Association of Serum Tocilizumab Trough Concentrations with Clinical Disease Activity Index Scores in Adult Patients with Rheumatoid Arthritis

Towards Personalized Medicine in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, incurable, multisystem, inflammatory disease characterized by synovitis and extra-articular features. Although several advanced therapies targeting inflammatory mechanisms underlying the disease are available, no advanced therapy is universally effective. Therefore, a ceiling of treatment response is currently accepted where no advanced therapy is superior to another. The current challenge for medical research is the discovery and integration of predictive markers of drug response that can be used to personalize medicine so that the patient is started on "the right drug at the right time". This review article summarizes our current understanding of predicting response to anti-rheumatic drugs in RA, obstacles impeding the development of personalized medicine approaches and future research priorities to overcome these barriers.

Early Exposure of Kidney Transplant Recipients with Chronic Antibody-Mediated Rejection to Tocilizumab-A Preliminary Study

Tocilizumab prevents clinical worsening of chronic antibody-mediated rejection (CAMR) of kidney transplant recipients. Optimization of this treatment is necessary. We identified the determinants of early tocilizumab exposure (within the first three months) and investigated the relationship between early plasma tocilizumab exposure and graft function. Patients with CAMR who started treatment with tocilizumab were retrospectively included. Demographic, clinical, and biological determinants of the tocilizumab trough concentration (Cmin) were studied using a linear mixed effect model, and the association between early exposure to tocilizumab (expressed as the sum of Cmin over the three first months (M) of treatment (ΣCmin)) and the urinary albumin-to-creatinine ratio (ACR) determined at M3 and M6 were investigated. Urinary tocilizumab was also measured in seven additional patients. Seventeen patients with 51 tocilizumab Cmin determinations were included. In the multivariate analysis, the ACR and time after tocilizumab initiation were independently associated with the tocilizumab Cmin. The ΣCmin was significantly lower (p = 0.014) for patients with an ACR > 30 mg/mmol at M3 and M6 than for patients with an ACR < 30 mg/mmol. Tocilizumab was detected in urine in only 1/7 patients. This study is the first to suggest that early exposure to tocilizumab may be associated with macroalbuminuria within the first six months in CAMR patients.

Efficacious switching from subcutaneous to intravenous tocilizumab in patients with non-infectious non-anterior uveitis

PURPOSE

The efficacy of tocilizumab in refractory chronic noninfectious uveitis has been previously reported, but no data comparing intravenous and subcutaneous tocilizumab in uveitis are available.

RESULTS

We report a case series of patients with chronic noninfectious uveitis with incomplete efficacy of subcutaneous tocilizumab, improved after switching to intravenous routes. Improvement of visual acuity was observed with intravenous tocilizumab for all patients. Half of the patients could stop corticosteroids. Rapid efficacy of intravenous tocilizumab was observed, between 2 and 3 months.

CONCLUSION

In uveitis, tocilizumab administration could be optimized by a switching from a subcutaneous to an intravenous administration route.

Tailored therapeutic decision of rheumatoid arthritis using proteomic strategies: how to start and when to stop?

Unpredictable treatment responses have been an obstacle for the successful management of rheumatoid arthritis. Although numerous serum proteins have been proposed, there is a lack of integrative survey to compare their relevance in predicting treatment outcomes in rheumatoid arthritis. Also, little is known about their applications in various treatment stages, such as dose modification, drug switching or withdrawal. Here we present an in-depth exploration of the potential usefulness of serum proteins in clinical decision-making and unveil the spectrum of immunopathology underlying responders to different drugs. Patients with robust autoimmunity and inflammation are more responsive to biological treatments and prone to relapse during treatment de-escalation. Moreover, the concentration changes of serum proteins at the beginning of the treatments possibly assist early recognition of treatment responders. With a better understanding of the relationship between the serum proteome and treatment responses, personalized medicine in rheumatoid arthritis will be more achievable in the near future.

Effect of body mass index on treatment response of biologic-/targeted synthetic-DMARDs in patients with rheumatoid arthritis, psoriatic arthritis and axial spondyloarthritis. A systematic review

BACKGROUND

Overweight and/or obese patients with inflammatory arthritis (IA) have higher disease activity and lower chances of achieving and/or maintaining the treatment targets. Weight/obesity also appears to negatively affect the response to tumor necrosis factor (TNF) inhibitors in patients with IA, including rheumatoid arthritis -RA, psoriatic arthritis -PsA, axial spondyloarthritis -AxSpA. We conducted a systematic literature review (SLR) for the effect of weight/body-mass-index (BMI) in the efficacy of all approved b- and targeted-synthetic (ts)- DMARDs for the treatment of IA.

METHODS

For this PROSPERO-registered SLR, we searched PubMed, Scopus and Cohrane-Library from inception up to June 21st 2022. Clinical-trials (randomized and non-randomized) and observational studies of RA, PsA or AxSpA patients that reported the effect of weight/BMI on response (all possible outcomes) to b/ts-DMARDs were included. Risk-of-bias was assessed via RoB2-Cochrane-tool and Newcastle-Ottawa-scale for randomized and non-randomized studies, respectively.

FINDINGS

Out of 996 references, 75 eventually fulfilled the inclusion criteria (of which 10 studies were retrieved through manual-search). Among the included studies (TNF-inhibitors: 34, IL-12/23 inhibitors: 4, IL-23 inhibitor: 1, IL-17 inhibitors: 7, tocilizumab: 18, abatacept: 8, rituximab: 3, JAK-inhibitors: 5), most had medium RoB. Efficacy of TNF-inhibitors was affected by BMI in all forms of IA. Data are not robust to compare the effect among various TNF-inhibitors. In contrast, favorable results of IL-23 and IL-17 inhibitors did not appear to be influenced by increased BMI in PsA or AxSpA patients. Similar evidence exists for tocilizumab (in RA) and for abatacept (in RA and PsA), while no conclusion can be drawn for rituximab. More data are needed for JAK-inhibitors, although the effect of weight/BMI does not seem to be significant so far.

INTERPRETATION

Weight/BMI should be considered in the treatment-plan of patients with IA, with its effect being more pronounced for TNF-inhibitors compared to other b/ts-DMARDs.

Baseline erythrocyte sedimentation rate level predicts long-term inhibition of radiographic progression by tocilizumab: the KURAMA cohort

The short-term effect of tocilizumab (TCZ) on the radiographic progression of rheumatoid arthritis has been reported; however, reports on its long-term effects are scarce. In this study, we aimed to evaluate its long-term effects on joint destruction in patients who had been treated with TCZ for at least two years and for whom X-rays were available. Radiographic progression was evaluated with modified Total Sharp Score (mTSS), and structural remission was defined as the mean annual change in mTSS ≤0.5. Of the 59 patients included in this study (median age, 62 years; female, 81.4%), 34 patients (57.6%) achieved structural remission. Patients who achieved structural remission were relatively younger (59 years vs. 64 years, p = .06), had relatively higher proportion of anti-citrullinated protein antibody positivity (91.2% vs. 72.0%, p = .08), relatively lower C-reactive protein level (0.6 mg/dL vs. 2.2 mg/dL, p = .05), and significantly lower erythrocyte sedimentation rate (ESR) level (28.0 mm/h vs 65.5 mm/h, p = .003) than those who did not. Multivariate logistic regression analysis demonstrated that the baseline ESR level was significantly associated with structural remission (odds ratio, 0.98; 95% confidence interval: 0.96-0.99, p = .049). The baseline ESR level is a critical determinant of the long-term effect of TCZ on joint destruction.

EULAR points to consider for therapeutic drug monitoring of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases

OBJECTIVE

To develop EULAR points-to-consider for therapeutic drug monitoring (TDM) of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases (RMDs).

METHODS

The points-to-consider were developed in accordance with EULAR standardised operation procedures by a multidisciplinary task force from eight European countries, based on a systematic literature review and expert consensus. Level of evidence and strength of the points-to-consider were determined, and mean levels of agreement among the task force were calculated using a 10-point rating scale.

RESULTS

Six overarching principles and 13 points-to-consider were formulated. The level of agreement among the task force for the overarching principles and points-to-consider ranged from 8.4 to 9.9.The overarching principles define TDM and its subtypes, and reinforce the underlying pharmacokinetic/pharmacodynamic principles, which are relevant to all biopharmaceutical classes. The points-to-consider highlight the clinical utility of the measurement and interpretation of biopharmaceutical blood concentrations and antidrug antibodies in specific clinical scenarios, including factors that influence these parameters. In general, proactive use of TDM is not recommended but reactive TDM could be considered in certain clinical situations. An important factor limiting wider adoption of TDM is the lack of both high quality trials addressing effectiveness and safety of TDM and robust economic evaluation in patients with RMDs. Future research should focus on providing this evidence, as well as on further understanding of pharmacokinetic and pharmacodynamic characteristics of biopharmaceuticals.

CONCLUSION

These points-to-consider are evidence-based and consensus-based statements for the use of TDM of biopharmaceuticals in inflammatory RMDs, addressing the clinical utility of TDM.

LC-MS/MS method for the quantitation of serum tocilizumab in rheumatoid arthritis patients using rapid tryptic digestion without IgG purification

The quantitation of serum tocilizumab using liquid chromatography tandem-mass spectrometry (LC-MS/MS) method has not been widely applied in clinical settings because of its time-consuming and costly sample pretreatments. The present study aimed to develop a validated LC-MS/MS method for detecting serum tocilizumab by utilizing immobilized trypsin without an immunoglobulin G purification step and evaluate its applicability in the treatment of rheumatoid arthritis (RA) patients administered intravenously or subcutaneously with tocilizumab. The tocilizumab-derived signature peptide was deciphered using a nano-LC system coupled to a hybrid quadrupole-orbitrap mass spectrometer. The serum tocilizumab was rapidly digested by immobilized trypsin for 30 min. The chromatographic peak of the signature peptide and that of the internal standard were separated from the serum digests for a total run time of 15 min. The calibration curve of serum tocilizumab concentration was linear with a range of 2-200 μg/mL. The intra- and inter-day accuracy and relative standard deviation (RSD) were 90.7%-109.4% and <10%, respectively. The serum tocilizumab concentrations in the RA patients receiving intravenous and subcutaneous injections were 5.8-28.9 and 2.4-63.5 μg/mL, respectively. The serum tocilizumab concentrations using the current method positively correlated with those using the enzyme-linked immunosorbent assay, although a systematic error was observed between these methods. In conclusion, a validated LC-MS/MS method with minimal sample pretreatments for monitoring serum tocilizumab concentrations in RA patients was developed.

Therapeutic drug monitoring of biopharmaceuticals in inflammatory rheumatic and musculoskeletal disease: a systematic literature review informing EULAR points to consider

The objectives of this review were to collect and summarise evidence on therapeutic drug monitoring (TDM) of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases and to inform the EULAR Task Force for the formulation of evidence-based points to consider. A systematic literature review (SLR) was performed, covering technical aspects and (clinical) utility of TDM, to answer 13 research questions. MEDLINE, Embase and Cochrane were searched until July 2020. American College of Rheumatology and EULAR abstracts were also considered for inclusion. Data were extracted in evidence tables and risk of bias assessment was performed. For the search on technical aspects, 678 records were identified, of which 22 papers were selected. For the clinical utility search, 3846 records were identified, of which 108 papers were included. Patient-related factors associated with biopharmaceutical blood concentrations included body weight, methotrexate comedication and disease activity. The identification of a target range was hampered by study variability, mainly disease activity measures and study type. Evidence was inconsistent for multiple clinical situations in which TDM is currently applied. However, for some particular scenarios, including prediction of future treatment response, non-response to treatment, tapering and hypersensitivity reactions, robust evidence was found. There is currently no evidence for routine use of proactive TDM, in part because published cost-effectiveness analyses do not incorporate the current landscape of biopharmaceutical costs and usage. This SLR yields evidence in favour of TDM of biopharmaceuticals in some clinical scenarios, but evidence is insufficient to support implementation of routine use of TDM.

Tocilizumab Trough Levels Variability in Kidney-Transplant Candidates Undergoing Desensitization

The presence of anti-HLA antibodies is an increasing challenge in kidney transplantation. Tocilizumab (TCZ), a monoclonal antibody targeting the interleukin-6 receptor (IL-6R), has been proposed to complement conventional desensitization therapy. We aimed to describe TCZ plasma trough concentrations and their variability and to investigate the link between TCZ concentration and the evolution of anti-HLA antibodies. Sensitized kidney-transplant candidates treated monthly with TCZ (8 mg/kg) for desensitization were retrospectively included. TCZ concentrations were determined by liquid chromatography-tandem mass spectrometry. Seventy-four TCZ concentrations from 10 patients were analyzed. The TCZ trough concentration ranged from <1.0 to 52.5 mg·L−1, with a median of 25.6 mg·L−1 [25th–75th percentiles: 13.2–35.3 mg·L−1). The inter- and intra-individual coefficients of variation were 55.0% and 33.0%, respectively. The TCZ trough concentration was not related to IL-6 (rho = −0.46, p = 0.792), soluble IL-6R (rho = −0.81, p = 0.65) concentrations or reduction of anti-HLA antibodies (mixed-effects model adjusting, effect of TCZ trough concentration: rho = −0.004, p = 0.26). The individual median TCZ concentration tended to be associated with the number of antibodies, with an initial MFI > 3000 that dropped to <3000 after TCZ treatment (rho = 0.397, p = 0.083). TCZ trough concentrations in kidney-transplant candidates treated for desensitization were highly variable. Further studies on larger cohorts are needed to study the possible link between TCZ concentrations and the reduction of anti-HLA antibodies.

Variability of rituximab and tocilizumab trough concentrations in patients with rheumatoid arthritis

Patients with rheumatoid arthritis (RA) are eligible for treatment with therapeutic monoclonal antibodies (mAbs) that target tumor necrosis factor α (TNFα), as well as others, such as rituximab (RTX) and tocilizumab (TCZ). Although pharmacokinetic variability and the link between concentration-clinical response of anti-TNFα mAbs have been well-described, little is known about RTX and TCZ. We aimed to evaluate the variability of RTX and TCZ serum concentrations in RA patients treated in second-line and the relationship between RTX/TCZ concentrations and the clinical response. Serum mAb trough concentrations of RA patients treated with RTX (n = 35) or TCZ (n = 46) were determined at week 24 by liquid chromatography-tandem mass spectrometry. The clinical response was assessed at week 24 by the change in the disease activity score in the 28 joints-erythrocyte sedimentation rate from baseline (ΔDAS28-Erythrocyte Sedimentation Rate) and according to the European League Against Rheumatism (EULAR) recommendations. RTX and TCZ trough concentrations were highly variable, with a coefficient of variation of 171.3% for RTX (median [10th-90th percentiles]: <1.0 µg/mL [<1.0-5.1]) and 132.6% for TCZ (median [10th-90th percentiles]: 5.4 µg/mL [<1.0-27.8]). Univariate analysis did not identify any determinants of such variability, except cotreatment with methotrexate, which was associated with lower RTX concentrations (P = 0.03). The response to treatment was not related to the RTX or TCZ trough concentration. RTX and TCZ trough concentrations at 24 weeks were highly variable in RA patients treated in the second line, without any link concentration-clinical response having been demonstrated.

Predicting treatment response to IL6R blockers in rheumatoid arthritis

Patients with severe, active RA who have not responded to conventional therapy may receive biological disease modifying anti-rheumatic drugs (bDMARDs). However, 40% of cases do not achieve complete disease control, resulting in a negative impact on patient quality of life and representing a waste of healthcare resources. Ongoing research seeks to establish biomarkers, which can be used to predict treatment response to biologics in RA to enable more targeted approaches to treatment. However, much of the work has focused on one class of biologic drug, the TNF inhibitors (TNFi). Here, we will review the current state of research to identify biomarkers predictive of response to the class of bDMARDs targeting the IL6R. While success has been limited thus far, serum drug and low ICAM1 levels have shown promise, with associations reported in independent studies. The challenges faced by researchers and lessons learned from studies of TNFi will be discussed.