ERBB receptor tyrosine kinases have important roles in human cancer. In particular, the expression or activation of epidermal growth factor receptor and ERBB2 are altered in many epithelial tumours, and clinical studies indicate that they have important roles in tumour aetiology and progression. Accordingly, these receptors have been intensely studied to understand their importance in cancer biology and as therapeutic targets, and many ERBB inhibitors are now used in the clinic. We will discuss the significance of these receptors as clinical targets, in particular the molecular mechanisms underlying response.

ERBB receptors and cancer: the complexity of targeted inhibitors.

ContextMore persons in the United States die from non–small cell lung
cancer (NSCLC) than from breast, colorectal, and prostate cancer combined.
In preclinical testing, oral gefitinib inhibited the growth of NSCLC tumors
that express the epidermal growth factor receptor (EGFR), a mediator of cell
signaling, and phase 1 trials have demonstrated that a fraction of patients
with NSCLC progressing after chemotherapy experience both a decrease in lung
cancer symptoms and radiographic tumor shrinkages with gefitinib.ObjectiveTo assess differences in symptomatic and radiographic response among
patients with NSCLC receiving 250-mg and 500-mg daily doses of gefitinib.Design, Setting, and PatientsDouble-blind, randomized phase 2 trial conducted from November 2000
to April 2001 in 30 US academic and community oncology centers. Patients (N
= 221) had either stage IIIB or IV NSCLC for which they had received at least
2 chemotherapy regimens.InterventionDaily oral gefitinib, either 500 mg (administered as two 250-mg gefitinib
tablets) or 250 mg (administered as one 250-mg gefitinib tablet and 1 matching
placebo).Main Outcome MeasuresImprovement of NSCLC symptoms (2-point or greater increase in score
on the summed lung cancer subscale of the Functional Assessment of Cancer
Therapy-Lung [FACT-L] instrument) and tumor regression (>50% decrease in lesion
size on imaging studies).ResultsOf 221 patients enrolled, 216 received gefitinib as randomized. Symptoms
of NSCLC improved in 43% (95% confidence interval [CI], 33%-53%) of patients
receiving 250 mg of gefitinib and in 35% (95% CI, 26%-45%) of patients receiving
500 mg. These benefits were observed within 3 weeks in 75% of patients. Partial
radiographic responses occurred in 12% (95% CI, 6%-20%) of individuals receiving
250 mg of gefitinib and in 9% (95% CI, 4%-16%) of those receiving 500 mg.
Symptoms improved in 96% of patients with partial radiographic responses.
The overall survival at 1 year was 25%. There were no significant differences
between the 250-mg and 500-mg doses in rates of symptom improvement (P = .26), radiographic tumor regression (P = .51), and projected 1-year survival (P =
.54). The 500-mg dose was associated more frequently with transient acne-like
rash (P = .04) and diarrhea (P = .006).ConclusionsGefitinib, a well-tolerated oral EGFR-tyrosine kinase inhibitor, improved
disease-related symptoms and induced radiographic tumor regressions in patients
with NSCLC persisting after chemotherapy.

https://jamanetwork.com/journals/jama/articlepdf/197532/JOC31026.pdf

Efficacy of Gefitinib, an Inhibitor of the Epidermal Growth Factor Receptor Tyrosine Kinase, in Symptomatic Patients with Non-Small Cell Lung Cancer: A Randomized Trial

Results Of 221 patients enrolled, 216 received gefitinib as randomized. Symptoms of NSCLC improved in 43% (95% confidence interval [CI], 33%-53%) of patients receiving 250 mg of gefitinib and in 35% (95% CI, 26%-45%) of patients receiving 500 mg. These benefits were observed within 3 weeks in 75% of patients. Partial radiographic responses occurred in 12% (95% CI, 6%-20%) of individuals receiving 250 mg of gefitinib and in 9% (95% CI, 4%-16%) of those receiving 500 mg. Symptoms improved in 96% of patients with partial radiographic responses. The overall survival at 1 year was 25%. There were no significant differences between the 250-mg and 500-mg doses in rates of symptom improvement (P=.26), radiographic tumor regression (P=.51), and projected 1-year survival (P=.54). The 500-mg dose was associated more frequently with transient acne-like rash (P=.04) and diarrhea (P=.006). Conclusions Gefitinib, a well-tolerated oral EGFR-tyrosine kinase inhibitor, improved disease-related symptoms and induced radiographic tumor regressions in patients with NSCLC persisting after chemotherapy.

Efficacy of Gefitinib, an Inhibitor of the Epidermal Growth Factor Receptor Tyrosine Kinase, in Symptomatic Patients With Non-Small Cell Lung Cancer

Purpose The purpose of this study was to determine whether the addition of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib (Iressa, ZD1839; AstraZeneca, Wilmington, DE) to standard first-line gemcitabine and cisplatin provides clinical benefit over gemcitabine and cisplatin alone in patients with advanced or metastatic non–small-cell lung cancer (NSCLC). Gefitinib has demonstrated encouraging efficacy in advanced NSCLC in phase II trials in pretreated patients, and a phase I trial of gefitinib in combination with gemcitabine and cisplatin showed favorable tolerability. Patients and Methods This was a phase III randomized, double-blind, placebo-controlled, multicenter trial in chemotherapy-naive patients with unresectable stage III or IV NSCLC. All patients received up to six cycles of chemotherapy (cisplatin 80 mg/m2 on day 1 and gemcitabine 1,250 mg/m2 on days 1 and 8 of the 3-week cycle) plus either gefitinib 500 mg/d, gefitinib 250 mg/d, or placebo. Daily gefitinib or placebo w...

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Gefitinib in Combination With Gemcitabine and Cisplatin in Advanced Non–Small-Cell Lung Cancer: A Phase III Trial—INTACT 1

Purpose Preclinical studies indicate that gefitinib (Iressa, ZD1839; AstraZeneca, Wilmington, DE), an orally active epidermal growth factor receptor tyrosine kinase inhibitor, may enhance antitumor efficacy of cytotoxics, and combination with paclitaxel and carboplatin had acceptable tolerability in a phase I trial. Gefitinib monotherapy demonstrated unparalleled antitumor activity for a biologic agent, with less toxicity than docetaxel, in phase II trials in refractory, advanced non–small-cell lung cancer (NSCLC). This phase III, randomized, placebo-controlled, double-blind trial evaluated gefitinib plus paclitaxel and carboplatin in chemotherapy-naive patients with advanced NSCLC. Patients and Methods Patients received paclitaxel 225 mg/m2 and carboplatin area under concentration/time curve of 6 mg/min/mL (day 1 every 3 weeks) plus gefitinib 500 mg/d, gefitinib 250 mg/d, or placebo. After a maximum of six cycles, daily gefitinib or placebo continued until disease progression. End points included overall...

/pdf/gefitinib-in-combination-with-paclitaxel-and-carboplatin-in-21pwcef2cv.pdf

Gefitinib in Combination With Paclitaxel and Carboplatin in Advanced Non–Small-Cell Lung Cancer: A Phase III Trial—INTACT 2

Transforming growth factor alpha (TGF-alpha) is an autocrine growth factor for human cancer. Overexpression of TGF-alpha and its specific receptor, the epidermal growth factor receptor (EGFR), is associated with aggressive disease and poor prognosis. The EGFR has been proposed as a target for anticancer therapy. Compounds that block ligand-induced EGFR activation have been developed. ZD-1839 (Iressa) is a p.o.-active, quinazoline derivative that selectively inhibits the EGFR tyrosine kinase and is under clinical development in cancer patients. The antiproliferative activity of ZD-1839 alone or in combination with cytotoxic drugs differing in mechanism(s) of action, such as cisplatin, carboplatin, oxaliplatin, paclitaxel, docetaxel, doxorubicin, etoposide, topotecan, and raltitrexed, was evaluated in human ovarian (OVCAR-3), breast (ZR-75-1, MCF-10A ras), and colon cancer (GEO) cells that coexpress EGFR and TGF-alpha. ZD-1839 inhibited colony formation in soft agar in a dose-dependent manner in all cancer cell lines. The antiproliferative effect was mainly cytostatic. However, treatment with higher doses resulted in a 2-4-fold increase in apoptosis. A dose-dependent supra-additive increase in growth inhibition was observed when cancer cells were treated with each cytotoxic drug and ZD-1839. The combined treatment markedly enhanced apoptotic cell death induced by single-agent treatment. ZD-1839 treatment of nude mice bearing established human GEO colon cancer xenografts revealed a reversible dose-dependent inhibition of tumor growth because GEO tumors resumed the growth rate of controls at the end of the treatment. In contrast, the combined treatment with a cytotoxic agent, such as topotecan, raltitrexed, or paclitaxel, and ZD-1839 produced tumor growth arrest in all mice. Tumors grew slowly for approximately 4-8 weeks after the end of treatment, when they finally resumed a growth rate similar to controls. GEO tumors reached a size not compatible with normal life in all control mice within 4-6 weeks and in all single agent-treated mice within 6-8 weeks after GEO cell injection. In contrast, 50% of mice treated with ZD-1839 plus topotecan, raltitrexed, or paclitaxel were still alive 10, 12, and 15 weeks after cancer cell injection, respectively. These results demonstrate the antitumor effect of this EGFR-selective tyrosine kinase inhibitor and provide a rationale for its clinical evaluation in combination with cytotoxic drugs.

https://clincancerres.aacrjournals.org/content/clincanres/6/5/2053.full.pdf

Antitumor Effect and Potentiation of Cytotoxic Drugs Activity in Human Cancer Cells by ZD-1839 (Iressa), an Epidermal Growth Factor Receptor-selective Tyrosine Kinase Inhibitor

Antitumor effect and potentiation of cytotoxic drugs activity in human cancer cells by ZD-1839 (Iressa), an EGFR-selective tyrosine kinase inhibitor.

Objective: Targeting the tumor vasculature may offer an alternative or complementary therapeutic approach to targeting growth factor signaling in lung cancer. The aim of these studies was to evaluate the antitumor effects in vivo of the combination of ZD6126, a tumor-selective vascular-targeting agent; ZD1839 (gefitinib, Iressa), an epidermal growth factor receptor tyrosine kinase inhibitor; and ionizing radiation in the treatment of non-small cell lung cancer xenograft model. Methods: Athymic nude mice with established flank A549 human non-small cell lung cancer xenograft model xenografts were treated with fractionated radiation therapy, ZD6126, ZD1839, or combinations of each treatment. ZD6126 (150 mg/kg) was given i.p. the day after each course of radiation. Animals treated with ZD1839 received 100 mg/kg per dose per animal, 5 or 7 days/wk for 2 weeks. Immunohistochemistry was done to evaluate the effects on tumor growth using an anti-Ki67 monoclonal antibody. Effects on tumor-induced vascularization were quantified using an anti–factor VIII–related antigen monoclonal antibody. Results: ZD6126 attenuated the growth of human A549 flank xenografts compared with untreated animals. Marked antitumor effects were observed when animals were treated with a combination of ZD6126 and fractionated radiation therapy with protracted tumor regression. ZD6126 + ZD1839 resulted in a greater tumor growth delay than either agent alone. Similar additive effects were seen with ZD1839 + fractionated radiation. Finally, the addition of ZD6126 to ZD1839 and radiation therapy seemed to further improve tumor growth control, with a significant tumor growth delay compared with animals treated with single agent or with double combinations. Immunohistochemistry showed that ZD1839 induced a marked reduction in A549 tumor cell proliferation. Both ZD1839 and ZD6126 treatment substantially reduced tumor-induced angiogenesis. ZD6126 caused marked vessel destruction through loss of endothelial cells and thrombosis, substantially increasing the level of necrosis seen when combined with radiation therapy. The combination of radiation therapy, ZD6126, and ZD1839 induced the greatest effects on tumor growth and angiogenesis. Conclusion: This first report shows that a selective vascular-targeting agent (ZD6126) + an anti–epidermal growth factor receptor agent (ZD1839) and radiation have additive in vivo effects in a human cancer model. Targeting the tumor vasculature offers an excellent strategy to enhance radiation cytotoxicity. Polytargeted therapy with agents that interfere with both growth factor and angiogenic signaling warrants further investigation.

https://mct.aacrjournals.org/content/molcanther/3/8/977.full.pdf

Antitumor activity of ZD6126, a novel vascular-targeting agent, is enhanced when combined with ZD1839, an epidermal growth factor receptor tyrosine kinase inhibitor, and potentiates the effects of radiation in a human non-small cell lung cancer xenograft model

Protein kinase A type I (PKAI) plays a key role in neoplastic transformation, conveys mitogenic signals from different sources, and is overexpressed in the majority of human tumors. Inhibition of PKAI by different tools results in cancer-cell growth inhibition in vitro and in vivo . We and others have recently shown that a novel class of mixed-backbone oligonucleotides targeting the PKAI subunit RIα exhibits improved pharmacokinetic properties and antitumor activity accompanied by increased apoptosis in several human cancer types in vitro and in vivo . The role of bcl-2 in the control of apoptosis has been widely documented, and the inhibition of bcl-2 expression and function may have important therapeutic implications. In fact, oligonucleotides antisense bcl-2 have shown antitumor activity in animal models and have successfully completed early clinical trials. Recent studies have demonstrated a direct role of PKA in the regulation of the bcl-2-dependent apoptotic pathway. Therefore, we have investigated the combined blockade of PKA and bcl-2 by antisense strategy as a potential therapeutic approach. The novel hybrid DNA/RNA mixed-backbone oligonucleotide antisense RIα (AS RIα) in combination with the antisense bcl-2 (AS bcl-2), cooperatively inhibited bcl-2 expression and soft agar growth and induced apoptosis in different human cancer cell lines. p.o. administration of AS RIα in combination with i.p. AS bcl-2 caused a marked antitumor effect and a significant prolongation of survival in nude mice bearing human colon cancer xenografts. Moreover, histochemical analysis of tumor specimens showed inhibition of RIα and Ki67 expression, inhibition of angiogenesis, and parallel induction of apoptosis in vivo . The results of our study imply an interaction between the PKA and bcl-2 signaling pathways and, because both antisenses have now entered Phase II trials, provide the rationale to translate this novel therapeutic strategy in a clinical setting.

https://clincancerres.aacrjournals.org/content/clincanres/7/8/2537.full.pdf

Damiano

Papers

Antitumor Effect and Potentiation of Cytotoxic Drugs Activity in Human Cancer Cells by ZD-1839 (Iressa), an Epidermal Growth Factor Receptor-selective Tyrosine Kinase Inhibitor

Antitumor effect and potentiation of cytotoxic drugs activity in human cancer cells by ZD-1839 (Iressa), an EGFR-selective tyrosine kinase inhibitor.

Antitumor activity of ZD6126, a novel vascular-targeting agent, is enhanced when combined with ZD1839, an epidermal growth factor receptor tyrosine kinase inhibitor, and potentiates the effects of radiation in a human non-small cell lung cancer xenograft model

Combined blockade of protein kinase A and bcl-2 by antisense strategy induces apoptosis and inhibits tumor growth and angiogenesis.

Cooperative antitumor effect of mixed backbone oligonucleotides targeting protein kinase A in combination with cytotoxic drugs or biologic agents.