Using fluorodeoxythymidine to monitor anti-EGFR inhibitor therapy in squamous cell carcinoma xenografts

BACKGROUND: 3'-18F-fluoro-3'-deoxy-fluorothymidine (18F-FLT), a nucleoside analog, could monitor effects of molecularly targeted therapeutics on tumor proliferation. METHODS: We tested whether (18)F-FLT positron emission tomography (PET) uptake changes are associated with antitumor effects of erlotinib in A431 xenografts or cetuximab in SCC1 xenografts. RESULTS: Compared with pretreatment FLT PET scans, 3 days of erlotinib in A431 reduced the standardized uptake value (SUV) by 18%, whereas placebo increased SUV by 1% (p = .005). One week of cetuximab in SCC1 reduced SUV by 62%, whereas placebo reduced SUV by 16% (p = .005). FLT uptake suppression following anti-epidermal growth factor receptor (EGFR) treatment was associated with reduced tumor thymidine kinase-1 (TK1) activity. In vitro TK1 knockdown studies confirmed the importance of TK1 activity on intracellular FLT accumulation suppression. CONCLUSIONS: 18F-FLT PET imaging detects tumor responses to EGFR-inhibitors within days of starting therapy. This technique may identify patients likely to benefit from EGFR-inhibitors early in their treatment course.     

Erlotinib and pantoprazole: a relevant interaction or not?

AIMS

There is increasing evidence that erlotinib exposure correlates well with treatment outcome. In this report we present a case of therapeutic drug monitoring of erlotinib in a patient with a gastric ulcer, treated with the proton pump inhibitor pantoprazole. This agent may cause an unwanted, but not always unavoidable, interaction since absorption of erlotinib is pH dependent.

METHODS

Erlotinib trough concentrations were monitored in a patient during treatment with orally and intravenously administered pantoprazole.

RESULTS

Erlotinib trough concentrations were diminished during high dose intravenously administered pantoprazole, but returned to normal when the dose was reduced and pantoprazole was administered orally.

CONCLUSIONS

More studies are needed to assess the dose dependency of the interaction between pantoprazole and erlotinib. Furthermore, we advise to monitor closely erlotinib plasma concentrations and adjust the erlotinib dose accordingly when a clinically relevant interaction is suspected and no proper dosing guidelines are available.     

Phase 2 study of bevacizumab plus erlotinib in patients with advanced hepatocellular cancer

BACKGROUND:

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) are rational targets for therapy in hepatocellular cancer (HCC).

METHODS:

Patients with histologically proven HCC and not amenable to curative or liver directed therapy were included in this 2‐stage phase 2 trial. Eligibility included an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1 and Child's Pugh score of A or B, and 1 prior systemic therapy. Patients received erlotinib 150 mg daily and bevacizumab 10 mg/kg on days 1 and 15 every 28 days. Objective tumor response was the primary end point.

RESULTS:

Twenty‐seven patients with advanced HCC (median age, 60 years) were enrolled in this multi‐institutional study. The proportion of patients with Child's A classification was 74%. One patient had a confirmed partial response and 11 (48%) achieved stable disease. Median time to disease progression was 3.0 months (95% confidence interval [CI], 1.8‐7.1). Median survival time was 9.5 months (95% CI, 7.1‐17.1). Grade 3 toxicities included rash, hypertension, fatigue, and diarrhea.

CONCLUSIONS:

In this trial, erlotinib combined with bevacizumab had minimal activity in patients with advanced HCC based on objective response and progression‐free survival. The role of targeting EGFR and VEGF in HCC needs further evaluation in molecularly selected patients. Cancer 2012. © 2011 American Cancer Society.     

Antitumor activity of HM781-36B, a highly effective pan-HER inhibitor in erlotinib-resistant NSCLC and other EGFR-dependent cancer models

The epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases has been implicated in a variety of cancers. In particular, activating mutations such as the L858R point mutation in exon 21 and the small in-frame deletions in exon 19 of the EGFR tyrosine kinase domain are correlated with sensitivity to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC) patients. Clinical treatment of patients is limited by the development of drug resistance resulting mainly from a gatekeeper mutation (T790M). In this study, we evaluated the therapeutic potential of a novel, irreversible pan-HER inhibitor, HM781-36B. The results from this study show that HM781-36B is a potent inhibitor of EGFR in vitro, including the EGFR-acquired resistance mutation (T790M), as well as HER-2 and HER-4, compared with other EGFR tyrosine kinases inhibitors (erlotinib, lapatinib and BIBW2992). HM781-36B treatment of EGFR DelE746_A750-harboring erlotinib-sensitive HCC827 and EGFR L858R/T790M-harboring erlotinib-resistant NCI-H1975 NSCLC cells results in the inhibition of EGFR phosphorylation and the subsequent deactivation of downstream signaling proteins. Additionally, HM781-36B shows an excellent efficacy in a variety of EGFR- and HER-2-dependent tumor xenograft models, including erlotinib-sensitive HCC827 NSCLC cells, erlotinib-resistant NCI-H1975 NSCLC cells, HER-2 overexpressing Calu-3 NSCLC cells, NCI-N87 gastric cancer cells, SK-Ov3 ovarian cancer cells and EGFR-overexpressing A431 epidermoid carcinoma cancer cells. On the basis of these preclinical results, HM781-36B is the most potent pan-HER inhibitor, which will be advantageous for the treatment of patients with NSCLC including clinical limitation caused by acquired mutation (EGFR T790M), breast cancer and gastric cancer.     

厄洛替尼治疗化疗失败的晚期肺癌的临床研究

目的探讨厄洛替尼治疗化疗失败的晚期非小细胞肺癌（NSCLC）患者的临床疗效和毒副反应。方法 43例经化疗失败的晚期NSCLC患者每日口服厄洛替尼150mg治疗,直至病情进展或患者不能耐受毒副反应时停药,对临床疗效、无疾病进展时间和毒副反应等进行分析。结果全组43例患者中PR14例,占32.6%;SD12例,占27.9%;PD17例,占39.5%;疾病控制率（CR＋PR＋SD）为60.5%。常见毒副反应为皮疹、腹泻。结论厄洛替尼治疗化疗失败的晚期NSCLC有一定疗效,毒副反应轻。     

Response to dual blockade of epidermal growth factor receptor (EGFR) and cycloxygenase-2 in nonsmall cell lung cancer may be dependent on the EGFR mutational status of the tumor

BACKGROUND: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated clinical benefit in patients with nonsmall cell lung cancer (NSCLC), particularly those with tumors that have EGFR-TK domain mutations. Moreover, the EGFR and cyclooxygenase (COX)-2 pathways are known to enhance the procarcinogenic effects of each other in different tumor types. Therefore, it was hypothesized that tumor EGFR mutation status may influence the effectiveness of simultaneous EGFR and COX-2 inhibition in patients with NSCLC. METHODS: Three NSCLC cell lines with varying EGFR mutation status and sensitivities to EGFR-TKIs were selected: H3255 (L858R), H1650 (del E746-A750), and H1781 (wild-type EGFR). Cells were treated with erlotinib, gefitinib, or celecoxib alone, and the combination of both EGFR-TKI inhibitors with celecoxib. Cell survival and apoptosis was assessed and correlated with the expression of COX-2, EGFR, pEGFR, Akt, pAkt, expression, and derived prostaglandin E2 (PGE(2)). RESULTS: Celecoxib by itself was found to have no effects on cell growth or apoptosis in any of the cell lines. Erlotinib and gefitinib inhibited cell growth and induced apoptosis in both mutant cell lines and did so in H1781 cells at 10-fold higher concentrations. Celecoxib when added to erlotinib or gefitinib significantly enhanced the antiproliferative and proapoptotic effects in both mutant cell lines but had no additional effects in H1781 cells. Greater down-regulation of COX-2, EGFR, pEGFR, Akt, pAkt, and PGE(2) was found when H3255 cells were treated with the combination compared with any of the single agents alone. CONCLUSIONS: The results of the current study demonstrate that the effectiveness of the addition of celecoxib to an EGFR-TKI is significantly greater in NSCLC cells with EGFR mutations, which is likely due to more complete inhibition of both pathways.     

Erlotinib (Tarceva®): a promising drug targeting epidermal growth factor receptor tyrosine kinase

Overexpression of the epidermal growth factor receptor (EGFR) is correlated with a poor prognosis in several human malignancies. In addition, cancers overexpressing EGFR respond poorly to both chemotherapy and radiation therapy. Therefore, EGFR is a viable target for cancer therapy. This review will address how EGFR blockade modulates signal transduction, leading to alterations in the cell cycle progression with secondary inhibition of proliferation and differentiation of cancer cells. As a prototypical example, erlotinib (Tarceva^®), a reversible EGFR tyrosine kinase inhibitor will be discussed. This drug has demonstrated promising antitumor activity in Phase II trials in several solid tumors and definitive Phase III studies to demonstrate clinical benefit have completed accrual.     

Mechanisms of tumor resistance to EGFR-targeted therapies

Background: Much effort has been devoted to development of cancer therapies targeting EGFR, based on its role in regulating cell growth. Small-molecule and antibody EGFR inhibitors have clinical roles based on their efficacy in a subset of cancers, generally as components of combination therapies. Many cancers are either initially resistant to EGFR inhibitors or become resistant during treatment, limiting the efficacy of these reagents. Objective/methods: To review cellular resistance mechanisms to EGFR-targeted therapies. Results/conclusions: The best validated of these mechanisms include activation of classic ATP-binding casette (ABC) multidrug transporters; activation or mutation of EGFR; and overexpression or activation of signaling proteins operating in relation to EGFR. We discuss current efforts and potential strategies to override these sources of resistance. We describe emerging systems-biology-based concepts of alternative resistance to EGFR-targeted therapies, and discuss their implications for use of EGFR-targeted and other targeted therapies.     

Targeting the epidermal growth factor receptor

The epidermal growth factor receptor (EGFR) is a member of the erbB family of tyrosine kinase receptors (RTK). The EGFR is involved in cell proliferation, metastasis and angiogenesis, and is expressed in a large proportion of epithelial tumours. The two main classes of EGFR inhibitors in clinical trials are the RTK inhibitors and the monoclonal antibodies. The clinical development of EGFR inhibitors has introduced new challenges to the design of phase I, II, and III trials. Both classes of agents can be safely administered at doses sufficient to inhibit the EGFR system. Receptor tyrosine kinase inhibitors have been extensively evaluated in non-small-cell lung cancer. In this setting, gefitinib has demonstrated activity in patients who fail initial chemotherapy. Monoclonal antibodies have been developed in combination with cytotoxic chemotherapy in several tumour types, most notably colorectal and head and neck cancer. The preliminary results suggest an increase in response rate and time to progression with the combination of cetuximab and chemotherapy in both disease models. Future issues in the development of EGFR inhibitors include the identification of biologic predictors of response, combination with other targeted agents, and their utilisation in earlier stage malignancies.     

MiRNA-7 Replacement Effect on Proliferation and Tarceva-Sensitivity in U373-MG Cell Line

Background: Deregulation of the EGFR signaling pathway activity has been shown to can be effective in resistance to EGFR-TKIs, such as Tarceva (erlotinib), in glioblastoma cells. In addition, reports have shown that the reduction of miRNA-7 expression levels is associated with an increase in the expression of EGFR. Here, we evaluated the effect of miRNA-7 on EGFR expression and sensitivity of the U373-MG glioblastoma to erlotinib. Methods: The effect of miRNA-7 on EGFR expression was examined using RT-qPCR and western blotting. Trypan blue and MTT assays were performed to explore the effect of treatments on cell growth and survival, respectively. The combination index analysis was used to evaluate the interaction between drugs. Apoptosis was measured by ELISA cell death assay. Results: We showed that miRNA-7 markedly inhibited the expression of EGFR and decreased the growth of glioblastoma cells, relative to blank control and negative control miRNA (p < 0.05). Introduction of miRNA-7 synergistically increased the sensitivity of the U373-MG cells to erlotinib. Results of apoptosis assay demonstrated that miRNA-7 can trigger apoptosis and enhance the erlotinib-mediated apoptosis. Conclusions: Our results show that miRNA-7 plays a critical role in the growth, survival and sensitivity of the U373-MG cells to erlotinib by targeting EGFR. Thus, miRNA-7 replacement therapy can become an effective therapeutic procedure in glioblastoma.