Cytotoxic Payload Research Articles

Mechanisms of ADC Toxicity and Strategies to Increase ADC Tolerability.

Anti-cancer antibody-drug conjugates (ADCs) aim to expand the therapeutic index of traditional chemotherapy by employing the targeting specificity of monoclonal antibodies (mAbs) to increase the efficiency of the delivery of potent cytotoxic agents to malignant cells. In the past three years, the number of ADCs approved by the Food and Drug Administration (FDA) has tripled. Although several ADCs have demonstrated sufficient efficacy and safety to warrant FDA approval, the clinical use of all ADCs leads to substantial toxicity in treated patients, and many ADCs have failed during clinical development due to their unacceptable toxicity profiles. Analysis of the clinical data has demonstrated that dose-limiting toxicities (DLTs) are often shared by different ADCs that deliver the same cytotoxic payload, independent of the antigen that is targeted and/or the type of cancer that is treated. DLTs are commonly associated with cells and tissues that do not express the targeted antigen (i.e., off-target toxicity), and often limit ADC dosage to levels below those required for optimal anti-cancer effects. In this manuscript, we review the fundamental mechanisms contributing to ADC toxicity, we summarize common ADC treatment-related adverse events, and we discuss several approaches to mitigating ADC toxicity.

Stability assessment of Polatuzumab vedotin and Brentuximab vedotin using different analytical techniques

Antibody-drug conjugates (ADC) are considered to be fast-growing innovative biopharmaceuticals. The science used for conjugating potent cytotoxic payload to the targeted monoclonal antibody through a chemical linker has played a great value in the area of oncology treatment. In this study; Polatuzumab vedotin (POLA) and Brentuximab vedotin (SGN-35) were subjected to various stress conditions enclosing different pH, thermal stress, agitation, and successive cycles of freeze and thaw in order to produce potential degradation by-products and guarantee the appropriateness of the applied testing protocol. Different analytical techniques were established and validated to be used in the quantitation of the degraded products from different perspectives. The formation of ADC aggregates and fragments was monitored using SE-HPLC as well as dynamic light scattering (DLS). The drug antibody ratio (DAR) and ADC conjugation profile were determined using hydrophobic interaction chromatography (HIC-HPLC). In addition to performing a statistical interpretation of HIC-HPLC results by principal component analysis (PCA) to explicate the obtained data. Also, the quantity of the unconjugated toxic drug was quantified using RP-HPLC. Testing the binding activity of ADC to their target receptor ADC was conducted using ELISA. Results presented that used assay protocol had worked as a complementary design for characterization and stability assessment of the used ADC. Variances in the stability profile of both products were observed which could be attributed to the usage of different formulation buffers. This highlighted the importance of using multiple techniques for the assessment of the quality attributes of such sophisticated products. The analytical assay protocol should be used for the evaluation of the quality and stability of several ADC.

Targeted thorium-227 conjugates as treatment options in oncology.

Targeted alpha therapy (TAT) is a promising approach for addressing unmet needs in oncology. Inherent properties make α-emitting radionuclides well suited to cancer therapy, including high linear energy transfer (LET), penetration range of 2-10 cell layers, induction of complex double-stranded DNA breaks, and immune-stimulatory effects. Several alpha radionuclides, including radium-223 (223Ra), actinium-225 (225Ac), and thorium-227 (227Th), have been investigated. Conjugation of tumor targeting modalities, such as antibodies and small molecules, with a chelator moiety and subsequent radiolabeling with α-emitters enables specific delivery of cytotoxic payloads to different tumor types. 223Ra dichloride, approved for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) with bone-metastatic disease and no visceral metastasis, is the only approved and commercialized alpha therapy. However, 223Ra dichloride cannot currently be complexed to targeting moieties. In contrast to 223Ra, 227Th may be readily chelated, which allows radiolabeling of tumor targeting moieties to produce targeted thorium conjugates (TTCs), facilitating delivery to a broad range of tumors. TTCs have shown promise in pre-clinical studies across a range of tumor-cell expressing antigens. A clinical study in hematological malignancy targeting CD22 has demonstrated early signs of activity. Furthermore, pre-clinical studies show additive or synergistic effects when TTCs are combined with established anti-cancer therapies, for example androgen receptor inhibitors (ARI), DNA damage response inhibitors such as poly (ADP)-ribose polymerase inhibitors or ataxia telangiectasia and Rad3-related kinase inhibitors, as well as immune checkpoint inhibitors.

Application of a Biocatalytic Strategy for the Preparation of Tiancimycin-Based Antibody-Drug Conjugates Revealing Key Insights into Structure-Activity Relationships.

Antibody-drug conjugates (ADCs) are cancer chemotherapeutics that utilize a monoclonal antibody (mAb)-based delivery system, a cytotoxic payload, and a chemical linker. ADC payloads must be strategically functionalized to allow linker attachment without perturbing the potency required for ADC efficacy. We previously developed a biocatalytic system for the precise functionalization of tiancimycin (TNM)-based payloads. The TNMs are anthraquinone-fused enediynes (AFEs) and have yet to be translated into the clinic. Herein, we report the translation of biocatalytically functionalized TNMs into ADCs in combination with the dual-variable domain (DVD)-mAb platform. The DVD enables both site-specific conjugation and a plug-and-play modularity for antigen-targeting specificity. We evaluated three linker chemistries in terms of TNM-based ADC potency and antigen selectivity, demonstrating a trade-off between potency and selectivity. This represents the first application of AFE-based payloads to DVDs for ADC development, a workflow that is generalizable to further advance AFE-based ADCs for multiple cancer types.

Peptide Drug Conjugates and Their Role in Cancer Therapy.

Drug conjugates have become a significant focus of research in the field of targeted medicine for cancer treatments. Peptide-drug conjugates (PDCs), a subset of drug conjugates, are composed of carrier peptides ranging from 5 to 30 amino acid residues, toxic payloads, and linkers that connect the payload to the peptide. PDCs are further broken down into cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs), each having their own differences in the delivery of cytotoxic payloads. Generally, PDCs as compared to other drug conjugates-like antibody-drug conjugates (ADCs)-have advantages in tumor penetration, ease of synthesis and cost, and reduced off-target effects. Further, as compared to traditional cancer treatments (e.g., chemotherapy and radiation), PDCs have higher specificity for the target cancer with generally less toxic side effects in smaller doses. However, PDCs can have disadvantages such as poor stability and rapid renal clearance due to their smaller size and limited oral bioavailability due to digestion of its peptide structure. Some of these challenges can be overcome with modifications, and despite drawbacks, the intrinsic small size of PDCs with high target specificity still makes them an attractive area of research for cancer treatments.

Antibody drug conjugates beyond cytotoxic payloads.

For many years, antibody drug conjugates (ADC) have teased with the promise of targeted payload delivery to diseased cells, embracing the targeting of the antibody to which a cytotoxic payload is conjugated. During the past decade this promise has started to be realised with the approval of more than a dozen ADCs for the treatment of various cancers. Of these ADCs, brentuximab vedotin really laid the foundations of a template for a successful ADC with lysosomal payload release from a cleavable dipeptide linker, measured DAR by conjugation to the Cys-Cys interchain bonds of the antibody and a cytotoxic payload. Using this ADC design model oncology has now expanded their repertoire of payloads to include non-cytotoxic compounds. These new payload classes have their origins in prior medicinal chemistry programmes aiming to design selective oral small molecule drugs. While this may not have been achieved, the resulting compounds provide excellent starting points for ADC programmes with some compounds amenable to immediate linker attachment while for others extensive SAR and structural information offer invaluable design insights. Many of these new oncology payload classes are of interest to other therapeutic areas facilitating rapid access to drug-linkers for exploration as non-oncology ADCs. Other therapeutic areas have also pursued unique payload classes with glucocorticoid receptor modulators (GRM) being the most clinically advanced in immunology. Here, ADC payloads come full circle, as oncology is now investigating GRM payloads for the treatment of cancer. This chapter aims to cover all these new ADC approaches while describing the medicinal chemistry origins of the new non-cytotoxic payloads.

Antibody-drug conjugates: the evolving field of targeted chemotherapy for breast cancer treatment.

Antibody-drug conjugates (ADCs) are a class of antineoplastic agents whose structure is composed of three main components: a monoclonal antibody (mAB) targeting a specific target antigen, a cytotoxic payload, and a linker binding the antibody to the payload. By combining the specificity of mABs with the high potency of the payloads, ADCs constitute a smart drug delivery system with improved therapeutic index. After recognition and binding of the mAB to its target surface antigen, ADCs are internalized by endocytosis by the tumor cell, releasing the payloads into the cytoplasm, where they exert their cytotoxic activity, eventually leading to cell death. The composition of some of the new ADCs confers additional functional properties that allow expanding their activity to neighboring cells not expressing the target antigen, constituting a valuable strategy to overcome tumor heterogeneity. Some of these 'off-target effects', such as the bystander effect, are possibly the mechanism underlying the antitumor activity demonstrated in patients with low expression of the target antigens, which represents an important paradigm shift in anticancer targeted therapy. Three ADCs are currently approved for the treatment of breast cancer (BC); two anti-HER2 (human epidermal growth factor receptor 2) ADCs (trastuzumab emtansine and trastuzumab deruxtecan); and one Trop-2-targeted ADC (sacituzumab govitecan). Based on the unprecedented efficacy data demonstrated by these agents, ADCs have been incorporated as part of standard regimens for all subtypes of advanced BC, as well as for high-risk early HER2-positive BC. Despite the remarkable advances, several hurdles still remain to overcome, including the development of reliable biomarkers for patient selection, prevention, and management of potentially severe toxicities, ADC resistance mechanisms, post-ADC resistance patterns, and optimal treatment sequencing and combinations. In this review, we will summarize the currently available evidence related to the use of these agents, as well as explore the current landscape of ADC development for BC treatment.

Antibody-drug conjugates for lymphoma patients: preclinical and clinical evidences.

Antibody-drug conjugates (ADCs) are a recent, revolutionary approach for malignancies treatment, designed to provide superior efficacy and specific targeting of tumor cells, compared to systemic cytotoxic chemotherapy. Their structure combines highly potent anti-cancer drugs (payloads or warheads) and monoclonal antibodies (Abs), specific for a tumor-associated antigen, via a chemical linker. Because the sensitive targeting capabilities of monoclonal Abs allow the direct delivery of cytotoxic payloads to tumor cells, these agents leave healthy cells unharmed, reducing toxicity. Different ADCs have been approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of a wide range of malignant conditions, both as monotherapy and in combination with chemotherapy, including for lymphoma patients. Over 100 ADCs are under preclinical and clinical investigation worldwide. This paper it provides an overview of approved and promising ADCs in clinical development for the treatment of lymphoma. Each component of the ADC design, their mechanism of action, and the highlights of their clinical development progress are discussed.

Engineering of a Fully Human Anti-MUC-16 Antibody and Evaluation as a PET Imaging Agent.

Antibodies that recognize cancer biomarkers, such as MUC16, can be used as vehicles to deliver contrast agents (imaging) or cytotoxic payloads (therapy) to the site of tumors. MUC16 is overexpressed in 80% of epithelial ovarian cancer (EOC) and 65% of pancreatic ductal adenocarcinomas (PDAC), where effective 'theranostic' probes are much needed. This work aims to develop fully human antibodies against MUC16 and evaluate them as potential immuno-PET imaging probes for detecting ovarian and pancreatic cancers. We developed a fully human monoclonal antibody, M16Ab, against MUC16 using phage display. M16Ab was conjugated with p-SCN-Bn-DFO and radiolabeled with 89Zr. 89Zr-DFO-M16Ab was then evaluated for binding specificity and affinity using flow cytometry. In vivo evaluation of 89Zr-DFO-M16Ab was performed by microPET/CT imaging at different time points at 24-120 h post injection (p.i.) and ex vivo biodistribution studies in mice bearing MUC16-expressing OVCAR3, SKOV3 (ovarian) and SW1990 (pancreatic) xenografts. 89Zr-DFO-M16Ab bound specifically to MUC16-expressing cancer cells with an EC50 of 10nM. 89Zr-DFO-M16Ab was stable in serum and showed specific uptake and retention in tumor xenografts even after 120 h p.i. (microPET/CT) with tumor-to-blood ratios > 43 for the SW1990 xenograft. Specific tumor uptake was observed for SW1990/OVCAR3 xenografts but not in MUC16-negative SKOV3 xenografts. Pharmacokinetic study shows a relatively short distribution (t1/2α) and elimination half-life (t1/2ß) of 4.4 h and 99 h, respectively. In summary, 89Zr-DFO-M16Ab is an effective non-invasive imaging probe for ovarian and pancreatic cancers and shows promise for further development of theranostic radiopharmaceuticals.

Stable, Site-Specific ADC Conjugation with SMARTag® Technology and Innovative Linker

Antibody-drug conjugates have achieved commercial success over the last 10 years with 15 therapies launched globally to date, including 11 with U.S. FDA approval, and two biosimilars. With their ability to direct highly potent cytotoxic payloads selectively to target cells, ADCs offer the prospect of more precise treatments and a reduction in off-target effects.

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.

Targeting Ultrasmall Gold Nanoparticles with cRGD Peptide Increases the Uptake and Efficacy of Cytotoxic Payload.

Cyclic arginyl-glycyl-aspartic acid peptide (cRGD) peptides show a high affinity towards αVβ3 integrin, a receptor overexpressed in many cancers. We aimed to combine the versatility of ultrasmall gold nanoparticles (usGNP) with the target selectivity of cRGD peptide for the directed delivery of a cytotoxic payload in a novel design. usGNPs were synthesized with a modified Brust-Schiffrin method and functionalized via amide coupling and ligand exchange and their uptake, intracellular trafficking, and toxicity were characterized. Our cRGD functionalized usGNPs demonstrated increased cellular uptake by αVβ3 integrin expressing cells, are internalized via clathrin-dependent endocytosis, accumulated in the lysosomes, and when loaded with mertansine led to increased cytotoxicity. Targeting via cRGD functionalization provides a mechanism to improve the efficacy, tolerability, and retention of therapeutic GNPs.

Tub-010, a Novel Antibody-Drug-Conjugate with Reduced Nonspecific Toxicity Profile Based on Tub-Tag Technology Widens the Therapeutic Window for the Treatment of CD30+ Malignancies

Introduction: Patients with R/R CD30+ malignancies such as PTCL, CTCL and cHL often lack effective and tolerable therapy options. Available treatments frequently provide only short-term disease control at the cost of significant or cumulative toxicities. Brentuximab-Vedotin (BV, Adcetris®), an MMAE-delivering anti-CD30-ADC, has a high response rate but dose-limiting AEs often result in premature dose reduction or even therapy discontinuation. The maleimide chemistry results in a heterogeneous product (DAR 0-8) with varying PK and potency properties and spontaneous deconjugation can cause premature transfer of linker payload to serum proteins and thereby reduce the tumor selectivity. In consequence, some of the BV-induced toxicity is likely design-based leading to CD30-independent cellular uptake and aggregation of the ADC. Objectives: We aimed to generate a novel CD30-ADC with improved biophysical properties to widen the therapeutic window using Tub-tag-conjugation technology. Material & methods: TUB-010 is a next-generation ADC, implementing a novel conjugation strategy, called Tub-tag® conjugation (Schumacher, Angewandte Chemie 2015). The recombinant Tub-tag sequence, a 14 amino acid peptide derived from α-tubulin and fused to the C-termini of the CD30 mAb light chains, has unique features in that it provides a significant degree of hydrophilicity to counterbalance the payload-derived hydrophobicity, thus enabling superior biophysical properties and product homogeneity. This new technology was used to generate a DAR2-ADC with stably linked MMAE via a Cathepsin B cleavable linker (vc-PAB) and chemoenzymatic conjugation of linker payload using Tubulin-tyrosine ligase (TTL). The resulting ADC was tested for physicochemical properties, homogeneity, stability, internalization, preclinical efficacy, nonspecific uptake and general cytotoxicity in primary cells, cell lines, rats & cynomolgus monkeys. Results: Tub-tag technology enabled us to create a DAR2 anti-CD30-ADC with a binding affinity, internalization and lysosomal release characteristics similar to BV. In contrast to BV, TUB-010 is a homogeneous DAR2 ADC. The linker-payload is chemically stably attached to the mAb with neglectable premature deconjugation while in circulation, whereas protease-mediated release of MMAE within the lysosome occurs normally as expected with the vc-PAB linker. The increased ADC stability prior to internalization via CD30 leads to reduced nonspecific transfer of linker-payload to serum proteins, and overall improved PK parameters in rats. The hydrophobicity of MMAE is counterbalanced by hydrophilicity provided by the Tub-tag peptides, which resulted in > 5-fold reduced ADC aggregation under stress conditions compared to BV. The increased hydrophilicity of the overall ADC reduced nonspecific cellular uptake and consecutive cellular toxicity vs BV within the clinically therapeutic range by factor 2- to >10-fold in various human primary cells (Fig. A). When normalized to the MMAE concentration, TUB-010 showed similar in vitro cytotoxic efficacy as well as similar bystander activity compared to BV on established cancer cell lines from cHL, PTCL and CTCL patients with various levels of CD30 expression (Fig. A). In vivo, TUB-010 exerted significantly improved tumor control compared to BV when both ADCs were dosed at equal MMAE concentration in the Karpas-299 cell-derived ALCL xenograft model (Fig. B). In cynomolgus monkey dose range finding and GLP toxicity studies, TUB-010 administered 2 or 4 times Q3W in a dose range of 6-15 mg/kg showed a 5-fold widened therapeutic window for the ADC as the MTD was not reached. Hematological toxicity was reduced compared to BV and no signs of anatomical of functional tissue damage were detectable. Conclusions: Tub-tag technology allows the reduction of nonspecific target-independent toxicity of ADCs in preclinical models by improving key design issues in current ADCs such as stability and overall biophysical features. TUB-010 is a promising, novel and potential best-in-class CD30-ADC which can deliver the cytotoxic payload to CD30+ malignancies with higher precision and with a wider therapeutic window than BV. These features suggest that TUB-010 may increase the clinical benefit with CD30-targeting ADC therapy for patients with CD30+ malignancies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract C035: Biotherapeutic strategies targeting the CXCR2 axis for depletion of myeloid-derived suppressor cells in pancreatic ductal adenocarcinoma

Abstract Pancreatic Ductal Adenocarcinoma (PDAC) has a 5-year survival rate of only 10%, and limited treatment options exist. Immune checkpoint inhibitors are effective in a variety of cancer types; however, the complex immunosuppressive tumor microenvironment (TME) of PDAC is a significant barrier to immunotherapy. Myeloid-derived suppressor cells (MDSCs) are abundant in PDAC tumors from humans and mouse models. MDSCs suppress effector T cell function, leading us to hypothesize that targeting tumor MDSCs would be an effective therapeutic strategy for PDAC and enhance the efficacy of T cell-based immunotherapy. Our preliminary data and the work from others shows that CXCR2 ligands such as CXCL8/IL-8, CXCL5/ENA78, and CXCL1/GROα are the most abundant soluble factors secreted by PDAC cells. CXCR2 ligands are critical for the homing of myeloid cells to sites of injury in cutaneous wound healing, suggesting that dysregulated secretion of CXCR2 chemokines in PDAC may mimic a wound healing response that attracts myeloid cells and promotes the expansion of MDSCs and an immunosuppressive TME. To test this hypothesis, we have designed multiple biotherapeutic molecules that exploit CXCL5/ENA78 and CXCL1/GROa to target and eliminate MDSCs from PDAC tumors. Specifically, we have generated Pseudomonas aeruginosa exotoxin (ExoA) and IgG-Fc fusion proteins that will be used to deliver cytotoxic payloads to MDSCs. A variety of CXCR2 knockout and knock-in models will be used to demonstrate CXCR2 dependence and elimination of MDSCs in vitro. In vivo, we are utilizing the KPC (LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre) mouse model of PDAC, which we've shown in preliminary studies to, like human PDAC, support an abundance of MDSCs in tumors as well as secondary lymphoid organs such as the spleen. We anticipate that this study will demonstrate the therapeutic potential and actionability of targeting MDSCs and will provide novel biotherapeutic drug candidates that will ultimately improve immunotherapy outcomes in patients with PDAC. Citation Format: Ben N. Christopher, Reeder Robinson, Leticia Reyes, Lena Golick, Ashton Basar, Nathan Dolloff. Biotherapeutic strategies targeting the CXCR2 axis for depletion of myeloid-derived suppressor cells in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C035.

Antibody-Antimicrobial Conjugates for Combating Antibiotic Resistance.

As the development of new antibiotics lags far behind the emergence of drug-resistant bacteria, alternative strategies to resolve this dilemma are urgently required. Antibody-drug conjugate is a promising therapeutic platform to delivering cytotoxic payloads precisely to target cells for efficient disease treatment. Antibody-antimicrobial conjugates (AACs) have recently attracted considerable interest from researchers as they can target bacteria in the target sites and improve the effectiveness of drugs (i.e., reduced drug dosage and adverse effects), abating the upsurge of antimicrobial resistance. In this review, the selection and progress of three essential blocks that compose the AACs: antibodies, antimicrobial payloads, and linkers are discussed. The commonly used conjugation strategies and the latest applications of AACs in recent years are also summarized. The challenges and opportunities of this booming technology are also discussed at the end of this review.

The Landscape of Nucleic-Acid-Based Aptamers for Treatment of Hematologic Malignancies: Challenges and Future Directions.

Hematologic malignancies, including leukemia, lymphoma, myeloproliferative disorder and plasma cell neoplasia, are genetically heterogeneous and characterized by an uncontrolled proliferation of their corresponding cell lineages in the bone marrow, peripheral blood, tissues or plasma. Although there are many types of therapeutic drugs (e.g., TKIs, chemotherapy drugs) available for treatment of different malignancies, the relapse, drug resistance and severe side effects due to the lack of selectivity seriously limit their clinical application. Currently, although antibody-drug conjugates have been well established as able to target and deliver highly potent chemotherapy agents into cancer cells for the reduction of damage to healthy cells and have achieved success in leukemia treatment, they still also have shortcomings such as high cost, high immunogenicity and low stability. Aptamers are ssDNA or RNA oligonucleotides that can also precisely deliver therapeutic agents into cancer cells through specifically recognizing the membrane protein on cancer cells, which is similar to the capabilities of monoclonal antibodies. Aptamers exhibit higher binding affinity, lower immunogenicity and higher thermal stability than antibodies. Therefore, in this review we comprehensively describe recent advances in the development of aptamer-drug conjugates (ApDCs) with cytotoxic payload through chemical linkers or direct incorporation, as well as further introduce the latest promising aptamers-based therapeutic strategies such as aptamer-T cell therapy and aptamer-PROTAC, clarifying their bright application, development direction and challenges in the treatment of hematologic malignancies.

Phase 1 multicenter, dose-expansion study of ARX788 as monotherapy in HER2-positive advanced gastric and gastroesophageal junction adenocarcinoma

ARX788 is an anti-human epidermal growth factor receptor 2 (HER2) antibody-drug conjugate with AS269 as cytotoxic payload. In this phase 1 multicenter dose-expansion clinical trial, patients with HER2-positive advanced gastric/gastroesophageal junction adenocarcinoma failing to respond to prior trastuzumab-based standard treatment were enrolled. Between July 15th, 2019, and March 14th, 2022, 30 participants were enrolled. Twenty-eight (93.3%) patients experienced at least one drug-related adverse event (AE) and 13.3% experienced grade 3 ARX788-related AEs. The confirmed objective response rate is 37.9% (95% confidence interval [CI]: 20.7%-57.7%) and the disease control rate is 55.2% (95% CI: 35.7%-73.6%). With a median follow up of 10months, the median progression-free survival and overall survival are 4.1 (95% CI: 1.4-6.4) and 10.7months (95% CI: 4.8-not reached), respectively. The median duration of response is 8.4 (95% CI: 2.1-18.9) months. ARX788 is well tolerated and has promising anti-tumor activity in patients with HER2-positive advanced gastric adenocarcinoma (ChinaDrugTrials.org.cn: CTR20190639).

Targeting fibroblast growth factor (FGF)-inducible 14 (Fn14) for tumor therapy.

Fibroblast growth factor-inducible 14 (Fn14) is a member of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF) and is activated by its ligand TNF-like weak inducer of apoptosis (TWEAK). The latter occurs as a homotrimeric molecule in a soluble and a membrane-bound form. Soluble TWEAK (sTWEAK) activates the weakly inflammatory alternative NF-κB pathway and sensitizes for TNF-induced cell death while membrane TWEAK (memTWEAK) triggers additionally robust activation of the classical NF-κB pathway and various MAP kinase cascades. Fn14 expression is limited in adult organisms but becomes strongly induced in non-hematopoietic cells by a variety of growth factors, cytokines and physical stressors (e.g., hypoxia, irradiation). Since all these Fn14-inducing factors are frequently also present in the tumor microenvironment, Fn14 is regularly found to be expressed by non-hematopoietic cells of the tumor microenvironment and most solid tumor cells. In general, there are three possibilities how the tumor-Fn14 linkage could be taken into consideration for tumor therapy. First, by exploitation of the cancer associated expression of Fn14 to direct cytotoxic activities (antibody-dependent cell-mediated cytotoxicity (ADCC), cytotoxic payloads, CAR T-cells) to the tumor, second by blockade of potential protumoral activities of the TWEAK/Fn14 system, and third, by stimulation of Fn14 which not only triggers proinflammtory activities but also sensitizes cells for apoptotic and necroptotic cell death. Based on a brief description of the biology of the TWEAK/Fn14 system and Fn14 signaling, we discuss the features of the most relevant Fn14-targeting biologicals and review the preclinical data obtained with these reagents. In particular, we address problems and limitations which became evident in the preclinical studies with Fn14-targeting biologicals and debate possibilities how they could be overcome.

Discovery of BT8009: A Nectin-4 Targeting Bicycle Toxin Conjugate for the Treatment of Cancer.

Bicycle toxin conjugates (BTCs) are a promising new class of molecules for targeted delivery of toxin payloads into tumors. Herein we describe the discovery of BT8009, a Nectin-4 targeting BTC currently under clinical evaluation. Nectin-4 is overexpressed in multiple tumor types and is a clinically validated target for selective delivery of cytotoxic payloads. A Nectin-4 targeting bicyclic peptide was identified by phage display, which showed highly selective binding for Nectin-4 but suffered from low plasma stability and poor physicochemical properties. Multiparameter chemical optimization involving introduction of non-natural amino acids resulted in a lead Bicycle that demonstrated high affinity for Nectin-4, good stability in biological matrices, and a much-improved physicochemical profile. The optimized Bicycle was conjugated to the cytotoxin Monomethyl auristatin E via a cleavable linker to give the targeted drug conjugate BT8009, which demonstrates potent anticancer activity in in vivo rodent models.

256 (PB036) - A Phase 1 study of the anti-tissue factor antibody-drug conjugate XB002 in patients with advanced solid tumors (JEWEL-101): initial results from the dose-escalation stage

256 (PB036) - A Phase 1 study of the anti-tissue factor antibody-drug conjugate XB002 in patients with advanced solid tumors (JEWEL-101): initial results from the dose-escalation stage