Contribution of enhanced engagement of antigen presentation machinery to the clinical immunogenicity of a human interleukin (IL)‐21 receptor‐blocking therapeutic antibody

Reliable risk assessment for biotherapeutics requires accurate evaluation of risk factors associated with immunogenicity. Immunogenicity risk assessment tools were developed and applied to investigate the immunogenicity of a fully human therapeutic monoclonal antibody, ATR‐107 [anti‐interleukin (IL)‐21 receptor] that elicited anti‐drug antibodies (ADA) in 76% of healthy subjects in a Phase 1 study. Because the ATR‐107 target is expressed on dendritic cells (DCs), the immunogenicity risk related to engagement with DC and antigen presentation pathways was studied. Despite the presence of IL‐21R on DCs, ATR‐107 did not bind to the DCs more extensively than the control therapeutic antibody (PF‐1) that had elicited low clinical ADA incidence. However, ATR‐107, but not the control therapeutic antibody, was translocated to the DC late endosomes, co‐localized with intracellular antigen‐D related (HLA‐DR) molecules and presented a dominant T cell epitope overlapping the complementarity determining region 2 (CDR2) of the light chain. ATR‐107 induced increased DC activation exemplified by up‐regulation of DC surface expression of CD86, CD274 (PD‐L1) and CD40, increased expansion of activated DC populations expressing CD86^hi, CD40^hi, CD83^hi, programmed death ligand 1 (PD‐L1)^hi, HLA‐DR^hi or CCR7^hi, as well as elevated secretion of tumour necrosis factor (TNF)‐α by DCs. DCs exposed to ATR‐107 stimulated an autologous T cell proliferative response in human donor cells, in concert with the detection of immunoglobulin (Ig)G‐type anti‐ATR‐107 antibody response in clinical samples. Collectively, the enhanced engagement of antigen presentation machinery by ATR‐107 was suggested. The approaches and findings described in this study may be relevant to identifying lower immunogenicity risk targets and therapeutic molecules.     

Immunogenicity of therapeutic proteins: Influence of aggregation

Abstract

The elicitation of anti-drug antibodies (ADA) against biotherapeutics can have detrimental effects on drug safety, efficacy, and pharmacokinetics. The immunogenicity of biotherapeutics is, therefore, an important issue. There is evidence that protein aggregation can result in enhanced immunogenicity; however, the precise immunological and biochemical mechanisms responsible are poorly defined. In the context of biotherapeutic drug development and safety assessment, understanding the mechanisms underlying aggregate immunogenicity is of considerable interest. This review provides an overview of the phenomenon of protein aggregation, the production of unwanted aggregates during bioprocessing, and how the immune response to aggregated protein differs from that provoked by non-aggregated protein. Of particular interest is the nature of the interaction of aggregates with the immune system and how subsequent ADA responses are induced. Pathways considered here include ‘classical’ activation of the immune system involving antigen presenting cells and, alternatively, the breakdown of B-cell tolerance. Additionally, methods available to screen for aggregation and immunogenicity will be described. With an increased understanding of aggregation-enhanced immune responses, it may be possible to develop improved manufacturing and screening processes to avoid, or at least reduce, the problems associated with ADA.     

Influence of Escherichia coli chaperone DnaK on protein immunogenicity

The production of anti‐drug antibodies can impact significantly upon the safety and efficacy of biotherapeutics. It is known that various factors, including aggregation and the presence of process‐related impurities, can modify and augment the immunogenic potential of proteins. The purpose of the investigations reported here was to characterize in mice the influence of aggregation and host cell protein impurities on the immunogenicity of a humanized single‐chain antibody variable fragment (scFv), and mouse albumin. Host cell protein impurities within an scFv preparation purified from Escherichia coli displayed adjuvant‐like activity for responses to the scFv in BALB/c strain mice. The 70 000 MW E. coli chaperone protein DnaK was identified as a key contaminant of scFv by mass spectrometric analysis. Preparations of scFv lacking detectable DnaK were spiked with recombinant E. coli DnaK to mimic the process‐related impurity. Mice were immunized with monomeric and aggregated preparations, with and without 0·1% DnaK by mass. Aggregation alone enhanced IgM and IgG2a antibody responses, but had no significant effect on total IgG or IgG1 responses. The addition of DnaK further enhanced IgG and IgG2a antibody responses, but only in the presence of aggregated protein. DnaK was shown to be associated with the aggregated scFv by Western blot analysis. Experiments with mouse albumin showed an overall increase in immunogenicity with protein aggregation alone, and the presence of DnaK increased the vigour of the IgG2a antibody response further. Collectively these data reveal that DnaK has the potential to modify and enhance immunogenicity when associated with aggregated protein.     

Immunogenicity of allogeneic mesenchymal stem cells transplanted via different routes in diabetic rats

Due to their hypoimmunogenicity and unique immunosuppressive properties, mesenchymal stem cells (MSCs) are considered one of the most promising adult stem cell types for cell therapy. Although many studies have shown that MSCs exert therapeutic effects on several acute and subacute conditions, their long-term effects are not confirmed in chronic diseases. Immunogenicity is a major limitation for cell replacement therapy, and it is not well understood in vivo. We evaluated the immunogenicity of allogeneic MSCs in vivo by transplanting MSCs into normal and diabetic rats via the tail vein or pancreas and found that MSCs exhibited low immunogenicity in normal recipients and even exerted some immunosuppressive effects in diabetic rats during the initial phase. However, during the later stage in the pancreas group, MSCs expressed insulin and MHC II, eliciting a strong immune response in the pancreas. Simultaneously, the peripheral blood mononuclear cells in the recipients in the pancreas group were activated, and alloantibodies developed in vivo. Conversely, in the tail vein group, MSCs remained immunoprivileged and displayed immunosuppressive effects in vivo. These data indicate that different transplanting routes and microenvironments can lead to divergent immunogenicity of MSCs.     

Transferon™, a peptide mixture with immunomodulatory properties is not immunogenic when administered with various adjuvants

Transferon, a human dialyzable leukocyte extract (hDLE), is a biotherapeutic that comprises a complex mixture of low-molecular-weight peptides (3, incomplete Freund's adjuvant (IFA), or Titermax Gold. The inoculation scheme entailed three routes of administration (intraperitoneal, Day 1; subcutaneous, Day 7; and intramuscular, Day 14) using 200?μg Transferon/inoculation. Serum samples were collected on Day 21. Total IgG levels were quantitated by affinity chromatography, and specific antibodies against components of Transferon were analyzed by dot-blot and ELISA. Ovalbumin (OVA, 44?kDa) and peptides from hydrolyzed collagen (PFHC,?相似文献   

The effect of haptens on protein‐carrier immunogenicity

The immune response against hapten is T‐cell‐dependent, and so requires the uptake, processing and presentation of peptides on MHC class II molecules by antigen‐presenting cells to the specific T cell. Some haptens, following conjugation to the available free amines on the surface of the carrier protein, can reduce its immunogenicity. The purpose of this study was to explore the mechanism by which this occurs. Four proteins were tested as carriers and six molecules were used as haptens. The immune response to the carrier proteins was reduced > 100‐fold by some of the haptens (termed carrier immunogenicity reducing haptens – CIRH), whereas other haptens did not influence the protein immunogenicity (carrier immunogenicity non‐reducing haptens – nCIRH). Conjugation of the protein to a CIRH affected protein degradation by lysosomal cathepsins, leading to the generation of peptides that differ in length and sequence from those derived from the same native protein or that protein modified with nCIRH. Injection of CIRH‐conjugated protein into mice induced an increase in the population of regulatory T cells. The results of this study provide a putative mechanism of action for the reduction of immune response to haptenated proteins.     

Immunogenicity issues in drug development

Immunogenicity is an important factor that manufacturers must consider as they develop new protein therapeutics. It is important to understand the immunogenicity of new proteins both at the preclinical phase and in the clinical phase of development. This paper provides an overview of the issues that manufacturers should consider including some of the potential reasons that some proteins induce an immune response, a discussion regarding current methodology used to understand immunogenicity, and some examples of marketed protein therapeutics with immunogenicity issues. Given the increasing scrutiny from regulatory agencies around the way immunogenicity is assessed by manufacturers, the strategy of detecting and characterizing antibodies that are formed against protein therapeutics is becoming an important topic. Screening assays are typically performed first on all serum samples collected in the course of a trial to detect the presence of antibodies that can bind to the protein therapeutic. There are several platforms in use: radioimmune precipitation assays (RIP), enzyme linked immunosorbent assays (ELISA), electrochemiluminescent assays (ECL), and biosensor-based assays. Each has its advantages and disadvantages, and needs to be evaluated to identify the optimal platform for a specific therapeutic protein. Once antibodies are identified, a confirmatory assay is performed to verify and characterize the antibodies. A biological assay should be used next to test if these antibodies are capable of neutralizing the biological effect of the drug. Any sample that is positive for neutralizing antibodies, indicates that the antibody is probably having an impact on the patient's ability to derive full benefit from the therapeutic protein, and may be critical for patient safety.     

Immunogenicity of protein therapeutics

Protein therapeutics, such as monoclonal antibodies, enzymes and toxins, hold significant promise for improving human health. However, repeated administration of protein therapeutics, whether natural or recombinant, often leads to the induction of undesirable anti-drug antibodies (ADAs), which interfere with or neutralize the effect of the drug. Although an immune response to foreign proteins can be expected and is well understood, the basis for the development of responses to therapeutic autologous proteins is the subject of some debate. Inflammatory components of the drug delivery vehicle, T cell responses, T and B cell epitopes in the protein drug, and the associated B cell response are all targets for interventions aimed at reducing ADA responses. Here, we review some theories put forward to explain the immunogenicity of therapeutic proteins and describe some emerging protein-engineering approaches that might prevent the development of anti-drug antibodies.     

Frequent anti-V-region immune response to mouse B72.3 monoclonal antibody

The immune response of 56 colorectal cancer patients to a single infusion of 1 mg of radiolabeled (¹¹¹In) mouse B72.3-GYK-DTPA immunoconjugate was examined using a double-antigen radiometric assay system. The incidence of antibody response was 48% to polyclonal mouse IgG, 71% to mouse B72.3, and 62% to chimeric B72.3. Twelve patients (23%) had an antibody response to B72.3 V region in the absence of binding to polyclonal mouse IgG. An antiidiotype response was demonstrated in sera from 36% of 25 patients examined and correlated well with chimeric B72.3-GYK-DTPA immunoconjugate binding (r=0.72), moderately well with mouse B72.3 binding (r=0.56), and not at all with polyclonal mouse IgG binding (r=0.28). The peak antibody response occurred most frequently 2 weeks postinfusion, although a delayed peak response to chimeric B72.2 occurred in 29% of patients. This study suggests that mouse B72.3 causes an immune response in the majority of patients and that antibody response to the V region is common. Understanding the physiological significance of these antibody responses will require correlation with the kinetics and tumor localization of repeat infusions of such immunoconjugates.     

Prediction of Immunogenicity of Therapeutic Proteins

Most protein therapeutics have the potential to induce undesirable immune responses in patients. Many patients develop anti-therapeutic antibodies, which can affect the safety and efficacy of the therapeutic protein, particularly if the response is neutralizing. There are a variety of factors that influence the immunogenicity of protein therapeutics and, in particular, the presence of B- and T-cell epitopes is considered to be of importance. In silico tools to identify the location of both B- and T-cell epitopes and to assess the potential for immunogenicity have been developed, and such tools provide an alternative to more complex in vitro or in vivo immunogenicity assays. This article reviews computational epitope prediction methods and also the use of manually curated databases containing experimentally derived epitope data. However, due to the complexities of the molecular interactions involved in epitope recognition by the immune system, the heterogeneity of key proteins in human populations and the adaptive nature of the immune response, in silico methods have not yet achieved a level of accuracy that enables them to be used as stand-alone tools for predicting clinical immunogenicity. Computational methods, particularly with regard to T-cell epitopes, only consider a limited number of events in the process of epitope formation and therefore routinely over-predict the number of epitopes within a molecule. Epitope databases such as the Immune Epitope Database (IEDB) and the proprietary T Cell Epitope Database? (TCED?) have reached a size and level of organization that increases their utility; however, they are not exhaustive. These methods have greatest utility as an adjunct to in vitro assays where they can be used either to reduce the amount and complexity of the in vitro screening, or they can be used as tools to analyze the sequence of the identified epitope in order to locate amino acids critical for its properties.     

Fugetaxis: active movement of leukocytes away from a chemokinetic agent

Chemotaxis or active movement of leukocytes toward a stimulus has been shown to occur in response to chemokinetic agents including members of the recently identified superfamily of proteins called chemokines. Leukocyte chemotaxis is thought to play a central role in a wide range of physiological and pathological processes including the homing of immune cells to lymph nodes and the accumulation of these cells at sites of tissue injury and pathogen or antigen challenge. We have recently identified a novel biological mechanism, which we term fugetaxis (fugere, to flee from; taxis, movement) or chemorepulsion, which describes the active movement of leukocytes away from chemokinetic agents including the chemokine, stromal cell derived factor-1, and the HIV-1 envelope protein, gp120. In this article, we review the evidence that supports the observation that leukocyte fugetaxis occurs in vitro and in vivo and suggestions that this novel mechanism can be exploited to modulate the immune response. We propose that leukocyte fugetaxis plays a critical role in both physiological and pathological processes in which leukocytes are either excluded or actively repelled from specific sites in vivo including thymic emigration, the establishment of immune privileged sites and immune evasion by viruses and cancer. We believe that current data support the thesis that a greater understanding of leukocyte fugetaxis will lead to the development of novel therapeutic approaches for a wide range of human diseases.     

New DiaP277 analogue shifts DCs to tolerogenic,and modulates NF-Kβ1 to suppress autoreactive T lymphocytes in the type 1 diabetic mice

Abstract

Therapeutic efficacy of P277 against type 1 diabetes was extensively investigated and clinically evidenced. Clinical trials Phases I and II concluded promising results, while the data of P277 immunogenicity in Phase III trials represented weak responses that led to abolish medical use. But, a therapeutic performance of P277 cannot be forgotten. So, in order to exploit its therapeutic benefits and improve its immunogenicity, we developed a new analogue VP to optimize therapeutic efficacy and enhancing immunosuppressive modulations. However, new analogue was purified, and then used to immunize diabetic NOD mice to investigate antidiabetic effects through modulation of immunological status. So, DCs immune responses, relative TLRs, MyD88, and NF-Kβ1 mRNA expression on DCs and splenocytes under VP effect were tested. Circulating and intracellular cytokines were also evaluated at treated and non-treated mice. Splenic T lymphocytes proliferation (Th1 and Treg cells) were also determined. Results revealed that VP significantly down regulates DCs maturation through TLR2, TLR4, and MyD88 pathways. It also shifts DCs to a tolerogenic polarization through NF-Kβ1 pathway that mediates Th1 immunosuppression and enhances iTreg expanding in type1diabetes mice. Meanwhile, we noticed that VP significantly enhances iTreg CD25?+?FoxP3+ proliferation. In conclusion, VP showed promising immune potential to modulate immune regulatory responses and shifts DCs to suppress autoreactive Th1 cells which ameliorated immunosuppressive potency in the type1 diabetic mice.     

Overcoming the immunologic response to foreign enzymes in cancer therapy

Foreign enzymes play a part in a variety of cancer treatments and have the potential for a much greater role. In most cases, repeated administration of the enzyme is required for effective therapy, however, this can be restricted by undesirable effects caused by immunogenicity. Repeated or prolonged treatment can lead to an antibody response, and this may neutralize the enzyme and prevent it from remaining in the circulation. Ultimately, this can lead to a diminished therapeutic effect and increase the risk of infusion reactions. More insidiously, there is a danger that antibodies will not only neutralize the foreign enzyme, but will crossreact with a vital component in normal tissue. Such responses can damage normal tissues and give rise to serious clinical syndromes. The aim for enzymes in cancer therapy is to allow repeated treatments without compromising safety or efficacy. This can potentially be achieved by understanding and controlling the immune response and by modifying the enzyme accordingly. A crucial requirement, and one that is particularly challenging for enzymes to achieve, is that the modifications introduced do not interfere with structure, function or stability.     

Myoblasts fail to stimulate T cells but induce tolerance

Recent interest in myoblast transfer and in the use of myoblastsas vehicles in gene therapy has made it important to understandthe potential immunogenicity of allogeneic or neoantlgen-expresslngmyoblasts. Given the problems of producing a pure populationof myoblasts, In this study we used a tumour-derived musclecell line (TE671), with phenotyplc features of myoblasts, whichwe transfected to express HLA-DR1. However, this cell line wasunable to stimulate either established HLA-DR1-specific alloreactlveT cell clones or a primary alloresponse. Nor could it presenthaemagglutlnln peptide HA 306–324 to DR1-restricted, HA306–324-speciflc T cell clones or lines. Indeed, prelncubatlonwith DR1-expressing TE671 and HA 306–324 rendered suchT cells tolerant as Judged by their subsequent inability toproliferate in response to a DR1⁺ B cell line plus peptide HA306–324. These results imply that myoblasts do not providecostlmulatory signals, and are therefore unlikely to stimulateallospeclfic T cells following myoblasts transplantation orto initiate neoantlgen-speclfic immune responses following Invivo transfection.     

Therapeutic protein deimmunization by T‐cell epitope removal: antigen‐specific immune responses in vitro and in vivo

Hirudin III is an effective anti‐coagulant; however, in 40% of treated patients, a high‐titer of anti‐Hirudin III IgG antibodies is observed. Development of antibody responses requires the activation of helper T lymphocyte (HTL), which is dependent on peptide epitopes binding to HLA class II molecules. Based on computational prediction softwares, four new mutants of Hirudin III, T4K, S9G, V21G, and V21K, had been designed with the aim of reducing the binding affinity of these HTL epitopes. The constructed mutants have been purified and assayed for bioactivity. Finally in vitro and in vivo cell‐mediated responses were assessed and humoral immune assays were performed. All modified forms of Hirudin III were active, and showed significantly reduced human T‐cell responses. All mutants indicated lower human IFN‐γ level compared to native Hirudin, and V21K indicated lowest IFN‐γ level. Mice immunized with T4K and V21K showed a significant reduction in total antibody responses and mouse IFN‐γ levels. Mice immunized with V21K after 3rd immunization had lower T‐cell proliferation compared to native Hirudin and other mutants. Based on these results, V21K is proposed as the best alternate Hirudin III candidate with lowest antigenicity. These findings validate our rational design strategy aimed at providing new active analogs of therapeutic proteins with reduced immunogenicity.     

Immunogenicity of recombinant human bocavirus‐1,2 VP2 gene virus‐like particles in mice

Human bocavirus (HBoV), a recently identified pathogen with a worldwide distribution is closely related to paediatric acute respiratory infection and gastroenteritis. The present study was performed to evaluate the immunogenicity of HBoV1 and HBoV2 virus‐like particles (VLPs) as vaccine candidates in mice. Both HBoV1 and HBoV2 VLPs were expressed in the bacmid virus–SF9 cell system. Mice were inoculated three times at 3‐week intervals with HBoV VLPs at one dose intramuscular (i.m.) or intradermal (i.d.) with or without the addition of the alum adjuvant. ELISA was used to detected antibody, and ELISPOT was used to test cellular immune responses. HBoV‐specific IgG antibodies were induced and alum adjuvant improved the antibody titres and avidity, while the inoculation pathway had no influence. T helper type 1/ type 2 immune responses were balanced induced by HBoV1 VLPs but not HBoV2 VLPs. Serum IgG antibody cross‐reactivity rates of the two subtypes were similar, but cross‐reactions of HBoV1 immunization groups were higher. The single i.m. group had more interferon‐γ‐secreting splenocytes. These data indicate that HBoV VP2 VLPs have good immunogenicity with induction of strong humoral and cellular immune responses, and they may be potential candidate vaccines for HBoV infection.     

From ZikV genome to vaccine: in silico approach for the epitope‐based peptide vaccine against Zika virus envelope glycoprotein

Zika virus (ZikV) has emerged as a potential threat to human health worldwide. A member of the Flaviviridae, ZikV is transmitted to humans by mosquitoes. It is related to other pathogenic vector‐borne flaviviruses including dengue, West Nile and Japanese encephalitis viruses, but produces a comparatively mild disease in humans. As a result of its epidemic outbreak and the lack of potential medication, there is a need for improved vaccine/drugs. Computational techniques will provide further information about this virus. Comparative analysis of ZikV genomes should lead to the identification of the core characteristics that define a virus family, as well as its unique properties, while phylogenetic analysis will show the evolutionary relationships and provide clues about the protein's ancestry. Envelope glycoprotein of ZikV was obtained from a protein database and the most immunogenic epitope for T cells and B cells involved in cell‐mediated immunity, whereas B cells are primarily responsible for humoral immunity. We mainly focused on MHC class I potential peptides. YRIMLSVHG, VLIFLSTAV and MMLELDPPF, GLDFSDLYY are the most potent peptides predicted as epitopes for CD4⁺ and CD8⁺ T cells, respectively, whereas MMLELDPPF and GLDFSDLYY had the highest pMHC‐I immunogenicity score and these are further tested for interaction against the HLA molecules, using in silico docking techniques to verify the binding cleft epitope. However, this is an introductory approach to design an epitope‐based peptide vaccine against ZikV; we hope that this model will be helpful in designing and predicting novel vaccine candidates.     

Antibody repertoires in infants and adults: effects of T-independent and T-dependent immunizations

Polysaccharide(PS)-encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis are among the most prevalent bacterial pathogens of humans. Infections caused by these organisms are both common (otitis media, sinusitis) and severe (meningitis, bacteremia). Antibodies directed against the capsular PS of encapsulated bacteria prevent infection by promoting opsonophagocytic killing. Most bacterial PS, however, are type II T-cell-independent (TI-2) antigens that are poorly immunogenic in young children at highest risk of developing disease. Conjugation of bacterial PS to a protein carrier converts the immune response to a T-cell-dependent (TD) form and significantly improves the immunogenicity of PS, especially in infants. H. influenzae type b (Hib) is a major cause of invasive infection in non-immune children. The medical importance of this pathogen and the availability of both TI-2 and TD Hib PS vaccine formulations have made the human anti-Hib-PS immune response an excellent model for the study of the biology of these B cell responses.     

In vitro analysis of metabolic predisposition to drug hypersensitivity reactions

Idiosyncratic hypersensitivity reactions may account for up to 25% of all adverse drug reactions, and pose a constant problem to physicians because of their unpredictable nature, potentially fatal outcome and resemblance to other disease processes. Current understanding of how drug allergy arises is based largely on the hapten hypothesis: since most drugs are not chemically reactive per se, they must be activated metabolically to reactive species which may become immunogenic through interactions with cellular macromolecules. The role of drug metabolism is thus pivotal to the hapten hypothesis both in activation of the parent compound and detoxification of the reactive species. Although conjugation reactions may occasionally produce potential immunogens (for example, the generation of acylglucuronides from non-steroidal anti-inflammatory drugs such as diclofenac), bioactivation is catalysed most frequently by cytochrome P450 (P450) enzymes. The multifactorial nature of hypersensitivity reactions, particularly the role of often unidentified, reactive drug metabolites in antigen generation, has hampered the routine diagnosis of these disorders by classical immunological methods designed to detect circulating antibodies or sensitized T cells. Similarly, species differences in drug metabolism and immune system regulation have largely precluded the establishment of appropriate animal models with which to examine the immunopathological mechanisms of these toxicities. However, the combined use of in vitro toxicity assays incorporating human tissues and in vivo phenotyping (or, ultimately, in vitro genotyping) methods for drug detoxification pathways may provide the metabolic basis for hypersensitivity reactions to several drugs. This brief review highlights recent efforts to unravel the bases for hypersensitivity reactions to these therapeutic agents (which include anticonvulsants and sulphonamides) using drug metabolism and Immunochemical approaches. In particular, examples are provided which illustrate breakthroughs in the identification of the chemical nature of the reactive metabolites which become bound to cellular macromolecules, the enzyme systems responsible for their generation and (possibly) detoxification, and the target proteins implicated in the subsequent immune response.     

Therapeutic drug monitoring with biologic agents in immune mediated inflammatory diseases

ABSTRACT

Introduction: Biologic therapy has revolutionized the treatment of immune mediated inflammatory diseases (IMID), such as inflammatory bowel disease (IBD), rheumatoid and psoriatic arthritis, ankylosing spondylitis and psoriasis. Nevertheless, some patients exhibit primary nonresponse (PNR) or secondary loss of response (SLR) to biologics.

Areas covered: This collaborative review provides data on the role of therapeutic drug monitoring (TDM) in IMID for optimizing biologic therapy including infliximab, adalimumab, certolizumab pegol etanercept and golimumab vedolizumab, secukinumab and ustekinumab.

Expert opinion: Most exposure-response relationship studies show a positive correlation between biologic drug concentrations and favorable therapeutic outcomes in IMID with higher drug concentrations typically associated with more objective outcomes. Clinically, reactive TDM rationalizes the management of PNR and SLR to anti-tumor necrosis factor therapy and is emerging as the new standard of care in IBD as it is also more cost-effective than empiric dose escalation. Preliminary data suggest that proactive TDM with the goal to achieve a threshold drug concentration is associated with better therapeutic outcomes when compared to empiric drug optimization and/or reactive TDM of infliximab and adalimumab in IBD. However, more data from well-designed prospective studies are needed to prove the benefit of TDM-based algorithms in real life clinical practice in IMID.