Optimising Biological Treatment for Patients with Immune-Mediated Inflammatory Diseases Exposure-Response Relation and Therapy-Related Effects

The introduction of biologics has heralded a new era for treatment of immune-mediated inflammatory diseases (IMIDs), including ankylosing spondylitis (AS), psoriasis and inflammatory bowel diseases (IBD). Although these agents show efficacy in many patients, a substantial proportion of patients fails to respond, loses response over time or develops potentially therapy-limiting adverse events. One possible mechanism explaining the failure of biological treatment and increased risk of adverse events involves the generation of anti-drug-antibodies (ADAbs). Many studies have linked low serum drug concentrations of infliximab and adalimumab to a higher risk of ADAb development and/or loss of response to these anti-TNFα agents. As a reaction, reactive measurement of ADAbs and serum drug concentrations (therapeutic drug monitoring, TDM), and appropriate adjustment of drug regimen, has been utilised in practice to optimise clinical outcomes. However, the currently used methods for TDM exhibit large inter-assay variability and often lack sensitivity and specificity. They also rely on blood collection by venipuncture. Not only is this way of sampling impractical and burdensome for patients, it also hampers the evaluation of drug concentrations at time points other than trough. The first two objectives of this PhD project were therefore to develop and apply appropriate assays to explore the potential of TDM for etanercept and golimumab along with a self-sampling method to facilitate their implementation in a clinical environment. With respect to the (therapy-limiting) adverse events, inflammation-induced venous thrombosis (VTE) is a well-known complication of IMIDs; however, its pathogenesis remains to be completely unravelled. Even less is known about the effect of treatment on the risk for VTE, especially for the more recent biological therapies. A third objective was therefore to investigate how infliximab, vedolizumab and methylprednisolone affect the haemostatic profile of IBD patients responding to these therapies. Association between serum concentrations of etanercept, antibodies to etanercept and clinical effectiveness of etanercept therapy In chapter 2, we developed highly sensitive immunoassays for the specific quantification of serum etanercept and anti-etanercept concentrations by generating and extensively characterising a large panel of anti-etanercept mouse monoclonal antibodies. Monoclonal antibodies have the advantage to bind with exquisite specificity to a given epitope on the target antigen. In addition, they are easily reproduced enabling assay standardisation and harmonisation. The MA-ETN63C8/MA-ETN61C1-HRP ELISA was selected as etanercept assay and MA-ETN64A5 could serve as a universal anti-etanercept calibrator to harmonise anti-etanercept assays. Next, we used a prospective observational cohort design (chapter 3) to investigate the relation between etanercept exposure and psoriasis severity. In addition, a novel method for the detection of anti-etanercept antibodies in complex with etanercept was developed and validated. Our study provided a new perspective on the role of age as a factor in treatment strategy decision-making of etanercept-treated patients with psoriasis. We suggested that in patients with an age below 50 years, an increase in etanercept dose is worthwhile considering in case of insufficient control of the psoriasis activity, especially at start of therapy. For patients above 50, higher doses are not recommended unless etanercept treatment has just been initiated. Older patients (>60 years) with a long treatment duration and a good response to therapy, might furthermore be eligible for an intermittent treatment scheme without any risk to develop anti-etanercept antibodies. Association between serum concentrations of golimumab, antibodies to golimumab and clinical effectiveness of golimumab therapy The in-house generation of three mouse monoclonal antibodies to golimumab led to the development of both the TNF/MA-GOM131E3-HRP ELISA and the MA-GOM171D8/MA-GOM159B8-HRP ELISA to quantify golimumab (chapter 4). Both assays showed a good correlation and after optimisation (and conversion into an ELISA kit) of the TNF/MA-GOM131E3-HRP ELISA by apDia, the golimumab concentration results of the two ELISAs could be combined using a recalculation factor. In a retrospective study of patients with UC, we demonstrated that serum golimumab concentration at week 2 and 6, as well as drug exposure (week 0-6), was higher in partial clinical responders than in clinical non-responders. A higher inflammatory burden, approximated by baseline serum C-reactive protein (CRP) and albumin, was associated to a lower golimumab exposure. We could, however, not assign much clinical relevance to the newly-developed drug tolerant ELISA: the detected anti-golimumab antibodies did not lead to undetectable serum golimumab concentrations and the difference in concentration vs. time lines was already established before the second infusion, indicating that the B-cell response might not have been responsible. Therefore, we decided to adequately study the absorption of golimumab and established a simplified method (chapter 5) to allow easy capillary blood sampling (DBS). DBS golimumab concentrations (after application of an overall conversion factor) correlated strongly with serum golimumab concentrations, indicating the method's reliability. Regarding its clinical usefulness, multiple sampling by DBS revealed that golimumab exposure was not captured well by the golimumab trough concentrations during induction. Moreover, through intensive sampling a multiple peak pattern emerged during drug absorption. The observed inter-individual differences in peak concentrations after the first golimumab administration indeed indicated that a part of the observed variability in exposure results from differences in absorption instead of only clearance of the antibody. At the end of the study, DBS sampling was found to be easy and convenient, and most patients preferred to carry out a finger puncture at home than to visit a doctor for a venipuncture. Effect of inflammatory bowel disease-therapy on the haemostatic profiles In a last prospective study (chapter 6), the effect of infliximab, vedolizumab and/or methylprednisolone therapy on the haemostatic profile of IBD patients was investigated, by measuring the concentration of fibronectin and plasminogen activator inhibitor-1 (PAI-1) and performing an in vitro clot-lysis assay before and after induction therapy. Haemostatic parameters were sorted into global markers of haemostasis efficiency (AUC), parameters of coagulation (amplitude, Tmax and fibronectin) and parameters of fibrinolysis (50%CLT and PAI-1 antigen). Our study showed that, before start of therapy, patients had an altered clot-lysis profile compared to healthy controls. Upon effective induction therapy - response was required - the clot-lysis parameters AUC, amplitude and 50%CLT normalised to the level of healthy controls. When comparing the different IBD treatment groups, control of inflammation using infliximab compared to vedolizumab and methylprednisolone, most strongly improved the parameters (Tmax and 50%CLT, respectively) that are associated with a higher risk of VTE. In conclusion, in this PhD project we aimed to improve management of IMID patients. We present novel assays with excellent analytical performance for the quantitative measurements of golimumab and etanercept concentrations along with a self-sampling method to facilitate their implementation. Compelling evidence for etanercept TDM remains limited. By contrast, further investigation into the mechanisms that determine golimumab absorption and exposure might help to optimise this treatment. Finally, a steroid-sparing infliximab but not vedolizumab treatment is advisable in inflammatory bowel disease patients with pro-thrombotic tendencies.status: publishe

The association between etanercept serum concentration and psoriasis severity is highly age-dependent

The association between etanercept serum concentration and psoriasis disease severity is poorly investigated, and currently etanercept serum concentration monitoring that is aiming to optimize the psoriasis treatment lacks evidence. In this prospective study, we investigated the relation between etanercept exposure and disease severity via measuring etanercept concentrations at five consecutive time points in 56 psoriasis patients. Disease severity assessments included the Psoriasis Area and Severity Index (PASI), body surface area (BSA) and Physician Global Assessment (PGA), and etanercept and anti-etanercept antibody concentrations were determined every 3 months for a period of 1 year. The present study demonstrated that the association between etanercept concentration and psoriasis severity is age-dependent: when patients were stratified into three groups, patients in the youngest age group (–50 years) showed a lower PASI at a higher etanercept concentration (β = –0.26), whereas patients in the oldest age group (+59 years) showed the opposite trend (β =0.22). Similar age effects were observed in the relation of etanercept concentration with BSA (P=0.02) and PGA (P=0.02). The influence of age and length of time in therapy on the etanercept concentration–disease severity relation was unaffected by body mass index (BMI) or any other possible confounder. Incidence of anti-etanercept antibodies was low (2%). The age-dependent relation between etanercept serum concentrations is both unexpected and intriguing and needs further investigation.</jats:p