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

Intracranial Response Rate in Patients with Breast Cancer Brain Metastases after Systemic Therapy

Simple Summary

For many years, patients with breast cancer and brain metastases were excluded from participation in clinical trials. It was believed that anticancer drugs could not cross the blood–brain barrier. However, recent evidence strongly suggests that some drugs can act against brain metastases, with the greatest intracranial response rate reported in the case of capecitabine, neratinib plus capecitabine, trastuzumab deruxtecan and tucatinib plus trastuzumab and capecitabine. In this article, we discuss the achievements in systemic therapy of breast cancer patients with brain metastases. We stress on the newest clinical trial results which indicate tremendous progress in HER2-positive breast cancer. On the other hand, in patients with triple-negative breast cancer or hormone-receptor-positive brain metastases, much fewer compounds were discovered. Based on the presented results, patients with active brain metastases should be routinely included in clinical trials with novel agents.

Abstract

Brain metastases are detected in 5% of patients with breast cancer at diagnosis. The rate of brain metastases is higher in HER2-positive and triple-negative breast cancer patients (TNBC). In patients with metastatic breast cancer, the risk of brain metastases is much higher, with up to 50% of the patients having two aggressive biological breast cancer subtypes. The prognosis for such patients is poor. Until recently, little was known about the response to systemic therapy in brain metastases. The number of trials dedicated to breast cancer with brain metastases was scarce. Our review summarizes the current knowledge on this topic including very significant results of clinical trials which have been presented very recently. We focus on the intracranial response rate of modern drugs, including new antibody–drug conjugates, HER2- targeted tyrosine kinase inhibitors and other targeted therapies. We highlight the most effective and promising drugs. On the other hand, we also suggest that further efforts are needed to improve the prognosis, especially patients with TNBC and brain metastases. The information contained in this article can help oncologists make treatment-related decisions.

Management of Brain and Leptomeningeal Metastases from Breast Cancer

The management of breast cancer (BC) has rapidly evolved in the last 20 years. The improvement of systemic therapy allows a remarkable control of extracranial disease. However, brain (BM) and leptomeningeal metastases (LM) are frequent complications of advanced BC and represent a challenging issue for clinicians. Some prognostic scales designed for metastatic BC have been employed to select fit patients for adequate therapy and enrollment in clinical trials. Different systemic drugs, such as targeted therapies with either monoclonal antibodies or small tyrosine kinase molecules, or modified chemotherapeutic agents are under investigation. Major aims are to improve the penetration of active drugs through the blood-brain barrier (BBB) or brain-tumor barrier (BTB), and establish the best sequence and timing of radiotherapy and systemic therapy to avoid neurocognitive impairment. Moreover, pharmacologic prevention is a new concept driven by the efficacy of targeted agents on macrometastases from specific molecular subgroups. This review aims to provide an overview of the clinical and molecular factors involved in the selection of patients for local and/or systemic therapy, as well as the results of clinical trials on advanced BC. Moreover, insight on promising therapeutic options and potential directions of future therapeutic targets against BBB and microenvironment are discussed.

Evolving treatment strategies of brain metastases from breast cancer: current status and future direction

Remarkable progress in breast cancer treatment has improved patient survival, resulting in an increased incidence of brain metastasis (BM). Current treatment options for BM are limited and are generally used for palliative purposes. Historically, local treatment, consisting of radiotherapy and surgery, is the standard of care due to delivery limitations of systemic treatments through the blood-brain barrier. However, as novel biological mechanisms for tumors and BM have been discovered, several innovative systemic agents, such as small-molecular-targeted therapy and immunotherapy, have begun to change the treatment paradigm. In addition, efforts to maximize antitumor effects have been attempted using combination therapy, informed by tumor biology. In this comprehensive review, we will highlight various clinical trials investigating the treatment of BM in breast cancer patients, discuss presently available treatment options, and suggest potential directions of future therapeutic targets.

Temozolomide in secondary prevention of HER2-positive breast cancer brain metastases

Brain metastases occur in up to 25-55% of patients with metastatic HER2-positive breast cancer. Standard treatment has high rates of recurrence or progression, limiting survival and quality of life in most patients. Temozolomide (TMZ) is known to penetrate the blood-brain barrier and is US FDA approved for treatment of glioblastoma. Our group has demonstrated that low doses of TMZ administered in a prophylactic, metronomic fashion can significantly prevent development of brain metastases in murine models of breast cancer. Based on these findings, we initiated a secondary-prevention clinical trial with oral TMZ given to HER2-positive breast cancer patients with brain metastases after recent local treatment in combination with T-DM1 for systemic control of disease. Primary end point is freedom from new brain metastases at 1 year. (NCT03190967).

HER2-targeted therapy prolongs survival in patients with HER2-positive breast cancer and intracranial metastatic disease: a systematic review and meta-analysis

BACKGROUND

Intracranial metastatic disease (IMD) is a serious and known complication of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The role of targeted therapy for patients with HER2-positive breast cancer and IMD remains unclear. In this study, we sought to evaluate the effect of HER2-targeted therapy on IMD from HER2-positive breast cancer.

METHODS

We searched MEDLINE, EMBASE, CENTRAL, and gray literature sources for interventional and observational studies reporting survival, response, and safety outcomes for patients with IMD receiving HER2-targeted therapy. We pooled outcomes through meta-analysis and examined confounder effects through forest plot stratification and meta-regression. Evidence quality was evaluated using GRADE (PROSPERO CRD42020161209).

RESULTS

A total of 97 studies (37 interventional and 60 observational) were included. HER2-targeted therapy was associated with prolonged overall survival (hazard ratio [HR] 0.47; 95% confidence interval [CI], 0.39-0.56) without significantly prolonged progression-free survival (HR 0.52; 95% CI, 0.27-1.02) versus non-targeted therapy; the intracranial objective response rate was 19% (95% CI, 12-27%), intracranial disease control rate 62% (95% CI, 55-69%), intracranial complete response rate 0% (95% CI, 0-0.01%), and grade 3+ adverse event rate 26% (95% CI, 11-45%). Risk of bias was high in 40% (39/97) of studies.

CONCLUSION

These findings support a potential role for systemic HER2-targeted therapy in the treatment of patients with IMD from HER2-positive metastatic breast cancer.

Precision Medical Approaches to the Diagnoses and Management of Brain Metastases

OPINION STATEMENT

Brain metastases represent a common and devastating complication of cancer with survival on the order of a few months in most patients. Melanoma, breast cancer, and lung cancer remain the primary disease histologies with the highest rates of metastatic spread to the brain. The incidence of brain metastases has continued to rise, likely explained by multiple factors. Improvement in progression-free survival in systemic cancer is likely attributable to advances in medical therapy, earlier supportive and symptomatic care, and improved precision around diagnosis and detection. In this context, longer survival and improved extracranial control disease has likely contributed to the increased development of metastatic spread intracranially. The foundation of management remains systemic therapy, as well as a combination of surgery and radiation therapy. In the era of targeted therapies, specific agents have demonstrated improved CNS penetration, however with varying degrees of durable responses. Most patients develop resistance to targeted agents, limiting their duration of use for patients. In this era of personalized medicine, the role of genomic characterization in cancer has been critical in the field of brain metastases, as alterations unique to both the brain metastases and its systemic predecessor have been identified, potentially offering new avenues for therapy.

Tyrosine kinase inhibitors for brain metastases in HER2-positive breast cancer

Approximately 30-50% of advanced HER2-positive breast cancer patients will develop central nervous system (CNS) metastases, with an annual risk of around 10%, and a half of them will die from brain progression. An increased risk of brain metastases is also seen in patients with early HER2-positive breast cancer administered curative therapy. Brain metastases in HER2-positive breast cancer patients usually constitute the first site of recurrence. The administration of anti-HER2 monoclonal antibodies, trastuzumab and pertuzumab, considerably delays the onset of symptomatic brain disease: however, the limited penetration of these compounds into the CNS hinders their efficacy. The small-molecule tyrosine kinase inhibitors of epidermal growth factor receptors family have established activity in HER2-positive breast cancer in both advanced disease and neoadjuvant setting. Favorable physico-chemical properties of these compounds allow them for a more efficient penetration through the blood-brain barrier, and hold the promise for more effective prevention and treatment of brain metastases. In this article we review the role of currently available or investigational HER2 tyrosine kinase inhibitors: lapatinib, neratinib, afatinib and tucatinib in the treatment of brain metastases in HER2-positive breast cancer patients.

Radiosensitizing effect of lapatinib in human epidermal growth factor receptor 2-positive breast cancer cells

Trastuzumab has been widely used for the treatment of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer, however, it cannot easily cross the blood-brain barrier (BBB) and is known to increase the incidence of brain metastases. In contrast, lapatinib has a low molecular weight and can cross the BBB and it could be useful to treat brain metastases in patients with HER2-positive breast cancer.

To explore the impact of lapatinib on radiation response, we conducted an in vitro experiment using SKBR3 and BT474 breast carcinoma cells exhibiting HER2/neu amplification. Lapatinib down-regulated phosphorylated (p)-HER2, p-epidermal growth factor receptor, p-AKT, and p-extracellular signal-regulated kinase. Pretreatment of lapatinib increased the radiosensitivity of SKBR3 (sensitizer enhancement ratio [SER]: 1.21 at a surviving fraction of 0.5) and BT474 (SER: 1.26 at a surviving fraction of 0.5) cells and hindered the repair of DNA damage, as suggested by the prolongation of radiation-induced γH2AX foci and the down-regulation of phosphorylated DNA-dependent protein kinase, catalytic subunit (p-DNAPKcs). Increases in radiation-induced apoptosis and senescence were suggested to be the major modes of cell death induced by the combination of lapatinib and radiation. Furthermore, lapatinib did not radiosensitize a HER2- negative breast cancer cell line or normal human astrocytes.

These findings suggest that lapatinib can potentiate radiation-induced cell death in HER2-overexpressing breast cancer cells and may increase the efficacy of radiotherapy. A phase II clinical trial using lapatinib concurrently with whole-brain radiation therapy (WBRT) is currently being conducted.

Systemic Treatment Options for HER2-Positive Breast Cancer Patients with Brain Metastases beyond Trastuzumab: A Literature Review

BACKGROUND

The incidence of brain metastases (BM) in breast cancer patients has increased. Many retrospective analyses have shown that first-line treatment with trastuzumab prolongs survival in patients with HER2-positive BM. In contrast, the evidence for other therapies targeting HER2 for patients with BM is rare.

METHODS

The aim of this review is to update the reader about current systemic treatment options in patients with HER2-positive metastatic breast cancer with BM who had already received trastuzumab. A literature search was performed in the PubMed database in June 2016. 30 relevant reports concerning the efficacy of trastuzumab emtansine (T-DM1), lapatinib and its combination with other cytotoxic agents, pertuzumab and novel HER2-targeting substances were identified.

RESULTS

There is limited but promising evidence for the use of T-DM1 and pertuzumab in the treatment of BM. Up to now, most reported studies used lapatinib as treatment of HER2-positive breast cancer with BM, a treatment with only a modest effect and a high toxicity profile. The combination of lapatinib with cytotoxic agents seems to result in better response rates.

CONCLUSION

Further prospective investigations are needed to investigate the efficacy of the established and novel HER2-targeting agents on BM in HER2-positive breast cancer patients.

Developmental therapeutics for patients with breast cancer and central nervous system metastasis: current landscape and future perspectives

Breast cancer is the second-leading cause of metastatic disease in the central nervous system (CNS). Recent advances in the biological understanding of breast cancer have facilitated an unprecedented increase of survival in a subset of patients presenting with metastatic breast cancer. Patients with HER2 positive (HER2+) or triple negative breast cancer are at highest risk of developing CNS metastasis, and typically experience a poor prognosis despite treatment with local and systemic therapies. Among the obstacles ahead in the realm of developmental therapeutics for breast cancer CNS metastasis is the improvement of our knowledge on its biological nuances and on the interaction of the blood–brain barrier with new compounds. This article reviews recent discoveries related to the underlying biology of breast cancer brain metastases, clinical progress to date and suggests rational approaches for investigational therapies.

Experimental Therapeutic Trial Design for Pediatric Brain Tumors

Pediatric brain tumors are the leading cause of cancer-related death during childhood. Since the first pediatric brain tumor clinical trials, the field has seen improved outcomes in some, but not all tumor types. In the past few decades, a number of promising new therapeutic agents have emerged, yet only a few of these agents have been incorporated into clinical trials for pediatric brain tumors. In this review, the authors discuss the process of and challenges in pediatric clinical trial design; this will allow for highly efficient and effective clinical trials with appropriate endpoints to ensure rapid and safe investigation of novel therapeutics for children with brain tumors.

Brain metastasis in human epidermal growth factor receptor 2-positive breast cancer: from biology to treatment

Overexpression of human epidermal growth factor receptor 2 (HER2) is found in about 20% of breast cancer patients. With treatment using trastuzumab, an anti-HER2 monoclonal antibody, systemic control is improved. Nonetheless, the incidence of brain metastasis does not be improved, rather seems to be increased in HER2-positive breast cancer. The mainstay treatment for brain metastases is radiotherapy. According to the number of metastatic lesions and performance status of patients, radiosurgery or whole brain radiotherapy can be performed. The concurrent use of a radiosensitizer further improves intracranial control. Due to its large molecular weight, trastuzumab has a limited ability to cross the blood-brain barrier. However, small tyrosine kinase inhibitors such as lapatinib, has been noted to be a promising agent that can be used as a radiosensitizer to affect HER2-positive breast cancer. This review will outline general management of brain metastases and will focus on preclinical findings regarding the radiosensitizing effect of small molecule HER2 targeting agents.

Brain metastasis in breast cancer: a comprehensive literature review

This comprehensive review provides information on epidemiology, size, grade, cerebral localization, clinical symptoms, treatments, and factors associated with longer survival in 14,599 patients with brain metastasis from breast cancer; the molecular features of breast cancers most likely to develop brain metastases and the potential use of these predictive molecular alterations for patient management and future therapeutic targets are also addressed. The review covers the data from 106 articles representing this subject in the era of modern neuroimaging (past 35 years). The incidence of brain metastasis from breast cancer (24 % in this review) is increasing due to advances in both imaging technologies leading to earlier detection of the brain metastases and introduction of novel therapies resulting in longer survival from the primary breast cancer. The mean age at the time of breast cancer and brain metastasis diagnoses was 50.3 and 48.8 years respectively. Axillary node metastasis was noted in 32.8 % of the patients who developed brain metastasis. The median time intervals between the diagnosis of breast cancer to identification of brain metastasis and from identification of brain metastasis to death were 34 and 15 months, respectively. The most common symptoms experienced in patients with brain metastasis consisted of headache (35 %), vomiting (26 %), nausea (23 %), hemiparesis (22 %), visual changes (13 %) and seizures (12 %). A majority of the patients had multiple metastases (54.2 %). Cerebellum and frontal lobes were the most common sites of metastasis (33 and 16 %, respectively). Of the primary tumors for which biomarkers were recorded, 37 % were estrogen receptor (ER)+, 41 % ER-, 36 % progesterone receptor (PR)+, 34 % PR-, 35 % human epithelial growth factor receptor 2 (HER2)+, 41 % HER2-, 27 % triple negative and 18 % triple positive (TP). Treatment in most patients consisted of a multimodality approach often with two or more of the following: whole brain radiation therapy (52 %), chemotherapy (51 %), stereotactic radiosurgery (20 %), surgical resection (14 %), trastuzumab (39 %) for HER2 positive tumors, and hormonal therapy (34 %) for ER and/or PR positive tumors. Factors that had an impact on prognosis included grade and size of the tumor, multiple metastases, presence of extra-cranial metastasis, triple negative or HER2+ biomarker status, and high Karnovsky score. Novel therapies such as application of agents to reduce tumor angiogenesis or alter permeability of the blood brain barrier are being explored with preliminary results suggesting a potential to improve survival after brain metastasis. Other potential therapies based on genetic alterations in the tumor and the microenvironment in the brain are being investigated; these are briefly discussed.

Profound prevention of experimental brain metastases of breast cancer by temozolomide in an MGMT-dependent manner

PURPOSE

Brain metastases of breast cancer cause neurocognitive damage and are incurable. We evaluated a role for temozolomide in the prevention of brain metastases of breast cancer in experimental brain metastasis models.

EXPERIMENTAL DESIGN

Temozolomide was administered in mice following earlier injection of brain-tropic HER2-positive JIMT-1-BR3 and triple-negative 231-BR-EGFP sublines, the latter with and without expression of O(6)-methylguanine-DNA methyltransferase (MGMT). In addition, the percentage of MGMT-positive tumor cells in 62 patient-matched sets of breast cancer primary tumors and resected brain metastases was determined immunohistochemically.

RESULTS

Temozolomide, when dosed at 50, 25, 10, or 5 mg/kg, 5 days per week, beginning 3 days after inoculation, completely prevented the formation of experimental brain metastases from MGMT-negative 231-BR-EGFP cells. At a 1 mg/kg dose, temozolomide prevented 68% of large brain metastases, and was ineffective at a dose of 0.5 mg/kg. When the 50 mg/kg dose was administered beginning on days 18 or 24, temozolomide efficacy was reduced or absent. Temozolomide was ineffective at preventing brain metastases in MGMT-transduced 231-BR-EGFP and MGMT-expressing JIMT-1-BR3 sublines. In 62 patient-matched sets of primary breast tumors and resected brain metastases, 43.5% of the specimens had concordant low MGMT expression, whereas in another 14.5% of sets high MGMT staining in the primary tumor corresponded with low staining in the brain metastasis.

CONCLUSIONS

Temozolomide profoundly prevented the outgrowth of experimental brain metastases of breast cancer in an MGMT-dependent manner. These data provide compelling rationale for investigating the preventive efficacy of temozolomide in a clinical setting.