Therapeutic drug monitoring in inflammatory bowel diseases. Position statement of the Spanish Working Group on Crohn's Disease and Ulcerative Colitis

The treatment of inflammatory bowel disease has undergone a significant transformation following the introduction of biologic drugs. Thanks to these drugs, treatment goals have evolved from clinical response and remission to more ambitious objectives, such as endoscopic or radiologic remission. However, even though biologics are highly effective, a significant percentage of patients will not achieve an initial response or may lose it over time. We know that there is a direct relationship between the trough concentrations of the biologic and its therapeutic efficacy, with more demanding therapeutic goals requiring higher drug levels, and inadequate exposure being common. Therapeutic drug monitoring of biologic medications, along with pharmacokinetic models, provides us with the possibility of offering a personalized approach to treatment for patients with IBD. Over the past few years, relevant information has accumulated regarding its utility during or after induction, as well as in the maintenance of biologic treatment, in reactive or proactive strategies, and prior to withdrawal or treatment de-escalation. The aim of this document is to establish recommendations regarding the utility of therapeutic drug monitoring of biologics in patients with inflammatory bowel disease, in different clinical practice scenarios, and to identify areas where its utility is evident, promising, or controversial.

Polymorphisms indicating risk of inflammatory bowel disease or antigenicity to anti-TNF drugs as biomarkers of response in children

Few genetic polymorphisms predict early response to anti-TNF drugs in inflammatory bowel disease (IBD), and even fewer have been identified in the pediatric population. However, it would be of considerable clinical interest to identify and validate genetic biomarkers of long-term response. Therefore, the aim of the study was to analyze the usefulness of biomarkers of response to anti-TNFs in pediatric IBD (pIBD) as long-term biomarkers and to find differences by type of IBD and type of anti-TNF drug. The study population comprised 340 children diagnosed with IBD who were treated with infliximab or adalimumab. Genotyping of 9 selected SNPs for their association with early response and/or immunogenicity to anti-TNFs was performed using real-time PCR. Variants C rs10508884 (CXCL12), A rs2241880 (ATG16L1), and T rs6100556 (PHACTR3) (p value 0.049; p value 0.03; p value 0.031) were associated with worse long-term response to anti-TNFs in pIBD. DNA variants specific to disease type and anti-TNF type were identified in the pediatric population. Genotyping of these genetic variants before initiation of anti-TNFs would enable, if validated in a prospective cohort, the identification of pediatric patients who are long-term responders to this therapy.

Relationship between vedolizumab serum concentrations in the induction phase and early and sustained response in the first year of treatment in patients with ulcerative colitis

OBJECTIVE

Evidence on the usefulness of proactive monitoring of vedolizumab serum concentrations during the induction phase of treatment is limited. The objective of our study was to evaluate the effectiveness of measuring such concentrations during this phase in predicting response to  treatment in patients with ulcerative colitis with a view to determining whether  patients would benefit from early monitoring of  edolizumab serum concentrations.

METHOD

This was a prospective descriptive study carried out at three public  general hospitals. It included adult patients with ulcerative colitis who were  initiated on vedolizumab at the participating hospitals from June 2019 to June  2020. Vedolizumab serum concentrations were determined  at weeks 6 and 14.  Response to treatment was biologically, clinically, and endoscopically  evaluated at weeks 6, 14, and 52. An analysis was made of the relationship  between vedolizumab serum concentrations at week 6 and early response to  treatment, and of the relationship between the vedolizumab serum  concentrations at weeks 6 and 14 and persistent response at one year.

RESULTS

A total of 45 patients were included of whom 22 (49%) were considered non-responsive after one year and required intensification of treatment. The median (interquartile range) vedolizumab serum  oncentrations obtained at 6 weeks was higher in patients who obtained an  early response and in those who maintained the response at one year than  in  those who did not respond to vedolizumab [27.4 (19.0-40.8) μg/mL vs 15.6  (13.4-28.5) μg/mL; p = 0.018] and [29.9 (19.2-43.2) μg/mL vs 18.2 (15.4- 26.9) μg/mL; p = 0.022] respectively. Vedolizumab serum concentrations ≥  17.3 μg/mL at week 6 were predictive of a good early response, and  edolizumab serum concentrations ≥ 26.1 μg/mL at week 6 predicted a  sustained response at one year. No relationship was found between  edolizumab serum concentrations at week 14 and a sustained response.

CONCLUSIONS

We observed a relationship between vedolizumab serum concentrations determined at week 6, and early and maintained  esponse to vedolizumab therapy in patients with ulcerative colitis, which  supports early drug monitoring during the induction phase to individualize  treatment and increase effectiveness.

Long-term effectiveness and pharmacokinetics of the infliximab biosimilar CT-P13 after switching from the originator during the treatment of inflammatory bowel disease

OBJECTIVE

Switching patients from the originator infliximab to a biosimilar is a measure to expand access to treatments and counteract its negative impact on healthcare budgets. However, industry-independent long-term studies on the effect of switching in real life to support the lack of switch-related problems in inflammatory bowel disease (IBD) patients are sparse, as are studies addressing infliximab pharmacokinetic behaviour. The objectives were to investigate the effectiveness and the pharmacokinetics of CT-P13 after switching from originator infliximab in a real-world population of IBD patients with a follow-up of 2 years.

METHOD

Prospective, single-centre, observational 2 year study conducted in IBD adult patients with stable disease treated with the originator infliximab who were switched to CT-P13. Four time points were defined for follow-up: prior to the switch, 4-8 weeks after the switch, 8 months later, and 2 years later. Outcome measures were the proportion of patients with clinical, endoscopic and biochemical remission, and changes in biochemical inflammation markers (albumin, C-reactive protein, faecal calprotectin) and infliximab clearance.

RESULTS

42 IBD patients were switched, of which 36 (85.7%) remained on CT-P13 throughout the 2 year study period. Only two patients discontinued CT-P13 due to loss of response. The proportion of patients who displayed clinical, endoscopic and biochemical remission were unchanged during the follow-up (p<0.05) and no statistically significant changes were observed in the biochemical markers of disease activity. The median (IQR) clearance estimated for the infliximab originator before the change was 0.364 (0.321-0.415) L/day, and for the CT-P13 biosimilar it was 0.361 (0.323-0.415) L/day 4-8 weeks after the change, and 0.370 (0.334-0.419) L/day 2 years after (p=0.395).

CONCLUSION

Switching from originator infliximab to biosimilar CT-P13 did not affect the long-term clinical outcomes or the pharmacokinetic behaviour. This information provides the clinician more evidence for the success of switching and supports non-medical switching in adult IBD patients.

Biomarkers of disease activity and other factors as predictors of adalimumab pharmacokinetics in inflammatory bowel disease

Inflammatory bowel disease (IBD) is commonly treated with adalimumab. The main objective of the study was to develop a population pharmacokinetic model of adalimumab in IBD patients evaluating the potential biomarkers of disease activity and other factors and its implications in adalimumab dosing. A prospective observational study was performed in adult patients diagnosed with Crohn's disease and ulcerative colitis treated with adalimumab and following a proactive therapeutic drug monitoring of serum concentrations. Adalimumab serum concentrations (ASC) were quantified mainly prior the administration using an enzyme-linked immunosorbent assay (ELISA). A population pharmacokinetic model was developed based on 303 ASC data of 104 IBD patients using non-linear mixed effect modelling approach. Sixty-five ASC from 20 additional patients were randomly selected as an external validation group. A one-compartment model with first order absorption and elimination best describe the ASC time course. Body mass index (BMI), faecal calprotectin (FCP), unexplained decline in ASC and the specific administration pen device exhibited significant influence on apparent clearance (p-value < 0.001). FCP was the inflammatory activity biomarker showing the most relevant impact on adalimumab exposure, higher than C-reactive protein and albumin, and may be useful for adalimumab dosing adjustment. The population-based pharmacokinetic model developed adequately characterized adalimumab exposure in IBD patients. The unexplained decline in ASC, FCP, BMI and the specific administration pen device were identified as meaningful variables significantly influencing adalimumab pharmacokinetics.

A 3-year prospective study of a multidisciplinary early proactive therapeutic drug monitoring programme of infliximab treatments in inflammatory bowel disease

AIMS

Therapeutic drug monitoring (TDM) of trough serum infliximab concentrations has been mainly used in case of loss of response in patients with inflammatory bowel disease (IBD). The aim of this study was to evaluate the effectiveness and safety of a multidisciplinary early proactive TDM (mep-TDM) programme for dose adjustment.

METHODS

A 3-year prospective study was conducted based on a sample of 81 patients who started treatment and were subsequently subjected to mep-TDM with the first control at week 14. Data of a historical control group of 72 patients treated with infliximab and managed with empirical dosing were included. Effectiveness variables were treatment failure, IBD-related surgery and IBD-related hospitalization. Safety variables were serious infusion reactions (SIRs) and adverse reactions. Cox regression was used for survival analysis.

RESULTS

In the mep-TDM study group, compared to the control group, there was a significant reduction in the risk of treatment failure (hazard ratio [HR]: 0.51; 95% confidence interval [CI]: 0.27-0.92; P = .037), IBD-related surgery (HR: 0.14; 95% CI: 0.03-0.65; P = .012) and hospitalization (HR: 0.38; 95% CI: 0.17-0.87; P = .022). SIRs were lower in the mep-TDM group (2.5% vs 10.4%; P < .050); the incidence of adverse reactions was similar (3.7% vs 3.9%; p > .999).

CONCLUSION

This study found that compared to empirical dosing, mep-TDM is associated with improved efficacy and safety of infliximab therapy, reduced IBD-related hospitalization and surgery and incidence of SIRs, and increasing long-term durability of treatment effects.

Study of fall risk-increasing drugs in elderly patients before and after a bone fracture

BACKGROUND

Accidental falls have a significant economic and human impact. The use of certain drugs is one of the modifiable risk factors associated with these events.

OBJECTIVE

The aim of this study was to determine the prevalence of use and to explore changes in treatment with fall-related drugs in patients over 65 years of age admitted as a result of a fall-related fracture.

METHODS

Observational and prospective study performed in a tertiary level hospital. A list of fall risk-increasing drugs (FRIDs) was drawn up. The main study variables were number and type of FRIDs prescribed at admission and 1 month after the fracture and number, type, treating physician and place where changes in FRIDs were implemented.

RESULTS

In total, 252 patients were included. At admission, 91.3% were receiving at least one FRID, mean daily use was 3.1 FRIDs and the most frequently prescribed FRIDs were diuretics (18%), renin-angiotensin system-acting agents (15.8%) and antidepressants (15%). One month later, mean daily use was 3.4 FRIDs (p=0.099) and a significant increase was detected in the use of hypnotics (p=0.003) and antidepressants (p=0.042). A total of 327 changes in treatment were recorded (1.3 changes/patient). Of the changes, 52.6% were new prescriptions, 72.2% occurred at discharge and 56.6% were ordered by a geriatrician.

CONCLUSIONS

The use of FRIDs among patients with a fall-related fracture is very high. This use rises 1 month after the fracture, significantly in the case of hypnotics and antidepressants.