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. 2025 Oct 1;31(10):2886-2894.
doi: 10.1093/ibd/izaf101.

Clinical Utility and Accuracy of Point-of-Care Testing for Anti-TNF Drug Monitoring and Loss of Response

Christoph Teichert  1 , Suzanne I Anjie  1 , Toer W Stevens  1 , Bayda Bahur  2 , Kurtis R Bray  2 , Krisztina B Gecse  1 , Geert R D'Haens  1
Affiliations

Clinical Utility and Accuracy of Point-of-Care Testing for Anti-TNF Drug Monitoring and Loss of Response

Christoph Teichert et al. Inflamm Bowel Dis. .

Abstract

Background and aims: Point-of-care tests (POCT) enable immediate measurement of anti-TNF blood concentrations. This study examined the association between loss of response (LOR) to infliximab (IFX) or adalimumab (ADL) and serum concentrations measured with POCT and enzyme-linked immunosorbent assay (ELISA) in inflammatory bowel disease (IBD) patients.

Methods: Patients with IBD with stored IFX or ADL serum samples were recruited. POCT was conducted, agreement with ELISA was evaluated using Bland-Altman plots. The primary endpoint was LOR defined as change in therapy, IBD-related surgery, new actively draining fistula, and/or endoscopic deterioration. ROC curves and quartile analysis assessed the association between concentrations and LOR.

Results: A total of 176 patients were included (92 IFX/84 ADL, 154 Crohn's disease, and 22 ulcerative colitis). Median follow-up time was 20 months (interquartile range 9-38). LOR occurred in 37/84 (44%) ADL users and 55/92 (60%) IFX users. Median serum concentrations were significantly lower in LOR patients compared with sustained response, measured by both techniques for ADL (POCT: 6.45 vs 13.48 µg/mL, P <.001; ELISA: 4.80 vs 8.80 µg/mL, P <.001) and IFX (POCT: 2.39 vs 6.50 µg/mL, P <.001; ELISA: 1.70 vs 4.40 µg/mL, P <.001). Quartile analysis revealed that higher serum concentrations were associated with maintained response. ROC curve analysis demonstrated good or excellent discrimination for POCT and ELISA in association with LOR (AUC IFX: POCT = 0.82, ELISA = 0.76; AUC ADL: POCT = 0.82, ELISA = 0.81; all P <.0001). An overestimation of serum concentrations with POCT was observed.

Conclusions: Serum ADL and IFX POCT concentrations are comparable to ELISA and associated with LOR, indicating its clinical utility.

Keywords: anti-TNF; loss of response; point-of-care testing; therapeutic drug monitoring.

Plain language summary

This study assessed the association between loss of response (LOR) and infliximab or adalimumab serum concentrations measured by point-of-care testing and ELISA in inflammatory bowel disease patients. POCT correlated well with LOR, supporting its utility in therapeutic drug monitoring.

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Conflict of interest statement

S.A., C.T., and T.S. declare no conflict of interest.

B.B.: is an employee of ProciseDx.

K.B.: is an employee of ProciseDx.

K.G.: has received grants from Pfizer Inc., Celltrion, AbbVie, and Alfasigma; consultancy fees from AbbVie, Alfasigma, Gilead, Immunic Therapeutics, Janssen Pharmaceuticals, Pfizer Inc., Samsung Bioepis and Takeda, and speaker’s honoraria from Celltrion, Ferring, Janssen Pharmaceuticals, Novartis, Pfizer Inc, Samsung Bioepis, Takeda, and Tillotts.

G.D.: has served as advisor and/or speaker for AbbVie, Alimentiv, Amgen, Bristol Myers Squibb, BoehringerIngelheim, Celltrion, Ferring, Engene, Galapagos, Glaxo Smith Kline, Immunic, Index Pharmaceuticals, Johnson and Johnson, Landos, Lilly, Lument, Mitsubishi Pharma, Polpharm, Prometheus biosci-ences, Prometheus laboratories, Procise diagnostics, Protagonist, Sandoz, Setpoint, Takeda, Tillotts, and Versant.

Figures

Figure 1.
Figure 1.
Flow diagram. SOC = Standard of care; TDM = therapeutic drug monitoring; IBD = inflammatory bowel disease; IBD-U = inflammatory bowel disease unspecified; CD = Crohn’s disease; UC = ulcerative colitis; TL = trough level; FU = follow-up; IFX = infliximab; ADL = adalimumab.
Figure 2.
Figure 2.
(A) Median IFX concentrations among patients who maintained or lost response, measured with ELISA (left) and POCT (right). (B) Median ADL concentrations among patients who maintained or lost response, measured with ELISA (left) and POCT (right). Concentrations are depicted as µg/mL.
Figure 3.
Figure 3.
(A) ROC curve for diagnostic performance of IFX serum concentration and LOR measured by ELISA: AUC = 0.76, 95% CI, 0.66-0.86, P < .0001. (B) ROC curve for diagnostic performance of IFX serum concentration and LOR measured by POCT: AUC = 0.82, 95% CI, 0.73-0.91, P < .0001. (C) ROC curve for diagnostic performance of ADL serum concentration and LOR measured by ELISA: AUC = 0.81, 95% CI, 0.710.91, P < .0001. (D) ROC curve for diagnostic performance of ADL serum concentration and LOR measured by POCT: AUC = 0.82, 95% CI, 0.73-0.91, P < .0001.
Figure 4.
Figure 4.
Serum drug concentration quartile analysis for maintained response. (A) Serum infliximab concentrations measured by ELISA. Q1: ≤ 1.3 (N = 3/24), Q2: 1.4-2.8 (N = 5/22), Q3: 2.9-4.6 (N = 13/22), Q4: > 4.7 (N = 16-24), P < .001. (B) Serum infliximab concentrations measured by POCT. Q1: ≤ 3.4 (N = 6/23), Q2: 3.5-6.5 (N = 13/23), Q3: 6.6-11.9 (14/23), Q4: > 11.9 (N = 19/23), P = .004. (C) Serum adalimumab concentrations measured by ELISA. Q1: ≤ 4.8 (N = 3/22), Q2: 4.9-7.3 (N = 11/20), Q3: 7.3-9.7 (N = 15/21), Q4: > 9.7 (N = 18/21), P < .001. (D) Serum adalimumab concentrations measured by POCT. Q1: ≤ 6.6 (N = 2/21), Q2: 6.6-11.5 (N = 12/21), Q3: 11.5-15.0 (N = 16/21), Q4: > 15.0 (N = 17/21), P < .001.
Figure 5.
Figure 5.
Bland–Altman plots. (A) Comparison of ELISA with IFX POCT. (B) Comparison of ELISA with ADL POCT. The y-axis shows the differences between each test result and the x-axis shows the mean of each test result. The blue horizontal line represents the bias (the mean difference between ELISA and POCT), with the absolute number of the bias depicted on the y-axis. Dashed black horizontal lines represent the upper and lower limits of the bias. Blue dots represent each individual participant.
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