Discrimination of Anti-drug Antibodies With Neutralizing Capacity in Infliximab- and Adalimumab-Treated Patients: Comparison of the Homogeneous Mobility Shift Assay and the Affinity Capture and Elution Assay

Evaluation of the Homogenous Mobility Shift Assay for Infliximab and Adalimumab Anti-drug Antibody Detection in the Clinical Laboratory

BACKGROUND

Detecting antidrug antibodies (ADAs) against infliximab or adalimumab is useful for therapeutic drug monitoring. Various ADA detection methods exist, and antibody titer is an output in some algorithms. Homogenous mobility shift assay (HMSA) measures relative ADA concentration and determines drug-ADA complex size in vitro. However, the relevance of complex size determination in drug monitoring remains unclear. Hence, the association between complex size, ADA concentration, and sample detectable neutralizing activity was evaluated.

METHODS

Sera from infliximab-treated and adalimumab-treated patients who tested positive for ADA in the National Screening Service were analyzed using 3 ADA assays. HMSA determined the relative ADA concentrations and complex sizes, competitive ligand-binding assay evaluated the sample neutralizing capacity, and enzyme-linked immunosorbent assay detected immunoglobulin (Ig)G4 ADA.

RESULTS

Most ADA-positive samples (>80%) formed drug-ADA dimer complexes, whereas 17% had dimer and multimer complexes, and 3% had multimeric complexes. Multimer presence had 100% positive predictive value for detectable neutralizing activity. ADA concentration and detectable neutralizing activity were moderately correlated (r = 0.65) in adalimumab-treated patients and strongly correlated (r = 0.81) in infliximab-treated patients. In adalimumab-treated patients, multimer presence was a stronger predictor of neutralizing activity than ADA concentration was, but not in infliximab-treated patients. However, in infliximab-treated patient samples, multimer presence revealed a distinct subset with high ADA concentrations, neutralizing activity, and IgG4 ADA.

CONCLUSIONS

Multimers detected using HMSA had a strong positive predictive value for competitive ligand-binding assay detectable neutralizing activity. Multimeric IgG4-containing ADA-drug complexes revealed a distinct subset of infliximab-treated patient samples, whose clinical relevance merits further investigation.

Relationship Between Adalimumab Concentrations, Antidrug Antibodies, and Disease Activity in Rheumatoid Arthritis: A Cross-Sectional Observational Study

OBJECTIVES

To determine the influence of patient characteristics and disease activity on adalimumab (ADA) concentrations; to assess the relationships between ADA concentrations, the presence of antidrug antibodies (ADAb), and disease activity in rheumatoid arthritis (RA); and to determine the association between cytokine concentrations and ADA concentrations.

METHODS

A cross-sectional study of people with RA receiving ADA for at least 4 weeks was undertaken. Disease activity was assessed by the Disease Activity Score in 28 joints (DAS28), with responders defined as DAS28 ≤ 3.2. Serum and plasma were obtained for ADA concentrations and ADAb, and a panel of cytokines were obtained for a subgroup. ADA concentrations were compared between demographic and clinical subgroups using ANOVA. The independent associations between clinical and demographic features were analyzed using a general linear model. Variables significantly associated with ADA concentrations from the univariate analyses were entered into multivariate analyses.

RESULTS

Of the 156 participants, 69.2% were female and the mean age was 57.4 (SD 12.7) years. Multivariate analysis revealed that higher C-reactive protein (P < 0.001) and higher weight (P < 0.004) were independently associated with lower ADA concentrations. ADA concentrations were higher in those with DAS28 ≤ 3.2 compared to those with DAS28 > 3.2 (median 10.8 [IQR 6.4-20.8] mg/L vs 7.1 [IQR 1.5-12.6] mg/L, P < 0.001). There was a significant negative correlation between interleukin 6 (IL-6) and ADA concentrations (r = -0.04, P < 0.01).

CONCLUSION

ADA concentration correlates negatively with markers of inflammatory disease activity in RA, including IL-6. ADA concentration in the range 5 to 7 mg/L over the dose interval are associated with better disease control.

Phenotypic spectrum in a family with a novel RAC2 p.I21S dominant-activating mutation

Objectives

Dominant-activating (DA) lesions in RAC2 have been reported in 18 individuals to date. Some have required haematopoietic stem cell transplantation (HSCT) for their (severe) combined immunodeficiency syndrome phenotype. We aimed to investigate clinical and cellular features of a kindred harbouring a novel variant in RAC2 p.Ile21Ser (I21S) to better understand DA lesions' phenotypic spectrum.

Methods

Clinical and immunological information was collated for seven living individuals from the same kindred with RAC2 p.I21S. We evaluated neutrophil morphology, RAC2 protein expression and superoxide production using freshly isolated neutrophils stimulated with phorbol-12-myristate-13-acetate (PMA) and N-formyl-MetLeuPhe (fMLP).

Results

Patient 1 (P1, aged 11, male) has a history of bacterial suppurative otitis media, viral and bacterial cutaneous infections. P1's siblings (P2, P3), mother (P4), maternal aunt (P5) and uncle (P6) have similar infection histories. P1's maternal cousin (P7) presented with Burkitt's lymphoma at age 9. All affected individuals are alive and none has required HSCT to date. They have chronic lymphopenia affecting the CD4+T and B-cell compartments. P1-3 have isolated reduction in IgM levels whereas the adults universally have normal immunoglobulins. Specific antibody responses are preserved. Affected individuals have neutrophil vacuolation, and their neutrophils have enhanced superoxide production compared to healthy controls.

Conclusion

RAC2 p.I21S is an activating variant causing notable morphological and functional abnormalities similar to other reported DA mutations. This novel variant expands the broad clinical phenotypic spectrum of RAC2 DA lesions, emphasising the need to tailor clinical management according to patients' disease phenotype and severity.

Four-year review of New Zealand laboratory infliximab and adalimumab concentration results indicating potential for improved dosing

A review of laboratory results across New Zealand for therapeutic drug monitoring (TDM) of infliximab and adalimumab concentrations and antidrug antibodies (ADAs) over 4 years was completed. Of 6591 results, the median serum concentration for infliximab was 5.7 mg/L and for adalimumab was 5.5 mg/L. Subtherapeutic drug concentrations (<7 mg/L) were measured in 54% of samples. Drug concentrations <2 mg/L were measured in 23% of samples, with ADAs detected in 51% of these. The high number of samples with subtherapeutic drug concentrations and common ADA detection is consistent with failing therapy but could also suggest that standard dosing is frequently too low for patients. These results reinforce the value of antitumour necrosis factor drug TDM in making decisions to adjust dosing or switch agents in patients taking infliximab and adalimumab.

Levels and in vitro functional effects of circulating anti-hinge antibodies in melanoma patients receiving the immune checkpoint inhibitor pembrolizumab

The efficacy of PD-1 monoclonals such as pembrolizumab can be modulated by the signals delivered via their Fc region. Tumour/inflammation associated proteases can generate F(ab')2 fragments of therapeutic monoclonals, and subsequent recognition of F(ab')2 epitopes by circulating anti-hinge antibodies (AHA) can then, potentially, link F(ab')2 binding to the target antigen with novel Fc signalling. Although elevated in inflammatory diseases, AHA levels in cancer patients have not been investigated and functional studies utilising the full repertoire of AHA present in sera have been limited. AHA levels in pembrolizumab treated melanoma patients (n = 23) were therefore compared to those of normal donors and adalimumab treated patients. A subset of melanoma patients and the majority of adalimumab patients had elevated levels of AHA reactive with F(ab')2 fragments of IgG4 anti-PD-1 monoclonals (nivolumab, pembrolizumab) and IgG1 therapeutic monoclonals (rituximab, adalimumab). Survival analysis was restricted by the small patient numbers but those melanoma patients with the highest levels (>75% percentile, n = 5) of pembrolizumab-F(ab')2 reactive AHA had significantly better overall survival post pembrolizumab treatment (p = 0.039). In vitro functional studies demonstrated that the presence of AHA+ sera restored the neutrophil activating capacity of pembrolizumab to its F(ab')2 fragment. Neither pembrolizumab nor its F(ab')2 fragments can induce NK cell or complement dependent cytotoxicity (CDC). However, AHA+ sera in combination with pembrolizumab-F(ab')2 provided Fc regions that could activate NK cells. The ability of AHA+ sera to restore CDC activity was more restricted and observed using only one pembrolizumab and one adalimumab patient serum in combination with rituximab- F(ab')2. This study reports the presence of elevated AHA levels in pembrolizumab treated melanoma patients and highlight the potential for AHA to provide additional Fc signaling. The issue of whether tumour associated proteolysis of PD-1 mAbs and subsequent AHA recognition impacts on treatment efficacy requires further study.

Therapeutic Drug Monitoring in Practice for Inflammatory Bowel Disease

PURPOSE OF REVIEW

To outline the development, rationale, and practical use of therapeutic drug monitoring in patients with inflammatory bowel disease.

RECENT FINDINGS

Therapeutic drug monitoring is traditionally discussed in terms of a proactive or reactive approach. However, these terms are not always consistently defined and can be confusing when translating research to clinical practice. Personalized approaches incorporating clinical context and precision medicine are emerging. Personalized therapeutic drug monitoring combines a structured and proactive strategy for monitoring biologic concentrations as well as identification of antidrug antibody development or subtherapeutic dosing in the setting of loss of response. Optimizing biologic therapy can improve outcomes and avoid loss of response. Why, when, and how we measure drug troughs and anti-drug antibodies is a moving target, though what is known is that the appropriate and evidence-based use of this practice prevents adverse events and improves outcomes in patients with inflammatory bowel disease.

A Systematic Review on the interest of Drug Tolerant assay in the monitoring of Inflammatory Bowel Disease

Many patients with inflammatory bowel disease (IBD) are treated with anti-tumor necrosis factor (TNF) therapies, of which infliximab (IFX) is most commonly used. Loss of response (LOR) to anti-TNF therapy due to immunogenic failure accounts for 20% of subsequent medical intervention and is defined, using a drug sensitive assay, as low or undetectable concentration of drug with high titers of anti-drug antibodies (ADAb). We performed a systematic review to investigate the use of a drug tolerant assay during both induction and maintenance to monitor patients treated with anti-TNFs. After the search on PubMed, 90 publications were reviewed. Most ADAb detection methods are drug sensitive, cannot detect ADAb in the presence of drug, and therefore cannot be used close to drug administration, when the drug concentration is too high. To overcome this major limitation, several drug-tolerant techniques have been developed and will be discussed in this review. Using drug-tolerant assays ADAb against infliximab (IFX) or adalimumab (ADM) can be detected during induction and predict primary non-response or LOR. Drug sensitive assays do not allow detection of ADAb during the induction phase as IFX or ADM concentration is typically high.

Assessment of immunogenicity and drug activity in patient sera by flow-induced dispersion analysis

Biopharmaceuticals have revolutionized the treatment of many diseases such as diabetes, cancer, and autoimmune disorders. These complex entities provide unique advantages like high specificity towards their target. Unfortunately, biopharmaceuticals are also prone to elicit undesired immunogenic responses (immunogenicity), compromising treatment efficacy as well as patient safety due to severe adverse effects including life threatening conditions. Current immunogenicity assays are hampered by immobilization procedures, complicated sample pre-treatment, or rely on cell-based methods which all prevent reliable and continuous monitoring of patients. In this work, we present Flow Induced Dispersion Analysis (FIDA) for assessment of immunogenicity and drug activity in serum samples from arthritis patients receiving adalimumab. FIDA is a first principle technique for size-based characterization of biomolecules and their complexes under biologically relevant conditions. The FIDA methodology rely on an absolute and quantitative readout (hydrodynamic radius) thus reducing the need for positive and negative controls. Here, FIDA is applied for evaluating active adalimumab in serum by studying the interaction with its target tumor necrosis factor alpha (TNF-α). We report proof of principle for a quantitative approach for stratifying patients exhibiting presence of neutralizing and non-neutralizing antibodies based on their individual drug activity pattern. Further, it can be applied to any biopharmaceutical having soluble drug targets and it holds potential in a companion diagnostics setting.

Approaches for the detection and analysis of anti-drug antibodies to biopharmaceuticals: A review

Antibody-based therapeutic agents and other biopharmaceuticals are now used in the treatment of many diseases. However, when these biopharmaceuticals are administrated to patients, an immune reaction may occur that can reduce the drug's efficacy and lead to adverse side effects. The immunogenicity of biopharmaceuticals can be evaluated by detecting and measuring antibodies that have been produced against these drugs, or anti-drug antibodies (ADAs). Methods for ADA detection and analysis can be important during the selection of a therapeutic approach based on such drugs and is crucial when developing and testing new biopharmaceuticals. This review examines approaches that have been used for ADA detection, measurement, and characterization. Many of these approaches are based on immunoassays and antigen binding tests, including homogeneous mobility shift assays. Other techniques that have been used for the analysis of ADAs are capillary electrophoresis, reporter gene assays, surface plasmon resonance spectroscopy, and liquid chromatography-mass spectrometry. The general principles of each approach will be discussed, along with their recent applications with regards to ADA analysis. This article is protected by copyright. All rights reserved.

Functional effects of immune complexes formed between pembrolizumab and patient-generated anti-drug antibodies

The PD-1-targeting IgG₄ antibody pembrolizumab has significant anti-tumor activity in a proportion of stage IV melanoma patients. A subset of patients develop anti-drug antibodies (ADA) which can form immune complexes (IC) with pembrolizumab. Although IC can induce powerful, Fc-mediated, immune-regulatory effects, their functional impact during pembrolizumab treatment is unclear. The functional effects of IC generated in vitro using pembrolizumab and patient-derived ADA was, therefore, investigated. Screening identified a patient whose trough serum samples from three treatment cycles contained both ADA with neutralizing activity and low levels of pembrolizumab. This patient responded well to therapy over 2 years and had ongoing, infusion-related, hypersensitivity reactions despite the later absence of detectable ADA. The components of IC were mimicked by forming a complex of pembrolizumab by absorption onto a solid phase with or without subsequent exposure to the ADA⁺ patient sera. Complexes comprised of pembrolizumab alone significantly inhibited TLR4 (LPS)-driven IL-10 production by PBMC and stimulated the generation of reactive oxygen species by granulocytes. In contrast, soluble and solid-phase F(ab´)2 fragments of pembrolizumab had no effect demonstrating the requirement for cross-linked Fc regions. IC containing pembrolizumab and ADA could additionally induce complement and NK activation. The results of this study demonstrate that, when oligomerized, the Fc region of pembrolizumab alone can provide immuno-regulatory signals. Furthermore, IC containing both pembrolizumab and patient-generated ADA can induce additional signals. These Fc-mediated signals may modulate both hypersensitivity reactions and anti-tumor responses associated with pembrolizumab therapy.

Infliximab and adalimumab concentrations and anti-drug antibodies in inflammatory bowel disease control using New Zealand assays

BACKGROUND

Therapeutic drug monitoring of anti-tumour necrosis factor (TNF) drugs and anti-drug antibodies (ADA) is now recommended in the treatment of inflammatory bowel disease. However, assay types and drug concentration thresholds are still debated.

AIM

To correlate inflammatory bowel disease activity in a New Zealand cohort with trough concentrations of infliximab and adalimumab, and ADA using locally developed competitive-binding enzyme-linked immunosorbent assays (ELISA) to establish threshold concentrations.

METHODS

Patients with ulcerative colitis (UC) and Crohn disease (CD) from Christchurch and Dunedin on anti-TNF drugs >12 weeks were enrolled. Trough blood samples were assayed for drug and ADA concentrations. Other data included quality of life, blood count, C-reactive protein, albumin, renal function and disease activity indices.

RESULTS

Of 103 patients, 53 were on infliximab (36 CD, 15 UC and 2 unclassified) and 50 adalimumab (48 CD and 2 UC). Median (range) infliximab and adalimumab concentrations were 10.5 (0-41) and 9.61 mg/L (0-30). CD remission, Crohn Disease Activity Index <150, correlated with infliximab and adalimumab concentration in CD (infliximab, P = 0.03; adalimumab, P = 0.04), with too few UC patients for analysis. Receiver operator curve analysis suggested a threshold value of 5.1 mg/L for distinguishing active disease from remission for infliximab and 7.3 mg/L for adalimumab in CD. Of 13 patients with infliximab <2 mg/L, 10 were ADA positive by homogeneous mobility shift assay (HMSA), including five with neutralising antibodies using ELISA. Of six with adalimumab <2 mg/L, three were ADA positive using HMSA, including one with neutralising antibodies.

CONCLUSION

Using the New Zealand ELISA assay, threshold concentrations of 5 mg/L for infliximab and 7 mg/L for adalimumab are suggested to aid dosing decisions, consistent with results internationally. Both neutralising (ELISA) and non-neutralising ADA (HMSA) are associated with low drug concentrations.