Does lapatinib,a small-molecule tyrosine kinase inhibitor,constitute a breakthrough in the treatment of breast cancer?

ErbB/HER receptor or its signal transduction pathway is an attractive therapeutic target for breast cancer. Lapatinib, an orally administered dual inhibitor of ErbB1 (EGFR) and ErbB2 (HER2) receptor tyrosine kinases has shown promising results for metastatic breast cancer (MBC). Lapatinib exhibited activity against trastuzumab-refractory MBC and showed an acceptable adverse event profile such as transient mild rash, diarrhea and nausea. The addition of lapatinib to capecitabine resulted in significantly prolonged time to progression. Large randomized trials using lapatinib following chemotherapy and surgery are ongoing for early stage HER2-overexpressing breast cancer. Various combinations with agents such as paclitaxel, aromatase inhibitors, or other molecular targeted agents are currently being investigated in clinical trials. If these approaches overcome the limitations of trastuzumab, lapatinib will become an effective treatment option for breast cancer in the near future.     

Drug Insight: intracellular inhibitors of HER2--clinical development of lapatinib in breast cancer

Targeting the human epidermal growth factor receptor type 2 (HER2) in breast cancer patients whose tumors overexpress HER2 has been clearly demonstrated to be effective in clinical trials with the monoclonal antibody trastuzumab. Not all patients, however, respond to trastuzumab therapy. Lapatinib is an oral receptor tyrosine kinase inhibitor that targets HER2 and the EGFR. Preclinical data reveal that lapatinib has activity in trastuzumab-resistant cell lines as well as synergistic activity with trastuzumab. In a pivotal phase III trial, a combination of lapatinib and capecitabine significantly decreased the risk of disease progression relative to capecitabine alone in women with HER2-positive advanced or metastatic breast cancer previously treated with anthracyclines, taxanes, and trastuzumab. Other trials are evaluating lapatinib in inflammatory breast cancer--for which encouraging data have been reported--in combination with hormone therapy, in combination with trastuzumab, and as an adjunct to adjuvant therapy for early-stage disease. Notably, lapatinib has not been associated with serious or symptomatic cardiotoxicity in clinical trials. It can cross the blood-brain barrier and might therefore have a role in preventing central-nervous-system progression. These features make lapatinib an ideal agent to evaluate more fully in HER2-positive metastatic and early-stage breast cancer.     

Lapatinib plus letrozole for postmenopausal patients with advanced HER2+/HR+ breast cancer

Lapatinib is an oral, small-molecule dual inhibitor of human EGF receptor 1 (EGFR/erbB1) and 2 (HER2/erbB2). Lapatinib has recently been approved, in combination with capecitabine, for the treatment of HER2-positive metastatic breast cancer patients failing trastuzumab therapy. Data from clinical trials are consistently showing the key role of this agent in the management of HER2-positive disease. Moreover, interesting data are suggesting a key role of lapatinib in enhancing endocrine responsiveness and/or restoring endocrine sensitivity in hormone receptor-positive disease. The present article will summarize the main data leading to the clinical development of the combination of lapatinib and the aromatase inhibitor letrozole.     

The emerging role of Lapatinib in HER2-positive breast cancer

In breast cancer, overexpression of HER2 is associated with an aggressive tumor phenotype and poor prognosis. Lapatinib has demonstrated benefit in combination with capecitabine in patients with HER2-positive locally advanced and metastatic breast cancer that has progressed after prior treatment with an anthracycline, a taxane, and trastuzumab. It has also demonstrated benefit with paclitaxel in patients with metastatic disease not previously treated with chemotherapy. This review discusses results from clinical trials suggesting an advantage with the use of lapatinib with other treatment modalities in the setting of metastatic and locally advanced disease.     

Long-term management of patients with metastatic renal cell carcinoma on targeted agents

Trastuzumab, a humanized monoclonal antibody directed against HER2, used alone or in combination with chemotherapy, has shown significant clinical benefit in improving survival in the metastatic setting, as well as halving the recurrence rate and improving survival in HER2-positive early breast cancer. Lapatinib is an orally active, reversible, small-molecule tyrosine kinase inhibitor that potently inhibits both HER1 and HER2 tyrosine kinase activity. This agent is the most advanced in terms of clinical trials and has been shown to have a favorable safety profile. Owing to the promising activity seen in advanced breast cancer, lapatinib is the ideal candidate for testing in the adjuvant setting. Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO) is a four-arm randomized trial designed to compare trastuzumab and lapatinib in women with early-stage HER2-positive breast cancer. Specifically, ALTTO will examine which anti-HER2 agent is more effective and which is their best schedule of administration, namely, what benefit will be derived by taking the drugs separately, in tandem order or in combination. Overall, 8000 patients will be enrolled worldwide.     

Lapatinib and breast cancer: current indications and outlook for the future

Lapatinib is an oral dual erbB 1/2 tyrosine kinase inhibitor that inhibits human EGF receptor 2 (HER2) and blocks the EGF receptor. Studies have shown that in patients with metastatic HER2-positive breast cancer that is resistant to trastuzumab, the addition of lapatinib to capecitabine improves progression-free survival and appears to lengthen overall survival. Furthermore, lapatinib has been studied in patients with involvement of the CNS and has been associated with stable disease and some responses. Its combination with letrozole provided an improvement in progression-free survival compared with single-agent letrozole in women with hormone receptor-positive, HER2-positive metastatic breast cancer. More recently, data suggested that the combination of lapatinib with trastuzumab significantly improves overall survival in women with metastatic breast cancer compared with single-agent lapatinib. Current indications in the USA for the use of lapatinib are for the treatment of metastatic HER2-positive breast cancer, both in combination with capecitabine in patients who have received taxane, anthracycline and traztuzumab, and in combination with letrozole for postmenopausal patients with hormone receptor- and HER2-overexpressing breast cancer. Common side effects of lapatinib include diarrhea and rash. Studies to date have found a less than 2% risk for cardiotoxicity, although most cardiac events that occurred during the studies were not attributed to lapatinib. It is important to consider that most of the patients in existing studies had already been treated with trastuzumab with no significant cardiotoxicity; therefore, future studies will show how trastuzumab-naive patients tolerate lapatinib. Ongoing research is evaluating the role of lapatinib in the adjuvant setting as a single agent or in combination with trastuzumab.     

Combined chemotherapy with molecular-targeted agent for breast cancer

Molecular-targeted agents, trastuzumab, lapatinib or bevacizumab, demonstrated efficacy in patients with breast cancer. Trastuzumab exhibited efficacy and safety for HER2-positive metastatic breast cancer, in single usage or in combination with paclitaxel, docetaxel or vinorelbine. Trastuzumab is also useful in an adjuvant setting in HER2-positive early breast cancer. However, it is not clear whether concurrent or sequential treatment is superior. Lapatinib combined with capecitabine showed efficacy against HER2-positive metastatic breast cancer. It was suggested that the combination with lapatinib and paclitaxel was effective. Bevacizumab combined with paclitaxel revealed efficacy for metastatic breast cancer. These molecular-targeted agents play an important role in treatment of breast cancer.     

A phase II study of lapatinib monotherapy in chemotherapy-refractory HER2-positive and HER2-negative advanced or metastatic breast cancer

BackgroundThe efficacy and tolerability of the epidermal growth factor receptor/human epidermal growth factor receptor type 2 (HER2) tyrosine kinase inhibitor lapatinib in refractory metastatic breast cancer were assessed.Patients and methodsIn a phase II, open-label study, patients with previously treated HER2-positive (n = 140) or HER2-negative (n = 89) metastatic breast cancer received once-daily oral lapatinib 1500 mg/day.ResultsMost (76%) patients had received four or more lines of prior therapy. The response rate in the HER2-positive cohort was 4.3% by investigator assessment and 1.4% by independent assessment. Both assessments established that ∼6% of HER2-positive patients derived clinical benefit from lapatinib, being progression free for ≥6 months. No objective tumor responses occurred in the HER2-negative cohort. Independent review assessments of median time to progression and median progression-free survival were similar in the HER2-positive and HER2-negative cohorts (9.1 and 7.6 weeks, respectively). All responders exhibited HER2 overexpression (3+ by immunohistochemistry), and five of six responders were HER2 amplified by FISH. Lapatinib-related adverse events, including diarrhea (54%), rash (30%), and nausea (24%), were primarily mild to moderate in severity.ConclusionsLapatinib monotherapy had modest clinical activity in HER2-positive metastatic breast cancer that progressed on prior trastuzumab regimens. No apparent clinical activity was observed in chemotherapy-refractory, HER2-negative disease.     

Future options in the treatment of ErbB2 (HER2)-positive breast cancer

This article overviews future trends for the treatment of ErbB2 (HER2)-positive breast cancer. It is based on a presentation given at the ECCO 14 congress, September 2007.Novel ErbB2-targeted agents and/or treatment combinations have shown promise in treating ErbB2-positive metastatic breast cancer. Combinations include two agents that both inhibit ErbB2 and existing/novel ErbB2 inhibitors with chemotherapy and/or vascular endothelial growth factor (VEGF)- and VEGF receptor (VEGFR)-targeted agents. Early data suggest lapatinib (an ErbB1/2 inhibitor that recently received European approval) may be valuable in treating and/or preventing brain metastases secondary to ErbB2-positive breast cancer. Furthermore, based on promising data in metastatic disease, adjuvant and neoadjuvant lapatinib monotherapy and combination therapy trials are ongoing in early disease. Translational research will become increasingly important with new/novel agents to optimize outcomes through individualized treatment.In summary, novel targeted agents/combinations may fulfill unmet treatment needs in ErbB2-positive breast cancer; ongoing research will confirm therapeutic potential.     

Challenges in the treatment of ErbB2 (HER2)-positive breast cancer

This article reviews the challenges and future options in the treatment of ErbB2- positive metastatic breast cancer. It summarizes a presentation from a symposium that was held at the ECCO 14 congress in 2007.Despite great progress in the management of ErbB2-positive metastatic breast cancer, significant challenges remain in these patients. Many patients do not respond to trastuzumab-containing regimens or develop progressive disease within 1 year. Continuing trastuzumab in these patients has yet to show proven clinical benefit in prospective studies. Several targeted agents have been developed to overcome the limitations of current targeted therapy for ErbB2-positive breast cancer. One such agent, lapatinib, was recently approved in Europe in combination with capecitabine in patients previously treated with trastuzumab in the metastatic setting. The intracellular site of action of lapatinib may underlie substantial clinical benefit.Based on available data to date, novel ErbB2-targeted therapies may hold significant promise in the management of ErbB2-positive metastatic breast cancer.     

Intermediate to highly suspicious calcification in breast lesions: a radio-pathologic correlation

Targeted therapies against the human epidermal growth factor receptor HER2, have led to revolutionary strides in breast cancer research and treatment. Clinical therapeutic decisions in the treatment of patients with HER2 positive metastatic breast cancer are based on appropriate patient selection, the clinical situation, and data related to the available therapeutic agents trastuzumab and lapatinib. Trastuzumab was the first agent tested and approved in 1996 as single agent for patients with chemotherapy-refractory disease, and in combination with paclitaxel as first-line treatment. This intravenous humanized monoclonal antibody is directed against the extracellular domain of the HER2 protein. Lapatinib, an oral small molecule tyrosine kinase inhibitor has more recently become available (in 2007), approved for used in combination with capecitabine for patients with HER2 positive metastatic disease that has progressed on trastuzumab. Important questions and controversies still remain and are reviewed, including patient selection for anti-HER2 treatment of metastatic disease based on HER2 testing, dose scheduling of trastuzumab, duration of therapy, tolerability, role of lapatinib and clinical significance of trastuzumab resistance and efficacy. Ongoing trials designed to maximize the therapeutic ratio of these agents, are also discussed.     

Dose-Reduced Trastuzumab Emtansine: Active and Safe in Acute Hepatic Dysfunction

Breast cancer is the most common cancer in women worldwide. The majority of deaths attributed to breast cancer are a result of metastatic disease, and 30% of early breast cancers (EBC) will develop distant disease. The 5-year survival of patients with metastatic disease is estimated at 23%. Breast cancer subtypes continue to be stratified histologically on oestrogen, progesterone and human epidermal growth factor-2 (HER2) receptor expression. HER2-positive breast cancers represent 25% of all breast cancer diagnoses. The therapies available for metastatic breast cancer (MBC) are expanding, in particular within the field of HER2-positive disease, with the approval of trastuzumab, pertuzumab, lapatinib and trastuzumab emtansine (TDM-1). Recently, TDM-1 has been shown to improve progression-free survival in HER2 MBC when compared to capecitabine and lapatinib in clinical studies. Its main toxicities are deranged liver function tests and thrombocytopenia. There have also been cases of acute liver failure. Therefore, its use in acute hepatic dysfunction, to our knowledge, has been neither studied nor reported. We report a patient with progressive HER2-positive MBC who had previously responded to multiple HER2-targeted therapies that presented with acute hepatic dysfunction. She was treated with dose-reduced TDM-1 safely, with clear evidence of rapid biochemical, clinical and radiological response. This allowed dose escalation of TDM-1, and the patient maintains an ongoing response.Key Words: Human epidermal growth factor-2, Metastatic breast cancer, Hepatic dysfunction, Trastuzumab emtansine     

Phase I safety, pharmacokinetics, and clinical activity study of lapatinib (GW572016), a reversible dual inhibitor of epidermal growth factor receptor tyrosine kinases, in heavily pretreated patients with metastatic carcinomas.

PURPOSE: This study (EGF10004) assessed the safety/tolerability, pharmacokinetics, and clinical activity of daily oral dosing with lapatinib (GW572016) in patients with ErbB1-expressing and/or ErbB2-overexpressing advanced-stage refractory solid tumors. PATIENTS AND METHODS: Heavily pretreated patients with ErbB1-expressing and/or ErbB2-overexpressing metastatic cancers were randomly assigned to one of five dose cohorts of lapatinib administered once daily. Pharmacokinetic samples were obtained on days 1 and 20. Clinical response was assessed every 8 weeks. RESULTS: Sixty-seven patients with metastatic solid tumors were treated with lapatinib. The most frequently reported drug-related adverse events were diarrhea (42%) and rash (31%). No grade 4 drug-related adverse events were reported. Five grade 3 drug-related toxicities (gastrointestinal events and rash) were experienced by four patients. Drug-related interstitial pneumonitis or cardiac dysfunction associated with other ErbB-targeted therapies was not reported. Four patients with trastuzumab-resistant metastatic breast cancer-two of whom were classified as having inflammatory breast cancer-had partial responses (PRs). Twenty-four patients with various other carcinomas experienced stable disease, of whom 10 received lapatinib for > or = 6 months. The relationships between lapatinib dose or serum concentration and clinical response could not be adequately characterized due to the limited response data. The incidence of diarrhea increased with increasing dose, whereas the incidence of rash was not related to dose. CONCLUSION: Lapatinib was well tolerated at doses ranging from 500 to 1,600 mg once daily. Clinical activity was observed in heavily pretreated patients with ErbB1-expressing and/or ErbB2-overexpressing metastatic cancers, including four PRs in patients with trastuzumab-resistant breast cancers and prolonged stable disease in 10 patients.     

Cardiac toxicity of ErbB2-targeted therapies: what do we know?

The potential for cardiac toxicity in association with targeted biologic agents was first observed with trastuzumab, a monoclonal antibody that targets the ErbB2/HER2 receptor. In the pivotal trial of trastuzumab in ErbB2-positive metastatic cancer, an increased incidence of serious cardiac events was observed, particularly when trastuzumab was administered in combination with anthracyclines. The ErbB2 receptor is expressed on cardiomyocytes, in addition to tumor tissue, where it exerts a protective effect on cardiac function; thus, interference with ErbB2-signaling may block this protective effect. However, in contrast to anthracycline-induced cardiac toxicity, trastuzumab-related cardiac dysfunction does not appear to increase with cumulative dose or to be associated with ultrastructural changes in the myocardium and is generally reversible. When used in adjuvant regimens for the treatment of ErbB2-positive early-stage breast cancer, trastuzumab has been shown to significantly improve disease-free and overall survival. The incidence of class III/IV congestive heart failure (CHF) ranged from 0.4%-3.8% in the major adjuvant trastuzumab trials. More recently, small-molecule tyrosine kinase inhibitors such as lapatinib have been investigated for the treatment of ErbB2-positive metastatic breast cancer. In a comprehensive analysis of cardiac safety data from all lapatinib trials completed to date, which included 3558 healthy volunteers and patients with a variety of solid cancers on 43 trials, the overall incidence of left ventricular ejection fraction declines was 1.6%, with 0.2% of patients experiencing symptomatic CHF. Risk factors that might predict for cardiac dysfunction with ErbB2-targeted therapy are actively under investigation and will aid in the identification of at-risk populations and in the development of strategies for risk minimization in the future. It is important to note that, while careful cardiac monitoring is required for all patients receiving ErbB2-targeted therapy in any disease setting, the overall impact of these agents on the outcomes of patients with ErbB2-positive breast cancer has been dramatic and positive.     

Lapatinib-associated toxicity and practical management recommendations

Lapatinib is an oral receptor tyrosine kinase inhibitor, inhibiting both the ErbB-1 and ErbB-2 receptors. Lapatinib has been shown to have activity in ErbB-2-overexpressing breast cancer in several phase II and III clinical trials. Specifically, lapatinib is effective in patients with metastatic breast cancer, with inflammatory breast cancer, and possibly, with brain metastases. An ongoing clinical trial and another anticipated clinical trial will investigate lapatinib as adjuvant treatment in early-stage disease. Lapatinib has specific toxicities, the most common being diarrhea and rash. Cardiac toxicity is rarely seen with lapatinib. This paper reviews lapatinib-associated toxicities and provides practical management recommendations based on available data.     

Tykerb for breast cancer

There are four members of the ErbB family: the epidermal growth factor(EGF)receptor(also called HER1 or EGFR), HER2, HER3 and HER4. Dimerization is the process whereby two HER receptor molecules associate to form a noncovalent complex. HER dimers are the active receptor forms required for transmission of external stimuli to the interior of the cell. HER dimerization occurs upon ligand binding and both HER homodimers and heterodimers can be formed in the process. However, HER2 appears to be the preferred dimerization partner of the other HER family members. Fifteen～20% of all breast cancers are HER2 positive and have a poor prognosis. Trastuzumab is an excellent, rationally-designed targeted cancer treatment. It is a recombinant, humanized, anti-HER2 monoclonal antibody that specifically binds to the extracellular area of HER2. However, the overall trastuzumab response rate is low, and the causes of trastuzumab resistance are poorly understood. Thus, there is a need for alternative anti-HER2 strategies for trastuzumab-resistant disease. Lapatinib is an orally administered small-molecule, reversible inhibitor of both EGFR and HER2 tyrosine kinase, and its activities include subsequent inhibition of its down- stream MAPK-ERK1/2, and the AKT signaling pathway. Lapatinib is more active when used in combination with capecitabine. For women with trastuzumab pre-treated HER2-positive breast cancer, Here, I will review the basics of EGFR and HER, and the treatment strategy for HER2-positive breast cancer with lapatinib.     

Safety and efficacy of neratinib (HKI-272) plus vinorelbine in the treatment of patients with ErbB2-positive metastatic breast cancer pretreated with anti-HER2 therapy

BackgroundNeratinib (HKI-272) is a potent irreversible pan-ErbB tyrosine kinase inhibitor with clinical activity in patients with ErbB2/HER2-positive breast cancer.Patients and methodsPhase I of this open-label, phase I/II study investigated the maximum tolerated dose (MTD) of oral neratinib (160 or 240 mg/day) plus vinorelbine (25 mg/m²; days 1 and 8 of each 21-day cycle) in patients with solid tumors. Phase II assessed the safety, clinical activity, and pharmacokinetics of the combination in patients with HER2-positive metastatic breast cancer; the primary efficacy end point was objective response (OR).ResultsIn phase I (n = 12), neratinib (240 mg) plus vinorelbine (25 mg/m²) was established as the MTD. In phase II, 79 patients with HER2-positive metastatic breast cancer were treated at the MTD. The most common treatment-related adverse events were diarrhea (96%), neutropenia (54%), and nausea (50%). Three patients discontinued treatment due to diarrhea. No clinically important skin side-effects were observed. The OR rate in assessable phase II patients was 41% (no prior lapatinib) and 8% (prior lapatinib). There was no evidence of pharmacokinetic interaction between neratinib and vinorelbine.ConclusionNeratinib plus vinorelbine showed promising antitumor activity and no unexpected toxic effects in HER2-positive metastatic breast cancer patients.Trial registrationClinicalTrials.gov #NCT00706030.     

Clinical recommendations for the use of lapatinib ditosylate plus capecitabine for patients with advanced or metastatic HER2-positive breast cancer

Primary and acquired resistance to trastuzumab pose a therapeutic challenge when treating patients with HER2 (erbB-2)-positive locally advanced or metastatic breast cancer (MBC). The recent introduction of lapatinib (Tykerb/Tyverb, GlaxoSmithKline, Brentford, UK) provides a new management option for such patients. A prospective, randomized phase III clinical trial has confirmed that lapatinib in combination with capecitabine extends time to progressive disease in HER2-positive MBC, compared with capecitabine alone in patients with disease progression despite prior anthracycline, taxane and trastuzumab therapy. Preliminary data also indicate that lapatinib may exert a beneficial effect on brain metastases, a common sanctuary site for HER2-positive breast cancer following trastuzumab treatment. The tolerability of lapatinib is commensurate with that of other erbB family tyrosine kinase inhibitors and no significant new adverse events have emerged following its introduction into clinical practice. In particular, no additive cardiotoxicity has been observed when lapatinib is prescribed after trastuzumab therapy. Based on the published literature and supplemented by clinical experience, this article provides practical management recommendations for the use of lapatinib plus capecitabine in patients with MBC. Issues addressed include patient selection, baseline evaluation and monitoring for clinical benefit. The minimization and management of adverse events is also discussed in detail, particularly the dermatological and gastrointestinal effects, which are the most clinically significant side-effects of lapatinib therapy. Further recommendations cover the minimization of drug interactions, anticipated dosing alterations and the optimal employment of oral anticancer regimens.     

Lapatinib: A Sword With Two Edges

Lapatinib is an oral dual tyrosine kinase inhibitor targeting EGFR1 and EGFR2 (HER2). Phase I trials have shown that lapatinib is well tolerated, with mild diarrhea and skin rush as common adverse effects, and low cardiotoxicity. Phase II and III trials provided evidences on clinical effectiveness in advanced or metastatic breast cancer and potential against brain metastases. Lapatinib is active in combination with trastuzumab and in trastuzumab-resistant patients, moreover it has synergistic action with capecitabine. Several clinical trials are in progress to explore the effectiveness of lapatinib in other combinations and against several tumor types.     

Lapatinib monotherapy in patients with relapsed, advanced, or metastatic breast cancer: efficacy, safety, and biomarker results from Japanese patients phase II studies

Background:

HER2-positive metastatic breast cancer (MBC) relapsing after trastuzumab-based therapy may require continued HER2 receptor inhibition to control the disease and preserve the patients'' quality-of-life. Efficacy and safety of lapatinib monotherapy was evaluated in Japanese breast cancer patients after trastuzumab-based therapies.

Methods:

In studies, EGF100642 and EGF104911 evaluated the efficacy and safety of oral lapatinib given 1500 mg once daily in patients with advanced or MBC. All patients progressed on anthracyclines and taxanes; HER2-positive patients had also progressed on trastuzumab.

Results:

For HER2-positive tumours (n=100), objective response rate was 19.0% (95% confidence interval (CI): 11.8–28.1) and clinical benefit rate (CBR) was 25.0% (95% CI: 16.9–34.7). One out of 22 HER2-negative tumour was documented as complete response (n=22). The median time-to-progression (TTP) in the HER2-positive and HER2-negative groups was 13.0 and 8.0 weeks (P=0.007); median overall survival was 58.3 and 40.0 weeks, respectively. The most frequent adverse event was diarrhoea. TTP and CBR were significantly associated with HER2 expression. Patients with tumours harbouring an H1047R PIK3CA mutation or low expression of PTEN derived clinical benefit from lapatinib.

Conclusion:

Lapatinib monotherapy had shown anti-tumour activity in Japanese patients with HER2-positive MBC that relapsed after trastuzumab-based therapy, including those with brain metastases. Patients benefiting from lapatinib may have biomarker profiles differing from that reported for trastuzumab.