Dried blood samples can support monitoring of infliximab concentrations in patients with inflammatory bowel disease: A clinical validation

Abstract

Aims Therapeutic drug monitoring (TDM) can optimize the efficacy of infliximab (IFX) in patients with inflammatory bowel disease (IBD). Because of the delay between blood samples taken at trough and availability of results, dose adjustments can only be carried out at the next infusion, typically 8 weeks later. Dried blood samples (DBS) performed at home to measure IFX concentrations can reduce the time to adapt dose/dosing interval. Here, we aimed to validate the clinical application of DBS for IFX in IBD patients and to evaluate the feasibility of home sampling. Methods DBS results from 40 IBD patients on IFX treatment were compared to serum sample results at trough, peak, and 3–5 weeks after IFX infusion. Subsequently, patients performed DBS home sampling one week before the next IFX infusion. These were compared to serum concentrations as predicted by Bayesian analysis. Results IFX concentrations from finger prick and venous puncture correlate well. DBS IFX concentrations showed high correlation with serum IFX concentrations (Spearman correlation: ≥0.965), without bias. Passing‐Bablok regression for IFX concentrations in DBS from home sampling also showed no bias (intercept: 1.02 mg L−1 (95% CI −1.77–2.04 mg L−1), slope: 0.82 (95% CI 0.63–1.40)), with reasonable correlation (Spearman correlation: 0.671). Conclusions Timely adjustment of IFX dose/dosing interval can be facilitated by IFX concentration measurement in home‐sampled DBS. DBS is a reliable method to measure IFX and can be used to predict IFX trough concentrations.

The effects of COVID‐19 on IBD prescribing and service provision in a UK tertiary centre

“…This observation has been made elsewhere and if prolonged may have consequences, with the potential for inappropriate dosing, drug toxicity or loss of response 27. The development of point of care assays 28 and methods for remote TDM (for example, using dried blood spots)29 may allow us to overcome these new barriers to TDM.…”

The Evolving Role of Microsampling in Therapeutic Drug Monitoring of Monoclonal Antibodies in Inflammatory Diseases

“…Moreover, considering mAbs are frequently used in chronic diseases requiring treatment over longer period, microsampling methods could add important value to TDM by allowing frequent and convenient concentration monitoring, and timely dose adjustment, which would further maximize the patients’ response. Compared to traditional sampling procedure, microsampling seems better suited especially for the proactive TDM, even though the cost-effectiveness of the latter is still unclear [ 41 , 42 , 43 ].…”

“…Moreover, the stability of the analytes should be examined in all conditions that are expected to be met during the different stages of the microsamples handling [ 9 , 50 , 51 , 52 ]. Validated microsampling methods can promote patient-centric approaches in TDM of mAbs by reducing hospital visits and consequently the possibility of infection exposure, while enabling the clinicians to maintain the adequate patient control and the optimal individualized posology [ 41 , 53 , 54 , 55 , 56 ].…”

“…Nevertheless, mAbs are large proteins and thus partitioning into the blood cells is not expected. Therefore, inclusion of the fixed [ 53 , 54 ] or individual [ 41 ] hematocrit (Hct) values into the models that relate plasma and blood concentrations, may improve accuracy and precision. Bridging studies should also address the differences arising from venous blood sampling using anticoagulant and microsampling where anticoagulant is not included [ 9 ].…”

“…Nevertheless, there are concerns over its optimal dosing regimen and the possible formation of ADA [ 43 , 59 ]. Berends et al [ 41 ], aimed to further optimize infliximab efficacy in patients diagnosed with IBD, by developing a method that could enable the home sampling, shortening the time until the next dose interval adjustment. In this study, a total of 40 IBD patients were included.…”