Anti-drug Antibody Responses Research Articles

A strategy for high antibody expression with low anti-drug antibodies using AAV9 vectors.

Use of adeno-associated virus (AAV) vectors is complicated by host immune responses that can limit transgene expression. Recent clinical trials using AAV vectors to deliver HIV broadly neutralizing antibodies (bNAbs) by intramuscular administration resulted in poor expression with anti-drug antibodies (ADA) responses against the bNAb. Here we compared the expression of, and ADA responses against, an anti-SIV antibody ITS01 when delivered by five different AAV capsids. We first evaluated ITS01 expression from AAV vectors three different 2A peptides. Rhesus macaques were selected for the study based on preexisiting neutralizing antibodies by evaluating serum samples in a neutralization assay against the five capsids used in the study. Macaques were intramuscularly administered AAV vectors at a 2.5x10^12 vg/kg over eight administration sites. ITS01 concentrations and anti-drug antibodies (ADA) were measured by ELISA and a neutralization assay was conducted to confirm ex vivo antibody potency. We observed that ITS01 expressed three-fold more efficiently in mice from AAV vectors in which heavy and light-chain genes were separated by a P2A ribosomal skipping peptide, compared with those bearing F2A or T2A peptides. We then measured the preexisting neutralizing antibody responses against three traditional AAV capsids in 360 rhesus macaques and observed that 8%, 16%, and 42% were seronegative for AAV1, AAV8, and AAV9, respectively. Finally, we compared ITS01 expression in seronegative macaques intramuscularly transduced with AAV1, AAV8, or AAV9, or with the synthetic capsids AAV-NP22 or AAV-KP1. We observed at 30 weeks after administration that AAV9- and AAV1-delivered vectors expressed the highest concentrations of ITS01 (224 µg/mL, n=5, and 216 µg/mL, n=3, respectively). The remaining groups expressed an average of 35-73 µg/mL. Notably, ADA responses against ITS01 were observed in six of the 19 animals. Lastly, we demonstrated that the expressed ITS01 retained its neutralizing activity with nearly the same potency of purified recombinant protein. Overall, these data suggest that the AAV9 capsid is a suitable choice for intramuscular expression of antibodies in nonhuman primates.

Pharmacokinetics of a proposed tocilizumab biosimilar (MSB11456) versus US-licensed tocilizumab: results of a randomized, double-blind, single-intravenous dose study in healthy adults

ABSTRACT Background Tocilizumab, a recombinant monoclonal immunoglobulin G, targets the interleukin-6 receptor. MSB11456 is a proposed tocilizumab biosimilar. Objectives To assess pharmacokinetic equivalence of intravenous MSB11456 to US-licensed tocilizumab. Research design and methods In this double-blind, parallel-group, single-dose study, 128 healthy adults were randomized to a single one-hour 8 mg/kg IV infusion of either MSB11456 or US-licensed tocilizumab. Blood samples were collected pre-dose and at regular intervals up to day 48 post-dose. The primary endpoint pharmacokinetic parameter was analyzed using analysis of variance (ANOVA) model on the natural logarithm of the endpoint (AUC0–last), with treatment as a fixed effect. Immunogenicity and safety data were summarized descriptively. Results Subjects received either MSB11456 (N = 62) or US-licensed tocilizumab (N = 66). Pharmacokinetic bioequivalence, defined as 90% confidence intervals for the geometric least squares mean ratio entirely contained within the 80.00% to 125.00% equivalence limits, was demonstrated between MSB11456 and US-licensed tocilizumab for the primary and secondary pharmacokinetic endpoints. Anti-drug antibody responses, frequency of neutralizing antibodies against tocilizumab, and safety profiles showed no notable between-treatment differences. Safety was comparable between treatments. Conclusions Pharmacokinetic similarity of MSB11456 and US-licensed tocilizumab was demonstrated, with comparable immunogenicity and safety profiles, supporting MSB11455 as a biosimilar to US-licensed tocilizumab. The trial is registered at EudraCT, number 2019–003484-22.

Trials in progress: TAM kinase inhibitor PF-07265807 and sasanlimab plus axitinib in patients with advanced or metastatic renal cell carcinoma—A phase 1, open-label, pharmacokinetic, safety and tolerability study.

TPS743 Background: Tumor-associated macrophage kinases (TAMK) are expressed on tumor cells during malignant transformation. Inhibition of AXL and MERTK, members of the TAMK family, may lower the immune activation threshold and promote antitumor immunity. PF-07265807 (ARRY-067) is a small-molecule inhibitor of MERTK and AXL showing antitumor activity in preclinical models as monotherapy or combined with anti-programmed cell death protein 1 (anti-PD-1) antibodies (ab). Sasanlimab is an anti-PD-1 ab with acceptable safety profile being tested (300 mg SC Q4W, Phase 3) in non-muscle invasive bladder cancer. Axitinib is a VEGF inhibitor approved (single agent and combined with anti-PD-1 inhibitors) for advanced renal cell carcinoma (RCC). This first-in-human Phase 1, open-label, multi-center study (NCT04458259) will evaluate the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of PF-07265807 in patients (pts) with advanced or metastatic solid tumors as a single agent and in combination with sasanlimab with or without axitinib. We describe here the dose escalation (Part 3) and dose expansion (Part 4) for the triplet combination of PF-07265807 + sasanlimab + axitinib. Methods: Eligible participants for the triplet cohorts are adult pts with confirmed unresectable advanced or metastatic clear cell RCC, with estimated creatinine clearance ≥30 mL/min and urinary protein <2+ or ≥2+ but 24-h urine protein:creatinine ratio <2 g/24 h. Pts for Part 4 need to have intermediate and poor risk RCC and no prior systemic therapy for metastatic disease. Other key eligibility criteria: measurable disease by RECIST 1.1 or non-measurable disease, ECOG PS 0–2, adequate bone marrow and liver function, and resolved acute effects of prior therapy. Each cycle is 21 days. Part 3 will determine the maximum tolerated dose/recommended phase 2 dose (MTD/RP2D) of PF-07265807 in triplet therapy using a Bayesian logistic regression model and the escalation with overdose control principle. After the MTD/RP2D is identified, Part 4 will further evaluate the safety and preliminary efficacy of PF-07265807 combined with sasanlimab and axitinib. Treatment with study drug will continue until disease progression, consent withdrawal, or unacceptable toxicity, whichever occurs first. Primary endpoints of Part 3 are incidence of dose-limiting toxicities, adverse events (AE), and laboratory (lab) abnormalities. For Part 4, the primary endpoints are objective response rate and complete response rate; secondary endpoints include disease control rate; time-to-event endpoints; AEs; lab abnormalities; concentrations of PF-07265807 and its metabolite, sasanlimab, and axitinib; and incidence and titer of anti-sasanlimab anti-drug antibodies response. The study started in late 2020 and is recruiting. Clinical trial information: NCT04458259 .

Anti-brolucizumab immune response as one prerequisite for rare retinal vasculitis/retinal vascular occlusion adverse events.

In October 2019, Novartis launched brolucizumab, a single-chain variable fragment molecule targeting vascular endothelial growth factor A, for the treatment of neovascular age-related macular degeneration. In 2020, rare cases of retinal vasculitis and/or retinal vascular occlusion (RV/RO) were reported, often during the first few months after treatment initiation, consistent with a possible immunologic pathobiology. This finding was inconsistent with preclinical studies in cynomolgus monkeys that demonstrated no drug-related intraocular inflammation, or RV/RO, despite the presence of preexisting and treatment-emergent antidrug antibodies (ADAs) in some animals. In this study, the immune response against brolucizumab in humans was assessed using samples from clinical trials and clinical practice. In the brolucizumab-naïve population, anti-brolucizumab ADA responses were detected before any treatment, which was supported by the finding that healthy donors can harbor brolucizumab-specific B cells. This suggested prior exposure of the immune system to proteins with structural similarity. Experiments on samples showed that naïve and brolucizumab-treated ADA-positive patients developed a class-switched, high-affinity immune response, with several linear epitopes being recognized by ADAs. Only patients with RV/RO showed a meaningful T cell response upon recall with brolucizumab. Further studies in cynomolgus monkeys preimmunized against brolucizumab with adjuvant followed by intravitreal brolucizumab challenge demonstrated that high ADA titers were required to generate ocular inflammation and vasculitis/vascular thrombosis, comparable to RV/RO in humans. Immunogenicity therefore seems to be a prerequisite to develop RV/RO. However, because only 2.1% of patients with ADA develop RV/RO, additional factors must play a role in the development of RV/RO.

A phase I/II study on intracerebroventricular tralesinidase alfa in patients with Sanfilippo syndrome type B.

BackgroundSanfilippo type B is a mucopolysaccharidosis (MPS) with a major neuronopathic component characterized by heparan sulfate (HS) accumulation due to mutations in the NAGLU gene encoding alfa-N-acetyl-glucosaminidase. Enzyme replacement therapy for neuronopathic MPS requires efficient enzyme delivery throughout the brain in order to normalize HS levels, prevent brain atrophy, and potentially delay cognitive decline.MethodsIn this phase I/II open-label study, patients with MPS type IIIB (n = 22) were treated with tralesinidase alfa administered i.c.v. The patients were monitored for drug exposure; total HS and HS nonreducing end (HS-NRE) levels in both cerebrospinal fluid (CSF) and plasma; anti-drug antibody response; brain, spleen, and liver volumes as measured by MRI; and cognitive development as measured by age-equivalent (AEq) scores.ResultsIn the Part 1 dose escalation (30, 100, and 300 mg) phase, a 300 mg dose of tralesinidase alfa was necessary to achieve normalization of HS and HS-NRE levels in the CSF and plasma. In Part 2, 300 mg tralesinidase alfa sustained HS and HS-NRE normalization in the CSF and stabilized cortical gray matter volume (CGMV) over 48 weeks of treatment. Resolution of hepatomegaly and a reduction in spleen volume were observed in most patients. Significant correlations were also established between the change in cognitive AEq score and plasma drug exposure, plasma HS-NRE levels, and CGMV.ConclusionAdministration of tralesinidase alfa i.c.v. effectively normalized HS and HS-NRE levels as a prerequisite for clinical efficacy. Peripheral drug exposure data suggest a role for the glymphatic system in altering tralesinidase alfa efficacy.Trial registrationClinicaltrials.gov NCT02754076.FUNDINGBioMarin Pharmaceutical Inc. and Allievex Corporation.

Functional Deimmunization of Botulinum Neurotoxin Protease Domain via Computationally Driven Library Design and Ultrahigh-Throughput Screening.

Botulinum neurotoxin serotype A (BoNT/A) is a widely used cosmetic agent that also has diverse therapeutic applications; however, adverse antidrug immune responses and associated loss of efficacy have been reported in clinical uses. Here, we describe computational design and ultrahigh-throughput screening of a massive BoNT/A light-chain (BoNT/A-LC) library optimized for reduced T cell epitope content and thereby dampened immunogenicity. We developed a functional assay based on bacterial co-expression of BoNT/A-LC library members with a Förster resonance energy transfer (FRET) sensor for BoNT/A-LC enzymatic activity, and we employed high-speed fluorescence-activated cell sorting (FACS) to identify numerous computationally designed variants having wild-type-like enzyme kinetics. Many of these variants exhibited decreased immunogenicity in humanized HLA transgenic mice and manifested in vivo paralytic activity when incorporated into full-length toxin. One variant achieved near-wild-type paralytic potency and a 300% reduction in antidrug antibody response in vivo. Thus, we have achieved a striking level of BoNT/A-LC functional deimmunization by combining computational library design and ultrahigh-throughput screening. This strategy holds promise for deimmunizing other biologics with complex superstructures and mechanisms of action.

Development of an anti-CAR antibody response in SIV-infected rhesus macaques treated with CD4-MBL CAR/CXCR5 T cells.

T cells expressing a simian immunodeficiency (SIV)-specific chimeric antigen receptor (CAR) and the follicular homing molecule, CXCR5, were infused into antiretroviral therapy (ART) suppressed, SIV-infected rhesus macaques to assess their ability to localize to the lymphoid follicle and control the virus upon ART interruption. While the cells showed evidence of functionality, they failed to persist in the animals beyond 28 days. Development of anti-CAR antibodies could be responsible for the lack of persistence. Potential antigenic sites on the anti-SIV CAR used in these studies included domains 1 and 2 of CD4, the carbohydrate recognition domain (CRD) of mannose-binding lectin (MBL), and an extracellular domain of the costimulatory molecule, CD28, along with short linker sequences. Using a flow cytometry based assay and target cells expressing the CAR/CXCR5 construct, we examined the serum of the CD4-MBL CAR/CXCR5-T cell treated animals to determine that the animals had developed an anti-CAR antibody response after infusion. Binding sites for the anti-CAR antibodies were identified by using alternative CARs transduced into target cells and by preincubation of the target cells with a CD4 blocking antibody. All of the treated animals developed antibodies in their serum that bound to CD4-MBL CAR/CXCR5 T cells and the majority were capable of inducing an ADCC response. The CD4 antibody-blocking assay suggests that the dominant immunogenic components of this CAR are the CD4 domains with a possible additional site of the CD28 domain with its linker. This study shows that an anti-drug antibody (ADA) response can occur even when using self-proteins, likely due to novel epitopes created by abridged self-proteins and/or the self-domain of the CAR connection to a small non-self linker. While in our study, there was no statistically significant correlation between the ADA response and the persistence of the CD4-MBL CAR/CXCR5-T cells in rhesus macaques, these findings suggest that the development of an ADA response could impact the long-term persistence of self-based CAR immunotherapies.

Assessment and impact of dose escalation on anti-drug antibodies in Fabry disease.

Enzyme replacement therapy (ERT) with recombinant α-galactosidase A (AGAL) can lead to the formation of neutralizing anti-drug antibodies (ADA), which significantly limit treatment efficacy in patients with Fabry disease (FD). The effects of dose escalation on ADA titer and plasma globotriaosylsphingosine (lyso-Gb3) level are unknown. We screened 250 FD patients (200 males, 50 females) under ERT for ADAs and assessed the impact of an approved dose escalation in affected patients, focusing on ADA titers and plasma lyso-Gb3. ADA-positive patients were identified by serum-mediated inhibition assays, followed by titration assays to determine the individual inhibitory capacities of ADAs against agalsidase-alfa and agalsidase-beta. 70 (35%) of the male patients were ADA-positive, with a mean inhibitory capacity of 83.5 ± 113.7mg AGAL. Although patients receiving agalsidase-beta showed higher inhibitory capacities (84.7 ± 34.7mg) than patients under agalsidase-alfa (60.3 ± 126.7mg, p<0.001), the "theoretical deficit" to the infused dose was lower in patients receiving agalsidase-beta. In seven patients receiving agalsidase-alfa (0.2 mg/kg) ADAs were saturable by switching patients to agalsidase-beta (1.0 mg/kg). The switch resulted in increasing ADA titers within the first months. In 2 out of 7 (28.6%) therapy switchers, dose escalation could lead to durable ADA saturation. Independent of an increase in ADA titers, lyso-Gb3 levels decrease and cardiac and renal parameters remained stable after dose escalation. Dose escalation results in a heterogeneous, unpredictable ADA response, with more than a quarter of all treatment switchers succeeding in ADA saturation. Longitudinal ADA measurements are required to assess the individual risk of affected patients.

Validation of a Dendritic Cell and CD4+ T Cell Restimulation Assay Contributing to the Immunogenicity Risk Evaluation of Biotherapeutics.

Immunogenicity, defined as the ability to provoke an immune response, can be either wanted (i.e., vaccines) or unwanted. The latter refers to an immune response to protein or peptide therapeutics, characterized by the production of anti-drug antibodies, which may affect the efficacy and/or the safety profiles of these drugs. Consequently, evaluation of the risk of immunogenicity early in the development of biotherapeutics is of critical importance for defining their efficacy and safety profiles. Here, we describe and validate a fit-for-purpose FluoroSpot-based in vitro assay for the evaluation of drug-specific T cell responses. A panel of 24 biotherapeutics with a wide range of clinical anti-drug antibody response rates were tested in this assay. We demonstrated that using suitable cutoffs and donor cohort sizes, this assay could identify most of the compounds with high clinical immunogenicity rates (71% and 78% for sensitivity and specificity, respectively) while we characterized the main sources of assay variability. Overall, these data indicate that the dendritic cell and CD4+ T cell restimulation assay published herein could be a valuable tool to assess the risk of drug-specific T cell responses and contribute to the selection of clinical candidates in early development.

Assessment of the Pharmacokinetics and Safety of Spesolimab, a Humanised Anti-interleukin-36 Receptor Monoclonal Antibody, in Healthy Non-Japanese and Japanese Subjects: Results from Phase I Clinical Studies.

The interleukin-36 signalling pathway is associated with pathogenesis of a number of inflammatory diseases. Spesolimab is a selective, humanised, IgG1 antibody that targets the interleukin-36 receptor. We aimed to evaluate the pharmacokinetics, safety and tolerability of single and multiple doses of spesolimab in healthy non-Japanese and Japanese subjects. Five phase I clinical studies (three placebo-controlled dose-escalation, two open-label) were conducted in healthy volunteers; single or multiple doses of spesolimab were administered by intravenous infusion or subcutaneous injection. Plasma samples were collected to investigate the pharmacokinetics of spesolimab and evaluate changes with respect to dose, frequency of dosing, formulation and injection site. Immunogenicity, safety and tolerability were also assessed. Intravenous spesolimab exhibited target-mediated drug disposition at low doses (0.01-0.3 mg/kg) and linear kinetics at doses ≥0.3mg/kg. Steady state was not attained after the fourth weekly dose because of the long half-life (3-5 weeks). Bioavailability of subcutaneous spesolimab increased with increasing dose over the range of 150-600mg and was higher when administered to the thigh than to the abdomen. The pharmacokinetic profile was consistent between Japanese and non-Japanese subjects. Positive anti-drug antibody responses occurred during the terminal phase of the spesolimab concentration-time profile in 26.7-33.3% and 16.7-37.5% of subjects receiving intravenous and subcutaneous spesolimab, respectively. The impact of anti-drug antibodies on spesolimab pharmacokinetics was low in healthy volunteers, with the impact on spesolimab plasma concentrations only observed in a few subjects at higher titres (≥11,400). No serious adverse events were reported; intravenous doses up to 1200 mg were well tolerated in healthy volunteers. The pharmacokinetic profile and safety data obtained from these phase I clinical studies have been used to guide spesolimab dosing in clinical studies of patients with interleukin-36-mediated diseases. For Studies 1-5, NCT02525679, NCT02852824, NCT03100903, NCT03123094, NCT03617835.

Preclinical Observations of Systemic and Ocular Antidrug Antibody Response to Intravitreally Administered Drugs

Intravitreally administered biotherapeutics can elicit local and systemic immune responses with potentially serious clinical consequences. However, little is known about the mechanisms of ocular antidrug immune response, the incidence of ocular antidrug antibodies (ADAs), and the relationship between ocular and systemic ADA levels. Bioanalytical limitations and poor availability of ocular matrices make studies of ocular immunogenicity particularly challenging. We have recently reported a novel bioanalytical ADA assay and shown its applicability for the ADA detection in ocular matrices. In the present study, we used this assay to analyze a large set of preclinical samples from minipig and cynomolgus monkeys treated with different ocular biotherapeutics. We found a significant association between the incidence of ADAs in plasma and ocular fluids after a single intravitreal administration of the drugs. Importantly, none of the animals with ADA-negative results in plasma had detectable ADAs in ocular fluids and systemic ADA response always preceded the appearance of ocular ADAs. Overall, our results suggest the systemic origin of ocular ADAs and support the use of plasma as a surrogate matrix for the detection of ocular ADA response.Graphical

Trial in Progress: An Open-Label, Multi-Center Phase 2 Study Evaluating Efficacy and Safety of the Masp-2 Inhibitor Narsoplimab in Pediatric Patients with High-Risk Hematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy (HSCT-TMA)

Background: Hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA; also known as TA-TMA) is a potentially life-threatening complication associated with multi-organ injury and significant morbidity and mortality. HSCT-TMA incidence rates of up to 39% have been reported in both pediatric and adult allogeneic HSCT (alloHSCT) recipients; high-risk pediatric patients with proteinuria and evidence of terminal complement activation (elevated sC5b-9) had a 1-year post-HSCT survival of <20% versus 100% in those with normal sC5b-9 levels and no proteinuria (Jodele S, et al. Blood. 2014;124:645-653). In the HSCT setting, toxic conditioning regimens, infection, and graft-versus-host disease (GVHD) can cause endothelial injury, which triggers activation of the lectin pathway of complement and in turn the coagulation cascade, together leading to TMA. Narsoplimab (OMS721) is a fully human IgG4 monoclonal antibody that inhibits mannan-binding lectin-associated serine protease-2 (MASP-2), the effector enzyme of the lectin pathway and an activator of the coagulation cascade. Narsoplimab was previously evaluated for safety and efficacy in adults with high-risk HSCT-TMA in an open-label pivotal trial (NCT02222545); narsoplimab treatment was well tolerated and resulted in clinical response and favorable overall survival (Khaled SK, et al. J Clin Oncol. 2022; JCO2102389). Currently, HSCT-TMA has no approved therapy, and therefore represents a significant unmet medical need. Here, we describe the design of the first clinical trial evaluating the efficacy and safety of narsoplimab in pediatric patients with HSCT-TMA. Study Design and Methods: This is an open-label, multi-center Phase 2 trial of narsoplimab in pediatric patients (Figure 1). Eligible patients are aged ≥28 days to <18 years, have received alloHSCT for the treatment of non-malignant or malignant disease, and have been diagnosed with high-risk HSCT-TMA. Exclusion criteria include prior treatment with eculizumab, ravulizumab, or defibrotide within 3 months prior to screening, having Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (STEC-HUS), or ADAMTS13 activity <10%. Patients will receive narsoplimab 4 mg/kg via intravenous (IV) infusion twice weekly during the 8-week treatment period (Days 1-56). If a patient meets all clinical response criteria prior to 8 weeks of treatment, dosing may be decreased to 4 mg/kg IV once weekly until the end of the treatment period. Narsoplimab can be used in conjunction with standard-of-care treatments. At the end of the treatment period, patients will enter a 44-week follow-up period (Days 60-365). The planned recruitment is at least 18 pediatric patients, distributed across the age range. The primary endpoint is 100-day survival from date of HSCT-TMA diagnosis. Secondary endpoints include: safety, survival at 52 weeks, overall survival from date of HSCT-TMA diagnosis, anti-drug antibody response, clinical response rate, narsoplimab pharmacokinetics and measurement of lectin pathway activity. Conclusion: Following the favorable results obtained in a pivotal Phase 2 study in adults with HSCT-TMA, further evaluation of narsoplimab efficacy and safety in pediatric patients with high-risk HSCT-TMA is warranted. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Augmenting the Persistence and Efficacy of Engineered Regulatory T Cells to Suppress Anti-Drug Antibody Formation

Background Adoptive cell therapy (ACT) using engineered antigen specific regulatory T cells (Tregs) is a powerful tool for delivering immune tolerance in autoimmune disease, transplantation and in suppressing undesirable anti-drug antibody (ADA) responses against therapeutic proteins. An important example of the latter is hemophilia A (HA), a genetic disorder characterized by deficiency of the blood clotting protein, factor VIII (FVIII). Replacement therapy with recombinant FVIII can be neutralized by ADA development in up to 30% of severe HA patients. We previously showed that ACT with Tregs expressing a chimeric CD3ε based T cell receptor fusion construct (TRuC), encoding extracellular antibody fragments with specificity to human FVIII, suppressed ADA formation to FVIII in a preclinical HA model [Mol Ther. 2021 29(9):2660-2676]. Ensuring adequate in vivo persistence and a suppressive phenotype without risk of plasticity are major concerns that impede translation of ACT with engineered Tregs. Here we evaluate a synthetic single chain antibody fusion IL2 cytokine product (IL2-IC) to selectively expand adoptively transferred FVIII-TRuC Tregs in vivo. We then combine IL2-IC delivery with FVIII-TRuC Tregs expressing the co-inhibitory receptor PD-L1 to test improved suppression to ADA formation. Methods IL2-IC was generated by fusing IL-2 cytokine to the anti-IL-2 monoclonal antibody F5111 via a flexible linker. This complex specifically delivers IL2 to cells that express high levels of IL2 receptor α (IL2Rα) (i.e., Tregs) while avoiding interaction with cells that express low levels (i.e., Tconv, NK and CD8+ T cells). To assess whether IL2-IC could expand TRuC Tregs in vivo, 2x106 FVIII TRuC Tregs were injected intravenously (IV) into HAmice followed 5 hrs later with low dose IL2-IC or IL2 fused to an irrelevant Ab (FITC-IC) as control. 24 hrs later, mice received 2 international units (IU) of FVIII, and spleens were assayed on days 3 and 6. Murine PD-L1 was co-expressed in FVIII TRuC Tregs and in vitro assessed by stimulating TRuC PDL1 Tregs with 2IU FVIII alone or in combination with 2 ug/ml of PD1-Fc to understand the impact of PDL1 signaling on the Treg phenotype. In vivo, 0.5x106 FVIII TRuC PD-L1 Tregs were IV injected in HAmice followed 5 hrs later by mock, IL2-IC or FITC-IC IV injections. 24 hrs later, mice received weekly IV injections of 1IU FVIII. Results IL2-IC treated FVIII TRuC Tregs were preferentially expanded over endogenous Tregs (fold expansion 7.47 vs 4.56 respectively) in spleens on day 3 post ACT. Whereas both IL2-IC and FITC-IC treated FVIII TRuC Tregs had higher division indices over mock treatment (4.047 ± 0.03 and 5.070 ± 0.07 over 2.00 ± 0.00), only IL2-IC treated FVIII TRuC Tregs showed increased frequencies (1.72% ± 0.376% of CD4+ T cells) as compared to FITC-IC (0.28% ± 0.005% of CD4+ T cells) or mock treatment (0.23% ± 0.023% of CD4+ T cells). FITC-IC treatment nonspecifically expanded CD8+ Tconv cells as well as NK cells, whereas IL2-IC selectively expanded Tregs. PD1-Fc triggered PD-L1 signals in FVIII stimulated TRuC Tregs resulted in significant upregulation of Treg associated activation markers FoxP3, CD69, LAP, CTLA4, PD1, ICOS and BCL2 in vitro. In vivo, IL2-IC administration combined with FVIII TRuC PD-L1 ACT led to complete suppression of ADA formation in HA mice. At 4 weeks, mice that only received FVIII infusions developed high functional ADA titers (29.53 ± 19.58 BU/mL), while IL2-IC, TRuC PDL1 Treg and TRuC PDL1 Treg + IL2-IC groups had significantly lower titers of 1.117 ± 0.952 BU/mL, 1.805 ± 0.702 BU/mL and 0.423 ± 0.243 BU/mL, respectively. FITC-IC combined with PDL1 TRuC Tregs resulted in high ADAs of average 109 ± 21.31 BU/mL, confirming the requirement for the IL2Rα targeting antibody to selectively expand Tregs. Conclusion We show that the PD-L1/PD1 axis is an important pathway that can be exploited to improve the suppressive capacity of engineered Tregs. We also demonstrate that exogenous administration of the novel IL2-IC can robustly expand FVIII TRuC Tregs. These 2 strategies can be readily combined to selectively expand and enhance the suppressive capacity of engineered Tregs. The concepts defined here can be extended for improving the persistence and suppressive potential of engineered Tregs for various autoimmune disorders and to prevent transplant rejection. We are currently evaluating long term suppression of ADA responses using this approach.

Determination of Anti-drug Antibody Affinity in Clinical Study Samples Provides a Tool for Evaluation of Immune Response Maturation

Characterization of clinical anti-drug antibody (ADA) responses to biotherapeutics can be important to understanding the consequences of immunogenicity. ADA are expected to be polyclonal, with composition and affinities that evolve over time. Measuring ADA binding affinity can be complicated by the polyclonal nature of response, residual drug in sample, and low ADA levels. We developed a novel workflow to determine the apparent ADA affinity (KD) against a monoclonal antibody biotherapeutic, PF-06480605. An affinity capture elution pre-treatment step was used to isolate ADA and remove residual drug interference from samples. Solution-phase equilibrium incubation was performed using drug and sample ADA as variable and fixed binding interactants, respectively. Unbound ADA concentration was measured using a Singulex Erenna ligand-binding assay (LBA) method. Apparent ADA KD values were calculated using a custom R Shiny algorithm. KD values determined for ADA positive samples showed good correlation with other immunogenicity parameters, including titers and neutralizing antibody (NAb) activity with a general increase in affinity over time, indicative of a maturing immune response. Time of onset of high affinity responses (KD < 100 pM) varied between patients, ranging from 16 to 24 weeks. Antibody responses appeared monophasic at earlier time points, trending towards a biphasic response with a variable transition time and general increase in proportion of high affinity ADA over time. Herein, we provide a novel, sensitive bioanalytical method to determine the KD of ADA in clinical samples. The observed decrease in ADA KD is consistent with evidence of a maturing immune response.Graphical

Efficacy of dupilumab in patients with uncontrolled, moderate-to-severe asthma recruited from Japanese centers in the phase 3 LIBERTY ASTHMA TRAVERSE study

BackgroundSafety and efficacy data for dupilumab beyond 1 year are lacking for patients from Japan with moderate-to-severe asthma. MethodsThe TRAVERSE open-label extension (OLE) study (NCT02134028) assessed the safety and efficacy of dupilumab 300 mg every 2 weeks up to 96 weeks in 2282 patients who completed a previous dupilumab asthma study. The primary endpoint was incidence of treatment-emergent adverse events (TEAEs). Secondary endpoints included annualized severe exacerbation rate and change from parent study baseline in pre-bronchodilator forced expiratory volume in 1 second (FEV1), asthma control, quality of life, and blood eosinophil levels. Anti-drug antibodies (ADA) were evaluated. We report results in 160 (7.8% of exposed population) patients recruited from Japanese centers with non-oral corticosteroid (OCS)-dependent asthma rolled over from two parent studies, and in subgroups with a type 2 inflammatory phenotype. ResultsTEAEs were consistent with the parent studies and the known safety profile of dupilumab. One patient permanently discontinued treatment due to TEAEs. Exacerbation rates remained low and were sustained to Week 96, as were improvements in pre-bronchodilator FEV1. Rapid, sustained improvements were observed in dupilumab-treated patients who previously received placebo in a parent study, while further improvements in exacerbation rates, asthma control, and asthma-related quality of life were observed in those continuing dupilumab. Blood eosinophil levels decreased progressively while on treatment. Treatment-emergent ADA responses were highest in patients who had previously received placebo. Efficacy results were consistent in patients with a type 2 phenotype. ConclusionsLong-term dupilumab treatment was well tolerated and efficacious in patients with non–OCS-dependent, moderate-to-severe asthma recruited from Japan.(Funded by Sanofi and Regeneron Pharmaceuticals, Inc.; ClinicalTrials.gov identifier, NCT02134028)

Anti-viral efficacy of a next-generation CD4-binding site bNAb in SHIV-infected animals in the absence of anti-drug antibody responses

SummaryBroadly neutralizing antibodies (bNAbs) against HIV-1 are promising immunotherapeutic agents for treatment of HIV-1 infection. bNAbs can be administered to SHIV-infected rhesus macaques to assess their anti-viral efficacy; however, their delivery into macaques often leads to rapid formation of anti-drug antibody (ADA) responses limiting such assessment. Here, we depleted B cells in five SHIV-infected rhesus macaques by pretreatment with a depleting anti-CD20 antibody prior to bNAb infusions to reduce ADA. Peripheral B cells were depleted following anti-CD20 infusions and remained depleted for at least 9 weeks after the 1st anti-CD20 infusion. Plasma viremia dropped by more than 100-fold in viremic animals after the initial bNAb treatment. No significant humoral ADA responses were detected for as long as B cells remained depleted. Our results indicate that transient B cell depletion successfully inhibited emergence of ADA and improved the assessment of anti-viral efficacy of a bNAb in a SHIV-infected rhesus macaque model.

GP2017-HCF, a high concentration formulation, demonstrates similar pharmacokinetics, immunogenicity and safety to GP2017, an approved adalimumab biosimilar

ABSTRACT Background GP2017 is an adalimumab biosimilar. The objective of this study is to compare the pharmacokinetics (PK) of GP2017 in its approved formulation and GP2017-high concentration formulation (HCF) in a randomized, double-blind, two-arm PK bridging study. Research design and methods Healthy male subjects received a single 40 mg subcutaneous injection of either GP2017-HCF (n = 162) or GP2017 (n = 168). PK, safety, and immunogenicity were assessed over 72 days post-injection. Results The 90% confidence intervals [CIs] of geometric mean ratios between GP2017-HCF and GP2017 for Cmax, AUC0-inf, AUC0-360 and AUC0-last were within the pre-defined margin of 0.80 to 1.25; thus, PK comparability between GP2017-HCF and GP2017 was demonstrated. Subgroup analysis of PK comparability by anti-drug antibody (ADA) subpopulation showed that the 90% CIs of geometric mean ratios between GP2017-HCF and GP2017 for Cmax, AUC0-inf, AUC0-360 and AUC0-last were within the margin of 0.80 to 1.25 in ADA-positive and ADA-negative subjects. The proportions of subjects with positive ADA responses and with neutralizing antibodies were comparable between the GP2017-HCF and GP2017 groups. GP2017-HCF and GP2017 were well tolerated, and there were no reports of deaths or other serious adverse events. Conclusion Results show PK comparability between GP2017-HCF and GP2017 and comparable safety and tolerability.

Impact of glycoengineering and antidrug antibodies on the anticancer activity of a plant-made lectin-Fc fusion protein.

Plants are an efficient production platform for manufacturing glycoengineered monoclonal antibodies and antibody-like molecules. Avaren-Fc (AvFc) is a lectin-Fc fusion protein or lectibody produced in Nicotiana benthamiana, which selectively recognizes cancer-associated high-mannose glycans. In this study, we report the generation of a glycovariant of AvFc that is devoid of plant glycans, including the core α1,3-fucose and β1,2-xylose residues. The successful removal of these glycans was confirmed by glycan analysis using HPLC. This variant, AvFcΔXF , has significantly higher affinity for Fc gamma receptors and induces higher levels of luciferase expression in an antibody-dependent cell-mediated cytotoxicity (ADCC) reporter assay against B16F10 murine melanoma cells without inducing apoptosis or inhibiting proliferation. In the B16F10 flank tumour mouse model, we found that systemic administration of AvFcΔXF , but not an aglycosylated AvFc variant lacking affinity for Fc receptors, significantly delayed the growth of tumours, suggesting that Fc-mediated effector functions were integral. AvFcΔXF treatment also significantly reduced lung metastasis of B16F10 upon intravenous challenge whereas a sugar-binding-deficient mutant failed to show efficacy. Lastly, we determined the impact of antidrug antibodies (ADAs) on drug activity in vivo by pretreating animals with AvFcΔXF before implanting tumours. Despite a significant ADA response induced by the pretreatment, we found that the activity of AvFcΔXF was unaffected by the presence of these antibodies. These results demonstrate that glycoengineering is a powerful strategy to enhance AvFc's antitumor activity.

Comparison of Titer and Signal to Noise (S/N) for Determination of Anti-drug Antibody Magnitude Using Clinical Data from an Industry Consortium

During biotherapeutic drug development, immunogenicity is evaluated by measuring anti-drug antibodies (ADAs). The presence and magnitude of ADA responses is assessed using a multi-tier workflow where samples are screened, confirmed, and titered. Recent reports suggest that the assay signal to noise ratio (S/N) obtained during the screening tier correlates well with titer. To determine whether S/N could more broadly replace titer, anonymized ADA data from a consortium of sponsors was collected and analyzed. Datasets from clinical programs with therapeutics of varying immunogenicity risk levels (low to high), common ADA assay platforms (ELISA and MSD) and formats (bridging, direct, solid-phase extraction with acid dissociation), and titration approaches (endpoint and interpolated) were included in the analysis. A statistically significant correlation between S/N and titer was observed in all datasets, with a strong correlation (Spearman’s r > 0.8) in 11 out of 15 assays (73%). For assays with available data, conclusions regarding ADA impact on pharmacokinetics and pharmacodynamics were similar using S/N or titer. Subject ADA kinetic profiles were also comparable using the two measurements. Determination of antibody boosting in patients with pre-existing responses could be accomplished using similar approaches for titer and S/N. Investigation of factors that impacted the accuracy of ADA magnitude measurements revealed advantages and disadvantages to both approaches. In general, S/N had superior precision and ability to detect potentially low affinity/avidity responses compared to titer. This analysis indicates that S/N could serve as an equivalent and in some cases preferable alternative to titer for assessing ADA magnitude and evaluation of impact on clinical responses.Graphical

Pre-existing Reactivity to an IgG4 Fc-Epitope: Characterization and Mitigation of Interference in a Bridging Anti-drug Antibody Assay

Twenty percent of baseline patient samples exhibited a pre-existing response in a bridging anti-drug antibody (ADA) assay for a human IgG4 monoclonal antibody (mAb) therapeutic. In some cases, assay signals were more than 100-fold higher than background, potentially confounding detection of true treatment-emergent ADA responses. The pre-existing reactivity was mapped by competitive inhibition experiments using recombinant proteins or chimeric human mAbs with IgG4 heavy chain regions swapped for IgG1 sequences. These experiments demonstrated that the majority of the samples had reactivity to an epitope containing leucine 445 in the CH3 domain of human IgG4. The pre-existing reactivity in baseline patient samples was mitigated by replacing the ADA assay capture reagent with a version of the drug containing a wild type IgG1 proline substitution at residue 445 without impacting detection of drug-specific, treatment-emergent ADA. Finally, purification on Protein G or anti-human IgG (H + L) columns indicated the pre-existing response was likely due to immunoglobulins in patient samples.Graphical abstract