Subtherapeutic concentrations of infliximab and adalimumab are associated with increased disease activity in Crohn's disease

Application of a Precision-Dosing Model to a Real-World Cohort of Patients on Infliximab Maintenance Therapy: Drug Usage and Cost Analysis

Precision-dosing models forecast infliximab doses to achieve targeted trough concentrations in patients with inflammatory bowel disease (IBD). These models have shown to reduce nonresponse and improve patient outcomes. We compared infliximab doses determined by iDOSE precision dosing with standard dosing, and the associated drug costs, in patients with IBD. In this retrospective study, patients with IBD treated with infliximab every 8 weeks at 5 mg/kg were included. An infliximab dose was named dose X if 3 previous infliximab doses, laboratory values including trough infliximab concentrations, and the patient's weight were recorded. The actual dose X was compared to an iDOSE-predicted dose X. Net drug use and costs were evaluated. A total of 174 patients-56% men; median age, 36 (interquartile range, 29-47) years; 135 with Crohn disease; and 31 with ulcerative colitis-were included, with 417 dose X recordings. Median prior infliximab therapy was 2 (0-4) years. Comparing actual dose X with predicted dose X, 52% and 32% of doses were subtherapeutic when aiming for trough concentrations of 5-10 and 3-7 μg/mL, respectively. Treatment costs increased by 102% and 29% for the 2 trough ranges, respectively. On multivariate regression analysis, subtherapeutic infliximab concentrations were associated with ulcerative colitis compared with Crohn disease (odds ratio, 9.81; 95% confidence interval, 1.28-75.40; P = .028) and predose X infliximab trough concentration [odds ratio, 0.07; 95% confidence interval, 0.03-0.15; P < .001]. Over half of maintenance infliximab drug doses were too low to achieve infliximab blood concentrations of 5 μg/mL or greater. While applying precision dosing may improve patient outcomes, drug costs could be considerably greater.

Clinical and Immunological Factors Associated with Recommended Trough Levels of Adalimumab and Infliximab in Patients with Crohn's Disease

Introduction: Up to 40% of patients with Crohn's disease do not respond to treatment with anti-TNF or lose response after the initial benefit. Low drug concentrations have been proposed as the main predictor of treatment failure. Our aim was to study the immunological profile and clinical evolution of patients with Crohn's disease according to the anti-TNF dose and serum trough levels. Methods: Crohn's disease patients in remission treated with infliximab or adalimumab at stable doses for at least for 3 months were included. Serum levels of anti-TNF, TNF-α, interferon-γ, and interleukin IL-12, IL-10, and IL-26 were determined in blood samples taken just before drug administration. Patients were classified according to anti-TNF levels below, within, or above the target level range and the use of intensified doses. Clinical evolution at 6 months was analyzed. Results: A total of 62 patients treated with infliximab (8 on intensified schedule) and 49 treated with adalimumab (7 on intensified schedule) were included. All infliximab-treated patients showed levels within the recommended range, but half of adalimumab-treated patients were below the recommended range. A significant negative relationship between body weight and adalimumab levels was observed, especially in patients treated with intensified doses. Patients with infliximab levels over 8 µg/ml presented higher median IL-10 than patients with in-range levels (84.0 pg/ml, interquartile range [IQR] 77.0-84.8 vs. 26.2 pg/mL, IQR 22.6-38.0; p < 0.001), along with lower values of interferon-γ (312.9 pg/ml, IQR 282.7-350.4 vs. 405.6 pg/ml, IQR 352.2-526.6; p = 0.005). Patients receiving intensified versus non-intensified doses of infliximab showed significantly higher IL-26 levels (91.8 pg/ml, IQR 75.6-109.5 vs. 20.5 pg/ml, IQR 16.2-32.2; p = 0.012), irrespective of serum drug levels. Patients with in-range levels of adalimumab showed higher values of IL-10 than patients with below-range levels (43.3 pg/ml, IQR 35.3-54.0 vs. 26.3 pg/ml, IQR 21.6-33.2; p = 0.001). Patients treated with intensified vs regular doses of adalimumab had increased levels of IL-12 (612.3 pg/ml, IQR 570.2-1353.7 vs. 516.4 pg/mL, IQR 474.5-591.2; p = 0.023). Four patients with low adalimumab levels (19%) and four treated with intensified doses were admitted to a hospital during a follow-up compared to none of the patients with levels within the range. Conclusion: Patients with Crohn's disease treated with infliximab and adalimumab exhibit differences in serum levels of cytokines depending on the drug, dose intensification, and steady state trough serum levels.

The effects of targeted immune-regulatory strategies on tumor-specific T-cell responses in vitro

BACKGROUND

Immune-related adverse events (IrAEs) are auto-immune reactions associated with immune checkpoint inhibitor-based therapy (ICI). Steroids are currently the first-line option for irAE management; however, recent studies have raised concerns regarding their potential impairment of tumor-specific immune responses. In this study, we investigated the in vitro effects of commonly used irAE treatment drugs on the anti-tumor activity of tumor-infiltrating lymphocytes (TILs).

METHODS

Impairment of anti-tumor immune responses by four drugs (antibodies: vedolizumab and tocilizumab; small molecules: mycophenolate mofetil and tacrolimus) reported to be effective in treating irAEs was tested at clinically relevant doses in vitro and compared to a standard moderate dose of corticosteroids (small molecules) or infliximab (antibodies). TIL responses against autologous tumor cell lines, in the presence or absence of irAE drugs, were determined by flow cytometry (short-term tumor-specific T-cell activation) or xCELLigence (T-cell-mediated tumor killing).

RESULTS

None of the tested antibodies influenced T-cell activation or T-cell-mediated tumor killing. Low-dose mycophenolate and tacrolimus did not influence T-cell activation, whereas higher doses of tacrolimus (> 1 ng/ml) impaired T-cell activation comparably to dexamethasone. All tested small molecules impaired T-cell-mediated tumor killing, with high-dose tacrolimus reducing killing at levels comparable to dexamethasone-mediated inhibition. In addition, mycophenolate and tacrolimus alone also demonstrated anti-proliferative effects on tumor cells.

CONCLUSIONS

These data support clinical testing of targeted immune-regulatory strategies in the initial phase of irAE management, as a potential replacement for corticosteroids.

The First WHO International Standard for Adalimumab: Dual Role in Bioactivity and Therapeutic Drug Monitoring

The expanded availability of adalimumab products continues to widen patient access and reduce costs with substantial benefit to healthcare systems. However, the long-term success of these medicines is highly dependent on maintaining consistency in quality, safety and efficacy while minimizing any risk of divergence during life-cycle management. In recognition of this need and demand from global manufacturers, the World Health Organization (WHO) Expert Committee on Biological standardization established the WHO 1^st International standard (IS) for Adalimumab (coded 17/236) in October 2019 with a defined unitage ascribed to each of the individual bioactivities evaluated in the study namely, TNF-α binding, TNF-α neutralization, complement dependent cytotoxicity and antibody-dependent cellular cytotoxicity. For development of the IS, two candidate standards were manufactured as per WHO recommendations. Analysis of extensive datasets generated by testing of a common set of samples including the candidate standards by multiple stakeholders including regulatory agencies using their own qualified assays in a large international collaborative study showed comparable biological activity for the tested candidates for the different activities. Use of a common standard significantly decreased the variability of bioassays and improved agreement in potency estimates. Data from this study clearly supports the utility of the IS as an important tool for assuring analytical assay performance, for bioassay calibration and validation, for identifying and controlling changes in bioactivity during life-cycle management and for global harmonization of adalimumab products. In addition, in a separate multi-center study which included involvement of hospital and clinical diagnostic laboratories, the suitability of the adalimumab IS for therapeutic drug monitoring assays was examined by analysis of data from testing of a common blind coded panel of adalimumab spiked serum samples representative of the clinical scenario along with the IS and in-house standards in diverse immunoassays/platforms. Both commercially available and in-house assays that are routinely used for assessing adalimumab trough levels were included. Excellent agreement in estimates for adalimumab content in the spiked samples was observed regardless of the standard or the method with inter-laboratory variability also similar regardless of the standard employed. This data, for the first time, provides support for the extended applicability of the IS in assays in use for therapeutic drug monitoring based on the mass content of the IS. The adalimumab IS, in fulfilling clinical demand, can help toward standardizing and harmonizing clinical monitoring assays for informed clinical decisions and/or personalized treatment strategies for better patient outcomes. Collectively, a significant role for the adalimumab IS in assuring the quality, safety and efficacy of adalimumab products globally is envisaged.

Correlation of serum levels of anti-tumor necrosis factor agents with perianal fistula healing in Crohn's disease: a narrative review

With the overspread use of measurement of serum levels of anti-tumor necrosis factor (TNF) agents (therapeutic drug monitoring, TDM), new therapeutic strategies have been used in the management of Crohn’s disease (CD). Different targets are correlated with increased levels of circulating drugs. Recent evidence demonstrated that higher serum levels of anti-TNF agents may be associated to better outcomes in perianal fistulizing CD (PFCD). Overall, patients with healed fistulas had higher serum levels of infliximab and adalimumab as compared to those with active drainage. This was demonstrated in some cohort studies, in induction and maintenance, in adults and children with PFCD. In this narrative review, authors summarize current evidence on the use of serum level measurement of anti-TNF agents and its correlation with perianal fistula healing in CD patients. Data on the use of TDM in PFCD is discussed in detail. The retrospective design of the studies and the lack of objective parameters to measure fistula healing are the main limitations of published data. Prospective studies, with central reading of objective radiological parameters, such as pelvic magnetic resonance imaging scores, can improve the level of evidence on the possible advantages of TDM in perianal fistula in CD and are warranted.

Clinical efficacy of infliximab level and anti-infliximab antibody measurement in patients with inflammatory bowel disease: An audit

BACKGROUND AND AIMS

Infliximab (IFX) monitoring has been proposed for effective therapeutic management of inflammatory bowel disease (IBD). There is no data on infliximab levels and its antibody measurement in Indian patients. We assessed the clinical efficacy of IFX level and antibodies to infliximab (ATI) monitoring in IBD patients.

METHODS

Infliximab trough level and antibody testing was done in 50 and 30 IBD patients, respectively using commercially available enzyme-linked immunosorbent assay (ELISA) kits. The levels were correlated with the disease status, albumin, and C-reactive protein (CRP) levels. The clinical efficacy of level-based change in patient management was evaluated.

RESULTS

Of 50 patients, IFX levels were therapeutic in 8, sub-therapeutic in 40, and supra-therapeutic in 2. High ATI titer was present in 8/30 patients. The IFX level did not correlate with the dose of 5 or 10 mg/kg. Based on IFX level and ATI estimation, management was changed in 35 patients: increase in dose in 7, decrease in dosing interval in 17, increase in interval in 2, surgery in 2, change in biologic in 5, and cessation of IFX in 2 patients. Therapy modification based on IFX level improved the clinical response in 25 patients, of whom 5 are in remission at a median duration of 2 years.

CONCLUSION

Most (80%) of the IBD patients had subtherapeutic IFX levels while high ATI titers were found in 27% of the patients. There was no correlation between infliximab dose and drug levels. Therapy modification based on drug level benefitted the majority. Our results suggest that measurement of IFX level assists in attaining therapeutic levels and improves clinical response.

Optimization of infliximab therapy in inflammatory bowel disease using a dashboard approach-an Indian experience

PURPOSE

Infliximab (IFX) therapy in inflammatory bowel disease (IBD) is associated with loss of response in half the patients, due to complex pharmacokinetic and immunological factors. Dashboard's Bayesian algorithms use information from model and individual multivariate determinants of IFX concentration and can predict dose and dosing interval.

AIM

To compare measured IFX concentrations in our laboratory with values predicted by iDose dashboard system and report its efficacy in managing patients not responding to conventional dosing schedule.

METHOD

Clinical history, demographic details, and laboratory findings such as albumin and C-reactive protein (CRP) data of IBD patients (n = 30; median age 23 years (IQR: 14.25 - 33.5)) referred for IFX drug monitoring in our laboratory from November 2017 to November 2019 were entered in iDose software. The IFX concentration predicted by iDose based on this information was compared with that measured in our laboratory. In addition, a prospective dashboard-guided dosing was prescribed in 11 of these 30 patients not responding to conventional dosing and was followed to assess their clinical outcome.

RESULT

IFX monitoring in our 30 patients had shown therapeutic concentration in 12, supratherapeutic in 2 and subtherapeutic concentration in 16 patients. The iDose predicted concentration showed concordance in 21 of these 30 patients. Of 11 patients managed with iDose-assisted prospective dosing, 8 achieved clinical remission, 2 showed partial response, and one developed antibodies.

CONCLUSION

Retrospective data analysis showed concordance between laboratory measured and iDose-predicted IFX level in 70% of patients. iDose-assisted management achieved clinical remission and cost reduction.

Harmonization and standardization of immunogenicity assessment of biotherapeutic products

Understanding of the determinants of immunogenicity, the testing paradigm, the impact of antibody attributes on clinical outcomes and regulatory guidance is leading to harmonized practices for immunogenicity assessment of biotherapeutics. However, generation of robust immunogenicity data for inclusion in product labels to support clinical practice continues to be a challenge. Assays, protocols and antibody positive controls/standards need to be developed in sufficient time to allow assessment of clinical immunogenicity using validated methods and optimized protocols. Standardization and harmonization play a significant role in achieving acceptable results. Harmonization in the postapproval setting is crucial for a valid interpretation of the product's immunogenicity and its clinical effects. Efforts are ongoing to standardize assays where possible for antibody measurement and for measuring product/drug levels by producing reference standards. Provision of such standards will help toward personalized treatment strategies with better patient outcomes.

Determination of lower cut-off levels of adalimumab associated with biochemical remission in Crohn's disease

Background and Aim

Adalimumab is administered and dosed using a standardized treatment regimen. Although therapeutic drug monitoring (TDM) may help optimize treatment efficacy, the lower cut‐off concentration of adalimumab needed to retain disease remission has not been established. This cross‐sectional study of patients with Crohn's disease on stable medication aimed to determine a lower therapeutic drug concentration threshold of adalimumab associated with biochemical disease remission.

Methods

C‐reactive protein (CRP) and fecal calprotectin were used as established markers and albumin as an explorative marker of disease activity. Time since introduction, treatment interval, drug dosage, serum drug concentration and antidrug antibodies, disease duration, age, and sex were recorded.

Results

The study included 101 patients who were divided into “active disease” and “remission” groups for inflammatory markers based on cut‐off levels of 5 mg/L for CRP and 50 mg/kg for fecal calprotectin. Cut‐off levels for albumin of 36.5 and 41.5 g/L were also added as further indicatives of remission. Receiver operating characteristic analysis found optimal thresholds for adalimumab associated with remission at 6.8–7.0 mg/L for the combination of CRP and fecal calprotectin and when combining CRP, fecal calprotectin, and albumin.

Conclusions

In patients with Crohn's disease, serum adalimumab of at least 6.8 mg/L was associated with biochemical disease remission based on CRP and fecal calprotectin, supporting the use of TDM to ensure disease control. Albumin should be further tested in this setting.

Actual Anti-TNF Trough Levels Relate to Serum IL-10 in Drug-Responding Patients With Crohn's Disease

BACKGROUND

Patients with Crohn's disease (CD) responding to anti-tumor necrosis factor (anti-TNF) show great variability in serum drug levels, even within the therapeutic range. We aimed at exploring the role of inflammatory, genetic, and bacterial variables in relation to anti-TNF through levels in CD patients.

METHODS

Consecutive CD patients receiving stable doses of infliximab or adalimumab were included. Clinical and analytical parameters were recorded. Cytokine response, bacterial DNA translocation, and several immune-related genes' genotypes were evaluated, along with serum through anti-TNF drug levels. A linear regression analysis controlled by weight and drug regimen was performed.

RESULTS

One hundred nineteen patients were initially considered. Five patients on infliximab and 2 on adalimumab showed antidrug antibodies in serum and were excluded. One hundred twelve patients were finally included (62 on infliximab, 50 on adalimumab). Fourteen patients on infliximab and 15 on adalimumab (22.6% vs 30%, P = 0.37) were receiving an intensified drug regimen. C-reactive protein (CRP), fecal calprotectin, Crohn's Disease Activity Index, leukocyte count, and albumin levels in plasma were not significantly associated with infliximab or adalimumab levels in the multivariate analysis. Serum interleukin-10 (IL-10) levels were directly related to infliximab (Beta = 0.097, P < 0.0001) and adalimumab levels (Beta = 0.069, P = 0.0241). The best multivariate regression model explaining the variability of serum infliximab and adalimumab levels included IL-10. Predicted drug levels by this model robustly fitted with actual drug levels (R2 = 0.841 for infliximab, R2 = 0.733 for adalimumab).

CONCLUSION

Serum IL-10 is significantly related to serum anti-TNF levels in CD patients, showing how the disposition of anti-TNF drugs is significantly influenced by the degree of immunological activation.

Differential effects of corticosteroids and anti-TNF on tumor-specific immune responses: implications for the management of irAEs

Up to 60% of patients treated with cancer immunotherapy develop severe or life threatening immune-related adverse events (irAEs). Immunosuppression with high dose corticosteroids, or tumor necrosis factor (TNF) antagonists in refractory cases, is the mainstay of treatment for irAEs. It is currently unknown what impact corticosteroids and anti-TNF have on the activity of antitumor T cells. In our study, the influence of clinically relevant doses of dexamethasone (corresponding to an oral dose of 10-125 mg prednisolone) and infliximab (anti-TNF) on the activation and killing ability of tumor-infiltrating lymphocytes (TILs) was tested in vitro. Overall, dexamethasone at low or intermediate/high doses impaired the activation (-46 and -62%, respectively) and tumor-killing ability (-48 and -53%, respectively) of tumor-specific TILs. In contrast, a standard clinical dose of infliximab only had a minor effect on T cell activation (-20%) and tumor killing (-10%). A 72-hr resting period after withdrawal of dexamethasone was sufficient to rescue the in vitro activity of TILs, while a short withdrawal did not result in a full rescue. In conclusion, clinically relevant doses of infliximab only had a minor influence on the activity of tumor-specific TILs in vitro, whereas even low doses of corticosteroids markedly impaired the antitumor activity of TILs. However, the activity of TILs could be restored after withdrawal of steroids. These data indirectly support steroid-sparing strategies and early initiation of anti-TNF therapy for the treatment of irAEs in immuno-oncology.