Anti-drug Antibody Responses Research Articles

A generic anti-drug antibody assay for monoclonal antibody therapeutics with broad dynamic range eliminates the need for titer evaluation in preclinical studies

In preclinical protein therapeutic development studies, the emergence of anti-drug antibodies (ADA) can potentially impact drug pharmacokinetics and safety. While immunogenicity assessment is not mandatory in preclinical studies, banking samples can be valuable for interpreting unexpected pharmacological responses. Immunoassays that use generic reagents across different drug molecules can simplify ADA assessment and expedite sample evaluations. This work showcases the ability of the Gyrolab automated immunoassay platform to detect and quantify both drug-free and drug-bound (total) ADAs to monoclonal antibody (mAb) therapeutics in cynomolgus monkey preclinical studies. Compared to the previously reported total ADA ELISA, the Gyrolab assay exhibited a wider signal dynamic range and increased drug tolerance. Similar sensitivity, dynamic range and cut point factors were observed for four therapeutic mAbs of different isotypes using the Gyrolab assay. Here we present a comparison of ADA assays using bridging ELISA, total ADA ELISA and total ADA Gyrolab formats in a cynomolgus monkey study where the subjects were treated with a single dose of a mAb therapeutic. We demonstrate that the total ADA assays detected host ADA responses at earlier time points compared to the bridging ELISA. The Gyrolab assay has the best correlation between signal-to-noise (S/N) and titer over a wide ADA concentration range, highlighting the utility of Gyrolab in S/N reporting of ADA response to eliminate the need for secondary titer assays. Collectively, our results demonstrate that the generic ADA Gyrolab assay minimizes the necessity for extensive assay development and optimization for therapeutic mAbs, streamlining preclinical immunogenicity assessment to enable interpretation of pharmacological data.

Immunogenicity of Atezolizumab: Influence of Testing Method and Sampling Frequency on Reported Anti-drug Antibody Incidence Rates.

Measurement of anti-drug antibodies (ADA) to assess the incidence of ADA in a clinical trial is a critical step in immunogenicity assessment during the development of a protein therapeutic. We developed novel graphical approaches to illustrate clinical trial ADA data for the PD-L1 inhibitor atezolizumab (Tecentriq) that included a systematic analysis of the impact of the timing of ADA sampling and ADA assay drug tolerance on reported ADA incidence. We found that approaches used across the industry for ADA incidence analysis provide a limited view of immunogenicity in oncology studies, where ADA detection may be confounded by both drug dosage and patient attrition. Moreover, these approaches can miss important temporal information about the immune response. Our results demonstrated that the methodology of ADA assessment for the atezolizumab program was specifically designed to capture most ADA responses to ensure accurate reporting of ADA incidence. We further showed that the use of sparse sampling and/or ADA test methods with insufficient drug tolerance may result in a significant underreporting of ADA incidence. We conclude that the comparison of ADA incidence between different drugs can be highly misleading and that a test method with appropriate sensitivity in the presence of the drug and a clinical sampling scheme that is aligned with ADA responses to a drug is required to accurately report ADA incidence.

Ro60-Roles in RNA Processing, Inflammation, and Rheumatic Autoimmune Diseases.

The Ro60/SSA2 autoantigen is an RNA-binding protein and a core component of nucleocytoplasmic ribonucleoprotein (RNP) complexes. Ro60 is essential in RNA metabolism, cell stress response pathways, and cellular homeostasis. It stabilises and mediates the quality control and cellular distribution of small RNAs, including YRNAs (for the 'y' in 'cytoplasmic'), retroelement transcripts, and misfolded RNAs. Ro60 transcriptional dysregulation or loss of function can result in the generation and release of RNA fragments from YRNAs and other small RNAs. Small RNA fragments can instigate an inflammatory cascade through endosomal toll-like receptors (TLRs) and cytoplasmic RNA sensors, which typically sense pathogen-associated molecular patterns, and mount the first line of defence against invading pathogens. However, the recognition of host-originating RNA moieties from Ro60 RNP complexes can activate inflammatory response pathways and compromise self-tolerance. Autoreactive B cells may produce antibodies targeting extracellular Ro60 RNP complexes. Ro60 autoantibodies serve as diagnostic markers for various autoimmune diseases, including Sjögren's disease (SjD) and systemic lupus erythematosus (SLE), and they may also act as predictive markers for anti-drug antibody responses among rheumatic patients. Understanding Ro60's structure, function, and role in self-tolerance can enhance our understanding of the underlying molecular mechanisms of autoimmune conditions.

Neutralizing Antibody Sample Testing and Report Harmonization

Immunogenicity testing and characterization is an important part of understanding the immune response to administration of a protein therapeutic. Neutralizing antibody (NAb) assays are used to characterize a positive anti-drug antibody (ADA) response. Harmonization of reporting of NAb assay performance and results enables efficient communication and expedient review by industry and health authorities. Herein, a cross-industry group of NAb assay experts have harmonized NAb assay reporting recommendations and provided a bioanalytical report (BAR) submission editable template developed to facilitate agency filings. This document addresses key bioanalytical reporting gaps and provides a report structure for documenting clinical NAb assay performance and results. This publication focuses on the content and presentation of the NAb sample analysis report including essential elements such as the method, critical reagents and equipment, data analysis, study samples, and results. The interpretation of immunogenicity data, including the evaluation of the impact of NAb on safety, exposure, and efficacy, is out of scope of this publication.Graphical

Adeno-associated viral delivery of Env-specific antibodies prevents SIV rebound after discontinuing antiretroviral therapy.

An alternative to lifelong antiretroviral therapy (ART) is needed to achieve durable control of HIV-1. Here we show that adeno-associated virus (AAV)-delivery of two rhesus macaque antibodies to the SIV envelope glycoprotein (Env) with potent neutralization and antibody-dependent cellular cytotoxicity can prevent viral rebound in macaques infected with barcoded SIV mac 239M after discontinuing suppressive ART. Following AAV administration, sustained antibody expression with minimal anti-drug antibody responses was achieved in all but one animal. After ART withdrawal, SIV replication rebounded within two weeks in all of the control animals but remained below the threshold of detection in plasma (<15 copies/mL) for more than a year in four of the eight animals that received AAV vectors encoding Env-specific antibodies. Viral sequences from animals with delayed rebound exhibited restricted barcode diversity and antibody escape. Thus, sustained expression of antibodies with potent antiviral activity can afford durable, ART-free containment of pathogenic SIV infection.

AERIFY-1/2: two phase 3, randomised, controlled trials of itepekimab in former smokers with moderate-to-severe COPD

BackgroundAccumulating data implicate interleukin (IL)-33, a proinflammatory cytokine released locally upon epithelial cell damage, in the pathogenesis of COPD. In a phase 2 study, itepekimab, a human monoclonal antibody against IL-33, reduced exacerbations and improved lung function in a subgroup analysis of former smokers with COPD with an acceptable safety profile.MethodsThe study designs of AERIFY-1 and AERIFY-2 are described in this article.DiscussionThe primary objective of AERIFY-1/2 (NCT04701983/NCT04751487), two phase 3 randomised, double-blind, placebo-controlled trials, is to assess the efficacy and safety of itepekimabversusplacebo in a population of former smokers with moderate-to-severe COPD over up to 52 weeks. An additional secondary population of current smokers are being enrolled in AERIFY-2. These two studies will enrol patients (aged 40–85 years) with COPD and chronic bronchitis who had ≥2 moderate or ≥ 1 severe exacerbations within the previous year despite standard-of-care triple or double background therapy. All participants are required to have ≥10-pack-year smoking history, and ≥6 months since smoking cessation for former smokers. The primary end-point is the annualised rate of moderate or severe acute exacerbation of COPD. Secondary end-points include change from baseline in pre- and post-bronchodilator forced expiratory volume in 1 s, and annualised frequency of severe exacerbations. Symptomatic end-points include Evaluating Respiratory Symptoms in COPD and St. George's Respiratory Questionnaire, safety and anti-drug antibody responses.

Selection of positive controls and their impact on anti-drug antibody assay performance

Development of assays to reliably identify and characterize anti-drug antibodies (ADAs) depends on positive control anti-idiotype (anti-id) reagents, which are used to demonstrate that the standards recommended by regulatory authorities are met. This work employs a set of therapeutic antibodies under clinical development and their corresponding anti-ids to investigate how different positive control reagent properties impact ADA assay development. Positive controls exhibited different response profiles and apparent assay analytical sensitivity values depending on assay format. Neither anti-id affinity for drug, nor sensitivity in direct immunoassays related to sensitivity in ADA assays. Anti-ids were differentially able to detect damage to drug conjugates used in bridging assays and were differentially drug tolerant. These parameters also failed to relate to assay sensitivity, further complicating selection of anti-ids for use in ADA assay development based on functional characteristics. Given this variability among anti-ids, alternative controls that could be employed across multiple antibody drugs were investigated as a more uniform means to define ADA detection sensitivity across drug products and assay protocols, which could help better relate assay results to clinical risks of ADA responses. Overall, this study highlights the importance of positive control selection to reliable detection and clinical interpretation of the presence and magnitude of ADA responses.

Implications of Immunogenicity Testing for Therapeutic Monoclonal Antibodies: A Quantitative Pharmacology Framework

The interpretation of immunogenicity results for a mAb product and prediction of its clinical consequences remain difficult, despite enormous advances in methodologies and efforts toward the best practice for consistent data generation and reporting. To this end, the contribution from the clinical pharmacology discipline has been largely limited to comparing descriptively the pharmacokinetic (PK) profiles by antidrug antibodies (ADA) status or testing the significance of ADA as a covariate in a population PK setting, similar to the practice for small-molecule drugs in investigating the effect of an intrinsic/extrinsic factor on the drug disposition. There is a need for a mAb disposition framework that captures the dynamics of ADA formation and drug’s interactions with the ADA and target as parts of the drug distribution and elimination. Here we describe such a framework and examine it against the PK, ADA, and clinical response data from a phase 3 trial in patients treated with adalimumab. The proposed framework offered a generalized understanding of how the dose, target affinity, and drug/ADA analyte forms affects the manifestation of ADA response with regard to its detections and alterations of drug disposition and effectiveness. Furthermore, as an example, its utility for dose considerations was demonstrated through predicting for late-stage trials of a PCSK9 inhibitor in terms of development in ADA incidence and titers, and consequences on the drug disposition, interaction with target, and downstream lowering effect on LDL-C.Graphical

Phase 1b/2 study of penpulimab (AK105), an antiprogrammed cell death-1 immunoglobulin G1 antibody, in advanced or metastatic solid tumors (AK105-204).

Penpulimab, a new-generation antiprogrammed cell death-1 immunoglobulin G1 monoclonal antibody, was engineered to optimize receptor occupancy and eliminate fragment crystallizable γ-mediated effector function. In this multicenter, phase 1b/2, multicohort study, the objective was to investigate the efficacy, safety, and immunogenicity of penpulimab in advanced solid tumors. Patients who had unresectable, advanced solid tumors were enrolled from six centers and received 200mg penpulimab on day 1 every 2weeks for up to 24months. The primary end point was the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors, version criteria 1.1. Between September 2, 2019, and January 1, 2020, 65 patients were enrolled and received penpulimab. At the time of data cutoff (May 11, 2022), the median follow-up was 12.6months (range, 1.1-28.6 months). The ORR was 12.3 (95% confidence interval [CI], 5.5%-22.8%), with three (4.6%) complete responses and five (7.7%) partial responses. Twelve patients (18.5%) achieved stable disease, resulting in a disease control rate of 30.8% (95% CI, 19.9%-43.4%). The median duration of response was not reached (95% CI, 6.70 months to not estimable). In all cohorts, the median progression-free survival was 1.74months (95% CI, 1.41-2.69 months), and the median overall survival was 16.59months (95% CI, 7.82-22.18 months). Grade 3 or greater treatment-related adverse events and immune-related adverse events occurred in 9.2% and 27.7% of patients, respectively. Positive antidrug antibody responses to penpulimab were observed in one patient (1.8%). Penpulimab showed promising antitumor activity with an acceptable safety profile, offering a potential new treatment approach for solid tumors. These findings supported the evaluation of penpulimab's durable activity and safety, as monotherapy or in combination therapy, in specific malignancies.

Systemic exposure to aflibercept after intravitreal injection in premature neonates with retinopathy of prematurity: results from the FIREFLEYE randomized phase 3 study

BackgroundThere are no data on pharmacokinetics, pharmacodynamics, and immunogenicity of intravitreal aflibercept in preterm infants with retinopathy of prematurity (ROP). FIREFLEYE compared aflibercept 0.4 mg/eye and laser photocoagulation in infants with acute-phase ROP requiring treatment.MethodsInfants (gestational age ≤32 weeks or birthweight ≤1500 g) with treatment-requiring ROP in ≥1 eye were randomized 2:1 to receive aflibercept 0.4 mg or laser photocoagulation at baseline in this 24-week, randomized, open-label, noninferiority, phase 3 study. Endpoints include concentrations of free and adjusted bound aflibercept in plasma, pharmacokinetic/pharmacodynamic exploration of systemic anti-vascular endothelial growth factor effects, and immunogenicity.ResultsOf 113 treated infants, 75 received aflibercept 0.4 mg per eye at baseline (mean chronological age: 10.4 weeks), mostly bilaterally (71 infants), and with 1 injection/eye (120/146 eyes). Concentrations of free aflibercept were highly variable, with maximum concentration at day 1, declining thereafter. Plasma concentrations of adjusted bound (pharmacologically inactive) aflibercept increased from day 1 to week 4, decreasing up to week 24. Six infants experienced treatment-emergent serious adverse events within 30 days of treatment; aflibercept concentrations were within the range observed in other infants. There was no pattern between free and adjusted bound aflibercept concentrations and blood pressure changes up to week 4. A low-titer (1:30), non-neutralizing, treatment-emergent anti-drug antibody response was reported in 1 infant, though was not clinically relevant.Conclusions24-week data suggest intravitreal aflibercept for treatment of acute-phase ROP is not associated with clinically relevant effects on blood pressure, further systemic adverse events, or immunogenicity.ClinicalTrials.gov IdentifierNCT04004208.

Characterization of anti-drug antibody responses to the T-cell engaging bispecific antibody cibisatamab to understand the impact on exposure.

An appropriately designed pharmacokinetic (PK) assay that is sensitive for anti-drug antibody (ADA) impact on relevant exposure is an alternative strategy to understand the neutralizing potential of ADAs. However, guidance on how to develop such PK assays and how to confirm the functional ADA impact on exposure is missing. Here, the PK assay of a T-cell-engaging bispecific antibody, cibisatamab, was developed based on its mechanism of action (MoA). Using critical monoclonal anti-idiotypic (anti-ID) antibody positive controls as ADA surrogates, the impact on exposure was evaluated pre-clinically. In a phase I clinical trial (NCT02324257), initial data suggest that the combination of ADA and PK assays for correlation of the ADA response with cibisatamab exposure. To understand the neutralizing potential of patient-derived ADAs on drug activity, advanced ADA characterization has been performed. Structural binding analysis of ADAs to antibody domains of the drug and its impact on targeting were assessed. For this purpose, relevant patient ADA binding features were identified and compared with the specific monoclonal anti-ID antibody-positive controls. Comparable results of target binding inhibition and similar impacts on exposure suggest that the observed reduction of Cmax and Ctrough levels in patients is caused by the neutralizing potential of ADAs and allows a correlation between ADA response and loss of exposure. Therefore, the described study provides important functional aspects for the development of an appropriately designed PK assay for bispecific antibodies as an alternative option towards understanding the neutralizing ADA impact on exposure.

Synthetically mannosylated antigens induce antigen-specific humoral tolerance and reduce anti-drug antibody responses to immunogenic biologics

Immunogenic biologics trigger an anti-drug antibody (ADA) response in patients that reduces efficacy and increases adverse reactions. Our laboratory has shown that targeting protein antigen to the liver microenvironment can reduce antigen-specific Tcell responses; herein, we present a strategy to increase delivery of otherwise immunogenic biologics to the liver via conjugation to a synthetic mannose polymer, p(Man). This delivery leads to reduced antigen-specific T follicular helper cell and B cell responses resulting in diminished ADA production, which is maintained throughout subsequent administrations of the native biologic. We find that p(Man)-antigen treatment impairs the ADA response against recombinant uricase, a highly immunogenic biologic, without a dependence on hapten immunodominance or control by T regulatory cells. We identify increased Tcell receptor signaling and increased apoptosis and exhaustion in Tcells as effects of p(Man)-antigen treatment via transcriptomic analyses. This modular platform may enhance tolerance to biologics, enabling long-term solutions for an ever-increasing healthcare problem.

Therapeutically targeting type I interferon directly to XCR1+ dendritic cells reveals the role of cDC1s in anti-drug antibodies.

Conventional type 1 dendritic cells (cDC1s) are superior in antigen cross-presentation and priming CD8+ T cell anti-tumor immunity and thus, are a target of high interest for cancer immunotherapy. Type I interferon (IFN) is a potent inducer of antigen cross-presentation, but, unfortunately, shows only modest results in the clinic given the short half-life and high toxicity of current type I IFN therapies, which limit IFN exposure in the tumor. CD8+ T cell immunity is dependent on IFN signaling in cDC1s and preclinical studies suggest targeting IFN directly to cDC1s may be sufficient to drive anti-tumor immunity. Here, we engineered an anti-XCR1 antibody (Ab) and IFN mutein (IFNmut) fusion protein (XCR1Ab-IFNmut) to determine whether systemic delivery could drive selective and sustained type I IFN signaling in cDC1s leading to anti-tumor activity and, in parallel, reduced systemic toxicity. We found that the XCR1Ab-IFNmut fusion specifically enhanced cDC1 activation in the tumor and spleen compared to an untargeted control IFN. However, multiple treatments with the XCR1Ab-IFNmut fusion resulted in robust anti-drug antibodies (ADA) and loss of drug exposure. Using other cDC1-targeting Ab-IFNmut fusions, we found that localizing IFN directly to cDC1s activates their ability to promote ADA responses, regardless of the cDC1 targeting antigen. The development of ADA remains a major hurdle in immunotherapy drug development and the cellular and molecular mechanisms governing the development of ADA responses in humans is not well understood. Our results reveal a role of cDC1s in ADA generation and highlight the potential ADA challenges with targeting immunostimulatory agents to this cellular compartment.

Anti-drug Antibody Magnitude and Clinical Relevance Using Signal to Noise (S/N): Bococizumab Case Study.

Historically, the biopharmaceutical industry has used titer to characterize the magnitude of an anti-drug antibody (ADA) response. While reporting levels of antibodies in terms of titer is generally understood and accepted by regulatory and medical communities, titer values are inherently variable given the multiple serial dilutions and reporting a value either directly before or interpolated at the assay cut point on the lower plateau of the assay curve range. Using S/N is an appealing alternative approach to titer as it simplifies analysis with less dilutions, significantly reducing testing, time, and resources and provides a more precise value potentially differentiating low-level ADA responses. Current bridging electrochemiluminescence (ECL) ADA assays using Meso Scale Discovery (MSD) platform are also significantly more sensitive and drug tolerant with wider assay ranges compared to historic ELISA platforms; therefore, ADA response based on S/N may help differentiate and identify those ADA samples that are more likely to be clinically relevant. Bococizumab is a humanized monoclonal antibody targeting proprotein convertase subtilisin-kexin type 9 (PCSK9), which reduces plasma levels of low-density lipoprotein (LDL) cholesterol. Bococizumab was discontinued during Phase 3 clinical development based in part on the high rate of ADA and wide variation in LDL cholesterol responses among patients. The impact of anti-bococizumab antibodies on pharmacokinetic (PK) and pharmacodynamic (PD) endpoints was originally assessed using titer. Retrospective analysis of anti-bococizumab ADA responses using S/N ratios illustrates that S/N is an acceptable alternative to titer for characterizing the magnitude of ADA response and interpretation of clinically relevant ADA.

Evolution of Antidrug Antibody Assays During the Development of Anti-Tissue Factor Pathway Inhibitor Monoclonal Antibody Marstacimab.

Tissue factor pathway inhibitor (TFPI) is an endogenous inhibitor of the extrinsic coagulation pathway. In patients with hemophilia A or B, inhibition of TFPI is an alternative therapeutic approach that augments the extrinsic coagulation pathway. Marstacimab is an investigational fully human monoclonal antibody that binds and neutralizes TFPI and is being evaluated as a prophylactic treatment to prevent or reduce the frequency of bleeding episodes in patients with severe hemophilia A or B, with or without inhibitors (antibodies against coagulation factors). However, the efficacy, safety, and pharmacokinetics of marstacimab may be affected by the induction of antidrug antibody (ADA) responses. Here, we describe the evolution and validation of three quasi-quantitative electrochemiluminescence-based methods to detect marstacimab ADAs, starting from their use in a first-in-human phase 1 study to their use in phase 2 and 3 clinical studies of patients with severe hemophilia. For all three methods, validation criteria evaluated the performance of the assays in screening and confirmatory cut points, precision, selectivity, drug tolerance, target interference, and stability. Additional criteria for validation were dilution linearity (Methods 1 and 2) and low positive control concentration, prozone effect, plate homogeneity, and robustness (Method 3). The three methods met validation criteria and are a potentially valuable tool in detecting the induction of marstacimab ADAs during treatment in patients with hemophilia.

Recent Advancements in AAV-Vectored Immunoprophylaxis in the Nonhuman Primate Model.

Monoclonal antibodies (mAbs) are important treatment modalities for preventing and treating infectious diseases, especially for those lacking prophylactic vaccines or effective therapies. Recent advances in mAb gene cloning from naturally infected or immunized individuals has led to the development of highly potent human mAbs against a wide range of human and animal pathogens. While effective, the serum half-lives of mAbs are quite variable, with single administrations usually resulting in short-term protection, requiring repeated doses to maintain therapeutic concentrations for extended periods of time. Moreover, due to their limited time in circulation, mAb therapies are rarely given prophylactically; instead, they are generally administered therapeutically after the onset of symptoms, thus preventing mortality, but not morbidity. Adeno-associated virus (AAV) vectors have an established record of high-efficiency in vivo gene transfer in a variety of animal models and humans. When delivered to post-mitotic tissues such as skeletal muscle, brain, and heart, or to organs in which cells turn over slowly, such as the liver and lungs, AAV vector genomes assume the form of episomal concatemers that direct transgene expression, often for the lifetime of the cell. Based on these attributes, many research groups have explored AAV-vectored delivery of highly potent mAb genes as a strategy to enable long-term expression of therapeutic mAbs directly in vivo following intramuscular or intranasal administration. However, clinical trials in humans and studies in nonhuman primates (NHPs) indicate that while AAVs are a powerful and promising platform for vectored immunoprophylaxis (VIP), further optimization is needed to decrease anti-drug antibody (ADA) and anti-capsid antibody responses, ultimately leading to increased serum transgene expression levels and improved therapeutic efficacy. The following review will summarize the current landscape of AAV VIP in NHP models, with an emphasis on vector and transgene design as well as general delivery system optimization. In addition, major obstacles to AAV VIP, along with implications for clinical translation, will be discussed.

Long-term Prophylaxis Against Aerosolized Marburg Virus in Nonhuman Primates With an Afucosylated Monoclonal Antibody.

Marburg virus (MARV) causes a hemorrhagic fever disease in human and nonhuman primates with high levels of morbidity and mortality. Concerns about weaponization of aerosolized MARV have spurred the development of nonhuman primate (NHP) models of aerosol exposure. To address the potential threat of aerosol exposure, a monoclonal antibody that binds MARV glycoprotein was tested, MR186YTE, for its efficacy as a prophylactic. MR186YTE was administered intramuscularly to NHPs at 15 or 5 mg/kg 1 month prior to MARV aerosol challenge. Seventy-five percent (3/4) of the 15 mg/kg dose group and 50% (2/4) of the 5 mg/kg dose group survived. Serum analyses showed that the NHP dosed with 15 mg/kg that succumbed to infection developed an antidrug antibody response and therefore had no detectable MR186YTE at the time of challenge. These results suggest that intramuscular dosing of mAbs may be a clinically useful prophylaxis for MARV aerosol exposure.

Phase 1 clinical trial results for NG-350A, a novel transgene-armed and tumor-selective vector: Differential effects of intravenous (IV) versus intratumoral (IT) dosing on immune pharmacodynamics (PD).

2572 Background: Tumor-selective therapeutic viral vectors are often limited to IT delivery. NG-350A, a blood stable adenoviral vector, selectively replicates in tumors and expresses an agonist anti-CD40 payload. We assessed the impact of IV vs IT delivery during the phase 1 FORTITUDE study (NCT03852511). Methods: NG-350A was dose-escalated in separate IT or IV cohorts of patients (pts) with metastatic/advanced epithelial tumors. Pts received either 1 (Day [D] 1) or 4 IT injections (D1, 8, 15, 22) of up to 1x1012 viral particles (vp) or 3 IV infusions completed in &lt;9 days (doses of 1x1011 to 6x1012 vp). Serum samples were taken immediately after dosing (pharmacokinetics [PK]) and during follow-up (PD). Baseline and on-treatment (D15+) tumor biopsies were taken. Results: In total, 25 pts received NG-350A monotherapy, 9 by IT and 16 by IV dosing. Both IV and IT dosing elicited similar anti-drug (virus) antibody responses and limited viral shedding. Peak vp Cmax was variable with IT dosing but dose-related with IV dosing. Vector DNA was detected by qPCR in tumor biopsies after higher IV dose levels (including up to ~7 weeks post dosing) and IT injection. Dose-dependent, sustained and specific increases in inflammatory cytokines related to the expected effects and timing of the anti-CD40 transgene production (IL-12, IL-17A, IL-2, IFNγ) were detected in serum of pts treated at higher IV doses. By contrast, limited evidence of such PD effects was seen with IT dosing. Transgene was not detectable in core needle biopsies; however, a novel serum biomarker assay detected transgene mRNA at D8 or D15 in five pts who received higher IV dose levels. Importantly, both IV and IT dosed NG–350A was well-tolerated, with no treatment-related SAEs occurring in &gt;1 pt and no DLTs at the highest dose levels tested. No evidence of anti-CD40 transgene-related toxicity was seen with IV or IT dosing, with few hepatic AEs and no Grade ≥3 CRS. Follow-up for imaging was limited; however, stable disease was observed in 3/6 pts at IV Dose Level 3. Conclusions: This analysis provides the first clear evidence that an IV-dosed tumor-selective viral vector can drive expression of immuno-stimulatory payloads with functional PD consequences in advanced cancers. The improved PK and PD profile of IV vs IT dosed NG-350A also highlights the benefits of systemic delivery for such vectors. Dose-escalation of NG-350A + pembrolizumab to identify a dose for efficacy assessments continues in the FORTIFY study (NCT05165433). Clinical trial information: NCT03852511 . [Table: see text]

Synthetically mannosylated antigens impair the antigen-specific humoral immune response and prolong the therapeutic efficacy of immunogenic protein drugs

Abstract Immunogenic protein drugs trigger an anti-drug antibody (ADA) response in patients which reduces drug efficacy and increases adverse reactions. Our lab has previously shown that targeting antigen to the liver microenvironment can reduce antigen-specific T cell responses; herein, we present a novel strategy to further increase delivery of an antigen to the tolerogenic microenvironment of the liver via conjugation to a synthetic mannose polymer (p(Man)). This delivery leads to reduced antigen-specific T follicular helper cell and B cell responses resulting in diminished ADA production which is maintained throughout subsequent administrations of the native biologic. We found that p(Man) treatment impairs the antibody response against recombinant uricase, a highly immunogenic biologic, without a dependence on hapten-skewing or control by Tregs. Through transcriptomic analysis we identified increased TCR signaling and increased apoptosis and exhaustion in T cells as effects of p(Man)-antigen treatment, which may inform the underlying mechanism driving the reduction in ADAs. This modular platform may enhance tolerance to current and future biologics, enabling long-term therapeutic solutions for an ever-increasing healthcare problem.

Serum Albumin fused Flt3L expands a tolDC compartment and amplifies tolerogenic antigen immunotherapy for the prevention of pathogenic anti-drug antibody responses

Abstract From antibodies to enzyme replacement therapies, biologics and protein drugs have become a major part of the medical market and revolutionized medicine. Repeated administration of many of these drugs, however, leads to humoral responses and potentially drug failure via neutralization, clearance, or immune related infusion reactions. Once pathogenic anti-drug antibodies are formed, patients must take broad immunosuppressive drugs, undergo continuous B cell depletion, or discontinue treatment entirely. Currently, no drugs are approved by the FDA to prevent the induction of anti-drug antibodies. Herein, we characterize the effect of our engineered cytokine, Flt3L-SA, in vivoand demonstrate how our molecule expands the dendritic cells while enhancing a tolerogenic, TGFβ expressing subpopulation. We then leverage these dendritic cells to attenuate the antibody response to the highly immunogenic drug Rasburicase and ultimately reduce antibodies by 100-fold when administered as part of a tolerogenic regime with low dose Rasburicase. We also show how this reduction in antibodies results in fewer and less severe infusion reactions upon final challenge, evidencing both a reduction in the antibody response as well as pathology. Future work will aim to determine the exact mechanism by which this tolerance is achieved as well as demonstrate efficacy in the context of a wide range of extremely immunogenic therapies, including enzyme replacement therapeutics for lysosomal storage disorders and AAV therapies. Supported via the Chicago Immunoengineering Innovation Center and the Alper Family Foundation