Antibody-Drug Conjugates: Functional Principles and Applications in Oncology and Beyond

Pioneering the Way: The Revolutionary Potential of Antibody-Drug Conjugates in NSCLC

OPINION STATEMENT

Despite targeted therapy and immunotherapy being recognized as established frontline treatments for advanced non-small cell lung cancer (NSCLC), the unavoidable development of resistance and disease progression poses ongoing challenges. Antibody-drug conjugates (ADCs) offer a potent treatment option for NSCLC through the specific delivery of cytotoxic agents to tumor cells that display distinct antigens. This review delves into the latest evidence regarding promising ADC agents for NSCLC, focusing on their targets, effectiveness, and safety assessments. Additionally, our study provides insights into managing toxicities, identifying biomarkers, devising methods to counter resistance mechanisms, tackling prevailing challenges, and outlining prospects for the clinical implementation of these innovative ADCs and combination regimens in NSCLC.

New Emerging Targets in Cancer Immunotherapy: The Role of B7-H3

Immune checkpoints (ICs) are molecules implicated in the fine-tuning of immune response via co-inhibitory or co-stimulatory signals, and serve to secure minimized host damage. Targeting ICs with various therapeutic modalities, including checkpoint inhibitors/monoclonal antibodies (mAbs), antibody-drug conjugates (ADCs), and CAR-T cells has produced remarkable results, especially in immunogenic tumors, setting a paradigm shift in cancer therapeutics through the incorporation of these IC-targeted treatments. However, the large proportion of subjects who experience primary or secondary resistance to available IC-targeted options necessitates further advancements that render immunotherapy beneficial for a larger patient pool with longer duration of response. B7-H3 (B7 Homolog 3 Protein, CD276) is a member of the B7 family of IC proteins that exerts pleiotropic immunomodulatory effects both in physiologic and pathologic contexts. Mounting evidence has demonstrated an aberrant expression of B7-H3 in various solid malignancies, including tumors less sensitive to current immunotherapeutic options, and has associated its expression with advanced disease, worse patient survival and impaired response to IC-based regimens. Anti-B7-H3 agents, including novel mAbs, bispecific antibodies, ADCs, CAR-T cells, and radioimmunotherapy agents, have exhibited encouraging antitumor activity in preclinical models and have recently entered clinical testing for several cancer types. In the present review, we concisely present the functional implications of B7-H3 and discuss the latest evidence regarding its prognostic significance and therapeutic potential in solid malignancies, with emphasis on anti-B7-H3 modalities that are currently evaluated in clinical trial settings. Better understanding of B7-H3 intricate interactions in the tumor microenvironment will expand the oncological utility of anti-B7-H3 agents and further shape their role in cancer therapeutics.

Phase I dose escalation study and pilot efficacy analysis of LXI-15029, a novel mTOR dual inhibitor, in Chinese subjects with advanced malignant solid tumors

BACKGROUND

The mammalian target of rapamycin (mTOR) kinase, a central component of the PI3K/AKT/mTOR pathway, plays a critical role in tumor biology as an attractive therapeutic target. We conducted this first-in-human study to investigate the safety, pharmacokinetics (PK), and pilot efficacy of LXI-15029, an mTORC1/2 dual inhibitor, in Chinese patients with advanced malignant solid tumors.

METHODS

Eligible patients with advanced, unresectable malignant solid tumors after failure of routine therapy or with no standard treatment were enrolled to receive ascending doses (10, 20, 40, 60, 80, 110, and 150 mg) of oral LXI-15029 twice daily (BID) (3 + 3 dose-escalation pattern) until disease progression or intolerable adverse events (AEs). The primary endpoints were safety and tolerability.

RESULTS

Between June 2017 and July 2021, a total of 24 patients were enrolled. LXI-15029 was well tolerated at all doses. Only one dose-limiting toxicity (grade 3 increased alanine aminotransferase) occurred in the 150 mg group, and the maximum tolerated dose was 110 mg BID. The most common treatment-related AEs were leukocytopenia (41.7%), increased alanine aminotransferase (20.8%), increased aspartate aminotransferase (20.8%), prolonged electrocardiogram QT interval (20.8%), and hypertriglyceridemia (20.8%). No other serious treatment-related AEs were reported. LXI-15029 was absorbed rapidly after oral administration. The increases in the peak concentration and the area under the curve were greater than dose proportionality over the dose range. Eight patients had stable disease. The disease control rate was 40.0% (8/20; 95% CI 21.7-60.6). In evaluable patients, the median progression-free survival was 29 days (range 29-141).

CONCLUSIONS

LXI-15029 demonstrated reasonable safety and tolerability profiles and encouraging preliminary antitumor activity in Chinese patients with advanced malignant solid tumors, which warranted further validation in phase II trials.

TRIAL REGISTRATION

NCT03125746(24/04/2017), http://ClinicalTrials.gov/show/NCT03125746.

The Evolving Landscape of Antibody-Drug Conjugates: In Depth Analysis of Recent Research Progress

Antibody-drug conjugates (ADCs) are targeted immunoconjugate constructs that integrate the potency of cytotoxic drugs with the selectivity of monoclonal antibodies, minimizing damage to healthy cells and reducing systemic toxicity. Their design allows for higher doses of the cytotoxic drug to be administered, potentially increasing efficacy. They are currently among the most promising drug classes in oncology, with efforts to expand their application for nononcological indications and in combination therapies. Here we provide a detailed overview of the recent advances in ADC research and consider future directions and challenges in promoting this promising platform to widespread therapeutic use. We examine data from the CAS Content Collection, the largest human-curated collection of published scientific information, and analyze the publication landscape of recent research to reveal the exploration trends in published documents and to provide insights into the scientific advances in the area. We also discuss the evolution of the key concepts in the field, the major technologies, and their development pipelines with company research focuses, disease targets, development stages, and publication and investment trends. A comprehensive concept map has been created based on the documents in the CAS Content Collection. We hope that this report can serve as a useful resource for understanding the current state of knowledge in the field of ADCs and the remaining challenges to fulfill their potential.

Antibody-Drug Conjugates: Ushering in a New Era of Cancer Therapy

Antibody-drug conjugates (ADCs) have provided new therapeutic options and significant promise for patients with cancer, particularly where existing treatments are limited. Substantial effort in ADC development is underway globally, with 13 ADCs currently approved and many more in development. The therapeutic benefits of ADCs leverage the ability to selectively target cancer cells through antibody binding, resultant relative sparing of non-malignant tissues, and the targeted delivery of a cytotoxic payload. Consequently, this drug class has demonstrated activity in multiple malignancies refractory to standard therapeutic options. Despite this, limitations exist, including narrow therapeutic windows, unique toxicity profiles, development of therapeutic resistance, and appropriate biomarker selection. This review will describe the development of ADCs, their mechanisms of action, pivotal trials, and approved indications and identify common themes. Current challenges and opportunities will be discussed for this drug class in cancer therapeutics at a time when significant developments in antibody therapies, immunotherapy, and targeted agents are occurring.

An Overview of the Development and Preclinical Evaluation of Antibody-Drug Conjugates for Non-Oncological Applications

Typically, antibody-drug conjugates (ADCs) are made up of a humanized antibody and a small-molecule medication connected by a chemical linker. ADCs' ability to deliver cytotoxic agents to the specific site with reduced side effects showed promising results in oncology. To date, fourteen ADCs have been approved by the US Food and Drug Administration, and approximately 297 ADCs are in pre-clinical/clinical stages in the oncology area. Inspired by these outcomes, a few scientists explored the potential of antibody-drug conjugates in non-oncological conditions such as arthritis, myasthenia gravis, immunological disorders, and kidney failure. However, there are limited data available on the non-oncological applications of antibody-drug conjugates. This current review focuses on the non-oncological applications of antibody-drug conjugates, their developmental studies, testing procedures, in vitro evaluations, and pre-clinical testing. Additionally, a summary of the restrictions, difficulties, and prospects for ADCs in non-oncological applications is provided.

Arising Novel Agents in Lung Cancer: Are Bispecifics and ADCs the New Paradigm?

Lung cancer is one of the most common cancers with the highest mortality. Non-small cell lung cancer (NSCLC) contributes to around 85% of lung cancer diagnoses (vs. 15% for small cell lung cancer). The treatment of NSCLC has vastly changed in the last two decades since the development of immunotherapy and targeted therapy against driver mutations. As is the nature of malignancy, cancer cells have acquired resistance to these treatments prompting an investigation into novel treatments and new targets. Bispecific antibodies, capable of targeting multiple substrates at once, and antibody-drug conjugates that can preferentially deliver chemotherapy to tumor cells are examples of this innovation. From our initial evaluation, both treatment modalities appear promising.

Advances in Targeted Therapy of Breast Cancer with Antibody-Drug Conjugate

Antibody-drug conjugates (ADCs) are a potential and promising therapy for a wide variety of cancers, including breast cancer. ADC-based drugs represent a rapidly growing field of breast cancer therapy. Various ADC drug therapies have progressed over the past decade and have generated diverse opportunities for designing of state-of-the-art ADCs. Clinical progress with ADCs for the targeted therapy of breast cancer have shown promise. Off-target toxicities and drug resistance to ADC-based therapy have hampered effective therapy development due to the intracellular mechanism of action and limited antigen expression on breast tumors. However, innovative non-internalizing ADCs targeting the tumor microenvironment (TME) component and extracellular payload delivery mechanisms have led to reduced drug resistance and enhanced ADC effectiveness. Novel ADC drugs may deliver potent cytotoxic agents to breast tumor cells with reduced off-target effects, which may overcome difficulties related to delivery efficiency and enhance the therapeutic efficacy of cytotoxic cancer drugs for breast cancer therapy. This review discusses the development of ADC-based targeted breast cancer therapy and the clinical translation of ADC drugs for breast cancer treatment.

Payload diversification: a key step in the development of antibody-drug conjugates

Antibody-drug conjugates (ADCs) is a fast moving class of targeted biotherapeutics that currently combines the selectivity of monoclonal antibodies with the potency of a payload consisting of cytotoxic agents. For many years microtubule targeting and DNA-intercalating agents were at the forefront of ADC development. The recent approval and clinical success of trastuzumab deruxtecan (Enhertu^®) and sacituzumab govitecan (Trodelvy^®), two topoisomerase 1 inhibitor-based ADCs, has shown the potential of conjugating unconventional payloads with differentiated mechanisms of action. Among future developments in the ADC field, payload diversification is expected to play a key role as illustrated by a growing number of preclinical and clinical stage unconventional payload-conjugated ADCs. This review presents a comprehensive overview of validated, forgotten and newly developed payloads with different mechanisms of action.

Privileged Scaffolds in Drug Discovery against Human Epidermal Growth Factor Receptor 2 for Cancer Treatment

HER2 is the membrane receptor tyrosine kinase showing overexpression in several human malignancies, particularly breast cancer. HER2 overexpression causes the activation of Ras- MAPK and PI3K/Akt/ NF-κB cellular signal transduction pathways that lead to cancer development and progression. HER2 is, therefore, presumed as one of the key targets for the development of tumor-specific therapies. Several preclinical have been developed that function by inhibiting the HER2 tyrosine kinase activity through the prevention of the dimerization process. Most HER2 inhibitors act as ATP competitors and prevent the process of phosphorylation, and abort the cell cycle progression and proliferation. In this review, the clinical drug candidates and potent pre-clinical newly developed molecules are described, and the core chemical scaffolds typically responsible for anti-HER2 activity are deciphered. In addition, the monoclonal antibodies that are either used in monotherapy or in combination therapy against HER2-positive cancer are briefly described. The identified key moieties in this study could result in the discovery of more effective HER2-targeted anticancer drug molecules and circumvent the development of resistance by HER2-specific chemotherapeutics in the future.

Trends and Perspectives of Biological Drug Approvals by the FDA: A Review from 2015 to 2021

Despite belonging to a relatively new class of pharmaceuticals, biological drugs have been used since the 1980s, when they brought about a breakthrough in the treatment of chronic diseases, especially cancer. They conquered a large space in the pipeline of the pharmaceutical industry and boosted the innovation portfolio and arsenal of therapeutic compounds available. Here, we report on biological drug approvals by the US Food and Drug Administration (FDA) from 2015 to 2021. The number of drugs included in this class grew over this period, totaling 90 approvals, with an average of 13 authorizations per year. This figure contrasts with previous periods, which registered between 2 and 8 approvals per year. We highlight the great potential and advantages of biological drugs. In this context, these therapeutics show high efficacy and high selectivity, and they have brought about a significant increase in patient survival and a reduction of adverse reactions. The development and production of biopharmaceuticals pose a major challenge because these processes require cutting-edge technology, thereby making the drugs very expensive. However, we believe that, in the near future, biological medicines will be more accessible and new drugs belonging to this class will become available as new technologies emerge. Such advances will enhance the production of these biopharmaceuticals, thereby making the process increasingly profitable and less expensive, thereby bringing about greater availability of these drugs.

Antibody-Drug Conjugates for Immunology

The application of antibody-drug conjugates (ADCs) to fields outside of oncology is increasing but is still relatively uncommon. A recent publication describes the conjugation of glucocorticoid receptor modulators to antibodies as a means of improving the separation between desired anti-inflammatory activity and unwanted systemic side effects.

A homogeneous high-DAR antibody-drug conjugate platform combining THIOMAB antibodies and XTEN polypeptides

The antibody-drug conjugate (ADC) is a well-validated modality for the cell-specific delivery of small molecules with impact expanding rapidly beyond their originally-intended purpose of treating cancer. However, antibody-mediated delivery (AMD)...

FGF/FGFR-Dependent Molecular Mechanisms Underlying Anti-Cancer Drug Resistance

Simple Summary

Deregulation of the FGF/FGFR axis is associated with many types of cancer and contributes to the development of chemoresistance, limiting the effectiveness of current treatment strategies. There are several mechanisms involved in this phenomenon, including cross-talks with other signaling pathways, avoidance of apoptosis, stimulation of angiogenesis, and initiation of EMT. Here, we provide an overview of current research and approaches focusing on targeting components of the FGFR/FGF signaling module to overcome drug resistance during anti-cancer therapy.

Abstract

Increased expression of both FGF proteins and their receptors observed in many cancers is often associated with the development of chemoresistance, limiting the effectiveness of currently used anti-cancer therapies. Malfunctioning of the FGF/FGFR axis in cancer cells generates a number of molecular mechanisms that may affect the sensitivity of tumors to the applied drugs. Of key importance is the deregulation of cell signaling, which can lead to increased cell proliferation, survival, and motility, and ultimately to malignancy. Signaling pathways activated by FGFRs inhibit apoptosis, reducing the cytotoxic effect of some anti-cancer drugs. FGFRs-dependent signaling may also initiate angiogenesis and EMT, which facilitates metastasis and also correlates with drug resistance. Therefore, treatment strategies based on FGF/FGFR inhibition (using receptor inhibitors, ligand traps, monoclonal antibodies, or microRNAs) appear to be extremely promising. However, this approach may lead to further development of resistance through acquisition of specific mutations, metabolism switching, and molecular cross-talks. This review brings together information on the mechanisms underlying the involvement of the FGF/FGFR axis in the generation of drug resistance in cancer and highlights the need for further research to overcome this serious problem with novel therapeutic strategies.