Showing papers on "Lapatinib published in 2009"
TL;DR: The review concludes with a consideration of HER-2 status in the prediction of response to non-HER-2 targeted treatments including hormonal therapy, anthracyclines, and taxanes.
Abstract: The human epidermal growth factor receptor (HER-2) oncogene encodes a transmembrane tyrosine kinase receptor that has evolved as a major classifier of invasive breast cancer and target of therapy for the disease. The validation of the general prognostic significance of HER-2 gene amplification and protein overexpression in the absence of anti-HER-2 targeted therapy is discussed in a study of 107 published studies involving 39,730 patients, which produced an overall HER-2-positive rate of 22.2% and a mean relative risk for overall survival (OS) of 2.74. The issue of HER-2 status in primary versus metastatic breast cancer is considered along with a section on the features of metastatic HER-2-positive disease. The major marketed slide-based HER-2 testing approaches, immunohistochemistry, fluorescence in situ hybridization, and chromogenic in situ hybridization, are presented and contrasted in detail against the background of the published American Society of Clinical Oncology-College of American Pathologists guidelines for HER-2 testing. Testing issues, such as the impact of chromosome 17 polysomy and local versus central HER-2 testing, are also discussed. Emerging novel HER-2 testing techniques, including mRNA-based testing by real-time polymerase chain reaction and DNA microarray methods, HER-2 receptor dimerization, phosphorylated HER-2 receptors, and HER-2 status in circulating tumor cells, are also considered. A series of biomarkers potentially associated with resistance to trastuzumab is discussed with emphasis on the phosphatase and tensin homologue deleted on chromosome ten/Akt and insulin-like growth factor receptor pathways. The efficacy results for the more recently approved small molecule HER-1/HER-2 kinase inhibitor lapatinib are also presented along with a more limited review of markers of resistance for this agent. Additional topics in this section include combinations of both anti-HER-2 targeted therapies together as well as with novel agents including bevacizumab, everolimus, and tenespimycin. A series of novel HER-2-targeting agents is also presented, including pertuzumab, ertumaxomab, HER-2 vaccines, and recently discovered tyrosine kinase inhibitors. Biomarkers predictive of HER-2 targeted therapy toxicity are included, and the review concludes with a consideration of HER-2 status in the prediction of response to non-HER-2 targeted treatments including hormonal therapy, anthracyclines, and taxanes.
1,092 citations
TL;DR: In this paper, the authors evaluated the effect of adding lapatinib, a dual tyrosine kinase inhibitor blocking epidermal growth factor receptor and HER2, to the aromatase inhibitor letrozole as first-line treatment of hormone receptor-positive metastatic breast cancer.
Abstract: Purpose Cross-talk between human epidermal growth factor receptors and hormone receptor pathways may cause endocrine resistance in breast cancer. This trial evaluated the effect of adding lapatinib, a dual tyrosine kinase inhibitor blocking epidermal growth factor receptor and human epidermal growth factor receptor 2 (HER2), to the aromatase inhibitor letrozole as first-line treatment of hormone receptor (HR) –positive metastatic breast cancer (MBC). Patients and Methods Postmenopausal women with HR-positive MBC were randomly assigned to daily letrozole (2.5 mg orally) plus lapatinib (1,500 mg orally) or letrozole and placebo. The primary end point was progression-free survival (PFS) in the HER2-positive population. Results In HR-positive, HER2-positive patients (n 219), addition of lapatinib to letrozole significantly reduced the risk of disease progression versus letrozole-placebo (hazard ratio [HR] 0.71; 95% CI, 0.53 to 0.96; P .019); median PFS was 8.2 v 3.0 months, respectively. Clinical benefit (responsive or stable disease 6 months) was significantly greater for lapatinib-letrozole versus letrozole-placebo (48% v 29%, respectively; odds ratio [OR] 0.4; 95% CI, 0.2 to 0.8; P .003). Patients with centrally confirmed HR-positive, HER2-negative tumors (n 952) had no improvement in PFS. A preplanned Cox regression analysis identified prior antiestrogen therapy as a significant factor in the HER2-negative population; a nonsignificant trend toward prolonged PFS for lapatinib-letrozole was seen in patients who experienced relapse less than 6 months since prior tamoxifen discontinuation (HR 0.78; 95% CI, 0.57 to 1.07; P .117). Grade 3 or 4 adverse events were more common in the lapatinib-letrozole arm versus letrozole-placebo arm (diarrhea, 10% v 1%; rash, 1% v 0%, respectively), but they were manageable.
903 citations
01 Nov 2009
TL;DR: It is demonstrated that a combined targeted strategy with letrozole and lapatinib significantly enhances PFS and clinical benefit rates in patients with MBC that coexpresses HR and HER2.
869 citations
TL;DR: This study confirms the modest CNS antitumor activity of lapatinib and adds that further studies of Lapatinib-based regimens for CNS metastases from HER2+ breast cancer are warranted.
Abstract: Purpose: Brain metastases develop in one third of patients with advanced HER2+ breast cancer. Effective therapy for patients with central nervous system (CNS) progression after cranial radiation is extremely limited and represents a major clinical challenge. Lapatinib, an epidermal growth factor receptor/HER2 inhibitor, was associated with regressions of CNS lesions in a small phase 2 trial. The current study was done to further evaluate the CNS activity of lapatinib. The study was later amended to allow patients who progressed on lapatinib the option of receiving lapatinib plus capecitabine. Experimental Design: Eligible patients had HER2+ breast cancer, progressive brain metastases, prior trastuzumab, and cranial radiotherapy. The primary end point was CNS objective response, defined as ≥50% volumetric reduction of CNS lesion(s) in the absence of increasing steroid use, progressive neurologic signs and symptoms, or progressive extra-CNS disease. Results: Two-hundred and forty-two patients entered the study. CNS objective responses to lapatinib were observed in 6% of patients. In an exploratory analysis, 21% of patients experienced a ≥20% volumetric reduction in their CNS lesions. An association was observed between volumetric reduction and improvement in progression-free survival and neurologic signs and symptoms. Of the 50 evaluable patients who entered the lapatinib plus capecitabine extension, 20% experienced a CNS objective response and 40% experienced a ≥20% volumetric reduction in their CNS lesions. Conclusions: This study confirms the modest CNS antitumor activity of lapatinib. Additional responses were observed with the combination of lapatinib and capecitabine. Further studies of lapatinib-based regimens for CNS metastases from HER2+ breast cancer are warranted.
583 citations
TL;DR: GSK1363089 (foretinib), a multikinase inhibitor of AXL, MET, and vascular endothelial growth factor receptor currently in phase II clinical trials, restores lapatinib and trastuzumab sensitivity in these resistant cells that exhibit increased AXL expression.
Abstract: HER2-directed therapies, such as trastuzumab and lapatinib, are important treatments for breast cancer. However, some tumors do not respond or develop resistance to these agents. We isolated and characterized multiple lapatinib-resistant, HER2-positive, estrogen receptor (ER)-positive breast cancer clones derived from lapatinib-sensitive BT474 cells by chronic exposure to lapatinib. We show overexpression of AXL as a novel mechanism of acquired resistance to HER2-targeted agents in these models. GSK1363089 (foretinib), a multikinase inhibitor of AXL, MET, and vascular endothelial growth factor receptor currently in phase II clinical trials, restores lapatinib and trastuzumab sensitivity in these resistant cells that exhibit increased AXL expression. Furthermore, small interfering RNA to AXL, estrogen deprivation, or fulvestrant, an ER antagonist, decreases AXL expression and restores sensitivity to lapatinib in these cells. Taken together, these data provide scientific evidence to assess the expression of AXL in HER2-positive, ER-positive patients who have progressed on either lapatinib or trastuzumab and to test the combination of HER2-targeted agents and GSK1363089 in the clinic.
462 citations
TL;DR: The ErbB receptor family with their most prominent members EGFR and HER-2 represents validated targets for anti-cancer therapy, and anti-ErbB MoAbs and TKIs have now been approved for the treatment of advanced colorectal cancer, squamous cell carcinoma of the head and neck, advanced non-small-cell lung cancer, as well as pancreatic and breast cancer.
Abstract: Dysregulation of human epidermal growth factor receptor (ErbB/HER) pathways by over-expression or constitutive activation can promote tumor processes including angiogenesis and metastasis and is associated with poor prognosis in many human malignancies. In addition to cancer, ErbB signaling has also been implicated in cardiovascular and neurodegenerative diseases. Conversely, inhibition of ErbB pathways with targeted agents, such as monoclonal antibodies (MoAbs) or tyrosine kinase inhibitors (TKIs), blocks cell cycle progression, inhibits the production of pro-angiogenic factors and induces apoptosis in numerous in vitro and xenograft models. Accordingly, the ErbB receptor family with their most prominent members EGFR and HER-2 represents validated targets for anti-cancer therapy, and anti-ErbB MoAbs (cetuximab, panitumumab, and trastuzumab) and TKIs (gefitinib, erlotinib, and lapatinib) have now been approved for the treatment of advanced colorectal cancer, squamous cell carcinoma of the head and neck, advanced non-small-cell lung cancer, as well as pancreatic and breast cancer. Although results have been encouraging, more work remains to be done.
401 citations
TL;DR: Lapatinib-induced accumulation of HER2 at the cell surface by lapatinib enhanced immune-mediated trastuzumab-dependent cytotoxicity is proposed that may be clinically relevant and exploitable in the therapy of patients with HER2-positive tumors.
Abstract: Lapatinib is a human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor (TKI) that has clinical activity in HER2-amplified breast cancer. In vitro studies have shown that lapatinib enhances the effects of the monoclonal antibody trastuzumab suggesting partially non-overlapping mechanisms of action. To dissect these mechanisms, we have studied the effects of lapatinib and trastuzumab on receptor expression and receptor signaling and have identified a new potential mechanism for the enhanced antitumor activity of the combination. Lapatinib, given alone or in combination with trastuzumab to HER2-overexpressing breast cancer cells SKBR3 and MCF7-HER2, inhibited HER2 phosphorylation, prevented receptor ubiquitination and resulted in a marked accumulation of inactive receptors at the cell surface. By contrast, trastuzumab alone caused enhanced HER2 phosphorylation, ubiquitination and degradation of the receptor. By immunoprecipitation and computational protein modeling techniques we have shown that the lapatinib-induced HER2 accumulation at the cell surface also results in the stabilization of inactive HER2 homo- (HER2/HER2) and hetero- (HER2/EGFR and HER2/HER3) dimers. Lapatinib-induced accumulation of HER2 and trastuzumab-mediated downregulation of HER2 was also observed in vivo, where the combination of the two agents triggered complete tumor remissions in all cases after 10 days of treatment. Accumulation of HER2 at the cell surface by lapatinib enhanced immune-mediated trastuzumab-dependent cytotoxicity. We propose that this is a novel mechanism of action of the combination that may be clinically relevant and exploitable in the therapy of patients with HER2-positive tumors.
382 citations
TL;DR: In this article, microRNAs can have a causal role in breast cancer tumorigenesis as a novel class of oncogenes or tumor suppressor genes, depending on the targets they regulate.
Abstract: An increasing amount of experimental evidence shows that microRNAs can have a causal role in breast cancer tumorigenesis as a novel class of oncogenes or tumor suppressor genes, depending on the targets they regulate. HER2 overexpression is a hallmark of a particularly aggressive subset of breast tumors, and its activation is strictly dependent on the trans-interaction with other members of HER family; in particular, the activation of the PI3K/Akt survival pathway, so critically important in tumorigenesis, is predominantly driven through phosphorylation of the kinase-inactive member HER3. Here, we show that miR-205, down-modulated in breast tumors compared with normal breast tissue, directly targets HER3 receptor, and inhibits the activation of the downstream mediator Akt. The reintroduction of miR-205 in SKBr3 cells inhibits their clonogenic potential and increases the responsiveness to tyrosine-kinase inhibitors Gefitinib and Lapatinib, abrogating the HER3-mediated resistance and restoring a potent proapoptotic activity. Our data describe miR-205 as a new oncosuppressor gene in breast cancer, able to interfere with the proliferative pathway mediated by HER receptor family. Our study also provides experimental evidence suggesting that miR-205 can improve the responsiveness to specific anticancer therapies.
351 citations
TL;DR: Results identify a previously undescribed EGFR-mediated prosurvival metabolic pathway and suggest new therapeutic approaches to treating EG FR-activated glioblastomas.
Abstract: Glioblastoma, the most common malignant brain tumor, is among the most lethal and difficult cancers to treat. Although epidermal growth factor receptor (EGFR) mutations are frequent in glioblastoma, their clinical relevance is poorly understood. Studies of tumors from patients treated with the EGFR inhibitor lapatinib revealed that EGFR induces the cleavage and nuclear translocation of the master transcriptional regulator of fatty acid synthesis, sterol regulatory element–binding protein 1 (SREBP-1). This response was mediated by Akt; however, clinical data from rapamycin-treated patients showed that SREBP-1 activation was independent of the mammalian target of rapamycin complex 1, possibly explaining rapamycin’s poor efficacy in the treatment of such tumors. Glioblastomas without constitutively active EGFR signaling were resistant to inhibition of fatty acid synthesis, whereas introduction of a constitutively active mutant form of EGFR, EGFRvIII, sensitized tumor xenografts in mice to cell death, which was augmented by the hydroxymethylglutaryl coenzyme A reductase inhibitor atorvastatin. These results identify a previously undescribed EGFR-mediated prosurvival metabolic pathway and suggest new therapeutic approaches to treating EGFR-activated glioblastomas.
314 citations
TL;DR: There was evidence of activity in HCC, but therapy with lapatinib did not meet the predefined efficacy rate.
Abstract: To evaluate the response to lapatinib, an inhibitor of epidermal growth factor receptors 1 and 2, in patients with advanced bilary tree cancer (BTC) and hepatocellular cancer (HCC). Lapatinib was dosed at 1,500 mg/day orally continuously. Fifty-seven patients were accrued (BTC 17, HCC 40). Therapy was well tolerated. The response in BTC was 0% and in HCC was 5%. The progression free survival (PFS) for BTC and HCC patients was 1.8 (95% CI: 1.7–5.2) months and 2.3 (95% CI: 1.7–5.6) months. The median survival for BTC and HCC patients was 5.2 (95% CI 3.3–∞) months and 6.2 (95% CI: 5.1–∞) months. EGFR genotyping indicated HCC patients with <20 repeats have the lowest PFS. The occurrence of any skin rash significantly prolonged PFS and survival. Lapatinib was well-tolerated. There was evidence of activity in HCC, but therapy with lapatinib did not meet the predefined efficacy rate.
266 citations
TL;DR: Evidence is provided for the therapeutic efficacy of trastuzumab in debulking and in targeting tumor-initiating cells of HER2-overexpressing tumors and it is proposed that Notch signaling regulates HER2 expression, thereby representing a critical survival pathway of tumor- initiates cells.
Abstract: Purpose: The existence of tumor-initiating cells in breast cancer has profound implications for cancer therapy. In this study, we investigated the sensitivity of tumor-initiating cells isolated from human epidermal growth factor receptor type 2 (HER2)-overexpressing carcinoma cell lines to trastuzumab, a compound used for the targeted therapy of breast cancer. Experimental Design: Spheres were analyzed by indirect immunofluorescence for HER2 cell surface expression and by real-time PCR for HER2 mRNA expression in the presence or absence of the Notch1 signaling inhibitor (GSI) or Notch1 small interfering RNA. Xenografts of HER2-overexpressing breast tumor cells were treated with trastuzumab or doxorubicin. The sphere-forming efficiency (SFE) and serial transplantability of tumors were assessed. Results: In HER2-overexpressing carcinoma cell lines, cells with tumor-initiating cell properties presented increased HER2 levels compared with the bulk cell population without modification in HER2 gene amplification. HER2 levels were controlled by Notch1 signaling, as shown by the reduction of HER2 cell surface expression and lower SFE following γ-secretase inhibition or Notch1 specific silencing. We also show that trastuzumab was able to effectively target tumor-initiating cells of HER2-positive carcinoma cell lines, as indicated by the significant decrease in SFE and the loss of serial transplantability, following treatment of HER2-overexpressing xenotransplants. Conclusions: Here, we provide evidence for the therapeutic efficacy of trastuzumab in debulking and in targeting tumor-initiating cells of HER2-overexpressing tumors. We also propose that Notch signaling regulates HER2 expression, thereby representing a critical survival pathway of tumor-initiating cells.
TL;DR: Findings suggest that Pgp and Bcrp work in concert to limit the brain-to-plasma ratio of lapatinib in mice, which has important potential consequences for the treatment of brain tumors in breast cancer patients treated with tyrosine kinase inhibitors as well as the basic understanding of ATP binding cassette transporters expressed in the blood-brain barrier on the central nervous system disposition of drugs.
Abstract: Lapatinib is a tyrosine kinase inhibitor approved for use in combination with capecitabine to treat advanced or metastatic breast cancers overexpressing human epidermal receptor 2 (ErbB2). This work investigated the role of P-glycoprotein (Pgp; the protein from the Mdr1a/b gene) and breast cancer resistance protein (Bcrp; the protein from the Bcrp1 gene) in modulating the central nervous system penetration of lapatinib at steady-state conditions in FVBn mice (wild-type), Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)/Bcrp1(-/-) knockout mice. After an intravenous infusion of lapatinib for 24 h to a targeted steady-state plasma concentration of 700 ng/ml (0.3 mg/kg/h) or 7000 ng/ml (3 mg/kg/h), lapatinib brain-to-plasma ratios were approximately 3- to 4-fold higher in Mdr1a/b(-/-) knockout mice (ratio range from 0.09 to 0.16) compared with wild-type mice (ratio range from 0.03 to 0.04). There was no difference in the brain-to-plasma ratio in the Bcrp1(-/-) knockout mice (ratio range from 0.03 to 0.04) compared with wild-type mice. In contrast, Mdr1a/b(-/-)/Bcrp1(-/-) triple knockout mice had a 40-fold higher brain-to-plasma ratio (ratio range from 1.2 to 1.7), suggesting that Pgp and Bcrp work in concert to limit the brain-to-plasma ratio of lapatinib in mice. This finding has important potential consequences for the treatment of brain tumors in breast cancer patients treated with tyrosine kinase inhibitors as well as the basic understanding of ATP binding cassette transporters expressed in the blood-brain barrier on the central nervous system disposition of drugs.
TL;DR: Careful cardiac monitoring and assessment by a cardiologist throughout the course of treatment with those TKIs that exert cardiac toxic effect is of primary importance and discontinuation of treatment is warranted for patients with severe side effects.
Abstract: Background. Cardiotoxicity is a serious side effect of drugs used to treat cancer patients. Older chemotherapy drugs such as the anthracyclins and new targeted therapies, mainly trastuzumab, have been implicated in causing clinically significant cardiac dysfunction, which may be irreversible for many patients. The advent of a new category of drugs, the tyrosine kinase inhibitors has revolutionized the treatment of chronic myeloid leukemia, gastrointestinal stromal tumors and renal cancer, while their indications include a variety of other types of tumors. Methods. Assessment of the incidence and severity of cardiac toxicity caused by the tyrosine kinase inhibitors and discussion on the molecular mechanisms and mode of diagnosis based on recent clinical trials. Review of related literature. Results. Cardiac toxicity can be caused by the tyrosine kinase inhibitors imatinib mesylate, dasatinib, nilotinib, sunitinib, sorafenib and lapatinib, while gefitinib and erlotinib have not been related to toxic effect ...
TL;DR: Lapatinib, a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and HER‐2, is assessed as second‐line therapy in patients with locally advanced or metastatic TCC.
Abstract: BACKGROUND: The treatment of recurrent transitional cell carcinoma (TCC) remains an unmet clinical need. This study assessed lapatinib, a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and HER-2, as second-line therapy in patients with locally advanced or metastatic TCC. METHODS: This was a single-arm, multicenter, open-label, prospective phase 2 study. Patients with TCC whose disease progressed on prior platinum-based chemotherapy received lapatinib until disease progression or unacceptable toxicity, with evaluations for response by Response Evaluation Criteria In Solid Tumors criteria performed every 8 weeks. The primary endpoint of the current study was objective tumor response rate. Secondary endpoints included safety, time to disease progression, and overall survival. RESULTS: Fifty-nine patients were enrolled in the study, 25 of whom (42%) could not be evaluated for response. The primary endpoint of an objective response rate (ORR) >10% was observed in 1.7% (95% confidence interval [95% CI], 0.0%-9.1%) of patients; however, 18 (31%; 95% CI, 19%-44%) patients achieved stable disease (SD). The median time to disease progression and overall survival (OS) were 8.6 weeks (95% CI, 8.0 weeks-11.3 weeks) and 17.9 weeks (95% CI, 13.1 weeks-30.3 weeks), respectively. Clinical benefit (ORR and SD) was found to be correlated with EGFR overexpression (P = .029), and, to some extent, HER-2 overexpression. The median OS was significantly prolonged in patients with tumors that overexpressed EGFR and/or HER-2 (P = .0001). Lapatinib was well tolerated. CONCLUSIONS: The study was considered to be negative because it did not meet its primary endpoint; however, further analysis demonstrated an improvement in OS in a subset of patients with tumors overexpressing EGFR and/or HER-2, which is encouraging and warrants further investigation.
TL;DR: Controversial data and explanatory factors are discussed as well as future studies for the establishment of more reliable markers for response to therapy with EGFR inhibitors to spare those who will receive no benefit or a detrimental effect from such biological agents.
Abstract: Aberrant expression of the epidermal growth factor receptor (EGFR) system has been reported in a wide range of epithelial cancers. In some studies, this has also been associated with a poor prognosis and resistance to the conventional forms of therapies. These discoveries have led to the strategic development of several kinds of EGFR inhibitors, five of which have gained US Food and Drug Administration approval for the treatment of patients with non-small-cell lung cancer (gefitinib and erlotinib), metastatic colorectal cancer (cetuximab and panitumumab), head and neck (cetuximab), pancreatic cancer (erlotinib) and breast (lapatinib) cancer. Despite these advances and recent studies on the predictive value of activating EGFR mutation and KRAS mutations with response in non-small-cell lung cancer and colon cancer patients, there is currently no reliable predictive marker for response to therapy with the anti-EGFR monoclonal antibodies cetuximab and panitumumab or the small molecule EGFR tyrosine kinase inhibitors gefitinib and erlotinib. In particular, there has been no clear association between the expression of EGFR, determined by the US Food and Drug Administration-approved EGFR PharmDX kit, and response to the EGFR inhibitors. Here, we discuss some of the controversial data and explanatory factors as well as future studies for the establishment of more reliable markers for response to therapy with EGFR inhibitors. Such investigations should lead to the selection of a more specific subpopulation of cancer patients who benefit from therapy with EGFR inhibitors, but equally to spare those who will receive no benefit or a detrimental effect from such biological agents.
TL;DR: This is the first broad-range LC-MS/MS assay covering the major currently in-use TKIs, an improvement over previous methods in terms of convenience, sensitivity, selectivity and throughput, and may contribute to filling the current knowledge gaps in the pharmacokinetics/pharmacodynamics relationships of the latest TKI developed after imatinib.
TL;DR: Single-agent lapatinib has clinical activity with manageable toxic effects in HER2-overexpressing breast cancer that progressed on trastuzumab-containing therapy.
TL;DR: The role of trastuzumab on brain metastasis (BM) in HER2-positive breast cancer patients was investigated and time to death (TTD) from BM was significantly longer in the post-T groups than in the pre-T group.
Abstract: In patients with human epidermal growth factor receptor-2 (HER2)-overexpressing breast cancer, treatment with trastuzumab has been shown to markedly improve the outcome. We investigated the role of trastuzumab on brain metastasis (BM) in HER2-positive breast cancer patients. From 1999 to 2006, 251 patients were treated with palliative chemotherapy for HER2-positive metastatic breast cancer at Samsung Medical Center. The medical records of these patients were analysed to study the effects of trastuzumab on BM prevalence and outcomes. Patients were grouped according to trastuzumab therapy: pre-T (no trastuzumab therapy) vs post-T (trastuzumab therapy). The development of BM between the two treatment groups was significantly different (37.8% for post-T vs 25.0% for pre-T, P=0.028). Patients who had received trastuzumab had longer times to BM compared with patients who were not treated with trastuzumab (median 15 months for post-T group vs 10 months for pre-T group, P=0.035). Time to death (TTD) from BM was significantly longer in the post-T group than in the pre-T group (median 14.9 vs 4.0 months, P=0.0005). Extracranial disease control at the time of BM, 12 months or more of progression-free survival of extracranial disease and treatment with lapatinib were independent prognostic factors for TTD from BM.
TL;DR: The EGF30001 trial as discussed by the authors showed lapatinib does not significantly benefit HER2-negative or HER 2-unselected patients with metastatic breast cancer (MBC).
Abstract: Purpose Lapatinib is a dual inhibitor of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) with activity in HER2-amplified metastatic breast cancer (MBC). Its role in non–HER2-amplified MBC remains unclear. EGF30001, a phase III trial of lapatinib and paclitaxel versus paclitaxel and placebo, demonstrated lapatinib does not significantly benefit HER2-negative or HER2-unselected patients with MBC. Published data support interactions between steroid hormone and peptide growth factor signaling. We hypothesized that molecular subgroups may exist within EGF30001 that would benefit from lapatinib. Methods A blinded, retrospective biomarker evaluation was performed using immunohistochemistry to semiquantitate estrogen (ER), progesterone (PR), and EGFR expression. HER2 amplification was determined by fluorescent in situ hybridization. Effects of these biomarkers on event-free survival (EFS) were examined in patients with available tissue (n = 493). Results Lapatinib impro...
TL;DR: It is appreciated that the current clinical arsenal of small molecule kinase inhibitors only contains the first weapons to be deployed in a long war against drug resistance mutations occurring in multiple kinases that target multiple cancers.
Abstract: Kinases have emerged as ubiquitous but highly challenging targets for drug discovery. The human genome has 518 kinases and many of these play critical roles in cell growth and apoptosis, making them interesting drug targets for oncology. Kinase targets including epidermal growth factor receptor (EGFR), Raf, Src, and breakpoint cluster regionsAbelson’s kinase (bcr-Abl) emerged early in the study of oncogenic proteins. Despite years of effort involving a compelling breadth of accumulated preclinical design experience (reviewed extensively by Liao and Andrews) and clinical experience (reviewed by LaRusso and Eder ), relatively few kinase inhibitors have been approved (Table 1). As an additional complication, clinical use of these inhibitors has led to the emergence of drug resistant tumors. In many patients, response to small molecule kinase inhibitors has been followed by tumor resurgence, which rendered these inhibitors less effective than expected. This resistance has been linked to a number of mechanisms that include the amplification of the oncogenic kinase gene and alternative signaling pathways or plasticity in signaling. However, in many instances, resistance has been traced to individual or groups of mutations in the drug targets that make the tumors unresponsive in the clinic. These mutants alter the binding properties of the drugs as shown by in vitro studies. When viewed across multiple cancer targets, the location of these mutations forms a compelling pattern with a number of common mechanisms elucidated with reference to this pattern. Significantly, recent characterization of mutations in the EGFR kinase has included structural and kinetic studies that have challenged assumptions about how individual drug resistance mutants are understood and to what extent mechanisms can be generalized across kinases by homology alone. This review will provide a brief overview of kinase structure and function as it pertains to drug discovery, describe the location and importance of clinical mutations, and review the emerging understanding of their impact based on sequence homology, protein crystal complexes, and biochemical/biophysical information. Underlying this discussion is our appreciation that the current clinical arsenal of small molecule kinase inhibitors only contains the first weapons to be deployed in a long war against drug resistance mutations occurring in multiple kinases that target multiple cancers. Table 1 provides a list of kinase inhibitors approved to date for various cancer indications within the U.S. Since 2001, eight inhibitors targeted to the kinase catalytic domain have been approved for clinical use led by imatinib mesylate for chronic myeloid leukemia (CML). CML has been traced to the effect of a characteristic mutation in which part of the breakpoint cluster region (BCR) gene was spliced into the Abelson kinase (Abl) gene creating a hybrid BCR-Abl gene. Known as the “Philadelphia chromosome”, the splice occurs upstream of the kinase domain. Nevertheless, pathway inhibition, by imatinib treatment (Figure 1), provides a significant benefit to patients until the emergence of resistant tumor strains. Gene sequencing efforts on the resulting resistant tumors identified a number of mutations, many in the kinase domain, which reduced the * To whom correspondence should be addressed. Telephone: 845 602 8819. Facsimile: 845 602 5682. E-mail: bikkerj@wyeth.com. a Abbreviations: Abl, Abelson kinase; AML, Acute Myeloid Leukemia; AMP-PNP, 5′-adenylyl,γ-imidodiphosphate; ATP, adenosine triphosphate; Bcr-Abl, breakpoint cluster regionsAbelson kinase; EGF(R), epidermal growth factor (receptor); CML, chronic myeloid leukemia; CMML, chronic myelomonocytic leukemia; CMPD, chronic myeloproliferative disorders; DFSP, dermatofibrossarcoma protruberans; Erb-B1/2/3/4, erythroblastic leukemia viral oncogene homologue 1/2/3/4; Erb-B1 is synonymous with EGFR and HER-1; GIST, gastroInstestinal stromal tumor; HER-1/2/3/4, human EGF receptor-1/2/3/4; HES, hypereosinophilic syndrome; NSCLC, non-small-cell lung cancer; PDGF(R), platelet derived growth factor (receptor); PKA, protein kinase A; SMCD, systemic mast cell disease; VEGF(R), vascular endothelial growth factor (receptor); WT, wild type. Copyright 2009 by the American Chemical Society
TL;DR: The addition of GDC-0941 to HER2-directed treatment could augment clinical benefit in breast cancer patients and show that inhibition of HER2 activity was essential for maximum combinatorial efficacy.
Abstract: Purpose: Oncogenic activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway is prevalent in breast cancer and has been associated with resistance to HER2 inhibitors in the clinic. We therefore investigated the combinatorial activity of GDC-0941, a novel class I PI3K inhibitor, with standard-of-care therapies for HER2-amplified breast cancer. Experimental Design: Three-dimensional laminin-rich extracellular matrix cultures of human breast cancer cells were utilized to provide a physiologically relevant approach to analyze the efficacy and molecular mechanism of combination therapies ex vivo . Combination studies were done using GDC-0941 with trastuzumab (Herceptin), pertuzumab, lapatinib (Tykerb), and docetaxel, the principal therapeutic agents that are either approved or being evaluated for treatment of early HER2-positive breast cancer. Results: Significant GDC-0941 activity (EC 50 70% of breast cancer cell lines that were examined in three-dimensional laminin-rich extracellular matrix culture. Differential responsiveness to GDC-0941 as a single agent was observed for luminal breast cancer cells upon stimulation with the HER3 ligand, heregulin. Combined treatment of GDC-0941, trastuzumab, and pertuzumab resulted in growth inhibition, altered acinar morphology, and suppression of AKT mitogen-activated protein kinase (MAPK) / extracellular signed-regulated kinase (ERK) kinase and MEK effector signaling pathways for HER2-amplified cells in both normal and heregulin-supplemented media. The GDC-0941 and lapatinib combination further showed that inhibition of HER2 activity was essential for maximum combinatorial efficacy. PI3K inhibition also rendered HER2-amplified BT-474M1 cells and tumor xenografts more sensitive to docetaxel. Conclusions: GDC-0941 is efficacious in preclinical models of breast cancer. The addition of GDC-0941 to HER2-directed treatment could augment clinical benefit in breast cancer patients.
TL;DR: The current knowledge on clinical evidence of HER2-directed therapy and the potential mechanisms of underlying resistance are summarized, including the possible clinical implications and new therapeutic options are reviewed.
TL;DR: The combined use of trastuzumab and mTOR inhibitors for the treatment of HER2+ breast cancer and the signaling and growth effects of the mTOR inhibitor RAD001 on HER2-overexpressing breast cancers were evaluated.
Abstract: Purpose: A significant fraction of HER2-overexpressing breast cancers exhibit resistance to the HER2 antibody trastuzumab. Hyperactivity of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway confers trastuzumab resistance, and mammalian target of rapamycin (mTOR) is a major downstream effector of PI3K/AKT. Therefore, we examined whether mTOR inhibitors synergize with trastuzumab. Experimental Design: Immunocompetent mice bearing HER2 + mammary tumors were treated with trastuzumab, the mTOR inhibitor rapamycin, or the combination. Mice were imaged for tumor cell death using an optical Annexin-V probe and with [ 18 F]FDG positron emission tomography. The signaling and growth effects of the mTOR inhibitor RAD001 on HER2 + cells treated with trastuzumab or lapatinib were evaluated. Results: Treatment of mice with trastuzumab plus rapamycin was more effective than single-agent treatments, inducing complete regression of 26 of 26 tumors. The combination induced tumor cell death (Annexin-V binding) and inhibited FDG uptake. Rapamycin inhibited mTOR and tumor cell proliferation as determined by phosphorylated S6 and Ki-67 immunohistochemistry, respectively. In culture, the combination of RAD001 plus trastuzumab inhibited cell growth more effectively than either drug alone. Trastuzumab partially decreased PI3K but not mTOR activity. Knockdown of TSC2 resulted in HER2-independent activation of mTOR and dampened the response to trastuzumab and lapatinib. Treatment with the HER2 inhibitor lapatinib decreased phosphorylated S6 and growth in TSC2 -expressing cells but not in TSC2 -knockdown cells. Conclusions: Inhibition of PI3K and mTOR are required for the growth-inhibitory effect of HER2 antagonists. These findings collectively support the combined use of trastuzumab and mTOR inhibitors for the treatment of HER2 + breast cancer. (Clin Cancer Res 2009;15(23):7266–76)
TL;DR: Increased understanding of HER-2 signaling in breast cancer, and of response and resistance to Herceptin antagonists, will aid the development of strategies to overcome resistance toHER-2 targeted therapies.
Abstract: Amplification of the HER-2 gene occurs in approximately 25% of breast cancers, causing up-regulation of key signaling pathways which control cell growth and survival. In breast cancer patients, HER-2 overexpression correlates with an aggressive phenotype and poor prognosis. HER-2, therefore, has become the focus of many anti-cancer therapeutic approaches. Trastuzumab (Herceptin), a humanized monoclonal antibody directed against the extracellular domain of HER-2, was the first FDA-approved HER-2-targeted therapy for the treatment of metastatic breast cancer. However, not all HER-2-overexpressing patients respond to trastuzumab and most that initially respond develop resistance within one year of treatment. Trastuzumab resistance has been studied in cell line models of resistance and several mechanisms of resistance have been proposed. More recent anti-HER-2 strategies involve targeting its tyrosine kinase domain; for example, lapatinib (Tykerb) is a dual HER-2 and EGFR tyrosine kinase inhibitor and has shown efficacy as a single agent and in combination with other therapeutics. A number of novel HER-2 antagonists are currently in preclinical or clinical development, including both monoclonal antibodies and small molecule inhibitors. Increased understanding of HER-2 signaling in breast cancer, and of response and resistance to HER-2 antagonists, will aid the development of strategies to overcome resistance to HER-2 targeted therapies.
TL;DR: These large increases in lapatinib bioavailability and absolute variability support the recommendation for dosing in the fasted state to achieve consistent therapeutic exposure andribers and patients should consider the potential consequences of toxicity or diminished efficacy that might result from dosing without regard to variations in diet.
Abstract: Purpose This study was conducted to characterize the effect of food on the relative bioavailability of lapatinib. Patients and Methods A single 1,500-mg, oral dose of lapatinib was administered to 27 patients with advanced solid tumors on each of three occasions that were 1 week apart, in random order: after an overnight fast, with a low-fat breakfast, and with a high-fat breakfast. Results The low-fat breakfast produced mean increases in lapatinib area under the concentration-time curve (AUC) of 167% (2.67-fold) and maximum concentration (Cmax) of 142% (2.42-fold). The high-fat breakfast produced mean increases in lapatinib AUC of 325% (4.25-fold) and Cmax of 203% (3.03-fold) compared with the fasted state. Increased bioavailability in the fed state did not significantly decrease relative variability. Therefore, absolute variability in systemic exposure was increased. Conclusion These large increases in lapatinib bioavailability and absolute variability support the recommendation for dosing in the fasted...
TL;DR: The chemistry, biological activity and clinical potential of new drugs with tyrosine kinase blockers for cancer treatment are discussed.
Abstract: Tyrosine kinases (TKs) are attractive targets for cancer therapy, as quite often their abnormal signaling has been linked with tumor development and growth. Constitutive activated TKs stimulate multiple signaling pathways responsible for DNA repair, apoptosis, and cell proliferation. During the last few years, thorough analysis of the mechanism underlying tyrosine kinase's activity led to novel cancer therapy using TKs blockers. These drugs are remarkably effective in the treatment of various human tumors including head and neck, gastric, prostate and breast cancer and leukemias. The most successful example of kinase blockers is Imatinib (Imatinib mesylate, Gleevec, STI571), the inhibitor of Bcr/Abl oncoprotein, which has become a first-line therapy for chronic myelogenous leukemia. The introduction of STI571 for the treatment of leukemia in clinical oncology has had a dramatic impact on how this disease is currently managed. Others kinase inhibitors used recently in cancer therapy include Dasatinib (BMS-354825) specific for ABL non-receptor cytoplasmic kinase, Gefitinib (Iressa), Erlotinib (OSI-774, Tarceva) and Sunitinib (SU 11248, Sutent) specific for VEGF receptor kinase, AMN107 (Nilotinib) and INNO-406 (NS-187) specific for c-KIT kinase. The following TK blockers for treatment of various human tumors are in clinical development: Lapatinib (Lapatinib ditosylate, Tykerb, GW-572016), Canertinib (CI-1033), Zactima (ZD6474), Vatalanib (PTK787/ZK 222584), Sorafenib (Bay 43-9006, Nexavar), and Leflunomide (SU101, Arava). Herein, we discuss the chemistry, biological activity and clinical potential of new drugs with tyrosine kinase blockers for cancer treatment.
TL;DR: In this article, the authors investigated the relationship between HER2 and the transcription factor FoxM1 in breast cancer and found that HER2-tyrosine kinase inhibitor lapatinib significantly reduced the expression at protein, mRNA and gene promoter levels.
Abstract: The tyrosine kinase receptor, HER2 is a crucial prognostic marker and therapeutic target for breast cancer; however, the downstream targets and biological effectors of HER2 remain unclear. We investigated the relationship between HER2 and the transcription factor FoxM1 in breast cancer. HER2 and FoxM1 expression levels were compared in breast carcinoma cell lines, paraffin-embedded breast cancer patient samples and at the mRNA level in purified breast epithelial cells. To further examine the relationship between HER2 and FoxM1 expression, we either overexpressed or siRNA-mediated depleted endogenous HER2 in breast cancer cell lines. Additionally, a mammary epithelium-targeted HER2 (neu) transgenic mouse model was also used to assess the effect of HER2 on FoxM1 levels. Furthermore, the effect of the HER2-tyrosine kinase inhibitor lapatinib on FoxM1 in HER2 positive breast cancer cells was investigated. HER2 protein levels directly correlated with FoxM1 expression in both breast carcinoma cell lines and paraffin-embedded breast cancer patient samples. Moreover, in purified breast epithelial cells, overexpression of HER2 was associated with high levels of FoxM1 mRNA, suggesting that the upregulation of FoxM1 expression is at least partially mediated transcriptionally. Furthermore, overexpression or ablation of endogenous HER2 resulted in parallel changes in FoxM1 expression. Critically, mammary epithelium-targeted HER2 mouse tumours also resulted in increased FoxM1 expression, suggesting that HER2 directed FoxM1 expression occurs in vivo and may be a critical downstream effector of HER2-targeting therapies. Indeed, treatment of breast cancer cells with lapatinib reduced FoxM1 expression at protein, mRNA and gene promoter levels. Moreover, analysis of normal and breast cancer patient samples revealed that elevated FoxM1 expression at protein and mRNA levels correlated with breast cancer development, but not significantly with cancer progression and survival. Our results indicate that the HER2 receptor regulates the expression of the FoxM1 transcription factor, which has a role in breast cancer development.
TL;DR: Lapatinib is well-tolerated but seems to benefit only a subgroup of patients for whom predictive molecular or clinical characteristics are not yet fully defined, and PTEN, P-AKT, and P70S6K expression did not correlate with survival.
Abstract: Background: Hepatocellular carcinoma (HCC) is on the rise worldwide. HCC responds poorly to chemotherapy. Lapatinib is an inhibitor of epidermal growth factor receptor and HER2/NEU both implicated in hepatocarcinogenesis. This trial was designed to determine the safety and efficacy of lapatinib in HCC. Methods: A Fleming phase II design with a single stage of 25 patients with a 90% power to exclude a true response rate of HER2/NEU/CEP17 and status of downstream signal pathway proteins. Results: Twenty-six patients with HCC enrolled on this study. Nineteen percent had one prior therapy. Most common toxicities were diarrhea (73%), nausea (54%), and rash (42%). No objective responses were observed. Ten (40%) patients had stable disease as their best response including six (23%) with stable disease lasting >120 days. Median progression-free survival was 1.9 months and median overall survival was 12.6 months. Patients who developed a rash had a borderline statistically significant longer survival. Tissue and blood specimens were available on >90% of patients. No somatic mutations in EGFR (exons 18-21) were found. In contrast to our previous findings, we did not find evidence of HER2/NEU somatic mutations. PTEN, P-AKT, and P70S6K expression did not correlate with survival. Conclusions: Lapatinib is well-tolerated but seems to benefit only a subgroup of patients for whom predictive molecular or clinical characteristics are not yet fully defined. (Clin Cancer Res 2009;15(18):5895–901)