Thiopurines and their optimization during infliximab induction and maintenance: A retrospective study in Crohn's disease

Mechanisms and management of loss of response to anti-TNF therapy for patients with Crohn's disease: 3-year data from the prospective, multicentre PANTS cohort study

BACKGROUND

We sought to report the effectiveness of infliximab and adalimumab over the first 3 years of treatment and to define the factors that predict anti-TNF treatment failure and the strategies that prevent or mitigate loss of response.

METHODS

Personalised Anti-TNF therapy in Crohn's disease (PANTS) is a UK-wide, multicentre, prospective observational cohort study reporting the rates of effectiveness of infliximab and adalimumab in anti-TNF-naive patients with active luminal Crohn's disease aged 6 years and older. At the end of the first year, sites were invited to enrol participants still receiving study drug into the 2-year PANTS-extension study. We estimated rates of remission across the whole cohort at the end of years 1, 2, and 3 of the study using a modified survival technique with permutation testing. Multivariable regression and survival analyses were used to identify factors associated with loss of response in patients who had initially responded to anti-TNF therapy and with immunogenicity. Loss of response was defined in patients who initially responded to anti-TNF therapy at the end of induction and who subsequently developed symptomatic activity that warranted an escalation of steroid, immunomodulatory, or anti-TNF therapy, resectional surgery, or exit from study due to treatment failure. This study was registered with ClinicalTrials.gov, NCT03088449, and is now complete.

FINDINGS

Between March 19, 2014, and Sept 21, 2017, 389 (41%) of 955 patients treated with infliximab and 209 (32%) of 655 treated with adalimumab in the PANTS study entered the PANTS-extension study (median age 32·5 years [IQR 22·1-46·8], 307 [51%] of 598 were female, and 291 [49%] were male). The estimated proportion of patients in remission at the end of years 1, 2, and 3 were, for infliximab 40·2% (95% CI 36·7-43·7), 34·4% (29·9-39·0), and 34·7% (29·8-39·5), and for adalimumab 35·9% (95% CI 31·2-40·5), 32·9% (26·8-39·2), and 28·9% (21·9-36·3), respectively. Optimal drug concentrations at week 14 to predict remission at any later timepoints were 6·1-10·0 mg/L for infliximab and 10·1-12·0 mg/L for adalimumab. After excluding patients who had primary non-response, the estimated proportions of patients who had loss of response by years 1, 2, and 3 were, for infliximab 34·4% (95% CI 30·4-38·2), 54·5% (49·4-59·0), and 60·0% (54·1-65·2), and for adalimumab 32·1% (26·7-37·1), 47·2% (40·2-53·4), and 68·4% (50·9-79·7), respectively. In multivariable analysis, loss of response at year 2 and 3 for patients treated with infliximab and adalimumab was predicted by low anti-TNF drug concentrations at week 14 (infliximab: hazard ratio [HR] for each ten-fold increase in drug concentration 0·45 [95% CI 0·30-0·67], adalimumab: 0·39 [0·22-0·70]). For patients treated with infliximab, loss of response was also associated with female sex (vs male sex; HR 1·47 [95% CI 1·11-1·95]), obesity (vs not obese 1·62 [1·08-2·42]), baseline white cell count (1·06 [1·02-1·11) per 1 × 109 increase in cells per L), and thiopurine dose quartile. Among patients treated with adalimumab, carriage of the HLA-DQA1*05 risk variant was associated with loss of response (HR 1·95 [95% CI 1·17-3·25]). By the end of year 3, the estimated proportion of patients who developed anti-drug antibodies associated with undetectable drug concentrations was 44·0% (95% CI 38·1-49·4) among patients treated with infliximab and 20·3% (13·8-26·2) among those treated with adalimumab. The development of anti-drug antibodies associated with undetectable drug concentrations was significantly associated with treatment without concomitant immunomodulator use for both groups (HR for immunomodulator use: infliximab 0·40 [95% CI 0·31-0·52], adalimumab 0·42 [95% CI 0·24-0·75]), and with carriage of HLA-DQA1*05 risk variant for infliximab (HR for carriage of risk variant: infliximab 1·46 [1·13-1·88]) but not for adalimumab (HR 1·60 [0·92-2·77]). Concomitant use of an immunomodulator before or on the day of starting infliximab was associated with increased time without the development of anti-drug antibodies associated with undetectable drug concentrations compared with use of infliximab alone (HR 2·87 [95% CI 2·20-3·74]) or introduction of an immunomodulator after anti-TNF initiation (1·70 [1·11-2·59]). In years 2 and 3, 16 (4%) of 389 patients treated with infliximab and 11 (5%) of 209 treated with adalimumab had adverse events leading to treatment withdrawal. Nine (2%) patients treated with infliximab and two (1%) of those treated with adalimumab had serious infections in years 2 and 3.

INTERPRETATION

Only around a third of patients with active luminal Crohn's disease treated with an anti-TNF drug were in remission at the end of 3 years of treatment. Low drug concentrations at the end of the induction period predict loss of response by year 3 of treatment, suggesting higher drug concentrations during the first year of treatment, particularly during induction, might lead to better long-term outcomes. Anti-drug antibodies associated with undetectable drug concentrations of infliximab, but not adalimumab, can be predicted by carriage of HLA-DQA1*05 and mitigated by concomitant immunomodulator use for both drugs.

FUNDING

Guts UK, Crohn's and Colitis UK, Cure Crohn's Colitis, AbbVie, Merck Sharp and Dohme, Napp Pharmaceuticals, Pfizer, and Celltrion Healthcare.

Key factors associated with 6-thioguanine and 6-methylmercaptopurine nucleotide concentrations in children treated by thiopurine for acute leukaemia and inflammatory bowel disease

AIMS

Azathioprine (AZA) and 6-mercaptopurine are prescribed in acute lymphoblastic leukaemia (ALL) and inflammatory bowel diseases (IBD). Metabolism to active 6-thioguanine (6TGN) and 6-methylmercaptopurine nucleotides (6MMPN) is variable but therapeutic drug monitoring (TDM) remains debatable. This study reports on factors impacting on red blood cell (RBC) metabolites concentrations in children to facilitate TDM interpretation.

METHODS

The first paediatric TDM samples received during year 2021 were analysed, whatever indication and thiopurine drug. Target concentration ranges were 200-500, <6000 pmol/8 × 108 RBC for 6TGN and 6MMPN.

RESULTS

Children (n = 492) had IBD (64.8%), ALL (22.6%) or another autoimmune disease (12.6%): mean ages at TDM were 7.5 in ALL and 13.7 years in IBD (P < .0001). ALL received 6-mercaptopurine (mean dose 1.7 mg/kg/d with methotrexate), IBD received AZA (1.9 mg/kg/d with anti-inflammatory drugs and/or monoclonal antibodies). Median 6TGN and 6MMPN concentrations were 213.7 [interquartile range: 142.5; 309.6] and 1144.6 [419.4; 3574.3] pmol/8 × 108 RBC, 38.8% of patients were in the recommended therapeutic range for both compounds. Aminotransferases and blood tests were abnormal in 57/260 patients: 8.1% patients had high alanine aminotransaminase, 3.4% of patients had abnormal blood count. Factors associated with increased 6TGN were age at TDM and thiopurine methyltransferase genotype in ALL and AZA dose in IBD. The impact of associated treatment in IBD patients was also significant.

CONCLUSION

TDM allowed identification of children who do not reach target levels or remain over treated. Including TDM in follow-up may help physicians to adjust dosage with the aim of reducing adverse effects and improve treatment outcome.

Clusters of Disease Activity and Early Risk Factors of Clinical Course of Pediatric Crohn's Disease

BACKGROUND

This study aimed to define clusters of disease activity and prognostic factors of disease course in a well-characterized cohort of children with Crohn's disease (CD).

METHODS

All patients from the SIGENP IBD (Italian Society of Pediatric Gastroenterology Hepatology and Nutrition Inflammatory Bowel Disease) registry with a 5-year follow-up and 6-monthly evaluation were included. Active disease was defined for each semester as follows: clinical activity (weighted Pediatric Crohn's Disease Activity Index ≥12.5 or Mucosal Inflammation Noninvasive Index ≥8) and active disease on endoscopy (Simple Endoscopic Score for Crohn's Disease >3 or fecal calprotectin >250 µg/g) or imaging. Formula-based clusters were generated based on previously published patterns in adults.

RESULTS

Data from 332 patients were analyzed. A total of 105 (32%) experienced a quiescent disease course; 49 (15%) and 31 (9%) a moderate-to-severe chronically active and chronic intermittent disease, respectively; 104 (31%) and 43 (13%) had active disease in the first 2 years after diagnosis and remission thereafter and vice versa, respectively. Surgery at diagnosis was significantly associated with a quiescent course (odds ratio [OR], 10.05; 95% confidence interval [CI], 3.05-25.22; P=.0005), while growth impairment at the diagnosis and active disease requiring corticosteroids at 6 months were inversely related to the quiescent group (OR, 0.48; 95% CI, 0.27-0.81; P= .007; and OR, 0.35; 95% CI, 0.16-0.71; P= .005, respectively). Perianal involvement at diagnosis and moderate-severe activity at 6 months correlated with disease progression (OR, 3.85; 95% CI, 1.20-12.85; P=.02).

CONCLUSIONS

During the first 5 years of follow-up, one-third of children with CD experience a quiescent course. However, another one-third have a moderate-to-severe disease course. Surgery at the diagnosis is related to a quiescent course, while growth impairment and lack of response to induction therapy correlate with more severe disease activity during follow-up.

Prognostic factors for the efficacy of infliximab in patients with luminal fistulizing Crohn's disease

BACKGROUND

Enteric fistula is one of the penetrating features in Crohn's disease (CD). This study aimed to clarify the prognostic factors for the efficacy of infliximab (IFX) treatment in luminal fistulizing CD patients.

METHODS

We retrospectively included 26 cases diagnosed with luminal fistulizing CD hospitalized in our medical center from 2013 to 2021. The primary outcome of our research was defined as death from all causes and undergoing of any relevant abdominal surgery. Kaplan-Meier survival curves were used to describe overall survival. Univariate and multivariate analyses were used to identify prognostic factors. A predictive model was constructed using Cox proportional hazard model.

RESULTS

The median follow-up time was 17.5 months (range 6-124 months). The 1- and 2-year surgery-free survival rates were 68.1% and 63.2%, respectively. In the univariate analysis, the efficacy of IFX treatment at 6 months after initiation (P < 0.001, HR 0.23, 95% CI 0.01-0.72) and the existence of complex fistula (P = 0.047, HR 4.11, 95% CI 1.01-16.71) was found significantly related to the overall surgery-free survival, while disease activity at baseline (P = 0.099) also showed predictive potential. The multivariate analysis showed that efficacy at 6 months (P = 0.010) was an independent prognostic factor. The C-index of the model for surgery-free survival was 0.923 (P < 0.001), indicating an acceptable predictive effect.

CONCLUSION

Prognostic model including the existence of complex fistula, disease activity at baseline and efficacy of IFX at 6 months may be useful to predict long-term outcome of luminal fistulizing CD patients.

Optimizing Therapies Using Therapeutic Drug Monitoring: Current Strategies and Future Perspectives

Therapeutic drug monitoring (TDM) has emerged as a strategy for treatment optimization in inflammatory bowel diseases to maximize benefit and to reach more stringent, objective end points. Optimal drug concentrations in inflammatory bowel disease vary according to treatment target, disease phenotype, inflammatory burden, and timing of sampling during the treatment cycle. This review provides an update on TDM with biologic and oral small molecules, evaluates the role of reactive vs proactive TDM, and identifies the gaps in current evidence. In the future, adaptations to how we use TDM may contribute further to the goal of personalized treatment in patients with IBD.

Immunomodulators: still having a role?

Immunomodulators, particularly the thiopurines and to a lesser extent methotrexate, were standard of care for inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis, for >40 years. While there has been a renaissance in available therapies with the advent of biologics and small molecules, an impetus remains for the ongoing use of thiopurines and methotrexate. This is particularly true for the maintenance of remission and when used in combination therapy with infliximab to suppress anti-biologic antibodies. This article summarizes the data behind immunomodulator use in Crohn’s disease, focusing on the beneficial role these drugs still have while acknowledging their clinical limitations.