional radiology, nuclear medicine and radiation therapy approaches, their roles in management of liver tumours and ongoing research trials are presented and discussed in this article.

CONCLUSIONS

At the EIO a multi-disciplinary integrated approach to liver tumours is standard and several ongoing research projects are currently active in this field.

Gefitinib combined with endocrine manipulation in patients with hormone-refractory prostate cancer: quality of life and surrogate markers of activity

We investigated efficacy of gefitinib in hormone-refractory prostate cancer. Between March 2003 and December 2004, 23 patients with hormone-refractory prostate cancer were assigned to receive 250 mg oral gefitinib daily in addition to antiandrogen and luteinizing hormone-releasing hormone analogue for at least 2 months or until disease progression. Patients with progression stopped antiandrogen therapy, and received gefitinib and the luteinizing hormone-releasing hormone analogue. Serum HER2 and epidermal growth factor receptor extracellular domain were evaluated every 2 months. Gefitinib treatment did not result in any objective measurable response or responses in prostate-specific antigen. Median time to progression was 70 days (33-336). Median overall survival was 293 days (25-75 percentile: 235-349). HER2 extracellular domain mean value was 9.6 ng/ml (range 6.9-13.3) at basal time and was 10.1 (range 6.0-14.1) after 2 months. Epidermal growth factor receptor mean basal value was 51.0 ng/ml (range 41.4-75.3). After 2 months of treatment the mean value was 51.1 ng/ml (range 41.5-61.4). One patient had reduction in the pain score from baseline without an increase in the analgesic score. Four patients (17%) out of 23 had pain progression with an increase from baseline of at least 25% in the analgesic score. The study was discontinued before target accrual was reached owing to lack of efficacy of the drug. Our results do not support the efficacy of gefitinib in combination with endocrine treatment for hormone-refractory prostate cancer.

Analysis of biologic surrogate markers from a Children's Oncology Group Phase I trial of gefitinib in pediatric patients with solid tumors

This trial evaluated the effect of gefitinib on the plasma circulating levels of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP)-2 and -9 of patients treated on a pediatric Phase I trial. Complete plasma correlative studies were obtained from 16 of the 25 enrolled patients. There was a trend for lower MMP-2 baseline levels in patients with partial response or stable disease. The Ewing sarcoma from the only patient with partial response lacked egfr mutations. Gefitinib did not induce any significant variation in the levels of the assessed parameters, and none of these determinations showed significant predictive or prognostic value.

Germline polymorphisms in EGFR and survival in patients with lung cancer receiving gefitinib

The purpose of this study was to evaluate associations between germline epidermal growth factor receptor (EGFR) variants involved in transcriptional regulation and overall survival in white patients with non-small-cell lung cancer (NSCLC) treated with the EGFR tyrosine kinase inhibitor, gefitinib. Of 175 consecutive patients treated with oral gefitinib (250 mg/day), 170 (median age: 67 years; 72% men) were evaluable for genotyping and survival. Fifty-five patients (33%) had stable disease and 17 (10%) had an objective response. The most common of four haplotypes was G-C (EGFR*1) at the EGFR -216G>T and -191C>A loci (frequency, 0.45). After adjusting for performance status, previous platinum-containing chemotherapy and occurrence of skin rash or diarrhea during the first treatment cycle in patients with performance status 0 or 1 (N=139), the absence of EGFR*1 was associated with significantly better survival (hazard ratio: 0.54; 95% confidence interval: 0.32-0.91; P=0.015). The results may help identify patients with NSCLC who can benefit from gefitinib treatment.

Pharmacogenetics of ABCG2 and adverse reactions to gefitinib

Gefitinib is an inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase with activity in non-small-cell lung cancer. Diarrhea and skin toxicity are prominent gefitinib-related adverse events that potentially limit its use. Gefitinib is a substrate for ABCG2 (ABCP, BCRP, MXR), a polymorphic efflux transporter protein that is highly expressed in the intestines and liver. Here we investigated associations between allelic variants of EGFR, ABCG2, and the transporter protein ABCB1 with diarrhea and skin toxicity in gefitinib-treated patients. One variant, a common functional single-nucleotide polymorphism (SNP) in the ABCG2 gene, was associated with diarrhea in 124 patients treated with oral gefitinib 250 mg once daily; seven (44%) of 16 patients heterozygous for ABCG2 421C>A (Q141K) developed diarrhea, versus only 13 (12%) of 108 patients homozygous for the wild-type sequence (P = .0046). However, this SNP was not associated with skin toxicity (P = .99). The finding suggests that patients with reduced ABCG2 activity due to a common genetic variant are at increased risk for substrate drug-induced diarrhea, with implications for optimizing treatment with such agents.

Heterodimerization of insulin-like growth factor receptor/epidermal growth factor receptor and induction of survivin expression counteract the antitumor action of erlotinib

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been used to treat non-small cell lung cancer (NSCLC). However, the overall response rate to EGFR TKIs is limited, and the mechanisms mediating resistance to the drugs are poorly understood. Here, we report that insulin-like growth factor-I receptor (IGF-IR) activation interferes with the antitumor activity of erlotinib, an EGFR TKI. Treatment with erlotinib increased the levels of EGFR/IGF-IR heterodimer localized on cell membrane, activated IGF-IR and its downstream signaling mediators, and stimulated mammalian target of rapamycin (mTOR)-mediated de novo protein synthesis of EGFR and survivin in NSCLC cells. Inhibition of IGF-IR activation, suppression of mTOR-mediated protein synthesis, or knockdown of survivin expression abolished resistance to erlotinib and induced apoptosis in NSCLC cells in vitro and in vivo. Our data suggest that enhanced synthesis of survivin protein mediated by the IGFR/EGFR heterodimer counteracts the antitumor action of erlotinib, indicating the needs of integration of IGF-IR-targeted agents to the treatment regimens with EGFR TKI for patients with lung cancer.

Pharmacogenomics of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors

The EGFR is a validated anticancer target whose successful exploitation has added novel agents to our current treatment protocols. Subsets of patients have shown to benefit the most from these therapies, and though these differential responses have yet to be completely defined, they are mostly of genetic nature. Egfr amplifications have shown to increase sensitivity to both small molecule inhibitors and specific monoclonal antibodies targeting the EGFR. A somatic/germline egfr intron 1 CA repeat sequence polymorphism has shown to have an important role in the control of EGFR protein expression, and has been linked to an increased risk of familial breast cancer, a worse outcome in patients with colorectal cancer, and anti-EGFR treatment efficacy in preclinical models. Egfr activating mutations have been recently described in lung cancer linking a cluster of genotypes with sensitivity to EGFR tyrosine kinase pharmacological inhibition. Despite the initial excitement that this discovery elicited, follow-up reports have not unequivocally confirmed this finding, and these drugs have been solidly efficacious both in individual patients and in diseases generally lacking egfr mutations such as pancreas cancer. We are witnessing exciting developments in the field of the pharmacogenomics of cancer, and this has particularly evolved in the area pertaining EGFR tyrosine kinase inhibitors. This review will discuss the background and currently available preclinical and clinical data.

Serum epidermal growth factor receptor/HER-2 predicts poor survival in patients with metastatic breast cancer

BACKGROUND

Epidermal growth factor receptor (EGFR, HER-1, and erbB1) is overexpressed in primary breast cancer and had been identified as a poor prognostic factor.

METHODS

Pretreatment serum EGFR levels were quantified by using an enzyme-linked immunoadsorbent assay in a Phase III first-line trial of letrozole and tamoxifen and were correlated with patient outcomes.

RESULTS

Serum EGFR levels in a control group of 117 healthy, postmenopausal women measured 64.1 +/- 13.3 ng/mL (mean +/- standard deviation). Using a cutoff EGFR level of 44.1 ng/mL from the control group (5% nonparametric method), 53 of 535 patients (10%) had decreased serum levels of EGFR. Patients with decreased serum EGFR had no significant difference in objective response rate (ORR), clinical benefit rate (CBR), time to progression (TTP), or time to treatment failure (TTF); however, they did have significantly reduced survival compared with patients who had normal serum EGFR levels (median survival, 23.3 months vs. 30.9 months; P = .007). A combined analysis of pretreatment serum EGFR and HER-2 yielded no additional predictive information for ORR, CBR, TTP, or TTF compared to serum HER-2 alone. However, in the current analysis, a subgroup of patients who had decreased serum EGFR and normal serum HER-2 was identified (n = 39 of 535 patients; 7.3%) that had significantly reduced survival compared with patients who had normal serum levels of both EGFR and HER-2 (median survival, 23.5 months vs. 37.1 months; P = .005). In multivariate analysis, a decreased serum EGFR level remained a significant independent prognostic factor for decreased survival (hazards ratio, 1.58; P = .007).

CONCLUSIONS

In patients who had metastatic breast cancer, decreased serum EGFR/normal serum HER-2 predicted shorter survival compared with patients who had normal levels of serum EGFR/HER-2. This patient subgroup deserves further study to assess their response to and selection for anti-EGFR-directed therapies.

Serum EGFR levels and efficacy of trastuzumab-based therapy in patients with metastatic breast cancer

The antibody trastuzumab inhibits signal transduction in Her-2/neu overexpressing human breast cancer. However, the activation of co-expressed EGFR has also been show to additionally modulate the anti-tumoural effects of this drug. Similar to Her-2/neu, the extra cellular binding region of EGFR is believed to be proteolytically released from the cell surface upon receptor activation and can be detected in patients' serum (sEGFR). Considering the biological significance of an interaction between EGFR and Her-2/neu signalling in other human malignancies, we have investigated if trastuzumab treatment would affect sEGFR in 33 patients with Her-2/neu overexpressing metastatic breast cancer. We detected EGFR expression in 33% of Her-2/neu overexpressing breast tumours. In contrast to serum Her-2/neu (ECD) levels, which were correlated with the degree of Her-2/neu expression (P=0.048, Mann-Whitney test), we did not detect significant differences between sEGFR serum levels in EGFR expressing or non-expressing tumours. Furthermore, sEGFR serum levels were not correlated with clinical parameters such as response or clinical benefit rates, and no association was found between increased sEGFR levels and progression-free survival or overall survival. While we have previously observed a selective and significant decrease of ECD levels in patients who derived a clinical benefit from trastuzumab treatment during the first weeks of treatment, we were unable to find similar alterations in sEGFR concentrations. We therefore conclude that the measurement of systemic sEGFR levels in addition to ECD serum concentrations do not allow the prediction of clinical course of trastuzumab-treated patients more accurately.

Survival impact of epidermal growth factor receptor overexpression in patients with non-small cell lung cancer: a meta-analysis

BACKGROUND

It is thought that overexpression of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) might compromise patient survival, presumably by promoting tumour growth by an autocrine mechanism. However, conflicting results have been reported from various laboratories, and the clinical importance of EGFR overexpression remains unsettled.

METHODS

A meta-analysis of previous studies was performed to quantitatively review the effects of EGFR overexpression on survival in patients with NSCLC using a DerSimonian-Laird random effects model. Eighteen studies including 2972 patients were subjected to final analysis.

RESULTS

Overall, positivity for EGFR overexpression differed between histological types: 39% in adenocarcinomas, 58% in squamous cell carcinomas, 38% in large cell carcinomas, and 32% in cancers in a miscellaneous category (p<0.0001). The combined hazard ratio (HR) was 1.14 (95% CI 0.97 to 1.34; p = 0.103), indicating that EGFR overexpression has no significant impact on survival. When only the 15 immunohistochemistry based studies were considered, the combined HR was 1.08 (95% CI 0.92 to 1.28; p = 0.356), again suggesting that EGFR overexpression has no impact on survival. Heterogeneity testing indicated that there was heterogeneity between studies but publication bias was absent, which suggests that the summary statistics obtained may approximate the actual average.

CONCLUSIONS

EGFR overexpression was not associated with poorer survival in patients with NSCLC. Specific mutations of the EGFR gene will need further study in terms of survival implications.

Current Status of Small-Molecule Tyrosine Kinase Inhibitors Targeting Epidermal Growth Factor Receptor in Colorectal Cancer

The epidermal growth factor receptor (EGFR) is expressed in the majority of colorectal cancers (CRCs) and is associated with poor clinical outcome. Ample evidence suggests that inhibition of this pathway by monoclonal antibodies directed against EGFR leads to antitumor activity in CRC. Small-molecule tyrosine kinase inhibitors (TKIs) provide distinct advantages over monoclonal antibodies by virtue of lower production costs, ease of oral administration, and ability to target multiple cellular survival pathways. Despite theoretical advantages, multiple early-phase trials of EGFR TKIs fail to demonstrate single-agent activity in CRC. However, the unusually high response rates observed when gefitinib, an EGFR TKI, is combined with chemotherapy for patients with metastatic CRC suggest a possible synergistic effect. This effect is not seen in non-small-cell lung cancer (NSCLC), for which larger phase III trials have been conducted. The differences between NSCLC and CRC with respect to EGFR expression and mutation status do not completely explain this dichotomy, and further investigation into the pharmacogenomics of EGFR tyrosine kinase inhibition in CRC is under way. Significant effort is directed toward newer strategies targeted at the EGFR in CRC. A new generation of small-molecule TKIs is emerging in which multiple receptor pathways, including ErbB2 and vascular endothelial growth factor receptor, can be simultaneously targeted with EGFR. These agents are still in early-phase clinical trials, and specific data for patients with CRC are forthcoming.

Promises and pitfalls in the prediction of antiepidermal growth factor receptor activity

There is a constant examination of the features that may anticipate or predict the likelihood of the clinical benefit that a patient may experience from a given therapy. This is especially true in the case of novel targeted therapies, as proof-of-principle experimental or pilot analyses are increasingly being embedded into clinical protocols. An unprecedented number of significant developments in the field of epidermal growth factor receptor-targeted therapy have occurred in recent months. This is exemplified by the discovery of activating mutations in the catalytic domain of the epidermal growth factor receptor that increase sensitivity to antiepidermal growth factor receptor small-molecule inhibitors. This review discusses the recent advances and controversies of the different approaches to predict the efficacy of antiepidermal growth factor receptor agents and the effectiveness of the tools that we are using to evaluate and predict the efficacy of epidermal growth factor receptor-targeted drugs and their potential pitfalls.

Epidermal growth factor receptor dynamics influences response to epidermal growth factor receptor targeted agents

Analysis of gene expression of cancer cell lines exposed to erlotinib, a small molecule inhibitor of the epidermal growth factor receptor (EGFR), showed a marked increase in EGFR mRNA in resistant cell lines but not in susceptible ones. Because cetuximab induces EGFR down-regulation, we explored the hypothesis that treatment with cetuximab would interfere with erlotinib-induced EGFR up-regulation and result in antitumor effects. Exposure of the resistant biliary tract cancer cell line HuCCT1 but not the susceptible A431 epidermoid cell line to erlotinib induced EGFR mRNA and protein expression. Combined treatment with cetuximab blunted the erlotinib-induced EGFR up-regulation and resulted in inhibition of cell proliferation and apoptosis in the HuCCT1 cells. Blockage of erlotinib-induced EGFR synthesis in HuCCT1 cells by small interfering RNA resulted in identical antitumor effects as cetuximab, providing mechanistic specificity. In mice xenografted with A431, HuCCT1, and the pancreatic cancer cell line Panc430, maximal growth arrest and decrease in Ki67 proliferation index were documented with combined therapy, and EGFR down-regulation was observed in cetuximab-treated tumors. These results may indicate that resistance to EGFR kinase inhibition may be, at least in part, mediated by a highly dynamic feedback loop consisting of up-regulation of the EGFR upon exposure to EGFR kinase inhibitors. Abrogation of this response by small interfering RNA-mediated EGFR mRNA down-regulation and/or by cetuximab-mediated protein clearance induced tumor arrest across several cancer models with different EGFR expression levels, suggesting that resistance and sensitivity are dynamic events where proportional decrease in the target rather than absolute content dictates outcome.

Predictors of Sensitivity and Resistance to Epidermal Growth Factor Receptor Inhibitors

Lung cancer is one of the leading types of cancer with an associated high mortality. Currently, treatment with conventional cytotoxic agents remains suboptimal. Inhibition of the epidermal growth factor receptor (EGFR) with monoclonal antibodies or small-molecule inhibitors of the tyrosine kinase (TK) domain of the receptor have demonstrated modest, albeit significant, antitumor activities in patients with non-small-cell lung cancer (NSCLC). The goal of any targeted therapy is to direct treatment to those patients who are more likely to derive benefit from such a treatment. Two interventions may improve the predicted sensitivity to these agents: (1) the use of a real predictor before treatment, represented by pharmacodiagnostic tests, and (2) studying the relationship between an early event after treatment and outcome, represented by pharmacodynamic tests. Pharmacodiagnostic factors that have been studied include the clinical features and histologic subtype of the tumor, the presence of somatic mutations in the TK domain of the EGFR, the expression of the receptor itself, and the activation of the receptor signaling pathway. Pharmacodynamic events associated with improved outcome include drug-induced rash and regulation of the receptor expression. Currently, the best established determinant of response to small-molecule inhibitors of the EGFR is the presence of activating mutations in the receptor TK domain. However, it is not known whether these functional mutations are involved in the response of NSCLC to monoclonal antibodies. Further investigation is needed to better predict patients who are more likely to benefit from these drugs.