Targeting the epidermal growth factor receptor

Mutation in the tyrosine kinase domain of epidermal growth factor receptor is a predictive and prognostic factor for gefitinib treatment in patients with non-small cell lung cancer

PURPOSE

Mutations in epidermal growth factor receptor (EGFR) can be used to predict the tumor response of patients receiving gefitinib for non-small cell lung cancer (NSCLC). We investigated the association between mutations in EGFR tyrosine kinase domain and tumor response and survival in gefitinib-treated NSCLC patients.

EXPERIMENTAL DESIGN

EGFR mutations in exons 18 to 21 were analyzed by DNA sequencing of paraffin-embedded tumor tissues from gefitinib-treated NSCLC patients. The results were correlated with clinical variables.

RESULTS

EGFR mutations were found in 61.1% (33 of 54) of cases; response rate and disease control rate were 56.8% and 68.5%, respectively. There was no significant difference in mutation rates between adenocarcinoma (29 of 43) and nonadenocarcinoma (4 of 11; P = 0.085). However, all four nonadenocarcinomas with EGFR mutations had no response to gefitinib. Presence of EGFR mutations was the only independent predictor for disease control (P = 0.003) and tumor response (P = 0.017) in multivariate analysis; positive predictive values were 87.9% and 70.8% and negative predictive values were 61.9% and 69.2%, respectively. In comparison with patients whose tumor was negative for EGFR mutations, patients with EGFR mutations had better progression-free survival (median, 7.6 versus 1.7 months; P = 0.011) and overall survival (median, 14.7 versus 4.7 months; P = 0.046).

CONCLUSIONS

Mutations in EGFR tyrosine kinase correlate with treatment response and survival in gefitinib-treated NSCLC patients and can be used as a predictive and prognostic factor. Thus, analysis of EGFR tyrosine kinase mutations in lung adenocarcinoma is of clinical significance, as it can permit the customization of treatment with EGFR tyrosine kinase inhibitors.

A study of cytotoxic synergy of UCN-01 and flavopiridol in syngeneic pair of cell lines

Flavopiridol and UCN-01 are two novel protein kinase inhibitors with diverse cellular effects that may complement each other with regards to induction of apoptosis. HeLa cells engineered to overexpress human survivin (HeLa-S) were at least approximately 4.8-fold resistant to UCN-01 relative to proliferation observed in control HeLa cells (HeLa-V). Flavopiridol cytotoxicity as measured using the MTT assay was unaffected in HeLa-S cells when compared with HeLa-V cells. Similarly, simultaneous treatment of HeLa-V cells with flavopiridol and UCN-01 for 72 hours did not result in synergistic inhibition of proliferation; however, in HeLa-S cells, this combination resulted in synergistic inhibition of cell proliferation. Flavopiridol and UCN-01 augmented apoptosis in HeLa-S cells (as compared with HeLa-V cells) as measured by caspase-3 cellular activity assay, DNA fragmentation and PARP cleavage by western blot. In HeLa-V and -S cells, combination treatment resulted in caspase-8 cleavage. Caspase-9 was expressed in HeLa-V cells; however, there was a marked reduction of caspase-9 content in HeLa-S cells only. Combination treatment resulted in a significant reduction in survivin abundance in HeLa-S and SKBR3-UR cells, but not in their respective parental lines. The synergy of Flavopiridol and UCN-01 are selectively toxic to survivin-overexpressing cell lines and the mechanism of toxicity involves caspase-dependent cell death.

Epidermal growth factor receptor inhibitors and their role in non-small-cell lung cancer

The epidermal growth factor receptor (EGFR) is a promising target in the treatment of advanced stage non-small-cell lung cancer (NSCLC). Currently erlotinib and gefitinib are approved by the US Food and Drug Administration, whereas cetuximab is being studied for use in NSCLC. Erlotinib has shown a survival advantage in patients with advanced NSCLC. Further studies have identified female sex, nonsmokers, Asian race, good performance status, and adenocarcinoma histology as predictors of patient response to these agents. A genetic mutation in EGFR has also been correlated with an increase in response.

Molecular determinants of cetuximab efficacy

PURPOSE

To investigate whether mRNA expression levels of cyclin D1 (CCND1), cyclooxygenase 2 (Cox-2), epidermal growth factor receptor (EGFR), interleukin 8 (IL-8), and vascular endothelial growth factor (VEGF), all members of the EGFR signaling pathway, are associated with clinical outcome in patients with EGFR-expressing metastatic colorectal cancer (CRC) treated with cetuximab.

PATIENTS AND METHODS

Thirty-nine patients with metastatic CRC, refractory to both irinotecan and oxaliplatin, were enrolled on IMCL-0144 and treated with single-agent cetuximab. The intratumoral mRNA levels of CCND1, Cox-2, EGFR, IL-8, and VEGF were assessed from paraffin-embedded tissue samples using laser-capture microdissection and quantitative real-time polymerase chain reaction.

RESULTS

There were 21 women and 18 men with a median age of 64 years (range, 35 to 83 years). Higher gene expression levels of VEGF were associated with resistance to cetuximab (P = .038; Kruskal-Wallis test). The combination of low gene expression levels of Cox-2, EGFR, and IL-8 was significantly associated with overall survival (13.5 v 2.3 months; P = .028; log-rank test). Both findings were independent of skin toxicity that was itself significantly correlated to survival. Patients with a lower mRNA amount of EGFR had a longer overall survival compared with patients that had a higher mRNA amount (7.3 v 2.2 months; P = .09; log-rank test). Patients with lower expression of Cox-2 had a significantly higher rate of grade 2 to 3 skin reactions under cetuximab treatment.

CONCLUSION

This pilot study suggests that gene expression levels of Cox-2, EGFR, IL-8, and VEGF in patients with metastatic CRC may be useful markers of clinical outcome in single-agent cetuximab treatment.

Molecular targets for treatment of Barrett's esophagus

SUMMARY. Esophageal cancer is one of the most deadly forms of gastrointestinal cancer with a mortality rate exceeding 90%. The major risk factors for esophageal adenocarcinoma are gastroesophageal reflux disease (GERD) and its sequela, Barrett's esophagus. GERD commonly leads to esophagitis. In a minority of patients however, ongoing GERD leads to replacement of esophageal squamous mucosa with metaplastic, intestinal-type Barrett's mucosa. In the setting of continued peptic injury, Barrett's mucosa can give rise to esophageal adenocarcinoma. Despite the widespread use of potent acid suppressive therapies for patients with GERD, the incidence of esophageal adenocarcinoma, among white men in the USA, the UK and Europe has continued to rise. Cancers in Barrett's esophagus arise through a sequence of genetic events that endow the cells with six essential physiologic hallmarks of cancer as described by Hanahan and Weinberg in 2000. These cancer hallmarks include the ability to proliferate without exogenous stimulation, to resist growth-inhibitory signals, to avoid triggering the programmed death mechanism (apoptosis), to resist cell senescence, to develop new vascular supplies (angiogenesis), and to invade and metastasize. While the acquisition of these essential attributes is not specific to the neoplastic progression of Barrett's esophagus, this review will focus on the genetic alterations that occur in Barrett's cells that contribute to the acquisition of each of the hallmarks. Moreover, potential diagnostic and therapeutic strategies for Barrett's patients aimed at each of these cancer hallmarks will be reviewed.

Cyclooxygenase-2-derived prostaglandin E2 promotes human cholangiocarcinoma cell growth and invasion through EP1 receptor-mediated activation of the epidermal growth factor receptor and Akt

Cyclooxygenase-2 (COX-2)-mediated prostaglandin synthesis has recently been implicated in human cholangiocarcinogenesis. This study was designed to examine the mechanisms by which COX-2-derived prostaglandin E2 (PGE2) regulates cholangiocarcinoma cell growth and invasion. Immunohistochemical analysis revealed elevated expression of COX-2 and the epidermal growth factor (EGF) receptor (EGFR) in human cholangiocarcinoma tissues. Overexpression of COX-2 in a human cholangiocarcinoma cell line (CCLP1) increased tumor cell growth and invasion in vitro and in severe combined immunodeficient mice. Overexpression of COX-2 or treatment with PGE2 or the EP1 receptor agonist ONO-DI-004 induced phosphorylation of EGFR and enhanced tumor cell proliferation and invasion, which were inhibited by the EP1 receptor small interfering RNA or antagonist ONO-8711. Treatment of CCLP1 cells with PGE2 or ONO-DI-004 enhanced binding of EGFR to the EP1 receptor and c-Src. Furthermore, PGE2 or ONO-DI-004 treatment also increased Akt phosphorylation, which was blocked by the EGFR tyrosine kinase inhibitors AG 1478 and PD 153035. These findings reveal that the EP1 receptor transactivated EGFR, thus activating Akt. On the other hand, activation of EGFR by its cognate ligand (EGF) increased COX-2 expression and PGE2 production, whereas blocking PGE2 synthesis or the EP1 receptor inhibited EGF-induced EGFR phosphorylation. This study reveals a novel cross-talk between the EP1 receptor and EGFR signaling that synergistically promotes cancer cell growth and invasion.

Targeted therapies for gynecologic malignancies

Despite the enormous promise that targeted therapies hold for patients with gynecologic malignancies, it is far too early to recommend any targeted therapy outside of a clinical trial. There remains considerable work to be done before targeted therapies will have a significant role in this patient population. We have learned that different tumor types express different targets, but that the mere expression of a target does not necessarily correlate with benefit from the use of the targeted agent. No less important is the challenge of determining how these agents should be studied in clinical trials, and what constitutes an active agent. To document efficacy, targeted agents would hopefully produce response (ie, shrinkage of measurable tumor), but as cytostatic agents, the ability to delay tumor growth or slow the development of symptoms would be clinically important. Combining targeted therapies with cytotoxic agents, radiation, or other targeted therapies may be important areas for study, but it is essential to demonstrate the additive or synergistic effect of the targeted therapy to an already established active one. This review covers strategies used to develop targeted agents, reviews available targeted therapies, and suggests potential roles in the treatment of gynecologic cancers.

Clinical experience with monoclonal antibodies to epidermal growth factor receptor

Recent knowledge about the intermediate steps and final consequences of ligand-dependent epidermal growth factor receptor (EGFR) activation has clearly supported the notion that EGFR plays a fundamental role in regulating the proliferation and survival of malignant neoplasms. Among the rationally designed target-based therapeutics that are being assessed, those targeting EGFR appear to be some of the most clinically relevant. The strategy of using monoclonal antibodies (mAbs) to block ligand binding to the extracellular domain of the EGFR has led to the development of therapeutics that robustly arrest malignant cell proliferation and, in some cases, induce profound tumor regression. The chimeric mAb against EGFR, cetuximab, has already been approved by regulatory agencies worldwide to treat patients with advanced colorectal cancer. Other mAbs against EGFR, particularly panitumumab (ABX-EGF), h-R3, and EMD72000, are in advanced stages of clinical development.

Gefitinib: a review of its use in the management of advanced non-small-cell lung cancer

Gefitinib (Iressa), the first commercially available epidermal growth factor receptor-tyrosine kinase (EGFR-TK) inhibitor, is indicated in the management of patients with locally advanced or metastatic non-small-cell lung cancer (NSCLC). However, approved uses differ between countries; in most markets, gefitinib is approved for third-line use only (e.g. the US, Canada and Switzerland), although in some it is approved for both second- and third-line use (e.g. Japan and Australia) and, additionally, in patients considered unsuitable for chemotherapy (e.g. Indonesia and the Philippines). Few third-line treatment options exist for patients with inoperable advanced NSCLC who have failed both platinum-based and docetaxel chemotherapies. Gefitinib represents a significant advance in the treatment of this population; a once-daily, oral dosage of 250 mg/day was well tolerated, produced objective tumour responses and disease stabilisation, and improved disease-related symptoms and quality of life. It also produced overall survival outcomes that compared favourably with historical outcomes in a similar group of patients treated with three or four different chemotherapy regimens. These findings have been supported by observations from a global compassionate-use programme. Ongoing or planned clinical trials are designed to confirm and/or further define the role of the drug in the above and other clinical settings.

Spotlight on Gefitinib in Non-Small-Cell Lung Cancer1

Gefitinib (Iressa), the first commercially available epidermal growth factor receptor-tyrosine kinase (EGFR-TK) inhibitor, is indicated in the management of patients with locally advanced or metastatic non-small-cell lung cancer (NSCLC). However, approved uses differ between countries; in most markets, gefitinib is approved for third-line use only (e.g. the US, Canada and Switzerland), although in some it is approved for both second- and third-line use (e.g. Japan and Australia) and, additionally, in patients considered unsuitable for chemotherapy (e.g. Indonesia and the Philippines). Few third-line treatment options exist for patients with inoperable advanced NSCLC who have failed both docetaxel and platinum-based chemotherapy regimens. Gefitinib represents a significant advance in the treatment of this population; a once-daily oral dosage of 250 mg/day was well tolerated, produced objective tumour responses and disease stabilization, and improved disease-related symptoms and quality of life. It also produced overall survival outcomes that compared favorably with historical outcomes in a similar group of patients treated with three or four different chemotherapy regimens. These findings have been supported by observations from a global compassionate-use program. Ongoing or planned clinical trials are designed to confirm and/or further define the role of the drug in the above and other clinical settings. Preliminary data demonstrate the presence of activating mutations in EGFR-TK among patients whose disease was highly responsive to treatment with gefitinib, although such mutations have not been correlated to all patients who benefit from the drug. Further studies are needed to fully elucidate the clinical implications of EGFR mutations and to identify patients likely to benefit from EGFR-targeted therapy.