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P319 Trough levels of adalimumab better correlate with combined mucosal and transmural healing than clinical remission in Korean patients with Crohn’s disease on adalimumab maintenance therapy

E. H. Oh*1, A-R. Yoon2, S. H. Park3, J. Kim1, N. Ham1, E. M. Song1, S. W. Hwang1,2, S. H. Park1,2, D-H. Yang1, J-S. Byeon1, S-J. Myung1, S-K. Yang1,2, B. D. Ye1,2

1Asan Medical Center, Gastroenterology, Seoul, South Korea, 2Asan Medical Center, Inflammatory Bowel Disease Center, Seoul, South Korea, 3Asan Medical Center, Radiology, Seoul, South Korea

Background

Studies on correlations between trough levels of adalimumab (TLAs) and levels of antibody to adalimumab (ATA levels) with combined mucosal and transmural healing as well as clinical remission in Crohn’s disease (CD) in non-Caucasians are still lacking.

Methods

TLAs and ATA levels were measured using prospectively collected serum samples drawn from CD patients on adalimumab (ADL) maintenance therapy for more than 1 year at Asan Medical Center, South Korea, from August 2017 to July 2018. We analysed correlations between TLA/ATA levels and combined mucosal and transmural healing as well as clinical remission. TLAs/ATA levels according to concomitant immunomodulator use were also evaluated.

Results

This study included 189 serum samples drawn from 149 patients. Ninety-eight patients were males (65.8%). The median age at diagnosis of CD and at starting ADL was 21.0 years (interquartile range [IQR], 18.0–28.0) and 31.0 years (IQR, 23.0–37.5), respectively. Fifty patients (33.6%) have been previously exposed to infliximab. Clinical remission (Crohn’s disease activity index [CDAI] < 150) was observed in 77.8% (147/189 samples) and combined mucosal and transmural healing was observed in 16.2% (18/111 samples). TLAs differed significantly between two groups divided by a cut-off value of ATA as 4 µg/ml-eq (7.051 µg/ml [IQR 5.185–10.191] in ATI-negative samples [n = 182 {96.3%}] vs. 0.001 µg/ml [IQR 0.001–0.677] in ATI-positive samples [n = 39 {6.2%}], p < 0.001). TLAs showed significant differences between groups with or without combined mucosal and transmural healing (9.817 µg/ml [IQR 7.665–12.488] vs. 7.051 µg/ml [IQR 5.185–10.191], p = 0.010) but not between groups with or without clinical remission (7.891 µg/ml [IQR 5.477–10.835] vs. 6.786 µg/ml [IQR 4.080–11.031], p = 0.171). There was no difference in TLAs and ATA levels without/with concomitant immunomodulator use at the time of measuring TLAs/ATA levels, during induction period and continuously from induction period to the time of measuring TLAs/ATA levels (Table 1).

Abstract P320 – P320

TLAs (µg/ml)ATA levels (µg/ml-eq)
Non-useUseNon-useUse
At the time of measuring TLAs/ATA levels8.176 (6.009–10.845)7.291 (5.219–10.926)0.001 (0.001–0.001)0.001 (0.001–0.001)
p = 0.599p = 0.743
During induction period7.891 (5.337–10.947)7.626 (5.347–10.861)0.001 (0.001–0.001)0.001 (0.001–0.001)
p = 0.903p = 0.453
Continuously from induction period to the time of measuring TLAs/ATA levels8.007 (5.526–10.945)7.291 (5.266–10.668)0.001 (0.001–0.001)0.001 (0.001–0.001)
p = 0.833p = 0.172
*Median (interquartile range)

TLAs/ATA levels according to concomitant immunomodulator use.

TLAs above 11.79, 12.00 and 14.76 µg/ml (area under the receiver-operating characteristic curve = 0.695) identified patients on deep healing with specificities of 85%, 90% and 95%, respectively.

Conclusion

TLAs better correlated with combined mucosal and transmural healing than clinical remission in Korean CD patients on ADL maintenance therapy. There was no difference in TLAs/ATA levels according to concomitant immunomodulator use.