Diagnostics and Therapeutics in Targeting HER2 Breast Cancer: A Novel Approach

Innovations in Positron Emission Tomography and State of the Art in the Evaluation of Breast Cancer Treatment Response

The advent of hybrid Positron Emission Tomography/Computed Tomography (PET/CT) and PET/Magnetic Resonance Imaging (MRI) scanners resulted in an increased clinical relevance of nuclear medicine in oncology. The use of [18F]-Fluorodeoxyglucose ([18F]FDG) has also made it possible to study tumors (including breast cancer) from not only a dimensional perspective but also from a metabolic point of view. In particular, the use of [18F]FDG PET allowed early confirmation of the efficacy or failure of therapy. The purpose of this review was to assess the literature concerning the response to various therapies for different subtypes of breast cancer through PET. We start by summarizing studies that investigate the validation of PET/CT for the assessment of the response to therapy in breast cancer; then, we present studies that compare PET imaging (including PET devices dedicated to the breast) with CT and MRI, focusing on the identification of the most useful parameters obtainable from PET/CT. We also focus on novel non-FDG radiotracers, as they allow for the acquisition of information on specific aspects of the new therapies.

Computational design of newly engineered DARPins as HER2 receptor inhibitors for breast cancer treatment

Background and purpose

Human epidermal growth factor receptor 2 (HER2) is overexpressed in approximately 25% of breast cancer patients; therefore, its inhibition is a therapeutic target in cancer treatment.

Experimental approach

In this study, two new variants of designed ankyrin repeat proteins (DARPins), designated EG3-1 and EG3-2, were designed to increase their affinity for HER2 receptors. To this end, DARPin G3 was selected as a template, and six-point mutations comprising Q26E, I32V, T49A, L53H, K101R, and G124V were created on its structure. Furthermore, the 3D structures were formed through homology modeling and evaluated using molecular dynamic simulation. Then, both structures were docked to the HER2 receptor using the HADDOCK web tool, followed by 100 ns of molecular dynamics simulation for both DARPins / HER2 complexes.

Findings/Results

The theoretical result confirmed both structures' stability. Molecular dynamics simulations reveal that the applied mutations on DARPin EG3-2 significantly improve the receptor binding affinity of DARPin.

Conclusion and implications

The computationally engineered DARPin EG3-2 in this study could provide a hit compound for the design of promising anticancer agents targeting HER2 receptors.

Reviving a Classic Antigen with a Cutting-Edge Approach: Nanobodies for HER2+ Breast Cancer

The serendipitous discovery of nanobodies (NBs) around two decades ago opened the door to new possibilities for innovative strategies, particularly in cancer treatment. These antigen-binding fragments are derived from heavy-chain-only antibodies naturally found in the serum of camelids and sharks. NBs are an appealing agent for the progress of innovative therapeutic strategies because they combine the advantageous assets of smaller molecules and conventional monoclonal antibodies (mAbs). Moreover, the possibility to produce NBs using bacterial systems reduces manufacturing expenses and speeds up the production process, making them a feasible option for the development of new bio-drugs. Several NBs have been developed over the past 10 years and are currently being tested in clinical trials for various human targets. Here, we provide an overview of the notable structural and biochemical characteristics of NBs, particularly in their application against HER2, an extracellular receptor that often gets aberrantly activated during breast cancer tumorigenesis. The focus is on the recent advancements in diagnostic and therapeutic research up to the present date.

Preclinical and Basic Research Strategies for Overcoming Resistance to Targeted Therapies in HER2-Positive Breast Cancer

The amplification of epidermal growth factor receptor 2 (HER2) is associated with a poor prognosis and HER2 gene is overexpressed in approximately 15-30% of breast cancers. In HER2-positive breast cancer patients, HER2-targeted therapies improved clinical outcomes and survival rates. However, drug resistance to anti-HER2 drugs is almost unavoidable, leaving some patients with an unmet need for better prognoses. Therefore, exploring strategies to delay or revert drug resistance is urgent. In recent years, new targets and regimens have emerged continuously. This review discusses the fundamental mechanisms of drug resistance in the targeted therapies of HER2-positive breast cancer and summarizes recent research progress in this field, including preclinical and basic research studies.

ncRNA-mediated ceRNA regulatory network: Transcriptomic insights into breast cancer progression and treatment strategies

With the rapid development of next-generation sequencing technology, several studies have shown that ncRNAs can act as competitive endogenous RNAs (ceRNAs) and are involved in various biological processes, such as proliferation, differentiation, apoptosis, and migration of breast cancer (BC) cells, and plays an important role in BC progression as a molecular target for its diagnosis, treatment, prognosis, and differentiation of subtypes and age groups of BC patients. Based on the description of ceRNA-related biological functions, this study screened and sorted the sequencing analysis and experimental verification conclusions of BC-related ceRNAs and found that the ncRNAs mediated ceRNA networks can promote the development of BC by promoting the expression of genes related to BC proliferation, drug resistance, and apoptosis, inducing the production of epithelial-mesenchymal transition (EMT) to promote metastasis and activating cancer-related signaling pathways.

Nanobodies for the Early Detection of Ovarian Cancer

Ovarian cancer ranks fifth in cancer-related deaths among women. Since ovarian cancer patients are often asymptomatic, most patients are diagnosed only at an advanced stage of disease. This results in a 5-year survival rate below 50%, which is in strong contrast to a survival rate as high as 94% if detected and treated at an early stage. Monitoring serum biomarkers offers new possibilities to diagnose ovarian cancer at an early stage. In this study, nanobodies targeting the ovarian cancer biomarkers human epididymis protein 4 (HE4), secretory leukocyte protease inhibitor (SLPI), and progranulin (PGRN) were evaluated regarding their expression levels in bacterial systems, epitope binning, and antigen-binding affinity by enzyme-linked immunosorbent assay and surface plasmon resonance. The selected nanobodies possess strong binding affinities for their cognate antigens (K_D~0.1-10 nM) and therefore have a pronounced potential to detect ovarian cancer at an early stage. Moreover, it is of utmost importance that the limits of detection (LOD) for these biomarkers are in the pM range, implying high specificity and sensitivity, as demonstrated by values in human serum of 37 pM for HE4, 163 pM for SLPI, and 195 pM for PGRN. These nanobody candidates could thus pave the way towards multiplexed biosensors.

Molecular Imaging in Nanomedical Research 2.0

Over the last two decades, imaging techniques have become irreplaceable tools in nanotechnology: electron microscopy techniques are routinely used to observe the structural features of newly manufactured nanoconstructs, while light and electron microscopy, magnetic resonance imaging, optical imaging, positron emission tomography, and ultrasound imaging allow dynamic monitoring of the biodistribution, targeting and clearance of nanoparticulates in living systems, either for the whole organism or at the level of single cells, tissues and organs [...]

Homodimer 99mTc-HYNIC-E(SSSLTVPWY)2 peptide improved HER2-overexpressed tumor targeting and imaging

We hypothesized that a novel design of the LTVPWY (LY) peptide might exhibit a great potential for improving binding affinity and targeting HER2-overexpressed tumors. Hence, new dimer construction of ^99mTc-labeled LY [^99mTc-HYNIC-E(SSSLTVPWY)₂] (^99mTc-DLY) was introduced. Afterward, a head-to-head comparison of in vitro and in vivo experiments was performed between ^99mTc-DLY and ^99mTc-HYNIC-SSSLTVPWY as the monomer analog. The blocking dosage of trastuzumab reduced the uptake of the dimer about 20% more efficiently than the monomer in the SKOV-3 cell line. A twofold increase in competitive binding affinity and biological half-life was observed for ^99mTc-DLY. The ovarian-tumor-bearing mice were detected with high contrast where the tumor-to-muscle ratio of ^99mTc-DLY was notably increased about 40% using a gamma camera. The biodistribution experiment revealed an approximately 10% enhancement in tumor/blood, tumor/muscle, and tumor/bone ratios for the dimer. More rapid blood clearance was another achievement of the homodimer design. Overall, ^99mTc-DLY successfully affected the pharmacokinetics and consequently the visualization of HER2-overexpressing tumors.

HER-2-Targeted Nanoparticles for Breast Cancer Diagnosis and Treatment

Human epidermal growth factor receptor-2 (HER-2) overexpressing breast cancer is a breast cancer subtype characterized by high aggressiveness, high frequency of brain metastases and poor prognosis. HER-2, a glycoprotein belonging to the ErbB receptor family, is overexpressed on the outer membrane of cancer cells and has been an important therapeutic target for the development of targeted drugs, such as the monoclonal antibodies trastuzumab and pertuzumab. These therapies have been available in clinics for more than twenty years. However, despite the initial enthusiasm, a major issue emerged limiting HER-2 targeted therapy efficacy, i.e., the evolution of drug resistance, which could be tackled by nanotechnology. The aim of this review is to provide a first critical update on the different types of HER-2-targeted nanoparticles that have been proposed in the literature in the last decade for therapeutic purposes. We focus on the different targeting strategies that have been explored, their relative outcomes and current limitations that still need to be improved. Then, we review the nanotools developed as diagnostic kits, focusing on the most recent techniques, which allow accurate quantification of HER-2 levels in tissues, with the aim of promoting more personalized medicinal approaches in patients.

Targeting the COP9 signalosome for cancer therapy

The COP9 signalosome (CSN) is a highly conserved protein complex composed of 8 subunits (CSN1 to CSN8). The individual subunits of the CSN play essential roles in cell proliferation, tumorigenesis, cell cycle regulation, DNA damage repair, angiogenesis, and microenvironmental homeostasis. The CSN complex has an intrinsic metalloprotease that removes the ubiquitin-like activator NEDD8 from cullin-RING ligases (CRLs). Binding of neddylated CRLs to CSN is sensed by CSN4 and communicated to CSN5 with the assistance of CSN6, thus leading to the activation of deneddylase. Therefore, CSN is a crucial regulator at the intersection between neddylation and ubiquitination in cancer progression. Here, we summarize current understanding of the roles of individual CSN subunits in cancer progression. Furthermore, we explain how the CSN affects tumorigenesis through regulating transcription factors and the cell cycle. Finally, we discuss individual CSN subunits as potential therapeutic targets to provide new directions and strategies for cancer therapy.

Future of PD-1/PD-L1 axis modulation for the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) has the worst prognosis among the subtypes of breast cancer, with no targeted therapy available. Immunotherapy targeting programmed cell death protein-1 (PD-1) and its ligand (PD-L1) has resulted in some promising outcomes in cancer patients. The common treatments are monoclonal antibodies (mAbs). Despite novel methodologies in developing mAbs, there are several drawbacks with these medications. Immunological reactions, expensive and time-consuming production and requiring refrigeration are some of the challenging characteristics of mAbs that are addressed with using aptamers. Aptamers are nucleotide-based structures with high selectivity and specificity for target. Their small size helps aptamers penetrate the tissue better. In this review, we have discussed the nature of PD-1/PD-L1 interaction and summarised the available mAbs and aptamers specific for these two targets. This review highlights the role of aptamers as a future pathway for PD-1/PD-L1 modulation.

The Protein Landscape of Mucinous Ovarian Cancer: Towards a Theranostic

MOC is a rare histotype of epithelial ovarian cancer, and current management options are inadequate for the treatment of late stage or recurrent disease. A shift towards personalised medicines in ovarian cancer is being observed, with trials targeting specific molecular pathways, however, MOC lags due to its rarity. Theranostics is a rapidly evolving category of personalised medicine, encompassing both a diagnostic and therapeutic approach by recognising targets that are expressed highly in tumour tissue in order to deliver a therapeutic payload. The present review evaluates the protein landscape of MOC in recent immunohistochemical- and proteomic-based research, aiming to identify potential candidates for theranostic application. Fourteen proteins were selected based on cell membrane localisation: HER2, EGFR, FOLR1, RAC1, GPR158, CEACAM6, MUC16, PD-L1, NHE1, CEACAM5, MUC1, ACE2, GP2, and PTPRH. Optimal proteins to target using theranostic agents must exhibit high membrane expression on cancerous tissue with low expression on healthy tissue to afford improved disease outcomes with minimal off-target effects and toxicities. We provide guidelines to consider in the selection of a theranostic target for MOC and suggest future directions in evaluating the results of this review.