A single-chain fab derived drug conjugate for HER2 specific delivery.

Despite the development of antibody-drug conjugates, the fragment Fab-based drug conjugates offer some unique capabilities in terms of safety, clearance, penetration and others. Current methods for preparing Fab drug conjugates are limited by the availability and stability of Fab proteins, leaving reports on this rare. Here, we found that a single-chain scaffold of Fab enables stabilization of the paired structure and supports high-yield expression in bacteria cytoplasm. Furthermore, we conjugated anti-neoplastic agent SN38 to the C-terminus by sortase A ligation and generated a homogenous Fab conjugate with the drug-to-Fab ratio of 1. The resulting anti-HER2 Fab-SN38 conjugate demonstrated potent and antigen-dependent cell-killing ability with the aid of its special cathepsin-triggered cyclization-promoted release mechanism. In vivo, Fab-SN38 can prevent growths of HER2-positive tumors in athymic mice and be well tolerated to the treatment at 7 mg/kg per dose. Anti-tumor activity, high dose tolerance and penetration advantage observed in this study would merit Fab conjugate investigation in target chemotherapy.

Pharmacovigilance study of the association between peripheral neuropathy and antibody-drug conjugates using the FDA adverse event reporting system.

Antibody-drug conjugates (ADCs) are among the fastest-growing classes of anticancer drugs, making it crucial to evaluate their potential for causing peripheral neuropathy. We analyzed data from the FAERS database (January 1, 2014, to June 30, 2023) using disproportionality and Bayesian methods. We identified 3076 cases of ADC-associated peripheral neuropathy. Our study revealed significant signals for all ADCs (ROR 1.82, 95% CI 1.76-1.89). ADCs with tubulin-binding payloads showed significant peripheral neuropathy signals (ROR 2.31, 95% CI 2.23-2.40), whereas those with DNA-targeting (ROR 0.48, 95% CI 0.39-0.59) and topoisomerase 1 inhibitor (ROR 0.56, 95% CI 0.48-0.66) payloads exhibited non-significant signals. Signals for peripheral sensory neuropathy were 4.83, 2.44, 2.74, and 2.21 (calculated based on IC025) for brentuximab vedotin, trastuzumab emtansine, enfortumab vedotin, and polatuzumab vedotin, while signals for peripheral motor neuropathy were 5.31, 0.34, 2.27, and 0.03, respectively. The median time to onset for all ADCs was 127 days (interquartile range 40-457). Tisotumab vedotin had the highest hospitalization rate at 26.67%, followed by brentuximab vedotin at 25.5%. Trastuzumab emtansine had the highest mortality rate ,with 80 deaths (11.96%) among 669 cases. Based on FAERS database, only ADCs with tubulin-binding payloads exhibited significant peripheral neuropathy signals. Brentuximab vedotin and enfortumab vedotin showed similar profiles for peripheral sensory neuropathy and motor neuropathy. Given the delayed time to onset and potentially poor outcomes, ADC-related peripheral neuropathy warrants significant attention.

New Advances in Metastatic Urothelial Cancer: A Narrative Review on Recent Developments and Future Perspectives.

The standard of care for advanced or metastatic urothelial carcinoma (mUC) was historically identified with platinum-based chemotherapy. Thanks to the advances in biological and genetic knowledge and technologies, new therapeutic agents have emerged in this setting recently: the immune checkpoint inhibitors and the fibroblast growth factor receptor inhibitors as the target therapy for patients harboring alterations in the fibroblast growth factor receptor (FGFR) pathway. However, chasing a tumor's tendency to recur and progress, a new class of agents has more recently entered the scene, with promising results. Antibody-drug conjugates (ADCs) are in fact the latest addition, with enfortumab vedotin being the first to receive accelerated approval by the U.S. Food and Drug Administration in December 2019, followed by sacituzumab govitecan. Many other ADCs are still under investigation. ADCs undoubtedly represent the new frontier, with the potential of transforming the management of mUC treatment in the future. Therefore, we reviewed the landscape of mUC treatment options, giving an insight into the molecular basis and mechanisms, and evaluating new therapeutic strategies in the perspective of more and more personalized treatments.

Tuning Responses to Polatuzumab Vedotin in B-cell Lymphoma.

Polatuzumab vedotin, an antibody-drug conjugate targeting CD79B, is the first new drug approved for first-line therapy of diffuse large B-cell lymphoma in more than two decades, although factors determining treatment responses to polatuzumab vedotin remain unknown. Two new studies identified central mechanisms of lower sensitivity, namely reduced accessibility of the CD79B epitope through N-linked glycosylation of CD79B and lower CD79B surface expression levels due to the activity of the KLHL6 E3 ligase. See related article by Corcoran et al., p. 1653 (6) See related article by Meriranta et al. (7).

Post-marketing drug safety surveillance of enfortumab vedotin: an observational pharmacovigilance study based on a real-world database.

Background: Enfortumab vedotin (EV) is an antibody-drug conjugate (ADC) that has been approved by the FDA for patients with locally advanced or metastatic urothelial carcinoma (UC). This study presents a comprehensive pharmacovigilance analysis of the post-marketing safety profile of EV in the real-world based on the US Food and Drug Administration Adverse Event Reporting System (FAERS). Methods: Adverse event (AE) reports regarding EV between January 2020 and December 2023 were obtained from the FAERS database. The standardized MedDRA query (SMQ) narrow search AEs on the preferred term (PT) level were used. Disproportionality analysis was performed to identify the AE signals for EV with the reporting odds ratio (ROR), proportional reporting ratio (PRR), multi-item gamma Poisson shrinker (MGPS), and Bayesian confidence propagation neural network (BCPNN). Results: A total of 2,216 reports regarding EV were included in the present study. SMQ analysis results indicated that a stronger strength signal was found in severe cutaneous adverse reactions, retroperitoneal fibrosis, and peripheral neuropathy. A total of 116 significant disproportionality PTs referring to 14 system organ classes (SOCs) were retained by disproportionality analysis, with 49 PTs not listed on the EV drug label. Frequently reported EV-related AEs included rash, peripheral neuropathy, decreased appetite, alopecia, and pruritus. The time to onset of the majority of EV-related AEs was within 30 days (66.05%), with only 0.73% events occurring after 1 year. Conclusion: The disproportionality analysis highlights that dermatologic toxicity and peripheral neuropathy were the major AEs induced by EV. The potential AEs not listed on the drug label were mainly related to gastrointestinal, hepatic, and pulmonary events. Further research is needed to confirm and explore the EV-related AEs in clinical practice.

Imaged capillary isoelectric focusing method development for charge variants of high DAR ADCs.

BACKGROUND: Charge heterogeneity is a critical quality attribute for therapeutic biologics including antibody-drug conjugates (ADCs). Developing an ion exchange chromatography (IEX) or an imaged capillary isoelectric focusing (icIEF) method for ADCs with high drug-to-antibody ratio (DAR) is challenging because of the increased hydrophobicity from the payload-linker, DAR heterogeneity, and payload-linker instability. A sub-optimal method can be poorly stability-indicating due to the inability to discern contributions from charge and size variants conjugated with different number of drugs/payloads. Systematic strategy and guidance on charge variant method development is highly desired for high DAR ADCs with various complex structures. RESULTS: This work encompasses the development and optimization of icIEF methods for high DAR ADCs of various DAR values (4-8) and payload linker chemistry. Method optimization focuses on improving resolution and stability indicating capabilities and differentiating contributions from the protein and payload-linker. Types, proportion, and combination of solubilizers and carrier ampholytes, as well as focusing parameters were interrogated. Our findings show that the structural units of the linker, the DAR, and the payload chemistry prescribe the selection of buffer, solubilizer, and ampholyte. We demonstrate that a stronger denaturant or solubilizer is needed for high DAR ADCs with polyethylene glycol (PEG)-containing linker structure compared to peptide linker. For unstable payload-linker, buffer system enhances sample stability which is vital to method robustness. In addition, a longer isoelectric focusing time is necessary for an ADC than its corresponding antibody to reach optimal focusing. SIGNIFICANCE: To the best of our knowledge, this is the first comprehensive study on icIEF method development for charge variant determination of high DAR ADCs with unique physicochemical properties.

Structure-Activity Relationship of Antibody-Oligonucleotide Conjugates: Evaluating Bioconjugation Strategies for Antibody-Phosphorodiamidate Morpholino Oligomer Conjugates for Drug Development.

Antibody-oligonucleotide conjugates (AOCs) are promising treatments for Duchenne muscular dystrophy (DMD). They work via induction of exon skipping and restoration of dystrophin protein in skeletal and heart muscles. The structure-activity relationships (SARs) of AOCs comprising antibody-phosphorodiamidate morpholino oligomers (PMOs) depend on several aspects of their component parts. We evaluate the SAR of antimouse transferrin receptor 1 antibody (αmTfR1)-PMO conjugates: cleavable and noncleavable linkers, linker location on the PMO, and the impact of drug-to-antibody ratios (DARs) on plasma pharmacokinetics (PK), oligonucleotide delivery to tissues, and exon skipping. AOCs containing a stable linker with a DAR9.7 were the most effective PMO delivery vehicles in preclinical studies. We demonstrate that αmTfR1-PMO conjugates induce dystrophin protein restoration in the skeletal and heart muscles of mdx mice. Our results show that αmTfR1-PMO conjugates are a potentially effective approach for the treatment of DMD.

Design and Optimization of Selectivity-Tunable Toll-like Receptor 7/8 Agonists as Novel Antibody-Drug Conjugate Payloads.

Toll-like receptors 7 and 8 are involved in modulating the adaptive and innate immune responses, and their activation has shown promise as a therapeutic strategy in the field of immuno-oncology. While systemic exposure to TLR7/8 agonists can result in poor tolerance, combination therapies and targeted delivery through antibody-drug conjugates (ADCs) can help mitigate adverse effects. Described herein is the identification of a novel and potent series of pyrazolopyrimidine-based TLR7/8 agonists with tunable receptor selectivity. Representative agonists from this series were successfully able to induce the production of various proinflammatory cytokines and chemokines from human peripheral blood mononuclear cells. Anti-HER2-25 and anti-HER2-26 ADCs made from this class of payloads demonstrated mechanism-based activation of TLR7/8 in a THP1/N87 coculture system.

[Basics and Innovations in Antibody-Drug Conjugates].

The efficacy of antibody-drug conjugates(ADCs)has been well-established in clinical use, prompting ongoing research and development efforts to advance the field of ADCs further. This chapter provides overview of the structure and mechanism of action of ADCs, detailing the roles of its components: the antibody, the payload, and the linker. ADCs leak from cancer vessels to bind to specific antigens on the surface of tumor cells. Upon binding and internalization, the drug is released by metabolic enzymes, such as peptidases in the lysosome. The therapeutic window of the conjugated drug is therefore expanded. To enhance the efficacy of ADCs, the chapter will also explore the development of methodologies for generating homogeneous ADCs and the concept of bystander effects, which are particularly relevant in the tumor microenvironment. Additionally, innovative approaches such as radioimmunotherapy, utilizing alpha-ray emitting radionuclides, and photoimmunotherapy, are discussed as promising next-generation ADC strategies. The integration of ADCs with immunotherapy may offer amplified effectiveness through synergistic actions. The chapter underscores that the prolonged therapeutic impact of ADCs cannot be solely attributed to the targeted delivery and controlled release of the payload. A comprehensive understanding from the perspective of cancer immunology is imperative for elucidating the underlying mechanisms contributing to their sustained efficacy.

Structure-Activity Relationship of Antibody-Oligonucleotide Conjugates: Evaluating Bioconjugation Strategies for Antibody-siRNA Conjugates for Drug Development.

Antibody-oligonucleotide conjugates are a promising class of therapeutics for extrahepatic delivery of small interfering ribonucleic acids (siRNAs). These conjugates can be optimized for improved delivery and mRNA knockdown (KD) through understanding of structure-activity relationships. In this study, we systematically examined factors including antibody isotype, siRNA chemistry, linkers, conjugation chemistry, PEGylation, and drug-to-antibody ratios (DARs) for their impact on bioconjugation, pharmacokinetics (PK), siRNA delivery, and bioactivity. Conjugation site (cysteine, lysine, and Asn297 glycan) and DAR proved critical for optimal conjugate PK and siRNA delivery. SiRNA chemistry including 2' sugar modifications and positioning of phosphorothioates were found to be critical for delivery and duration of action. By utilizing cleavable and noncleavable linkers, we demonstrated the impact of linkers on PK and mRNA KD. To achieve optimal properties of antibody-siRNA conjugates, a careful selection of siRNA chemistry, DAR, conjugation sites, linkers, and antibody isotype is necessary.

[Antibody-Drug Conjugates in Breast Cancer and Gynecologic Cancer].

Antibody-drug conjugates(ADCs)have become widely used in the treatment of various malignancies over the past 15 years. In breast cancer, T-DM1 and T-DXd which is HER2-targeted ADC have been approved and are broadly used in Japan. Sacituzumab govitecan, TROP2-ADC has been approved in US. Hence, multiple ADCs could be used for breast cancer treatment. In gynecological cancers, tisotumab vedotin for cervical cancer and mirvetuximab soravtansine for ovarian cancer have been approved in the US. Optimizing treatment sequences and overcoming resistance mechanisms for ADC are important challenges in the situations where multiple ADCs are available. The current development landscape suggests further enhancement of ADC treatment efficacy through new targets, novel payloads, bispecific ADCs, and combination therapies with immunotherapy. This article outlines the current status of ADCs in breast and gynecological cancers, highlighting ongoing development and challenges emerging in the field.

Novel immunotherapeutics against LGR5 to target multiple cancer types.

We have developed and validated a highly specific, versatile antibody to the extracellular domain of human LGR5 (α-LGR5). α-LGR5 detects LGR5 overexpression in >90% of colorectal cancer (CRC), hepatocellular carcinoma (HCC) and pre-B-ALL tumour cells and was used to generate an Antibody-Drug Conjugate (α-LGR5-ADC), Bispecific T-cell Engager (α-LGR5-BiTE) and Chimeric Antigen Receptor (α-LGR5-CAR). α-LGR5-ADC was the most effective modality for targeting LGR5+ cancer cells in vitro and demonstrated potent anti-tumour efficacy in a murine model of human NALM6 pre-B-ALL driving tumour attrition to less than 1% of control treatment. α-LGR5-BiTE treatment was less effective in the pre-B-ALL cancer model yet promoted a twofold reduction in tumour burden. α-LGR5-CAR-T cells also showed specific and potent LGR5+ cancer cell killing in vitro and effective tumour targeting with a fourfold decrease in pre-B-ALL tumour burden relative to controls. Taken together, we show that α-LGR5 can not only be used as a research tool and a biomarker but also provides a versatile building block for a highly effective immune therapeutic portfolio targeting a range of LGR5-expressing cancer cells.

Clinical best practices in interdisciplinary management of human epidermal growth factor receptor 2 antibody-drug conjugates-induced interstitial lung disease/pneumonitis: An expert consensus in China.

Antibody-drug conjugates (ADCs) have demonstrated effectiveness in treating various cancers, particularly exhibiting specificity in targeting human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Recent advancements in phase 3 clinical trials have broadened current understanding of ADCs, especially trastuzumab deruxtecan, in treating other HER2-expressing malignancies. This expansion of knowledge has led to the US Food and Drug Administration's approval of trastuzumab deruxtecan for HER2-positive and HER2-low breast cancer, HER2-positive gastric cancer, and HER2-mutant nonsmall cell lung cancer. Concurrent with the increasing use of ADCs in oncology, there is growing concern among health care professionals regarding the rise in the incidence of interstitial lung disease or pneumonitis (ILD/p), which is associated with anti-HER2 ADC therapy. Studies on anti-HER2 ADCs have reported varying ILD/p mortality rates. Consequently, it is crucial to establish guidelines for the diagnosis and management of ILD/p in patients receiving anti-HER2 ADC therapy. To this end, a panel of Chinese experts was convened to formulate a strategic approach for the identification and management of ILD/p in patients treated with anti-HER2 ADC therapy. This report presents the expert panel's opinions and recommendations, which are intended to guide the management of ILD/p induced by anti-HER2 ADC therapy in clinical practice.

HER2 exon 20 mutant non-small cell lung cancer with complete remission of intracranial metastases with trastuzumab deruxtecan: a case report.

Trastuzumab deruxtecan (T-DXd) is a novel anti-HER2 antibody-drug conjugate formed by the combination of trastuzumab and deruxtecan. It is used in human epidermal growth factor 2 receptor (HER2) mutant breast, stomach and colorectal cancers as well as non-small cell lung cancer (NSCLC). The 58-year-old denovo metastatic NSCLC patient we will discuss here progressed with newly developing brain metastasis under first-line carboplatin/paclitaxel treatment. After next generation sequencing revealed a mutation in the ERBB2 gene located in exon 20, we administered T-DXd to our patient. While a significant improvement was observed in the clinical condition of the patient after one course of treatment, brain metastases were found to be in complete response in control screening after four courses of treatment. Systemic screening with PET/computed tomography showed nearly complete regression of the primary lesion, metastatic lymphadenopathies, and surrenal metastases. T-DXd may be successfully used in HER2 mutant metastatic NSCLC patients. In addition, it can also be successfully used in patients with central nervous system metastases with or without cranial radiotherapy.

Discovery of a novel highly specific, fully human PSCA antibody and its application as an antibody-drug conjugate in prostate cancer.

Prostate stem cell antigen (PSCA) is expressed in all stages of prostate cancer, including in advanced androgen-independent tumors and bone metastasis. PSCA may associate with prostate carcinogenesis and lineage plasticity in prostate cancer. PSCA is also a promising theranostic marker for a variety of other solid tumors, including pancreatic adenocarcinoma and renal cell carcinoma. Here, we identified a novel fully human PSCA antibody using phage display methodology. The structure-based affinity maturation yielded a high-affinity binder, F12, which is highly specific and does not bind to 6,000 human membrane proteins based on a membrane proteome array assay. F12 targets PSCA amino acids 63-69 as tested by the peptide scanning microarray, and it cross-reacts with the murine PSCA. IgG1 F12 efficiently internalizes into PSCA-expressing tumor cells. The antimitotic reagent monomethyl auristatin E (MMAE)-conjugated IgG1 F12 (ADC, F12-MMAE) exhibits dose-dependent efficacy and specificity in a human prostate cancer PC-3-PSCA xenograft NSG mouse model. This is a first reported ADC based on a fully human PSCA antibody and MMAE that is characterized in a xenograft murine model, which warrants further optimizations and investigations in additional preclinical tumor models, including prostate and other solid tumors.

Sacituzumab Govitecan in patients with breast cancer brain metastases and recurrent glioblastoma: a phase 0 window-of-opportunity trial.

Sacituzumab Govitecan (SG) is an antibody-drug conjugate that has demonstrated efficacy in patients with TROP-2 expressing epithelial cancers. In a xenograft model of intracranial breast cancer, SG inhibited tumor growth and increased mouse survival. We conducted a prospective window-of-opportunity trial (NCT03995706) at the University of Texas Health Science Center at San Antonio to examine the intra-tumoral concentrations and intracranial activity of SG in patients undergoing craniotomy for breast cancer with brain metastases (BCBM) or recurrent glioblastoma (rGBM). We enrolled 25 patients aged ≥18 years diagnosed with BCBM and rGBM to receive a single intravenous dose of SG at 10 mg/kg given one day before resection and continued on days 1 and 8 of 21-day cycles following recovery. The PFS was 8 months and 2 months for BCBM and rGBM cohorts, respectively. The OS was 35.2 months and 9.5 months, respectively. Grade≥3 AE included neutropenia (28%), hypokalemia (8%), seizure (8%), thromboembolic event (8%), urinary tract infection (8%) and muscle weakness of the lower limb (8%). In post-surgical tissue, the median total SN-38 was 249.8 ng/g for BCBM and 104.5 ng/g for rGBM, thus fulfilling the primary endpoint. Biomarker analysis suggests delivery of payload by direct release at target site and that hypoxic changes do not drive indirect release. Secondary endpoint of OS was 35.2 months for the BCBM cohort and 9.5 months for rGBM. Non-planned exploratory endpoint of ORR was 38% for BCBM and 29%, respectively. Exploratory endpoint of Trop-2 expression was observed in 100% of BCBM and 78% of rGBM tumors. In conclusion, SG was found to be well tolerated with adequate penetration into intracranial tumors and promising preliminary activity within the CNS. Trial Registration: Trial (NCT03995706) enrolled at Clinical Trials.gov as Neuro/Sacituzumab Govitecan/Breast Brain Metastasis/Glioblastoma/Ph 0: https://clinicaltrials.gov/study/NCT03995706?cond=NCT03995706 .

A New Age of Drug Delivery: A Comparative Perspective of Ferritin-Drug Conjugates (FDCs) and Antibody-Drug Conjugates (ADCs).

Ferritin-drug conjugates (FDCs) and antibody-drug conjugates (ADCs) respectively represent the innovative and traditional mainstream approaches in drug delivery systems, each offering unique advantages and challenges. This viewpoint delves into the evolving landscape of drug delivery technologies, specifically focusing on FDCs and ADCs. Each method exhibits unique advantages and inherent challenges, shaping their roles in therapeutic applications. The article provides a comparative analysis of two delivery systems, FDCs and ADCs, in terms of targeting accuracy, drug loading capacity, and the nature of the payload itself. This comparison offers valuable insights into the distinct advantages and disadvantages associated with each system, enabling a clearer understanding of their potential applications and limitations in therapeutic contexts. This analysis is crucial for optimizing the use of these delivery systems across varying medical contexts, offering a comprehensive overview of their impact on the field of drug delivery.

UGT1A1*28 polymorphism and the risk of toxicity and disease progression in patients with breast cancer receiving sacituzumab govitecan.

BACKGROUND: Sacituzumab govitecan (sacituzumab) emerged as an important agent in metastatic and locally recurrent HER2-negative breast cancer treatment. UGT1A1 polymorphisms have also been shown to predict sacituzumab toxicity. METHODS: In this retrospective study, we sought to evaluate the associations between UGT1A1 status, toxicity, and therapeutic outcomes in sacituzumab recipients with advanced breast cancer who underwent genotype testing for UGT1A1 alleles (N = 68). RESULTS: We found 17 (25%) of our patients to be homozygous for UGT1A1*28 and 24 (35.3%) were heterozygous. Of seven African American patients with triple-negative breast cancer, five were homozygous for UGT1A1*28 and two were heterozygous. Patients with a homozygous UGT1A1*28 genotype were significantly more likely to have treatment terminated because of adverse effects. However, the polymorphism was not associated with treatment discontinuation because of disease progression. CONCLUSION: This retrospective, real-world analysis suggests potential clinical utility in UGT1A1 testing for patients receiving sacituzumab, but future trials are needed to confirm the association between genotypes and treatment outcomes.

Sacituzumab Govitecan Demonstrates Efficacy across Tumor Trop-2 Expression Levels in Patients with Advanced Urothelial Cancer.

PURPOSE: Human trophoblast cell surface antigen 2 (Trop-2) is a protein highly expressed in urothelial cancer (UC). Sacituzumab govitecan (SG) is a Trop-2-directed antibody drug conjugate with a hydrolysable linker and a potent SN-38 payload. This study explored Trop-2 expression in tumors treated with SG in cohorts 1 to 3 (C1-3) from the TROPHY-U-01 study and evaluated whether efficacy was associated with Trop-2 expression. PATIENTS AND METHODS: TROPHY-U-01 (NCT03547973) is an open-label phase II study that assessed the efficacy and safety of SG (alone or in combinations) in patients with unresectable locally advanced or metastatic UC (mUC). Archival tumor samples collected at enrollment for C1-3 were analyzed for Trop-2 membrane expression by considering histological scores (H-scores; scale 0-300) and the percentage of membrane positive tumor cells at low magnification (4×). The association of Trop-2 with clinical endpoints [objective response rate (ORR), progression-free survival (PFS), and overall survival (OS)] was evaluated. RESULTS: In C1-3, tissue was collected from 158 (82%) of 192 treated patients, and 146 (76%) had evaluable Trop-2 data. Trop-2 was highly expressed in tumor samples. The median [interquartile range (IQR)] Trop-2 H-score was 215 (180-246), and the median (IQR) percentage of membrane positive tumor cells was 91% (80-98). Trop-2 expression at any level was observed in 98% of patients. Furthermore, ORR, PFS, and OS benefits were observed across all Trop-2 expression levels. CONCLUSIONS: Trop-2 protein is highly expressed in UC, as confirmed by examining tumors from patients enrolled in the TROPHY-U-01 trial. The results indicate that SG demonstrates efficacy in mUC across Trop-2 expression levels.