A Multifunctional Neutralizing Antibody-Conjugated Nanoparticle Inhibits and Inactivates SARS-CoV-2.

The outbreak of 2019 coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global pandemic. Despite intensive research, the current treatment options show limited curative efficacies. Here the authors report a strategy incorporating neutralizing antibodies conjugated to the surface of a photothermal nanoparticle (NP) to capture and inactivate SARS-CoV-2. The NP is comprised of a semiconducting polymer core and a biocompatible polyethylene glycol surface decorated with high-affinity neutralizing antibodies. The multifunctional NP efficiently captures SARS-CoV-2 pseudovirions and completely blocks viral infection to host cells in vitro through the surface neutralizing antibodies. In addition to virus capture and blocking function, the NP also possesses photothermal function to generate heat following irradiation for inactivation of virus. Importantly, the NPs described herein significantly outperform neutralizing antibodies at treating authentic SARS-CoV-2 infection in vivo. This multifunctional NP provides a flexible platform that can be readily adapted to other SARS-CoV-2 antibodies and extended to novel therapeutic proteins, thus it is expected to provide a broad range of protection against original SARS-CoV-2 and its variants.

Assay format diversity in pre-clinical immunogenicity risk assessment: Toward a possible harmonization of antigenicity assays.

A major impediment to successful use of therapeutic protein drugs is their ability to induce anti-drug antibodies (ADA) that can alter treatment efficacy and safety in a significant number of patients. To this aim, in silico, in vitro, and in vivo tools have been developed to assess sequence and other liabilities contributing to ADA development at different stages of the immune response. However, variability exists between similar assays developed by different investigators due to the complexity of assays, a degree of uncertainty about the underlying science, and their intended use. The impact of protocol variations on the outcome of the assays, i.e., on the immunogenicity risk assigned to a given drug candidate, cannot always be precisely assessed. Here, the Non-Clinical Immunogenicity Risk Assessment working group of the European Immunogenicity Platform (EIP) reviews currently used assays and protocols and discusses feasibility and next steps toward harmonization and standardization.

Switchable CAR-T Cells Outperformed Traditional Antibody-Redirected Therapeutics Targeting Breast Cancers.

Various antibody-redirected immunotherapeutic approaches, including antibody-drug conjugates (ADCs), bispecific antibodies (bsAbs), and chimeric antigen receptor-T (CAR-T) cells, have been devised to produce specific activity against various cancer types. Using genetically encoded unnatural amino acids, we generated a homogeneous Her2-targeted ADC, a T cell-redirected bsAb, and a FITC-modified antibody capable of redirecting anti-FITC CAR-T (switchable CAR-T; sCAR-T) cells to target different Her2-expressing breast cancers. sCAR-T cells showed activity against Her2-expressing tumor cells comparable to that of conventional anti-Her2 CAR-T cells and superior to that of ADC- and bsAb-based approaches. To prevent antigen escape, we designed bispecific sCAR-T cells targeting both the Her2 receptor and IGF1R, which showed an overall improved activity against cancer cells with low Her2 expression. This study increases our understanding of various explored cancer therapeutics and underscores the efficient application of sCAR-T cells as a promising therapeutic option for breast cancer patients with low or heterogeneous antigen expression.

Generation and testing of engineered multimeric Fabs of trastuzumab.

Recombinant antibodies fragments in several new formats are routinely investigated and used in diagnostic and therapeutic applications as anti-cancers molecules. New antibody formats are generated to compensate the need for multispecificity and site-specific introduction of fluorescent dyes, cytotoxic payloads or for generating semisynthetic multimeric molecules. Fabs of trastuzumab bearing transglutaminase (MTG) reactive sites were generated by periplasmic expression in E. coli and purified. Multimeric Fabs were generated by either disulfide bridge formation or by using MTG-sensitive peptide linkers. Binding to receptor was assessed by ELISA and SPR methods. Internalization and growth inhibition assays were performed on BT-474 and SKBR3 Her2+ cells. Fabs were successfully produced and dimerized or trimerized using MTG and suitably designed peptide linkers. Site-specific derivatizations with fluorophores were similarly achieved. The monomeric, dimeric and trimeric variants bind the receptor with affinities similar or superior to the full antibody. Fab and Fab2 are rapidly internalized in Her2+ cells and exhibit growth inhibition abilities similar to the full antibody. Altogether, the data show that the recombinant Fabs can be produced in E. coli and converted into multimeric variants by MTG-based bioconjugation. Similar approaches are extendable to the introduction of cytotoxic payloads for the generation of novel Antibody Drug Conjugates.

Thermostability detection and optimization of glycoengineered antibodies and antibody-drug conjugates based on differential scanning flouremitry analysis.

Thermostability of monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs), as a critical property of biotherapeutics, is important for their physicochemical processes, pharmacodynamics, and pharmacokinetics. Fc glycosylation of mAbs plays a crucial role in antibody functions including thermostability, however, due to the lack of homogeneous glycosylation for comparison, the precise impact of glycoforms on thermostability of mAbs and ADCs remains challenging to elucidate. In this paper, we employed the technique of differential scanning fluorimetry (DSF) to investigate the thermostability of Fc domains, glycoengineered mAbs, and ADCs, carrying well-defined N-glycan structures for comparison. The results revealed that high-mannose-type N-glycans dramatically reduce the Tm value of Fc, compared to complex-type N-glycans. We also found that core-fucose contributes to the thermostability of mAbs, and the unnatural modification on non-reducing end of biantennary N-glycan can compensate the reduced stability of afucosylated mAbs and maintain the advantage of enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). DSF analysis of lysine-linked and glycosite-specific ADCs indicated that thermostability of glycan-linked ADCs is reduced, but it could be improved by using an optimized linkage. This work provides an in-depth analysis on thermostability of mAbs and ADCs with homogeneous glycoforms, and also proposes new strategies for optimizing glycoengineered mAbs and glycosite-specific ADCs using unnatural glycan and stabilized linkage.

Establishment of an immunofiltration strip for the detection of 17ß-estradiol based on the photothermal effect of black phosphorescence.

Recently, the photothermal effect of nanomaterials has opened the door for new appealing strategy, which can generate a promising and powerful tool when combined with immunoassay. As a new kind of nanomaterial, black phosphorus (BP) has aroused widespread interest. In this study, a novel immunofiltration strip method with temperature as the readout signal based on the photothermal effect of BP nanosheets was established. The temperature was monitored by a portable temperature sensor. Using an indirect competitive strategy, it provides a simple, rapid, sensitive, and economic platform for the detection of 17ß-estradiol, a kind of endocrine disrupting compound that is frequently detected in environmental water or food samples. The higher the concentration of 17ß-estradiol in the sample, the less BP nanosheets are brought to bind to the strip surface, along with lower temperature variation when exposed to intensive laser irradiation. Under optimum conditions, a detection limit of 0.104 ng mL-1 was achieved. The feasibility of this assay was assessed by a standard addition method in water and milk samples, showing good performance and indicating potential application value for easy-to-use, inexpensive, and on-site monitoring of 17ß-estradiol.

Conjugation of a Small-Molecule TLR7 Agonist to Silica Nanoshells Enhances Adjuvant Activity.

Stimulation of Toll-like receptors (TLRs) and/or NOD-like receptors on immune cells initiates and directs immune responses that are essential for vaccine adjuvants. The small-molecule TLR7 agonist, imiquimod, has been approved by the FDA as an immune response modifier but is limited to topical application due to its poor pharmacokinetics that causes undesired adverse effects. Nanoparticles are increasingly used with innate immune stimulators to mitigate side effects and enhance adjuvant efficacy. In this study, a potent small-molecule TLR7 agonist, 2-methoxyethoxy-8-oxo-9-(4-carboxybenzyl)adenine (1V209), was conjugated to hollow silica nanoshells (NS). Proinflammatory cytokine (IL-6, IL-12) release by mouse bone-marrow-derived dendritic cells and human peripheral blood mononuclear cells revealed that the potency of silica nanoshells-TLR7 conjugates (NS-TLR) depends on nanoshell size and ligand coating density. Silica nanoshells of 100 nm diameter coated with a minimum of ∼6000 1V209 ligands/particle displayed 3-fold higher potency with no observed cytotoxicity when compared to an unconjugated TLR7 agonist. NS-TLR activated the TLR7-signaling pathway, triggered caspase activity, and stimulated IL-1ß release, while neither unconjugated TLR7 ligands nor silica shells alone produced IL-1ß. An in vivo murine immunization study, using the model antigen ovalbumin, demonstrated that NS-TLR increased antigen-specific IgG antibody induction by 1000× with a Th1-biased immune response, compared to unconjugated TLR7 agonists. The results show that the TLR7 ligand conjugated to silica nanoshells is capable of activating an inflammasome pathway to enhance both innate immune-stimulatory and adjuvant potencies of the TLR7 agonist, thereby broadening applications of innate immune stimulators.

Conjugation of DM1 to anti-CD30 antibody has potential antitumor activity in CD30-positive hematological malignancies with lower systemic toxicity.

An anti-CD30 antibody-drug conjugate incorporating the antimitotic agent DM1 and a stable SMCC linker, anti-CD30-MCC-DM1, was generated as a new antitumor drug candidate for CD30-positive hematological malignancies. Here, the in vitro and in vivo pharmacologic activities of anti-CD30-MCC-DM1 (also known as F0002-ADC) were evaluated and compared with ADCETRIS (brentuximab vedotin). Pharmacokinetics (PK) and the safety profiles in cynomolgus monkeys were assessed. Anti-CD30-MCC-DM1 was effective in in vitro cell death assays using CD30-positive lymphoma cell lines. We studied the properties of anti-CD30-MCC-DM1, including binding, internalization, drug release and actions. Unlike ADCETRIS, anti-CD30-MCC-DM1 did not cause a bystander effect in this study. In vivo, anti-CD30-MCC-DM1 was found to be capable of inducing tumor regression in subcutaneous inoculation of Karpas 299 (anaplastic large cell lymphoma), HH (cutaneous T-cell lymphoma) and L428 (Hodgkin's disease) cell models. The half-lives of 4 mg/kg and 12 mg/kg anti-CD30-MCC-DM1 were about 5 days in cynomolgus monkeys, and the tolerated dose was 30 mg/kg in non-human primates, supporting the tolerance of anti-CD30-MCC-DM1 in humans. These results suggest that anti-CD30-MCC-DM1 presents efficacy, safety and PK profiles that support its use as a valuable treatment for CD30-positive hematological malignancies.

Photothermal treatment with EGFRmAb-AuNPs induces apoptosis in hypopharyngeal carcinoma cells via PI3K/AKT/mTOR and DNA damage response pathways.

Hypopharyngeal carcinoma (HC) is one of the most malignant tumors in the upper aerodigestive tract. Currently, there are no effective treatments for HC. Gold nanoparticles (AuNPs) are a promising tool that can be used for plasmonic photothermal therapy (PPTT), which refers to the use of electromagnetic radiation, most often in near infrared (NIR) region, for the treatment of various medical conditions including cancer. AuNPs have been proved to be a promising tool for NIR spectroscopy-mediated photothermal therapies. In this study, we chemically conjugated AuNPs with a monoclonal antibody (mAb) targeting the epidermal growth factor receptor (EGFR), a cell-surface receptor that is overexpressed in many cancers. We then assessed the effect of NIR photothermal treatment with the EGFRmAb-AuNPs in FaDu HC cells. Our data showed that nanoparticle conjugation with the EGFRmAb improved the specific targeting towards FaDu cells and reduced cytotoxicity towards normal (293 T) cells which do not overexpress the EGFR. A significant amount of our EGFRmAb-conjugated AuNPs could enter the nucleus. Moreover, the expression levels of double strand DNA break repair proteins, including p-ATR, p-CHK1, and p-CHK2 were increased following AuNPs treatment, indicating the presence of DNA damage. These findings suggest that the AuNPs can potentially disrupt genome integrity and induce apoptosis. In addition, EGFRmAb-AuNPs+NIR could induce FaDu cell apoptosis, accompanied by the inhibition of the PI3K/AKT/mTOR pathway and stimulation of DNA damage response. Based on these data, PPTT using the EGFRmAb-AuNPs could be a new promising treatment for HC.

Near-infrared photoimmunotherapy of pancreatic cancer using an indocyanine green-labeled anti-tissue factor antibody.

AIM: To investigate near-infrared photoimmunotherapeutic effect mediated by an anti-tissue factor (TF) antibody conjugated to indocyanine green (ICG) in a pancreatic cancer model. METHODS: Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that utilizes an antibody-photosensitizer conjugate administration, followed by NIR light exposure. Anti-TF antibody 1849-ICG conjugate was synthesized by labeling of rat IgG2b anti-TF monoclonal antibody 1849 (anti-TF 1849) to a NIR photosensitizer, ICG. The expression levels of TF in two human pancreatic cancer cell lines were examined by western blotting. Specific binding of the 1849-ICG to TF-expressing BxPC-3 cells was examined by fluorescence microscopy. NIR-PIT-induced cell death was determined by cell viability imaging assay. In vivo longitudinal fluorescence imaging was used to explore the accumulation of 1849-ICG conjugate in xenograft tumors. To examine the effect of NIR-PIT, tumor-bearing mice were separated into 5 groups: (1) 100 µg of 1849-ICG i.v. administration followed by NIR light exposure (50 J/cm2) on two consecutive days (Days 1 and 2); (2) NIR light exposure (50 J/cm2) only on two consecutive days (Days 1 and 2); (3) 100 µg of 1849-ICG i.v. administration; (4) 100 µg of unlabeled anti-TF 1849 i.v. administration; and (5) the untreated control. Semiweekly tumor volume measurements, accompanied with histological and immunohistochemical (IHC) analyses of tumors, were performed 3 d after the 2nd irradiation with NIR light to monitor the effect of treatments. RESULTS: High TF expression in BxPC-3 cells was observed via western blot analysis, concordant with the observed preferential binding with intracellular localization of 1849-ICG via fluorescence microscopy. NIR-PIT-induced cell death was observed by performing cell viability imaging assay. In contrast to the other test groups, tumor growth was significantly inhibited by NIR-PIT with a statistically significant difference in relative tumor volumes for 27 d after the treatment start date [2.83 ± 0.38 (NIR-PIT) vs 5.42 ± 1.61 (Untreated), vs 4.90 ± 0.87 (NIR), vs 4.28 ± 1.87 (1849-ICG), vs 4.35 ± 1.42 (anti-TF 1849), at Day 27, P < 0.05]. Tumors that received NIR-PIT showed evidence of necrotic cell death-associated features upon hematoxylin-eosin staining accompanied by a decrease in Ki-67-positive cells (a cell proliferation marker) by IHC examination. CONCLUSION: The TF-targeted NIR-PIT with the 1849-ICG conjugate can potentially open a new platform for treatment of TF-expressing pancreatic cancer.

Generation and Application of Monoclonal Antibody Against Lycopene.

A monoclonal antibody (Mab) against lycopene was developed from hybridoma clones obtained from BALB/c mice immunized with trans-isomer of lycopene (t-lycopene, t-LC) conjugated with colloidal gold particles. An alternating immunization schedule which included injection of both formulations of immunogen (without and with Freund's adjuvant) was most effective in the elucidation of a measurable immune response to the t-Lycopene conjugate. Selected hybridoma clones were able to produce an Mab positive in competition assay. In particular, preincubation of 6B9 Mabs with t-LC abolished the ability of 6B9 Mabs to bind LC in the competition assay. Mabs produced by other clones (4F10, 4A3, and 3B12) worked similarly. Analysis of antigen specificity showed that 6B9 Mab raised against t-LC did not recognize other carotenoids such as lutein and carotene. Mab 6B9 was shown to recognize lycopene on a glass surface and in the settings of indirect immunofluorescence experiments performed in cultured hepatocytes and alveolar macrophages incubated with and without lycopene, as well as in sebum and corneocyte specimens from the skin of volunteers supplemented with nutraceutical formulation of lycopene. Newly generated Mabs against lycopene may provide a valuable tool for different analytical assays of lycopene content in various biological, agricultural, and food products.

Pneumotoxicity associated with immune checkpoint inhibitor therapies.

PURPOSE OF REVIEW: Immune checkpoint inhibitor therapies represent a new paradigm in cancer therapeutics, in which the targets are not the cancer cells, but the body's own immune system. Harnessing the immune system to better fight cancer has generated a unique spectrum of immune-related adverse events (IrAEs) that effect virtually every major organ system. Although lung involvement is less common than other forms of IrAEs, its consequences are potentially lethal. This review focuses on the evolving spectrum of lung toxicities associated with the two major classes of immune checkpoint inhibitor therapies, cytotoxic T-cell ligand-4, and programed cell death-1 (PDL-1). RECENT FINDINGS: Lung injury was not reported in the earliest clinical trials of immune checkpoint inhibitors. More recent studies, however, have described unique radiographic and clinical toxicity profiles that differ significantly from lung injury patterns associated with conventional cytotoxic therapies. The pathophysiologic mechanisms of immune-related lung injury, its radiographic and clinical disease spectrum, associated risk factors, and optimal treatment strategies remain poorly understood. SUMMARY: Adverse immune-mediated lung events are increasingly recognized as unique and potentially life-threatening sequelae of checkpoint inhibitor therapies. Early recognition of symptoms and radiographic abnormalities is essential to proper management and successful outcome.

Preclinical Antitumor Efficacy of BAY 1129980-a Novel Auristatin-Based Anti-C4.4A (LYPD3) Antibody-Drug Conjugate for the Treatment of Non-Small Cell Lung Cancer.

C4.4A (LYPD3) has been identified as a cancer- and metastasis-associated internalizing cell surface protein that is expressed in non-small cell lung cancer (NSCLC), with particularly high prevalence in the squamous cell carcinoma (SCC) subtype. With the exception of skin keratinocytes and esophageal endothelial cells, C4.4A expression is scarce in normal tissues, presenting an opportunity to selectively treat cancers with a C4.4A-directed antibody-drug conjugate (ADC). We have generated BAY 1129980 (C4.4A-ADC), an ADC consisting of a fully human C4.4A-targeting mAb conjugated to a novel, highly potent derivative of the microtubule-disrupting cytotoxic drug auristatin via a noncleavable alkyl hydrazide linker. In vitro, C4.4A-ADC demonstrated potent antiproliferative efficacy in cell lines endogenously expressing C4.4A and inhibited proliferation of C4.4A-transfected A549 lung cancer cells showing selectivity compared with a nontargeted control ADC. In vivo, C4.4A-ADC was efficacious in human NSCLC cell line (NCI-H292 and NCI-H322) and patient-derived xenograft (PDX) models (Lu7064, Lu7126, Lu7433, and Lu7466). C4.4A expression level correlated with in vivo efficacy, the most responsive being the models with C4.4A expression in over 50% of the cells. In the NCI-H292 NSCLC model, C4.4A-ADC demonstrated equal or superior efficacy compared to cisplatin, paclitaxel, and vinorelbine. Furthermore, an additive antitumor efficacy in combination with cisplatin was observed. Finally, a repeated dosing with C4.4A-ADC was well tolerated without changing the sensitivity to the treatment. Taken together, C4.4A-ADC is a promising therapeutic candidate for the treatment of NSCLC and other cancers expressing C4.4A. A phase I study (NCT02134197) with the C4.4A-ADC BAY 1129980 is currently ongoing. Mol Cancer Ther; 16(5); 893-904. ©2017 AACR.

New insights into the pretargeting approach to image and treat tumours.

Tumour pretargeting is a promising strategy for cancer diagnosis and therapy allowing for the rational use of long circulating, highly specific monoclonal antibodies (mAbs) for both non-invasive cancer radioimmunodetection (RID) and radioimmunotherapy (RIT). In contrast to conventional RID/RIT where the radionuclides and oncotropic vector molecules are delivered as presynthesised radioimmunoconjugates, the pretargeting approach is a multistep procedure that temporarily separates targeting of certain tumour-associated antigens from delivery of diagnostic or therapeutic radionuclides. In principle, unlabelled, highly tumour antigen specific mAb conjugates are, in a first step, administered into a patient. After injection, sufficient time is allowed for blood circulation, accumulation at the tumour site and subsequent elimination of excess mAb conjugates from the body. The small fast-clearing radiolabelled effector molecules with a complementary functionality directed to the prelocalised mAb conjugates are then administered in a second step. Due to its fast pharmacokinetics, the small effector molecules reach the malignant tissue quickly and bind the local mAb conjugates. Thereby, corresponding radioimmunoconjugates are formed in vivo and, consequently, radiation doses are deposited mainly locally. This procedure results in a much higher tumour/non-tumour (T/NT) ratio and is favourable for cancer diagnosis and therapy as it substantially minimises the radiation damage to non-tumour cells of healthy tissues. The pretargeting approach utilises specific non-covalent interactions (e.g. strept(avidin)/biotin) or covalent bond formations (e.g. inverse electron demand Diels-Alder reaction) between the tumour bound antibody and radiolabelled small molecules. This tutorial review descriptively presents this complex strategy, addresses the historical as well as recent preclinical and clinical advances and discusses the advantages and disadvantages of different available variations.

Application of a Plug-and-Play Immunogenicity Assay in Cynomolgus Monkey Serum for ADCs at Early Stages of Drug Development.

Immunogenicity assessment during early stages of nonclinical biotherapeutic development is not always warranted. It is rarely predictive for clinical studies and evidence for the presence of anti-drug antibodies (ADAs) may be inferred from the pharmacokinetic (PK) profile. However, collecting and banking samples during the course of the study are prudent for confirmation and a deeper understanding of the impact on PK and safety. Biotherapeutic-specific ADA assays commonly developed can require considerable time and resources. In addition, the ADA assay may not be ready when needed if the study of PK and safety data triggers assay development. During early stages of drug development for antibody-drug conjugates (ADCs), there is the added complication of the potential inclusion of several molecular variants in a study, differing in the linker and/or drug components. To simplify analysis of ADAs at this stage, we developed plug-and-play generic approaches for both the assay format and the data analysis steps. Firstly, the assay format uses generic reagents to detect ADAs. Secondly, we propose a cut point methodology based on animal specific baseline variability instead of a population data approach. This assay showed good sensitivity, drug tolerance, and reproducibility across a variety of antibody-derived biotherapeutics without the need for optimization across molecules.

Prospects and progress of antibody-drug conjugates in solid tumor therapies.

INTRODUCTION: Antibody-drug conjugates (ADCs) for targeted chemotherapy have evolved in the past 2-3 decades to become a validated clinical cancer therapy modality. While considerable strides have been made in treating hematological tumors, challenges remain in the more difficult-to-treat solid cancers. AREAS COVERED: The current model for a successful ADC uses a highly potent cytotoxic drug as the payload, with stringent linker requirements and limited substitutions. In solid tumor treatment, a number of ADCs have not progressed beyond Phase I clinical trials, indicating a need to optimize additional factors governing translational success. In this regard, insights from mathematical modeling provide a number of pointers relevant to target antigen and antibody selection. Together with the choice of targets, these can be expected to complement the gains made in ADC design towards the generation of better therapeutics. EXPERT OPINION: While highly potent microtubule inhibitors continue to dominate the current ADC landscape, there are promising data with other drugs, linkers, and targets that suggest a more flexible model for a successful ADC is evolving. Such changes will undoubtedly lead to the consideration of new targets and constructs to overcome some of the unique natural barriers that impede the delivery of cytotoxic agents in solid tumor.

Biological therapies in rheumatic diseases.

The development of the biological drugs has revolutionized the therapeutic approach of the chronic inflammatory rheumatic diseases, particularly in patients resistant to standard treatment. These drugs are characterized by an innovative mechanism of action, based on the targeted inhibition of specific molecular or cellular targets directly involved in the pathogenesis of the diseases: pro-inflammatory cytokines (tumor necrosis factor, interleukin-1 and 6), CTLA-4, and molecules involved in the activation, differentiation and maturation of B cells. Their use has indeed allowed for a better prognosis in several rheumatic diseases (such as rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, systemic lupus erythematosus) and to obtain a clinical remission. In the present review we give an overview of the biological drugs currently available for the treatment of the rheumatic diseases, analyzing the different mechanism of action, the therapeutic indications and efficacy data, and adverse events.

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.

Effects of charge on antibody tissue distribution and pharmacokinetics.

Antibody pharmacokinetics and pharmacodynamics are often governed by biological processes such as binding to antigens and other cognate receptors. Emphasis must also be placed, however, on fundamental physicochemical properties that define antibodies as complex macromolecules, including shape, size, hydrophobicity, and charge. Electrostatic interactions between anionic cell membranes and the predominantly positive surface charge of most antibodies can influence blood concentration and tissue disposition kinetics in a manner that is independent of antigen recognition. In this context, the deliberate modification of antibodies by chemical means has been exploited as a valuable preclinical research tool to investigate the relationship between net molecular charge and biological disposition. Findings from these exploratory investigations may be summarized as follows: (I) shifts in isoelectric point of approximately one pI unit or more can produce measurable changes in tissue distribution and kinetics, (II) increases in net positive charge generally result in increased tissue retention and increased blood clearance, and (III) decreases in net positive charge generally result in decreased tissue retention and increased whole body clearance. Understanding electrostatic interactions between antibodies and biological matrices holds relevance in biotechnology, especially with regard to the development of immunoconjugates. The guiding principles and knowledge gained from preclinical evaluation of chemically modified antibodies will be discussed and placed in the context of therapeutic antibodies that are currently marketed or under development, with a particular emphasis on pharmacokinetic and disposition properties.

A critical evaluation of a nicotine vaccine within a self-administration behavioral model.

(S)-Nicotine is a psychostimulant legal drug responsible for causing addiction to tobacco smoking. Tobacco smoking has been irrevocably linked to a number of serious diseases and at present is considered the leading cause of preventable death in the United States. Despite well-documented adverse medical consequences, nicotine addiction has historically been one of the hardest to break. Current therapies have offered limited success and show high rates of relapse, emphasizing the need to engineer alternative therapies to aid nicotine cessation. The current study presents a protein-based immunopharmacotherapy approach for the treatment of nicotine addiction. Immunopharmacotherapy aims to use highly specific antibodies to blunt passage of drug into the brain thus minimizing reinforcing effects on the reward pathways of the central nervous system. Generation of a successful vaccine heavily relies on appropriate optimization of hapten design, immunogenic carrier and adjuvant. Modification of a classical nicotine hapten in conjugation with three distinct carrier proteins allowed for priming of a nicotine vaccine able to elicit significant amounts of nicotine-specific antibodies. Increased self-administration with use of a high drug dose (0.03 mg/kg/infusion; approximately 2 cigarettes in human) was observed in the vaccinated versus control animals suggesting a compensatory pattern and possibly reduced passage of nicotine to the brain. These results support the hypothesis that proper optimization of vaccine formulations could lead to successful nicotine vaccines for human use.