Lapatinib in the treatment of breast cancer

Within the past 2 years, four separate groups have reported marked improvement in relapse-free survival when trastuzumab was added to adjuvant chemotherapy in patients with HER2-overexpressing breast cancer. These results add further credence to the relevance of this receptor as a tumor target. Despite the significant benefits observed in early and advanced HER2-positive breast cancer, overexpression of the receptor is still associated with a poorer prognosis and an increased risk of disease relapse, even in patients with primary operable disease. Besides cytotoxic chemotherapy, and possibly hormonal therapy, patients whose tumors exhibit resistance to trastuzumab have few molecular-targeted options available. Recently, lapatinib, a small molecule dual inhibitor of both HER2 and EGF receptors, has been developed to expand the options for treating HER-positive breast cancer.

Phase I trial combining temozolomide plus lapatinib for the treatment of brain metastases in patients with HER2-positive metastatic breast cancer: the LAPTEM trial

BACKGROUND

Brain metastases (BMs) pose a clinical challenge in breast cancer (BC). Lapatinib or temozolomide showed activity in BM. Our study assessed the combination of both drugs as treatment for patients with HER2-positive BC and BM.

METHODS

Eighteen patients were enrolled, with sixteen of them having recurrent or progressive BM. Any type of previous therapy was allowed, and disease was assessed by gadolinium (Gd)-enhanced magnetic resonance imaging (MRI). The primary end points were the evaluation of the dose-limiting toxicities (DLTs) and the determination of the maximum-tolerated dose (MTD). The secondary end points included objective response rate, clinical benefit and duration of response.

RESULTS

The lapatinib-temozolomide regimen showed a favorable toxicity profile because the MTD could not be reached. The most common adverse events (AEs) were fatigue, diarrhea and constipation. Disease stabilization was achieved in 10 out of 15 assessable patients. The estimated median survival time for the 16 patients with BM reached 10.94 months (95% CI: 1.09-20.79), whereas the median progression-free survival time was 2.60 months [95% confidence interval (CI): 1.82-3.37].

CONCLUSIONS

The lapatinib-temozolomide combination is well tolerated. Preliminary evidence of clinical activity was observed in a heavily pretreated population, as indicated by the volumetric reductions occurring in brain lesions.

Treatment of HER2-overexpressing breast cancer

The HER family of receptors consists of four closely related type 1 transmembrane TK receptors: HER1 (EGFR), HER2, HER3 and HER4. Signalling via the HER family of receptors underpins the majority of the intricate array of cellular activities on which cell survival and functionality depend. Aberrant HER2 expression and/or functionality have been implicated in the evolution of breast cancer and this receptor has proved to be a potent target for anticancer therapies, including antibody-based therapies to prevent ligand binding, dimer formation or the recruitment of antibody-dependent cell-mediated cytotoxicity, and direct kinase inhibition to prevent molecular activation and recruitment of downstream signalling partners. Novel strategies against HER2 include HER tyrosine kinase inhibitors, HSP90 inhibitors and antibody-chemotherapy conjugates. This latter approach is exemplified by T-DM1, a potent antibody that has a good safety profile and that has shown remarkable activity in patients with advanced disease. In addition, pertuzumab, an mAb that directly inhibits the formation of HER2 dimers including the HER2:HER3 dimer, offers a unique mechanism of HER3 inhibition. All these approaches have shown substantial clinical activity in patients refractory to trastuzumab. It is anticipated that with the increased availability of novel anti-HER2 agents together with a better understanding of the mechanisms of resistance to anti-HER2 agents we should be able to further improve the outcome of patients with HER2 breast cancer. There will also be an increasing tendency towards moving the study of these agents to earlier stages of the disease, namely in the adjuvant and neoadjuvant setting.

Antiangiogenic strategies in breast cancer management

Angiogenesis is considered one of the key mechanisms of tumour growth and survival. Therefore it represents an ideal pharmaceutical target. Many antiangiogenic agents have been developed so far in several solid tumours and also in breast cancer. Vascular endothelial growth factor (VEFG) is the main target and both monoclonal antibodies and small molecules belonging to the tyrosine kinase inhibitors directed against VEGF(R) have been developed. Some other therapeutic approaches have shown to exert some antiangiogenic activity, such as hormonal agents, metronomic chemotherapy, bisphosphonates and others. In this paper we provide an introduction of the current data supporting the angiogenesis in breast cancer and a review of the most relevant antiagiogenic therapies which have been investigated so far.

Dose-dense temozolomide regimen for the treatment of brain metastases from melanoma, breast cancer, or lung cancer not amenable to surgery or radiosurgery: a multicenter phase II study

BACKGROUND

Brain metastases reduce survival because therapeutic options are limited. This phase II study evaluated the efficacy of single-agent therapy with alternating weekly, dose-dense temozolomide in pretreated patients with brain metastases prospectively stratified by primary tumor type.

METHODS

Eligible patients had bidimensionally measurable brain metastases from histologically/cytologically confirmed melanoma, breast cancer (BC), or non-small-cell lung cancer (NSCLC). Prior chemotherapy, radiotherapy, and whole-brain radiotherapy (WBRT) were allowed. Patients received temozolomide 150 mg/m(2)/day (days 1-7 and 15-21 every 28- or 35-day cycle).

RESULTS

In the intent-to-treat population (N = 157; 53 melanoma, 51 BC, and 53 NSCLC), one patient had complete response, nine (6%) had partial responses, and 31 (20%) had stable disease in the brain. Median progression-free survival was 56, 58, and 66 days for melanoma, BC, and NSCLC, respectively. Median overall survival was 100 days for melanoma, 172 days for NSCLC, and not evaluable in the BC group. Thrombocytopenia was the most common adverse event causing dose modification or treatment discontinuation. Grade 4 toxic effects were rare.

CONCLUSIONS

This alternating weekly, dose-dense temozolomide regimen was well tolerated and clinically active in heavily pretreated patients with brain metastases, particularly in patients with melanoma. Combining temozolomide with WBRT or other agents may improve clinical outcomes.

Management of breast cancer with targeted agents: importance of heterogeneity. [corrected]

Breast cancer is a heterogeneous disease with different molecular drivers regulating its growth, survival and response to therapy. Breast cancer is divided in three major subtypes based on the pattern of expression of hormone receptors and HER2: luminal tumors (or HR positive), HER2 amplified tumors, and the remaining subtypes being collectively referred to as triple-negative breast cancer. While tumors within these subtypes have similar gene-expression patterns, clinical outcomes, and response to therapy, this division is far from perfect and subgroups within these groups are beginning to be identified. In terms of therapy, an increasingly rational drug development effort has resulted in agents against new molecular targets that are active against only those tumors with the targeted molecular alteration or phenotype. These agents include receptor and non-receptor tyrosine kinase inhibitors (HER1, HER2, HER3, insulin-like growth factor receptor, c-met, fibroblast growth factor receptor and HSP 90 inhibitors), intracellular signaling pathways (PI3K, AKT, mTOR), angiogenesis inhibitors and agents that interfere with DNA repair (PARP inhibitors). Thus, the overall management of breast cancer will increasingly require an understanding of breast cancer heterogeneicity, the biological nature of any given tumor as well the existence of increased personalized treatment options.

Lapatinib

The human epidermal growth factor receptor (HER) family of growth factor receptor tyrosine kinases (RTKs) plays an important role in the biology of many cancers. In breast cancer, HER2 and its homo- or heterodimerization with HER1 or HER3 are essential for cancer cell growth and survival. Patients overexpressing HER2 have a poor prognosis, which can be substantially improved upon HER2-targeted therapy using the monoclonal antibody trastuzumab. Lapatinib is a novel dual tyrosine kinase inhibitor, blocking HER1 and HER2 tyrosine kinase activity by binding to the ATP-binding site of the receptor's intracellular domain. This results in inhibition of tumor cell growth. The drug is relatively well tolerated in patients, with few and mostly low-grade adverse effects. In particular and unlike to trastuzumab, it has very little, if any, adverse effects on cardiac function. In patients with advanced HER2-positive breast cancer, lapatinib has shown substantial antitumor activity, particularly in combination with capecitabine upon progressive disease following standard therapy with antracyclines, taxanes, and trastuzumab. Ongoing and future studies will explore its role in the adjuvant therapy setting, in drug combinations other than capecitabine, and in the treatment of HER2-positive tumors other than breast cancer.

Jumping higher: is it still possible? The ALTTO trial challenge

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.

HER-2-positive metastatic breast cancer: trastuzumab and beyond

BACKGROUND

The recognition achieved in the late 1980s of human epidermal growth factor receptor 2 as an appealing therapeutic target for breast cancer has led to the development of targeted therapies for patients with human epidermal growth factor receptor 2-overexpressing breast tumors.

OBJECTIVES

The aim of the present review is to address the standard treatment of human epidermal growth factor receptor 2-positive metastatic breast cancer patients, which is currently based on the humanized monoclonal antibody trastuzumab and to describe the new treatment options available for patients progressing on trastuzumab-based therapies.

METHODS

A broad literature research was performed in order to review treatments, starting from the developmental phase of trastuzumab to the most recent biologic agents being tested in human epidermal growth factor receptor 2-positive disease.

RESULTS

Trastuzumab combined with a taxane represents the first therapeutic option for human epidermal growth factor receptor 2-positive metastatic breast cancer. However, novel combinations of trastuzumab and chemotherapy still hold great interest for their remarkable activity and good tolerability. On the other hand, the dual epidermal growth factor receptor/human epidermal growth factor receptor 2 inhibitor lapatinib has been the first drug to be approved in combination with capecitabine for the treatment of patients who progress on trastuzumab-based therapies. Moreover, in the near future, trastuzumab plus another biologic agent targeting human epidermal growth factor receptor 2, either directly or indirectly, may represent an effective 'chemotherapy-free' combination for trastuzumab-refractory patients.

Lapatinib: a dual tyrosine kinase inhibitor for metastatic breast cancer

PURPOSE

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug and food interactions, dosage and administration, and role in therapy of lapatinib in metastatic breast cancer are reviewed.

SUMMARY

Lapatinib is a small-molecule tyrosine kinase inhibitor that dually targets human epidermal growth factor receptors 1 and 2 (HER2). Unlike trastuzumab, lapatinib enters the cell and binds to the intracellular domain of the tyrosine kinase receptor, allowing for complete blockage of the autophosphorylation reaction and a complete halt to the downstream cascade of events. After oral administration, lapatinib reaches peak plasma levels within approximately 4 hours, steady-state levels within six to seven days, and has a half-life of 24 hours. Combination therapy with lapatinib and capecitabine has demonstrated superior time to progression compared with capecitabine monotherapy for the treatment of HER2-positive metastatic breast cancer refractory to anthracycline-, taxane-, and trastuzumab-containing regimens. Unlike trastuzumab, lapatinib is an orally active agent with promising clinical activity in metastatic breast cancer and is associated with a better adverse-effect profile. The most frequently reported adverse events in patients receiving combination therapy with lapatinib and capecitabine were diarrhea and hand-foot syndrome. Ongoing research has further evaluated the safety of lapatinib regarding cardiac effects and found that the majority of left ventricular ejection fraction decreases from baseline were asymptomatic and reversible.

CONCLUSION

Lapatinib has demonstrated efficacy in combination with capecitabine in patients with previously treated HER2-positive metastatic breast cancer. In patients with metastatic disease refractory to trastuzumab-, anthracycline-, and taxane-containing regimens, the addition of lapatinib to capecitabine may extend the time to disease progression and progression-free survival.

New challenges and opportunities in the management of brain metastases in patients with ErbB2-positive metastatic breast cancer

The introduction of trastuzumab for the treatment of tumors that overexpress ErbB2 (also known as HER2) has contributed significantly to recent improvements in systemic therapy for advanced breast cancer. The advances in systemic therapy have highlighted an increasing prevalence of central nervous system involvement in patients with ErbB2-positive breast cancer and a consequent need for new treatment options for brain metastases. Just as ErbB2-targeted systemic therapy has given rise to this challenge, so too could targeted therapy represent an opportunity to meet it. This Review considers the potential for targeted therapy to facilitate effective management of brain metastases in patients with ErbB2-positive breast cancer, and discusses in particular the data currently available in this setting for lapatinib, an orally available small-molecule tyrosine kinase inhibitor of ErbB1 and ErbB2.

Phase II trial of lapatinib for brain metastases in patients with human epidermal growth factor receptor 2-positive breast cancer

PURPOSE

One third of women with advanced human epidermal growth factor receptor 2 (HER-2)-positive breast cancer develop brain metastases; a subset progress in the CNS despite standard approaches. Medical therapies for refractory brain metastases are neither well-studied nor established. We evaluated the safety and efficacy of lapatinib, an oral inhibitor of epidermal growth factor receptor (EGFR) and HER-2, in patients with HER-2-positive brain metastases.

PATIENTS AND METHODS

Patients had HER-2-positive breast cancer, progressive brain metastases, prior trastuzumab treatment, and at least one measurable metastatic brain lesion. Patients received lapatinib 750 mg orally twice a day. Tumor response was assessed by magnetic resonance imaging every 8 weeks. The primary end point was objective response (complete response [CR] plus partial response [PR]) in the CNS by Response Evaluation Criteria in Solid Tumors (RECIST). Secondary end points included objective response in non-CNS sites, time to progression, overall survival, and toxicity.

RESULTS

Thirty-nine patients were enrolled. All patients had developed brain metastases while receiving trastuzumab; 37 had progressed after prior radiation. One patient achieved a PR in the brain by RECIST (objective response rate 2.6%, 95% conditional CI, 0.21% to 26%). Seven patients (18%) were progression free in both CNS and non-CNS sites at 16 weeks. Exploratory analyses identified additional patients with some degree of volumetric reduction in brain tumor burden. The most common adverse events (AEs) were diarrhea (grade 3, 21%) and fatigue (grade 3, 15%).

CONCLUSION

The study did not meet the predefined criteria for antitumor activity in highly refractory patients with HER-2-positive brain metastases. Because of the volumetric changes observed in our exploratory analysis, further studies are underway utilizing volumetric changes as a primary end point.

Current therapeutic options for breast cancer central nervous system metastases

OPINION STATEMENT

Breast cancer metastases to the central nervous system (CNS) has devastating consequences for the individual. As treatment options for metastatic breast cancer expand and as quality of life and overall survival improve, researchers are targeting potential treatments for this sanctuary site. Attention is now being focused on defining the phenotype of breast cancer that has a propensity to metastasize to the CNS. Specific therapies that penetrate the blood brain barrier as well as adjuvant therapies that decrease recurrence in the CNS are currently being investigated. We will review current approaches to the diagnosis, evaluation, and treatment of CNS metastases in breast cancer patients.

Lapatinib: a tyrosine kinase inhibitor with a clinical role in breast cancer

Lapatinib is a dual (ErbB-1 and ErB-2) receptor tyrosine kinase inhibitor (TKI) that was recently approved by the FDA for the treatment of advanced breast cancer. It shows synergy with trastuzumab, and has demonstrated clinical activity in trastuzumab-resistant tumour. This paper reviews the drug development of lapatinib from preclinical studies to the pivotal Phase III trial and ongoing clinical studies. Areas of interest include the advantages of small molecule TKIs versus antibodies in targeting HER receptors and the efficacy of lapatinib in the treatment of cerebral metastases. The surprisingly high response rate in inflammatory breast cancer raises the possibility of other novel predictive biomarkers. The potential for combination and sequencing with other biological and cytotoxic agents is both exciting and challenging.