The efficacy of lapatinib in metastatic breast cancer with HER2 non-amplified primary tumors and EGFR positive circulating tumor cells: a proof-of-concept study

The Diversity of Liquid Biopsies and Their Potential in Breast Cancer Management

Analyzing blood as a so-called liquid biopsy in breast cancer (BC) patients has the potential to adapt therapy management. Circulating tumor cells (CTCs), extracellular vesicles (EVs), cell-free DNA (cfDNA) and other blood components mirror the tumoral heterogeneity and could support a range of clinical decisions. Multi-cancer early detection tests utilizing blood are advancing but are not part of any clinical routine yet. Liquid biopsy analysis in the course of neoadjuvant therapy has potential for therapy (de)escalation.Minimal residual disease detection via serial cfDNA analysis is currently on its way. The prognostic value of blood analytes in early and metastatic BC is undisputable, but the value of these prognostic biomarkers for clinical management is controversial. An interventional trial confirmed a significant outcome benefit when therapy was changed in case of newly emerging cfDNA mutations under treatment and thus showed the clinical utility of cfDNA analysis for therapy monitoring. The analysis of PIK3CA or ESR1 variants in plasma of metastatic BC patients to prescribe targeted therapy with alpesilib or elacestrant has already arrived in clinical practice with FDA-approved tests available and is recommended by ASCO. The translation of more liquid biopsy applications into clinical practice is still pending due to a lack of knowledge of the analytes' biology, lack of standards and difficulties in proving clinical utility.

Potential risk of drug-drug interactions of ponatinib via inhibition against human UDP-glucuronosyltransferases

Ponatinib is an efficient oral tyrosine kinase inhibitor (TKI) for T315I-positive Ph + ALL and T315I-positive chronic myeloid leukemia (CML) or BCR-ABL when no other TKIs can be prescribed. In this research, we evaluated the inhibitory effects of ponatinib on human recombinant UDP-glucuronosyltransferases (UGTs) and predicted the magnitude of potential drug-drug interaction (DDI) risk of co-treatment with ponatinib and UGTs substrates by using in vitro-in vivo extrapolation (IVIVE) method. Our study presented that ponatinib showed a broad-spectrum inhibition against UGTs. Particularly, ponatinib exhibited potent inhibitory effects towards UGT1A7, UGT1A1, and UGT1A9 with IC50 values of 0.37, 0.41, and 0.89 μM, respectively, which might lead to clinically significant DDI.

Multiparametric Circulating Tumor Cell Analysis to Select Targeted Therapies for Breast Cancer Patients

Simple Summary

Liquid biopsies may act as a dynamic tool for identification of targets for precision therapy while circumventing limitations of tissue biopsies. In opposite to most liquid biopsy-related studies that analyze limited patient material for only one parameter, this study is based on a longitudinal and multiparametric analysis of circulating tumor cells (CTCs). A metastatic breast cancer patient was followed over a period of three years and analyses of the genome, RNA profiling, and in vitro drug testing on cultured CTCs were performed in a unique manner. We show that combining the strengths of multiple technologies for analysis yielded maximum information on the ongoing disease and, eventually, allowed choosing an effective therapy, which led to a massive reduction in CTC numbers. This approach provides a concept for future detailed longitudinal and multiparametric CTC analyses.

Abstract

Background: The analysis of liquid biopsies, e.g., circulating tumor cells (CTCs) is an appealing diagnostic concept for targeted therapy selection. In this proof-of-concept study, we aimed to perform multiparametric analyses of CTCs to select targeted therapies for metastatic breast cancer patients. Methods: First, CTCs of five metastatic breast cancer patients were analyzed by whole exome sequencing (WES). Based on the results, one patient was selected and monitored by longitudinal and multiparametric liquid biopsy analyses over more than three years, including WES, RNA profiling, and in vitro drug testing of CTCs. Results: Mutations addressable by targeted therapies were detected in all patients, including mutations that were not detected in biopsies of the primary tumor. For the index patient, the clonal evolution of the tumor cells was retraced and resistance mechanisms were identified. The AKT1 E17K mutation was uncovered as the driver of the metastatic process. Drug testing on the patient’s CTCs confirmed the efficacy of drugs targeting the AKT1 pathway. During a targeted therapy chosen based on the CTC characterization and including the mTOR inhibitor everolimus, CTC numbers dropped by 97.3% and the disease remained stable as determined by computer tomography/magnetic resonance imaging. Conclusion: These results illustrate the strength of a multiparametric CTC analysis to choose and validate targeted therapies to optimize cancer treatment in the future. Furthermore, from a scientific point of view, such studies promote the understanding of the biology of CTCs during different treatment regimens.

Enumeration and molecular characterization of circulating tumor cells as an innovative tool for companion diagnostics in breast cancer

INTRODUCTION

Circulating tumor cells (CTC) and more recently, CTC clusters are implicated as a fundamental mechanism by which tumor cells break away from the primary site and travel to distant sites. Enumeration of CTC and CTC clusters represents a new approach to prognosis, prediction, and response to therapy in patients with early and metastatic breast cancer. Several recent studies have shown the predictive importance of monitoring CTCs levels in progression-free and overall survival in breast cancer patients. This review will focus on CTC enumeration and characterization in breast cancers.

AREAS COVERED

We will provide a historical perspective and clinical background of CTC detection in peripheral blood. The current methodologies for studying CTCs and newer technologies for CTC detection will be reviewed together with the current state of the art of CTCs as a biomarker in risk stratification and prognostication in breast cancers.

EXPERT OPINION

Currently, there is an FDA approved CTC assessment method for clinical use. While CTC enumeration, is a marker for prognostication and survival, molecular characterization of CTC, may be more accurate in monitoring response to treatment due to tumor heterogeneity rather than the tumor phenotype at the primary or metastatic sites.

Circulating Tumour Cells in Predictive Molecular Pathology: Focus on Drug-Sensitive Assays and 3D Culture

Molecular cytopathology is a rapidly evolving field of cytopathology that provides biological information about the response to personalised therapy and about the prognosis of neoplasms diagnosed on cytological samples. Biomarkers such as circulating tumour cells and circulating tumour DNA are increasingly being evaluated in blood and in other body fluids. Such liquid biopsies are non-invasive, repeatable, and feasible also in patients with severe comorbidities. However, liquid biopsy may be challenging due to a low concentration of biomarkers. In such cases, biomarkers can be detected with highly sensitive molecular techniques, which in turn should be validated and integrated in a complex algorithm that includes tissue-based molecular assessments. The aim of this review is to provide the cytopathologist with practical information that is relevant to daily practice, particularly regarding the emerging role of circulating tumour cells in the field of predictive molecular pathology.

In vitro UGT1A1 inhibition by tyrosine kinase inhibitors and association with drug-induced hyperbilirubinemia

PURPOSE

Hyperbilirubinemia has been observed in patients treated with tyrosine kinase inhibitor (TKI) drugs. Therefore, it would be beneficial to understand whether there is a relationship between inhibition of uridine-5'-diphosphate glucuronosyltransferase (UGT) 1A1 activity and observed bilirubin elevations in TKI drug-treated patients. UGT1A1 is responsible for the glucuronidation of bilirubin which leads to its elimination in the bile.

METHODS

To examine this question, an in vitro glucuronidation assay was developed to determine the inhibitory effect of TKI drugs employing human liver microsomes (HLM) with varying UGT1A1 activity. Utilizing β-estradiol as the UGT1A1 probe substrate, 20 TKI drugs were evaluated at concentrations that represent clinical plasma levels. Adverse event reports were searched to generate an empirical Bayes geometric mean (EGBM) score for clinical hyperbilirubinemia with the TKI drugs.

RESULTS

Erlotinib, nilotinib, regorafenib, pazopanib, sorafenib and vemurafenib had IC₅₀ values that were lower than their clinical steady-state C_max concentrations. These TKI drugs had high incidences of hyperbilirubinemia and higher EBGM scores. The IC₅₀ values and C_max/IC₅₀ ratios correlated well with EBGM scores for hyperbilirubinemia (P < 0.005). For the TKI drugs with higher incidence of hyperbilirubinemia in Gilbert syndrome patients, who have reduced UGT1A1 activity, six of eight had smaller ratios in the low UGT1A1 activity microsomes than the wild-type microsomes for drugs, indicating greater sensitivity to the drugs in this phenotype.

CONCLUSIONS

These results suggest that in vitro UGT1A1 inhibition assays have the potential to predict clinical hyperbilirubinemia.

Circulating and disseminated tumor cells: diagnostic tools and therapeutic targets in motion

Enumeration of circulating tumor cells (CTCs) in peripheral blood with the gold standard CellSearchTM has proven prognostic value for tumor recurrence and progression of metastatic disease. Therefore, the further molecular characterization of isolated CTCs might have clinical relevance as liquid biopsy for therapeutic decision-making and to monitor disease progression. The direct analysis of systemic cancer appears particularly important in view of the known disparity in expression of therapeutic targets as well as epithelial-to-mesenchymal transition (EMT)-based heterogeneity between primary and systemic tumor cells, which all substantially complicate monitoring and therapeutic targeting at present. Since CTCs are the potential precursor cells of metastasis, their in-depth molecular profiling should also provide a useful resource for target discovery. The present review will discuss the use of systemically spread cancer cells as liquid biopsy and focus on potential target antigens.

Clinical applications of the CellSearch platform in cancer patients

The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive "liquid biopsy". While the association of CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.

Clinical indications for, and the future of, circulating tumor cells

Circulating tumor cells (CTCs) are cells that have detached from the primary tumor and entered circulation with potential to initiate a site of metastasis. Currently, CTC detection using CellSearch is cleared by the Food and Drug Administration for monitoring metastatic breast, prostate, and colorectal cancers as a prognostic biomarker for progression-free and overall survival. Accumulating evidence suggests CTCs have similar prognostic value in other metastatic and non-metastatic settings. Current research efforts are focused on extending the utility of CTCs beyond a prognostic biomarker to help guide clinical decision-making. These include using CTCs as a screening tool for diagnosis, liquid biopsy for molecular profiling, predictive biomarker to specific therapies, and monitoring tool to assess response and guide changes to treatment. CTCs have unique advantages vs circulating tumor DNA in this endeavor. Indications for CTCs in daily practice will expand as isolation techniques improve and clinical studies validating their utility continue to grow.

Cardiac toxicities of lapatinib in patients with breast cancer and other HER2-positive cancers: a meta-analysis

PURPOSE

Lapatinib is a tyrosine kinase inhibitor that targets the human epidermal growth factor receptor 2 (HER2) and the epidermal growth factor receptor (EGFR/HER1), and there are concerns about its cardiac toxicity. Recent studies of lapatinib have reported cardiac adverse events; however, the results have been inconsistent among the studies. The aim of our study was to estimate the cardiac toxicity of lapatinib in patients with breast cancer and other HER2-positive cancers.

METHODS

To evaluate the cardiotoxicity of lapatinib, the results of previous studies were quantitatively integrated using meta-analysis. Forty-five articles regarding cardiac adverse events, including left ventricular dysfunction, left ventricular ejection fraction (LVEF) decrease, arrhythmia, and other cardiac adverse events, were assessed. As a subgroup analysis in patients with breast cancer, 26 studies of lapatinib-induced cardiac adverse events were assessed.

RESULTS

The overall incidence of cardiac adverse events was 2.70% (95% confidence interval [CI] 1.60-4.50%). The incidences of left ventricular dysfunction and LVEF decrease were 1.60% (95% CI 1.30-2.00%) and 2.20% (95% CI 1.30-3.60%), respectively. The overall incidence of cardiac adverse events was 3.00% (95% CI 1.50-6.10%) in patients with breast cancer, which was marginally higher than the rate in patients with all type of cancers.

CONCLUSION

The overall incidence of lapatinib-induced cardiac toxicity was relatively low based on an indirect comparison with trastuzumab. However, careful monitoring of cardiac toxicity is still needed when patients are treated with lapatinib because the related risk factors have not been clearly identified.

Circulating tumor cells: clinical validity and utility

Circulating tumor cells (CTCs) are rare tumor cells and have been investigated as diagnostic, prognostic and predictive biomarkers in many types of cancer. Although CTCs are not currently used in clinical practice, CTC studies have accumulated a high level of clinical validity, especially in breast, lung, prostate and colorectal cancers. In this review, we present an overview of the current clinical validity of CTCs in metastatic and non-metastatic disease, and the main concepts and studies investigating the clinical utility of CTCs. In particular, this review will focus on breast, lung, colorectal and prostate cancer. Three major topics concerning the clinical utility of CTC are discussed-(1) treatment based on CTCs used as liquid biopsy, (2) treatment based on CTC count or CTC variations, and (3) treatment based on CTC biomarker expression. A summary of published or ongoing phase II and III trials is also presented.

Pattern of metastatic spread and subcategories of breast cancer

PURPOSE

The development of metastases is the most aggressive attribute of breast cancer. In this retrospective multicenter study, we evaluated if and how the different pathological breast cancer subtypes influence the spreading of tumor cells, the development of metastasis and the survival of breast cancer patients.

METHODS

This retrospective German multicenter study is based on the BRENDA collective including 9625 breast cancer patients treated in the adjuvant setting. We used the χ ² tests for the analysis of the categorical variables between groups of patients with different sites of metastasis. Survival distributions and median survival times were estimated using the Kaplan-Meier product-limit method. The log-rank test was applied to compare survival rates. The Cox proportional hazards model was used to estimate the hazard ratio and confidence intervals.

RESULTS

886 women developed metastases during a time interval of 53 months after primary diagnosis. Luminal A tumor patients were more likely to get bone metastases than lung, liver or CNS metastases. Patients with a triple-negative subtype were, however, the least affected by metastasis in the skeleton. They were most likely to develop visceral metastases. Location, numbers of metastases herein and the subtype influenced the overall survival (OAS). Altogether, the best OAS was found in patients with the luminal A subtype, the worst in patients with the triple-negative subtype.

CONCLUSIONS

Knowledge of the typical metastatic pattern of the subtypes of breast cancer will help to personalize therapeutic options and follow-up examinations of cancer patients.

Molecular Testing and the Pathologist's Role in Clinical Trials of Breast Cancer

Molecular characterization of breast cancer is pivotal for identifying new molecular targets and determining the appropriate treatment choices. Advances in molecular profiling technology have given greater insight into this heterogeneous disease, over and above hormone receptor and human epidermal growth factor receptor 2 status. Agents targeting recently characterized molecular biomarkers are under clinical development; the success of these targeted agents is likely to depend on identifying the patient population most likely to benefit. Therefore, clinical trials of breast cancer often require prescreening for, or stratification by, relevant molecular markers or exploratory analyses of biomarkers that can predict or monitor the response to treatment. Consequently, the role of the pathologist has become increasingly important. The key considerations for pathologists include tissue availability, ownership of archival tissue, type of diagnostic/biomarker test required, method of sample processing, concordance between different tests and testing centers, and tumor heterogeneity. In the present review, we explore how pathology is used in current clinical trials of breast cancer and describe the various technologies available for molecular testing. Furthermore, the factors required for the successful application of pathology in clinical trials of breast cancer and the issues that can arise and how these can be circumvented are discussed.

The promise of liquid biopsy in cancer: a clinical perspective

The clinical utility of liquid biopsy in cancer treatment will increase as circulating tumor cells (CTCs) analysis move from the enumeration to the real-time measurement of tumor characteristics. Intratumor heterogeneity is becoming increasingly recognized as a major drawback to the shift to personalized medicine. Spatial and temporal heterogeneity might be reflected by the serial assessment of CTCs. Indeed, the developing technologies for CTCs analysis now allow digital genomic and next-generation sequencing approaches, able to differentiate molecular subtypes of the disease and to monitor genetic variation over time. The liquid biopsy of cancer might offer a real-time assessment of tumor biology, providing the opportunity to serially evaluate patients most likely to benefit from targeted drugs based on a dynamic characterization of the disease at the molecular level. Although hurdles remain before liquid biopsy is seen in routine clinical practice, the information derived from CTCs may facilitate the real-time identification of actionable mutations in cancer leading the way toward personalized medicine.

The use of circulating biomarkers in early clinical trials in patients with cancer

The development of targeted therapies has changed the approach to early oncological clinical trial design. Identification of patient populations most likely to derive benefit and the biologically effective dose are now as important as determination of the maximum tolerated dose. Completion of the 'pharmacological audit trail' highlights drugs most likely to progress through to license, so resources can be allocated appropriately. Key to the success of this changing model is the validation/qualification of circulating biomarkers. These might provide a readily accessible and dynamic picture of drug effect, tumor response and toxicity with minimum risk to patients. This review article examines circulating biomarkers currently used in early oncological clinical trials. It considers the evidence for their employment, limitations and challenges for future development.

Efficacy of Lapatinib in Therapy-Resistant HER2-Positive Circulating Tumor Cells in Metastatic Breast Cancer

BACKGROUND

To evaluate the efficacy of lapatinib, a dual EGFR and HER2 tyrosine kinase inhibitor, in therapy-resistant HER2-positive CTCs in metastatic breast cancer (MBC).

PATIENTS AND METHODS

Patients with MBC and HER2-positive CTCs despite disease stabilization or response to prior therapy, received lapatinib 1500 mg daily in monthly cycles, till disease progression or CTC increase. CTC monitoring was performed by immunofluorescent microscopy using cytospins of peripheral blood mononuclear cells (PBMCs) double stained for HER2 or EGFR and cytokeratin.

RESULTS

A total of 120 cycles were administered in 22 patients; median age was 62.5 years, 15 (68.2%) patients were post-menopausal and 20 (90.1%) had HER2-negative primary tumors. At the end of the second course, HER2-positive CTC counts decreased in 76.2% of patients; the median number of HER2-positive CTCs/patient also declined significantly (p = 0.013), however the decrease was significant only among patients presenting disease stabilization (p = 0.018) but not among those with disease progression during lapatinib treatment. No objective responses were observed. All CTC-positive patients harbored EGFR-positive CTCs on progression compared to 62.5% at baseline (p = 0.054). The ratio of EGFR-positive CTCs/total CTCs detected in all patients increased from 17.1% at baseline to 37.6% on progression, whereas the mean percentage of HER2-negative CTCs/patient increased from 2.4% to 30.6% (p = 0.03).

CONCLUSIONS

The above results indicate that lapatinib is effective in decreasing HER2-positive CTCs in patients with MBC irrespectively of the HER2 status of the primary tumor and imply the feasibility of monitoring the molecular changes on CTCs during treatment with targeted agents.

TRIAL REGISTRATION

Clinical trial.gov NCT00694252.

CTC enumeration and characterization: moving toward personalized medicine

The primary cause of tumor-related death in breast cancer (BC) is still represented by distant metastasization. The dissemination of tumor cells from the primary tumor to distant sites through bloodstream cannot be early detected by standard imaging methods. The enumeration of circulating tumor cells (CTCs) represents an effective prognostic and predictive biomarker, which is able to monitor efficacy of adjuvant therapies, detect early development of (micro)metastases and at last, assess therapeutic responses of advanced disease earlier than traditional imaging methods. Moreover, since repeated tissue biopsies are invasive, costly and not always feasible, the assessment of tumor characteristics on CTCs, by a peripheral blood sample as a 'liquid biopsy', represents an attractive opportunity. The implementation of molecular and genomic characterization of CTCs could contribute to improve the treatment selection and thus, to move toward more personalized treatments. This review describes the current state of the art on CTC detection strategies, the evidence to demonstrate their clinical validity, and their potential impact for both future clinical trial design and, decision-making process in our daily practice.

Can biomarker assessment on circulating tumor cells help direct therapy in metastatic breast cancer?

Circulating tumor cell (CTC) count has prognostic significance in metastatic breast cancer, but the predictive utility of CTCs is uncertain. Molecular studies on CTCs have often been limited by a low number of CTCs isolated from a high background of leukocytes. Improved enrichment techniques are now allowing molecular characterisation of single CTCs, whereby molecular markers on single CTCs may provide a real-time assessment of tumor biomarker status from a blood test or “liquid biopsy”, potentially negating the need for a more invasive tissue biopsy. The predictive ability of CTC biomarker analysis has predominantly been assessed in relation to HER2, with variable and inconclusive results. Limited data exist for other biomarkers, such as the estrogen receptor. In addition to the need to define and validate the most accurate and reproducible method for CTC molecular analysis, the clinical relevance of biomarkers, including gain of HER2 on CTC after HER2 negative primary breast cancer, remains uncertain. This review summarises the currently available data relating to biomarker evaluation on CTCs and its role in directing management in metastatic breast cancer, discusses limitations, and outlines measures that may enable future development of this approach.

Recent advances in the molecular characterization of circulating tumor cells

Although circulating tumor cells (CTCs) were first observed over a century ago, lack of sensitive methodology precluded detailed study of these cells until recently. However, technological advances have now facilitated the identification, enumeration, and characterization of CTCs using a variety of methods. The majority of evidence supporting the use of CTCs in clinical decision-making has been related to enumeration using the CellSearch® system and correlation with prognosis. Growing evidence also suggests that CTC monitoring can provide an early indication of patient treatment response based on comparison of CTC levels before and after therapy. However, perhaps the greatest potential that CTCs hold for oncology lies at the level of molecular characterization. Clinical treatment decisions may be more effective if they are based on molecular characteristics of metastatic cells rather than on those of the primary tumor alone. Molecular characterization of CTCs (which can be repeatedly isolated in a minimally invasive fashion) provides the opportunity for a "real-time liquid biopsy" that allows assessment of genetic drift, investigation of molecular disease evolution, and identification of actionable genomic characteristics. This review focuses on recent advances in this area, including approaches involving immunophenotyping, fluorescence in situ hybridization (FISH), multiplex RT-PCR, microarray, and genomic sequencing.