HER2 heterogeneity and treatment response-associated profiles in HER2-positive breast cancer in the NCT02326974 clinical trial

BACKGROUNDHER2-targeting therapies have great efficacy in HER2-positive breast cancer, but resistance, in part due to HER2 heterogeneity (HET), is a significant clinical challenge. We previously described that in a phase II neoadjuvant trastuzumab emtansine (T-DM1) and pertuzumab (P) clinical trial in early-stage HER2-positive breast cancer, none of the patients with HER2-HET tumors had pathologic complete response (pCR).METHODSTo investigate cellular and molecular differences among tumors according to HER2 heterogeneity and pCR, we performed RNA sequencing and ERBB2 FISH of 285 pretreatment and posttreatment tumors from 129 patients in this T-DM1+P neoadjuvant trial. A subset of cases was also subject to NanoString spatial digital profiling.RESULTSPretreatment tumors from patients with pCR had the highest level of ERBB2 mRNA and ERBB signaling. HER2 heterogeneity was associated with no pCR, basal-like features, and low ERBB2 expression yet high ERBB signaling sustained by activation of downstream pathway components. Residual tumors showed decreased HER2 protein levels and ERBB2 copy number heterogeneity and increased PI3K pathway enrichment and luminal features. HET tumors showed minimal treatment-induced transcriptomic changes compared with non-HET tumors. Immune infiltration correlated with pCR and HER2-HET status.CONCLUSIONResistance mechanisms in HET and non-HET tumors are distinct. HER2-targeting antibodies have limited efficacy in HET tumors. Our results support the stratification of patients based on HET status and the use of agents that target downstream components of the ERBB signaling pathway in patients with HET tumors.TRIAL REGISTRATIONClinicalTrials.gov NCT02326974.FUNDINGThis study was funded by Roche and the National Cancer Institute.

Brassica-derived isothiocyanates as anticancer therapeutic agents and their nanodelivery

The isothiocyanates (ITCs) derived from the precursor glucosinolate molecules present in Brassica vegetables are bioactive organo-sulfur compounds with numerous pharmacologically important properties such as antioxidant, antiinflammatory, antimicrobial, and anticancer. Over the years, ITCs have been the focus of several research investigations associated with cancer treatment. Due to their potent chemo-preventive action, ITCs have been considered to be promising therapeutics for cancer therapy in place of the already existing conventional anticancer drugs. However, their wide spread use at the clinical stage is greatly restricted due to several factors such as low solubility in an aqueous medium, low bioavailability, low stability, and hormetic effect. To overcome these hindrances, nanotechnology can be exploited to develop nano-scale delivery systems that have the potential to enhance stability, and bioavailability and minimize the hermetic effect of ITCs.

Development of Tumor Markers for Breast Cancer Immunotherapy

Although breast cancer treatment has been developed remarkably in recent years, it remains the primary cause of death among women. Immune checkpoint blockade therapy has significantly altered the way breast cancer is treated, although not all patients benefit from the changes. At present, the most effective mechanism of immune checkpoint blockade application in malignant tumors is not clear and efficacy may be influenced by many factors, including host, tumor, and tumor microenvironment dynamics. Therefore, there is a pressing need for tumor immunomarkers that can be used to screen patients and help determine which of them would benefit from breast cancer immunotherapy. At present, no single tumor marker can predict treatment efficacy with sufficient accuracy. Multiple markers may be combined to more accurately pinpoint patients who will respond favorably to immune checkpoint blockade medication. In this review, we have examined the breast cancer treatments, developments in research on the role of tumor markers in maximizing the clinical efficacy of immune checkpoint inhibitors, prospects for the identification of novel therapeutic targets, and the creation of individualized treatment plans. We also discuss how tumor markers can provide guidance for clinical practice.

A comprehensive update of hormone-related pharmacokinetic variations associated with breast cancer drugs

INTRODUCTION

Drugs available for the treatment of breast cancer are increasing, yielding improved oncological outcomes. The efficacy and safety of anticancer drugs significantly depend on pharmacokinetic profiles, which could be influenced by several factors, such as sex hormones.

AREAS COVERED

This article discusses the potential hormone-related pharmacokinetic influences on novel breast cancer pharmacotherapies.

EXPERT OPINION

Recently approved drugs for the treatment of breast cancer belong to different classes, each with unique pharmacokinetic profile. The impact of hormones, such as estrogen and progesterone, may occur at different steps of drug metabolism. Key effects of sex hormones ha ve been reported on multidrug-resistant transporters and enzymes involved in the liver metabolism of drugs, such as cytochromes. Nevertheless, no data is currently available to establish hormone-related metabolic interactions that may account for variability in drug scheduling and selection. Whereas we recognize influences may occur, we do not assume hormones alone can yield clinically significant metabolic changes. Rather, we believe that hormonal influences should be considered along with other elements that may affect drugs metabolism, such as concomitant medications, age-related pharmacokinetic changes, and genetic polymorphisms, in order to deliver treatment personalization and ensure better tolerability and safety of anticancer treatments.

Tumor-Infiltrating Lymphocytes and Immune Response in HER2-Positive Breast Cancer

Human epidermal growth factor receptor 2-positive (HER2-positive) breast cancer accounts for 15 to 25% of breast cancer cases. Although therapies based on the use of monoclonal anti-HER2 antibodies present clinical benefit for a subtype of patients with HER2-positive breast cancer, more than 50% of them are unresponsive to targeted therapies or they eventually relapse. In recent years, reactivation of the adaptive immune system in patients with solid tumors has emerged as a therapeutic option with great potential for clinical benefit. Since the approval of the first treatment directed against HER2 as a therapeutic target, the range of clinical options has expanded greatly, and, in this sense, cellular immunotherapy with T cells relies on the cytotoxicity generated by these cells, which ultimately leads to antitumor activity. Lymphocytic infiltration of tumors encompasses a heterogeneous population of immune cells within the tumor microenvironment that exhibits distinct patterns of immune activation and exhaustion. The prevalence and prognostic value of tumor-infiltrating lymphocyte (TIL) counts are associated with a favorable prognosis in HER2-positive breast cancers. This review discusses emerging findings that contribute to a better understanding of the role of immune infiltrates in HER2-positive breast cancer. In addition, it summarizes the most recent results in HER2-positive breast cancer immunotherapy and anticipates which therapeutic strategies could be applied in the immediate future.

Antibody drug conjugates targeting HER2: Clinical development in metastatic breast cancer

The identification of the HER2 alteration as an actionable oncogenic driver in breast cancer has propelled the development of HER-targeting monoclonal antibodies (mAb) such as trastuzumab and pertuzumab, which led to dramatic improvements in survival outcomes. Lately, the great strides made toward developing antibody-conjugation methods have led to the development of a new class of compelling compounds, the antibody-drug conjugates (ADCs) targeting HER2 which have profoundly transformed the treatment landscape of breast cancer. HER2-targeting ADCs, trastuzumab-emtansine and trastuzumab-deruxtecan, have improved the overall survival in the second and third-line settings with manageable adverse events. Other HER2-targeting ADCs using novel technological advances in the antibody, linker and/or payload conception have shown promising activity in preclinical and clinical studies and some of them are now being evaluated in larger clinical trials. Multiple challenges still impede the success of ADCs in breast cancer namely the lack of a comprehensive understanding of resistance mechanisms as well as the mechanisms of action of ADCs in special subgroups of patients such as those with low or ultra-low HER2 expression and patients with brain or leptomeningeal metastases (BM). In this framework, we review the approved indications and ongoing trials for HER2-targeting ADCs, across patient subgroups, including those with BM and discuss the associated potential mechanisms of action and resistance. Last, we provide an overview of the future perspectives involving HER2-targeting ADCs in breast cancer.

Phase Ib study of pembrolizumab in combination with trastuzumab emtansine for metastatic HER2-positive breast cancer

Background

Preclinical and clinical data support potential synergy between anti-HER2 therapy plus immune checkpoint blockade. The safety and tolerability of trastuzumab emtansine (T-DM1) combined with pembrolizumab is unknown.

Methods

This was a single-arm phase Ib trial (registration date January 26, 2017) of T-DM1 plus pembrolizumab in metastatic, human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Eligible patients had HER2-positive, metastatic breast cancer previously treated with taxane, trastuzumab, and pertuzumab, and were T-DM1-naïve. A dose de-escalation design was used, with a dose-finding cohort followed by an expansion cohort at the recommended phase 2 dose (RP2D), with mandatory baseline biopsies. The primary endpoint was safety and tolerability. Secondary endpoints included objective response rate (ORR) and progression-free survival (PFS). Immune biomarkers were assessed using histology, protein/RNA expression, and whole exome sequencing. Associations between immune biomarkers and treatment response, and biomarker changes before and during treatment, were explored.

Results

20 patients received protocol therapy. There were no dose-limiting toxicities. The RP2D was 3.6 mg/kg T-DM1 every 21 days plus 200 mg pembrolizumab every 21 days. 85% of patients experienced treatment-related adverse events (AEs) ≥grade 2, 20% of patients experienced grade 3 AEs, and no patients experienced grade >4 AEs. Four patients (20%) experienced pneumonitis (three grade 2 events; one grade 3 event). ORR was 20% (95% CI 5.7% to 43.7%), and median PFS was 9.6 months (95% CI 2.8 to 16.0 months). Programmed cell death ligand-1 and tumor infiltrating lymphocytes did not correlate with response in this small cohort.

Conclusions

T-DM1 plus pembrolizumab was a safe and tolerable regimen. Ongoing trials will define if there is a role for checkpoint inhibition in the management of HER2-positive metastatic breast cancer.

Trial registration number

NCT03032107.

Combining Radiotherapy and Immunotherapy in Metastatic Breast Cancer: Current Status and Future Directions

The role of radiotherapy and immunotherapy with immune checkpoint inhibitors (ICI) is of emerging interest in many solid tumours, including breast cancer. There is increasing evidence that the host’s immune system plays an important role in influencing the response to treatment and prognosis in breast cancer. Several pre-clinical studies and clinical trials have reported on the ‘abscopal effect—regression of distant untreated tumour sites, mediated by an immunological response following ionizing radiation to a targeted tumour site. Stereotactic Ablative Body Radiotherapy (SABR) is a non-invasive technique used to augment various immune responses with an ablative tumoricidal dose when compared to conventional radiotherapy. SABR is characterized by typically 1–5 precision radiotherapy treatments that simultaneously deliver a high dose, whilst sparing normal tissues. Following SABR, there is evidence of systemic immune activation in patients with increased PD1 expression on CD8+ and CD4+ T cells. Studies continue to focus on metastatic triple-negative disease, a highly immunogenic subtype of breast cancer with poor prognosis. In this review, we discuss the immunological effect of SABR, alone and in combination with immunotherapy, and the importance of dose and fractionation. We also propose future strategies for treating oligometastatic disease, where this approach may be most useful for producing durable responses.

Programmed Death-Ligand 1 (PD-L1) as Immunotherapy Biomarker in Breast Cancer

Breast cancer constitutes the most common malignant neoplasm in women around the world. Approximately 12% of patients are diagnosed with metastatic stage, and between 5 and 30% of early or locally advanced BC patients will relapse, making it an incurable disease. PD-L1 ligation is an immune inhibitory molecule of the activation of T cells, playing a relevant role in numerous types of malignant tumors, including BC. The objective of the present review is to analyze the role of PD-L1 as a biomarker in the different BC subtypes, adding clinical trials with immune checkpoint inhibitors and their applicable results. Diverse trials using immunotherapy with anti-PD-1/PD-L1 in BC, as well as prospective or retrospective cohort studies about PD-L1 in BC, were included. Despite divergent results in the reviewed studies, PD-L1 seems to be correlated with worse prognosis in the hormone receptor positive subtype. Immune checkpoints inhibitors targeting the PD-1/PD-L1 axis have achieved great response rates in TNBC patients, especially in combination with chemotherapy, making immunotherapy a new treatment option in this scenario. However, the utility of PD-L1 as a predictive biomarker in the rest of BC subtypes remains unclear. In addition, predictive differences have been found in response to immunotherapy depending on the stage of the tumor disease. Therefore, a better understanding of tumor microenvironment, as well as identifying new potential biomarkers or combined index scores, is necessary in order to make a better selection of the subgroups of BC patients who will derive benefit from immune checkpoint inhibitors.

Multiple Antitumor Molecular Mechanisms Are Activated by a Fully Synthetic and Stabilized Pharmaceutical Product Delivering the Active Compound Sulforaphane (SFX-01) in Preclinical Model of Human Glioblastoma

Frequent relapses and therapeutic resistance make the management of glioblastoma (GBM, grade IV glioma), extremely difficult. Therefore, it is necessary to develop new pharmacological compounds to be used as a single treatment or in combination with current therapies in order to improve their effectiveness and reduce cytotoxicity for non-tumor cells. SFX-01 is a fully synthetic and stabilized pharmaceutical product containing the α-cyclodextrin that delivers the active compound 1-isothiocyanato-4-methyl-sulfinylbutane (SFN) and maintains biological activities of SFN. In this study, we verified whether SFX-01 was active in GBM preclinical models. Our data demonstrate that SFX-01 reduced cell proliferation and increased cell death in GBM cell lines and patient-derived glioma initiating cells (GICs) with a stem cell phenotype. The antiproliferative effects of SFX-01 were associated with a reduction in the stemness of GICs and reversion of neural-to-mesenchymal trans-differentiation (PMT) closely related to epithelial-to-mesenchymal trans-differentiation (EMT) of epithelial tumors. Commonly, PMT reversion decreases the invasive capacity of tumor cells and increases the sensitivity to pharmacological and instrumental therapies. SFX-01 induced caspase-dependent apoptosis, through both mitochondrion-mediated intrinsic and death-receptor-associated extrinsic pathways. Here, we demonstrate the involvement of reactive oxygen species (ROS) through mediating the reduction in the activity of essential molecular pathways, such as PI3K/Akt/mTOR, ERK, and STAT-3. SFX-01 also reduced the in vivo tumor growth of subcutaneous xenografts and increased the disease-free survival (DFS) and overall survival (OS), when tested in orthotopic intracranial GBM models. These effects were associated with reduced expression of HIF1α which, in turn, down-regulates neo-angiogenesis. So, SFX-01 may have potent anti-glioma effects, regulating important aspects of the biology of this neoplasia, such as hypoxia, stemness, and EMT reversion, which are commonly activated in this neoplasia and are responsible for therapeutic resistance and glioma recurrence. SFX-01 deserves to be considered as an emerging anticancer agent for the treatment of GBM. The possible radio- and chemo sensitization potential of SFX-01 should also be evaluated in further preclinical and clinical studies.

A review of immune checkpoint blockade in breast cancer

In the recent years characterized by the cancer immunotherapy revolution, attention has turned to how to potentially boost and/or generate an efficient anti-tumor immune response in breast cancer (BC). Clinical activity of immune checkpoint blockade (ICB) targeting PD-1 or PD-L1 in BC has been more evident in the triple negative subtype and in earlier lines of the treatment. Remarkably, some responders to single agent ICB have achieved durable responses with metastatic disease, possibly as a result of treatment-induced immunological memory. However, most BC are immunologically quiescent and current research efforts developing ICB combinations are attempting to convert "cold" into "hot" tumors by manipulating the tumor microenvironment, expanding anti-tumor T cells improving efficient antigen presentation, and suppressing pro-tumor inhibitory cells. The aim of this review is to summarize existing data on the efficacy of immune checkpoint blockers as single agents and combination strategies in all BC subtypes, highlighting the BC subgroups that benefit most from ICB.

Immune Markers and Tumor-Related Processes Predict Neoadjuvant Therapy Response in the WSG-ADAPT HER2-Positive/Hormone Receptor-Positive Trial in Early Breast Cancer

Prognostic or predictive biomarkers in HER2-positive early breast cancer (EBC) may inform treatment optimization. The ADAPT HER2-positive/hormone receptor-positive phase II trial (NCT01779206) demonstrated pathological complete response (pCR) rates of ~40% following de-escalated treatment with 12 weeks neoadjuvant ado-trastuzumab emtansine (T-DM1) ± endocrine therapy. In this exploratory analysis, we evaluated potential early predictors of response to neoadjuvant therapy. The effects of PIK3CA mutations and immune (CD8 and PD-L1) and apoptotic markers (BCL2 and MCL1) on pCR rates were assessed, along with intrinsic BC subtypes. Immune response and pCR were lower in PIK3CA-mutated tumors compared with wildtype. Increased BCL2 at baseline in all patients and at Cycle 2 in the T-DM1 arms was associated with lower pCR. In the T-DM1 arms only, the HER2-enriched subtype was associated with increased pCR rate (54% vs. 28%). These findings support further prospective pCR-driven de-escalation studies in patients with HER2-positive EBC.

Targeting HER2 in Breast Cancer: Latest Developments on Treatment Sequencing and the Introduction of Biosimilars

Approximately 20% of all breast cancers overexpress the human epidermal growth factor receptor 2 (HER2). Targeting breast cancer through this vital oncogenic protein has been a major step towards improved patient outcomes. Today, several anti-HER2 agents are in clinical use including: the monoclonal antibodies trastuzumab and pertuzumab; the small molecule inhibitors lapatinib, neratinib, and tucatinib; and the antibody-drug conjugates ado-trastuzumab emtansine and trastuzumab deruxtecan, in some jurisdictions. In addition, several trastuzumab biosimilars have recently been granted regulatory approval in North America and the EU, and are enhancing patient access to HER2-directed therapy. The various agents differ greatly in their side-effect profiles and approved indications, from neoadjuvant and adjuvant use in early disease, to first- and later-line use in metastatic disease. This review discusses the current treatment recommendations for the use of anti-HER2 agents alone and in combination, examines the latest advances in HER2-targeted drugs and how they may be best applied in clinical practice, and provides guidance on optimal sequencing of the growing array of therapeutic options for HER2-positive breast cancer.

First-Line Treatment with a Cyclin-Dependent Kinase 4/6 Inhibitor Plus an Aromatase Inhibitor for Metastatic Breast Cancer in Alberta

In this analysis, we describe population-based outcomes for first-line treatment with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) combined with an aromatase inhibitor (AI). All patients who were prescribed CDK4/6i + AI from January 2016 through June 2019 were included. Patient demographics, tumour and treatment characteristics were collected and described. Survival distributions were estimated using the Kaplan–Meier method. Multivariate analysis (MVA) was constructed to examine associations between potentially prognostic clinical variables and progression-free survival (PFS). In total, 316 patients were included. The median age was 61 years. After a median follow-up of 28.1 months, the median PFS was 37.9 months (95% CI, 26.7–NR). In the MVA, PR-negative tumour (HR, 2.37; 95% CI, 1.45–3.88; p = 0.001) and CDK4/6i dose reduction (HR, 1.51; 95% CI, 1.06–2.16; p = 0.022) predicted worse PFS. Median overall survival (OS) was not reached. The 30-month and 36-month OS rates were 74% and 68%, respectively. Of patients who progressed, 89% received second-line treatment. Median time to progression on second-line chemotherapy was 9.0 (5.8–17.6) months, and median time to progression on second-line hormonal therapy +/− targeted agent was 4.0 (3.4–8.6) months (p = 0.012). CDK4/6i + AI as first-line treatment for HR-positive, HER2-negative MBC in Alberta is justified based on favourable PFS and early OS outcomes.

Ribociclib-Induced Pneumonitis: A Case Report

BACKGROUND

Cyclin-dependent kinase 4/6 (CDK 4/6) inhibitors have been a significant breakthrough in the management of hormone receptor-positive, HER2-negative metastatic breast cancer based on the results of several large phase III randomized trials. The most common reported toxicity is myelosuppression due to disease such as leukopenia, neutropenia, and thrombocytopenia. Other toxicities associated with CDK 4/6 inhibitors include mucositis, fatigue, gastrointestinal side effects, hepatic toxicities, and QTc prolongation. Despite a good toxicity profile in pivotal studies, the increased rates of use in clinical practice may show less prevalent but lethal toxicity such as lung injury.

CASE PRESENTATION

Here, we describe a female patient with metastatic hormone receptor-positive/human epidermal growth factor 2-negative breast cancer who developed lung toxicity while on ribociclib.

DISCUSSION

Lung injury is a possible side effect of CDK 4/6 inhibitors and there is an increasing need to understand the management of this side effect.

Impact of Anti-HER2 Treatments Combined With Atezolizumab on the Tumor Immune Microenvironment in Early or Metastatic Breast Cancer: Results From a Phase Ib Study

BACKGROUND

Despite advances, there continues to be unmet need in breast cancer. Combining anti-programmed death-ligand 1 (PD-L1) cancer immunotherapy atezolizumab with other targeted therapies may enhance T-cell-dependent cytolytic antitumor activity.

METHODS

This open-label, phase Ib study evaluated the safety of atezolizumab-based combinations with antibody-dependent cellular cytotoxicity or antibody-drug conjugate (ADC) agents. Patients with unresectable human epidermal growth factor receptor 2-positive (HER2⁺) locally advanced or metastatic breast cancer (mBC) received atezolizumab with trastuzumab/pertuzumab, atezolizumab with the ADC ado-trastuzumab emtansine (T-DM1), or atezolizumab with trastuzumab/pertuzumab and docetaxel. In an early-breast cancer (eBC) "window of opportunity" study, patients with operable HER2⁺ locally advanced or inflammatory eBC received neoadjuvant atezolizumab with trastuzumab/pertuzumab or atezolizumab/T-DM1, followed by docetaxel, carboplatin, and trastuzumab/pertuzumab. Exploratory outcomes included tumor response and biomarkers.

RESULTS

By March 15, 2019, 73 patients were enrolled. Safety findings were consistent with the treatment components' individual profiles. Objective responses were observed in 2 of 6 and 5 of 14 patients in 2 mBC cohorts receiving atezolizumab/T-DM1 and in 6 of 6 patients with mBC receiving atezolizumab, trastuzumab/pertuzumab, and docetaxel. PD-L1 in immune cells was the only biomarker that increased with atezolizumab/T-DM1. In the window of opportunity cohorts, PD-L1 levels and CD8⁺ T-cell infiltration increased from baseline in HER2⁺ eBC tumors receiving atezolizumab with trastuzumab/pertuzumab or T-DM1, irrespective of response. Despite increases in T-cell and B-cell gene signatures with trastuzumab/pertuzumab, but not T-DM1, neither combination promoted T-cell receptor clonal expansion.

CONCLUSION

Atezolizumab with antibody-dependent cellular cytotoxicity or ADC agents appears safe and may activate the adaptive immune system of patients with HER2⁺ eBC tumors more than those with mBC tumors.

Efficacy and Safety of Pyrotinib Versus T-DM1 in HER2+ Metastatic Breast Cancer Patients Pre-Treated With Trastuzumab and a Taxane: A Bayesian Network Meta-Analysis

Purpose

To compare the efficacy and safety between pyrotinib (Pyr) and trastuzumab emtansine (T-DM1) in pre-treated human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC) patients.

Methods

A comprehensive literature search of the PubMed, EMBASE, and Web of Science was performed in August 2020. Randomized clinical trials comparing the efficacy and safety between different anti-HER2 regimens in patients pre-treated with trastuzumab (Tra) and a taxane in metastatic settings (≤second-line treatment) were included. A fixed effects network meta-analysis based on the Bayesian inferential framework was conducted for progression-free survival (PFS), overall survival (OS), overall response rate (ORR), and grade ≥3 adverse events (AEs). Values of surface under cumulative ranking probability curve (SUCRA) were calculated to offer a ranking of all regimens.

Results

Twelve studies with 4,353 subjects were identified. Nine regimens were included into the network: T-DM1, lapatinib-capecitabine (Lap-Cap), Tra-Cap, Cap, neratinib (Ner), pertuzumab (Per)-Tra-Cap, Pyr-Cap, atezolizumab (Ate)-T-DM1, and Ner-Cap. For PFS, Pyr-Cap was more favorable than T-DM1 (hazard ratio, 95% confidence interval: 0.77, 0.70–0.86), Lap-Cap (0.64, 0.59–0.69), Tra-Cap (0.63, 0.56–0.70), Cap (0.50, 0.45–0.56), Ner (0.59, 0.51–0.69), Per-Tra-Cap (0.68, 0.59–0.79), and Ner-Cap (0.72, 0.64–0.81). For OS, Pyr-Cap showed further improvement than Lap-Cap (hazard ratio, 95% confidence interval: 0.71, 0.52–0.99), Cap (0.68, 0.49–0.96), and Ner (0.65, 0.45–0.94). For ORR, Pyr-Cap was significantly superior than Cap (odds ratio, 95% confidence interval: 7.87, 1.22–56.51). No significant difference was observed in grade ≥3 AEs among all the regimens. Pyr-Cap ranked in the highest in PFS, OS, ORR, and grade ≥3 AEs (SUCRA = 99.4, 89.7, 86.4, and 89.3%).

Conclusions

These results indicate that Pyr may be more effective than T-DM1 in HER2+ MBC patients pre-treated with Tra and a taxane. However, it may be associated with more grade ≥3 AEs.

Nanodelivery of natural isothiocyanates as a cancer therapeutic

Natural isothiocyanates (ITCs) are phytochemicals abundant in cruciferous vegetables with the general structure, R-NCS. They are bioactive organosulfur compounds derived from the hydrolysis of glucosinolates by myrosinase. A significant number of isothiocyanates have been isolated from different plant sources that include broccoli, Brussels sprouts, cabbage, cauliflower, kale, mustard, wasabi, and watercress. Several ITCs have been demonstrated to possess significant pharmacological properties including: antioxidant, anti-inflammatory, anti-cancer and antimicrobial activities. Due to their chemopreventive effects on many types of cancer, ITCs have been regarded as a promising anti-cancer therapeutic agent without major toxicity concerns. However, their clinical application has been hindered by several factors including their low aqueous solubility, low bioavailability, instability as well as their hormetic effect. Moreover, the typical dietary uptake of ITCs consumed for promotion of good health may be far from their bioactive (or cytotoxic) dose necessary for cancer prevention and/or treatment. Nanotechnology is one of best options to attain enhanced efficacy and minimize hormetic effect for ITCs. Nanoformulation of ITCs leads to enhance stability of ITCs in plasma and emphasize on their chemopreventive effects. This review provides a summary of the potential bioactivities of ITCs, their mechanisms of action for the prevention and treatment of cancer, as well as the recent research progress in their nanodelivery strategies to enhance solubility, bioavailability, and anti-cancer efficacy.

Immunotherapy for the Breast Cancer treatment: Current Evidence and Therapeutic Options

Breast cancer (BC) stands at the first position among all forms of malignancies found in women globally. The available therapeutic approaches for breast cancer includes chemotherapy, radiation therapy, hormonal therapy and finally surgery. Despite the conventional therapies, in recent years the advance immunology based therapeutics emerge a potential in breast cancer treatment, including immune checkpoint blockades, vaccines and in combination with other treatment strategies. Although, commonly used treatments like trastuzumab/pertuzumab for human epidermal growth factor receptor 2 (Her2) positive and hormone therapy for estrogen receptor (ER) positive and/or progesterone receptor (PR) positive BC are specific but triple negative breast cancer (TNBC) cases remain a great challenge for treatment measures. Immune checkpoint inhibitors (anti-PD-1/ anti-CTLA-4) and anti-cancer vaccines (NeuVax, Muc-1, AVX901, INO-1400 and CEA), either alone or in combination with other therapies have created new paradigm in therapeutic world. In this review, we highlighted the current immunotherapeutic aspects and their ongoing trials towards the better treatment regimen for BC.

Novel combinatorial strategies for boosting the efficacy of immune checkpoint inhibitors in advanced breast cancers

The year 2019 witnessed the first approval of an immune checkpoint inhibitor (ICI) for the management of triple negative breast cancers (TNBC) that are metastatic and programmed death ligand (PD)-L1 positive. Extensive research has focused on testing ICI-based combinatorial strategies, with the ultimate goal of enhancing the response of breast tumors to immunotherapy to increase the number of breast cancer patients benefiting from this transformative treatment. The promising investigational strategies included immunotherapy combinations with monoclonal antibodies (mAbs) against human epidermal growth factor receptor (HER)-2 for the HER2 + tumors versus cyclin-dependent kinase (CDK)4/6 inhibitors in the estrogen receptor (ER) + disease. Multiple approaches are showing signals of success in advanced TNBC include employing Poly (ADP-ribose) polymerase (PARP) inhibitors, tyrosine kinase inhibitors, MEK inhibitors, phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (AKT) signaling inhibitors or inhibitors of adenosine receptor, in combination with the classical PD-1/PD-L1 immune checkpoint inhibitors. Co-treatment with chemotherapy, high intensity focused ultrasound (HIFU) or interleukin-2-βɣ agonist have also produced promising outcomes. This review highlights the latest combinatorial strategies under development for overcoming cancer immune evasion and enhancing the percentage of immunotherapy responders in the different subsets of advanced breast cancers.

Immune Checkpoint Blockade in HER2-Positive Breast Cancer: What Role in Early Disease Setting?

Simple Summary

This work aims to discuss how an anti- or pro-tumor immune response could be manipulated through immune checkpoint blockade in patients with early stage HER2-positive breast cancer. By summarizing previously published evidence in the field, authors present their personal view on how immune checkpoint blockade could be implemented in the neoadjuvant setting in this patient population. The hypothesis being presented is that an appropriate and effective administration of immune checkpoint blockade could assure a lasting control of the disease, by preventing relapses. One of the research priorities should be the identification of the patients who could benefit more by this strategy.

Abstract

The present commentary synthesizes the current evidence on the role of the immune response in HER2-positive breast cancer. It points out the strengths and weaknesses of the findings observed so far, particularly in the early setting, including the clinical significance of scoring tumor-infiltrating lymphocytes. A figure proposing research hypotheses for the implementation of immune checkpoint blockade use for patient candidates to neoadjuvant treatment is presented.

Prevalence Study of PD-L1 SP142 Assay in Metastatic Triple-negative Breast Cancer

Metastatic triple-negative breast cancer (mTNBC) is the most aggressive breast cancer subtype. Programmed death ligand 1 (PD-L1) on immune cells (IC) using the VENTANA SP142 assay is linked to improved clinical outcome in atezolizumab plus nab-paclitaxel-treated patients with mTNBC in the IMpassion130 study. The goal of the current study was to evaluate prevalence of VENTANA SP142 PD-L1 assay by anatomic location in 670 histologically confirmed TNBC cases from subjects with metastatic disease screened for the phase 1 study PCD4989g (NCT01375842). PD-L1 immunohistochemistry was centrally tested on tumor cells (TC) and on tumor infiltrating IC, following manufacturer's instructions. At a 1% cutoff, tumor PD-L1 was more prevalent in IC than TC: 46% were PD-L1 IC+/TC-, 3% were PD-L1 IC-/TC+, and 10% were PD-L1 IC+/TC+. PD-L1 IC and TC immunostaining correlated with CD274 RNA expression, as assessed by fluidigm. Analyses of anatomic locations suggest that prevalence of PD-L1 IC+ was highest in lymph nodes (65.0%), lowest in liver metastases (26.9%), while breast tissue was intermediate (57.1%). Matched paired samples from the same subject collected synchronously or asynchronously showed a PD-L1 IC status agreement of 80% (8/10) and 75% (15/20), respectively. Our results suggest that the anatomic location of metastases and time of collection may influence the detection of PD-L1.

Current status of PD-1/PD-L1 blockade immunotherapy in breast cancer

Over the past 10 years, immunotherapy with immune checkpoint inhibitors has revolutionized the management of various cancers. However, immunotherapy in breast cancer has not been successful. Breast cancer has long been recognized as an immunologically 'cold' tumor, although a higher frequency of tumor-infiltrating lymphocytes present in certain subtypes and an association between tumor-infiltrating lymphocytes and favorable prognosis have been reported. In March 2019, the combination of atezolizumab and nanoparticle albumin-bound paclitaxel was granted accelerated approval in the United States for the treatment of programmed death-ligand 1-positive advanced or metastatic triple-negative breast cancer. This finally opened the door for immune checkpoint blockade therapy for breast cancer. Several clinical trials have been conducted using different combinations of immune checkpoint inhibitors and chemotherapy or targeted agents in various treatment settings for metastatic breast cancer and early-stage breast cancer. In this review, we summarize recent advances in immune checkpoint blockade therapy and predictive biomarkers in breast cancer.

Immunotherapy as a partner for HER2-directed therapies

Introduction: Existing HER2-targeted therapies modulate the tumor microenvironment and the immunologic response cancer in a favorable way. While these therapies have made dramatic improvements in the treatment and prognosis of HER2-overexpressing malignancies, additional treatment options are still needed.Areas covered: This review covers the immunomodulatory effects of approved HER2-targeted therapies. We discuss the preclinical data that demonstrate an additive effect of the combination of trastuzumab or other HER2-targeting agents with immunomodulatory drugs. Finally, we report the initial studies on the combination of HER2-targeted agents together with immune checkpoint inhibitors or cancer vaccines in breast cancer.Expert opinion: Preclinical data suggest a synergistic effect of HER2-targeted therapy together with both checkpoint inhibitor and cancer vaccine immunotherapy. Results from initial trials with PD-1/PD-L1-blocking therapy together with HER2-targeted therapy have been negative, but responses were seen in patients with PD-L1+ breast cancer. Trastuzumab together with HER2-targeted cancer vaccination has shown benefits in triple negative breast cancer. Further trials are necessary and warranted to confirm the benefit of these combinations.

Improving the Odds in Advanced Breast Cancer With Combination Immunotherapy: Stepwise Addition of Vaccine, Immune Checkpoint Inhibitor, Chemotherapy, and HDAC Inhibitor in Advanced Stage Breast Cancer

Breast tumors commonly harbor low mutational burden, low PD-L1 expression, defective antigen processing/presentation, and an immunosuppressive tumor microenvironment (TME). In a malignancy mostly refractory to checkpoint blockade, there is an unmet clinical need for novel combination approaches that increase tumor immune infiltration and tumor control. Preclinical data have guided the development of this clinical trial combining 1) BN-Brachyury (a poxvirus vaccine platform encoding the tumor associated antigen brachyury), 2) bintrafusp alfa (a bifunctional protein composed of the extracellular domain of the TGF-βRII receptor (TGFβ "trap") fused to a human IgG1 anti-PD-L1), 3), entinostat (a class I histone deacetylase inhibitor), and 4) T-DM1 (ado-trastuzumab emtansine, a standard of care antibody-drug conjugate targeting HER2). We hypothesize that this tetratherapy will induce a robust immune response against HER2+ breast cancer with improved response rates through 1) expanding tumor antigen-specific effector T cells, natural killer cells, and immunostimulatory dendritic cells, 2) improving antigen presentation, and 3) decreasing inhibitory cytokines, regulatory T cells, and myeloid-derived suppressor cells. In an orthotopic HER2+ murine breast cancer model, tetratherapy induced high levels of antigen-specific T cell responses, tumor CD8+ T cell/Treg ratio, and augmented the presence of IFNγ- or TNFα-producing CD8+ T cells and IFNγ/TNFα bifunctional CD8+ T cells with increased cytokine production. Similar effects were observed in tumor CD4+ effector T cells. Based on this data, a phase 1b clinical trial evaluating the stepwise addition of BN-Brachyury, bintrafusp alfa, T-DM1 and entinostat in advanced breast cancer was designed. Arm 1 (TNBC) receives BN-Brachyury + bintrafusp alfa. Arm 2 (HER2+) receives T-DM1 + BN-Brachyury + bintrafusp alfa. After safety is established in Arm 2, Arm 3 (HER2+) will receive T-DM1 + BN-Brachyury + bintrafusp alfa + entinostat. Reimaging will occur every 2 cycles (1 cycle = 21 days). Arms 2 and 3 undergo research biopsies at baseline and after 2 cycles to evaluate changes within the TME. Peripheral immune responses will be evaluated. Co-primary objectives are response rate and safety. All arms employ a safety assessment in the initial six patients and a 2-stage Simon design for clinical efficacy (Arm 1 if ≥ three responses of eight then expand to 13 patients; Arms 2 and 3 if ≥ four responses of 14 then expand to 19 patients per arm). Secondary objectives include progression-free survival and changes in tumor infiltrating lymphocytes. Exploratory analyses include changes in peripheral immune cells and cytokines. To our knowledge, the combination of a vaccine, an anti-PD-L1 antibody, entinostat, and T-DM1 has not been previously evaluated in the preclinical or clinical setting. This trial (NCT04296942) is open at the National Cancer Institute (Bethesda, MD).

Immune Infiltrates in Breast Cancer: Recent Updates and Clinical Implications

In recent decades, the increasing interest in the field of immunotherapy has fostered an intense investigation of the breast cancer (BC) immune microenvironment. In this context, tumor-infiltrating lymphocytes (TILs) have emerged as a clinically relevant and highly reproducible biomarker capable of affecting BC prognosis and response to treatment. Indeed, the evaluation of TILs on primary tumors proved to be strongly prognostic in triple-negative (TN) BC patients treated with either adjuvant or neoadjuvant chemotherapy, as well as in early TNBC patients not receiving any systemic treatment, thus gaining level-1b evidence in this setting. In addition, a strong relationship between TILs and pathologic complete response after neoadjuvant chemotherapy has been reported in all BC subtypes and the prognostic role of higher TILs in early HER2-positive breast cancer patients has also been demonstrated. The interest in BC immune infiltrates has been further fueled by the introduction of the first immune checkpoint inhibitors in the treatment armamentarium of advanced TNBC in patients with PD-L1-positive status by FDA-approved assays. However, despite these advances, a biomarker capable of reliably and exhaustively predicting immunotherapy benefit in BC is still lacking, highlighting the imperative need to further deepen this issue. Finally, more comprehensive evaluation of immune infiltrates integrating both the quantity and quality of tumor-infiltrating immune cells and incorporation of TILs in composite scores encompassing other clinically or biologically relevant biomarkers, as well as the adoption of software-based and/or machine learning platforms for a more comprehensive characterization of BC immune infiltrates, are emerging as promising strategies potentially capable of optimizing patient selection and stratification in the research field. In the present review, we summarize available evidence and recent updates on immune infiltrates in BC, focusing on current clinical applications, potential clinical implications and major unresolved issues.

An overview of immune checkpoint inhibitors in breast cancer

Although breast cancer is not traditionally considered an immunogenic type of tumor, the combination of immunotherapy and chemotherapy has recently emerged as a novel treatment option in triple-negative subtype in the advanced setting and other similar combinations of immune checkpoint inhibitors with chemotherapy are expected to become part of the neoadjuvant management in the near future. In addition, encouraging results have been observed with the combination of immune checkpoint blockade with diverse biological agents, including anti-HER2 agents, CDK 4/6 inhibitors, PARP-inhibitors. The present review summarized the available evidence coming from clinical trials on the role of immune checkpoint inhibitors in the management of breast cancer, both in advanced and early setting.

Margetuximab for the treatment of HER2-positive metastatic breast cancer

INTRODUCTION

No specific standard treatment is currently recommended for HER2-positive advanced breast cancer (BC) patients progressing to dual HER2 blockade and to trastuzumab emtansine (TDM-1). However, several novel anti-HER2 agents are emerging and rapidly revolutionizing this setting. Among these, the FC-engineered monoclonal antibody margetuximab has recently demonstrated to slightly improve progression-free survival (PFS) compared with trastuzumab, when combined with chemotherapy for pretreated HER2-positive advanced BC.

AREAS COVERED

The present review article recapitulates the clinical development of margetuximab, critically discussing its implications in the current landscape of BC treatment algorithms.

EXPERT OPINION

The clinical role of Margetuximab can only be interpreted in view of the rapidly evolving treatment landscape for pretreated HER2-positive advanced BC. Indeed, the recently approved anti-HER2 agents tucatinib and trastuzumab deruxtecan currently represent appealing options for the post-TDM1 setting, while margetuximab may have a role after progression to the abovementioned agents, in case of a future approval. Regardless of its clinical uptake, it should be noted that the development of margetuximab has relevantly improved our biological understanding of HER2-positive BC, highlighting the implication of patient's genotype in determining treatment outcomes, as well as the relevance of antibody-dependent cellular cytotoxicity (ADCC) in the context of HER2-blockade.

Immunotherapy for early breast cancer: too soon, too superficial, or just right?

Immunotherapy emerged as a new treatment modality for breast cancer, and its use is approved in combination with chemotherapy for first-line therapy in metastatic triple-negative breast cancer overexpressing PD-L1. As immune checkpoint inhibitors alone have modest clinical activity in advanced breast cancer, there is a growing interest in combinatorial modalities, and particularly for their rapid development in the early disease setting. The plethora of ongoing immunotherapy trials in early breast cancer comes at a time when solid data in advanced disease are still imperfect. This review offers a perspective on the efforts to establish the efficacy and safety of immunotherapeutic agents in early breast cancer.

Third-line treatment of HER2-positive advanced breast cancer: From no standard to a Pandora's box

Human epidermal growth factor receptor 2 positive (HER2+) advanced breast cancer (ABC) accounts for about 15-20% of all ABC cases. Large randomized trials have determined the standard first- and second-line treatments for this subgroup of patients, namely dual blockade plus chemotherapy and TDM1. However, no standard treatment is specifically recommended after TDM1, and most of the subsequent therapeutic choices commonly rely on old trials not optimally reflecting the current patient population. The recent FDA-approval of three novel anti-HER2 compounds is revolutionizing the field. In particular, trastuzumab deruxtecan was approved after showing unprecedented activity in a phase 2 trial for highly pretreated HER2+ ABC patients; tucatinib and neratinib were approved based on the results of the randomized HER2CLIMB and NALA trial, respectively. With an increasing arsenal of treatment options, clinical decision-making will need to take into account a variety of aspects, including differences in clinical trial designs, outcomes and toxicity profile of each drug, patient's characteristics and preferences.

Treatment Landscape for Patients with HER2-Positive Metastatic Breast Cancer: A Review on Emerging Treatment Options

The prognosis of HER2-positive metastatic breast cancer (MBC) has radically changed in recent years and continues to improve due to the broad application of effective therapies like monoclonal antibodies and small molecules targeting HER2. Persistent dependency of tumor cells on the oncogene HER2, on one hand, as well as low expression levels in healthy tissue, on the other hand, make this protein an ideal target for anti-cancer therapy. New HER2 targeting strategies including targeted delivery of cytotoxic drugs via HER2 receptor have been developed. Recently, the US Food and Drug Administration (FDA) approved three new drugs for the treatment of HER2-positive MBC: the antibody–drug conjugate trastuzumab deruxtecan and the two tyrosine kinase inhibitors neratinib and tucatinib. Here, we summarize recent publications and developments of novel anti-HER2 therapies like monoclonal antibodies with improved properties compared to trastuzumab and bispecific antibodies, which bind two different HER-epitopes or bring T cells closer to tumor cells. Furthermore, novel antibody-drug conjugates and small molecules against HER2 are discussed. These developments coupled with new combination strategies (eg, with CDK4/6 inhibitors or immunotherapy) will change the treatment landscape for patients with HER2-positive MBC very soon and will hopefully further improve clinical outcomes.

The root cause of drug resistance in HER2-positive breast cancer and the therapeutic approaches to overcoming the resistance

HER2 is a well-known oncogenic receptor tyrosine kinase. HER2 gene amplification occurs in about 20% of breast cancer (BC), which leads to overexpression of HER2 protein, known as HER2-positive BC. Inhibitors of HER2 have significantly improved the prognosis of patients with this subset of BC. Since 1998, seven HER2 inhibitors have been developed to treat this disease. However, drug resistance is common and remains a major unresolved clinical problem. Patients typically show disease progression after some time on treatment. This review discusses the complexity and diversified nature of HER2 signaling, the mechanisms of actions and therapeutic activities of all HER2 inhibitors, the roles of HER2 and other signaling proteins in HER2-positive BC resistant to the inhibitors, the non-cell-autonomous mechanisms of drug resistance, and the heterogeneity of tumor HER2 expression. The review presents the concept that drug resistance in HER2-positive BC results primarily from the inability of HER2 inhibitors to deplete HER2. Emerging therapeutics that are promising for overcoming drug resistance are also discussed.

Evolving standards of care and new challenges in the management of HER2-positive breast cancer

The management of human epidermal growth factor receptor (HER2)-positive breast cancer (BC) has rapidly evolved over the last 20 years. Major advances have led to US Food and Drug Administration approval of 7 HER2-targeted therapies for the treatment of early-stage and/or advanced-stage disease. Although oncologic outcomes continue to improve, most patients with advanced HER2-positive BC ultimately die of their disease because of primary or acquired resistance to therapy, and patients with HER2-positive early BC who have residual invasive disease after preoperative systemic therapy are at a higher risk of distant recurrence and death. The concept of treatment de-escalation and escalation is increasingly important to optimally tailor therapy for patients with HER2-positive BC and is a major focus of the current review. Research efforts in this regard are discussed as well as updates regarding the evolving standard of care in the (neo)adjuvant and metastatic settings, including the use of novel combination therapies. The authors also briefly discuss ongoing challenges in the management of HER2-positive BC (eg, intrinsic vs acquired drug resistance, the identification of predictive biomarkers, the integration of imaging techniques to guide clinical practice), and the treatment of HER2-positive brain metastases. Research aimed at superseding these challenges will be imperative to ensure continued progress in the management of HER2-positive BC going forward.

Current advances in the diagnosis and personalized treatment of breast cancer: lessons from tumor biology

Breast cancer treatment has advanced enormously in the last decade. Most of this is due to advances reached in the knowledge regarding tumor biology, mainly in the field of diagnosis and treatment. This review brings information about how the genomics-based information contributed to advances in breast cancer diagnosis and prognosis perspective, as well as presents how tumor biology discoveries fostered the main therapeutic approaches available to treat such patients, based on a personalized point of view.

Biomarkers for HER2-positive metastatic breast cancer: Beyond hormone receptors

The overexpression of human epidermal growth factor receptor-2 (HER2) results in a biologically and clinically aggressive breast cancer (BC) subtype. Since the introduction of anti-HER2 targeted agents, survival rates of patients with HER2-positive metastatic BC have dramatically improved. Currently, although the treatment decision process in metastatic BC is primarily based on HER2 and hormone-receptor (HR) status, a rapidly growing body of data suggests that several other sources of biological heterogeneity may characterize HER2-positive metastatic BC. Moreover, pivotal clinical trials of new anti-HER2 antibody-drug conjugates showed encouraging results in HER2-low metastatic BC, thus leading to the possibility, in the near future, to expand the pool of patients suitable for HER2-targeted treatments. The present review summarizes and puts in perspective available evidence on biomarkers that hold the greatest promise to become potentially useful tools for optimizing HER2-positive metastatic BC patients' prognostic stratification and treatment in the next future. These biomarkers include HER2 levels and heterogeneity, HER3, intrinsic molecular subtypes by PAM50 analysis, DNA mutations, and immune-related factors. Molecular discordance between primary and metastatic tumors is also discussed.

Clinical Development of PD-1/PD-L1 Inhibitors in Breast Cancer: Still a Long Way to Go

OPINION STATEMENT

Currently, only patients with metastatic triple-negative breast cancer whose tumors are PD-L1 positive are eligible for receiving immunotherapy. Other studies have explored new combinations with PD-1/PD-L1 inhibitors in different disease settings and populations. Data from neoadjuvant trials testing the addition of PD-1/PD-L1 inhibitors to standard treatment are promising and have led to increases in pathologic complete response rates; however, data on survival outcomes are still immature. There is still much work needed to optimize benefits of immunotherapy in breast cancer and correlative studies in patients treated with immunotherapy are urgently needed to inform the best strategies for further development.

The path to a better biomarker: application of a risk management framework for the implementation of PD-L1 and TILs as immuno-oncology biomarkers in breast cancer clinical trials and daily practice

Immune checkpoint inhibitor therapies targeting PD-1/PD-L1 are now the standard of care in oncology across several hematologic and solid tumor types, including triple negative breast cancer (TNBC). Patients with metastatic or locally advanced TNBC with PD-L1 expression on immune cells occupying ≥1% of tumor area demonstrated survival benefit with the addition of atezolizumab to nab-paclitaxel. However, concerns regarding variability between immunohistochemical PD-L1 assay performance and inter-reader reproducibility have been raised. High tumor-infiltrating lymphocytes (TILs) have also been associated with response to PD-1/PD-L1 inhibitors in patients with breast cancer (BC). TILs can be easily assessed on hematoxylin and eosin-stained slides and have shown reliable inter-reader reproducibility. As an established prognostic factor in early stage TNBC, TILs are soon anticipated to be reported in daily practice in many pathology laboratories worldwide. Because TILs and PD-L1 are parts of an immunological spectrum in BC, we propose the systematic implementation of combined PD-L1 and TIL analyses as a more comprehensive immuno-oncological biomarker for patient selection for PD-1/PD-L1 inhibition-based therapy in patients with BC. Although practical and regulatory considerations differ by jurisdiction, the pathology community has the responsibility to patients to implement assays that lead to optimal patient selection. We propose herewith a risk-management framework that may help mitigate the risks of suboptimal patient selection for immuno-therapeutic approaches in clinical trials and daily practice based on combined TILs/PD-L1 assessment in BC. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Combination Strategies of Checkpoint Immunotherapy in Metastatic Breast Cancer

Checkpoint immunotherapy is emerging as a new therapeutic approach for metastatic breast cancer. Monotherapy of immunoagents against PD1/PD-L1 or CTLA-4 has shown little efficacy in these patients. Recently, to determine the optimal use of immunotherapy, there has been a rapid expansion in the number of clinical trials developing immunotherapy combinations. These combination therapeutic approaches can enhance various aspects of cancer immunity, such as tumor antigenicity or intratumor T cell infiltration, which provides a theoretical basis for combining them with checkpoint immunotherapy to achieve synergistic effects. Here, we review the available data and ongoing efforts to establish the safety and efficacy of immunoagents in combination with chemotherapy, radiotherapy, HER2-targeted therapy, CDK4/6 inhibitors, PARP inhibitors, and another checkpoint immunoagents.

Role of innate and adaptive immunity in the efficacy of anti-HER2 monoclonal antibodies for HER2-positive breast cancer

Anti-HER2 monoclonal antibodies (mAbs) such as trastuzumab are effective for all stages of HER2-positive breast cancer (BC). However, intrinsic or acquired resistance to these drugs may occur in a significant number of patients (pts) and, except for HER2 status, no validated predictive factors of response/resistance have been identified to date. This lack is in part due to the not yet fully elucidated mechanism of action of mAbs in vivo. Increasing evidence suggests a significant contribution of both innate and adaptive immunity to the antitumor effects of mAbs. The aim of this review was to describe the role of innate and adaptive immunity in the efficacy of anti-HER2 mAbs and to report known and novel strategies to be used for optimizing immune effects of anti-HER2 therapies for HER2-positive BC.

Clinico-Immunological Profile of a 67-Year-Old Woman Affected by HER2-Positive Breast Cancer and Autoimmune Dermatomyositis

A patient with HER2-positive early breast cancer (BC) developed dermatomyositis (DM), which disappeared after the first administration of adjuvant trastuzumab. No HER2 overexpression/amplification was observed in DM skin biopsies. Both BC and skin immune infiltrates were composed mostly of CD3+ T-lymphocytes. Interestingly, tumor-infiltrating lymphocytes expressed PD-1, which was negligible in skin-infiltrating lymphocytes, while both BC cells and keratinocytes were PD-L1-positive. High serum levels of endogenous anti-HER2 antibodies were detected, confirming the induction of a HER2-specific adaptive immune response. It may be argued that HER2-specific T-lymphocytes cross-reacted with one or more unknown skin antigens, causing DM. Trastuzumab may have silenced skin cross-reaction by eliminating any residual HER2-positive micrometastatic disease and, thus, inducing DM remission.