Strategies to overcome trastuzumab resistance in HER2-overexpressing breast cancers: focus on new data from clinical trials

HER2-targeted therapies for HER2-positive early-stage breast cancer: present and future

Breast cancer (BC) has the second highest incidence among cancers and is the leading cause of death among women worldwide. The human epidermal growth factor receptor 2 (HER2) is overexpressed in approximately 20%-30% of BC patients. The development of HER2-targeted drugs, including monoclonal antibodies (mAbs), tyrosine kinase inhibitors (TKIs) and antibody-drug conjugates (ADCs), has improved the operation rate and pathological remission rate and reduced the risk of postoperative recurrence for HER2-positive early-stage BC (HER2+ EBC) patients. This review systematically summarizes the mechanisms, resistance, therapeutic modalities and safety of HER2-targeted drugs and helps us further understand these drugs and their use in clinical practice for patients with HER2+ EBC.

UGT1A7 altered HER2-positive breast cancer response to trastuzumab by affecting epithelial-to-mesenchymal transition: A potential biomarker to identify patients resistant to trastuzumab treatment

HER2-positive (HER2+) breast cancer accounts for 20-30% of all breast cancers. Although trastuzumab has significantly improved the survival of patients with HER2+ breast cancer, more than 70% of patients develop drug resistance within one year of treatment. Differential-gene-expression analysis of trastuzumab-sensitive and resistant HER2+ breast cancer cell lines from GSE15043 was performed to identify the biomarkers associated with trastuzumab resistance. Differential biomarker expression was confirmed in FFPE tissues collected from clinical HER2+ breast cancer tumor samples that were sensitive or resistant to trastuzumab treatment. UGT1A7, a member of the uronic acid transferase family, was associated with trastuzumab resistance. UGT1A7 expression was downregulated in trastuzumab-resistant tumor tissues and in a cell line that developed trastuzumab resistance (BT474TR). Overexpressing UGT1A7 in BT474TR restored their sensitivity to trastuzumab treatment, whereas downregulating UGT1A7 expression in parental cells led to trastuzumab resistance. Importantly, UGT1A7 localized to the endoplasmic reticulum and altered stress responses. Furthermore, downregulating UGT1A7 expression promoted epithelial-to-mesenchymal transition (EMT) by affecting TWIST, SNAIL, and GRP78 expression and the AMP-activated protein kinase signaling pathway, thus contributing to trastuzumab resistance. This study demonstrated the important role and novel mechanisms of UGT1A7 in tumor responses to trastuzumab. Low UGT1A7 expression plays an important role in EMT and contributes to trastuzumab resistance. UGT1A7 has the potential to be developed as a biomarker for identifying patients who are resistant to trastuzumab treatment.

Antibody-drug conjugates combinations in cancer treatment

Antibody-drug conjugates (ADCs) have emerged as a promising class of anticancer agents. Currently, the Food and Drug Administration has granted approval to 12 compounds, with 2 later undergoing withdrawal. Moreover, several other compounds are currently under clinical development at different stages. Despite substantial antitumoral activity observed among different tumor types, adverse events and the development of resistance represent significant challenges in their use. Over the last years, an increasing number of clinical trials have been testing these drugs in different combinations with other anticancer agents, such as traditional chemotherapy, immune checkpoint inhibitors, monoclonal antibodies, and small targeted agents, reporting promising results based on possible synergistic effects and a potential for improved treatment outcomes among different tumor types. Here we will review combinations of ADCs with other antitumor agents aiming at describing the current state of the art and future directions.

Breast cancer immunotherapy: a comprehensive review

Cancer remains a major health problem despite numerous new medical interventions that have been introduced in recent years. One of the major choices for cancer therapy is so-called adoptive cell therapy (ACT). ACT can be performed using both innate immune cells, including dendritic cells (DCs), natural killer (NK) cells, and γδ T cells and acquired immune T cells. It has become possible to utilize these cells in both their native and modified states in clinical studies. Because of considerable success in cancer treatment, ACT now plays a role in advanced therapy protocols. Genetic engineering of autologous and allogeneic immune cells (T lymphocytes, NK cells, macrophages, etc.) with chimeric antigen receptors (CAR) is a powerful new tool to target specific antigens on cancer cells. The Food and Drug Administration (FDA) in the US has approved certain CAR-T cells for hematologic malignancies and it is hoped that their use can be extended to incorporate a variety of cells, in particular NK cells. However, the ACT method has some limitations, such as the risk of rejection in allogeneic engrafts. Accordingly, numerous efforts are being made to eliminate or minimize this and other complications. In the present review, we have developed a guide to breast cancer (BC) therapy from conventional therapy, through to cell-based approaches, in particular novel technologies including CAR with emphasis on NK cells as a new and safer candidate in this field as well as the more recent aptamer technology, which can play a major role in BC immunotherapy.

Randomized, open-label, phase II, biomarker study of immune-mediated mechanism of action of neoadjuvant subcutaneous trastuzumab in patients with locally advanced, inflammatory, or early HER2-positive breast cancer-Immun-HER trial (GOIRC-01-2016)

BACKGROUND

It is possible to induce immunomodulation in HER2-positive breast cancer (BC) by modifying the route of administration of trastuzumab.

METHODS

In this multicenter randomized phase II trial, all enrolled patients (pts) with T2-T4d HER2-positive BC received 3 cycles of neoadjuvant treatment (NAT) with fluorouracil, epirubicin and cyclophosphamide every 3 weeks (q21), followed by docetaxel/pertuzumab plus intravenous trastuzumab (arm A) or, docetaxel/pertuzumab plus subcutaneous (SC) trastuzumab (arm B) q21x4 cycles. After surgical operation, each pt was treated with trastuzumab q21x14 cycles using the same SC or intravenous formulation of NAT. Primary endpoint was the proportion of subjects with high stromal tumor-infiltrating lymphocytes (sTILs) in postneoadjuvant residual disease (RD).

RESULTS

Sixty-three pts (31 (arm A) and 32 (arm B)) were enrolled. Pathological complete response was obtained by 20/31 pts (64.5%; 95% CI 45.4% to 80.1%) in arm A and 19/32 pts (59.4%; 95% CI 40.1% to 76.3%) in arm B. High sTILs were observed in 27% and 46% of postneoadjuvant residual tumors in arms A and B, respectively. CD8+ T cells increased significantly in RDs of both arms (p=0.014 and 0.002 for arm A and B, respectively), whereas a significant decline in the level of CD4+ FoxP3+ regulatory T cells was observed only in arm B (p=0.016). A significant upregulation of PD-1 on sTILs was found in RD of pts enrolled in arm B (p=0.012), while programmed death-ligand 1 (PD-L1) was significantly overexpressed in residual tumors of arm A (p=0.02). A strong negative correlation was reported in arm B between expression of PD-L1 on pretreatment sTILs and CD3 expression on sTILs in RD (τ: -0.73). Grade≥3 AE incidence rates were similar between the two arms.

CONCLUSIONS

SC trastuzumab induced relevant sTILs enrichment, with favorable variations of immune parameters in HER2-positive BC pts with RD after NAT. Novel immunotherapy strategies should be tested to achieve SC-specific, antitumor immune response.

TRIAL REGISTRATION NUMBER

NCT03144947, and EudraCT number: 2016-000435-41.

Anti-Cancer Potential of Transiently Transfected HER2-Specific Human Mixed CAR-T and NK Cell Populations in Experimental Models: Initial Studies on Fucosylated Chondroitin Sulfate Usage for Safer Treatment

Human epidermal growth factor receptor 2 (HER2) is overexpressed in numerous cancer cell types. Therapeutic antibodies and chimeric antigen receptors (CARs) against HER2 were developed to treat human tumors. The major limitation of anti-HER2 CAR-T lymphocyte therapy is attributable to the low HER2 expression in a wide range of normal tissues. Thus, side effects are caused by CAR lymphocyte "on-target off-tumor" reactions. We aimed to develop safer HER2-targeting CAR-based therapy. CAR constructs against HER2 tumor-associated antigen (TAA) for transient expression were delivered into target T and natural killer (NK) cells by an effective and safe non-viral transfection method via nucleofection, excluding the risk of mutations associated with viral transduction. Different in vitro end-point and real-time assays of the CAR lymphocyte antitumor cytotoxicity and in vivo human HER2-positive tumor xenograft mice model proved potent cytotoxic activity of the generated CAR-T-NK cells. Our data suggest transient expression of anti-HER2 CARs in plasmid vectors by human lymphocytes as a safer treatment for HER2-positive human cancers. We also conducted preliminary investigations to elucidate if fucosylated chondroitin sulfate may be used as a possible agent to decrease excessive cytokine production without negative impact on the CAR lymphocyte antitumor effect.

Therapies beyond Physiological Barriers and Drug Resistance: A Pilot Study and Review of the Literature Investigating If Intrathecal Trastuzumab and New Treatment Options Can Improve Oncologic Outcomes in Leptomeningeal Metastases from HER2-Positive Breast Cancer

Leptomeningeal metastases (LM) are a rare but rapidly fatal complication defined by the spread of tumor cells within the leptomeninges and the subarachnoid space, found in approximately 10% of patients with HER2-positive breast cancers. This pilot study evaluated the efficacy of local treatment with intrathecal Trastuzumab (IT) added to systemic treatment. The oncologic outcome of 14 patients with HER2-positive LM is reported. Seven received IT, and seven received standard of care (SOC). The mean number of IT cycles administered was 12.14 ± 4.00. The response rate to CNS after IT treatment + SOC was 71.4%, and three patients (42.8%) obtained durable responses lasting more than 12 months. The median progression-free survival (mPFS) after LM diagnosis was six months, and the median overall survival (mOS) was ten months. The mean values of the PFS in favor of IT therapy (10.6 mo vs. 6.6 mo) and OS (13.7 vs. 9.3 mo) suggest a non-negligible investigation direction in the sense of exploiting intrathecal administration as a possible treatment modality in these patients. Adverse events reported were local pain related to intrathecal administration and one case of arachnoiditis, hematoma, and CSF fistulae. Intrathecal administration of Trastuzumab, alongside systemic treatment and radiotherapy, might improve oncologic outcomes in LM HER2-positive breast cancer with manageable toxicity.

Dual neoadjuvant blockade plus chemotherapy versus monotherapy for the treatment of women with non-metastatic HER2-positive breast cancer: a systematic review and meta-analysis

BACKGROUND

We aimed to determine the effect of dual anti-HER2 blockade compared to monotherapy on clinically important outcomes.

METHODS

We carried out a systematic review updated until July 2022. The outcomes included pathological complete response (pCR), clinical response, event-free survival, and overall survival.

RESULTS

We identified eleven randomized clinical trials (2836 patients). When comparing paclitaxel plus dual treatment versus paclitaxel plus trastuzumab or lapatinib, dual treatment was associated with a higher probability of achieving a pathological complete response (OR 2.88, 95% CI 2.02-4.10). Addition of a taxane to an anthracycline plus cyclophosphamide and fluorouracil, plus lapatinib or trastuzumab, showed that the dual treatment was better than lapatinib alone (OR 2.47, 95% CI 1.41-4.34), or trastuzumab alone (OR 1.89, 95% CI 1.13-3.16). Dual treatment may result in an increase in survival outcomes and tumour clinical response, although such benefits are not consistent for all the combinations studied.

CONCLUSIONS

The use of dual blockade with combinations of trastuzumab and pertuzumab can be recommended for the neoadjuvant treatment of women with HER2-positive breast cancer. PROSPERO Registration number: CRD42018110273.

Pharmacodynamic Modeling Identifies Synergistic Interaction Between Chloroquine and Trastuzumab in Refractory HER2- positive Breast Cancer Cells

BACKGROUND/AIM

Despite improvements in HER2-positive breast cancer (BC) patients' outcomes with trastuzumab, the occurrence of intrinsic or acquired resistance presents a clinical challenge. Here, we quantitatively assess the combinatorial effects of chloroquine, an autophagy inhibitor, with trastuzumab on JIMT-1 cells, a HER2-positive BC cell-line primarily resistant to trastuzumab.

MATERIALS AND METHODS

The temporal changes in JIMT-1 cellular viability were assessed using the CCK-8 kit, where JIMT-1 cells were exposed for 72-h to trastuzumab (0.007-17.19 μM) or chloroquine (5-50 μM) as single-agents, in combination (trastuzumab: 0.007-0.688 μM; chloroquine: 5-15 μM), or control (no drug). Concentration-response relationships were built for each treatment arm to determine drugs' concentrations inducing 50% of cell-killing (IC50). Cellular pharmacodynamic models were built to characterize the time-trajectory of JIMT-1 cellular viability under each treatment arm. The nature of trastuzumab and chloroquine interaction was quantified by estimating the interaction parameter (Ψ).

RESULTS

The IC50 were estimated at 19.7 and 24.4 μM for trastuzumab and chloroquine. The maximum killing effect was about thrice higher for chloroquine than trastuzumab (0.0405 vs. 0.0125 h^-1), validating chloroquine's superior anti-cancer effect on JIMT-1 cells compared to trastuzumab. The time-delay for chloroquine cell-killing was twice longer than that for trastuzumab (17.7 vs. 7 h), suggesting a chloroquine time-dependent anti-cancer effect. The Ψ was determined at 0.529 (Ψ<1), indicating a synergistic interaction.

CONCLUSION

This proof-of-concept study on JIMT-1 cells identified chloroquine and trastuzumab synergistic interaction, warranting further in vivo investigations.

Trastuzumab-based near-infrared photoimmunotherapy in xenograft mouse of breast cancer

Near-infrared photoimmunotherapy (NIR-PIT) is a novel form of cancer treatment using conjugates of antibody against overexpressed antigens in cancers and photoabsorber IRDye700DX. HER2 is overexpressed in various cancers, for which molecular targeted therapy such as trastuzumab has been developed. The present study investigated the efficacy potential of HER2-targeted NIR-PIT using trastuzumab-IRDye700DX conjugate (Tra-IR700) in HER2-positive breast cancer. We first examined the reactivity of Tra-IR700 and the cytotoxicity of NIR-PIT in vitro. HER2-positive BT-474 and SK-BR-3 cells and HER2-negative BT-20 cells were used. Tra-IR700 fluorescence was only observed in HER2-positive breast cancer cell lines, and the fluorescence was localized to the cell surface. Furthermore, HER2-positive breast cancer cell lines treated with NIR-PIT showed swelling and blebbing shortly after irradiation, and eventually increased PI-positive dead cells. Next, tumor accumulation of Tra-IR700 and tumor damage by NIR-PIT were examined in vivo. Tra-IR700 was administered intravenously to a xenograft model in which BT-474 cells were implanted subcutaneously in BALB/c nude mice. Tra-IR700 fluorescence was the highest in tumor tissue 1 day after administration, and the fluorescence was localized to the cell membrane of tumor cells. At this time point, NIR-PIT resulted in diffuse necrosis of tumor tissues 1 day after irradiation. These results suggest that NIR-PIT with Tra-IR700 induces a highly selective therapeutic effect in a HER2-positive breast cancer model. NIR-PIT using Tra-IR700 is expected to be a novel treatment for HER2-positive cancers, including breast cancer.

STARD3: A New Biomarker in HER2-Positive Breast Cancer

Pathological complete response (pCR) after neoadjuvant systemic treatment (NST) is an important prognostic factor in HER2-positive breast cancer. The majority of HER2-positive breast cancers are amplified at the HER2 gene locus, several genes are co-amplified with HER2, and a subset of them are co-expressed. The STARD3 gene belongs to the HER2 amplicon, and its role as a predictive marker was never addressed. The objective of this study was to investigate the predictive value of STARD3 protein expression on NST pathological response in HER2-positive breast cancer. In addition, we studied the prognostic value of this marker.

METHODS

We conducted a retrospective study between 2007 and 2020 on 112 patients with non-metastatic HER2-positive breast cancer treated by NST and then by surgery. We developed an immunohistochemistry assay for STARD3 expression and subcellular localization and determined a score for STARD3-positivity. As STARD3 is an endosomal protein, its expression was considered positive if the intracellular signal pattern was granular.

RESULTS

In this series, pCR was achieved in half of the patients. STARD3 was positive in 86.6% of cases and was significantly associated with pCR in univariate analysis (p = 0.013) and after adjustment on other known pathological parameters (p = 0.044). Performances on pCR prediction showed high sensitivity (96%) and negative predictive value (87%), while specificity was 23% and positive predictive value was 56%. Overall, specific, relapse-free, and distant metastasis-free survivals were similar among STARD3 positive and negative groups, independently of other prognosis factors.

CONCLUSION

NST is an opportunity for HER2-positive cancers. In this series of over a hundred HER2-positive and non-metastatic patients, a STARD3-negative score was associated with the absence of pathological complete response. This study suggests that determining STARD3 overexpression status on initial biopsies of HER2-positive tumors is an added value for the management of a subset of patients with high probability of no pathological response.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.

First-Line Treatment of HER2-Positive Metastatic Breast Cancer With Dual Blockade Including Biosimilar Trastuzumab (SB3): Population-Based Real-World Data From the DBCG

Purpose

Dual blockade with trastuzumab and pertuzumab in combination with chemotherapy is the recommended first-line therapy for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC). The purpose of this retrospective study is to examine the clinical outcomes of the trastuzumab biosimilar SB3 in first-line dual blockade treatment using real-world data of patients with HER-positive mBC.

Methods

In Denmark, all women with breast cancer are registered in the database of the Danish Breast Cancer Group (DBCG). From this prospective observational registry, we extracted information on primary diagnosis and treatment of all women with HER2-positive mBC who received first-line treatment with SB3 and pertuzumab from September 1, 2018, to February 29, 2020. Retrospectively collected data from the DBCG database included information concerning treatment start, end, and reason for discontinuation. The primary endpoints for the study were overall survival (OS) and progression-free survival (PFS).

Results

The study included 117 women who received first-line treatment with SB3 and pertuzumab for their HER2-positive mBC. The study population had a mean age of 60 years. A total of 71 patients (61%) had recurrent disease and 46 patients (39%) presented with de novo mBC. The median follow-up was 11.1 and 15.4 months for PFS and OS, respectively. At 12 months, OS was 84% (95% confidence interval [CI], 78-91), whereas the median OS was not reached. The median PFS was 12.7 months (95% CI, 11.1-16.2). Median time on treatment was 8.7 months (95% CI, 7.6-11.4); 36 patients (31%) were still on treatment at end of study.

Conclusions

This retrospective real-world, nationwide study demonstrated comparable median PFS to the historical data of using reference trastuzumab and pertuzumab as first-line dual blockade.

MUC1 is a potential target to overcome trastuzumab resistance in breast cancer therapy

Although resistance is its major obstacle in cancer therapy, trastuzumab is the most successful agent in treating epidermal growth factor receptor 2 positive (HER2 +) breast cancer (BC). Some patients show resistance to trastuzumab, and scientists want to circumvent this problem. This review elaborately discusses possible resistance mechanisms to trastuzumab and introduces mucin 1 (MUC1) as a potential target efficient for overcoming such resistance. MUC1 belongs to the mucin family, playing the oncogenic/mitogenic roles in cancer cells and interacting with several other oncogenic receptors and pathways, such as HER2, β-catenin, NF-κB, and estrogen receptor (ERα). Besides, it has been established that MUC1- Cytoplasmic Domain (MUC1-CD) accelerates the development of resistance to trastuzumab and that silencing MUC1-C proto-oncogene is associated with increased sensitivity of HER2⁺ cells to trastuzumab-induced growth inhibitors. We mention why targeting MUC1 can be useful in overcoming trastuzumab resistance in cancer therapy.

Anticancer Activity of Ω-6 Fatty Acids through Increased 4-HNE in Breast Cancer Cells

Simple Summary

Epidemiological evidence suggests that breast cancer risk is lowered by Ω-3 and increased by Ω-6 polyunsaturated fatty acids (PUFAs). Paradoxically, the Ω-6 PUFA metabolite 4-hydroxynonenal (4-HNE) inhibits cancer cell growth. This duality prompted us to study whether arachidonic acid (AA) would enhance doxorubicin (dox) cytotoxicity towards breast cancer cells. We found that supplementing AA or inhibiting 4-HNE metabolism potentiated doxorubicin (dox) toxicity toward Her2-dependent breast cancer but spared myocardial cells. Our results suggest that Ω-6 PUFAs could improve outcomes of dox chemotherapy in Her2-overexpressing breast cancer.

Abstract

Her2-amplified breast cancers resistant to available Her2-targeted therapeutics continue to be a challenge in breast cancer therapy. Dox is the mainstay of chemotherapy of all types of breast cancer, but its usefulness is limited by cumulative cardiotoxicity. Because oxidative stress caused by dox generates the pro-apoptotic Ω-6 PUFA metabolite 4-hydroxynonenal (4-HNE), we surmised that Ω-6 PUFAs would increase the effectiveness of dox chemotherapy. Since the mercapturic acid pathway enzyme RALBP1 (also known as RLIP76 or Rlip) that limits cellular accumulation of 4-HNE also mediates dox resistance, the combination of Ω-6 PUFAs and Rlip depletion could synergistically improve the efficacy of dox. Thus, we studied the effects of the Ω-6 PUFA arachidonic acid (AA) and Rlip knockdown on the antineoplastic activity of dox towards Her2-amplified breast cancer cell lines SK-BR-3, which is sensitive to Her2 inhibitors, and AU565, which is resistant. AA increased lipid peroxidation, 4-HNE generation, apoptosis, cellular dox concentration and dox cytotoxicity in both cell lines while sparing cultured immortalized cardiomyocyte cells. The known functions of Rlip including clathrin-dependent endocytosis and dox efflux were inhibited by AA. Our results support a model in which 4-HNE generated by AA overwhelms the capacity of Rlip to defend against apoptosis caused by dox or 4-HNE. We propose that Ω-6 PUFA supplementation could improve the efficacy of dox or Rlip inhibitors for treating Her2-amplified breast cancer.

A novel humanized MUC1 antibody-drug conjugate for the treatment of trastuzumab-resistant breast cancer

Mucin 1 (MUC1) has been regarded as an ideal target for cancer treatment, since it is overexpressed in a variety of different cancers including the majority of breast cancer. However, there are still no approved monoclonal antibody drugs targeting MUC1. In this study, we generated a humanized MUC1 (HzMUC1) antibody from our previously developed MUC1 mouse monoclonal antibody that only recognizes MUC1 on the surface of tumor cells. Furthermore, an antibody-drug conjugate (ADC) was generated by conjugating HzMUC1 with monomethyl auristatin (MMAE), and the efficacy of HzMUC1-MMAE on the MUC1-positive HER2+ breast cancer in vitro and in 'Xenograft' model was tested. Results from western blot analysis and immunoprecipitation revealed that the HzMUC1 antibody did not recognize cell-free MUC1-N in sera from breast cancer patients. Confocal microscopy analysis showed that HzMUC1 antibody bound to MUC1 on the surface of breast cancer cells. Results from mapping experiments suggested that HzMUC1 may recognize an epitope present in the interaction region between MUC1-N and MUC1-C. Results from colony formation assay and flow cytometry demonstrated that HzMUC1-MMAE significantly inhibited cell growth by inducing G2/M cell cycle arrest and apoptosis in trastuzumab-resistant HER2-positive breast cancer cells. Meanwhile, HzMUC1-MMAE significantly reduced the growth of HCC1954 xenograft tumors by inhibiting cell proliferation and enhancing cell death. In conclusion, our results indicate that HzMUC1-ADC is a novel therapeutic drug that can overcome trastuzumab resistance of breast cancer. HzMUC1-ADC should also be an effective therapeutic drug for the treatment of different MUC1-positive cancers in clinic.

The C-terminal HSP90 inhibitor NCT-58 kills trastuzumab-resistant breast cancer stem-like cells

N-terminal HSP90 inhibitors in development have had issues arising from heat shock response (HSR) induction and off-target effects. We sought to investigate the capacity of NCT-58, a rationally-synthesized C-terminal HSP90 inhibitor, to kill trastuzumab-resistant HER2-positive breast cancer stem-like cells. NCT-58 does not induce the HSR due to its targeting of the C-terminal region and elicits anti-tumor activity via the simultaneous downregulation of HER family members as well as inhibition of Akt phosphorylation. NCT-58 kills the rapidly proliferating bulk tumor cells as well as the breast cancer stem-like population, coinciding with significant reductions in stem/progenitor markers and pluripotent transcription factors. NCT-58 treatment suppressed growth and angiogenesis in a trastuzumab-resistant xenograft model, concomitant with downregulation of ICD-HER2 and HSF-1/HSP70/HSP90. These findings warrant further investigation of NCT-58 to address trastuzumab resistance in heterogeneous HER2-positive cancers.

Probabilistic Boolean Modeling of Pre-clinical Tumor Models for Biomarker Identification in Cancer Drug Development

As high-throughput sequencing experiments become more widely used in pre-clinical and clinical settings, pharmacogenetic and pharmacogenomic biomarker development plays an increasingly important role in oncology drug development pipelines and programs. Consequently, computer-based learning approaches have entered into use at multiple stages in pre-clinical and clinical pipelines. However, few approaches are available to identify interpretable and implementable biomarkers of response early in the drug development process when only small pre-clinical data packages are available. To address the need for early-stage biomarker development using pre-clinical tumor models, we have adapted the previously published Probabilistic Target Inhibitor Map (PTIM) platform to the challenge of biomarker hypothesis development, and denoted this approach the Probabilistic Target Map-Biomarker (PTM-Biomarker). In this article, we detail the history and design philosophy of PTM-Biomarker, and present two case studies using the biomarker discovery tool to illustrate its utility in guiding cancer drug development. © 2021 Wiley Periodicals LLC.

Metabolite Biomarkers of Response (BoRs): Towards a fingerprint for the evolution of metastatic breast cancer

Breast cancer is the most common cancer in women worldwide and despite improved treatment strategies, it persists as the second leading cause of death of women globally. Overall prognosis drops drastically once the cancer has metastasized, which is also associated with resistance to therapy. The evolution from a localized breast cancer to metastatic disease is complex and multifactorial. Metabolic reprogramming is a pre-requisite for this transition. In this graphical review, we provide an overview of altered metabolic pathways observed in metastatic breast cancer (mBC) and detail how metabolite biomarkers could serve as a novel class of precision medicine tools to improve the diagnosis, monitoring, and treatment of mBC.

Kinase drug discovery 20 years after imatinib: progress and future directions

Protein kinases regulate nearly all aspects of cell life, and alterations in their expression, or mutations in their genes, cause cancer and other diseases. Here, we review the remarkable progress made over the past 20 years in improving the potency and specificity of small-molecule inhibitors of protein and lipid kinases, resulting in the approval of more than 70 new drugs since imatinib was approved in 2001. These compounds have had a significant impact on the way in which we now treat cancers and non-cancerous conditions. We discuss how the challenge of drug resistance to kinase inhibitors is being met and the future of kinase drug discovery.

Tamoxifen overcomes the trastuzumab-resistance of SK-BR-3 tumorspheres by targeting crosstalk between cytoplasmic estrogen receptor α and the EGFR/HER2 signaling pathway

Since trastuzumab-resistance remains a major obstacle to the successful treatment of HER2-positive breast cancer, a detailed understanding of the mechanisms responsible is required to direct future pharmacotherapeutic strategies. Recently, several studies have indicated that the quiescent natures of cancer stem cells contribute to treatment resistance and tumor recurrence. Thus, in this study, we investigated the mechanism underlying trastuzumab resistance in a quiescent cell population using tumorsphere cultures and explored better therapeutic strategies to overcome trastuzumab resistance in HER2-positive breast cancer patients. We observed that most cells in SK-BR-3 tumorspheres were quiescent, showing the accumulation of cells at the G0/G1 phase as compared to cells in monolayer culture. Furthermore, SK-BR-3 tumorspheres exhibited enhanced EGFR/HER2 signaling, which was incompletely inhibited by trastuzumab, and subsequently led to trastuzumab-resistance. Interestingly, cytoplasmic estrogen receptor α (ERα) expression was markedly elevated in tumorspheres and was associated with enhanced EGFR/HER2 signaling. Accordingly, inhibition of ERα with tamoxifen selectively targeted tumorspheres rather than cells in monolayer culture and overcame trastuzumab resistance in tumorspheres. Taken together, our findings indicate that crosstalk between cytoplasmic ERα and the HER2/EGFR signaling pathway can be considered a novel therapeutic target for quiescent cell populations within HER2-positive breast cancer and that simultaneous inhibition of ER and the EGFR/HER2 pathway may prevent trastuzumab resistance. We hope that these results provide a basis for the use of combinations of tamoxifen and trastuzumab in HER2-positive breast cancer patients.

Recent Advances in Quenchbody, a Fluorescent Immunosensor

The detection of viruses, disease biomarkers, physiologically active substances, drugs, and chemicals is of great significance in many areas of our lives. Immunodetection technology is based on the specificity and affinity of antigen–antibody reactions. Compared with other analytical methods such as liquid chromatography coupled with mass spectrometry, which requires a large and expensive instrument, immunodetection has the advantages of simplicity and good selectivity and is thus widely used in disease diagnosis and food/environmental monitoring. Quenchbody (Q-body), a new type of fluorescent immunosensor, is an antibody fragment labeled with fluorescent dyes. When the Q-body binds to its antigen, the fluorescence intensity increases. The detection of antigens by changes in fluorescence intensity is simple, easy to operate, and highly sensitive. This review comprehensively discusses the principle, construction, application, and current progress related to Q-bodies.

Improved therapeutic efficacy of unmodified anti-tumor antibodies by immune checkpoint blockade and kinase targeted therapy in mouse models of melanoma

The use of specific anti-tumor antibodies has transformed the solid cancer therapeutics landscape with the relative successes of therapies such as anti-HER2 in breast cancer, and anti-EGFR in HNSCC and colorectal cancer. However, these therapies result in toxicity and the emergence of resistant tumors. Here, we showed that removing immune suppression and enhancing stimulatory signals increased the anti-tumor activity of unmodified TA99 antibodies (anti-TYRP1) with a significant reduction of growth of solid tumors and lung metastases in mouse models of melanoma. Immune checkpoint blockade enhanced the efficacy of TA99, which was associated with greater CD8⁺/Foxp3⁺, NK1.1⁺ and dendritic cell infiltrates, suggestive of an increased anti-tumor innate and adaptive immune responses. Further, MEK inhibition in melanoma cell lines increased the expression of melanosomal antigens in vitro, and combining TA99 and MEKi in vivo resulted in enhanced tumor control. Moreover, we found an improved therapeutic effect when YUMM tumor-bearing mice were treated with TA99 combined with MEKi and immune checkpoint blockade (anti-PD1 and anti-CTLA4). Our findings suggest that MEKi induced an increased expression of tumor-associated antigens, which in combination with anti-tumor antibodies, generated a robust adaptive anti-tumor response that was sustained by immune checkpoint inhibition therapy. We postulate that combining anti-tumor antibodies with standard-of-care strategies such as immune checkpoint blockade or targeted therapy, will improve therapeutic outcomes in cancer.

Molecular Mechanism of HER2 Rapid Internalization and Redirected Trafficking Induced by Anti-HER2 Biparatopic Antibody

Amplification and overexpression of HER2 (human epidermal growth factor receptor 2), an ErbB2 receptor tyrosine kinase, have been implicated in human cancer and metastasis. A bispecific tetravalent anti-HER2 antibody (anti-HER2-Bs), targeting two non-overlapping epitopes on HER2 in domain IV (trastuzumab) and domain II (39S), has been reported to induce rapid internalization and efficient degradation of HER2 receptors. In this study, we investigated the molecular mechanism of this antibody-induced rapid HER2 internalization and intracellular trafficking. Using quantitative fluorescent imaging, we compared the internalization kinetics of anti-HER2-Bs and its parental arm antibodies, alone or in combinations and under various internalization-promoting conditions. The results demonstrated that concurrent engagement of both epitopes was necessary for rapid anti-HER2-Bs internalization. Cellular uptake of anti-HER2-Bs and parental arm antibodies occurred via clathrin-dependent endocytosis; however, inside the cells antibodies directed different trafficking pathways. Trastuzumab dissociated from HER2 in 2 h, enabling the receptor to recycle, whereas anti-HER2-Bs stayed associated with the receptor throughout the entire endocytic pathway, promoting receptor ubiquitination, trafficking to the lysosomes, and efficient degradation. Consistent with routing HER2 to degradation, anti-HER2-Bs significantly reduced HER2 shedding and altered its exosomal export. Collectively, these results enable a better understanding of the mechanism of action of anti-Her2-Bs and can guide the rational design of anti-HER2 therapeutics as well as other bispecific molecules.

The Hippo Pathway Transducers YAP1/TEAD Induce Acquired Resistance to Trastuzumab in HER2-Positive Breast Cancer

Trastuzumab is the first-line targeted therapeutic drug for HER2-positive breast cancer, leading to improved overall survival. However, acquired resistance inevitably occurs. We aimed to identify, quantify, and assess the mechanisms of acquired resistance to trastuzumab. We established an acquired trastuzumab-resistant model in vitro from BT-474, a trastuzumab-sensitive, HER2-amplified breast-cancer cell line. A multi-omic strategy was implemented to obtain gene, proteome, and phosphoproteome signatures associated with acquired resistance to trastuzumab in HER2-positive breast cancer, followed by validation in human clinical samples. YAP1 dephosphorylation and TEAD2 overexpression were detected as significant alterations in the Hippo pathway in trastuzumab-resistant breast cancer. Because of the emerging role of these proteins as mediators of normal growth and tumorigenesis, we assessed the exogenous modulation of their activity, either by in vitro gene silencing or by pharmacological inhibition of the YAP1/TEAD complexes, both in vitro and in vivo. Moreover, we identified increased signaling through the Hippo pathway in human samples after progression following trastuzumab treatment. Finally, YAP1/TAZ nuclear accumulation in malignant cells in HER2 breast tumor was significantly associated with worse progression-free and overall survival in metastatic HER2-positive breast-cancer patients. Our results suggest the involvement of Hippo signaling in acquired trastuzumab resistance in breast cancer. Additionally, we provide novel evidence for a potential breast-cancer treatment strategy based on dual targeting of HER2 and Hippo pathway effectors, which may improve the antitumor activity of trastuzumab and help overcome resistance.

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.

Detection and destruction of HER2-positive cancer cells by Ultra Quenchbody-siRNA complex

Ultra Quenchbody (UQ-body) is a biosensor that utilizes the quenching behavior of the fluorescent dye linked to the antibody V region. When the corresponding antigen is bound to the UQ-body, the fluorescence is restored and allows the detection of target molecules easily and sensitively. In this paper, we constructed UQ-bodies to sensitively detect the human epidermal growth factor receptor 2 (HER2) cancer marker in solution or on cancer cells, which was further used to kill the cancer cells. A synthetic Fab fragment of anti-HER2 antibody Fab37 with many Trp residues at hypervariable region was prepared and labeled with fluorescent dyes to obtain the UQ-bodies. The UQ-body could detect HER2 in solution at concentrations as low as 20 pM with an EC₅₀ of 0.3 nM with a fourfold response. Fluorescence imaging of HER2-positive cells was successfully performed without any washing steps. To deliver small interfering RNA (siRNA) to cancer cells, a modified UQ-body with C-terminal 9R sequence was also prepared. HER2-positive cancer cells were effectively killed by polo-like kinase 1 siRNA intracellularly delivered by the UQ-body-9R. The novel approach employing siRNA-empowered UQ-body could detect and image the HER2 antigen easily and sensitively, and effectively kill the HER2-positive cancer cells.

Overcome trastuzumab resistance of breast cancer using anti-HER2 chimeric antigen receptor T cells and PD1 blockade

Trastuzumab-resistance is still a major challenge in treating patients with HER2 positive breast cancer. In this study, we tried to overcome transtuzumab-resistance by examining the therapeutic efficacy of third generation anti-HER2 chimeric antigen receptor (CAR)-T cells alone and in combination with PD1 blockade against HER2 positive and trastuzumab-resistance breast cancer cells in vitro and xenograft model. The anti-HER2 CAR-T cells were generated by infecting CD3/CD28 activated peripheral blood mononuclear cells with lentivirus expressing third generation anti-HER2 CAR. Anti-HER2 CAR-T cells were specifically targeted to HER2 positive BT474 and trastuzumab resistant HCC1954 cells compared with HER2 negative breast cancer cells. Results from ELISA revealed that the secretion of IL-2 and IFN-γ was increased in anti-HER2 CAR-T cells after being co-cultured with HCC1954 cells, and was further increased with the addition of anti-PD1 antibody in the co-culture system. Furthermore, data from lactate dehydrogenase assay showed that anti-HER2 CAR-T cells displayed a potent cytotoxicity against HCC1954 and BT474 cells. Addition of anti-PD1 antibody further enhanced the cytotoxicity of anti-HER2 CAR-T cells against HCC1954 cells. Lastly, injection of anti-HER2 CAR-T cells significantly reduced the growth of HCC1954 xenograft tumors. Combining anti-HER2 CAR-T cells with anti-PD1 antibody further impaired the growth of HCC1954 tumors. The present results indicate that anti-HER2 CAR-T cells have therapeutic efficacy against trastuzumab resistant breast tumors and addition of the PD1 antibody can further enhance the therapeutic effect of anti-HER2 CAR-T cells. Thus, third generation anti-HER2 CAR-T cells along with PD1 blockade is a potential therapy to overcome trastuzumab resistance of breast cancer.

Neoadjuvant neratinib promotes ferroptosis and inhibits brain metastasis in a novel syngeneic model of spontaneous HER2+ve breast cancer metastasis

Background

Human epidermal growth factor receptor-2 (HER2)-targeted therapies prolong survival in HER2-positive breast cancer patients. Benefit stems primarily from improved control of systemic disease, but up to 50% of patients progress to incurable brain metastases due to acquired resistance and/or limited permeability of inhibitors across the blood-brain barrier. Neratinib, a potent irreversible pan-tyrosine kinase inhibitor, prolongs disease-free survival in the extended adjuvant setting, and several trials evaluating its efficacy alone or combination with other inhibitors in early and advanced HER2-positive breast cancer patients are ongoing. However, its efficacy as a first-line therapy against HER2-positive breast cancer brain metastasis has not been fully explored, in part due to the lack of relevant pre-clinical models that faithfully recapitulate this disease. Here, we describe the development and characterisation of a novel syngeneic model of spontaneous HER2-positive breast cancer brain metastasis (TBCP-1) and its use to evaluate the efficacy and mechanism of action of neratinib.

Methods

TBCP-1 cells were derived from a spontaneous BALB/C mouse mammary tumour and characterised for hormone receptors and HER2 expression by flow cytometry, immunoblotting and immunohistochemistry. Neratinib was evaluated in vitro and in vivo in the metastatic and neoadjuvant setting. Its mechanism of action was examined by transcriptomic profiling, function inhibition assays and immunoblotting.

Results

TBCP-1 cells naturally express high levels of HER2 but lack expression of hormone receptors. TBCP-1 tumours maintain a HER2-positive phenotype in vivo and give rise to a high incidence of spontaneous and experimental metastases in the brain and other organs. Cell proliferation/viability in vitro is inhibited by neratinib and by other HER2 inhibitors, but not by anti-oestrogens, indicating phenotypic and functional similarities to human HER2-positive breast cancer. Mechanistically, neratinib promotes a non-apoptotic form of cell death termed ferroptosis. Importantly, metastasis assays demonstrate that neratinib potently inhibits tumour growth and metastasis, including to the brain, and prolongs survival, particularly when used as a neoadjuvant therapy.

Conclusions

The TBCP-1 model recapitulates the spontaneous spread of HER2-positive breast cancer to the brain seen in patients and provides a unique tool to identify novel therapeutics and biomarkers. Neratinib-induced ferroptosis provides new opportunities for therapeutic intervention. Further evaluation of neratinib neoadjuvant therapy is warranted.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1177-1) contains supplementary material, which is available to authorized users.

The chromodomain helicase CHD4 regulates ERBB2 signaling pathway and autophagy in ERBB2+ breast cancer cells

The chromodomain helicase DNA-binding 4 (CHD4), a member of the nucleosome remodeling and deacetylases (NuRD) complex, has been identified as an oncogene that modulates proliferation and migration of breast cancers (BC). ERBB2 is an oncogenic driver in 20–30% of BC in which its overexpression leads to increased chemoresistance. Here we investigated whether CHD4 depletion affects the ERBB2 cascade and autophagy, which represents a mechanism of resistance against Trastuzumab (Tz), a therapeutic anti-ERBB2 antibody. We show that CHD4 depletion in two ERBB2⁺ BC cell lines strongly inhibits cell proliferation, induces p27^KIP1 upregulation, Tyr¹²⁴⁸ ERBB2 phosphorylation, ERK1/2 and AKT dephosphorylation, and downregulation of both ERBB2 and PI3K levels. Moreover, CHD4 silencing impairs late stages of autophagy, resulting in increased levels of LC3 II and SQSTM1/p62, lysosomal enlargement and accumulation of autolysosomes (ALs). Importantly, we show that CHD4 depletion and concomitant treatment with Tz prevent cell proliferation in vitro. Our results suggest that CHD4 plays a critical role in modulating cell proliferation, ERBB2 signaling cascade and autophagy and provide new insights on CHD4 as a potential target for the treatment of ERBB2⁺ BC.

Summary: Inhibition of CHD4 expression impairs cell proliferation and survival through downregulation of ERBB2 signaling and block of autophagy. Therefore, CHD4 should be considered a potential target in ERBB2⁺ breast cancers.

A significant response to a combination of trastuzumab and vinorelbine in HER2-negative metastatic breast cancer with HER2 V777L mutation

Metastatic breast cancer (MBC) is the most life-threatening disease in women worldwide. HER2-mutated breast carcinoma has been reported to benefit from HER2-targeted tyrosine kinase inhibitors recently. Here, we presented a heavy pretreated and harbored HER2 V777L mutation de novo stage IV Luminal B (HER2 unamplified) breast cancer patient who achieved an unexpected good response to trastuzumab combined with vinorelbine therapy. Although HER2-unamplified MBC patients do not regularly benefit from anti-HER2 target therapy, HER2 V777L mutation detected by next-generation sequencing from ctDNA may present as a predictive biomarker for anti-HER2-based strategy therapy in HER2-negative MBC patients.

Label-Free Quantitative Proteomics Combined with Biological Validation Reveals Activation of Wnt/β-Catenin Pathway Contributing to Trastuzumab Resistance in Gastric Cancer

Resistance to trastuzumab, which specifically target HER2-positive breast and gastric cancer, can develop ultimately in cancer patients. However, the underlying mechanisms of resistance in gastric cancer have not been fully elucidated. Here, we established trastuzumab-resistant MKN45 and NCI N87 gastric cancer sublines from their parental cells. The resistant cells exhibited characteristics of epithelial-mesenchymal transition (EMT) and acquired higher migratory and invasive capacities. To exploit the activated pathways and develop new strategies to overcome trastuzumab resistance, we investigated MKN45 and MKN45/R cells via label-free quantitative proteomics, and found pathways that were altered significantly in MKN45/R cells, with the Wnt/β-catenin pathway being the most significant. We further confirmed the activation of this pathway by detecting its key molecules in MKN45/R and NCI N87/R cells via Western blot, in which Wnt3A, FZD6, and CTNNB1 increased, whereas GSK-3β decreased, manifesting the activation of the Wnt/β-catenin pathway. Correspondingly, inhibition of Wnt/β-catenin pathway by ICG-001, a specific Wnt/β-catenin inhibitor, preferentially reduced proliferation and invasion of trastuzumab-resistant cells and reversed EMT. Concurringly, CTNNB1 knockdown in stable cell lines potently sensitized cells to trastuzumab and induced more apoptosis. Taken together, our study demonstrates that the Wnt/β-catenin pathway mediates trastuzumab resistance, and the combination of Wnt/β-catenin inhibitors with trastuzumab may be an effective treatment option.

Human Epidermal Growth Factor Receptor 2-Targeted PET/Single- Photon Emission Computed Tomography Imaging of Breast Cancer: Noninvasive Measurement of a Biomarker Integral to Tumor Treatment and Prognosis

Increased human epidermal growth factor receptor 2 (HER2) expression is a hallmark of aggressive breast cancer. Imaging modalities have the potential to diagnose HER2-positive breast cancer and detect distant metastases. The heterogeneity of HER2 expression between primary and metastatic disease sites limits the value of tumor biopsies. Molecular imaging is a noninvasive tool to assess HER2-positive primary lesions and metastases. Radiolabeled antibodies, antibody fragments, and affibody molecules devise a reliable and quantitative method for detecting HER2-positive cancer using PET. HER2-targeted PET imaging is a valuable clinical tool with respect to both the care and maintenance of patients with breast cancer.

Trends involving monoclonal antibody (mAb) research and commercialization: A scientometric analysis of IMS Lifecycle R&D Focus Database (1980-2016)

This article aims to explore the trends of monoclonal antibodies (mAbs) research and commercialization, mainly to examine the development trajectories by a contrastive exploration of successful and unsuccessful mAb. This work is based on two sets of R&D project reports, consisting of 517 discontinued mAb project reports and 64 marketed mAb project reports, from IMS Lifecycle R&D Focus. The analysis of drug development processes will provide the basic evidences of mAb technology commercialization. We examined the mAb research and commercialization from three perspectives: (1) Countries with mAb research activity; (2) Organizations participating in mAb research and development; and (3) Clusters of keywords (indication and class description) regarding mAb. The technology factor, the market factor and the abilities of participating firms to pursue commercialization were analyzed. Through data analysis, we have discovered that the research and development on mAb has reached a mature and diversified stage.

Antibody-dependent fragmentation is a newly identified mechanism of cell killing in vivo

The prevailing view is that therapeutic antibodies deplete cells through opsonization and subsequent phagocytosis, complement-dependent lysis or antibody-dependent cellular-cytotoxicity. We used high resolution in vivo imaging to identify a new antibody-dependent cell death pathway where Kupffer cells ripped large fragments off crawling antibody-coated iNKT cells. This antibody-dependent fragmentation process resulted in lethality and depletion of crawling iNKT cells in the liver sinusoids and lung capillaries. iNKT cell depletion was Fcy-receptor dependent and required iNKT cell crawling. Blood, spleen or joint iNKT cells that did not crawl were not depleted. The antibody required high glycosylation for sufficiently strong binding of the iNKT cells to the Fc Receptors on Kupffer cells. Using an acetaminophen overdose model, this approach functionally depleted hepatic iNKT cells and affected the severity of liver injury. This study reveals a new mechanism of antibody-dependent killing in vivo and raises implications for the design of new antibodies for cancer and auto-reactive immune cells.

Tyrosine kinase inhibitors as modulators of trastuzumab-mediated antibody-dependent cell-mediated cytotoxicity in breast cancer cell lines

BACKGROUND

Trastuzumab is an anti-HER2 monoclonal antibody (mAb) therapy capable of antibody-dependent cell-mediated cytotoxicity (ADCC) and used in the treatment of HER2+ breast cancer. Through interactions with FcƴR+ immune cell subsets, trastuzumab functions as a passive immunotherapy. The EGFR/HER2-targeting tyrosine kinase inhibitor (TKI) lapatinib and the next generation TKIs afatinib and neratinib, can alter HER2 levels, potentially modulating the ADCC response to trastuzumab. Using LDH-release assays, we investigated the impact of antigen modulation, assay duration and peripheral blood mononuclear cell (PBMC) activity on trastuzumab-mediated ADCC in breast cancer models of maximal (SKBR3) and minimal (MCF-7) target antigen expression to determine if modulating the ADCC response to trastuzumab using TKIs may be a viable approach for enhancing tumor immune reactivity.

METHODS

HER2 levels were determined in lapatinib, afatinib and neratinib-treated SKBR3 and MCF-7 using high content analysis (HCA). Trastuzumab-mediated ADCC was assessed following treatment with TKIs utilising a colorimetric LDH release-based protocol at 4 and 12h timepoints. PBMC activity was assessed against non-MHC-restricted K562 cells. A flow cytometry-based method (CFSE/7-AAD) was also used to measure trastuzumab-mediated ADCC in medium-treated SKBR3 and MCF-7.

RESULTS

HER2 antigen levels were significantly altered by the three TKIs in both cell line models. The TKIs significantly reduced LDH levels directly in SKBR3 cells but not MCF-7. Lapatinib and neratinib augment trastuzumab-related ADCC in SKBR3 but the effect was not consistent with antigen expression levels and was dependent on volunteer PBMC activity (vs. K562). A 12h assay timepoint produced more consistent results. Trastuzumab-mediated ADCC (PBMC:target cell ratio of 10:1) was measured at 7.6±4.7% (T12) by LDH assay and 19±3.2 % (T12) using the flow cytometry-based method in the antigen-low model MCF-7.

CONCLUSIONS

In the presence of effector cells with high cytotoxic capacity, TKIs have the ability to augment the passive immunotherapeutic potential of trastuzumab in SKBR3, a model of HER2+ breast cancer. ADCC levels detected by LDH release assays are extremely low in MCF-7; the flow cytometry-based CFSE/7-AAD method is more sensitive and consistent for the determination of ADCC in HER2-low models.

Harnessing Integrative Omics to Facilitate Molecular Imaging of the Human Epidermal Growth Factor Receptor Family for Precision Medicine

Cancer is a growing problem worldwide. The cause of death in cancer patients is often due to treatment-resistant metastatic disease. Many molecularly targeted anticancer drugs have been developed against 'oncogenic driver' pathways. However, these treatments are usually only effective in properly selected patients. Resistance to molecularly targeted drugs through selective pressure on acquired mutations or molecular rewiring can hinder their effectiveness. This review summarizes how molecular imaging techniques can potentially facilitate the optimal implementation of targeted agents. Using the human epidermal growth factor receptor (HER) family as a model in (pre)clinical studies, we illustrate how molecular imaging may be employed to characterize whole body target expression as well as monitor drug effectiveness and the emergence of tumor resistance. We further discuss how an integrative omics discovery platform could guide the selection of 'effect sensors' - new molecular imaging targets - which are dynamic markers that indicate treatment effectiveness or resistance.

A 3D in vitro model of the human breast duct: a method to unravel myoepithelial-luminal interactions in the progression of breast cancer

Background

3D modelling fulfils a critical role in research, allowing for complex cell behaviour and interactions to be studied in physiomimetic conditions. With tissue banks becoming established for a number of cancers, researchers now have access to primary patient cells, providing the perfect building blocks to recreate and interrogate intricate cellular systems in the laboratory. The ducts of the human breast are composed of an inner layer of luminal cells supported by an outer layer of myoepithelial cells. In early-stage ductal carcinoma in situ, cancerous luminal cells are confined to the ductal space by an intact myoepithelial layer. Understanding the relationship between myoepithelial and luminal cells in the development of cancer is critical for the development of new therapies and prognostic markers. This requires the generation of new models that allows for the manipulation of these two cell types in a physiological setting.

Methods

Using access to the Breast Cancer Now Tissue Bank, we isolated pure populations of myoepithelial and luminal cells from human reduction mammoplasty specimens and placed them into 2D culture. These cells were infected with lentiviral particles encoding either fluorescent proteins, to facilitate cell tracking, or an inducible human epidermal growth factor receptor 2 (HER2) expression construct. Myoepithelial and luminal cells were then recombined in collagen gels, and the resulting cellular structures were analysed by confocal microscopy.

Results

Myoepithelial and luminal cells isolated from reduction mammoplasty specimens can be grown separately in 2D culture and retain their differentiated state. When recombined in collagen gels, these cells reform into physiologically reflective bilayer structures. Inducible expression of HER2 in the luminal compartment, once the bilayer has formed, leads to robust luminal filling, recapitulating ductal carcinoma in situ, and can be blocked with anti-HER2 therapies.

Conclusions

This model allows for the interaction between myoepithelial and luminal cells to be investigated in an in-vitro environment and paves the way to study early events in breast cancer development with the potential to act as a powerful drug discovery platform.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0843-4) contains supplementary material, which is available to authorized users.

Cellular glycosylation affects Herceptin binding and sensitivity of breast cancer cells to doxorubicin and growth factors

Alterations in protein glycosylation are a key feature of oncogenesis and have been shown to affect cancer cell behaviour perturbing cell adhesion, favouring cell migration and metastasis. This study investigated the effect of N-linked glycosylation on the binding of Herceptin to HER2 protein in breast cancer and on the sensitivity of cancer cells to the chemotherapeutic agent doxorubicin (DXR) and growth factors (EGF and IGF-1). The interaction between Herceptin and recombinant HER2 protein and cancer cell surfaces (on-rate/off-rate) was assessed using a quartz crystal microbalance biosensor revealing an increase in the accessibility of HER2 to Herceptin following deglycosylation of cell membrane proteins (deglycosylated cells B_max: 6.83 Hz; glycosylated cells B_max: 7.35 Hz). The sensitivity of cells to DXR and to growth factors was evaluated using an MTT assay. Maintenance of SKBR-3 cells in tunicamycin (an inhibitor of N-linked glycosylation) resulted in an increase in sensitivity to DXR (0.1 μM DXR P < 0.001) and a decrease in sensitivity to IGF-1 alone and to IGF-1 supplemented with EGF (P < 0.001). This report illustrates the importance of N-linked glycosylation in modulating the response of cancer cells to chemotherapeutic and biological treatments and highlights the potential of glycosylation inhibitors as future combination treatments for breast cancer.

Emerging trends and new developments in monoclonal antibodies: A scientometric analysis (1980-2016)

This article aims to explore the intellectual landscape of the study of monoclonal antibody (mAb), mainly to identify thematic trends, landmark articles and emerging trends involving mAb. This work is based on 4 sets of bibliographic records retrieved from the Web of Science. The final data set, consisting of 7,385 bibliographic records, was combined from the 4 individual data sets. This study explores the document co-citation clusters of 7,385 bibliographic records to identify the origin of mAb and the hot research specialty of this domain by applying CiteSpace software. We examined the mAb evolution from 4 perspectives: (1) Clusters of cited references regarding mAb; (2) Cited authors as contributors to mAb research; (3) Institutions participating in mAb research; and (4) Cited journals regarding mAb. The technical development, drug development and clinical applications of mAbs were analyzed. Through data analysis, we have identified the new directions for the exploration of mAbs, interactions between mAb technologies and diseases, and evolving global collaboration among institutions.

Trastuzumab in Human Epidermal Growth Factor Receptor 2-Positive Early Breast Cancer: Results of a Prospective, Noninterventional Study on Routine Treatment Between 2006 and 2012 in Germany

PURPOSE

Trastuzumab is part of the standard treatment in patients with human epidermal growth factor receptor 2-positive early breast cancer in addition to (neo)adjuvant chemotherapy. This German prospective noninterventional study, which included major patient cohorts underrepresented in the pivotal randomized studies, examined the generalizability of the results of those studies.

PATIENTS AND METHODS

Between 2006 and 2012, 4,027 patients were enrolled and treated with trastuzumab; they were unselected regarding age or concomitant/sequential adjuvant chemotherapy. Long-term outcome data were obtained in yearly intervals. All analyses were descriptive in nature.

RESULTS

Among 3,940 evaluable patients, 26% were elderly (older than 65 years of age). More than half of the population had pN0 tumor stage. Ninety-four percent received chemotherapy: 78% as adjuvant treatment and 14% as neoadjuvant treatment, 2% both. Anthracyclines were administered in 87% and taxanes in 66%. Trastuzumab was stopped prematurely in 9% (because of cardiotoxicity in 3.5%). Recurrence-free survival was 90.0% (95% confidence interval [CI], 88.9%-91.1%) and 82.8% (95% CI, 81.2%-84.4%) after 3 and 5 years, respectively. The corresponding figures for overall survival were 96.8% (95% CI, 96.1%-97.6%) and 90.0% (95% CI, 88.6%-91.4%). Pathological primary tumor size, lymph node involvement, and hormone receptor status had the greatest independent effect on recurrence risk. Cardiac function toxicity of National Cancer Institute common toxicity criteria grade ≥2 and ≥3 was observed in 2.5% and less than 1% of patients, respectively.

CONCLUSION

The maturing follow-up data seem to confirm the beneficial results of trastuzumab treatment for early breast cancer from the randomized studies. Moreover, these findings support use of trastuzumab-based therapy in patients groups less commonly included in the phase III trials (e.g., elderly patients and those with stage I disease). The Oncologist 2017;22:131-138Implications for Practice: On the basis of the results of large pivotal phase III studies, the inclusion of trastuzumab in adjuvant treatment regimens for human epidermal growth factor receptor 2-positive breast cancer is standard of care. However, in these trials, elderly patients, those with comorbidities, and/or those with contraindications or refusal of cytotoxic chemotherapy are typically underrepresented. This study provides data on observed treatment options, outcomes, and risks in a wider, unselected patient population (including more than 1,000 patients with stage I disease), treated routinely in several institutions of varying size and location across Germany.

Safety and efficacy of vinorelbine in combination with pertuzumab and trastuzumab for first-line treatment of patients with HER2-positive locally advanced or metastatic breast cancer: VELVET Cohort 1 final results

BACKGROUND

Pertuzumab, trastuzumab, and docetaxel is standard of care for first-line treatment of HER2-positive metastatic breast cancer (MBC). However, alternative chemotherapy partners are required to align with patient/physician preferences and to increase treatment flexibility. We report VELVET Cohort 1 results in which the efficacy and safety of pertuzumab and trastuzumab, administered sequentially in separate infusions, followed by vinorelbine, were evaluated. Cohort 2, where pertuzumab and trastuzumab were administered in a single infusion, followed by vinorelbine, recruited after Cohort 1 was fully enrolled, will be reported later.

METHODS

In this multicenter, two-cohort, open-label, phase II study, patients with HER2-positive locally advanced or MBC who had not received chemotherapy or biological therapy for their advanced disease received 3-weekly pertuzumab (840 mg loading, 420 mg maintenance doses) and trastuzumab (8 mg/kg loading, 6 mg/kg maintenance doses), followed by vinorelbine (25 mg/m² initial dose, 30-35 mg/m² maintenance doses) on days 1 and 8 or 2 and 9 of each 3-weekly cycle. Study treatment was given until investigator-assessed disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed objective response rate (ORR) in patients with measurable disease at baseline per RECIST v1.1. Secondary endpoints included progression-free survival (PFS) and safety.

RESULTS

Cohort 1 enrolled 106 patients. Investigator-assessed ORR was 74.2% (95% CI 63.8-82.9) in intent-to-treat patients with measurable disease (89/106 [84.0%]). Median PFS was 14.3 months (95% CI 11.2-17.5) in the intent-to-treat population. Treatment was reasonably well tolerated, with no unexpected toxicities. Diarrhea (61/106 patients [57.5%]) and neutropenia (54/106 [50.9%]) were the most common adverse events (AEs); neutropenia (33/106 [31.1%]) and leukopenia (14/106 [13.2%]) were the most common grade ≥3 AEs. Serious AEs were reported in 32/106 (30.2%) patients. AEs led to study drug discontinuation in 36/106 patients (34.0%). Eighteen of 106 patients (17.0%) had AEs suggestive of congestive heart failure; however, there were no confirmed cases.

CONCLUSIONS

The vinorelbine, pertuzumab, and trastuzumab combination is active and reasonably well tolerated. This regimen offers an alternative for patients who cannot receive docetaxel for first-line treatment of HER2-positive locally advanced or MBC.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01565083 , registered on 26 March 2012.

Clonal Evolutionary Analysis during HER2 Blockade in HER2-Positive Inflammatory Breast Cancer: A Phase II Open-Label Clinical Trial of Afatinib +/- Vinorelbine

BACKGROUND

Inflammatory breast cancer (IBC) is a rare, aggressive form of breast cancer associated with HER2 amplification, with high risk of metastasis and an estimated median survival of 2.9 y. We performed an open-label, single-arm phase II clinical trial (ClinicalTrials.gov NCT01325428) to investigate the efficacy and safety of afatinib, an irreversible ErbB family inhibitor, alone and in combination with vinorelbine in patients with HER2-positive IBC. This trial included prospectively planned exome analysis before and after afatinib monotherapy.

METHODS AND FINDINGS

HER2-positive IBC patients received afatinib 40 mg daily until progression, and thereafter afatinib 40 mg daily and intravenous vinorelbine 25 mg/m2 weekly. The primary endpoint was clinical benefit; secondary endpoints were objective response (OR), duration of OR, and progression-free survival (PFS). Of 26 patients treated with afatinib monotherapy, clinical benefit was achieved in 9 patients (35%), 0 of 7 trastuzumab-treated patients and 9 of 19 trastuzumab-naïve patients. Following disease progression, 10 patients received afatinib plus vinorelbine, and clinical benefit was achieved in 2 of 4 trastuzumab-treated and 0 of 6 trastuzumab-naïve patients. All patients had treatment-related adverse events (AEs). Whole-exome sequencing of tumour biopsies taken before treatment and following disease progression on afatinib monotherapy was performed to assess the mutational landscape of IBC and evolutionary trajectories during therapy. Compared to a cohort of The Cancer Genome Atlas (TCGA) patients with HER2-positive non-IBC, HER2-positive IBC patients had significantly higher mutational and neoantigenic burden, more frequent gain-of-function TP53 mutations and a recurrent 11q13.5 amplification overlapping PAK1. Planned exploratory analysis revealed that trastuzumab-naïve patients with tumours harbouring somatic activation of PI3K/Akt signalling had significantly shorter PFS compared to those without (p = 0.03). High genomic concordance between biopsies taken before and following afatinib resistance was observed with stable clonal structures in non-responding tumours, and evidence of branched evolution in 8 of 9 tumours analysed. Recruitment to the trial was terminated early following the LUX-Breast 1 trial, which showed that afatinib combined with vinorelbine had similar PFS and OR rates to trastuzumab plus vinorelbine but shorter overall survival (OS), and was less tolerable. The main limitations of this study are that the results should be interpreted with caution given the relatively small patient cohort and the potential for tumour sampling bias between pre- and post-treatment tumour biopsies.

CONCLUSIONS

Afatinib, with or without vinorelbine, showed activity in trastuzumab-naïve HER2-positive IBC patients in a planned subgroup analysis. HER2-positive IBC is characterized by frequent TP53 gain-of-function mutations and a high mutational burden. The high mutational load associated with HER2-positive IBC suggests a potential role for checkpoint inhibitor therapy in this disease.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01325428.

Anti-tubulin drugs conjugated to anti-ErbB antibodies selectively radiosensitize

Tumour resistance to radiotherapy remains a barrier to improving cancer patient outcomes. To overcome radioresistance, certain drugs have been found to sensitize cells to ionizing radiation (IR). In theory, more potent radiosensitizing drugs should increase tumour kill and improve patient outcomes. In practice, clinical utility of potent radiosensitizing drugs is curtailed by off-target side effects. Here we report potent anti-tubulin drugs conjugated to anti-ErbB antibodies selectively radiosensitize to tumours based on surface receptor expression. While two classes of potent anti-tubulins, auristatins and maytansinoids, indiscriminately radiosensitize tumour cells, conjugating these potent anti-tubulins to anti-ErbB antibodies restrict their radiosensitizing capacity. Of translational significance, we report that a clinically used maytansinoid ADC, ado-trastuzumab emtansine (T-DM1), with IR prolongs tumour control in target expressing HER2+ tumours but not target negative tumours. In contrast to ErbB signal inhibition, our findings establish an alternative therapeutic paradigm for ErbB-based radiosensitization using antibodies to restrict radiosensitizer delivery.

Drugs that sensitize tumour cells to ionizing radiation are prized because they can overcome resistance to radiotherapy. Here, the authors show that anti-tubulin drugs conjugated to cetuximab or trastuzumab can radiosensitize EGFR- or HER2-expressing tumors by increasing DNA damage and cell death due to ionizing radiation.

Research and development of therapeutic mAbs: An analysis based on pipeline projects

As the subject of active research and development (R&D) in recent decades, monoclonal antibodies have emerged among the major classes of therapeutic agents for treatment of many human diseases, especially cancers, infections, and immunological disorders. This article surveys the landscape of R&D projects of therapeutic monoclonal antibodies (mAbs), which are mostly used for disease immunotherapy, from a number of perspectives, including therapeutic indications, development phases, participants, and citation of related patents. The results of this research can be used as a reference resource for pharmaceutical researchers, investors, and policymakers in the field of therapeutic mAbs.

Consensus on precision medicine for metastatic cancers: a report from the MAP conference

Recent advances in biotechnologies have led to the development of multiplex genomic and proteomic analyses for clinical use. Nevertheless, guidelines are currently lacking to determine which molecular assays should be implemented in metastatic cancers. The first MAP conference was dedicated to exploring the use of genomics to better select therapies in the treatment of metastatic cancers. Sixteen consensus items were covered. There was a consensus that new technologies like next-generation sequencing of tumors and ddPCR on circulating free DNA have convincing analytical validity. Further work needs to be undertaken to establish the clinical utility of liquid biopsies and the added clinical value of expanding from individual gene tests into large gene panels. Experts agreed that standardized bioinformatics methods for biological interpretation of genomic data are needed and that precision medicine trials should be stratified based on the level of evidence available for the genomic alterations identified.

The combination of trastuzumab and pertuzumab administered at approved doses may delay development of trastuzumab resistance by additively enhancing antibody-dependent cell-mediated cytotoxicity

Although the recently concluded CLEOPATRA trial showed clinical benefits of combining trastuzumab and pertuzumab for treating HER2-positive metastatic breast cancer, trastuzumab monotherapy is still the mainstay in adjuvant settings. Since trastuzumab resistance occurs in over half of these cancers, we examined the mechanisms by which treatment of intrinsically trastuzumab-resistant and -sensitive tumors can benefit from the combination of these antibodies. F(ab′)₂ of both trastuzumab and pertuzumab were generated and validated in order to separately analyze antibody-dependent cell-mediated cytotoxicity (ADCC)-based and direct biological effects of the antibodies. Compared to monotherapy, combination of the two antibodies at clinically permitted doses enhanced the recruitment of natural killer cells responsible for ADCC, and significantly delayed the outgrowth of xenografts from intrinsically trastuzumab-resistant JIMT-1 cells. Antibody dose-response curves of in vitro ADCC showed that antibody-mediated killing can be saturated, and the two antibodies exert an additive effect at sub-saturation doses. Thus, the additive effect in vivo indicates that therapeutic tissue levels likely do not saturate ADCC. Additionally, isobole studies with the in vitro trastuzumab-sensitive BT-474 cells showed that the direct biological effect of combined treatment is additive, and surpasses the maximum effect of either monotherapy. Our results suggest the combined therapy is expected to give results that are superior to monotherapy, whatever the type of HER2-positive tumor may be. The combination of both antibodies at maximum clinically approved doses should thus be administered to patients to recruit maximum ADCC and cause maximum direct biological growth inhibition.