An insight into the pharmacology of cysteine/methionine containing peptide drugs

Since last century, peptides have emerged as potential drugs with >90 FDA approvals for various targets with several in the pipeline. Sulphur, in peptides is present either as thiol (-SH) from Cys or thioether from Met. In this review, all the peptides approved by FDA since 2000 containing sulphur have been included. Among them ∼50 % contains disulphide bridges. This clearly demonstrates the significance of disulphide bonds in peptide drugs. This can be achieved synthetically by using orthogonal protecting groups (PGs) for -SH. These PGs are compatible with Solid Phase Peptide Synthesis (SPPS), which is still the method of choice for peptide synthesis. The orthogonal PGs used for Cys thiol side chain protecting for disulphide bond formation have been included which are currently in use both by academia and industry from small scale to large scale synthesis. In addition, the details of the FDA approved drugs containing Cys and Met (or both) have also been discussed.

Safety evaluation of Datopotamab deruxtecan for triple-negative breast cancer: a meta-analysis

BACKGROUND

TROP-2 is emerging as a valid and fruitful strategy in triple-negative breast cancer (TNBC) patients, and several agents are currently under evaluation, including Datopotamab deruxtecan (Dato-DXd).

RESEARCH DESIGN AND METHODS

Herein, we performed a meta-analysis aimed to evaluate any grade adverse events, grade 3-4 adverse events, dose reduction, and serious adverse events in TNBC patients treated with Dato-DXd in clinical trials.

RESULTS

The pooled results suggests that Dato-DXd is associated with a favorable safety profile: while any grade treatment-related toxicities were common, grade 3-4 events were not particularly frequent and mainly represented by stomatitis (13.88%; 95% CI, 10.68 - 17.09).

CONCLUSIONS

These findings may help to comprehensively define the safety profile of Dato-DXd and to assist in the design of future clinical trials in this setting.

Antibody and immunotherapy in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma and a heterogeneous B-cell disease. The majority of patients with newly diagnosed disease are cured with first-line combination immunochemotherapy treatment however, those who experience treatment failure have dismal outcomes. Antibody therapies and immunotherapy have provided the single most major advance in the treatment of DLBCL in the last 4 decades. Rituximab, the first immunotherapy, and a monoclonal antibody targeting CD20, improved DLBCL overall survival when added to chemotherapy 2 decades ago. Since then, the advent of further "naked" monoclonal antibodies that target malignant B-cells or stimulate the immune system to kill cancer, as well as antibody-drug conjugates and bispecific antibodies have all entered the DLBCL armamentarium; with 5 antibody therapy approvals in the last 6 years alone. Here we review the literature on antibodies and immunotherapies for DLBCL and the future directions involving this successful group of drugs.

Antibody-drug conjugates in HER-2 negative breast cancers with poor prognosis

Antibody drug conjugates (ADCs) comprise a rapidly growing class of targeted drugs that selectively deliver a cytotoxic agent to cancer cells, reducing the side effects associated with conventional chemotherapy. Breast cancer (BC) is a heterogeneous entity. The need for effective therapies for HER-2 negative BCs with poor prognosis, such as triple-negative or endocrine-resistant BC, remains unmet due to the lack of potential targets for treatments. These BC subtypes are not candidates for hormonal or anti-HER-2 agents. However, ongoing clinical trials exploring the use of ADCs with a wide range of targets have shown potential for this treatment modality. In this review, we present the current state of knowledge regarding the role of ADC and speculate on novel approaches including ADC combination therapies, new molecular targets, and the role of other subclasses of ADCs (bicycle drug conjugates, bispecific ADCs, immune modulating ADCs) in this clinical scenario.

Toxicity profile of antibody-drug conjugates in breast cancer: practical considerations

Antibody-drug conjugates (ADCs) represent a novel and evolving class of antineoplastic agents, constituted by monoclonal antibody linked to biologically active drugs, delivering cytotoxic compounds at the tumor site, reducing the likelihood of systemic exposure and toxicity. They are generally well tolerated, nevertheless some predictable adverse reactions need careful monitoring and timely approach. These include neutropenia, nausea and vomiting, alopecia, diarrhea, left ventricular dysfunction, ILD/pneumonitis. The mechanisms leading to drug-associated toxicities are summarized, and prophylaxis protocols and appropriate management strategies are proposed, based on current literature. This review aims to collect the most updated evidence on toxicities potentially occurring during breast cancer treatment with approved or under clinical investigation (advanced stage) ADCs. A focus is dedicated to monitoring protocols and clinical management, aimed at preventing and/or promptly address relevant problems, in order to avoid premature discontinuation or improper dose reduction.

Harnessing the Immune System: An Effective Way to Manage Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a heterogenous hematological disorder with malignant potential controlled by immunological characteristics of the tumor microenvironment. Rapid breakthrough in the molecular pathways has made immunological approaches the main anchor in the management of DLBCL, with or without chemotherapeutic agents. Rituximab was the first monoclonal antibody approved for the treatment of DLBCL. Following rituximab that transformed the therapeutic landscape, other novel immunological agents including chimeric antigen T-cell therapy have reshaped the management of relapsed/refractory DLBCL. However, resistance and refractory state remain a challenge in the management of DLBCL. For this literature review, we screened articles from Medline, Embase, Cochrane databases and the European/North American guidelines from March 2010 through October 2022 for DLBCL. Here we discuss immunological agents that will significantly affect future treatment of this aggressive type of lymphoma.

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 multispecific antibodies, must be a central focus of future studies. This review will help scientists working on developing mAbs to treat cancers more effectively.

Failure of CAR-T cell therapy in relapsed and refractory large cell lymphoma and multiple myeloma: An urgent unmet need

Since its FDA approval, chimeric antigen receptor (CAR)-T cell therapy is changing the landscape of the treatment algorithm for relapsed and refractory large cell lymphoma and multiple myeloma. While initially hailed as a game changer and received widely with great enthusiasm, the reality of treatment failure soon became a major disappointment. This situation left patients and clinicians alike wondering about the next treatment options. CAR-T cell therapy failure for aggressive lymphoma or multiple myeloma creates a very poor prognosis and the treatment options are very limited. New emerging data, however, show promise for the use of approaches that include bispecific antibodies and other strategies to rescue affected patients. In this review, we summarize the current emerging data on the treatment options for patients whose disease has relapsed or remains refractory after CAR-T cell therapy failure, an area of great unmet need.

TROP-2 directed antibody-drug conjugates (ADCs): The revolution of smart drug delivery in advanced non-small cell lung cancer (NSCLC)

BACKGROUND

Antibody drug conjugates (ADCs) represent a revolutionary drug class in cancer therapy, combining the precision of targeted therapy with the cytotoxic effects of chemotherapy. Promising activity of novel ADCs, namely Trastuzumab Deruxtecan and Patritumab Deruxtecan, has been observed in hard-to treat molecular subtypes, such as HER2-positive and heavily pretreated EGFR-mutant Non-Small Cell Lung Cancer (NSCLC). However, therapeutic advances are expected in certain subgroups of lung cancer patients, including non-oncogene-addicted NSCLC after failure of current standard of care (e.g., immunotherapy with or without chemotherapy, chemo-antiangiogenic treatment). Trophoblastic Cell Surface Antigen 2 (TROP-2) is a surface transmembrane glycoprotein member of the epithelial cell adhesion molecule (EpCAM) family. TROP-2 represents a promising therapeutic target in refractory non-oncogene-addicted NSCLC.

METHODOLOGY

We performed a systematic literature search of the clinical trials about TROP-2 directed ADCs in NSCLC referenced in the pubmed.gov database, Cochrane Library database and clinicaltrial.gov database.

RESULTS

First-in-humans ADCs targeting TROP-2, namely Sacituzumab Govitecan (SN-38) and Datopotamab Deruxtecan (Dxd), yielded promising activity signals in NSCLC with a manageable safety profile. Most common grade ≥ 3 adverse events (AEs) of Sacituzumab Govitecan included neutropenia (28 %), diarrhea (7 %), nausea (7 %), fatigue (6 %), and febrile neutropenia (4 %). Nausea and stomatitis were the most common all grade AEs with Datopotamab Deruxtecan; dyspnea, amylase increase, hyperglycemia and lymphopenia were reported as grade ≥ 3 AEs in less than 12 % of patients.

CONCLUSION

As more effective strategies are needed for patients with refractory non-oncogene-addicted NSCLC, the design of novel clinical trials with ADCs targeting TROP-2 is encouraged as both a monotherapy or combination strategy with existing agents (e.g., monoclonal antibodies targeting immune checkpoint inhibitors or chemotherapy).

What are the challenges involved in the strategies for future antibody-drug conjugate discovery and development for oncology?

INTRODUCTION

There have been significant advances in the therapeutic strategies based on monoclonal antibodies. These advances, including the modification of their format, their production, and their functionalization. have further improved their efficacy and, particularly in oncology, have helped to overcome several limitations. Nevertheless, the efficacy and safety profile of antibody drug conjugates is not yet optimal.

AREA COVERED

This article primarily summarizes the challenges that need to be addressed during the development of various strategies for the discovery of antibody-drug conjugates in oncology. The authors further provide their expert opinion and perspectives for the future/.

EXPERT OPINION

Addressing the challenges discussed in this perspective, such as by improving the specificity of targeting cancer cells, the selective site-specific conjugation of cytotoxic drugs to antibodies and developing different strategies to overcome the problem of drug resistance will likely generate a new class of ADCs and bring more value to the concept of ADCs, particularly in the treatment of cancer patients.

HER2-low breast cancer: Novel detections and treatment advances

Breast cancer (BC), which has the highest cancer incidence in women, seriously threatens women's health. Since human epidermal growth factor receptor-2 (HER2) characterization, breast cancer treatment has entered an era of individualized targeted therapy. With the emergence of anti-HER2 targeting agents, monoclonal antibodies (mAbs) and tyrosine kinase inhibitors have considerably improved the prognosis of HER2-positive BC. However, HER2-low BC, accounting for 45-55% of BC patients, is less likely to benefit from conventional HER2-targeting mAbs. The growing success of the new generation of drugs, especially promising HER2-directed antibody-drug conjugates, has changed the treatment landscape for patients with HER2-low BC, leading to a research boom. HER-2-low BC is a heterogeneous entity, and there many areas remain to be explored. In this article, we review the literature on HER2-low BC, mainly focusing on its detection assays, clinicopathological profiles and treatment landscape, and hopefully provide insight into future perspectives.

Unexpected Cardiotoxicity in Patients With HER2-Mutant NSCLC Treated With Trastuzumab Deruxtecan: A Case Report

Antibody-drug conjugates targeting receptor tyrosine-protein kinase erbB-2 (ERBB2, HER2) have emerged as promising targeted options for HER2-mutant NSCLC. Among antibody-drug conjugates targeting HER2, trastuzumab deruxtecan was found to have the most impressive efficacy and is a potential new standard of care. Drug-related interstitial lung disease remains a serious unpredictable identified risk for patients treated with trastuzumab deruxtecan, requiring careful monitoring and multidisciplinary management. We report the first two cases of drug-related cardiotoxicity with acute myocarditis that developed after the first trastuzumab deruxtecan cycle. Routine cardiovascular risk screening is advisable, with close collaboration between cardiology specialists and oncologists.

ADME and DMPK considerations for the discovery and development of antibody drug conjugates (ADCs)

 The therapeutic concept of antibody drug conjugates (ADCs) is to selectively target tumour cells with small molecule cytotoxic drugs to maximise cell kill benefit and minimise healthy tissue toxicity.An ADC generally consists of an antibody that targets a protein on the surface of tumour cells chemically linked to a warhead small molecule cytotoxic drug.To deliver the warhead to the tumour cell, the antibody must bind to the target protein and in general be internalised into the cell. Following internalisation, the cytotoxic agent can be released in the endosomal or lysosomal compartment (via different mechanisms). Diffusion or transport out of the endosome or lysosome allows the cytotoxic drug to express its cell-killing pharmacology. Alternatively, some ADCs (e.g. EDB-ADCs) rely on extracellular cleavage releasing membrane permeable warheads.One potentially important aspect of the ADC mechanism is the 'bystander effect' whereby the cytotoxic drug released in the targeted cell can diffuse out of that cell and into other (non-target expressing) tumour cells to exert its cytotoxic effect. This is important as solid tumours tend to be heterogeneous and not all cells in a tumour will express the targeted protein.The combination of large and small molecule aspects in an ADC poses significant challenges to the disposition scientist in describing the ADME properties of the entire molecule.This article will review the ADC landscape and the ADME properties of successful ADCs, with the aim of outlining best practice and providing a perspective of how the field can further facilitate the discovery and development of these important therapeutic modalities.

Novel biologic therapies in relapsed or refractory diffuse large B cell lymphoma: CAR-T is not the only answer

Patients with diffuse large B-cell lymphoma who have refractory or relapsed disease following first line treatment have a poor prognosis when treated with conventional therapies. Significant efforts have been made in recent years to bring a broad spectrum of novel targeted therapies, the most noteworthy of which is chimeric antigen receptor T-cell therapy (CAR-T). Not all patients are eligible for CAR-T given the relatively high risk of complications and limited availability. Here we discuss promising novel biologic therapies that have been introduced in the last few years and go over ongoing clinical trials in the field.

Antibody-drug conjugates: A promising novel therapeutic approach in lung cancer

Antibody-drug conjugates (ADCs) are rapidly establishing their place and have shown promising preliminary data in lung cancer with impressive response rates and survival outcomes in previously treated patients.There are several ADCs currently in clinical trials for NSCLC and small cell lung cancer (SCLC). These ADCs often have different targets which include HER2, HER3, TROP2, CEACAM5, and MET in NSCLC and DLL3 in SCLC.Here we review the safety, and efficacy of newer ADCs in lung cancer including ado-trastuzumab emtansine, trastuzumab deruxetecan, patritomab deruxetecan, datopotamab deruxetecan, sacituzumab govitecan, SAR408701, Telisotuzumab vedotin, rovalpituzumab tesirine, lorvotuzumab mertansine, and sacituzumab govitecan.  Several novel methods are underway to improve the safety and efficacy of ADCs which include increasing the drug to antibody ratio (DAR), the potency of the payload, using more innovative payloads and replacing the antibody.

Optimizing anti-body drug conjugates and radiopharmaceuticals for precision therapy: The next frontier in precision oncology

Drug delivery to select therapeutic targets for precision oncology has always been a major challenge in oncology. Anti-body drug conjugates (ADC) and radiopharmaceuticals attempt to overcome the major limitations of chemotherapy or mono-clonal antibody therapy as they provide a highly specific means of attacking the vulnerability of the cancer cell. Currently there are over 100 clinical trials in various stages of development with these agents. Years of improved understanding of ADC technology and addressing previous failures have yielded the current pipeline of ADCs with better design. The near future of ADC developmental therapeutics includes firstly continuing to improve drug design, secondly picking right targets, thirdly balancing efficacy vs toxicity, fourth understanding innate and acquired resistance mechanisms, fifth development of ADCs across pan-cancers as tissue-agnostic therapeutics, and lastly combination strategies. There is considerable excitement in the ADC developmental therapeutics and ADCs including radiopharmaceuticals are here to stay and offer to expand our pipeline of effective drugs to combat cancer.

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.

Immunotherapy in multiple myeloma

Despite available therapies, Multiple Myeloma (MM) remains an incurable hematologic malignancy. Over the past three decades, there have been tremendous developments in therapeutic options for MM. In regards to immunotherapy, Daratumumab was the first monoclonal antibody to receive FDA approval for multiple myeloma. Since then, other monoclonal antibodies such as elotuzumab and isatuximab have received FDA approval. Many clinical trials are underway investigating the efficacy of newer immunotherapies. This review summarizes recently presented and/or published data regarding this growing field, specifically regarding monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, and trispecific antibodies.

Multi-attribute method based characterization of antibody drug conjugates (ADC) at the intact and subunit levels

Antibody-drug conjugates (ADCs) represent an important class of new biopharmaceutical modalities. ADCs are highly complex and heterogeneous molecules, potentially containing numerous product-related structures, that can contribute to the quality, efficacy and safety of the product. To keep up with product life cycle related changes, wide-range and targeted characterization of product quality attributes (PQA) are of high demand. Multi-attribute methods (MAM) can screen numerous PQAs in a parallel fashion including product properties as well as product and process-related impurities. MAM is usually based on a bottom-up approach relying on the enzymatic digestion of the protein into peptides prior to mass spectrometry (MS). However, this processing workflow can result in considerable information loss, such as the drug distribution profile of an antibody-drug conjugate. Therefore, complementary MAM approaches, based on subunit and intact mass analyses, are necessary approaches offering the advantage of product identity confirmation, quantification of the different conjugated species and monitoring the drug-to-antibody ratio at the same time. In this work we introduce a high throughput MS based attribute tracking method for ADC characterization at the intact and subunit levels by simultaneously monitoring multiple PQAs. The workflow includes sample preparation and MS instrument suitability testing for heterogeneous lysine-linked ADCs, software solutions for routine PQAs tracking, method repeatability and an easy data review fitting perfectly into high throughput analyses. As methionine oxidation is one of the modifications that should be closely monitored at any step of process development, an important application to oxidative stress evaluation using forced degradation demonstrated the applicability of the workflow.

A review of Formulations of Commercially Available Antibodies

This review identified 126 commercially available antibodies approved globally between 1986 and February 2021 including 10 antibody drug conjugates, 16 biosimilars, and 3 antibody fragments. Prior to 2014 there were ≤ 5 approved each year, but after 2014 there have been ≥ 7 approved each year with the years 2017, 2019 and 2020 having the most at 17 each. A total of 136 products were identified of which 36 are lyophilized powders and 100 are solutions. The routes of administration are mainly subcutaneous or intravenous infusion with three intravenous bolus, two intravitreal, and one intramuscular. The subcutaneous products are ready-to-use solutions or reconstituted lyophilized powders that do not require dilution while most intravenous products are concentrates that require dilution into saline or another intravenous fluid prior to infusion. Most are packaged in single-dose units and the exception of multi-use is Herceptin® and its biosimilars. The package configurations are vials, prefilled autoinjectors, or prefilled syringes. A typical antibody formulation contains an antibody, an excipient to adjust tonicity or osmolality for solutions or a lyoprotectant for lyophilized powders, a buffer, and a surfactant. The ionic tonicity-adjusting excipient is mainly sodium chloride and the non-ionic osmolality-adjusting excipients include sucrose, trehalose, mannitol, maltose, and sorbitol. The lyoprotectants are trehalose and sucrose. The pH range is 4.8-8.0 and the buffers or pH-modifying agents include histidine, citrate, succinate, acetate, phosphate, glutamate, adipic acid, aspartic acid, lactic acid, tromethamine, and 2-(N-morpholino)-ethanesulfonic acid. The surfactants include mostly polysorbate 20 or polysorbate 80, with four containing poloxamer 188, and one that does not contain a surfactant but contains PEG 3350. One product does not contain a buffer, and 12 do not contain a surfactant. The viscosity-lowering excipients are sodium chloride and the amino acids arginine, glycine, proline, and lysine. Arginine may also function to adjust ionic strength and minimize aggregation. Human serum albumin is used in 2 products for intravenous infusion. Other excipients include methionine as an anti-oxidant, and EDTA or DTPA as chelating agents. The maximum volume of subcutaneous injection is 15 mL administered over 3-5 minutes, but the typically volume is 0.5-2 mL. Five fixed-dose combinations have recently been approved and four contain hyaluronidase to assist the large volume subcutaneous injection of up to 15 mL, while one is a fixed-dose combination for intravenous with three antibodies. Prefilled autoinjectors and syringes are becoming more common and many come affixed with a needle of 27-gauge or 29-gauge, while a few have a 26-gauge or a 30-gauge needle. Recent advancements include hyaluronidase to assist the large subcutaneous injection volume of 5-15 mL, fixed-dose combinations, buffer-free formulation, and smaller subcutaneous injection volume (0.1 mL).

Rova-T enhances the anti-tumor activity of anti-PD1 in a murine model of small cell lung cancer with endogenous Dll3 expression

Rovalpituzumab tesirine (Rova-T) offers a targeted therapy for ~85% of SCLC patients whose tumors express DLL3, but clinical dosing is limited due to off-target toxicities. We hypothesized that a sub-efficacious dose of Rova-T combined with anti-PD1, which alone shows a clinical benefit to ~15% of SCLC patients, might elicit a novel mechanism of action and extend clinical utility. Using a pre-clinical murine SCLC tumor model that expresses Dll3 and has an intact murine immune system, we found that sub-efficacious doses of Rova-T with anti-PD1 resulted in enhanced anti-tumor activity, compared to either monotherapy. Multiplex immunohistochemistry (IHC) showed CD4 and CD8 T-cells primarily in normal tissue immediately adjacent to the tumor. Combination treatment, but not anti-PD1 alone, increased Ki67+/CD8 T-cells and Granzyme B+/CD8 in tumors by flow cytometry and IHC. Antibody depletion of T-cell populations showed CD8+ T-cells are required for in vivo anti-tumor efficacy. Whole transcriptome analysis as well as flow cytometry and IHC showed that Rova-T activates dendritic cells and increases Ccl5, Il-12, and Icam more than anti-PD1 alone. Increased tumor expression of PDL1 and MHC1 following Rova-T treatment also supports combination with anti-PD1. Mice previously treated with Rova-T + anti-PD1 withstood tumor re-challenge, demonstrating sustained anti-tumor immunity. Collectively our pre-clinical data support clinical combination of sub-efficacious Rova-T with anti-PD1 to extend the benefit of immune checkpoint inhibitors to more SCLC patients.

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Sub-efficacious Rova-T combined with anti-PD1 regresses murine SCLC tumors.

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Anti-SCLC efficacy seen with Rova-T + anti-PD1 requires CD8 T-cells.

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Rova-T + anti-PD1 recruits and activates T-cells and dendritic cells within the tumor.

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Combination of Rova-T and anti-PD1 results in prolonged anti-tumor immunity.

Stress Temperature Studies in Small Scale Hastelloy® Drug Substance Containers Lead to Increased Extent of and Increased Variability in Antibody-Drug Conjugate and Monoclonal Antibody Aggregation: Evidence for Novel Oxidation-Induced Crosslinking in Monoclonal Antibodies

Health authorities require that suitable stability of the drug substance be shown in relevant materials of construction. ICH Q1A(R2) explicitly states that "stability studies should be conducted on drug substance packaged in a container closure system that is the same as or simulates the packaging proposed for storage and distribution". Stainless steel containers are commonly used for the long-term storage of frozen bulk drug substances (DSs). Hastelloy®-based metal containers are sometimes used due to their higher corrosion resistance and significantly lower iron content to mitigate the potential corrosion-related risks associated with high salt formulations. Despite their benefits, we have found that elevated temperature stability studies in small scale Hastelloy® containers can lead to degradation that is not representative of degradation under typical storage conditions relevant to the manufacturing process. We provide evidence for an oxidation-induced aggregation mechanism that is based on Fenton chemistry with peroxide being supplied by the autoxidation of polysorbate at stress temperatures. Further, variation in the rates of iron leaching between individual small scale containers is shown to be the cause of the variable rates of degradation through strong correlations between leached iron levels and the extents of oxidation and aggregation. The addition of a metal chelator or the removal of polysorbate from the formulation mitigates the oxidation and the non-representative behavior. Extended characterization by LC-MS and ¹⁸O labeled peptide mapping shows that a significant portion of the aggregate formed under these conditions is covalently crosslinked and that the predominant covalent species is either a dityrosine or tyrosine-tryptophan crosslink between an Fc peptide and a Fab peptide. This report is the first time either of these two crosslinks have been reported for antibodies with detailed analytical characterization. Because the behavior observed in these studies is not representative of degradation under typical storage conditions relevant to the manufacturing process, this study demonstrates that small scale stress studies in metal containers should be performed with caution and that extended incubation times can lead to non-representative degradation mechanisms.

Recent advances of antibody drug conjugates for clinical applications

Antibody drug conjugates (ADCs) normally compose of a humanized antibody and small molecular drug via a chemical linker. After decades of preclinical and clinical studies, a series of ADCs have been widely used for treating specific tumor types in the clinic such as brentuximab vedotin (Adcetris®) for relapsed Hodgkin's lymphoma and systemic anaplastic large cell lymphoma, gemtuzumab ozogamicin (Mylotarg®) for acute myeloid leukemia, ado-trastuzumab emtansine (Kadcyla®) for HER2-positive metastatic breast cancer, inotuzumab ozogamicin (Besponsa®) and most recently polatuzumab vedotin-piiq (Polivy®) for B cell malignancies. More than eighty ADCs have been investigated in different clinical stages from approximately six hundred clinical trials to date. This review summarizes the key elements of ADCs and highlights recent advances of ADCs, as well as important lessons learned from clinical data, and future directions.

An overview on anti-tubulin agents for the treatment of lymphoma patients

Anti-tubulin agents constitute a large class of compounds with broad activity both in solid tumors and hematologic malignancies, due to the interference with microtubule dynamics. Since microtubules play crucial roles in the regulation of the mitotic spindles, the interference with their function usually leads to a block in cell division with arrest at the metaphase/anaphase junction of mitosis, followed to apoptosis. This explains the reason why tubulin-binding agents (TBAs) proved to be extremely active in patients with cancer. Several anti-tubulin agents are indicated in the treatment of patients with lymphomas both alone and in combination chemotherapy regimens. The article reviews the literature on classic and more recent anti-tubulin agents, providing an insight into their mechanisms of action and their use in the treatment of lymphoma.

Redirecting extracellular proteases to molecularly guide radiosensitizing drugs to tumors

Patients with advanced cancers are treated with combined radiotherapy and chemotherapy, however curability is poor and treatment side effects severe. Drugs sensitizing tumors to radiotherapy have been developed to improve cell kill, but tumor specificity remains challenging. To achieve tumor selectivity of small molecule radiosensitizers, we tested as a strategy active tumor targeting using peptide-based drug conjugates. We attached an inhibitor of the DNA damage response to antibody or cell penetrating peptides. Antibody drug conjugates honed in on tumor overexpressed cell surface receptors with high specificity but lacked efficacy when conjugated to the DNA damage checkpoint kinase inhibitor AZD7762. As an alternative approach, we synthesized activatable cell penetrating peptide scaffolds that accumulated within tumors based on matrix metalloproteinase cleavage. While matrix metalloproteinases are integral to tumor progression, they have proven therapeutically elusive. We harnessed these pro-tumorigenic extracellular proteases to spatially guide radiosensitizer drug delivery using cleavable activatable cell penetrating peptides. Here, we tested the potential of these two drug delivery platforms targeting distinct tumor compartments in combination with radiotherapy and demonstrate the advantages of protease triggered cell penetrating peptide scaffolds over antibody drug conjugates to deliver small molecule amine radiosensitizers.

Bis(vinylsulfonyl)piperazines as efficient linkers for highly homogeneous antibody-drug conjugates

Disulfide re-bridging strategy has demonstrated significant advantages in the construction of homogeneous antibody drug conjugates (ADCs). However, a major issue that disulfide scrambling at the hinge region of antibody leads to the formation of "half-antibody" has appeared for many re-bridging linkers. We present bis(vinylsulfonyl)piperazines (BVP) as efficient linkers to selectively re-bridge disulfides at the antigen-binding fragment (Fab) regions and produce highly homogeneous conjugates with a loading of two drugs without disulfide scrambling. We also found that optically active (S)-configuration linkers led to more sufficient conjugation compared with (R)-configuration. The BVP-linked ADCs demonstrated superior efficacy and antigen-selectivity in vitro cytotoxicity.

Antibody Clustering Using a Machine Learning Pipeline that Fuses Genetic, Structural, and Physicochemical Properties

Antibody V domain clustering is of paramount importance to a repertoire of immunology-related areas. Although several approaches have been proposed for antibody clustering, still no consensus has been reached. Numerous attempts use information from genes, protein sequences, 3D structures, and 3D surfaces in an effort to elucidate unknown action mechanisms directly related to their function and to either link them directly to diseases or drive the discovery of new medicines, such as antibody drug conjugates (ADC). Herein, we describe a new V domain antibody clustering method based on the comparison of the interaction sites between each antibody and its antigen. A more specific clustering analysis of the antibody's V domain was provided using deep learning and data mining techniques. The multidimensional information was extracted from the structural resolved antibodies when they were captured to interact with other proteins. The available 3D structures of protein antigen-antibody (Ag-Ab) interfaces contain information about how antibody V domains recognize antigens as well as about which amino acids are involved in the recognition. As such, the antibody surface holds information about antigens' folding that reside with the Ab-Ag interface residues and how they interact. In order to gain insight into the nature of such interactions, we propose a new simple philosophy to transform the conserved framework (fragment regions, complementarity-determining regions) of antibody V domain in a binary form using structural features of antibody-antigen interactions, toward identifying new antibody signatures in V domain binding activity. Finally, an advanced three-level hybrid classification scheme has been set for clustering antibodies in subgroups, which can combine the information from the protein sequences, the three-dimensional structures, and specific "key patterns" of recognized interactions. The clusters provide multilevel information about antibodies and antibody-antigen complexes.

Preclinical safety profile of disitamab vedotin：a novel anti-HER2 antibody conjugated with MMAE

The HER2 pathway plays a pivotal role in cell proliferation and differentiation, while the receptor overexpression caused by amplification of HER2 gene is associated with the growth of several tumors. Previously published clinical trials have demonstrated that antibody-conjugated drugs (ADCs) remarkably improved clinical effects compared with antibodies alone for the same target. In order to provide more effective drugs, we developed Disitamab vedotin based on ADC. The antibody part was a humanized monoclonal antibody targeting HER2, the small molecule toxin was monomethyl auristatin E (MMAE), a synthetic antineoplastic agent. A protease cleavable linker covalently attached MMAE to the antibody. In this study, we characterized the toxicity profile of Disitamab vedotin through single- and repeat-dose toxicity studies in monkeys. The toxicities of small molecules and naked antibody (Disitamab) were also assessed in these studies. Monkeys were well tolerated with Disitamab vedotin at doses of 6 mg/kg, while equivalent MMAEs resulted in severe myelosuppression. This finding proves that ADCs improve the therapeutic effect. In addition, the safety profiles of Disitamab vedotin and MMAE were similar and consistent with the activation mechanism of MMAE. Toxicology finding included bone marrow/hematology toxicity and lymphoid organ toxicity, while no significant toxicity was observed in animals treated with naked antibody. These side effects were found to be consistent with data acquired from clinical phase I/II patients treated with Disitamab vedotin.

Antibody drug conjugates against the receptor for advanced glycation end products (RAGE), a novel therapeutic target in endometrial cancer

Background

The treatment of endometrial cancer (EC), the most common gynecological cancer, is currently hampered by the toxicity of current cytotoxic agents, meaning novel therapeutic approaches are urgently required.

Methods

A cohort of 161 patients was evaluated for the expression of the receptor for advanced glycation end products (RAGE) in endometrial tissues. The present study also incorporates a variety of in vitro methodologies within multiple cell lines to evaluate RAGE expression and antibody-drug conjugate efficacy, internalisation and intercellular trafficking. Additionally, we undertook in vivo bio-distribution and toxicity evaluation to determine the suitability of our chosen therapeutic approach, together with efficacy studies in a mouse xenograft model of disease.

Results

We have identified an association between over-expression of the receptor for advanced glycation end products (RAGE) and EC (H-score = Healthy: 0.46, SD 0.26; Type I EC: 2.67, SD 1.39; Type II EC: 2.20, SD 1.34; ANOVA, p < 0.0001). Furthermore, increased expression was negatively correlated with patient survival (Spearman’s Rank Order Correlation: ρ = − 0.3914, p < 0.05). To exploit this association, we developed novel RAGE-targeting antibody drug conjugates (ADC) and demonstrated the efficacy of this approach. RAGE-targeting ADCs were up to 100-fold more efficacious in EC cells compared to non-malignant cells and up to 200-fold more cytotoxic than drug treatment alone. Additionally, RAGE-targeting ADCs were not toxic in an in vivo pre-clinical mouse model, and significantly reduced tumour growth in a xenograft mouse model of disease.

Conclusions

These data, together with important design considerations implied by the present study, suggest RAGE-ADCs could be translated to novel therapeutics for EC patients.

Potential and challenges in their application as targeted therapies in cancer

Antibody drug conjugates have emerged as a very attractive type of targeted therapy in cancer. They combine the antigen-targeting specificity of monoclonal antibodies (mAbs) with the cytotoxic potency of chemotherapeutics. This review focuses on antibody drug conjugates based on metal-containing cytotoxic payloads. We will also describe antibody drug conjugates (ADCs) in which a metal-based component (mostly metallic nanoparticles) exerts a relevant function in the ADC (for photodynamic or photothermal therapy, as air-plasma-enhancer or chemo-sensitizer, as carrier of other cytotoxic payloads or as an integral part of the linker structure). Challenges and opportunities to increase the translational potential of these ADCs will be discussed.

Covalent binders in drug discovery

Covalent modulation of protein function can have multiple utilities including therapeutics, and probes to interrogate biology. While this field is still viewed with scepticism due to the potential for (idiosyncratic) toxicities, significant strides have been made in terms of understanding how to tune electrophilicity to selectively target specific residues. Progress has also been made in harnessing the potential of covalent binders to uncover novel biology and to provide an enhanced utility as payloads for Antibody Drug Conjugates. This perspective covers the tenets and applications of covalent binders.

Design and characterization of homogenous antibody-drug conjugates with a drug-to-antibody ratio of one prepared using an engineered antibody and a dual-maleimide pyrrolobenzodiazepine dimer

Most strategies used to prepare homogeneous site-specific antibody-drug conjugates (ADCs) result in ADCs with a drug-to-antibody ratio (DAR) of two. Here, we report a disulfide re-bridging strategy to prepare homogeneous ADCs with DAR of one using a dual-maleimide pyrrolobenzodiazepine (PBD) dimer (SG3710) and an engineered antibody (Flexmab), which has only one intrachain disulfide bridge at the hinge. We demonstrate that SG3710 efficiently re-bridge a Flexmab targeting human epidermal growth factor receptor 2 (HER2), and the resulting ADC was highly resistant to payload loss in serum and exhibited potent anti-tumor activity in a HER2-positive gastric carcinoma xenograft model. Moreover, this ADC was tolerated in rats at twice the dose compared to a site-specific ADC with DAR of two prepared using a single-maleimide PBD dimer (SG3249). Flexmab technologies, in combination with SG3710, provide a platform for generating site-specific homogenous PBD-based ADCs with DAR of one, which have improved biophysical properties and tolerability compared to conventional site-specific PBD-based ADCs with DAR of two.

The Future of Combination Therapies for Peripheral T Cell Lymphoma (PTCL)

PURPOSE OF REVIEW

Peripheral T cell lymphoma is a rare heterogeneous group of diseases which are characterized by poor outcomes to treatment and short overall survival. In the past decade, several new therapies targeting T cell biology have been approved in the relapsed setting. These new therapies, such as pralatrexate, romidepsin, belinostat, and brentuximab vedotin, have begun to make their way into practice. Despite these advances, outcomes have not changed dramatically. In recent years, efforts have been made to incorporate these new therapies into combination strategies to treat this challenging disease entity. Herein we will review some of the latest developments.

RECENT FINDINGS

With the new WHO classification, discrete entities of PTCL are now being identified by molecular and phenotypic markers. This new classification is critical to our ability to define disease entities which may respond to certain classes of targeted therapy. Some such mutations include genes controlling epigenetics (TET2, IDH2, DNMT3A, RHOA, CD28). As such, epigenetic therapies such as histone deacetylase (HDAC) inhibitors have become the platform to which other novel therapies or chemotherapy has been added. Early phase clinical studies have demonstrated that combination therapy with romidepsin plus other agents known to have activity in T cell lymphoma have enhanced clinical benefit for this group of diseases. In addition, the antibody drug conjugate, brentuximab vedotin has been shown to have potent activity in T cell lymphomas expressing CD30. This drug is being studied as well with other targeted therapies and chemotherapy in an effort to improve response rates and progression-free survival. Although T cell lymphomas remain a highly challenging group of diseases to treat, new efforts to leverage drugs that discretely target the biology that drives T cell lymphomagenesis in combination provide hope that improved outcomes may be realized in the near future.

Antibody Drug Conjugates in the Treatment of Epithelial Ovarian Cancer

Antibody drug conjugates are novel mechanisms for delivering chemotherapy. They vary based on the targeted antigen, conjugated cytotoxic, and the type of linker used. These differences determine what cells are targeted. There are 2 antibody drug conjugates approved for use in cancer. For epithelial ovarian cancer, more than 15 antibody drug conjugates are under study. Using antibody drug conjugates in epithelial ovarian cancer makes sense. This review discusses promising trial results demonstrating efficacy. Reported toxicities include visual disturbance. There is an absence of significant hematologic toxicity. Overlapping toxicity between standard cytotoxics and antibody drug conjugates includes neuropathy and constitutional symptoms.

Immunotherapy and Targeted Therapy for Small Cell Lung Cancer: There Is Hope

Small cell lung cancer (SCLC) is a devastating and aggressive neuroendocrine carcinoma of the lung. It accounts for ~15% of lung cancer mortality and has had no improvement in standard treatment options for nearly 30 years. However, there is now hope for change with new therapies and modalities of therapy. Immunotherapies and checkpoint inhibitors are entering clinical practice, selected targeted therapies show promise, and "smart bomb"-based drug/radioconjugates have led to good response in early clinical trials. Additionally, new research insights into the genetics and tumor heterogeneity of SCLC alongside the availability of new tools such as patient-derived or circulating tumor cell xenografts offer the potential to shine light on this beshadowed cancer.

Cancer immunotherapy beyond immune checkpoint inhibitors

Malignant cells have the capacity to rapidly grow exponentially and spread in part by suppressing, evading, and exploiting the host immune system. Immunotherapy is a form of oncologic treatment directed towards enhancing the host immune system against cancer. In recent years, manipulation of immune checkpoints or pathways has emerged as an important and effective form of immunotherapy. Agents that target cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), programmed cell death receptor-1 (PD-1), and programmed cell death ligand-1 (PD-L1) are the most widely studied and recognized. Immunotherapy, however, extends beyond immune checkpoint therapy by using new molecules such as chimeric monoclonal antibodies and antibody drug conjugates that target malignant cells and promote their destruction. Genetically modified T cells expressing chimeric antigen receptors are able to recognize specific antigens on cancer cells and subsequently activate the immune system. Native or genetically modified viruses with oncolytic activity are of great interest as, besides destroying malignant cells, they can increase anti-tumor activity in response to the release of new antigens and danger signals as a result of infection and tumor cell lysis. Vaccines are also being explored, either in the form of autologous or allogenic tumor peptide antigens, genetically modified dendritic cells that express tumor peptides, or even in the use of RNA, DNA, bacteria, or virus as vectors of specific tumor markers. Most of these agents are yet under development, but they promise to be important options to boost the host immune system to control and eliminate malignancy. In this review, we have provided detailed discussion of different forms of immunotherapy agents other than checkpoint-modifying drugs. The specific focus of this manuscript is to include first-in-human phase I and phase I/II clinical trials intended to allow the identification of those drugs that most likely will continue to develop and possibly join the immunotherapeutic arsenal in a near future.

Investigation of low recovery in the free drug assay for antibody drug conjugates by size exclusion-reversed phase two dimensional-liquid chromatography

Antibody drug conjugates (ADCs) are complex therapeutic agents combining the selectivity of monoclonal antibodies and highly efficacious small molecule drugs to successfully eliminate tumor cells while limiting the general toxicity and side effects of the therapeutic to protect patient safety. One unique attribute critical to the safety of ADCs is the residual content of unconjugated small molecule drug present from either incomplete conjugation or degradation of the ADC. Typically for quality control assays, quantifying the amount of the free drug is performed through precipitation of the protein species using an organic solvent and then assaying the amount of free drug left in the supernatant. During the validation of an assay of this type for a maleimide based linker drug, issues were experienced with low and variable recovery in the spiked samples of the drug substance and drug product. A two-dimensional heart-cutting method coupling Size Exclusion Chromatography (SEC) with Reverse Phase (RP) chromatography was utilized to explore possible mechanisms leading to the low recovery of the free linker drug. The results of the investigation indicated that the spiked linker drug reacts with residual reactive groups on the ADC; a conclusion which was confirmed by the observed increase of average Drug to Antibody Ratio (DAR) determined by Hydrophobic Interaction Chromatography (HIC). Finally, several approaches were evaluated to minimize the recovery loss. Capping the residual reactive groups on the ADC with maleimide containing reagents effectively mitigated the low recovery issue.

Considerations for the nonclinical safety evaluation of antibody drug conjugates for oncology

Antibody drug conjugates (ADCs) include monoclonal antibodies that are linked to cytotoxic small molecules. A number of these agents are currently being developed as anti-cancer agents designed to improve the therapeutic index of the cytotoxin (i.e., cytotoxic small molecule or cytotoxic agent) by specifically delivering it to tumor cells. This paper presents primary considerations for the nonclinical safety evaluation of ADCs and includes strategies for the evaluation of the entire ADC or the various individual components (i.e., antibody, linker or the cytotoxin). Considerations are presented on how to design a nonclinical safety assessment program to identify the on- and off-target toxicities to enable first-in-human (FIH) studies. Specific discussions are also included that provide details as to the need and how to conduct the studies for evaluating ADCs in genetic toxicology, tissue cross-reactivity, safety pharmacology, carcinogenicity, developmental and reproductive toxicology, biotransformation, toxicokinetic monitoring, bioanalytical assays, immunogenicity testing, test article stability and the selection of the FIH dose. Given the complexity of these molecules and our evolving understanding of their properties, there is no single all-encompassing nonclinical strategy. Instead, each ADC should be evaluated on a case-by-case scientifically-based approach that is consistent with ICH and animal research guidelines.

Adaptive Immune Responses and HER2/neu Positive Breast Cancer

Oncogenic signaling, such as HER2/neu signaling, has been shown to play major role for tumorigenesis in a subset of breast cancer patients. The use of anti-HER2/neu antibody has not only revealed the mechanisms for HER2/neu signaling but also shown a therapeutic advantage of its blockade. Indeed, the use of trastuzumab has greatly improved the treatment of HER2-positive breast cancer. Although this therapy has been used in the clinic for over twenty years, recent data is still uncovering new mechanisms by which this antibody exerts its anti-tumor activity. In addition to an improved understanding of the molecular mechanisms by which this therapy inhibits growth of tumor cells, the discovery that anti-HE2/neu therapy initiates and requires the adaptive immune system is one of these new mechanisms. The presence of anti-HER2/neu initiated adaptive immunity gives credence to efforts targeted at stimulating the immune system in treating HER2 positive breast cancer. This review focuses on the role of the inflammatory response in HER2 positive breast cancer with particular emphasis on trastuzumab therapy.

Treatment strategies for Hodgkin lymphoma recurring following autologous hematopoietic stem cell transplantation

Hodgkin lymphoma (HL) represents one of the great success stories in hematology going from a uniformly fatal disease, to one that is curable in the vast majority of cases. Despite this success, some patients experience relapse. To address this unmet need a variety of agents, classes of drugs, and strategies have demonstrated activity in HL recurring after autologous hematopoietic stem cell transplantation. These include chemotherapeutics (gemcitabine-based combinations, bendamustine), histone deacetylase (HDAC) inhibitors (panobinostat), immunomodulatory agents (lenalidomide), mTOR inhiobitors (everolimus), monoclonal antibodies (rituximab), and antibody-drug conjugates (brentuximab vedotin) as well the potential of long-term disease control via allogeneic transplantation. Such advances reflect our increased understanding of the biology of HL and hold promise for continued improved outcomes for those suffering with this condition.