Systemic treatment of HER2-positive metastatic breast cancer: A systematic review

Single-cell RNA sequencing to explore cancer-associated fibroblasts heterogeneity: "Single" vision for "heterogeneous" environment

Cancer-associated fibroblasts (CAFs), a phenotypically and functionally heterogeneous stromal cell, are one of the most important components of the tumour microenvironment. Previous studies have consolidated it as a promising target against cancer. However, variable therapeutic efficacy-both protumor and antitumor effects have been observed not least owing to the strong heterogeneity of CAFs. Over the past 10 years, advances in single-cell RNA sequencing (scRNA-seq) technologies had a dramatic effect on biomedical research, enabling the analysis of single cell transcriptomes with unprecedented resolution and throughput. Specifically, scRNA-seq facilitates our understanding of the complexity and heterogeneity of diverse CAF subtypes. In this review, we discuss the up-to-date knowledge about CAF heterogeneity with a focus on scRNA-seq perspective to investigate the emerging strategies for integrating multimodal single-cell platforms. Furthermore, we summarized the clinical application of scRNA-seq on CAF research. We believe that the comprehensive understanding of the heterogeneity of CAFs form different visions will generate innovative solutions to cancer therapy and achieve clinical applications.

The Role of the Tumor Microenvironment in Triple-Positive Breast Cancer Progression and Therapeutic Resistance

Breast cancer (BRCA) is a highly heterogeneous systemic disease. It is ranked first globally in the incidence of new cancer cases and has emerged as the primary cause of cancer-related death among females. Among the distinct subtypes of BRCA, triple-positive breast cancer (TPBC) has been associated with increased metastasis and invasiveness, exhibiting greater resistance to endocrine therapy involving trastuzumab. It is now understood that invasion, metastasis, and treatment resistance associated with BRCA progression are not exclusively due to breast tumor cells but are from the intricate interplay between BRCA and its tumor microenvironment (TME). Accordingly, understanding the pathogenesis and evolution of the TPBC microenvironment demands a comprehensive approach. Moreover, addressing BRCA treatment necessitates a holistic consideration of the TME, bearing significant implications for identifying novel targets for anticancer interventions. This review expounds on the relationship between critical cellular components and factors in the TPBC microenvironment and the inception, advancement, and therapeutic resistance of breast cancer to provide perspectives on the latest research on TPBC.

The adverse effects of trastuzumab-containing regimes as a therapy in breast cancer: A piggy-back systematic review and meta-analysis

BACKGROUND

Trastuzumab is a valuable therapy option for women with ERBB2(HER2)+ breast cancer tumours, often used in combination with chemotherapy and alongside other therapies. It is known to have adverse effects, but these have proved difficult to separate from the effects of other concurrent therapies patients are usually taking. This study aims to assess the adverse effects specifically attributable to trastuzumab, and whether they vary by patient subgroup or concurrent therapies.

METHODS

As registered on PROSPERO (CRD42019146541), we used previous systematic reviews as well as the clinicaltrials.gov registry to identify randomised controlled trials in breast cancer which compared treatment regimes with and without trastuzumab. Neoadjuvant, adjuvant and metastatic settings were examined. Data was extracted from those which had, as of July 2022, reported adverse events. Risk of bias was assessed using ROB2. Primary outcomes were adverse events of any type or severity (excluding death). A standard random-effects meta-analysis was performed for each outcome independently. In order to ascertain whether adverse effects differed by individual factors such as age or tumour characteristics, or by use of trastuzumab concurrently with hormone therapy, we examined individual-level patient data for one large trial, HERA.

RESULTS

79 relevant trials were found, of which 20 contained comparable arms of trastuzumab-containing therapy and corresponding matched therapy without trastuzumab. This allowed a comparison of 8669 patients receiving trastuzumab versus 9556 receiving no trastuzumab, which gave a list of 25 statistically and clinically significant adverse effects related to trastuzumab alone: unspecified pain, asthenia, nasopharyngitis, skin disorders (mainly rash), dyspepsia, paraesthesia, infections (often respiratory), increased lacrimation, diarrhoea, myalgia, oedema (limb/peripheral), fever, nose bleeds, cardiac events, insomnia, cough, back pain, dyspnoea, chills, dizziness or vertigo, hypertension, congestive heart failure, increased levels of aspartate aminotransferase, gastrointestinal issues and dehydration. Analysis of individual patient-level data from 5102 patients suggested that nausea is slightly more likely for women taking trastuzumab who are ER+ /also taking hormone therapy than for those who are ER-/not taking hormone therapy; no other potential treatment-subgroup interactions were detected. We found no evidence for significantly increased rates of neutropenia, anaemia or lymphopenia in patients on trastuzumab-containing regimes compared to those on comparable regimes without trastuzumab.

CONCLUSIONS

This meta-analysis should allow clinicians and patients to better identify and quantify the potential adverse effects of adding trastuzumab to their treatment regime for breast cancer, and hence inform their decision-making. However, limitations include serious risk of bias due to heterogeneity in reporting of the outcomes and the open-label nature of the trials.

Comparative review of pharmacological therapies in individuals with HER2-positive advanced breast cancer with focus on hormone receptor subgroups

Breast cancer is the fifth leading cause of cancer-related deaths worldwide. The randomized controlled trials (RCTs) of targeted therapies in human epidermal receptor 2 (HER2)-positive advanced breast cancer (ABC) have provided an evidence base for regulatory and reimbursement agencies to appraise the use of cancer therapies in clinical practice. However, a subset of these patients harbor additional biomarkers, for example, a positive hormone receptor status that may be more amenable to therapy and improve overall survival (OS). This review seeks to explore the reporting of evidence for treatment effects by the hormone receptor status using the RCT evidence of targeted therapies for HER2-positive ABC patients. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed to identify published RCTs. Extracted data were synthesized using network meta-analysis to obtain the relative effects of HER2-positive-targeted therapies. We identified a gap in the reporting of the effectiveness of therapies by the hormone receptor status as only 15 out of 42 identified RCTs reported hormone receptor subgroup analyses; the majority of which reported progression-free survival but not OS or the overall response rate. In conclusion, we recommend that future trials in ABC should report the effect of cancer therapies in hormone receptor subgroups for all outcomes.

Understanding breast cancer heterogeneity through non-genetic heterogeneity

Intricacy in treatment and diagnosis of breast cancer has been an obstacle due to genotype and phenotype heterogeneity. Understanding of non-genetic heterogeneity mechanisms along with considering role of genetic heterogeneity may fill the gaps in landscape painting of heterogeneity. The main factors contribute to non-genetic heterogeneity including: transcriptional pulsing/bursting or discontinuous transcriptions, stochastic partitioning of components at cell division and various signal transduction from tumor ecosystem. Throughout this review, we desired to provide a conceptual framework focused on non-genetic heterogeneity, which has been intended to offer insight into prediction, diagnosis and treatment of breast cancer.

Recent advances in understanding tumor stroma-mediated chemoresistance in breast cancer

Although solid tumors comprise malignant cells, they also contain many different non-malignant cell types in their micro-environment. The cellular components of the tumor stroma consist of immune and endothelial cells combined with a heterogeneous population of stromal cells which include cancer-associated fibroblasts. The bi-directional interactions between tumor and stromal cells therefore substantially affect tumor cell biology.Herein, we discuss current available information on these interactions in breast cancer chemo-resistance. It is acknowledged that stromal cells extrinsically alter tumor cell drug responses with profound consequences for therapy efficiency, and it is therefore essential to understand the molecular mechanisms which contribute to these substantial alterations because they provide potential targets for improved cancer therapy. Although breast cancer patient survival has improved over the last decades, chemo-resistance still remains a significant obstacle to successful treatment.Appreciating the important experimental evidence of mesenchymal stromal cells and cancer-associated fibroblast involvement in breast cancer clinical practice can therefore have important therapeutic implications.

More than just the median: Calculating survival times for patients with HER2 positive, metastatic breast cancer using data from recent randomised trials

OBJECTIVES

To estimate worst-case, typical and best-case scenarios for survival as a communication aid for managing patients with HER2-positive metastatic breast cancer (MBC) starting HER2-targeted therapies.

METHODS

We sought randomised trials of HER2-targeted therapies and recorded the following percentiles (representative scenarios) from each OS curve: 90th (worst-case), 75th (lower-typical), 50th (median), 25th (upper-typical) and 10th (best-case). We then tested whether we could estimate these percentiles for each OS curve by multiplying its median by four simple multiples: 0.25 (to derive the 90th percentile), 0.5 (75th), 2 (25th) and 3 (10th). Estimates were deemed accurate if within 0.75-1.33 times the actual value.

RESULTS

We identified 15 trials with 4798 patients. For first-line, single-agent HER2-targeted therapy (15 treatment groups), the median (interquartile range [IQR]) for median OS was 33.3 months (29.1-38.4), and for each percentile was: 90th 9.5 months (7.7-11.0); 75th 19.2 months (16.4-20.8); and 25th 50.6 months (47.1-63.3). The 10th percentile was unavailable for all treatment groups. For first-line dual HER2-targeted therapy (1 treatment group), the median OS was 56.5 months. Simple multiples of the median OS accurately estimated the: 90th percentile in 79%; 75th percentile in 100%; and 25th percentile in 89% of OS curves.

CONCLUSIONS

Surprisingly little is known of survival beyond the median for HER2-positive MBC. Longer trial follow-up is required to help clinicians estimate and explain the best-case scenario. Simple multiples of the median OS provide a reasonable framework for estimating then explaining survival times to patients.

Management of patients treated with pertuzumab in the Australian clinical practice setting

AIM

Treatment with pertuzumab-trastuzumab-taxane combinations has become the international standard of care for patients with HER2-positive metastatic breast cancer. In this paper we discuss the practicalities of treating patients with this combination with a particular focus on treatment in the Australian setting.

METHOD

An expert panel was convened to discuss practical aspects for use of pertuzumab in the Australian clinical setting. The findings of this panel are reported in this article.

RESULTS

The combination of pertuzumab-trastuzumab-docetaxel has established efficacy in patients with HER2-positive metastatic breast cancer, prolonging progression-free and overall survival compared to trastuzumab-taxane combinations. In Australia, combinations of pertuzumab and trastuzumab with docetaxel or paclitaxel are reimbursed. Management of treatment related side-effects such as diarrhea, febrile neutropenia and neuropathy typically include dose reduction or switching taxane. Specific patients with poorer tolerance of chemotherapy such as the elderly or those from Asian backgrounds may require particular management strategies.

CONCLUSIONS

The advent of targeted therapies for women with metastatic HER2-positive breast cancer has markedly improved survival. Combinations of pertuzumab-trastuzumab and a taxane are the standard of care in patients with good performance status. Given prolongation of survival and the importance of quality of life endpoints, the treatment paradigm for patients with metastatic HER2-positive breast cancer is changing rapidly. Careful management of toxicities is required, and dose reduction or switching taxane may be necessary. Further research is required on the efficacy of pertuzumab combinations in patients with brain metastases, and on those who relapse quickly following adjuvant therapy.

Estimated Life-Years Saved in Women with HER2-Positive Metastatic Breast Cancer Receiving First-Line Trastuzumab and Pertuzumab in the United States

BACKGROUND

HER2 positive (HER2+) metastatic breast cancer (MBC) is associated with high mortality. Trastuzumab was approved for use in 1998, but the life-years saved from first-line use are unknown, as are the potential US population benefits from adding pertuzumab.

OBJECTIVES

The first aim was to estimate the number of life-years saved by using first-line trastuzumab between 1999 and 2013 in HER2+ women with MBC. In addition, based on these estimates, the second aim was to project the life-years that could be saved by adding pertuzumab to trastuzumab in first-line therapy.

METHODS

We constructed a simulation model accounting for incidence, testing rates, therapy utilization, and overall survival. The model was run for 1999 to 2013 (15 years) to estimate the life-years saved from using trastuzumab plus chemotherapy instead of chemotherapy alone. The model was also run from 2013 to 2027 (15 years) to project the life-years that might be saved by adding pertuzumab. Uncertainty was incorporated using Monte-Carlo methods.

RESULTS

The estimated number of women with HER2+ MBC varied over time, with the peak of 9700 in 2005 and the low of 7700 in 2018. The cumulative incremental life-years saved because of first-line trastuzumab use from 1999 to 2013 was estimated to be 156,413 (95% simulation interval 114,840-195,201). The projection for pertuzumab from 2013 to 2027 was 137,959 (95% simulation interval 56,011-225,069). Exploratory analyses of value showed that pertuzumab, trastuzumab, and chemotherapy is associated with a $1.10 billion gain compared with chemotherapy alone, and adding pertuzumab is associated with a $0.06 billion gain compared with trastuzumab with chemotherapy.

CONCLUSIONS

This simulation model suggests that substantial progress has been made in treating HER2+ women over the past 15 years, and the future may witness similar gains with the introduction of pertuzumab.

The impact of tumor stroma on drug response in breast cancer

In the last two decades the breast cancer mortality rate has steadily declined, in part, due to the availability of better treatment options. However, drug resistance still remains a major challenge. Resistance can be an inherent feature of breast cancer cells, but can also arise from the tumor microenvironment. This review aims to focus on the modulatory effect of the tumor microenvironment on the differing response of breast cancer subtypes to targeted drugs and chemotherapy.