Methotrexate Polyglutamate Concentrations as a Possible Predictive Marker for Effectiveness of Methotrexate Therapy in Patients with Sarcoidosis: A Pilot Study.

INTRODUCTION: Methotrexate (MTX), a folate antagonist, is often used as second-line treatment in patients with sarcoidosis. Effectiveness of MTX has large inter-patient variability and at present therapeutic drug monitoring (TDM) of MTX is not possible. Upon administration, MTX is actively transported into cells and metabolized to its active forms by adding glutamate residues forming MTXPG(n=1-5) resulting in enhanced cellular retention. In this study we address the question whether different MTXPG(n) concentrations in red blood cells (RBC) of patients with sarcoidosis after 3 months of MTX therapy correlate with response to treatment. METHODS: We retrospectively included patients with sarcoidosis that had started on MTX therapy and from whom blood samples and FDG-PET/CT were available 3 and 6-12 months after MTX initiation, respectively. FDG-uptake was measured by SUVmax in the heart, lungs and thoracic lymph nodes. Changes in SUVmax was used to determine anti-inflammatory response after 6-12 months of MTX therapy. MTXPG(n) concentrations were measured from whole blood RBC using an LC-MS/MS method. Pearson correlation coefficients were calculated to evaluate the relationship between changes in the SUVmax and MTXPG(n) concentrations. RESULTS: We included 42 sarcoidosis patients treated with MTX (15 mg/week); 31 with cardiac sarcoidosis and 11 with pulmonary sarcoidosis. In MTXPG3 and MTXPG4 a significant negative relation between the absolute changes in SUVmax and MTXPG(n) was found r = - 0.312 (n = 42, p = 0.047) for MTXPG3 and r = - 0.336 (n = 42, p = 0.031 for MTXPG4). The other MTXPG(n) did not correlate to changes in SUVmax. CONCLUSION: These results suggest a relation between MTXPG(n) concentrations and the anti-inflammatory effect in patients with sarcoidosis. Further prospective validation is warranted, but if measuring MTXPG concentrations could predict treatment effect of MTX this would be a step in the direction of personalized medicine.

Prednisone vs methotrexate in treatment naïve cardiac sarcoidosis.

BACKGROUND: Side effects limit the long-term use of glucocorticoids in cardiac sarcoidosis (CS), and methotrexate has gained attention as steroid sparing agent although the supporting evidence is poor. This study compared prednisone monotherapy, methotrexate monotherapy or a combination of both, in the reduction of myocardial Fluorine-18 fluorodeoxyglucose (FDG) uptake and clinical stabilization of CS patients. METHODS AND RESULTS: In this retrospective cohort study, 61 newly diagnosed and treatment naïve CS patients commenced treatment with prednisone (N = 21), methotrexate (N = 30) or prednisone and methotrexate (N = 10) between January 2010 and December 2017. Primary outcome was metabolic response on FDG PET/CT and secondary outcomes were treatment patterns, major adverse cardiovascular events, left ventricular ejection fraction, biomarkers and side effects. At a median treatment duration of 6.2 [5.7-7.2] months, 71.4% of patients were FDG PET/CT responders, and the overall myocardial maximum standardized uptake value decreased from 6.9 [5.0-10.1] to 3.4 [2.1-4.7] (P < 0.001), with no significant differences between treatment groups. During 24 months of follow-up, 7 patients (33.3%; prednisone), 6 patients (20.0%; methotrexate) and 1 patient (10.0%; combination group) experienced at least one major adverse cardiovascular event (P = 0.292). Left ventricular ejection fraction was preserved in all treatment groups. CONCLUSIONS: Significant suppression of cardiac FDG uptake occurred in CS patients after 6 months of prednisone, methotrexate or combination therapy. There were no significant differences in clinical outcomes during follow-up. These results warrant further investigation of methotrexate treatment in CS patients.

Current research topics in FAPI theranostics: a bibliometric analysis.

PURPOSE: The study aimed to provide a comprehensive bibliometric overview of the current scientific publications on fibroblast activation protein inhibitor (FAPI) positron emission tomography imaging and radionuclide therapy. METHODS: A PubMed search was performed to identify all MEDLINE-indexed publications on FAPI imaging and radionuclide therapy. The last update was performed on 31 May 2022. An online database of this literature was created, and hierarchical topic-related tags were subsequently assigned to all relevant studies. Frequency analysis was used to evaluate the distribution of the following characteristics: first author's country of origin, journal of publication, study design, imaging techniques and radiopharmaceutical used, histopathological correlation, the type of cancer, and benign disease/uptake types evaluated. RESULTS: A total of 294 relevant publications on original studies were identified, consisting of 209 (71%) case reports/series and 85 cohort studies (29%). The majority of studies focused on imaging topics, predominantly comparing uptake on FAPI-PET/CT with 2-[18F]FDG-PET/CT, anatomical imaging, and/or histopathology results. 68% of studies focused on malignancies, with gastro-intestinal cancer, hepato-pancreato-biliary cancer, mixed cancers/metastases, lung cancer, sarcoma, head and neck cancer, and breast cancer being the most frequently reported. 42% of studies focused on benign disease categories, with cardiovascular, musculoskeletal, HPB, head and neck, and IgG4-related disease as most common categories. 16/294 (5%) studies focused on radionuclide therapy, with preliminary reports of acceptable toxicity profiles, tumour activity retention, and suggestion of disease control. CONCLUSION: FAPI research is rapidly expanding from diagnostic studies in malignancies and benign diseases to the first reports of salvage radionuclide therapy. The research activity needs to shift now from low-level-of-evidence case reports and series to prospectively designed studies in homogenous patient groups to provide evidence on how and in which clinical situations FAPI theranostics can be of added value to clinical care. We have provided an overview of current research topics to build upon.

In Which Patients with Sarcoidosis Is FDG PET/CT Indicated?

Sarcoidosis is a granulomatous disease of which the etiology remains unknown. The diverse clinical manifestations may challenge clinicians, particularly when conventional markers are inconclusive. From various studies, it has become clear that fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT aids in sarcoidosis care. In this article, an update on FDG PET/CT in sarcoidosis is provided. The use of FDG PET/CT in the diagnostic process of sarcoidosis is explained, especially in determining treatable inflammatory lesions in symptomatic patients with indecisive conventional tests. Furthermore, FDG PET/CT for evaluating the potential benefit of additional inflammatory treatment is described and its use in cardiac sarcoidosis is highlighted.

Quantification of pulmonary disease activity in sarcoidosis measured with 18F-FDG PET/CT: SUVmax versus total lung glycolysis.

BACKGROUND: 18F-FDG PET/CT has proven to be a reliable tool for therapy monitoring in sarcoidosis. Previous PET studies investigated the SUVmax as a marker for disease activity. Total lung glycolysis (TLuG) is a new tool, quantifying the glycolysis of the entire lung. Since SUVmax represents the maximum activity in only one pixel, we hypothesize that TLuG is a more accurate marker for active pulmonary disease and predictor of response than SUVmax. METHODS: In this retrospective cohort study, 27 patients started on infliximab for refractory pulmonary sarcoidosis. Patients received infliximab intravenously monthly at a dose of 5 mg/kg. We performed a lung function test and an 18F-FDG PET/CT before initiation of infliximab and after 6 months of treatment. SUVmax and TLuG were determined in the pre- and post-scan. Change in lung function was correlated with the change in SUVmax and TLuG and was correlated to the initial SUVmax and TLuG to evaluate the predictive value of the initial metabolic activity. RESULTS: ΔSUVmax significantly correlated with ΔFVC (r = - 0.497, p = 0.008) and with ΔFEV1 (r = - 0.467, p = 0.014). Furthermore, ΔTLuG significantly correlated with ΔFVC (r = - 0.430, p = 0.025), ΔFEV1 (r = - 0.532, p = 0.004) and ΔDLCOc (r = - 0.423, p = 0.039). Change in SUVmax and TLuG significantly correlated (r = 0.735, p < 0.001). Initial SUVmax significantly correlated with the change in FVC and DLCOc. In addition, initial TLuG significantly correlated with the change in FEV1 and DLCOc. A SUVmax > 7.5 at initiation of infliximab was predictive for 5% response in FVC, whereas SUVmax > 9.2 was predictive for 5% response in DLCOc. In addition, high TLuG > 4100 at initiation of infliximab was predictive for 5% response in FVC and FEV1 and TLuG > 4500 was predictive for response in DLCOc. CONCLUSION: SUVmax and TLuG are equal in determining the response to infliximab in pulmonary sarcoidosis patients. Furthermore, SUVmax and TLuG at initiation of infliximab can predict change in lung function after treatment. Since TLuG is a more time-consuming tool, we recommend to use SUVmax of the lung parenchyma for response monitoring in pulmonary sarcoidosis.

Efficacy and safety of infliximab biosimilar Inflectra® in severe sarcoidosis.

BACKGROUND: Infliximab, a monoclonal antibody against tumor necrosis factor alpha (TNF-α) is effective third-line therapy in severe sarcoidosis. The originator product of Infliximab, Remicade®, is expensive, limiting universal access. Recently, a less expensive biosimilar of infliximab, Inflectra®, has become available, but the efficacy and tolerability has not been studied in sarcoidosis. METHODS: In this retrospective cohort study, 29 patients treated with the infliximab biosimilar Inflectra®, were analysed. Patients received Inflectra® intravenously monthly at a dose of 5 mg/kg. We measured trough levels before every infusion. Before and after 6 months of induction therapy pulmonary function and disease activity were evaluated using Standardised Uptake Value (SUV) of the 18F-fluorodeoxyglucose by positron emission tomography (18F-FDG PET), soluble interleukin-2 receptor (sIL-2R), angiotensin converting enzyme (ACE) and health-related quality of life (HRQOL). RESULTS: In patients with pulmonary sarcoidosis as main treatment indication (n = 15) the predicted FVC improved with 8.1%, p < 0.05. Furthermore, in the whole group HRQoL improved significantly (p < 0.001), whereas SUVmax and sIL-2R significantly reduced (p < 0.001 and p = 0.001 respectively). Hospitalisation due to infections occurred in four patients. None of the patients discontinued Inflectra® due to side-effects. Furthermore, all patients had detectable trough levels indicating development of neutralizing antibodies. CONCLUSION: Infliximab biosimilar Inflectra® seems effective in the treatment of refractory sarcoidosis with a comparable safety profile to the reference product Remicade®. Inflectra® can be considered as an alternative and less expensive option for patients with refractory sarcoidosis.

99mTc-anti-TNF-α antibody for the imaging of disease activity in pulmonary sarcoidosis.

Infliximab, a monoclonal antibody directed against tumour necrosis factor (TNF)-α, is used in the treatment of refractory sarcoidosis. However, the clinical response is variable and a tool to select responders beforehand is highly desirable. In this study we evaluated scintigraphy with technetium-99m ((99m)Tc)-labelled infliximab for the imaging of disease activity in patients with pulmonary sarcoidosis.10 patients were studied using single photon emission computed tomography/computed tomography (CT) 6 h and 20 h after intravenous administration of 370 MBq of(99m)Tc-infliximab. Correlation analysis was performed between tissue accumulation of(99m)Tc-infliximab and laboratory parameters (including soluble interleukin-2 receptor and angiotensin-converting enzyme), lung function parameters (including forced expiratory volume in 1 s and the diffusing capacity of the lung for carbon monoxide) and(18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT.Analysis showed selective and variable accumulation of(99m)Tc-infliximab in the target tissue. Accumulation correlated positively with all four laboratory parameters and negatively with all four lung function parameters, yielding better correlations than serum TNF-α levels or(18)F-FDG PET/CT.(99m)Tc-infliximab accumulation reflects thein situTNF-α expression in an individual patient and therefore provides valuable information on the presence of the biological target for anti-TNF-α therapy.

Effectiveness of infliximab in refractory FDG PET-positive sarcoidosis.

Inconclusive evidence for the efficacy of infliximab in sarcoidosis hinders the global use of this potentially beneficial drug. To study infliximab efficacy in a clinical setting, we performed a prospective open-label trial in patients refractory to conventional treatment. Patients (n=56) received eight infusions of 5 mg·kg(-1) infliximab. Pulmonary function, disease activity measured by (18)F-fluorodeoxyglucose (FDG) by positron emission tomography (PET) and quality of life were part of the clinical work-up. Infliximab levels were measured before every infusion. After 26 weeks of infliximab treatment, mean improvement in forced vital capacity (FVC) was 6.6% predicted (p=0.0007), whereas in the 6 months before start of treatment, lung function decreased. Maximum standardised uptake value (SUVmax) of pulmonary parenchyma on (18)F-FDG PET decreased by 3.93 (p<0.0001). High SUVmax of pulmonary parenchyma at baseline predicted FVC improvement (R=0.62, p=0.0004). An overall beneficial response was seen in 79% of patients and a partial response was seen in 17% of patients. No correlation between infliximab trough level (mean 18.0 µg·mL(-1)) and initial response was found. In conclusion, infliximab causes significant improvement in FVC in refractory (18)F-FDG PET positive sarcoidosis. Especially in pulmonary disease, high (18)F-FDG PET SUVmax values at treatment initiation predict clinically relevant lung function improvement. These results suggest that inclusion of (18)F-FDG PET is useful in therapeutic decision-making in complex sarcoidosis.

Prediction of relapse after discontinuation of infliximab therapy in severe sarcoidosis.

Infliximab is effective as a third-line therapeutic for severe sarcoidosis; however, long-term efficacy is unknown. The aim of this study was to assess the relapse rate after discontinuation of infliximab in sarcoidosis patients and predict relapse by analysis of the activity marker soluble interleukin (IL)-2 receptor (sIL-2R) and maximum standardised uptake value (SUVmax) of (18)F-fluorodeoxyglucose positron emission tomography (FDG PET). In this retrospective cohort study, the proportion of relapse was analysed using the Kaplan-Meier method and predicting factors were studied using Cox regression. 47 sarcoidosis patients who started infliximab therapy were included in the risk analysis. Kaplan-Meier analysis revealed a median time to relapse of 11.1 months and showed that 25% of the cohort relapsed within 4 months. Both mediastinal SUVmax ≥ 6.0 on FDG PET (hazard ratio 3.77, p<0.001) and serum sIL-2R ≥ 4000 pg · mL(-1) (hazard ratio 2.24, p=0.033) at start of therapy predicted relapse. In multivariate analysis, a mediastinal SUVmax ≥ 6.0 at initiation of therapy was an independent predictor of relapse (hazard ratio 4.33, p<0.001). The majority of patients that discontinued infliximab therapy relapsed. High serum sIL-2R and high SUVmax on FDG PET at initiation of therapy were significant predictors of relapse. These results suggest close monitoring of patients in this category when they discontinue infliximab treatment.

Imaging the inflammatory activity of sarcoidosis.

Accurate assessment of pulmonary and extrapulmonary organ involvement in sarcoidosis is one of the great challenges for clinicians. This assessment includes the evaluation of symptoms and of sarcoidosis activity in a specific organ and its functional consequences. In this review, radiological and nuclear techniques to image the inflammatory activity of sarcoidosis are described, in particular (18)F-FDG positron emission tomography/computed tomography. The current use of this technique in clinical practice is explained, particularly in patients with persistent symptoms, stage IV disease and cardiac sarcoidosis.