Subclinical Treatment Targets in Rheumatology: Lessons from Randomized Clinical Trials in Rheumatoid Arthritis

Clinical utility of F-18 sodium fluoride PET/CT for estimating disease activity in patients with rheumatoid arthritis

Background

The present study aimed to investigate the clinical implication of F-18 sodium fluoride (NaF) positron emission tomography/computed tomography (PET/CT) for assessing the disease activity of rheumatoid arthritis.

Methods

Seventeen patients with rheumatoid arthritis according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria were prospectively enrolled. All enrolled patients underwent F-18 NaF PET/CT along with physical examination, blood test, and ultrasonography. On PET/CT images, two quantitative parameters, F-18 NaF uptake of the joint (joint SUV) and joint-to-bone uptake ratio, were measured for each of the 28 joints included in calculating the disease activity score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR). The relationship between PET/CT parameters and clinical factors and the predictive values of PET/CT parameters for joints with synovitis and high disease activity were evaluated.

Results

Tender joints (joint SUV, 13.6±8.4; joint-to-bone uptake ratio, 1.70±1.02) and both tender and swollen joints (joint SUV, 13.9±5.4; joint-to-normal bone uptake ratio, 1.81±0.76) had significantly higher joint SUV and joint-to-bone uptake ratio than joints without synovitis (joint SUV, 6.0±2.4; joint-to-bone uptake ratio, 0.74±0.31; P<0.001). On correlation analysis, summed joint SUV (P=0.002, correlation coefficient=0.705) and summed joint-to-bone uptake ratio (P<0.001, correlation coefficient=0.861) of 28 joints showed strong positive correlation with DAS28-ESR after adjustment for age and body mass index. Summed joint SUV showed significant positive correlations with ultrasonography findings (grey scale ultrasonography: P=0.047, correlation coefficient =0.468; power Doppler ultrasonography: P=0.045, correlation coefficient =0.507). On the receiver operating characteristic curve analysis, the sensitivity and specificity for predicting synovitis were 83.2% and 92.7%, respectively, for joint SUV and 81.5% and 90.7%, respectively, for joint-to-bone uptake ratio. Moreover, the summation of both PET/CT parameters of 28 joints showed a diagnostic accuracy of 100.0% for predicting high disease activity in rheumatoid arthritis.

Conclusions

Summed joint uptake on F-18 NaF PET/CT had a strong positive correlation with DAS28-ESR and accurately predicted high disease activity. F-18 NaF PET/CT parameters might be used as an imaging biomarker for disease activity in rheumatoid arthritis.

Trial registration

This study was registered at the Clinical Research Information Service of the Korea (CRIS, http://cris.nih.go.kr/cris/en; registry number, KCT0002597; registered November 2017).

Real world use of biologic drug levels and anti-drug antibodies in patients with psoriasis - does therapeutic drug monitoring have a place in routine clinical practice?

Background: Psoriasis is a chronic disorder with increasing new treatments targeting the T-helper cell (Th)-1/Th17 axis. There remains a subset of patients who experience a primary or secondary failure to biologic treatments.Methods: We present ten patients with psoriasis who failed biologic therapy with measurement of serum drug levels and anti-drug antibody levels (ADAs) with review of the current literature. Our objective was to identify demographic factors, disease status, drug level and ADAs which might correlate with primary and secondary failure.Results: There are a number of factors affecting drug levels in patients with psoriasis on biologics including the presence of ADAs, patient adherence to treatment regimes, pharmacogenetics and the pharmacokinetic properties of the drug following subcutaneous injection. Our results demonstrate that biologic failure is related to low serum drug levels subtherapeutic in 80% of our cohort. Primary failure may correlate with the presence of ADAs but not with serum drug levels. All patients were ANA negative and there remains considerable debate on the utility of routine ANA testing.Conclusions: The role of therapeutic drug monitoring in dermatology remains uncertain and requires further study. We aim to promote debate in the dermatology community as to the utility of therapeutic drug monitoring in routine practice.