Neutropenia in Cynomolgus Monkeys With Anti-Drug Antibodies Associated With Administration of Afucosylated Humanized Monoclonal Antibodies

Removal of the core fucose from the Fc region of humanized monoclonal antibodies (afucosylated antibodies) enhances their antibody-dependent cell cytotoxicity activities in killing cancer cells. Based on the authors' experience and literature, administrations of afucosylated antibodies have been associated with neutropenia in cynomolgus monkeys. However, in a recent general toxicology study conducted with an afucosylated antibody in cynomolgus monkeys, transient neutropenia was observed and correlated with the emergence of anti-drug antibodies (ADAs) in the affected animals. To further explore the relationship between neutropenia, afucosylated antibodies, and ADAs in cynomolgus monkeys, we performed an investigational retrospective meta-analysis of data from general toxicology studies conducted with Genentech's therapeutic antibodies administered to cynomolgus monkeys between 2005 and 2021. In this analysis, transient neutropenia strongly correlated with ADA-induced inflammation in cynomolgus monkeys administered afucosylated antibodies. This may reflect the simultaneous occurrence of two distinct processes of neutrophil elimination and utilization, thus overwhelming bone marrow reserve capacity leading to transient neutropenia. The integrated analysis of immunogenicity, and anatomic and clinical pathology results from these studies highlights the correlation of transient neutropenia in cynomolgus monkeys with ADA-related inflammation, potentially exacerbated by enhanced effector function of afucosylated antibodies.

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.

Anti-adalimumab Antibodies in Patients with Non-infectious Ocular Inflammatory Disease: A Case Series

PURPOSE

To report the clinical course of patients with ocular inflammatory disease treated with adalimumab in whom anti-adalimumab antibodies (AAA) were detected.

METHODS

Single center case series.

RESULTS

Eight patients with initial response to adalimumab developed a disease flare associated with positive AAA testing after 5 to 76 months of therapy. Six patients were receiving no concurrent antimetabolite therapy at the time of AAA diagnosis and four had a temporary lapse in adalimumab therapy prior to AAA discovery. AAA resulted in undetectable drug levels in five of the seven patients for whom data were available, and adalimumab was discontinued in six of the eight patients. Of two patients continued on adalimumab, one maintained detectable serum adalimumab despite AAA and one had a low AAA titer.

CONCLUSIONS

For patients receiving adalimumab for ocular inflammatory disease, a disease flare in the setting of previously well-controlled disease should prompt consideration of AAA testing.

Pre-existing anti-drug antibodies in Fabry disease show less affinity for pegunigalsidase alfa

We analyzed the cross-reactivity of anti-drug antibodies (ADAs) against agalsidase-alfa and -beta from 49 patients with Fabry disease (FD) against the novel PEGylated enzyme pegunigalsidase-alfa (PRX-102). The affinity of purified anti-AGAL antibodies from pooled patient sera was significantly lower for PRX-102 compared to agalsidase-alfa and -beta (both p < 0.05). Pull-down experiments revealed the presence of masked epitopes on PRX-102, possibly due to PEGylation. ADA titers in serum (μg/mL) and corresponding inhibitory capacities against agalsidase-alfa and -beta were measured in male patients with FD, showing strong correlations (r² = 0.9978 and 0.4930, both p < 0.001). Affinities of ADAs of individual patients against PRX-102 (K_d: 3.55 ± 2.72 μmol) were significantly lower compared to agalsidase alfa (K_d: 1.99 ± 1.26 μmol) and -beta (K_d: 2.18 ± 1.51 μmol) (both p < 0.0001). Cross-ELISAs supported the presence of masked epitopes on PRX-102. Importantly, inhibition measurements also revealed a 30% reduction in inhibitory capacity of pre-existing ADAs towards PRX-102. Enzyme-uptake experiments in AGAL-deficient EA.hy926 cells demonstrated less effects of ADAs on cellular PRX-102 uptake compared with agalsidase beta. We conclude that due to the reduced affinity of pre-existing ADAs against agalsidase-alfa or -beta, ADA-affected patients might benefit from a therapy switch to PRX-102, which is currently evaluated in clinical trials.

Engineering a Therapeutic Protein to Enhance the Study of Anti-Drug Immunity

The development of anti-drug antibodies represents a significant barrier to the utilization of protein-based therapies for a wide variety of diseases. While the rate of antibody formation can vary depending on the therapeutic employed and the target patient population receiving the drug, the antigen-specific immune response underlying the development of anti-drug antibodies often remains difficult to define. This is especially true for patients with hemophilia A who, following exposure, develop antibodies against the coagulation factor, factor VIII (FVIII). Models capable of studying this response in an antigen-specific manner have been lacking. To overcome this challenge, we engineered FVIII to contain a peptide (323-339) from the model antigen ovalbumin (OVA), a very common tool used to study antigen-specific immunity. FVIII with an OVA peptide (FVIII-OVA) retained clotting activity and possessed the ability to activate CD4 T cells specific to OVA323-339 in vitro. When compared to FVIII alone, FVIII-OVA also exhibited a similar level of immunogenicity, suggesting that the presence of OVA323-339 does not substantially alter the anti-FVIII immune response. Intriguingly, while little CD4 T cell response could be observed following exposure to FVIII-OVA alone, inclusion of anti-FVIII antibodies, recently shown to favorably modulate anti-FVIII immune responses, significantly enhanced CD4 T cell activation following FVIII-OVA exposure. These results demonstrate that model antigens can be incorporated into a therapeutic protein to study antigen-specific responses and more specifically that the CD4 T cell response to FVIII-OVA can be augmented by pre-existing anti-FVIII antibodies.

A Genetic Association Test Accounting for Skewed X-Inactivation With Application to Biotherapy Immunogenicity in Patients With Autoimmune Diseases

Despite being assayed on commercialized DNA chips, the X chromosome is commonly excluded from genome-wide association studies (GWAS). One of the reasons is the complexity to analyze the data taking into account the X-chromosome inactivation (XCI) process in women and in particular the XCI process with a potentially skewed pattern. This is the case when investigating the role of X-linked genetic variants in the occurrence of anti-drug antibodies (ADAs) in patients with autoimmune diseases treated by biotherapies. In this context, we propose a novel test statistic for selecting loci of interest harbored by the X chromosome that are associated with time-to-event data taking into account skewed X-inactivation (XCI-S). The proposed statistic relies on a semi-parametric additive hazard model and is straightforward to implement. Results from the simulation study show that the test provides higher power gains than the score tests from the Cox model (under XCI process or its escape) and the Xu et al.'s XCI-S likelihood ratio test. We applied the test to the data from the real-world observational multicohort study set-up by the IMI-funded ABIRISK consortium for identifying X chromosome susceptibility loci for drug immunogenicity in patients with autoimmune diseases treated by biotherapies. The test allowed us to select two single nucleotide polymorphisms (SNPs) with high linkage disequilibrium (rs5991366 and rs5991394) located in the cytoband Xp22.2 that would have been overlooked by the Cox score tests and the Xu et al.'s XCI-S likelihood ratio test. Both SNPs showed a similar protective effect for drug immunogenicity without any occurrence of ADA positivity for the homozygous females and hemizygous males for the alternative allele. To our knowledge, this is the first study to investigate the association between X chromosome loci and the occurrence of anti-drug antibodies. We think that more X-Chromosome GWAS should be performed and that the test is well-suited for identifying X-Chromosome SNPs, while taking into account all patterns of the skewed X-Chromosome inactivation process.

Pre-Clinical In-Vitro Studies on Parameters Governing Immune Complex Formation

The success of biotherapeutics is often challenged by the undesirable events of immunogenicity in patients, characterized by the formation of anti-drug antibodies (ADA). Under specific conditions, the ADAs recognizing the biotherapeutic can trigger the formation of immune complexes (ICs), followed by cascades of subsequent effects on various cell types. Hereby, the connection between the characteristics of ICs and their downstream impact is still not well understood. Factors governing the formation of ICs and the characteristics of these IC species were assessed systematically in vitro. Classic analytical methodologies such as SEC-MALS and SV-AUC, and the state-of-the-art technology mass photometry were applied for the characterization. The study demonstrates a clear interplay between (1) the absolute concentration of the involved components, (2) their molar ratios, (3) structural features of the biologic, (4) and of its endogenous target. This surrogate study design and the associated analytical tool-box is readily applicable to most biotherapeutics and provides valuable insights into mechanisms of IC formation prior to FIH studies. The applicability is versatile—from the detection of candidates with immunogenicity risks during developability assessment to evaluation of the impact of degraded or post-translationally modified biotherapeutics on the formation of ICs.

Introducing dendritic cell antibody internalization as an immunogenicity risk assessment tool

Aim: Immunogenicity risk assessment assays are powerful tools that assess the relative immunogenicity of potential biotherapeutics. We detail here the development of a novel assay that measures the degree of antibody internalization by antigen-presenting cells as a predictor of immunogenicity. Results & methodology: The assay uses the fluorescence signal from the antibody bound to the outside of the cell as well as inside the cell to determine internalization. To calculate the amount of internalized antibody, the fluorescent signal from the outside was subtracted from the fluorescent signal from the inside, which is referred to as the internalization index. Conclusion: This assay format demonstrated that antibody-based biotherapeutics with higher clinical immunogenicity internalized to a higher degree than therapeutic antibodies with lower clinical immunogenicity.

CTLA4-Ig prevents development of neutralizing antibody formation after continuous treatment with human FVIII in HA rats

INTRODUCTION

Immunogenicity causing development of anti-drug antibodies (ADAs) are major challenges in the treatment of haemophilia, as well as other diseases where proteins are used for treatment. Furthermore, it is a complication for preclinical testing of such therapies in animal models.

AIM

To investigate if the immunosuppressive drug CTLA4 immunoglobulin (CTLA4-Ig) can induce tolerance in haemophilia A (HA) rats receiving recombinant human coagulation factor VIII (rhFVIII) treatment.

METHODS

Two different prophylactic rhFVIII compounds were given intravenously to HA rats for 4 weeks. Both rhFVIII compounds were co-administered with commercially available CTLA4-Ig or human IgG subclass 4 (hIgG4) as control, and blood samples were collected. To functionally test if pharmacological efficacy was retained, rats were subjected to a bleeding experiment under anaesthesia at end of study.

RESULTS

The mean inhibitory level after 4 weeks in rats receiving rhFVIII and hIgG4 was 85.7 BU for octocog alfa and 37.4 BU for rurioctocog alfa pegol. In contrast, co-administration with CTLA4-Ig during rhFVIII therapy prevented the formation of ADAs (both binding and inhibitory) in 14/14 rats receiving octocog alfa and in 7/7 rats receiving rurioctocog alfa pegol. Moreover, we were able to show that the pharmacological efficacy of rhFVIII was preserved.

CONCLUSION

In a rat model with spontaneous bleeding, co-administration of CTLA4-Ig with rhFVIII prevented antibody formation. No FVIII antibodies were detected, demonstrating that CTLA4-Ig co-administration can be applicable as a method to prevent immunogenicity, when evaluating human proteins in preclinical systems permitting continuous pharmacokinetic and pharmacodynamic assessment.

Immunogenicity assessment of bispecific antibody-based immunotherapy in oncology

With increasing numbers of bispecific antibodies (BsAbs) and multispecific products entering the clinic, recent data highlight immunogenicity as an emerging challenge in the development of such novel biologics. This review focuses on the immunogenicity risk assessment (IgRA) of BsAb-based immunotherapies for cancer, highlighting several risk factors that need to be considered. These include the novel scaffolds consisting of bioengineered sequences, the potentially synergistic immunomodulating mechanisms of action (MOAs) from different domains of the BsAb, as well as several other product-related and patient-related factors. In addition, the clinical relevance of anti-drug antibodies (ADAs) against selected BsAbs developed as anticancer agents is reviewed and the advances in our knowledge of tools and strategies for immunogenicity prediction, monitoring, and mitigation are discussed. It is critical to implement a drug-specific IgRA during the early development stage to guide ADA monitoring and risk management strategies. This IgRA may include a combination of several assessment tools to identify drug-specific risks as well as a proactive risk mitigation approach for candidate or format selection during the preclinical stage. The IgRA is an on-going process throughout clinical development. IgRA during the clinical stage may bridge the gap between preclinical immunogenicity prediction and clinical immunogenicity, and retrospectively guide optimization efforts for next-generation BsAbs. This iterative process throughout development may improve the reliability of the IgRA and enable the implementation of effective risk mitigation strategies, laying the foundation for improved clinical success.

Drug levels, anti-drug antibodies and B-cell counts were not predictive of response in rheumatoid arthritis patients on low dose rituximab

OBJECTIVES

The REDO trial showed that ultra-low dose rituximab (500 mg or 200 mg) was similarly effective in the majority of rheumatoid arthritis (RA) patients. This pre-planned secondary analysis investigates 1) associations between rituximab dosage, drug levels, anti-drug antibodies (ADA) and B cell counts and 2) the predictive value of pharmacokinetic and -dynamic parameters, patient, disease and treatment characteristics in relation to response to ultra-low dose rituximab.

METHODS

For 140 RA patients from the REDO trial, differences in drug levels, ADA and B cell counts were examined at baseline, three and six months after dosing. Treatment response was defined as absence of flare and no extra rituximab or > 1 glucocorticoid injection received during follow-up. The association between potential predictors and response was investigated using logistic regression analyses.

RESULTS

Lower doses of rituximab resulted in lower drug levels but did not significantly affect ADA levels and B cell counts. 3 (10.7%), 12 (20.7%) and 7 (13.0%) patients failed to meet response-criteria in respectively the 1000 mg, 500 mg and 200 mg group. Drug levels, ADA and B cell counts as well as patient, disease and treatment characteristics were not predictive for response to ultra-low dose rituximab.

CONCLUSION

Results of this study further support that continued treatment with 500 or 200 mg rituximab is similarly effective as 1000 mg in RA patients doing well on rituximab. These results, combined with absence of clinical dose response relation in the original REDO study, suggest that 200 mg rituximab is not yet the lowest effective rituximab retreatment dose in RA.

Comparison of Timing to Develop Anti-Drug Antibodies to Infliximab and Adalimumab Between Adult and Pediatric Age Groups, Males and Females

OBJECTIVE

To compare the timing of serum anti-drug antibodies in adult and pediatric age groups, males and females, treated for inflammatory bowel disease or arthritis with adalimumab or infliximab by retrospectively combining data collected during a 2-year therapeutic drug monitoring period.

METHODS

Four hundred thirty sera were divided in groups collected at 0, 3, 6, 12, and 24 months (T0, T3, T6, T12, and T24) after initiation of therapy and assayed for drug and relative anti-drug antibodies levels. At each time point, the percentage of sera presenting anti-drug antibodies, as well as the drug concentrations, were calculated and correlated with patient age and sex.

RESULTS

Anti-drug antibodies were present in 31.5% of sera and were significantly higher in the pediatric age group than in the adult age group, through all time points. The percentages of sera showing anti-drug antibodies were significantly different as early as 3 months and were sera from pediatric female group. The percentages of sera showing anti-drug antibodies reached the highest value at 6 months in the pediatric age group and at 12 months in the adult age group.

CONCLUSIONS

Sera from pediatric had an earlier presence of anti-drug antibodies than adults. In particular, pediatric females sera showed the fastest anti-drug antibodies development.

The efficacy of immunomodulators in the prevention and suppression of anti-drug antibodies to anti-tumor necrosis factor therapy in inflammatory bowel disease

The development of biological agents against tumor necrosis factor (TNF) has revolutionized the management of inflammatory bowel disease (IBD), frequently achieving induction and maintenance of remission in both ulcerative colitis and Crohn's disease. However, a loss of response due to the development of anti-drug antibodies (ADA) is seen annually in approximately 20% of IBD patients receiving anti-TNF therapy. Current evidence suggests that the use of immunomodulators (IMM), such as thiopurines (azathioprine and 6-mercaptopurine) or methotrexate, may prevent or suppress ADA formation. In this article, we present a comprehensive review of the available literature regarding the efficacy of IMM in the prevention and suppression of ADA development to anti-TNF therapy in patients with IBD.

Immune Complex Formation Is Associated With Loss of Tolerance and an Antibody Response to Both Drug and Target

AMG 966 is a bi-specific, heteroimmunoglobulin molecule that binds both tumor necrosis factor alpha (TNFα) and TNF-like ligand 1A (TL1A). In a first-in-human clinical study in healthy volunteers, AMG 966 elicited anti-drug antibodies (ADA) in 53 of 54 subjects (98.1%), despite a paucity of T cell epitopes observed in T cell assays. ADA were neutralizing and bound to all domains of AMG 966. Development of ADA correlated with loss of exposure. In vitro studies demonstrated that at certain drug-to-target ratios, AMG 966 forms large immune complexes with TNFα and TL1A, partially restoring the ability of the aglycosylated Fc domain to bind FcγRIa and FcγRIIa, leading to the formation of ADA. In addition to ADA against AMG 966, antibodies to endogenous TNFα were also detected in the sera of subjects dosed with AMG 966. This suggests that the formation of immune complexes between a therapeutic and target can cause loss of tolerance and elicit an antibody response against the target.

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

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

HLA-DQA1*05 Associates with Extensive Ulcerative Colitis at Diagnosis: An Observational Study in Children

The human leukocyte antigen (HLA) allele group HLA-DQA1*05 predisposes to ulcerative colitis (UC) and is associated with the development of antibodies against infliximab in patients with inflammatory bowel disease (IBD). Therefore, we hypothesized that the presence of HLA-DQA1*05 correlates with characteristics of pediatric IBD. Within a multi-center cohort in Poland, the phenotype at diagnosis and worst flare was established and HLA-DQA1*05 status was assessed enabling genotype-phenotype analyses. HLA-DQA1*05 was present in 221 (55.1%) out of 401 children with IBD (UC n = 188, Crohn's disease n = 213). In UC, the presence of HLA-DQA1*05 was moderately associated with a large extent of colonic inflammation at diagnosis (E4 55% more frequent in HLA-DQA1*05-positive patients, p = 0.012). PUCAI at diagnosis (p = 0.078) and the time from UC diagnosis to the first administration of biologic treatment (p = 0.054) did not differ depending on HLA-DQA1*05 status. The number of days of hospitalization for exacerbation was analyzed in 98 patients for whom sufficient follow-up was available and did not differ depending on HLA-DQA1*05 carriership (p = 0.066). HLA-DQA1*05 carriers with CD were less likely to present with both stenosing and penetrating disease (B2B3, p = 0.048) and to have active disease proximal to the ligament of Treitz (L4a) at the worst flare (p = 0.046). Future research focusing on explaining and preventing anti-TNF immunogenicity should take into account that ADA may develop not only as an isolated reaction to anti-TNF exposure but also as a consequence of intrinsic differences in the early course of UC.

How to Prevent and Mitigate Hypersensitivity Reactions to Biologicals Induced by Anti-Drug Antibodies?

Biologicals are widely used therapeutic agents for rheumatologic diseases, cancers, and other chronic inflammatory diseases. They are characterized by complex structures and content of variable amounts of foreign regions, which may lead to anti-drug antibodies (ADA) development. ADA onset may limit the clinical usage of biologicals because they may decrease their safety. In fact they are mainly associated with immediate hypersensitivity reactions (HSRs). Development of ADAs is reduced by concomitant immunosuppressive treatment, while it is increased by longer intervals between drug administrations; thus, regular infusion regimens should be preferred to reduce HSRs. Once ADAs have formed, some procedures can be implemented to reduce the risk of HSRs. ADAs may belong to different isotype; the detection of IgE ADA is advisable to be assessed when high and early ADAs are detected, in order to reduce the risk of severe HRs. In patients who need to reintroduce the biological culprit, as alternative therapies are not available, drug desensitization (DD) may be applied. Desensitization should be conceptually dedicated to patients with an IgE-mediated HSR; however, it can be performed also in patients who had developed non-IgE-mediated HSRs. Although the underlying mechanisms behind successful DD has not been fully clarified, the DD procedure is associated with the inhibition of mast cell degranulation and cytokine production. Additionally, some data are emerging about the inhibition of drug-specific immune responses during DD.

Secondary failure: immune responses to approved protein therapeutics

Recombinant therapeutic proteins are a broad class of biological products used to replace dysfunctional human proteins in individuals with genetic defects (e.g., factor VIII for hemophilia) or, in the case of monoclonal antibodies, bind to disease targets involved in cancers, autoimmune disorders, or other conditions. Unfortunately, immunogenicity (immune response to the drug) remains a key impediment, potentially affecting the safety and efficacy of these therapeutics. Immunogenicity risk is routinely evaluated during the licensure of therapeutic proteins. However, despite eliciting anti-drug immune responses in at least some patients, most protein drugs are nevertheless licensed as they address unmet medical needs. The pre-licensure immunogenicity assessments of therapeutic proteins are the subject of numerous reviews and white papers. However, observation and clinical management of the immunogenicity of approved therapeutic proteins face additional challenges. We survey the immunogenicity of approved therapeutic proteins, discuss the clinical management of immunogenicity, and identify the challenges to establishing clinically relevant immunogenicity assays for use in routine clinical practice.

Anti-drug antibodies to antibody-based therapeutics in multiple sclerosis

Multiple sclerosis is the major demyelinating autoimmune disease of the central nervous system. Relapsing MS can be treated by a number of approved monoclonal antibodies that currently target: CD20, CD25 (withdrawn), CD49d and CD52. These all target potentially pathogenic memory B cell subsets and perhaps functionally inhibit pathogenic T cell function. These consist of chimeric, humanized and fully human antibodies. However, despite humanization it is evident that all of these monoclonal antibodies can induce binding and neutralizing antibodies ranging from < 1% to over 80% within a year of treatment. Importantly, it is evident that monitoring these allow prediction of future treatment-failure in some individuals and treatment cessation and switching therefore potentially limiting disease breakthrough and disability accumulation. In response to the COVID-19 pandemic and the need to avoid hospitals, shortened infusion times and extended dose intervals have been implemented, importantly, subcutaneous delivery of alternative treatments or formulations have been developed to allow for home treatment. Therefore, hospital-based and remote monitoring of ADA could therefore be advantageous to optimize patient responses in the future.

Refractory Pediatric Psoriasis and Atopic Dermatitis: The Importance of Therapeutical Adherence and Biological Management

The rates of refractory pediatric psoriasis and atopic dermatitis (AD) have steadily risen over the last few decades, demanding newer and more effective therapies. This review aims to explore the reasons for resistant disease, as well as its management; this includes the indications for, efficacy of, and safety of current therapies for refractory pediatric dermatologic disease. A PubMed search for key phrases was performed. Poor medication adherence is the most common cause of resistant disease and may be managed with techniques such as simplified treatment regimens, more follow-ups and educational workshops, as well as framing and tailoring. Once problems with adherence are ruled out, escalating treatment to stronger biologic therapy may be indicated. Development of anti-drug antibodies (ADAs) can cause patients’ disease to be refractory in the presence of potent biologics, which may be addressed with regular medication use or concomitant methotrexate. If patients with AD fail to respond to biologic therapy, a biopsy to rule out mycosis fungoides, or patch testing to rule out allergic contact dermatitis, may be indicated. A limitation of this study is the absence of more techniques for the management of poor medication adherence. Managing medication adherence, escalating treatment when appropriate, and addressing possible anti-drug antibodies will help assure control and relief for patients with resistant disease.

Immunogenicity of biologics used in the treatment of inflammatory bowel disease: A review

PURPOSE OF THE REVIEW

Here we critically evaluate the literature on immunotherapy failure in inflammatory bowel disease patients. In particular anti-drug antibody production, and subsequently loss of response as the primary cause of immunotherapy failure in IBD patients. The benefits of shifting from the "standard" empirical dose escalation approach to therapeutic drug monitoring with anti-TNFα therapy is explored.

RECENT FINDINGS

The American Gastroenterology Association and British Society of Gastroenterology both currently recommend the use of reactive therapeutic drug monitoring to guide treatment, following loss of response in inflammatory bowel disease patients with active disease. However, further research is required to prove the efficacy of a proactive therapeutic drug monitoring approach alone in remitted IBD patients.

SUMMARY

A combination of personalised monitoring approach for anti-drug antibodies and therapeutic drug monitoring could provide beneficial treatment outcome for people with inflammatory bowel disease by predicting drug failure prior to clinical symptoms and allowing timely switching to an alternative drug.

Impact of immunogenicity on clinical efficacy and toxicity profile of biologic agents used for treatment of inflammatory arthritis in children compared to adults

The treatment of inflammatory arthritis has been revolutionised by the introduction of biologic treatments. Many biologic agents are currently licensed for use in both paediatric and adult patients with inflammatory arthritis and contribute to improved disease outcomes compared with the pre-biologic era. However, immunogenicity to biologic agents, characterised by an immune reaction leading to the production of anti-drug antibodies (ADAs), can negatively impact the therapeutic efficacy of biologic drugs and induce side effects to treatment. This review explores for the first time the impact of immunogenicity against all licensed biologic treatments currently used in inflammatory arthritis across age, and will examine any significant differences between ADA prevalence, titres and timing of development, as well as ADA impact on therapeutic drug levels, clinical efficacy and side effects between paediatric and adult patients. In addition, we will investigate factors associated with differences in immunogenicity across biologic agents used in inflammatory arthritis, and their potential therapeutic implications.

Immunogenicity of biologics used in the treatment of moderate to severe psoriasis

The number of biologic drugs available for the treatment of psoriasis continue to expand. However, being biological proteins and thus potentially immunogenic, there is evidence that anti-drug-antibodies develop against the various therapeutic proteins currently being utilised. Although chimeric antibodies that contain elements of the parental rodent monoclonal antibodies are immunogenic, anti-drug antibodies occur even if the biologic is a fully human protein and these can impact on clinical efficacy and safety. However, there is a wide variation in the reported level of anti-drug-antibodies for the same and different treatments that is highlighting issues with various assays used in anti-drug antibody detection. Here we review the available data on the occurrence of anti-drug antibodies in people with psoriasis treated with biologic agents.

Anti-cancer Immunotoxins, Challenges, and Approaches

The development of recombinant immunotoxins (RITs) as a novel therapeutic strategy has made a revolution in the treatment of cancer. RITs result from the fusion of antibodies to toxin proteins for targeting and eliminating cancerous cells by inhibiting protein synthesis. Despite indisputable outcomes of RITs regarding inhibition of multiple cancer types, high immunogenicity has been known as the main obstacle in the clinical use of RITs. Various strategies have been proposed to overcome these limitations, including immunosuppressive therapy, humanization of the antibody fragment moiety, generation of immunotoxins originated from endogenous human cytotoxic enzymes, and modification of the toxin moiety to escape the immune system. This paper is devoted to review recent advances in the design of immunotoxins with lower immunogenicity.