Antibody-Drug Conjugates and Targeted Treatment Strategies for Hepatocellular Carcinoma: A Drug-Delivery Perspective

Increased understanding of cancer biology, pharmacology and drug delivery has provided a new framework for drug discovery and product development that relies on the unique expression of specific macromolecules (i.e., antigens) on the surface of tumour cells. This has enabled the development of anti-cancer treatments that combine the selectivity of antibodies with the efficacy of highly potent chemotherapeutic small molecules, called antibody-drug conjugates (ADCs). ADCs are composed of a cytotoxic drug covalently linked to an antibody which then selectively binds to a highly expressed antigen on a cancer cell; the conjugate is then internalized by the cell where it releases the potent cytotoxic drug and efficiently kills the tumour cell. There are, however, many challenges in the development of ADCs, mainly around optimizing the therapeutic/safety benefits. These challenges are discussed in this review; they include issues with the plasma stability and half-life of the ADC, its transport from blood into and distribution throughout the tumour compartment, cancer cell antigen expression and the ADC binding affinity to the target antigen, the cell internalization process, cleaving of the cytotoxic drug from the ADC, and the cytotoxic effect of the drug on the target cells. Finally, we present a summary of some of the experimental ADC strategies used in the treatment of hepatocellular carcinoma, from the recent literature.

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Monoclonal Antibodies, Bispecific Antibodies and Antibody-Drug Conjugates in Oncohematology

Recent Patents on Anti-Cancer Drug Discovery ◽

10.2174/1574892815666200925120717 ◽

2020 ◽

Vol 15 (4) ◽

pp. 272-292

Author(s):

Romeo G. Mihăilă

Keyword(s):

Monoclonal Antibodies ◽

Target Cell ◽

Residual Disease ◽

Standard Of Care ◽

Bispecific Antibodies ◽

Target Antigen ◽

Target Cells ◽

Antibody Drug Conjugates ◽

Drug Conjugates ◽

Antibody Drug

Background: The therapeutic outcomes and the prognosis of patients with various hematologic malignancies are not always ideal with the current standard of care. Objective: The aim of this study is to analyze the results of the use of monoclonal antibodies, bispecific antibodies and antibody-drug conjugates for the therapy of malignant hemopathies. Methods: A mini-review was achieved using the articles published in Web of Science and PubMed between January 2017 and January 2020 and the new patents were made in this field. Results: Naked monoclonal antibodies have improved the therapeutic results obtained with standard of care, but they also have side effects and the use of some of them can lead to the loss of the target antigen through trogocytosis, which explains the resistance that occurs during therapy. The results obtained with naked monoclonal antibodies have been improved by a better monoclonal antibody preparation, the use of bispecific antibodies (against two antigens on the target cell surface or by binding both surface antigen on target cells and T-cell receptor complex, followed by cytotoxic T-lymphocytes activation and subsequent cytolysis of the target cell), the use of monoclonal or bispecific constructs in frontline regimens, combining immunotherapy with chemotherapy, including through the use of antibody-drug conjugates (which provides a targeted release of a chemotherapeutic agent). Conclusion: Immunotherapy and immuno-chemotherapy have improved the outcome of the patients with malignant hemopathies through a targeted, personalized therapy, with reduced systemic toxicity, which in some cases can even induce deep complete remissions, including minimal residual disease negativity.

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620 Tumor cell-intrinsic STING pathway is activated in the presence of cues from immune cells and contributes to the anti-tumor activity of tumor cell-targeted STING agonist antibody-drug conjugates

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0620 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A656-A656

Author(s):

Naniye Malli Cetinbas ◽

Travis Monnell ◽

Winnie Lee ◽

Kalli Catcott ◽

Chen-Ni Chin ◽

...

Keyword(s):

Tumor Cell ◽

Cancer Cell ◽

Immune Cells ◽

Antibody Drug Conjugates ◽

Drug Conjugates ◽

Primary Monocyte ◽

Sting Pathway ◽

Anti Tumor Activity ◽

Antibody Drug

BackgroundSTING pathway agonism has emerged as a potential therapeutic mechanism to stimulate an innate anti-tumor immune response. While in principle systemic administration of a STING agonist would have many therapeutic benefits, including the delivery of STING to all tumor lesions, such an approach may be limited by toxicity. Antibody-drug conjugates (ADCs) constitute a proven therapeutic modality that is ideally suited to allow systemic administration while stimulating the innate immunity in a targeted manner. We have previously demonstrated that targeted delivery of a STING agonist with an ADC induces robust anti-tumor immune responses.MethodsHerein we investigated the mechanism of action of tumor cell-targeted STING agonist ADCs. We evaluated STING pathway activation and anti-tumor activity elicited by ADCs harboring either wild type (wt) or mutant Fc deficient in Fcγ receptor (FcγR) binding in wt or STING knockout (ko) cancer cell mono-cultures, immune cell co-cultures, and in in vivo tumor models.ResultsConsistent with previous reports, the majority of cancer cell lines tested failed to induce STING pathway following STING agonist payload treatment in mono-cultures. In cancer cell:THP1 monocytic cell co-cultures, tumor-targeted STING agonist ADCs with wt Fc exhibited robust STING activation, whereas Fc-mutant ADCs or non-targeted control ADCs had minimal activity. Similar results were obtained when THP1 cells were treated in plates coated with target antigen without cancer cells, demonstrating STING activation in THP1 cells following FcγR-mediated uptake of antigen-bound ADCs. Tumor-targeted Fc-wt ADCs led to marked induction of STING pathway and cancer cell-killing in cancer cell:PBMC or primary monocyte co-cultures, and complete tumor regressions in in vivo tumors. Surprisingly, while at reduced levels relative to the Fc-wt ADCs, Fc-mutant ADCs exhibited significant activity in these in vitro and in vivo models, suggesting that tumor cell-intrinsic STING pathway may be activated in the presence of cues from immune cells. Consistently, STING agonist payload treatment in the presence of conditioned media from PBMC and primary monocyte but not from THP1 cultures, led to STING activation in cancer cell mono-cultures. Moreover, Fc-mutant ADCs had diminished activity in STING ko cancer cell:PBMC or primary monocyte co-cultures, demonstrating the contribution of tumor cell-intrinsic STING activation to the anti-tumor activity elicited by tumor cell-targeted STING agonist ADCs.ConclusionsIn conclusion, we demonstrated that tumor cell-targeted STING agonist ADCs induce robust anti-tumor activity through mechanisms involving both FcγR and tumor antigen-mediated ADC internalization and subsequent induction of STING pathway in immune cells and tumor cells.

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Antibody–Drug Conjugates for the Treatment of Breast Cancer

Cancers ◽

10.3390/cancers13122898 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2898

Author(s):

Chiara Corti ◽

Federica Giugliano ◽

Eleonora Nicolò ◽

Liliana Ascione ◽

Giuseppe Curigliano

Keyword(s):

Breast Cancer ◽

Bystander Effect ◽

Metastatic Breast ◽

Therapeutic Index ◽

Cytotoxic Agents ◽

Target Antigen ◽

Her2 Positive ◽

Antibody Drug Conjugates ◽

Drug Conjugates ◽

Antibody Drug

Metastatic breast cancer (BC) is currently an incurable disease. Besides endocrine therapy and targeted agents, chemotherapy is often used in the treatment of this disease. However, lack of tumor specificity and toxicity associated with dose exposure limit the manageability of cytotoxic agents. Antibody–drug conjugates (ADCs) are a relatively new class of anticancer drugs. By merging the selectivity of monoclonal antibodies with the cytotoxic properties of chemotherapy, they improve the therapeutic index of antineoplastic agents. Three core components characterize ADCs: the antibody, directed to a target antigen; the payload, typically a cytotoxic agent; a linker, connecting the antibody to the payload. The most studied target antigen is HER2 with some agents, such as trastuzumab deruxtecan, showing activity not only in HER2-positive, but also in HER2-low BC patients, possibly due to a bystander effect. This property to provide a cytotoxic impact also against off-target cancer cells may overcome the intratumoral heterogeneity of some target antigens. Other cancer-associated antigens represent a strategy for the development of ADCs against triple-negative BC, as shown by the recent approval of sacituzumab govitecan. In this review, we discuss the current landscape of ADC development for the treatment of BC, as well as the possible limitations of this treatment.

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Axially-substituted silicon phthalocyanine payloads for antibody-drug conjugates

Synlett ◽

10.1055/a-1503-6425 ◽

2021 ◽

Author(s):

Kazuki Takahashi ◽

Akira Sugiyama ◽

Kei Ohkubo ◽

Toshifumi Tatsumi ◽

Tatsuhiko Kodama ◽

...

Keyword(s):

Cell Lines ◽

Cancer Cell ◽

Cancer Cell Lines ◽

Antibody Drug Conjugate ◽

Antibody Drug Conjugates ◽

Drug Conjugate ◽

Drug Conjugates ◽

Antibody Drug ◽

Silicon Phthalocyanine

IR700, a silicon phthalocyanine (SiPc) photosensitizer, is an antibody-drug conjugate payload used clinically. It is, however, the sole SiPc payload to date, possibly due to the difficulty of its synthesis, resulting from its asymmetric phathalocyanine skeleton. Here we report a new axially-substituted SiPc payload with easier synthesis. Trastuzumab conjugated with the SiPc showed light- and antigen-dependent cytotoxicity in HER2-overexpressed cancer cell lines.

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Antibody–drug conjugates: targeted drug delivery for cancer

Current Opinion in Chemical Biology ◽

10.1016/j.cbpa.2010.06.170 ◽

2010 ◽

Vol 14 (4) ◽

pp. 529-537 ◽

Cited By ~ 448

Author(s):

Stephen C Alley ◽

Nicole M Okeley ◽

Peter D Senter

Keyword(s):

Drug Delivery ◽

Targeted Drug Delivery ◽

Antibody Drug Conjugates ◽

Drug Conjugates ◽

Targeted Drug ◽

Antibody Drug

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Antibody-Drug Conjugates Designed to Eradicate Tumors with Homogeneous and Heterogeneous Expression of the Target Antigen

Cancer Research ◽

10.1158/0008-5472.can-05-3973 ◽

2006 ◽

Vol 66 (6) ◽

pp. 3214-3221 ◽

Cited By ~ 251

Author(s):

Yelena V. Kovtun ◽

Charlene A. Audette ◽

Yumei Ye ◽

Hongsheng Xie ◽

Mary F. Ruberti ◽

...

Keyword(s):

Target Antigen ◽

Antibody Drug Conjugates ◽

Drug Conjugates ◽

Heterogeneous Expression ◽

Antibody Drug

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Antibody-Drug-Conjugates for Breast Cancer

Oncology Research and Treatment ◽

10.1159/000521499 ◽

2021 ◽

Author(s):

Frederik Marmé

Keyword(s):

Breast Cancer ◽

Bystander Effect ◽

Systemic Exposure ◽

Clinical Development ◽

Therapeutic Window ◽

Target Cells ◽

Magic Bullet ◽

Antibody Drug Conjugates ◽

Drug Conjugates ◽

Antibody Drug

Background Despite the advances that have been made to improve conventional chemotherapies, their use is limited by a narrow therapeutic window based on off-target toxicities. Antibody-drug-conjugates (ADCs) are composed of an antibody and a toxic payload covalently coupled by a chemical linker. They constitute an elegant means to tackle the limitations of conventional chemotherapeutics by selectively delivering a highly toxic payload directly to target cells and thereby increasing efficacy of the delivered cytotoxic but at the same time limiting systemic exposure and toxicities. As such they appear inspired by Paul Ehrlich´s concept of a “magic bullet”, which he envisioned as drugs that go directly to their target to attack pathogens but remain harmless in healthy tissues. Summary The concept of conjugating drugs to antibodies via chemical linkers is not new. As early as in the 1960s researchers started to investigate such ADCs in animal models and first clinical trials based on mouse antibodies began in the 1980s. Although the concept appears relatively straightforward, ADCs are highly complex molecules, and it took several decades of research and development until the first ADC became approved by the FDA in 2000 and the second followed not until 11 years later. The development of an effective ADC is highly demanding, and each individual component of an ADC must be optimized: the target, the antibody, the linker and its conjugation chemistry as well as the cytotoxic payload. Today there are 9 approved ADCs overall and 3 for breast cancer. So, the pace of development seems to pick up with over 100 candidates in various stages of clinical development. Many ADCs of the newest generation are optimized to elicit a so-called bystander effect, to increase efficacy and tackle heterogneous antigen expression. This approach requires a balancing of efficacy and systemic toxicity. Hence, ADCs based on their complex biology cause relevant toxicities, which are characteristic for each specific compound and may include hematologic toxicities, elevated transaminases, gastrointestinal events, pneumonitis but also ocular toxicities as well as others many physicians may initially not be very familiar with. Management of the side effects will be key to the successful clinical use of these potent drugs. Key Messages This review focusses on the clinical experience with ADCs approved in breast cancer as well as promising candidates in late-stage clinical development. We will discuss the mode of action, biology, and composition of ADCs and how each of these crucial components influences their properties and efficacy.

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