Antibody drug conjugates for treatment of breast cancer: Novel targets and diverse approaches in ADC design

Precision Medicine in Rheumatic Diseases: Unlocking the Potential of Antibody-Drug Conjugates

In the era of precision medicine, antibody-drug conjugates (ADCs) have emerged as a cutting-edge therapeutic strategy. These innovative compounds combine the precision of monoclonal antibodies with the potent cell-killing or immune-modulating abilities of attached drug payloads. This unique strategy not only reduces off-target toxicity but also enhances the therapeutic effectiveness of drugs. Beyond their well established role in oncology, ADCs are now showing promising potential in addressing the unmet needs in the therapeutics of rheumatic diseases. Rheumatic diseases, a diverse group of chronic autoimmune diseases with varying etiologies, clinical presentations, and prognoses, often demand prolonged pharmacological interventions, creating a pressing need for novel, efficient, and low-risk treatment options. ADCs, with their ability to precisely target the immune components, have emerged as a novel therapeutic strategy in this context. This review will provide an overview of the core components and mechanisms behind ADCs, a summary of the latest clinical trials of ADCs for the treatment of rheumatic diseases, and a discussion of the challenges and future prospects faced by the development of next-generation ADCs. SIGNIFICANCE STATEMENT: There is a lack of efficient and low-risk targeted therapeutics for rheumatic diseases. Antibody-drug conjugates, a class of cutting-edge therapeutic drugs, have emerged as a promising targeted therapeutic strategy for rheumatic disease. Although there is limited literature summarizing the progress of antibody-drug conjugates in the field of rheumatic disease, updating the advancements in this area provides novel insights into the development of novel antirheumatic drugs.

Relative efficacy of antibody-drug conjugates and other anti-HER2 treatments on survival in HER2-positive advanced breast cancer: a systematic review and meta-analysis

BACKGROUND

Novel antibody-drug conjugates (ADCs) drugs present a promising anti-cancer treatment, although survival benefits for HER2-positive advanced breast cancer (BC) remain controversial. The aim of this meta-analysis was to evaluate the comparative effect of ADCs and other anti-HER2 therapy on progression-free survival (PFS) and overall survival (OS) for treatment of HER2-positive locally advanced or metastatic BC.

METHODS

Relevant randomized controlled trials (RCTs) were retrieved from five databases. The risk of bias was assessed with the Cochrane Collaboration's tool for RCTs by RevMan5.4 software. The hazard ratio (HR) and 95% confidence intervals (CIs) were extracted to evaluate the benefit of ADCs on PFS and OS in HER2-positive advanced BC by meta-analysis.

RESULTS

Meta-analysis of six RCTs with 3870 patients revealed that ADCs significantly improved PFS (HR: 0.63, 95% CI: 0.49-0.80, P = 0.0002) and OS (HR: 0.79, 95% CI: 0.72-0.86, P < 0.0001) of patients with HER2-positive locally advanced or metastatic BC. Subgroup analysis showed that PFS and OS were obviously prolonged for patients who previously received HER2-targeted therapy. Sensitivity analysis and publication bias suggested that the results were stable and reliable.

CONCLUSION

Statistically significant benefits for PFS and OS were observed with ADCs in HER2-positive locally advanced or metastatic BC, especially for those who received prior anti-HER2 treatment.

Incidence of antibody-drug conjugate-related fatigue in patients with breast cancer: A systematic review and meta-analysis

BACKGROUND

Numerous studies have reported the efficacy of antibody-drug conjugates (ADCs) for treating breast cancer. However, during cytotoxic drug treatment, long-term disabling fatigue is common. Moreover, studies in the relevant literature have indicated that fatigue can significantly increase the incidence of depression and sleep disorders. Therefore, this meta-analysis aims to evaluate the incidence of fatigue in breast cancer survivors treated with ADCs.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane Library databases were systematically searched for articles and conference abstracts published before March 16, 2023. Further, two authors independently extracted data from the included studies. The primary outcome of this study was the incidence of all-grade fatigue caused by the use of ADCs in patients with breast cancer. Finally, a random-effects model was used to calculate the incidence and 95% confidence intervals (CIs) of the outcome.

RESULTS

Overall, 7963 patients from 31 studies were included in this meta-analysis to assess the incidence of fatigue caused by the use of approved and marketed ADCs in patients with breast cancer. Notably, the incidence of all-grade fatigue during ADC monotherapy was 39.84% (95% CI, 35.09%-44.69%). In subgroup analyses, among ADCs, the incidence of trastuzumab deruxtecan-induced fatigue was the highest, with an all-grade fatigue incidence of 47.05% (95% CI, 42.38%-51.75%). Meanwhile, the incidence of trastuzumab emtansine (T-DM1)-induced all-grade fatigue was 35.17% (95% CI, 28.87%-41.74%), which was the lowest among ADCs. Further, the incidence of all-grade fatigue due to sacituzumab govitecan was 42.82% (95% CI, 34.54%-51.32%), which was higher than that due to T-DM1. Moreover, the incidence of fatigue was higher with T-DM1 combination therapy than with monotherapy.

CONCLUSIONS

Clinicians have highlighted the high incidence of ADC-related fatigue and its negative impact on patients' physical and mental health, making fatigue an important research variable. The results of this study will further contribute to a comprehensive understanding of ADCs, which have some clinical importance and are of great benefit to patients with breast cancer.

What influences the activity of Degrader-Antibody conjugates (DACs)

The targeted protein degradation (TPD) technology employing proteolysis-targeting chimeras (PROTACs) has been widely applied in drug chemistry and chemical biology for the treatment of cancer and other diseases. PROTACs have demonstrated significant advantages in targeting undruggable targets and overcoming drug resistance. However, despite the efficient degradation of targeted proteins achieved by PROTACs, they still face challenges related to selectivity between normal and cancer cells, as well as issues with poor membrane permeability due to their substantial molecular weight. Additionally, the noteworthy toxicity resulting from off-target effects also needs to be addressed. To solve these issues, Degrader-Antibody Conjugates (DACs) have been developed, leveraging the targeting and internalization capabilities of antibodies. In this review, we elucidates the characteristics and distinctions between DACs, and traditional Antibody-drug conjugates (ADCs). Meanwhile, we emphasizes the significance of DACs in facilitating the delivery of PROTACs and delves into the impact of various components on DAC activity. These components include antibody targets, drug-antibody ratio (DAR), linker types, PROTACs targets, PROTACs connections, and E3 ligase ligands. The review also explores the suitability of different targets (antibody targets or PROTACs targets) for DACs, providing insights to guide the design of PROTACs better suited for antibody conjugation.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Analysis of Adverse Events Associated with Trastuzumab Deruxtecan in Patients with Gastric and Breast Cancer: A Retrospective Study

Trastuzumab deruxtecan (T-DXd) has displayed demonstrable efficacy and manageable toxicity in previously treated patients with advanced gastric and breast cancer, and it has been approved in Japan. However, there is a lack of data on the optimal management in clinical practice. Therefore, we assessed the adverse event (AE) profiles of T-DXd in patients with advanced gastric or breast cancer to provide guidance for appropriate management. This retrospective study was conducted at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research. We reviewed the medical records of patients with advanced gastric or breast cancer who received T-DXd between May 2020 and December 2021. AEs occurring within the first three cycles of T-DXd were evaluated according to Common Terminology Criteria for Adverse Events version 5.0. Thirty-six patients were enrolled (gastric: n = 19, breast: n = 17). All 15 males had gastric cancer, whereas 4 and 17 females had gastric and breast cancer, respectively. Interstitial lung disease (ILD) occurred in five patients (14%), but no patients had severe ILD. Gastrointestinal (GI) toxicities, including nausea (61%), vomiting (22%), decreased appetite (33%), and diarrhea (39%), were the most common AEs. The incidence of GI toxicities did not differ by cancer type; however, nausea was significantly more common in females (81 vs. 33%; p < 0.01). T-DXd was safely administered in clinical practice in patients with previously treated advanced gastric or breast cancer. The management of GI toxicities is important in the clinical implementation of T-DXd.

Development of antibody-drug conjugates in cancer: Overview and prospects

In recent years, remarkable breakthroughs have been reported on antibody-drug conjugates (ADCs), with 15 ADCs successfully entering the market over the past decade. This substantial development has positioned ADCs as one of the fastest-growing domains in the realm of anticancer drugs, demonstrating their efficacy in treating a wide array of malignancies. Nonetheless, there is still an unmet clinical need for wider application, better efficacy, and fewer side effects of ADCs. An ADC generally comprises an antibody, a linker and a payload, and the combination has profound effects on drug structure, pharmacokinetic profile and efficacy. Hence, optimization of the key components provides an opportunity to develop ADCs with higher potency and fewer side effects. In this review, we comprehensively reviewed the current development and the prospects of ADC, provided an analysis of marketed ADCs and the ongoing pipelines globally as well as in China, highlighted several ADC platforms and technologies specific to different pharmaceutical enterprises and biotech companies, and also discussed the new related technologies, possibility of next-generation ADCs and the directions of clinical research.

Monoclonal Antibodies and Antibody-drug Conjugates as Emerging Therapeutics for Breast Cancer Treatment

When breast cells divide and multiply out of control, it is called breast cancer. Symptoms include lump formation in the breast, a change in the texture or color of the breast, or a discharge from the nipple. Local or systemic therapy is frequently used to treat breast cancer. Surgical and radiation procedures limited to the affected area are examples of local management. There has been significant worldwide progress in the development of monoclonal antibodies (mAbs) since 1986, when the first therapeutic mAb, Orthoclone OKT3, became commercially available. mAbs can resist the expansion of cancer cells by inducing the destruction of cellular membranes, blocking immune system inhibitors, and preventing the formation of new blood vessels. mAbs can also target growth factor receptors. Understanding the molecular pathways involved in tumor growth and its microenvironment is crucial for developing effective targeted cancer therapeutics. Due to their unique properties, mAbs have a wide range of clinical applications. Antibody-drug conjugates (ADCs) are drugs that improve the therapeutic index by combining an antigen-specific antibody with a payload. This review focuses on the therapeutic applications, mechanistic insights, characteristics, safety aspects, and adverse events of mAbs like trastuzumab, bevacizumab, pertuzumab, ertumaxomab, and atezolizumab in breast cancer treatment. The creation of novel technologies utilizing modified antibodies, such as fragments, conjugates, and multi-specific antibodies, must be a central focus of future studies. This review will help scientists working on developing mAbs to treat cancers more effectively.

Clinical perspective: Antibody-drug conjugates for the treatment of HER2-positive breast cancer

Antibody-drug conjugates (ADCs) are a promising class of cancer biopharmaceuticals that exploit the specificity of a monoclonal antibody (mAb) to selectively deliver highly cytotoxic small molecules to targeted cancer cells, leading to an enhanced therapeutic index through increased antitumor activity and decreased off-target toxicity. ADCs hold great promise for the treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer after the approval and tremendous success of trastuzumab emtansine and trastuzumab deruxtecan, representing a turning point in both HER2-positive breast cancer treatment and ADC technology. Additionally and importantly, a total of 29 ADC candidates are now being investigated in different stages of clinical development for the treatment of HER2-positive breast cancer. The purpose of this review is to provide an insight into the ADC field in cancer treatment and present a comprehensive overview of ADCs approved or under clinical investigation for the treatment of HER2-positive breast cancer.

Discovery of novel antibody-drug conjugates bearing tissue protease specific linker with both anti-angiogenic and strong cytotoxic effects

Bevacizumab is an FDA-approved class of monoclonal antibodies used to inhibit angiogenesis and promote normalization of blood vessels. It is usually combined with chemotherapeutic agents to treat a variety of solid tumors. However, the whole-body toxicities and toxicity associated with chemotherapy greatly limit the clinical use of this combination therapy. Antibody-drug conjugates (ADCs) couple monoclonal antibodies to cytotoxic molecules via a linker, utilizing the high specificity of monoclonal antibodies to tumor surface antigens to act as a "biological missile" to deliver chemotherapeutic drugs to the tumor site. Herein, we designed a bevacizumab-based ADC, Bevacizumab Vedotin, conjugating bevacizumab to the microtubulin inhibitor MMAE via a tissue protease-specific linker. Biological studies showed strong stability and good tumor cell targeting of our constructed ADCs; rapid drug release was achieved in the presence of exogenous histone protease B. In addition, Bevacizumab Vedotin exhibited good anti-proliferative, apoptosis-promoting and cell cycle-stalling effects on glioma (U87), hepatocellular carcinoma (HepG2), and breast cancer (MCF-7) cell lines. Further in vitro assays demonstrated the enhanced anti-migration activity against MCF-7, potent anti-angiogenic effects, and blockade of the VEGF/VEGFR pathway of Bevacizumab Vedotin.

Multicentre, randomised, double-blind, placebo-controlled phase II study of prophylactic olanzapine for patients with metastatic breast cancer receiving T-DXd treatment: protocol for the ERICA study (WJOG14320B)

INTRODUCTION

The antibody-drug conjugate trastuzumab deruxtecan (T-DXd) has led to a change in the clinical management of breast cancer. Nausea and vomiting are the most common adverse events of T-DXd, which cannot be completely alleviated by standard prophylactic regimens. Olanzapine is particularly effective in preventing delayed nausea caused by chemotherapy. In this study, we will evaluate the efficacy of olanzapine in managing persistent nausea and vomiting during T-DXd treatment.

METHODS AND ANALYSIS

The ERICA study is a multicentre, placebo-controlled, double-blind, randomised phase II study with the aim to evaluate the antiemetic effects of the prophylactic olanzapine (5 mg orally, on days 1-6) or placebo combined with a 1,5-hydroxytryptamine-3 (5-HT₃)-receptor antagonist and dexamethasone in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer undergoing T-DXd treatment. For a period of 22 days from the day of T-DXd treatment, patients will document their experience in an electronic symptom diary daily during observational periods. The primary endpoint is the complete response rate, defined as no vomiting and no rescue medications during the 'delayed phase' of 24-120 hours post-T-DXd administration. In addition, we define 120-504 hour as the 'persistent phase' and 0-504 hours as the 'overall phase' for secondary endpoint analysis. We have estimated that a total sample size of at least 156 patients is needed to allow a power of 80% at a one-sided significance level of 20% in this study. The target sample size is set to 166 to account for possible case exclusions.

ETHICS AND DISSEMINATION

The study protocol is approved by the West Japan Oncology Group protocol review committee and the SHOWA University Clinical Research Review Board. The study results will be presented at international conferences and published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

jRCTs031210410.

Chromatin Remodeling Enzyme Cluster Predicts Prognosis and Clinical Benefit of Therapeutic Strategy in Breast Cancer

The treatment provided for breast cancer depends on the expression of hormone receptors, human epidermal growth factor receptor-2 (HER2), and cancer staging. Surgical intervention, along with chemotherapy or radiation therapy, is the mainstay of treatment. Currently, precision medicine has led to personalized treatment using reliable biomarkers for the heterogeneity of breast cancer. Recent studies have shown that epigenetic modifications contribute to tumorigenesis through alterations in the expression of tumor suppressor genes. Our aim was to investigate the role of epigenetic modifications in genes involved in breast cancer. A total of 486 patients from The Cancer Genome Atlas Pan-cancer BRCA project were enrolled in our study. Hierarchical agglomerative clustering analysis further divided the 31 candidate genes into 2 clusters according to the optimal number. Kaplan–Meier plots showed worse progression-free survival (PFS) in the high-risk group of gene cluster 1 (GC1). In addition, the high-risk group showed worse PFS in GC1 with lymph node invasion, which also presented a trend of better PFS when chemotherapy was combined with radiotherapy than when chemotherapy was administered alone. In conclusion, we developed a novel panel using hierarchical clustering that high-risk groups of GC1 may be promising predictive biomarkers in the clinical treatment of patients with breast cancer.

Degrader-Antibody Conjugates: Emerging New Modality

In order to deliver chemotherapeutics more efficiently, small-molecule-drug conjugates (SMDCs) and antibody-drug conjugates (ADCs) have been synthesized and explored. These conjugates not only provide selective delivery but also improve the therapeutic index of toxins. By merging this conjugate concept with target protein degradation (TPD), the degrader-antibody conjugate (DAC) field has emerged, and clinical trials have even begun in recent years. In this Perspective, we provide the concepts, applications, and recent advances in the area of DACs.

Innovative Therapeutic Approaches for Patients with HER2-Positive Breast Cancer

Overexpression of human epidermal growth factor receptor 2 (HER2), a transmembrane tyrosine kinase receptor, has been described in about 15-20% of breast cancer (BC) and is associated with poor outcomes. Trastuzumab is the first anti-HER2 monoclonal antibody (mAB) that blocks receptor activity but it also activates immune response against cancer cells, thus, revolutionizing the prognosis of patients with HER2-positive BC. Over the years, new therapies have been developed, including other mAbs and tyrosine kinase inhibitors (TKIs) that required multimodal approaches with chemotherapy to optimize their anticancer activity. This chapter gives a comprehensive overview of the last advancements including new approaches and future combinations, which seem to be very promising in overcoming resistance to the traditional anti-HER2 treatments. A modern therapeutic algorithm should include treatment options based on tumour patterns and a patient-centred approach. A proper patient's selection is crucial to derive maximal benefits from a treatment strategy and emerging biomarkers should be integrated along with the HER2 status, which is currently the only validated biomarker in the context of HER2-positive disease. These biomarkers might include molecular features with reported prognostic/predictive significance, such as phosphatidylinositol 3' -kinase (PI3K) or mitogen-activated protein kinase (MAPK) pathways, programmed cell death protein ligand 1 (PD-L1), and tumour-infiltrating lymphocytes (TILs), which all affect prognosis and response to treatments.

Preclinical profiles of SKB264, a novel anti-TROP2 antibody conjugated to topoisomerase inhibitor, demonstrated promising antitumor efficacy compared to IMMU-132

Purpose

The aim of this study was to improve the intratumoral accumulation of an antibody-drug conjugate (ADC) and minimize its off-target toxicity, SKB264, a novel anti-trophoblast antigen 2 (TROP2) ADC that was developed using 2-methylsulfonyl pyrimidine as the linker to conjugate its payload (KL610023), a belotecan-derivative topoisomerase I inhibitor. The preclinical pharmacologic profiles of SKB264 were assessed in this study.

Methods

The in vitro and in vivo pharmacologic profiles of SKB264, including efficacy, pharmacokinetics-pharmacodynamics (PK-PD), safety, and tissue distribution, were investigated using TROP2-positive cell lines, cell-derived xenograft (CDX), patient-derived xenograft (PDX) models, and cynomolgus monkeys. Moreover, some profiles were compared with IMMU-132.

Results

In vitro, SKB264 and SKB264 monoclonal antibody (mAb) had similar internalization abilities and binding affinities to TROP2. After cellular internalization, KL610023 was released and inhibited tumor cell survival. In vivo, SKB264 significantly inhibited tumor growth in a dose-dependent manner in both CDX and PDX models. After SKB264 administration, the serum or plasma concentration/exposure of SKB264 (conjugated ADC, number of payload units ≥1), total antibody (Tab, unconjugated and conjugated mAb regardless of the number of the payload units), and KL610023 in cynomolgus monkeys increased proportionally with increasing dosage from 1 to 10 mg/kg. The linker stability of SKB264 was significantly enhanced as shown by prolonged payload half-life in vivo (SKB264 vs. IMMU-132, 56.3 h vs. 15.5 h). At the same dose, SKB264's exposure in tumor tissue was 4.6-fold higher than that of IMMU-132.

Conclusions

Compared with IMMU-132, the longer half-life of SKB264 had a stronger targeting effect and better antitumor activity, suggesting the better therapeutic potential of SKB264 for treating TROP2-positive tumors.

Unveiling the antibody-drug conjugates portfolio in battling Triple-negative breast cancer: Therapeutic trends and Future horizon

Triple-negative breast cancer (TNBC) showcases a labyrinthine network exhibiting deficient expression of Estrogen receptor (ER), Progesterone receptor (PR), and Human-epidermal growth factor receptor-2 (HER2). This restricts the conventional chemotherapeutic, hormonal, and few targeted regimens in showing efficient anti-tumor response. Antibody-drug conjugates (ADCs) are target-specific conjugates comprising a monoclonal antibody attached to the desired cytotoxic payload with the support of a stable linker. They are designated as one of the encouraging sets of targeted therapies that have unveiled affirmative outcomes owing to increased specificity in targeting the undetectable or deficiently expressed targets. Another virtue of ADCs lending superiority to this approach is the presence of inherent bystander effect which has a detrimental influence on the tumor microenvironment (TME) devoid of antigen expression. In the current scenario, FDA-approved Sacituzumab govitecan is widely being utilized to mitigate TNBC while many other ADCs are being studied in clinical trials. Additionally, a focus has been set on revelation of application of Trastuzumab deruxtecan in HER2-low metastatic breast cancer which widens the current therapeutic horizon dealing with such carcinomas. After making an effort towards sketching ADCs profile, we conclude that this novel approach deserves to be investigated through future campaigns owing to its remarkable bystander effect, ability to precisely recognize the antigen and spare the naïve cells from detrimental toxicity. Exploration of the remarkable potential of Sacituzumab govitecan in multiple indications including TNBC portrays the prominence of ADCs and prompts the bright future of this therapeutic approach. In this review, we present the basic foundation of ADCs alongside summarizing the building blocks of several ADCs used in TNBC. Furthermore, by shedding light on the therapeutic regimens and concomitant effects of various ADCs derived from the supportive backbone of clinical trials, we have attempted to convene several segments of ADCs and portray their potentialities time ahead.

Peptide-Based Bioconjugates and Therapeutics for Targeted Anticancer Therapy

With rapidly growing knowledge in bioinformatics related to peptides and proteins, amino acid-based drug-design strategies have recently gained importance in pharmaceutics. In the past, peptide-based biomedicines were not widely used due to the associated severe physiological problems, such as low selectivity and rapid degradation in biological systems. However, various interesting peptide-based therapeutics combined with drug-delivery systems have recently emerged. Many of these candidates have been developed for anticancer therapy that requires precisely targeted effects and low toxicity. These research trends have become more diverse and complex owing to nanomedicine and antibody–drug conjugates (ADC), showing excellent therapeutic efficacy. Various newly developed peptide–drug conjugates (PDC), peptide-based nanoparticles, and prodrugs could represent a promising therapeutic strategy for patients. In this review, we provide valuable insights into rational drug design and development for future pharmaceutics.

A supramolecular nanofiber formed by enzyme-instructed self-assembly for SKBR-3 cell selective inhibition

Cell-targeted peptides are recommended for precision cancer treatment due to their comparable targeting properties, small molecular size and good biocompatibility. However, unpredictable bioactivity, low penetration rate and poor stability greatly limit its efficacy. Supramolecular self-assembly based on synthetic peptide has great potential to solve related problems and achieve better therapeutic effects. Herein, we report and compare the effects of two different assembly pathway, heating-cooling and enzyme instruction, on the penetrability of SKBR-3 cell targeted peptides. It was found that enzyme-instructed self-assembly (EISA) resulted in hydrogels composed of uniform supramolecular nanofibers, whereas heating-cooling resulted in solutions and precipitations composed of slightly different nanoparticles. The nanofibers formed by EISA showed enhanced cellular uptake (2.54 μM), which was significantly higher than the 1.06 μM of the nanoparticles formed by temperature regulation. Thus, EISA is a promising strategy to improve the cell penetration rate of targeted peptides, and could provide a better solution for precision cancer treatment.

Antibody-drug conjugate as targeted therapeutics against hepatocellular carcinoma: preclinical studies and clinical relevance

An antibody-drug conjugate (ADC) is an advanced chemotherapeutic option with immense promises in treating many tumor. They are designed to selectively attack and kill neoplastic cells with minimal toxicity to normal tissues. ADCs are complex engineered immunoconjugates that comprise a monoclonal antibody for site-directed delivery and cytotoxic payload for targeted destruction of malignant cells. Therefore, it enables the reduction of off-target toxicities and enhances the therapeutic index of the drug. Hepatocellular carcinoma (HCC) is a solid tumor that shows high heterogeneity of molecular phenotypes and is considered the second most common cause of cancer-related death. Studies show enormous potential for ADCs targeting GPC3 and CD24 and other tumor-associated antigens in HCC with their high, selective expression and show potential outputs in preclinical evaluations. The review mainly highlights the preclinical evaluation of different antigen-targeted ADCs such as MetFab-DOX, Anti-c-Met IgG-OXA, Anti CD 24, ANC-HN-01, G7mab-DOX, hYP7-DCand hYP7-PC, Anti-CD147 ILs-DOX and AC133-vcMMAF against hepatocellular carcinoma and its future relevance.

Antibody-Drug Conjugate Targets, Drugs and Linkers

Antibody-drug conjugates offer the possibility of directing powerful cytotoxic agents to a malignant tumor while sparing normal tissue. The challenge is to select an antibody target expressed exclusively or at highly elevated levels on the surface of tumor cells and either not all or at low levels on normal cells. The current review explores 78 targets that have been explored as antibody-drug conjugate targets. Some of these targets have been abandoned, 9 or more are the targets of FDA-approved drugs, and most remain active clinical interest. Antibody-drug conjugates require potent cytotoxic drug payloads, several of these small molecules are discussed, as are the linkers between the protein component and small molecule components of the conjugates. Finally, conclusions regarding the elements for the successful antibody-drug conjugate are discussed.

Linkers: An Assurance for Controlled Delivery of Antibody-Drug Conjugate

As one of the major therapeutic options for cancer treatment, chemotherapy has limited selectivity against cancer cells. Consequently, this therapeutic strategy offers a small therapeutic window with potentially high toxicity and thus limited efficacy of doses that can be tolerated by patients. Antibody-drug conjugates (ADCs) are an emerging class of anti-cancer therapeutic drugs that can deliver highly cytotoxic molecules directly to cancer cells. To date, twelve ADCs have received market approval, with several others in clinical stages. ADCs have become a powerful class of therapeutic agents in oncology and hematology. ADCs consist of recombinant monoclonal antibodies that are covalently bound to cytotoxic chemicals via synthetic linkers. The linker has a key role in ADC outcomes because its characteristics substantially impact the therapeutic index efficacy and pharmacokinetics of these drugs. Stable linkers and ADCs can maintain antibody concentration in blood circulation, and they do not release the cytotoxic drug before it reaches its target, thus resulting in minimum off-target effects. The linkers used in ADC development can be classified as cleavable and non-cleavable. The former, in turn, can be grouped into three types: hydrazone, disulfide, or peptide linkers. In this review, we highlight the various linkers used in ADC development and their design strategy, release mechanisms, and future perspectives.

Novel development strategies and challenges for anti-Her2 antibody-drug conjugates

Antibody-drug conjugates (ADCs) combining potent cytotoxicity of small-molecule drugs with the selectivity and excellent pharmacokinetic profile of monoclonal antibody (mAb) are promising therapeutic modalities for a diverse range of cancers. Owing to overexpression in a wide range of tumors, human epidermal growth factor receptor 2 (Her2) is one of the most utilized targeting antigens for ADCs to treat Her2-positive cancers. Owing to the high density of Her2 antigens on the tumor cells and high affinity and high internalization capacity of corresponding antibodies, 56 anti-Her2 ADCs which applied >10 different types of novel payloads had entered preclinical or clinical trials. Seven of 12 Food and Drug Administration (FDA)-approved ADCs including Polivy (2019), Padcev (2019), EnHertu (2019), Trodelvy (2020), Blenrep (2020), Zynlonta (2021), and Tivdak) (2021) have been approved by FDA in the past three years alone, indicating that the maturing of ADC technology brings more productive clinical outcomes. This review, focusing on the anti-Her2 ADCs in clinical trials or on the market, discusses the strategies to select antibody formats, the linkages between linker and mAb, and effective payloads with particular release and action mechanisms for a good clinical outcome.

Effective Cancer Subtype and Stage Prediction via Dropfeature-DNNs

Precise cancer subtype and/or stage prediction is instrumental for cancer diagnosis, treatment and management. However, most of the existing methods based on genomic profiles suffer from issues such as overfitting, high computational complexity and selected features (i.e., genes) not directly related to forecast precision. These deficiencies are largely due to the nature of "high dimensionality and small sample size" inherent in molecular data, and such a nature is often deemed as an obstacle to the application of deep learning, e.g., deep neural networks (DNNs), to biomedicine and cancer research. In this paper, we propose a DNN-based algorithm coupled with a new embedded feature selection technique, named Dropfeature-DNNs, to address these issues. Dropfeature-DNNs can discard some irrelevant features (i.e., genes) when training DNNs, and we formulate Dropfeature-DNNs as an iterative AUC optimization problem. As such, an "optimal" feature subset that contains meaningful genes for accurate tumor subtype and/or stage prediction can be obtained when the AUC optimization converges in the training stage. Since the feature subset and AUC optimizations are synchronous with the training phase of DNNs, model complexity and computational cost are simultaneously reduced. Rigorous feature subset convergence analysis and error bound inference provide a solid theoretical foundation for the proposed method. Extensive empirical comparisons to benchmark methods further demonstrate the efficacy of Dropfeature-DNNs in cancer subtype and/or stage prediction using HDSS gene expression data from multiple cancer types.

Current understandings and clinical translation of nanomedicines for breast cancer therapy

Breast cancer is one of the most frequently diagnosed cancers that is threatening women's life. Current clinical treatment regimens for breast cancer often involve neoadjuvant and adjuvant systemic therapies, which somewhat are associated with unfavorable features. Also, the heterogeneous nature of breast cancers requires precision medicine that cannot be fulfilled by a single type of systemically administered drug. Taking advantage of the nanocarriers, nanomedicines emerge as promising therapeutic agents for breast cancer that could resolve the defects of drugs and achieve precise drug delivery to almost all sites of primary and metastatic breast tumors (e.g. tumor vasculature, tumor stroma components, breast cancer cells, and some immune cells). Seven nanomedicines as represented by Doxil® have been approved for breast cancer clinical treatment so far. More nanomedicines including both non-targeting and active targeting nanomedicines are being evaluated in the clinical trials. However, we have to realize that the translation of nanomedicines, particularly the active targeting nanomedicines is not as successful as people have expected. This review provides a comprehensive landscape of the nanomedicines for breast cancer treatment, from laboratory investigations to clinical applications. We also highlight the key advances in the understanding of the biological fate and the targeting strategies of breast cancer nanomedicine and the implications to clinical translation.

Engineered Bifunctional Proteins for Targeted Cancer Therapy: Prospects and Challenges

Bifunctional proteins (BFPs) are a class of therapeutic agents produced through genetic engineering and protein engineering, and are increasingly used to treat various human diseases, including cancer. These proteins usually have two or more biological functions-specifically recognizing different molecular targets to regulate the related signaling pathways, or mediating effector molecules/cells to kill tumor cells. Unlike conventional small-molecule or single-target drugs, BFPs possess stronger biological activity but lower systemic toxicity. Hence, BFPs are considered to offer many benefits for the treatment of heterogeneous tumors. In this review, the authors briefly describe the unique structural feature of BFP molecules and innovatively divide them into bispecific antibodies, cytokine-based BFPs (immunocytokines), and protein toxin-based BFPs (immunotoxins) according to their mode of action. In addition, the latest advances in the development of BFPs are discussed and the potential limitations or problems in clinical applications are outlined. Taken together, future studies need to be centered on understanding the characteristics of BFPs for optimizing and designing more effective such drugs.

A Novel Prognostic Signature of Immune-Related Long Noncoding RNA Pairs for Tumor-Infiltrating Immune Cells and Drug Susceptibility in Breast Cancer

Prognostic signatures of specific immune-related long noncoding RNAs (irlncRNAs) have been elucidated with the development of immunotherapy for breast cancer, but the heterogeneity of gene expression in different patients still limits their effectiveness. We constructed a new prognostic signature based on the relative expression of differentially expressed irlncRNA (DEirlncRNA) pairs and analyzed its clinical application in 1069 patients from The Cancer Genome Atlas-Breast Cancer (TCGA-BRCA) containing 745 White patients, 180 Black and African American patients, 58 Asian patients, 181 stage I patients, 606 stage II patients, 240 stage III patients, and 20 stage IV patients. Data from TCGA-BRCA and ImmPort were used to screen DEirlncRNAs, and the DEirlncRNA pairs were established by cyclical single comparison of each DEirlncRNA. After the data optimization, we constructed a signature containing 24 DEirlncRNA pairs. Risk groups of this signature were defined using the cutoff value from the 10-year survival receiver operating characteristic curve, and Kaplan-Meier analysis verified its prognostic effectiveness. Furthermore, we confirmed this signature as an independent prognostic factor and confirmed its close association with traditional clinicopathological factors. Moreover, this risk signature was closely related to tumor-infiltrating immune cells and drug susceptibility. In short, we successfully constructed a risk signature of DEirlncRNA pairs, which might provide new insights for breast cancer precision therapy.

Multiple strategies for the treatment of invasive breast carcinoma: A comprehensive prospective

In this review, we emphasize on evolving therapeutic strategies and advances in the treatment of breast cancer (BC). This includes small-molecule inhibitors under preclinical and clinical investigation, phytoconstituents with antiproliferative potential, targeted therapies as antibodies and antibody-drug conjugates (ADCs), vaccines as immunotherapeutic agents and peptides as a novel approach inhibiting the interaction of oncogenic proteins. We provide an update of molecules under different phases of clinical investigation which aid in the identification of loopholes or shortcomings that can be overcomed with future breast cancer research.

Breast Cancer Treatments: Updates and New Challenges

Breast cancer (BC) is the most frequent cancer diagnosed in women worldwide. This heterogeneous disease can be classified into four molecular subtypes (luminal A, luminal B, HER2 and triple-negative breast cancer (TNBC)) according to the expression of the estrogen receptor (ER) and the progesterone receptor (PR), and the overexpression of the human epidermal growth factor receptor 2 (HER2). Current BC treatments target these receptors (endocrine and anti-HER2 therapies) as a personalized treatment. Along with chemotherapy and radiotherapy, these therapies can have severe adverse effects and patients can develop resistance to these agents. Moreover, TNBC do not have standardized treatments. Hence, a deeper understanding of the development of new treatments that are more specific and effective in treating each BC subgroup is key. New approaches have recently emerged such as immunotherapy, conjugated antibodies, and targeting other metabolic pathways. This review summarizes current BC treatments and explores the new treatment strategies from a personalized therapy perspective and the resulting challenges.

Sacituzumab govitecan and trastuzumab deruxtecan: two new antibody-drug conjugates in the breast cancer treatment landscape

BACKGROUND

Two new antibody-drug conjugates (ADCs) containing a topoisomerase I inhibitor payload have recently emerged in the breast cancer (BC) treatment landscape. Sacituzumab govitecan-hziy (SG) is a first-in-class anti-trophoblast cell-surface antigen 2 ADC approved for pretreated metastatic triple-negative breast cancer (mTNBC) and trastuzumab deruxtecan (T-DXd) gained approval for human epidermal growth factor receptor-2 (HER2)-positive advanced BC (aBC). We aim to provide a contemporary review and the current clinical trial landscape of SG and T-DXd in BC.

MATERIALS AND METHODS

We conducted a literature search from Medline database through PubMed, major conference proceedings [abstracts from European Society for Medical Oncology (Breast) Congress, American Society of Clinical Oncology annual meeting, San Antonio Breast Cancer Symposium] and ClinicalTrials.gov with search terms 'sacituzumab govitecan', 'IMMU-132', 'trastuzumab deruxtecan' and 'DS-8201a' up to 21 March 2021.

RESULTS

We assessed 293 records for eligibility, of which 153 were included in this review after screening and exclusion. For SG, efficacy and safety data are available from a phase III trial in pretreated mTNBC and from a phase I/II basket study in mTNBC and hormone receptor-positive/HER2-negative aBC. Thirteen trials with pending primary analysis are ongoing with SG as single agent or in combination, of which 11 are enrolling (2/11 in the early setting). For T-DXd, efficacy/safety data are available as single agent in pretreated HER2-positive (phase Ib and phase II) and in HER2-low aBC (phase Ib), and in combination with nivolumab in HER2-low/positive aBC (phase Ib). Of 23 ongoing trials with T-DXd, 12 are open for enrollment and 3 phase III trials have completed recruitment. The distinct safety profiles of both drugs and their management are discussed.

CONCLUSION

Given their robust single-agent activity, SG and T-DXd are expected to substantially impact treatment standards, both in and far beyond the currently approved indications. Several trials are investigating new treatment settings for both drugs, including a transition to earlier lines and combinations with other anticancer treatments such as immune checkpoint inhibitors.

Importance and Considerations of Antibody Engineering in Antibody-Drug Conjugates Development from a Clinical Pharmacologist's Perspective

Antibody-drug conjugates (ADCs) appear to be in a developmental boom, with five FDA approvals in the last two years and a projected market value of over $4 billion by 2024. Major advancements in the engineering of these novel cytotoxic drug carriers have provided a few early success stories. Although the use of these immunoconjugate agents are still in their infancy, valuable lessons in the engineering of these agents have been learned from both preclinical and clinical failures. It is essential to appreciate how the various mechanisms used to engineer changes in ADCs can alter the complex pharmacology of these agents and allow the ADCs to navigate the modern-day therapeutic challenges within oncology. This review provides a global overview of ADC characteristics which can be engineered to alter the interaction with the immune system, pharmacokinetic and pharmacodynamic profiles, and therapeutic index of ADCs. In addition, this review will highlight some of the engineering approaches being explored in the creation of the next generation of ADCs.

Immunoconjugates for Cancer Targeting: A Review of Antibody-Drug Conjugates and Antibody-Functionalized Nanoparticles

Targeted therapy has been recently highlighted due to the reduction of side effects and improvement in overall efficacy and survival from different types of cancers. Considering the approval of many monoclonal antibodies in the last twenty years, cancer treatment can be accomplished by the combination of monoclonal antibodies and small molecule chemotherapeutics. Thus, strategies to combine both drugs in a single administration system are relevant in the clinic. In this context, two strategies are possible and will be further discussed in this review: antibody-drug conjugates (ADCs) and antibody-functionalized nanoparticles. First, it is important to better understand the possible molecular targets for cancer therapy, addressing different antigens that can selectively bind to antibodies. After selecting the best target, ADCs can be prepared by attaching a cytotoxic drug to an antibody able to target a cancer cell antigen. Briefly, an ADC will be formed by a monoclonal antibody (MAb), a cytotoxic molecule (cytotoxin) and a chemical linker. Usually, surface-exposed lysine or the thiol group of cysteine residues are used as anchor sites for linker-drug molecules. Another strategy that should be considered is antibody-functionalized nanoparticles. Basically, liposomes, polymeric and inorganic nanoparticles can be attached to specific antibodies for targeted therapy. Different conjugation strategies can be used, but nanoparticles coupling between maleimide and thiolated antibodies or activation with the addition of ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/ N-hydroxysuccinimide (NHS) (1:5) and further addition of the antibody are some of the most used strategies. Herein, molecular targets and conjugation strategies will be presented and discussed to better understand the in vitro and in vivo applications presented. Also, the clinical development of ADCs and antibody-conjugated nanoparticles are addressed in the clinical development section. Finally, due to the innovation related to the targeted therapy, it is convenient to analyze the impact on patenting and technology. Information related to the temporal evolution of the number of patents, distribution of patent holders and also the number of patents related to cancer types are presented and discussed. Thus, our aim is to provide an overview of the recent developments in immunoconjugates for cancer targeting and highlight the most important aspects for clinical relevance and innovation.

New Therapeutic Strategies in Advanced Nonoperable or Metastatic HER2-positive Breast Cancer

Despite therapeutic gains in the treatment of HER2-positive (HER2: human epidermal growth factor receptor 2) advanced/metastatic breast cancer, there remains an urgent need for more effective treatment options. At present, there is no definitive approved standard therapy beyond second-line treatment. One of the major challenges is overcoming treatment resistance. Depending on the underlying resistance mechanism, different strategies are being pursued for new innovative treatment concepts in HER2-positive breast cancer. Specifically designed antibodies for targeted therapy are one important focus to successfully meet these challenges. Trastuzumab deruxtecan (T-DXd, DS-8201a), an optimised antibody drug conjugate (ADC) is in clinical trials, showing promising outcomes in patients with advanced, nonoperable or metastatic HER2-positive breast cancer who had already undergone intensive prior treatment. Based on this data, T-DXd has already been approved in the US and Japan for HER2-positive advanced nonoperable and metastatic breast cancer - in the US after at least two prior anti-HER2 targeted treatment lines and in Japan after prior chemotherapy. T-DXd represents successful "antibody engineering". Since the beginning of the year, T-DXd has also been approved in Europe as monotherapy for inoperable or metastatic HER2-positive breast cancer in patients who are pretreated with at least two anti-HER2 directed therapies. This paper presents strategies for improving treatment options in advanced nonoperable and metastatic HER2-positive breast cancer, with the development of T-DXd as an example.

MRP1-targeted near infrared photoimmunotherapy for drug resistant small cell lung cancer

Small cell lung cancer (SCLC), one of the most aggressive cancers, has a high mortality rate and poor prognosis, and the clinical therapeutic outcomes of multidrug resistant SCLC are even worse. Multidrug resistance protein 1 (MRP1), one of the ATP-binding cassette (ABC) transporter proteins that cause decreased drug accumulation in cancer cells, is overexpressed in drug resistant SCLC cells and could be a promising target for treating the patients suffering from this illness. Near infrared photoimmunotherapy (NIR-PIT) is a newly developed approach for targeted cancer treatment which uses a conjugate of a monoclonal antibody and photoabosorber IR700 followed by NIR light irradiation to induce rapid cancer cell death. In the present study, an anti-MRP1 antibody (Mab) -IR700 conjugate (Mab-IR700) was synthesized, purified and used to treat chemoresistant SCLC H69AR cells that overexpressed MRP1, while non-MRP1-expressing H69 cells were used as a control. Then, the photokilling and tumor suppression effect were separately evaluated in H69AR cells both in vitro and in vivo. Higher cellular delivery of Mab-IR700 was detected in H69AR cells, whereas there was little uptake of IgG-IR700 in both H69 and H69AR cells. Due to the targeting activity of Mab, stronger photokilling effect was found both in H69AR cells and spheroids treated with Mab-IR700, while superior tumor suppression effect was also observed in the mice treated with Mab-IR700 and light illumination. Photoacoustic imaging results proved that oxygen was involved in NIR-PIT treatment, and TUNEL staining images showed the occurrence of cell apoptosis, which was also testified by HE staining. This research provides MRP1 as a novel target for PIT and presents a prospective way for treating drug resistant SCLC and, thus, should be further studied.

Current Treatment Approaches for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer in Adjuvant and Neoadjuvant Settings

Breast cancer (BC) is the second most common cancer and the second leading cause of mortality among women globally. Approximately 20 to 25% of BC patients have amplification of the human epidermal growth factor receptor 2 (HER2) genes, a marker of poor prognosis. However, the introduction of anti-HER2-therapies (trastuzumab, followed closely by lapatinib, pertuzumab, trastuzumab emtansine, and neratinib) has changed the natural history of HER2-positive BC and improved the outcome in HER2-positive BC patients. The preeminence of anti-HER2 combination therapy in achieving complete inhibition of the various HER receptor dimers has been demonstrated in clinical studies. However, despite these therapeutic advances, tumors expressing estrogen receptor have poorer responses to targeted therapy and are more likely to relapse. A better understanding of resistance to existing anti-HER2 agents, along with the role played by the microenvironment and of interconnected signaling pathways, can permit tailor-made therapeutic options for each patient. This review aimed to evaluate treatment approaches for BC patients with HER2-positive disease in the adjuvant and neoadjuvant settings, also exploring the possibilities of extended duration of anti-HER2 maintenance therapy.

Extracellular Matrix: Emerging Roles and Potential Therapeutic Targets for Breast Cancer

Increasing evidence shows that the extracellular matrix (ECM) is an important regulator of breast cancer (BC). The ECM comprises of highly variable and dynamic components. Compared with normal breast tissue under homeostasis, the ECM undergoes many changes in composition and organization during BC progression. Induced ECM proteins, including fibrinogen, fibronectin, hyaluronic acid, and matricellular proteins, have been identified as important components of BC metastatic cells in recent years. These proteins play major roles in BC progression, invasion, and metastasis. Importantly, several specific ECM molecules, receptors, and remodeling enzymes are involved in promoting resistance to therapeutic intervention. Additional analysis of these ECM proteins and their downstream signaling pathways may reveal promising therapeutic targets against BC. These potential drug targets may be combined with new nanoparticle technologies. This review summarizes recent advances in functional nanoparticles that target the ECM to treat BC. Accurate nanomaterials may offer a new approach to BC treatment.

Trastuzumab deruxtecan in HER2-positive metastatic breast cancer and beyond

INTRODUCTION

Despite the substantial improvements made in human epidermal growth factor receptor 2 (HER2)-targeted therapies since the approval of trastuzumab more than 20 years ago, there is still considerable unmet need in patients with HER2-expressing breast cancer (BC) and other solid tumors. Trastuzumab deruxtecan (T-DXd) is a newer antibody-drug conjugate approved for the treatment of metastatic breast cancer (BC) and gastric cancer (GC) and is under active investigation in other solid tumors, including non-small cell lung cancer, colorectal cancer, and HER2-low tumors.

AREAS COVERED

The current treatment and investigational landscape of HER2-positive and HER2-low metastatic BC (mBC) and the preclinical and clinical trials investigating T-DXd. To identify relevant literature, a search was performed on English-language publications and congress abstracts.

EXPERT OPINION

T-DXd is likely to become the standard of care for second-line treatment of HER2-positive mBC, and it may play a role in the treatment of hormone receptor-positive and triple-negative mBC with HER2-low expression. Because it was recently approved in the United States and Japan to treat HER2-positive metastatic GC, it holds promise for the treatment of other HER2-positive solid tumors, including colorectal cancer, non-small cell lung cancer, and HER2-low BC.

Innovative Bioconjugation Technology for Antibody-Drug Conjugates: Proof of Concept in a CD30-Positive Lymphoma Mouse Model

To overcome stability and heterogeneity issues of antibody-drug conjugates (ADCs) produced with existing bioconjugation technologies incorporating a maleimide motif, we developed McSAF Inside, a new technology based on a trifunctionalized di(bromomethyl)pyridine scaffold. Our solution allows the conjugation of a linker-payload to previously reduced interchain cysteines of a native antibody, resulting in disulfide rebridging. This leads to highly stable and homogeneous ADCs with control over the drug-to-antibody ratio (DAR) and the linker-payload position. Using our technology, we synthesized an ADC, MF-BTX-MMAE, built from anti-CD30 antibody cAC10 (brentuximab), and compared it to Adcetris, the first line treatment against CD30-positive lymphoma, in a CD30-positive lymphoma model. MF-BTX-MMAE displayed improved DAR homogeneity, with a solid batch-to-batch reproducibility, as well as enhanced stability in thermal stress conditions or in the presence of a free thiol-containing protein, such as human serum albumin (HSA). MF-BTX-MMAE showed antigen-binding, in vitro cytotoxicity, in vivo efficacy, and tolerability similar to Adcetris. Therefore, in accordance with current regulatory expectations for the development of new ADCs, McSAF Inside technology gives access to relevant ADCs with improved characteristics and stability.

Recent progress in immunotherapy of breast cancer targeting the human epidermal growth factor receptor 2 (HER2)

OBJECTIVE

Breast cancer is responsible for most of the cancer-induced deaths in women around the world. The current review will discuss different approaches of targeting HER2, an epidermal growth factor overexpressed in 30% of breast cancer cases.

DATA SOURCES

We conducted a search on Pubmed and Scopus databases to find studies relevant to HER2+ breast cancers and targeting HER2 as means of immunotherapy. Out of 1043 articles, 105 studies were included in this review.

DATA SUMMARY

As well as the introduction of HER2 and breast cancer subtypes, we discussed various aspects of HER2-targeting immunotherapy including monoclonal antibodies, Antibody-drug conjugates (ADCs), Chimeric Antigen Receptor (CAR) T-cells and vaccines.

CONCLUSIONS

Despite several ways of controlling breast cancer, the need to investigate new drugs and approaches seems to be much significant as this cancer still has a heavy burden on people's health and survival.

Peptide-Drug Conjugates with Different Linkers for Cancer Therapy

Drug conjugates are chemotherapeutic or cytotoxic agents covalently linked to targeting ligands such as an antibody or a peptide via a linker. While antibody-drug conjugates (ADCs) are now clinically established for cancer therapy, peptide-drug conjugates (PDCs) are gaining recognition as a new modality for targeted drug delivery with improved efficacy and reduced side effects for cancer treatment. The linker in a drug conjugate plays a key role in the circulation time of the conjugate and release of the drug for full activity at the target site. Herein, we highlight the main linker chemistries utilized in the design of PDCs and discuss representative examples of PDCs with different linker chemistries with the related outcome in cell and animal studies.

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.

Advances in EGFR/HER2-directed clinical research on breast cancer

The discovery of the HER2 molecules has embarked a series of investigations on the efficacy and safety of different types of anti-HER2 therapies for treating breast cancer, with the clinical pathway requiring a more detailed, more precise, and more dynamics therapeutic approaches due to the heterogeneity of the disease. As the "do more" and "do less" approaches are becoming more important to personalize treatment for early HER2-positive breast cancer, recent advances aim at tackling the advanced stage of the disease by using novel therapeutic agents and combination strategies. There are also important points of consideration on prognosis and choice of therapies, including HER2 gene copy number, HER2 heterogeneity, tissue biomarkers, blood-based biomarkers, and HER2 mutation and its treatment. Altogether, these could potentially play a vital role in the journey of HER2-positive breast cancer patient to achieve greater survival benefit and potentially a cure for the disease.

Antibody interface prediction with 3D Zernike descriptors and SVM

MOTIVATION

Antibodies are a class of proteins capable of specifically recognizing and binding to a virtually infinite number of antigens. This binding malleability makes them the most valuable category of biopharmaceuticals for both diagnostic and therapeutic applications. The correct identification of the antigen-binding residues in the antibody is crucial for all antibody design and engineering techniques and could also help to understand the complex antigen binding mechanisms. However, the antibody-binding interface prediction field appears to be still rather underdeveloped.

RESULTS

We present a novel method for antibody interface prediction from their experimentally solved structures based on 3D Zernike Descriptors. Roto-translationally invariant descriptors are computed from circular patches of the antibody surface enriched with a chosen subset of physico-chemical properties from the AAindex1 amino acid index set, and are used as samples for a binary classification problem. An SVM classifier is used to distinguish interface surface patches from non-interface ones. The proposed method was shown to outperform other antigen-binding interface prediction software.

AVAILABILITY AND IMPLEMENTATION

Linux binaries and Python scripts are available at https://github.com/sebastiandaberdaku/AntibodyInterfacePrediction. The datasets generated and/or analyzed during the current study are available at https://doi.org/10.6084/m9.figshare.5442229.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Application of magnetic nanoparticles in nucleic acid detection

Nucleic acid is the main material for storing, copying, and transmitting genetic information. Gene sequencing is of great significance in DNA damage research, gene therapy, mutation analysis, bacterial infection, drug development, and clinical diagnosis. Gene detection has a wide range of applications, such as environmental, biomedical, pharmaceutical, agriculture and forensic medicine to name a few. Compared with Sanger sequencing, high-throughput sequencing technology has the advantages of larger output, high resolution, and low cost which greatly promotes the application of sequencing technology in life science research. Magnetic nanoparticles, as an important part of nanomaterials, have been widely used in various applications because of their good dispersion, high surface area, low cost, easy separation in buffer systems and signal detection. Based on the above, the application of magnetic nanoparticles in nucleic acid detection was reviewed.

TROPiCS-02: A Phase III study investigating sacituzumab govitecan in the treatment of HR+/HER2- metastatic breast cancer

Patients with HR+/HER2- metastatic breast cancer (MBC) whose cancers have progressed despite conventional therapies represent an unmet clinical need. Trop-2, a transmembrane calcium signal transducer, is highly expressed in MBC and plays a role in tumor growth and progression. Sacituzumab govitecan (SG) is a novel antibody-drug conjugate comprising an Trop-2 antibody coupled to SN-38, the active metabolite of irinotecan, via a unique hydrolyzable linker. SG has demonstrated promising activity in a Phase I/II IMMU-132-01 basket study in heavily pretreated solid tumors, including HR+/HER2- MBC. We describe the registrational Phase III TROPiCS-02 study (NCT03901339), evaluating SG versus treatment of physician's choice in HR+/HER2- MBC. Trial registration number: NCT03901339.

Metabolomics analysis of Actinosynnema pretiosum with improved AP-3 production by enhancing UDP-glucose biosynthesis

Ansamitocin P-3 (AP-3) shows strong anticancer effects and has used as a payload for antibody-drug conjugates. Our previous study have shown that although genetically engineered Actinosynnema pretiosum strains with enhanced UDP-glucose (UDPG) biosynthesis displayed improved AP-3 production compared to the wild-type strain, the increase in yield was far from meeting the industrial demand. In this study, comparative metabolomics analysis complemented with quantitative real-time PCR analysis was performed for the wild-type strain and two mutants (OpgmOugp, ΔzwfΔgnd) to identify possible metabolic bottlenecks and non-intuitive targets for further enhancement of AP-3 production. We observed that enhancing intracellular UDPG availability facilitated the accumulation of intracellular N-demethyl-AP-3 and AP-3, where the transporting of them outside the cell still needs to be developed. We also found that the UDPG biosynthesis was closely associated with the availability of fructose in the medium and a suitable fructose feeding strategy could promote the further improvement of AP-3 titer. In addition, pathway abundance analysis revealed that undesired fatty acid accumulation and down-regulation of amino acid metabolism may be unfavorable for ansamitocin biosynthesis in later stage of production. These results indicate that genetic modification of the UDPG biosynthetic pathways may have pleiotropic effects on AP-3 production. Efforts must be made to eliminate these newly identified metabolic bottlenecks to boost AP-3 production in A. pretiosum.

Metabolomic change and pathway profiling reveal enhanced ansamitocin P-3 production in Actinosynnema pretiosum with low organic nitrogen availability in culture medium

Ansamitocin P-3 (AP-3), a 19-membered polyketide macrocyclic lactam, has potent antitumor activity. Our previous study showed that a relatively low organic nitrogen concentration in culture medium could significantly improve AP-3 production of Actinosynnema pretiosum. In the present study, we aimed to reveal the possible reasons for this improvement through metabolomic and gene transcriptional analytical methods. At the same time, a metabolic pathway profile based on metabolome data and pathway correlation information was performed to obtain a systematic view of the metabolic network modulations of A. pretiosum. Orthogonal partial least squares discriminant analysis showed that nine and eleven key metabolites directly associated with AP-3 production at growth phase and ansamitocin production phase, respectively. In-depth pathway analysis results highlighted that low organic nitrogen availability had significant impacts on central carbon metabolism and amino acid metabolic pathways of A. pretiosum and these metabolic responses were found to be beneficial to precursor supply and ansamitocin biosynthesis. Furthermore, real-time PCR results showed that the transcription of genes involved in precursor and ansamitocin biosynthetic pathways were remarkably upregulated under low organic nitrogen condition thus directing increased carbon flux toward ansamitocin biosynthesis. More importantly, the metabolic pathway analysis demonstrated a competitive relationship between fatty acid and AP-3 biosynthesis could significantly affect the accumulation of AP-3. Our findings provided new knowledge on the organic nitrogen metabolism and ansamitocin biosynthetic precursor in A. pretiosum and identified several important rate-limiting steps involved in ansamitocin biosynthesis thus providing a theoretical basis of further improvement in AP-3 production.