The use of lapatinib for the treatment of patients with metastatic breast cancer is examined.
Lapatinib is a potent reversible and selective inhibitor of the tyrosine kinase domains of epidermal growth factor receptor and human epidermal growth factor receptor (HER)-2 that exerts its action by competitive binding to the intracellular ATP-binding site of the receptor. It is registered for the treatment of advanced or metastatic HER-2+ breast cancer in combination with capecitabine and for hormone receptor–positive breast cancer in combination with an aromatase inhibitor. Lapatinib administered orally once daily is moderately to well tolerated, with rash and gastrointestinal adverse events as the main toxicities. In studies on the efficacy of lapatinib, direct comparisons between lapatinib and trastuzumab are lacking. Results of ongoing randomized phase III studies with lapatinib or trastuzumab in combination with taxanes as first-line agents for metastatic breast cancer as well as in the neoadjuvant and adjuvant settings are awaited.
Lapatinib; Clinical pharmacology; EGFR; HER-2; Breast cancer; Review
The standard targeted therapy for HER2-overexpressing breast cancer is the HER2 monoclonal antibody, trastuzumab. Although effective, many patients eventually develop trastuzumab resistance. The dual EGFR/HER2 small molecule tyrosine kinase inhibitor lapatinib is approved for use in trastuzumab-refractory metastatic HER2-positive breast cancer. However, lapatinib resistance is a problem as most patients with trastuzumab-refractory disease do not benefit from lapatinib. Understanding the mechanisms underlying lapatinib resistance may ultimately facilitate development of new therapeutic strategies for HER2-overexpressing breast cancer. Our current results indicate that MEK inhibition increases lapatinib-mediated cytotoxicity in resistant HER2-overexpressing breast cancer cells. We genetically and pharmacologically blocked MEK/ERK signaling and evaluated lapatinib response by trypan blue exclusion, anchorage-independent growth assays, flow cytometric cell cycle and apoptosis analysis, and in tumor xenografts. Combined MEK inhibition and lapatinib treatment reduced phosphorylated ERK more than single agent treatment. In addition, Western blots, immunofluorescence, and immunohistochemistry demonstrated that the combination of MEK inhibitor plus lapatinib reduced nuclear expression of the MEK/ERK downstream proto-oncogene FOXM1. Genetic knockdown of MEK was tested for the ability to increase lapatinib-mediated cell cycle arrest or apoptosis in JIMT-1 and MDA361 cells. Finally, xenograft studies demonstrated that combined pharmacological inhibition of MEK plus lapatinib suppressed tumor growth and reduced expression of FOXM1 in HER2-overexpressing breast cancers that are resistant to trastuzumab and lapatinib. Our results suggest that FoxM1 contributes to lapatinib resistance downstream of MEK signaling, and supports further study of pharmacological MEK inhibition to improve response to lapatinib in HER2-overexpressing trastuzumab-resistant breast cancer.
lapatinib; HER2; erbB2; breast cancer; resistance; MEK
The antibody trastuzumab and the tyrosine kinase inhibitor lapatinib are approved by the FDA for the treatment of HER2-overexpressing breast cancer. These anti-HER2 drugs are changing the natural history of HER2-overexpressing breast cancer. However, therapeutic resistance to trastuzumab or lapatinib, as either single-agents or in combination with chemotherapy in the metastatic setting, typically occurs within months of starting therapy. Several mechanisms of trastuzumab-resistance have been reported that include signaling from other HER receptors, signaling from receptor tyrosine kinases (RTKs) outside of the HER (ErbB) family, increased phosphatidylinositol-3-kinase signaling, and the presence of truncated forms of HER2. Mechanisms of resistance to lapatinib also point to increased phosphatidylinositol 3-kinase signaling as well as derepression/activation of compensatory survival pathways. In this review, we discuss how these models and mechanisms enhance our understanding of the clinical resistance to HER2-directed therapies.
HER2 (ERBB2); trastuzumab; lapatinib; drug resistance; antibodies; tyrosine kinase inhibitors
Approximately 20%–30% of metastatic breast cancers show increased expression of the human epidermal growth factor receptor-2 (HER2) tyrosine kinase. Two HER2-specific therapies are currently approved for clinical treatment of patients with HER2-overexpressing metastatic breast cancer. Trastuzumab is a monoclonal antibody against HER2 and is approved for first-line treatment of HER2-positive metastatic breast cancer. Lapatinib is a small molecule dual inhibitor of epidermal growth factor receptor and HER2 tyrosine kinases, and is approved for trastuzumab-refractory disease. Although trastuzumab is a highly effective therapy for patients with HER2-overexpressing metastatic breast cancer, a significant number of patients in the initial clinical trials of trastuzumab monotherapy showed resistance to trastuzumab-based therapy. Further, among those who did respond, the initial trials indicated that the median time to progression was less than 1 year. Similarly, lapatinib is effective in a subset of trastuzumab-refractory cases, but the majority of patients display resistance. This review discusses the multiple molecular mechanisms of resistance that have been proposed in the literature. In addition, novel agents that are being tested for efficacy against HER2-positive breast cancer, including the antibodies pertuzumab and trastuzumab-DM1 and the immunotoxin affitoxin, are reviewed. The introduction of trastuzumab has revolutionized the clinical care of patients with HER2-positive metastatic breast cancer and has resulted in dramatic reductions in recurrences of early-stage HER2-positive breast cancer. The development and implementation of gene- and protein-based assays that measure potential molecular predictors of trastuzumab resistance will allow individualization of HER2-targeted therapeutic approaches, and may ultimately improve treatment of HER2-positive breast cancer.
ErbB2; Herceptin; trastuzumab; drug resistance; neratinib; lapatinib; affitoxin
To date, blockade of growth factor receptors is the mainstay of targeted therapy in metastatic breast cancer (mBC). Monoclonal antibodies such as trastuzumab and bevacizumab represent the first generation of molecular-based therapies. Both the HER2 inhibitors and the vascular endothelial growth factor (VEGF) antagonists have shown synergism with a broad spectrum of established cytotoxins, thus being approved for first-line treatment of mBC in combination with taxanes. As a next step, tyrosine kinase inhibitors (TKIs) have been integrated into daily routine as an alternative approach for targeting HER2: The dual HER1/2 inhibitor lapatinib demonstrated activity in trastuzumab-pretreated mBC patients in combination with capecitabine. Furthermore, chemotherapy-free regimens (trastuzumab or lapatinib plus aromatase inhibitors) have been identified as additional options for hormone receptor (HR)- and HER2-positive patients. Recently published data indicate that a combination of two biologicals such as lapatinib and trastuzumab can be effective as a treatment beyond trastuzumab related progression. Multitarget TKIs have the potential to inhibit several signaling pathways involved in breast cancer-related angiogenesis. Until now, they have failed to show a clear benefit in mBC. On the other hand, poly(ADP-ribose) polymerase (PARP) inhibition, mediated by a new class of small molecules, is an interesting area of investigation. Future directions of research in HER2-positive breast cancer focus on the evaluation of novel antibodies (pertuzumab, T-DM1), and irreversible TKIs (neratinib, BIBW 2992) and inhibitors of HER2-related downstream signaling (mTOR, TORC 1/2, PI3K/Akt) and of receptor cross-talk (IGFR).
Breast cancer, metastatic; Anti-angiogenesis; Antibody; PARP inhibition; Multitargeting
The use of trastuzumab, a monoclonal antibody that targets the human epidermal growth factor receptor 2 (HER2) alteration present in 25 to 30% of breast cancers, has been associated with improved survival outcomes in both the adjuvant and metastatic settings. However, despite the robust clinical efficacy of trastuzumab in HER2-positive metastatic breast cancer (MBC), primary and secondary resistance remains a clinical challenge. Although lapatinib has demonstrated modest activity in this setting, trials reported to date have yet to demonstrate improvements in overall survival with its use. Novel therapeutic strategies to circumvent trastuzumab resistance are warranted, and agents targeting the HER, vascular endothelial growth factor, heat shock protein 90, phosphoinositide 3 kinase/Akt/mammalian target of rapamycin, and insulin-like growth factor-1 receptor pathways represent rational approaches in the management of HER2-positive disease. In this review, early-phase and emerging trial data surrounding the use of these promising agents in HER2-positive MBC will be discussed.
HER2; breast cancer; afatinib; trastuzumab; T-DM1; lapatinib
Phosphatase and tensin homolog (PTEN) loss or activating mutations of phosphoinositol-3 (PI3) kinase (PIK3CA) may be associated with trastuzumab resistance. Trastuzumab, the humanized human epidermal growth factor receptor 2 (HER2) monoclonal antibody, and lapatinib, an epidermal growth factor receptor/HER2 tyrosine kinase inhibitor, are both established treatments for HER2-overexpressing breast cancers. Understanding of the cellular response to HER2-targeted therapies is needed to tailor treatments and to identify patients less likely to benefit.
We evaluated the effect of trastuzumab or lapatinib in three HER2-overexpressing cell lines. We confirmed the in vitro observations in two neoadjuvant clinical trials in patients with HER2 overexpression; 35 patients received trastuzumab as a single agent for the first 3 weeks, then docetaxel every 3 weeks for 12 weeks (trastuzumab regimen), whereas 49 patients received lapatinib as a single agent for 6 weeks, followed by trastuzumab/docetaxel for 12 weeks before primary surgery (lapatinib regimen). Apoptosis, Ki67, p-MAPK, p-AKT, and PTEN were assessed by immunohistochemistry. Genomic DNA was sequenced for PIK3CA mutations.
Under low PTEN conditions, in vitro data indicate that lapatinib alone and in combination with trastuzumab was effective in decreasing p-MAPK and p-AKT levels, whereas trastuzumab was ineffective. In the clinical trials, we confirmed that low PTEN or activating mutation in PIK3CA conferred resistance to the trastuzumab regimen (P = .015), whereas low PTEN tumors were associated with a high pathologic complete response rate (P = .007).
Activation of PI3 kinase pathway is associated with trastuzumab resistance, whereas low PTEN predicted for response to lapatinib. These observations support clinical trials with the combination of both agents.
A subgroup of HER2 overexpressing breast tumors co-expresses p95HER2, a truncated HER2 receptor that retains a highly functional HER2 kinase domain but lacks the extracellular domain and results in intrinsic trastuzumab resistance. We hypothesized that lapatinib, a HER2 tyrosine kinase inhibitor, would be active in these tumors. We have studied the correlation between p95HER2 expression and response to lapatinib, both in preclinical models and in the clinical setting
Two different p95HER2 animal models were used for preclinical studies. Expression of p95HER2 was analyzed in HER2 overexpressing breast primary tumors from a first line lapatinib monotherapy study (EGF20009) and a second line lapatinib in combination with capecitabine study (EGF100151). p95HER2 expression was correlated with overall response rate (complete + partial response), clinical benefit rate (complete response + partial response + stable disease ≥ 24 weeks) and progression-free survival using logistic regression and Cox-proportional hazard models.
Lapatinib inhibited tumor growth and HER2 downstream signaling of p95HER2 expressing tumors. A total of 68 and 156 tumors from studies EGF20009 and EGF100151 were evaluable, respectively, for p95HER2 detection. The percentage of p95HER2 positive patients was 20.5% in the EGF20009 study and 28.5% in the EGF100151 study. In both studies there was no statistically significant difference in progression-free survival, clinical benefit rate and overall response rate between p95HER2-positive and p95HER2-negative tumors.
Lapatinib as a monotherapy or in combination with capecitabine appears to be equally effective in patients with p95HER2-positive and p95HER2-negative HER2-positive breast tumors.
lapatinib; p95HER2; breast cancer; trastuzumab; HER2
Human epidermal growth factor receptor 2 (HER2) is the most crucial ErbB receptor tyrosine kinase (RTK) family member in HER2-positive (refered to HER2-overexpressing) breast cancer which are dependent on or "addictive" to the Phosphatidylinositol-3-kinase (PI3K) pathway. HER2-related target drugs trastuzumab and lapatinib have been the foundation of treatment of HER2--positive breast cancer. This study was designed to explore the relationship between PI3K pathway activation and the sensitivity to lapatinib in HER2--positive metastatic breast cancer patients pretreated with anthracyclins, taxanes and trastuzumab.
Sixty-seven HER2-positive metastatic breast cancer patients were recruited into a global lapatinib Expanded Access Program and 57 patients have primary tumor specimens available for determination of PI3K pathway status. PTEN status was determined by immunohistochemical staining and PIK3CA mutations were detected via PCR sequencing. All patients were treated with lapatinib 1250 mg/day continuously and capecitabine 1000 mg/m2 twice daily on a 2-week-on and 1-week-off schedule until disease progression, death, withdrawal of informed consent, or intolerable toxicity.
PIK3CA mutations and PTEN loss were detected in 12.3% (7/57) and 31.6% (18/57) of the patients, respectively. Twenty-two patients with PI3K pathway activation (defined as PIK3CA mutation and/or PTEN expression loss) had a lower clinical benefit rate (36.4% versus 68.6%, P = 0.017) and a lower overall response rate (9.1% versus 31.4%, P = 0.05), when compared with the 35 patients with no activation. A retrospective analysis of first trastuzumab-containing regimen treatment data showed that PI3K pathway activation correlated with a shorter median progression-free survival (4.5 versus 9.0 months, P = 0.013).
PIK3CA mutations occur more frequently in elder patients for HER2-positive breast cancer. PIK3CA mutations and PTEN loss are not mutually exclusive. PI3K pathway activation resulting from PTEN loss or PIK3CA mutations may lead to drug resistance to lapatinib and trastuzumab (http://ClinicalTrials.gov number, NCT00338247).
Following FDA approval of trastuzumab in 1998 and lapatinib in 2007, several clinical studies have addressed the question of whether trastuzumab and lapatinib combination therapy is better than trastuzumab alone in the metastatic breast cancer and neoadjuvant setting. In this review, updated to September 2012, we focus on the relevant clinical trials that address this question and, based on the available data, reach conclusions regarding a rational and reasonably individualized approach to the management of HER2+ breast cancer. With the FDA approval of pertuzumab in June 2012 and the likely approval of T-DM1 approaching, several ethical issues overshadow the excitement oncologists have for these new treatment options. We discuss the potential evolution of highly active anti-HER2 therapy (HAAHT) as an optimal treatment paradigm for HER2+ breast cancer. Additionally, we review lessons learned from the evolution of HAART for HIV treatment.
HER2; breast cancer; lapatinib; trastuzumab; dual; T-DM1; pertuzumab
HER2 is over-expressed in approximately 25% to 30% of human metastatic breast cancers, primarily due to gene amplification. There are currently two HER2-targeted therapies approved for clinical use, the monoclonal HER2 antibody trastuzumab and the EGFR/HER2 dual tyrosine kinase inhibitor lapatinib. Although both agents show clinical benefit in a subset of patients with metastatic breast cancer, many patients with HER2-over-expressing metastatic breast tumors do not respond to these agents. Furthermore, those who do show an initial response generally demonstrate disease progression, on average in less than one year. It has become clear that HER2 expression status alone does not adequately predict response to HER2-targeted therapy. Identification and clinical validation of molecular predictors of response to trastuzumab and lapatinib is critical for further personalizing treatment and improving clinical benefit for patients whose tumors over-express HER2. In this review, we discuss published data describing potential predictors of response or resistance to trastuzumab and lapatinib. While a discussion of the preclinical work is provided, the emphasis is placed on potential predictors that have been studied in clinical specimens such as tumor tissue or serum obtained from patients treated with HER2-targeted therapy. The present analysis and synthesis of the available literature therefore contribute towards an emerging knowledgebase to personalize breast cancer treatment taking into factors including but beyond HER2 expression.
breast cancer; erbB2; lapatinib; molecular predictor; trastuzumab
Lapatinib, a tyrosine kinase inhibitor of HER2 and EGFR and is approved, in combination with capecitabine, for the treatment of trastuzumab-refractory metastatic breast cancer. In order to establish a possible gene expression response to lapatinib, a panel of breast cancer cell lines with varying sensitivity to lapatinib were analysed using a combination of microarray and qPCR profiling.
Co-inertia analysis (CIA), a data integration technique, was used to identify transcription factors associated with the lapatinib response on a previously published dataset of 96 microarrays. RNA was extracted from BT474, SKBR3, EFM192A, HCC1954, MDAMB453 and MDAMB231 breast cancer cell lines displaying a range of lapatinib sensitivities and HER2 expression treated with 1 μM of lapatinib for 12 hours and quantified using Taqman RT-PCR. A fold change ≥ ± 2 was considered significant.
A list of 421 differentially-expressed genes and 8 transcription factors (TFs) whose potential regulatory impact was inferred in silico, were identified as associated with lapatinib response. From this group, a panel of 27 genes (including the 8 TFs) were selected for qPCR validation. 5 genes were determined to be significantly differentially expressed following the 12 hr treatment of 1 μM lapatinib across all six cell lines. Furthermore, the expression of 4 of these genes (RB1CC1, FOXO3A, NR3C1 and ERBB3) was directly correlated with the degree of sensitivity of the cell line to lapatinib and their expression was observed to “switch” from up-regulated to down-regulated when the cell lines were arranged in a lapatinib-sensitive to insensitive order. These included the novel lapatinib response-associated genes RB1CC1 and NR3C1. Additionally, Cyclin D1 (CCND1), a common regulator of the other four proteins, was also demonstrated to observe a proportional response to lapatinib exposure.
A panel of 5 genes were determined to be differentially expressed in response to lapatinib at the 12 hour time point examined. The expression of these 5 genes correlated directly with lapatinib sensitivity. We propose that the gene expression profile may represent both an early measure of the likelihood of sensitivity and the level of response to lapatinib and may therefore have application in early response detection.
Co-inertia analysis; Microarray; Lapatinib response; Breast cancer
The monoclonal antibody trastuzumab and the EGFR/HER2 tyrosine kinase inhibitor lapatinib improve the clinical outcome of patients with HER2-overexpressing breast cancer. However, the majority of metastatic cancers will eventually progress suggesting the need for other therapies. Because HER2 overexpression persists, we hypothesized that the anti-HER2 immune response induced by cancer vaccines would be an effective strategy for treating trastuzumab and lapatinib-refractory tumors. Furthermore, we hypothesized that the antibody response could synergize with lapatinib to enhance tumor inhibition. We developed a recombinant adenoviral vector expressing a kinase-inactive HER2 (Ad-HER2-ki) to use as a cancer vaccine. Vaccine-induced polyclonal HER2-specific anti-serum was analyzed for receptor internalization and signaling effects alone and in combination with lapatinib. Ad-HER2-ki vaccine induced potent T cell and antibody responses in mice and the vaccine-induced polyclonal HER2-specific anti-serum mediated receptor internalization and degradation much more effectively than trastuzumab. Our in vitro studies demonstrated that HER2-vaccine induced antibodies effectively caused a decrease in HER2 expression, but when combined with lapatinib caused significant inhibition of HER2 signaling, decreased pERK and pAKT levels, and reduced breast tumor cell proliferation. In addition, a known mechanism of resistance to lapatinib, induction of survivin, was inhibited. The combination of Ad-HER2-ki plus lapatinib also showed superior anti-tumor efficacy in vivo. Based on these results, we feel clinical studies using this approach to target HER2-overexpressing breast cancer, including trastuzumab- and lapatinib-resistant tumors is warranted.
HER2; antitumor immunity; immunization; breast cancer
The epidermal growth factor (EGF) receptors play an important role in epithelial cell function. Upon stimulation of these receptors, an extensive network of signal transduction pathways is activated, including the PI3K/AKT and Ras/Erk pathways. This activation leads to cellular proliferation and survival. In breast cancer, the EGF receptor, ErbB2 (HER2/neu), can be amplified and over-expressed and this is associated with poor prognosis and drug resistance. Trastuzumab is a monoclonal antibody against ErbB2 and has demonstrated activity in the therapy of breast cancer patients with over-expression of ErbB2, both in the metastatic and adjuvant setting. Recently, a tyrosine kinase inhibitor, lapatinib, that targets both ErbB1 and ErbB2, has also shown activity in metastatic breast cancer. In this review, we will discuss the ErbB receptors and their signaling networks in breast cancer, as well as the clinical activities of trastuzumab and lapatinib in this disease.
trastuzumab; lapatinib; ErbB receptors; breast cancer and tyrosine kinases
Patients with HER2-overexpressing metastatic breast cancer, despite initially benefiting from the monoclonal antibody trastuzumab and the EGFR/HER2 tyrosine kinase inhibitor lapatinib, will eventually have progressive disease. HER2-based vaccines induce polyclonal antibody responses against HER2 that demonstrate enhanced anti-tumor activity when combined with lapatinib in murine models. We wished to test the clinical safety, immunogenicity, and activity of a HER2-based cancer vaccine, when combined with lapatinib.
We immunized women (n = 12) with metastatic, trastuzumab-refractory, HER2-overexpressing breast cancer with dHER2, a recombinant protein consisting of extracellular domain (ECD) and a portion of the intracellular domain (ICD) of HER2 combined with the adjuvant AS15, containing MPL, QS21, CpG and liposome. Lapatinib (1250 mg/day) was administered concurrently. Peripheral blood antibody and T cell responses were measured.
This regimen was well tolerated, with no cardiotoxicity. Anti-HER2-specific antibody was induced in all patients whereas HER2-specific T cells were detected in one patient. Preliminary analyses of patient serum demonstrated downstream signaling inhibition in HER2 expressing tumor cells. The median time to progression was 55 days, with the majority of patients progressing prior to induction of peak anti-HER2 immune responses; however, 300-day overall survival was 92% (95% CI: 77-100%).
dHER2 combined with lapatinib was safe and immunogenic with promising long term survival in those with HER2-overexpressing breast cancers refractory to trastuzumab. Further studies to define the anticancer activity of the antibodies induced by HER2 vaccines along with lapatinib are underway.
HER2; Antitumor immunity; Immunization; Breast cancer
Lapatinib is a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR/ErbB1) and human epidermal growth factor receptor 2 (HER2/ErbB2). EGFR and HER2 overexpression is associated with aggressive breast cancer with a high risk of disease relapse and death. Although lapatinib targets both EGFR and HER2, its effects on HER2 appear to be more critical. The role of lapatinib in the first-line setting remains unclear. A phase II first-line monotherapy lapatinib trial in HER2-therapy-naïve metastatic breast cancer (MBC) patients confirms efficacy in HER2-positive tumors. Retrospective analysis of a phase III, first-line MBC study confirmed incremental benefit from lapatinib and paclitaxel over paclitaxel alone in HER2-positive disease. A prospective phase III study confirms superiority of letrozole and lapatinib over letrozole alone in HER2-positive MBC. Further investigation is required to define the potential first-line role for lapatinib. Particular strengths appear to be its manageable toxicity profile, lack of cross resistance with trastuzumab, activity in central nervous system disease, and synergy in combination with other anticancer therapy. Current limitations are lack of dosing recommendations from early trials, lack of predictive biomarkers beyond HER2 status, and lack of large prospective phase III trials for HER2-positive disease in the first-line setting. The role of lapatinib in HER2-negative disease is unclear.
lapatinib; HER2; metastatic; first-line
Trastuzumab is a monoclonal antibody targeted against the HER2 tyrosine kinase receptor. Although trastuzumab is a very active agent in HER2-overexpressing breast cancer, the majority of patients with metastatic HER2-overexpressing breast cancer who initially respond to trastuzumab develop resistance within 1 year of initiation of treatment and, in the adjuvant setting, progress despite trastuzumab-based therapy. The antibody-drug conjugate trastuzumab-DM1 (T-DM1) was designed to combine the biological activity of trastuzumab with the targeted delivery of a highly potent antimicrotubule agent, DM1 (N-methyl-N-[3-mercapto-1-oxopropyl]-l-alanine ester of maytansinol), a maytansine derivative, to HER2-overexpressing breast cancer cells. T-DM1 is the first antibody-drug conjugate with a nonreducible thioether linker in clinical trials. Phase I and II clinical trials of T-DM1 as a single agent and in combination with paclitaxel, docetaxel and pertuzumab have shown clinical activity and a favorable safety profile in patients with HER2-positive metastatic breast cancer. Two randomized phase III trials of T-DM1 are awaiting final results; the EMILIA trial is evaluating T-DM1 compared with lapatinib plus capecitabine, and early positive results have been reported. The MARIANNE trial is evaluating T-DM1 plus placebo versus T-DM1 plus pertuzumab versus trastuzumab plus a taxane. Here, we summarize evidence from clinical studies and discuss the potential clinical implications of T-DM1.
Improved molecular understanding of breast cancer in recent years has led to the discovery of important drug targets such as HER-2 and EGFR. Lapatinib is a potent dual inhibitor of HER-2 and EGFR. Preclinical and phase I studies have shown activity with lapatinib in a number of cancers, including breast cancer, and the drug is well tolerated. The main known drug interactions are with paclitaxel and irinotecan. The most significant side-effects of lapatinib are diarrhea and adverse skin events. Rates of cardiotoxicity compare favorably with trastuzumab, a monoclonal antibody against HER-2. This paper focuses on lapatinib in advanced and metastatic breast cancer, which remains an important therapeutic challenge. Phase II and III studies show activity as monotherapy, and in combination with chemotherapy or hormonal agents. Results from these studies suggest that the main benefit from lapatinib is in the HER-2 positive breast cancer population. Combinations of lapatinib and trastuzumab are also being studied and show encouraging results, particularly in trastuzumab-refractory metastatic breast cancer. Lapatinib may have a specific role in treating HER-2 positive CNS metastases. The role of lapatinib as neoadjuvant therapy and in early breast cancer is also being evaluated.
HER-2; EGFR; erbB; lapatinib; Tykerb®; tyrosine kinase
The article presents final analyses of overall survival from a phase III trial of lapatinib and capecitabine in patients with human epidermal growth factor receptor 2–positive locally advanced or metastatic breast cancer that progressed following prior therapy including trastuzumab.
A planned interim analysis of study EGF100151 prompted early termination of enrollment based on a longer time to progression with lapatinib and capecitabine than with capecitabine alone in patients with human epidermal growth factor receptor (HER)-2+ previously treated advanced breast cancer or metastatic breast cancer (MBC). Here, we report final analyses of overall survival.
Patients and Methods.
Women with HER-2+ MBC who progressed after regimens that included, but were not limited to, anthracyclines, taxanes, and trastuzumab, were randomized to lapatinib (1,250 mg/day) plus capecitabine (2,000 mg/m2) or capecitabine monotherapy (2,500 mg/m2) on days 1–14 of a 21-day cycle.
At enrollment termination, 399 patients were randomized, and nine were being screened and were offered combination treatment. In total, 207 and 201 patients were enrolled to combination therapy and monotherapy, respectively. Thirty-six patients receiving monotherapy crossed over to combination therapy following enrollment termination. The median overall survival times were 75.0 weeks for the combination arm and 64.7 weeks for the monotherapy arm (hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.71–1.08; p = .210). A Cox regression analysis considering crossover as a time-dependent covariate suggested a 20% lower risk for death for patients treated with combination therapy (HR, 0.80; 95% CI, 0.64–0.99; p = .043). The low incidence of serious adverse events was consistent with previously reported rates.
Although premature enrollment termination and subsequent crossover resulted in insufficient power to detect differences in overall survival, exploratory analyses demonstrate a trend toward a survival advantage with lapatinib plus capecitabine. These data continue to support the efficacy of lapatinib in patients with HER-2+ MBC.
Breast cancer; Lapatinib; Metastatic; Capecitabine; Survival; HER-2
Lapatinib, a HER2/EGFR inhibitor, is a recently approved targeted therapy for metastatic breast cancer. As lapatinib enhances the efficacy of the antimetabolite capecitabine in breast cancer patients, we lapatinib also enhance the activity of anti-cancer agents in colorectal cancer. We found that lapatinib the pro-apoptotic effects of Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL) and TRAIL receptor antibodies mapatumumab and lexatumumab. Tumors from mice treated with lapatinibTRAIL exhibited more immunostaining for cleaved caspase-8, the extrinsic cell death pathway, tumors from mice treated with lapatinib or TRAIL alone. Furthermore, combination therapy suppressed tumor growth more effectively than treatment. apatinib up-the proapoptotic TRAIL death receptors DR4 and DR5, leading to more efficient induction of apoptosis in the presence of TRAIL receptor agonistsThis activity was independent of EGFR and HER2 off-target induction of DR5 by lapatinib activation of the JNK/c-Jun signaling axis. This activity of lapatinib on TRAIL death receptor expression and signaling may confer therapeutic benefit when increased doses of lapatinib are used in combination with TRAIL-receptor-activating agents.
The treatment of breast cancer that is driven by amplification and overexpression of human epidermal growth factor receptor 2 (HER2) has been drastically improved by the development of HER2-targeted therapies including trastuzumab and lapatinib. While outcomes for patients diagnosed with HER2-positive breast cancer have been greatly impacted by these therapies, treatment resistance is common and toxicity to standard regimens remains a therapeutic challenge. Trastuzumab emtansine (T-DM1) is a novel antibody drug conjugate that consists of the HER2-targeted monoclonal antibody, trastuzumab, joined via a stable linker to a derivative of maytansine, a highly potent cytotoxic chemotherapy. While other antibody drug conjugates have been developed clinically, this is the first in its class that maintains the antitumor properties of the HER2-targeted antibody, trastuzumab, and also avoids release of the chemotherapy until the molecule is taken up inside the HER2-overexpressing cancer cell. Several phase I studies have shown T-DM1 is safe, tolerable and has activity in trastuzumab- and lapatinib-pretreated breast cancer. Moreover, phase II studies are now being reported that confirm its safety and clinical efficacy in both the frontline and heavily pretreated settings. Preliminary data from phase II studies evaluating its use in combination with other cytotoxics have also been reported and several large phase III trials are underway to evaluate its use in the HER2-positive metastatic breast cancer setting. This paper aims to provide a detailed review of the preclinical and clinical evidence relating to the mechanism of action, efficacy and safety of T-DM1 for the treatment of HER2-positive breast cancer.
breast cancer; HER2-positive; T-DM1; trastuzumab emtansine
Preclinical and clinical trials suggest that tyrosine kinase inhibitors (TKI) could supplement current therapies in metastatic breast cancer (MBC). HER-2 inhibition is still a main focus. Numerous agents targeting the epidermal growth factor receptors EGFR and HER-2 are currently tested after previous trastuzumab treatment. Lapatinib targets HER-2 and EGFR. As monotherapy, clinical activity was low. Combined with cytotoxic agents, lapatinib showed good activity (overall response rate (ORR) 24-27%) and moderate toxicity. Neratinib, a pan-ErbB TKI, showed an ORR of 26%. Neratinib combined with trastzumab was well tolerated and active (ORR = 27%). After bevacizumab's proof-of-concept studies, anti-angiogenesis remains of importance. Sunitinib inhibits the vascular endothelial growth factor receptor (VEGFR), the platelet-derived growth factor receptor (PDGFR), c-kit and the colony-stimulating factor 1 (CSF-1) receptor. Monotherapy is tolerated and moderately active in MBC. Combination trials are ongoing. Toxicities of docetaxel ± sunitinib were manageable (ORR 72.2%). Pazopanib targets VEGFR, PDGFR and c-kit. Pazopanib ± lapatinib was superior in combination (progression-free survival (PFS) = 27% vs. 19%). Axitinib has similar targets. Combined with docetaxel, it was superior compared to placebo (ORR 40% vs. 23%), with manageable toxicity. Imatinib inhibits PDGFR and c-kit. As monotherapy, it showed no clinical activity. Combination trials with chemotherapy are ongoing.
Metastatic breast cancer; Tyrosine kinase inhibitor; Her-2/neu; Anti-angiogenesis; Intracellular kinase pathways
Women with advanced or metastatic ErbB2 (HER2)-positive breast cancer have limited therapeutic options once their disease has progressed on trastuzumab-based standard initial chemotherapy regimens. Therefore, there has been a clear need for alternative treatments in this advanced setting. The small molecule lapatinib is a dual receptor tyrosine kinase inhibitor of both ErbBl and ErbB2. In the pivotal phase III trial, lapatinib combined with capecitabine has demonstrated superior efficacy over capecitabine alone in this group of patients, with a median time to tumor progression of 8.4 months in the combination therapy group versus 4.4 months in the monotherapy arm. This improvement was achieved without an increase in serious toxic effects or symptomatic cardiac events. In addition, with the advent of Lapatinib, the empirically adopted practice of continuing trastuzumab beyond progression has to be seen in a different light. This is especially true since an exploratory analysis has suggested that the earlier use of the combination lapatinib plus capecitabine is associated with a benefit in time to progression and overall survival.
Trastuzumab resistance; Dual tyrosine kinase inhibitor; Lapatinib; EGF100151 study; Treatment beyond progression
Trastuzumab (Herceptin®) is the first FDA-approved therapeutic targeting a HER-family receptor tyrosine kinase (HER2/ErbB2/neu). Although trastuzumab is effective in the treatment of HER2-positive breast cancer, a substantial proportion of patients will not respond to trastuzumab-based regimens (primary resistance), and those who do respond will often lose clinical benefit (i.e., secondary resistance). While multiple mechanisms underlying the development of secondary trastuzumab resistance have been identified, few studies have specifically examined the basis of primary trastuzumab resistance. Here, we review these studies, which, together, demonstrate that trastuzumab induces phenotypic changes in tumor cells, even when they are not growth inhibited by trastuzumab, including changes in gene expression. These changes have important clinical implications, including sensitization of malignant cells to other therapeutic drugs. In light of these observations, we propose that the conventional definition of “resistance” as it pertains to trastuzumab and, perhaps, to other targeted therapeutics, may require revision. The results of these studies will be useful in informing the direction of future basic and clinical research focused on overcoming primary trastuzumab resistance.
EGFR/ErbB/HER; trastuzumab/herceptin; breast cancer; targeted therapeutics; primary resistance
Approximately 20% of breast cancers overexpress human epidermal growth factor receptor 2 (HER2) protein, mainly as a result of gene amplification. The receptor tyrosine kinase is believed to play a critical role in the pathogenesis and further proliferation of these tumors. The application of trastuzumab, a humanized monoclonal antibody against the extracellular domain of HER2 protein, to HER2-positive metastatic breast cancer has significantly improved treatment outcomes. Following this success, several phase III trials have evaluated the role of trastuzumab in the adjuvant setting, with the result that trastuzumab use is now the standard of care for most HER2-positive early breast cancer patients. In this paper, we review these pivotal phase III trials. We also discuss unresolved issues in adjuvant treatment with trastuzumab, including target patient population, sequential or concurrent use with chemotherapy or radiation, treatment duration, cardiotoxicity, and the possibility of eliminating chemotherapy. Following confirmation of its ability to partially overcome trastuzumab resistance, we also discuss the role of lapatinib in adjuvant use.