Anti-drug Antibodies Research Articles

Phase 1, first-in-human study of TYRP1-TCB (RO7293583), a novel TYRP1-targeting CD3 T-cell engager, in metastatic melanoma: active drug monitoring to assess the impact of immune response on drug exposure.

Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy. TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352). Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro. This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

Expected Spesolimab Plasma Exposure following Intravenous and Subcutaneous Dosing in Patients with Generalized Pustular Psoriasis

Introduction: Generalized pustular psoriasis (GPP) is a chronic, potentially life-threatening inflammatory skin disease characterized by widespread flares of sterile pustules. Spesolimab is a first-in-class anti-interleukin-36 receptor monoclonal antibody approved to treat GPP flares in adults via intravenous (IV) infusion. The aim of this study was to simulate the plasma pharmacokinetics (PK) of IV versus subcutaneous (SC) doses of spesolimab to compare drug exposure profiles and support dosing strategies in patients with GPP.
 Methods: A population PK model was developed using individual-level PK, anti-drug antibody, and covariate data from eighteen studies in which subjects were treated with IV or SC spesolimab.1 The resulting PK model was used to simulate concentration-time profiles following varying doses of IV and SC spesolimab. Peak plasma concentration (Cmax), time to peak plasma concentration (Tmax), and area under the curve (AUC) were summarized for each dose regimen.
 Results: Simulated spesolimab exposures demonstrated that the Cmax and AUC of the single dose 900 mg IV infusion consistently exceeded that of various single doses of SC spesolimab tested. A SC dose greater than two-fold higher would be required to attain a Cmax comparable to that of spesolimab 900 mg IV. The difference in exposure between the two administration routes was most pronounced in the first 2 weeks after administration. Slow absorption is expected with SC injection, with Tmax attained at later time points after SC dosing compared to immediately following the 90-minute infusion for IV dosing. Results were the same when simulating a two-dose regimen administered one week apart.
 Conclusions: PK simulations suggest that treatment with IV and SC spesolimab can result in differences in drug exposure in clinical practice. The immediate and high exposure of IV spesolimab compared with the lower exposure of SC spesolimab are supportive of IV dosing with spesolimab in acute GPP flare treatment vs SC dosing.

Cardio-Oncoimmunology: Cardiac Toxicity, Cardiovascular Hypersensitivity, and Kounis Syndrome.

Cancer therapy can result in acute cardiac events, such as coronary artery spasm, acute myocardial infarction, thromboembolism, myocarditis, bradycardia, tachyarrhythmias, atrio-ventricular blocks, QT prolongation, torsades de pointes, pericardial effusion, and hypotension, as well as chronic conditions, such as hypertension, and systolic and diastolic left ventricular dysfunction presenting clinically as heart failure or cardiomyopathy. In cardio-oncology, when referring to cardiac toxicity and cardiovascular hypersensitivity, there is a great deal of misunderstanding. When a dose-related cardiovascular side effect continues even after the causative medication is stopped, it is referred to as a cardiotoxicity. A fibrotic response is the ultimate outcome of cardiac toxicity, which is defined as a dose-related cardiovascular adverse impact that lasts even after the causative treatment is stopped. Cardiotoxicity can occur after a single or brief exposure. On the other hand, the term cardiac or cardiovascular hypersensitivity describes an inflammatory reaction that is not dose-dependent, can occur at any point during therapy, even at very low medication dosages, and can present as Kounis syndrome. It may also be accompanied by anti-drug antibodies and tryptase levels. In this comprehensive review, we present the current views on cardiac toxicity and cardiovascular hypersensitivity, together with the reviewed cardiac literature on the chemotherapeutic agents inducing hypersensitivity reactions. Cardiac hypersensitivity seems to be the pathophysiologic basis of coronary artery spasm, acute coronary syndromes such as Kounis syndrome, and myocarditis caused by cancer therapy.

Sensitive B-cell receptor repertoire analysis shows repopulation correlates with clinical response to rituximab in rheumatoid arthritis

BackgroundAlthough B-cell depleting therapy in rheumatoid arthritis (RA) is clearly effective, response is variable and does not correlate with B cell depletion itself.MethodsThe B-cell receptor (BCR) repertoire was prospectively analyzed in peripheral blood samples of twenty-eight RA patients undergoing rituximab therapy. Timepoints of achieved BCR-depletion and -repopulation were defined based on the percentage of unmutated BCRs in the repertoire. The predictive value of early BCR-depletion (within one-month post-treatment) and early BCR-repopulation (within 6 months post-treatment) on clinical response was assessed.ResultsWe observed changes in the peripheral blood BCR repertoire after rituximab treatment, i.e., increased clonal expansion, decreased clonal diversification and increased mutation load which persisted up to 12 months after treatment, but started to revert at month 6. Early BCR depletion was not associated with early clinical response but late depleters did show early response. Patients with early repopulation with unmutated BCRs showed a significant decrease in disease activity in the interval 6 to 12 months. Development of anti-drug antibodies non-significantly correlated with more BCR repopulation.ConclusionOur findings indicate that rather than BCR-depletion it is repopulation with unmutated BCRs, possibly from naïve B cells, which induces remission. This suggests that (pre-existing) differences in B-cell turnover between patients explain the interindividual differences in early clinical effect.

Biodistribution of Drug/ADA Complexes: The Impact of Immune Complex Formation on Antibody Distribution

The clinical use of therapeutic monoclonal antibodies (mAbs) for the treatment of cancer, inflammation, and other indications has been successfully established. A critical aspect of drug-antibody pharmacokinetics is immunogenicity, which triggers an immune response via an anti-drug antibody (ADA) and forms drug/ADA immune complexes (ICs). As a consequence, there may be a reduced efficacy upon neutralization by ADA or an accelerated drug clearance. It is therefore important to understand immunogenicity in biological therapies. A drug-like immunoglobulin G (IgG) was radiolabeled with tritium, and ICs were formed using polyclonal ADA, directed against the complementary-determining region of the drug-IgG, to investigate in vivo biodistribution in rodents. It was demonstrated that 65% of the radioactive IC dose was excreted within the first 24 h, compared with only 6% in the control group who received non-complexed 3H-drug. Autoradiographic imaging at the early time point indicated a deposition of immune complexes in the liver, lung, and spleen indicated by an increased radioactivity signal. A biodistribution study confirmed the results and revealed further insights regarding excretion and plasma profiles. It is assumed that the immune complexes are readily taken up by the reticuloendothelial system. The ICs are degraded proteolytically, and the released radioactively labeled amino acids are redistributed throughout the body. These are mainly renally excreted as indicated by urine measurements or incorporated into protein synthesis. These biodistribution studies using tritium-labeled immune complexes described in this article underline the importance of understanding the immunogenicity induced by therapeutic proteins and the resulting influence on biological behavior.Graphical Created with BioRender.com

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.

Intensive urate-lowering with pegloticase plus methotrexate co-therapy in uncontrolled gout patients with and without chronic kidney disease: A retrospective case series.

Chronic kidney disease (CKD) and gout commonly co-occur. Pegloticase lowers serum urate (SU) in uncontrolled gout patients but antidrug antibodies limit urate-lowering response and increase infusion reaction (IR) risk. Methotrexate (MTX) co-administration increases pegloticase response rate and mitigates IR risk but CKD limits MTX use. This pooled case series examined pegloticase + MTX co-therapy in uncontrolled gout patients with and without CKD. Cases of pegloticase + MTX co-therapy in existing datasets were retrospectively examined. Baseline eGFR classified patients as CKD (eGFR < 60 mL/min/1.73 m2) or non-CKD (eGFR ≥ 60 mL/min/1.73 m2). Patient characteristics, treatment parameters, laboratory values, urate-lowering response rate (≥12 pegloticase infusions received and SU < 6 mg/dL just before infusion 12), and AEs were examined. Fifteen CKD (eGFR: 43.2 ± 11.3 mL/min/1.73 m2; SU: 8.6 ± 2.2 mg/dL), 27 non-CKD (eGFR: 82.9 ± 19.0 mL/min/1.73 m2; SU: 9.5 ± 1.7 mg/dL) patients were included. Comorbidity profiles were similar, but CKD patients were older (72.0 ± 9.9 vs 52.3 ± 14.3 years) and more often female (33.3% vs 7.4%). Treatment parameters were similar with 4-week MTX Run-in followed by mean of 14.7 ± 8.1 [CKD] vs 14.1 ± 7.1 [non-CKD] pegloticase infusions. However, CKD patients had lower MTX dose (14.8 ± 5.8 vs 19.3 ± 4.9 mg/week). Urate-lowering response was similar (92% vs 86%). eGFR increased during treatment in 60% of CKD (+11.5 ± 20.9 mL/min/1.73 m2, 87% stable/improved CKD-stage) and 44% of non-CKD (+4.2 ± 15.0 mL/min/1.73 m2) patients. AEs were similar (≥1 AE CKD: 53%, non-CKD: 67%; gout flare most-reported). One case each of pancytopenia and IR (mild) occurred in non-CKD patients. These real-world data show similar pegloticase + MTX efficacy in CKD and non-CKD patients. No new safety signals were identified, with most CKD patients showing renal function stability or improvement during therapy.

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

Active immunotherapy for C5a-mediated inflammation using adjuvant-free self-assembled peptide nanofibers

The terminal protein in the complement cascade C5a is a potent inflammatory molecule and chemoattractant that is involved in the pathology of multiple inflammatory diseases including sepsis and arthritis, making it a promising protein to target with immunotherapies. Active immunotherapies, in which patients are immunized against problematic self-molecules and generate therapeutic antibodies as a result, have received increasing interest as an alternative to traditional monoclonal antibody treatments. In previous work, we have designed supramolecular self-assembling peptide nanofibers as active immunotherapies with defined combinations of B- and T-cell epitopes. Herein, the self-assembling peptide Q11 platform was employed to generate a C5a-targeting active immunotherapy. Two of three predicted B-cell epitope peptides from C5a were found to be immunogenic when displayed within Q11 nanofibers, and the nanofibers were capable of reducing C5a serum concentrations following immunization. Contrastingly, C5a's precursor protein C5 maintained its original concentration, promising to minimize side effects heretofore associated with C5-targeted therapies. Immunization protected mice against an LPS-challenge model of sepsis, and it reduced clinical severity in a model of collagen-antibody induced arthritis. Together, this work indicates the potential for targeting terminal complement proteins with active immunotherapies by leveraging the immunogenicity of self-assembled peptide nanomaterials. Statement of significanceChronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and inflammatory bowel disease are currently treated primarily with monoclonal antibodies against key inflammatory mediators. While helpful for many patients, they have high non-response rates, are costly, and commonly fail as anti-drug antibodies are raised by the patient. The approach we describe here explores a fundamentally different treatment paradigm: raising therapeutic antibody responses with an active immunotherapy.We employ innovative supramolecular peptide nanomaterials to elicit neutralizing antibody responses against complement component C5a and demonstrate therapeutic efficacy in preclinical mouse models of sepsis and rheumatoid arthritis. The strategy reported may represent a potential alternative to monoclonal antibody therapies.

Overcoming provider barriers to therapeutic drug monitoring of tumour necrosis factor inhibitors for rheumatoid arthritis: a qualitative analysis.

Therapeutic drug monitoring (TDM) of tumour necrosis factor-α inhibitors (TNFi), by measuring drug levels and/or anti-drug antibodies, is being considered by various international bodies to improve patient health outcomes and the value of care for people with rheumatoid arthritis. Rheumatology care providers may perceive barriers to adopting TNFi TDM within their own clinical practice, limiting the potential for patients and health care systems to benefit. This study aimed to explore the barriers perceived by rheumatologists that may reduce their uptake of TNFi TDM for rheumatoid arthritis. Semi-structured one-to-one telephone interviews were performed with a convenience sample of senior rheumatologists with experience of managing people with rheumatoid arthritis. The interviews explored the rheumatologists' understanding of TDM and their beliefs about how it can be integrated into their own routine practice. Interviews were audio recorded, transcribed verbatim and anonymized. Transcripts were coded inductively and barriers to using TNFi TDM were identified by thematic framework analysis. A sample of eleven senior rheumatologists were interviewed. The rheumatologists described five barriers to adopting TNFi TDM in routine practice: (i) observing clinical need; (ii) understanding how testing can improve practice; (iii) insufficient clinical evidence; (iv) insufficient resources to pay for testing; and (v) insufficient capability to deliver testing. Barriers to adopting TNFi TDM in routine care settings will restrict the ability for patients to benefit from effective monitoring strategies as they begin to emerge. Strategies to overcome these barriers are suggested which will require a coordinated response from stakeholders across health care systems.

First-in-human Study With LIS1, a Next-generation Porcine Low Immunogenicity Antilymphocyte Immunoglobulin in Kidney Transplantation.

Polyclonal rabbit antithymocyte globulins (ATGs) are commonly used in organ transplantation as induction. Anti- N -glycolylneuraminic acid carbohydrate antibodies which develop in response to rabbit carbohydrate antigens might lead to unwanted systemic inflammation. LIS1, the first new generation of antilymphocyte globulins (ALGs) derived from double knockout swine, lacking carbohydrate xenoantigens was already tested in nonhuman primates and rodent models. This open-label, single-site, dose escalation, first-in-human, phase 1 study evaluated the safety, T cell depletion, pharmacokinetics, and pharmacodynamics of LIS1. In an ascending dose cohort (n = 5), a primary kidney transplant recipient at low immunologic risk (panel reactive antibody [PRA] < 20%), received LIS1 for 5 d at either 0.6, 1, 3, 6, or 8 mg/kg. After each patient completed treatment, the data safety monitoring board approved respective dose escalation. In the therapeutic dose cohort (n = 5) in patients with PRA <50% without donor specific antibodies, 2 patients received 8 mg/kg and 3 patients 10 mg/kg. CD3 + T cell depletion <100/mm 3 at day 2 was observed in all patients who received 6, 8, and 10 mg/kg of LIS1. The terminal half-life of LIS1 was 33.7 d with linearity in its disposition. Lymphocyte repopulation was fast and pretransplant lymphocyte subpopulation counts recovered within 2-4 wk. LIS1 was well tolerated, neither cytokine release syndrome nor severe thrombocytopenia or leukopenia were noticed. Antibodies to LIS1 were not detected. In this first-in-human trial, genome-edited swine-derived polyclonal LIS1 ALG was well tolerated, did not elicit antidrug antibodies, and caused time-limited T cell depletion in low- and medium-risk kidney transplant recipients.

Immunogenicity of avelumab in patients with metastatic Merkel cell carcinoma or advanced urothelial carcinoma.

Like other monoclonal antibodies, immune checkpoint inhibitors may be immunogenic in some patients, potentially affecting pharmacokinetics (PKs) and clinical outcomes. In post hoc analyses, we characterized antidrug antibody (ADA) development with avelumab monotherapy in patients with metastatic Merkel cell carcinoma (mMCC) from the JAVELIN Merkel 200 trial (first-line [1L; N = 116] and second-line or later [≥2L; N = 88] cohorts) or with advanced urothelial carcinoma (aUC) from the JAVELIN Bladder 100 (1L maintenance [N = 350]) and JAVELIN Solid Tumor (≥2L [N = 249]) trials. Treatment-emergent ADAs developed in a numerically higher proportion of patients with aUC (1L maintenance, 19.1%; ≥2L, 18.1%) versus mMCC (1L, 8.2%; ≥2L, 8.9%); incidences within tumor types were similar by line of therapy. In PK analyses, numerically lower avelumab trough concentration and higher baseline clearance were observed in treatment-emergent ADA+ versus ADA- subgroups; however, differences were not clinically relevant. Numerical differences in overall survival, progression-free survival, or objective response rate by ADA status were observed; however, no clinically meaningful trends were identified. Proportions of patients with treatment-emergent adverse events (TEAEs; any grade or grade 3/4), serious TEAEs, TEAEs leading to treatment discontinuation, or infusion-related reactions were similar, with overlapping 80% confidence intervals between ADA subgroups. Efficacy and safety observations were similar in subgroups defined by early development of ADA+ status during treatment. In conclusion, no meaningful differences in PKs, efficacy, and safety were observed between subgroups of avelumab-treated patients with different ADA status. Overall, these data suggest that ADAs are not relevant for treatment decisions with avelumab.

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.

Immunogenicity and Loss of Effectiveness of Biologic Therapy for Inflammatory Bowel Disease Patients Due to Anti-Drug Antibody Development.

Many patients with inflammatory bowel disease (IBD) experience a loss of effectiveness to biologic therapy (i.e., anti-TNF therapy, etc.). Therefore, in addition to the adverse effects of the treatment, these patients also face failure to achieve and maintain remission. Immunogenicity, the process of production of antibodies to biological agents, is fundamental to the evolution of loss of response to treatment in IBD patients. The presence of these antibodies in patients is linked to decreased serum drug levels and inhibited biological activity. However, immunogenicity rates exhibit significant variability across inflammatory disease states, immunoassay formats, and time periods. In this review, we aimed to elucidate the immunogenicity and immune mechanisms of antibody formation to biologics, the loss of therapy response, clinical results of biological treatment for IBD from systematic reviews and meta-analyses, as well as to summarize the most recent strategies for overcoming immunogenicity and approaches for managing treatment failure in IBD.

An observer-blind, randomised, placebo-controlled, phase 1, single ascending dose study of dengue monoclonal antibody in healthy adults in Australia

Dengue is highly prevalent in Asia and Latin America and has no specific dengue antiviral treatment. A recombinant monoclonal antibody (VIS513) that neutralises all four serotypes of the dengue virus has been developed in India. After confirmation of safety and efficacy in preclinical studies, it was tested in a first-in-human study to assess the safety and pharmacokinetics. This was a partially blind (observer-blind), randomised, placebo-controlled, phase 1, single ascending dose study in Australia. Participants were dengue naive, healthy adults (aged 18-45 years) with no clinically significant disorders or immunosuppressive conditions. Four dose levels of dengue monoclonal antibody (ie, 1 mg/kg, 3 mg/kg, 7 mg/kg, and 12 mg/kg; n=4 for 1 mg/kg and n=10 each for 3 mg/kg, 7 mg/kg, and 12 mg/kg doses) were assessed in a dose-ascending way with a placebo control (n=2 for each dose cohort, total n=6) for each cohort except for 1 mg/kg. Within each cohort, participants were first randomly assigned (1:1) in a sentinel sub-cohort and then randomly assigned (9:1) in an expansion sub-cohort to dengue monoclonal antibody or placebo except for the 1 mg/kg cohort. Participants, investigators, and outcome assessors were masked and treatment administrators were not masked. 40 participants received a single intravenous injection or infusion of either dengue monoclonal antibody or placebo over a period of 3 min to 2 h and were followed up until day 85. The primary outcomes were proportion of participants with adverse events and serious adverse events (SAEs) up to 84 days after dosing whereas the secondary outcomes were to assess the pharmacokinetic profile of dengue monoclonal antibody and to assess the presence of anti-drug antibody (ADA) to dengue monoclonal antibody. All participants were included in the safety analysis and the pharmacokinetic population involved participants receiving dengue monoclonal antibody. This study is registered with ClinicalTrials.gov, NCT03883620. Between March 22 and Dec 23, 2019, 40 healthy adults were randomly assigned and all completed the study. There were no SAEs reported. None of the placebo recipients (n=6) reported any adverse events. 31 (91%) of 34 participants receiving dengue monoclonal antibody reported 143 adverse events (1 mg/kg: four [100%] of four participants; 3 mg/kg: ten [100%] of ten participants; 7 mg/kg: seven [70%] of ten participants; 12 mg/kg: ten [100%] of ten participants). Of these 143 adverse events, 80 were treatment-related adverse events in 28 (82%) of 34 participants. Headache (16 [47%] of 34), infusion reaction (11 [32%] of 34), lymphopenia (seven [21%] of 34), fatigue (five [15%] of 34), and pyrexia (four [12%] of 34) were the most common reactions. Infusion reactions were reduced in the 7 mg/kg (two [20%] of ten participants) and 12 mg/kg (three [30%] of ten) cohorts with paracetamol premedication compared with the 3 mg/kg cohort (five [50%] of ten). The majority of adverse events were grade 1 or grade 2 in severity, and resolved completely. Median maximum serum concentrations ranged from 28 μg/mL (1 mg/kg) to 525 μg/mL (12 mg/kg). The median elimination half-life ranged from 775 h (1 mg/kg) to 878 h (12 mg/kg). No ADA against dengue monoclonal antibody was detected. Dengue monoclonal antibody was safe and well tolerated. It showed a dose-proportionate increase in pharmacokinetic exposure. These data support further evaluation of dengue monoclonal antibody in patients with dengue for safety and efficacy. Serum Institute of India.

Clinical consequences of infliximab immunogenicity and the effect of proactive therapeutic drug monitoring: exploratory analyses of the randomised, controlled NOR-DRUM trials

Antidrug antibodies to TNF inhibitors might affect clinical outcomes. Proactive therapeutic drug monitoring allows for early detection of antidrug antibodies and might reduce negative clinical consequences. We aimed to explore how antidrug antibodies to the TNF inhibitor infliximab influence treatment outcomes, and to assess the effect of proactive therapeutic drug monitoring. This was a predefined exploratory analysis of data from the randomised, controlled NOR-DRUM trials. The trials were conducted in rheumatology, gastroenterology, and dermatology departments at 21 Norwegian hospitals. Adult patients (aged 18-75 years) with immune-mediated inflammatory diseases were randomly assigned to proactive therapeutic drug monitoring or standard infliximab dosing in the NOR-DRUM A trial (30-week follow-up) and the NOR-DRUM B trial (52-week follow-up). Antidrug antibodies were assessed with a drug-sensitive assay before each infusion. The outcomes of remission (at week 30), disease worsening (during 52 weeks), infusion reactions, and infliximab discontinuation were assessed according to the presence of antidrug antibodies and use of therapeutic drug monitoring. Between March 1, 2017, and Dec 12, 2019, 616 patients were included in the NOR-DRUM trials, of whom 615 had at least one serum infliximab and antidrug antibody assessment and were included in the present analyses. Mean age was 45 years (IQR 32-56), 305 (50%) patients were women, and 310 (50%) patients were men. Antidrug antibodies were detected in 147 (24%) patients. Remission at week 30 occurred in 25 (35%) of 72 patients with antidrug antibodies and 180 (54%) of 335 without antidrug antibodies (risk ratio 0·62 [95% CI 0·45-0·86]; p=0·0037). In patients with antidrug antibodies compared with patients without antidrug antibodies, higher rates were found for: disease worsening over 52 weeks (0·76 per person-year vs 0· 35 per person-year, hazard ratio [HR] 2·02 [95% CI 1·33-3·07]; p=0·0009), infusion reactions (0·16 per person-year vs 0·03 per person-year, HR 17·02 [6·98-41·47]; p<0·0001), and infliximab discontinuation (1·00 per person-year vs 0·20 per person-year, HR 6·64 [4·84-9·11]; p<0·0001). These associations were more pronounced in patients with high concentrations of antidrug antibodies than in those with low concentrations of antidrug antibodies. Independent of antibody status, therapeutic drug monitoring was associated with a lower risk of disease worsening (HR 0·41 [0·29-0·59]; p=0·0001) or an infusion reaction (HR 0·30 [0·12-0·73]; p=0·0076), and was associated with an increase in the rate of infliximab discontinuation (HR 1·37 [1·02-1·83]; p=0·037). In patients where antidrug antibodies were detected, remission was less likely to be reached and sustained, and infusion reaction or discontinuation of infliximab was more likely. Timely detection of antidrug antibodies by proactive therapeutic drug monitoring facilitated treatment decisions that reduced the negative consequences, both regarding infliximab effectiveness and safety. This highlights the role of proactive therapeutic drug monitoring in optimising infliximab therapy. Inter-regional KLINBEFORSK grants and South-Eastern Norway Regional Health Authority grants.

Experimental Validation a Method for Assessing Neutralizing Antibodies of Romiplostim in Human Plasma

Introduction. Romiplostim is an analogue of the fusion protein peptide of thrombopoietin (TPO), which increases platelet count by binding and activating the human thrombopoietin receptor (TPO-R). It is used to treat thrombocytopenia associated with chronic immune thrombocytopenia. For romiplostim, one of the possible adverse reactions from the immune system is immunogenicity: the production of anti-drug antibodies to the medicinal product, including neutralising antibodies, which may affect the efficacy and safety profile of the medicinal product.Aim. Validate the procedure for determining neutralising antibodies to romiplostim in human plasma for further clinical studies of immunogenicity.Materials and methods. The study used rabbit polyclonal antibodies to romiplostim, Nplate® produced by Amgen Europe as a standard sample; a placebo produced by LLC "GEROPHARM", a cell line 32D-hTPOR clone 63 with stable expression of human TPO receptor and a chemiluminescence assay kit CellTiter-Glo® Luminescent Cell Viability Assay produced by Promega to assess specificity. The experiment was carried out on cell line 32D-hTPOR clone 63, which was seeded on the first day and the neutralizing antibody concentrations were titrated with a constant concentration of romiplostim, then the chemiluminescence was detected on the second day. Statistical processing of the results was carried out using Prism 9 software.Result and discussion. The specificity of the procedure was demonstrated; at maximum concentration, the medicinal product differs from placebo by 309 times in the residual level of cell viability. The linearity of the procedure in terms of the coefficient determination is 0.9969. The precision of the procedure was determined: the repeatability was 1–9 %, the intermediate precision was 3–18 %. The coefficient of variation in selectivity of the procedure was 22 %. For the accuracy parameter, the values for recovery/spike were determined as 90–101 %. It was proven that there was no matrix effect.Conclusion. It can be stated that the procedure is linear, specific, highly precise, correct, selective and with a proven absence of matrix effect, which allows it to be used to determine the immunogenicity of romiplostim medicinal products in clinical studies.

Development and Validation of the Cell-based Functional Method for Neutralizing Anti-adalimumab Antibodies Detection in Human Serum

Introduction. Adalimumab, a fully humanized monoclonal antibody, is a tumor necrosis factor (TNFα) inactivator that is used against a number of autoimmune diseases such as rheumatoid arthritis and other most common inflammatory arthropathies (ankylosing spondylitis, psoriatic arthritis). Despite the proven efficacy of adalimumab treatment, there is a risk of adverse events, tied up with the formation of anti-drug antibodies, including neutralizing antibodies. Currently, the evaluation and characterization of neutralizing antibodies has become an important part of clinical trials in the development of new drugs and biosimilars.Aim. The aim of this study is to develop and validate the cell-based functional method for neutralizing anti-adalimumab antibodies determination in human serum.Materials and methods. For determination of neutralizing anti-adalimumab antibodies, the cell line L-929 has been employed. L-929 is a cell line sensitive to the TNFα-mediated apoptosis; the neutralizing antibodies interact with adalimumab that leads to TNFα-mediated cytotoxicity. Cytotoxicity was measured using resazurin, an aromatic compound that is a redox indicator.Results and discussion. The developed method was validated for cut point, selectivity, sensitivity, precision, specificity and stability (short- and long-term). An important part of a method development for determining neutralizing antibodies is the selection of concentrations of TNFα (4 ng/ml) and adalimumab (250 ng/ml), as well as determining the minimum required dilution – this parameter is established as 1 : 20. Cut point was chosen as a «floating» cut point, and a correction factor (normalization factor) was determined equal to 0,86. The sensitivity of the developed method was estimated at 108,9 ng/ml of neutralizing anti-adalimumab antibodies.Conclusion. The obtained results can be applied for determining anti-adalimumab neutralizing antibodies in the assessment of the adalimumab immunogenicity, including clinical trials.

A221 AZATHIOPRINE DOSING THRESHOLD IN ANTI-TNF COMBINATION THERAPY FOR MINIMIZING IMMUNOGENICITY AND OPTIMIZING TREATMENT EFFICACY FOR PATIENTS WITH INFLAMMATORY BOWEL DISEASE. A RETROSPECTIVE COHORT STUDY

Abstract Background Reported rates of anti-drug antibody (ADA) formation to tumor necrosis factor-a antagonists (anti-TNF) range from 20-75%. One way to reduce the risk of ADA formation is to combine a second immune-suppressing agent such as azathioprine (AZA) with the anti-TNF agent, known as combination therapy. However, it is unknown if the risk of combination therapy, including the additive risk of AZA and anti-TNF side effects, could be reduced by exposing individuals with inflammatory bowel disease (IBD) to the lowest dose of azathioprine while still maintaining the beneficial effect of ADA prevention. Aims To identify the minimum dose of AZA needed to prevent ADA formation to anti-TNF agents in individuals with IBD receiving combination therapy. We also assessed the occurrence of adverse drug events, treatment loss of response, treatment discontinuation and the need for treatment dose escalation. Methods A retrospective cohort study is ongoing in adult participants with IBDreceiving either infliximab or adalimumab in combination with AZA. Patients are divided based on their AZA dosage (low dose group, AZA ampersand:003C2mg/kg/day versus standard dose group, AZA 2mg/kg/day). All participants will be followed for 1 year and observed for the occurrence of ADA formation, adverse drug events, treatment loss of response, treatment discontinuation and the need for treatment dose escalation. Results To date, 48 participants are currently included (low dose, n=29; standard dose, n=19). 42 are on Infliximab and 6 are on Adalimumab. The occurrence of ADA was 17.4% in the low dose group and 20% in the standard dose group (pampersand:003E0.99). More participants lost response to treatment and discontinued anti-TNF therapy in the standard dose group (n=7/19, 36.8%) versus the low-dose group (n=8/29, 27.6%, p=0.54). More participants in the low-dose group received anti-TNF dose escalation (n= 20/29,68.9%) compared to the standard dose group (n=6/19, 31.6%, p=0.017). Adverse events, to Anti-TNF was seen in (n=3/19, 15.7%) in the standard dose group, in comparison to (n=4/29, 13.79%, pampersand:003E0.99) in the low dose group. Adverse events to AZA were surprisingly higher in the low dose group (n=14/29, 48.3%) while in the standard dose, it was (n=5/19, 26.3%, p=0.14). Conclusions The preliminary result of the study suggests that there is no significant difference in anti-drug antibody formation between standard and low doses of azathioprine in combination with anti-TNF therapy, in addition, data showed significant lower rates of Anti-TNF discontinuation and loss of response to treatment in low Azathioprine dose group. Completion of the study will help further define if low-dose AZA can be used for ADA prevention in anti-TNF combination therapy without compromising important clinical outcomes. Funding Agencies None

Infliximab desensitization in patients with inflammatory bowel diseases: a safe therapeutic alternative

Background Hypersensitivity reactions (HSR) to the administration of infliximab (IFX) in Inflammatory Bowel Diseases (IBD) patients are not rare and usually lead to drug discontinuation. We report data on safety and effectiveness of desensitization to IFX in patients with previous HSR. Methods We conducted a retrospective monocentric observational study. Patients for whom a desensitization protocol to IFX was realized after a previous HSR were included. Anti-drug antibodies (ADA) and IFX trough levels at both inclusion and six months after desensitization were collected. Clinical outcomes, including recurrence of HSR were evaluated. Results From 2005 to 2020, 27 patients (Crohn’s Disease: 26 (96%) were included). Desensitization after HSR was performed after a median time of 10.4 months (2.9-33.1). Nineteen (70%) patients received immunosuppressants at time of desensitization. Eight (30%) patients presented HSR at first (n = 2), second (n = 4) or third (n = 2) IFX perfusion after desensitization. None led to intensive care unit transfer or death. Thirteen (48%) had clinical response at 6 months and 8 (29%) were still under IFX treatment two years after desensitization. IFX trough levels and ADA were available for 14 patients at time of desensitization. Most patients (12 out of 14) had ADA at a high level. At 6 months, among the 7 patients with long term response to IFX, 4 presented a decrease of ADA titers and 2 had a significant trough level of IFX. Conclusion IFX desensitization in patients with IBD is a safe therapeutic alternative and represents a potential option for patients refractory to multiple biologics. What is already known? Hypersensitivity reactions to the administration of infliximab is frequent. Occurrence of hypersensitivity reaction, either immediate or delayed, usually leads to permanent drug discontinuation. What is new here? Infliximab desensitization is well tolerated with no hypersensitivity reaction recurrence in 70% of patients. Clinical success at 6 months was of 48% and around a third of patients remained under infliximab therapy two years after desensitization. Antidrug antibodies decreased and infliximab trough levels increased in these patients showing the impact of desensitization on immunogenicity. How can this study help patient care? Infliximab desensitization represents a potential option for patients refractory to multiple biologics who presented hypersensitivity reaction to the drug.