Background/Objectives: Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality worldwide. Immune checkpoint inhibitors (ICIs) have transformed treatment paradigms, but assessing response remains challenging due to atypical patterns such as pseudoprogression, hyperprogression and dissociated response. Conventional evaluation criteria, such as RECIST 1.1, may not fully capture these patterns, leading to potential misclassification and premature therapy discontinuation. This review explores the role of 18F-FDG PET/CT in assessing immunotherapy response and highlights novel imaging criteria to enhance clinical decision-making. Methods: A systematic literature review was conducted across PubMed, Web of Science, Scopus, and Cochrane Library, selecting relevant studies published between 2013 and 2024. The review focuses on the strengths and limitations of PET-based imaging in monitoring NSCLC immunotherapy outcomes. Specific attention was given to evolving evaluation frameworks, including iRECIST, PERCIST, imPERCIST, and iPERCIST, as well as metabolic biomarkers such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Results: Compared with anatomical-based assessment, metabolic imaging using 18F-FDG PET/CT may offer deeper insights into tumor behavior during immunotherapy. PET-derived parameters seem to improve the detection of immune-related response patterns, providing a more refined approach to differentiate true progression from pseudoprogression. Emerging evidence indicates that metabolic biomarkers such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) could serve as useful predictors of therapeutic efficacy and support treatment adaptation. Nevertheless, current findings are mainly based on small, heterogeneous, and predominantly retrospective studies, with variable PET timing and threshold definitions that limit the generalizability of these results. Conclusions: 18F-FDG PET/CT represents a promising complementary tool for assessing immunotherapy response in NSCLC. Its integration with advanced imaging criteria and metabolic tumor biomarkers may enhance response evaluation and assist clinical decision-making. Nonetheless, the current evidence remains preliminary, and further standardization and large prospective validation studies are required before its routine implementation in clinical practice.

Background The increasing number of patients treated with biologic therapies, the extending duration and costs of these treatments necessitate the development of strategies to the tapering or discontinuation of biologics in rheumatoid arthritis (RA) patients with long-standing remission on these agents. As flares occur frequently in patients in whom biologics are stopped, the identification of predictive markers for the preservation of long-standing remission after discontinuation is an important need. Several microRNA-s (miRNA) and SuPar (soluble urokinase plasminogen activator receptor) have been found to correlate with disease activity, and to be sensitive biomarkers of treatment response. Objectives The authors' aim was to prospectively follow the disease course after the permanent cessation of biologics, and to identify clinical and biochemical predictors of sustained biologic-free remission. Methods In this prospective, multicentre, controlled trial, eligible RA patients were treated with anti-TNF or IL6R-blocker, had a minimum of one-year remission (DAS-28<2.6), and no corticosteroid therapy. After discontinuation of the biologics, DAS28, HAQ, ESR and CRP were recorded at baseline, month 1, 3 and every 3 months thereafter. SuPar and soluble miRNA146a, miRNA16, miRNA155, miRNA223 and miRNA346 levels were measured by ELISA or QRT-PCR, respectively at baseline, month 1, 3, 6 and at relapse, if occurred. In the control group (n=5), patients had sustained remission on biologics, and had similar demographic and serological parameters, but the biologic therapy was not stopped. Results At present 23 patients with RA have been enrolled (average age: 59,95/35–79/ years).The mean duration of biologic therapy was 54,04 (25–84) months, and was started an average of 62,3 months (1–240 months) after the diagnosis. After the discontinuation, 14 patients are in biologic-free remission for an average of 5,21 (1–16 months). Relapse occurred in 9 cases an average of 5,20 (2–12) months after the discontinuation. miRNA146a levels at stop were higher in relapsers than in those with sustained remission (relative expression to cel miR39: -3,08 vs -7,87, p=0.009) (n=8 stopped patients, n=1 control). Circulating miRNA223, miRNA16, miRNA155 and miRNA346 levels were comparable in the two drug-cessation groups. SuPar levels were not different in the 12 patients in remission and 7 relapsers, in whom the measurements have been performed so far. Conclusions In RA patients with long-term remission on anti-TNF or IL6R-blocker, elevated level of miRNA146a may indicate a higher risk of relapse after stopping biologics. Further follow-up and the involvement of more patients are currently underway, and this may identify further predictive markers. Toldi G, Kádár G et al. Soluble urokinase plasminogen activator receptor (suPAR) in the asessment of inflammatory activity of rheumatoid arthritis in patients in remission. ClinChem Lab Med 51(2):327–332. 2013 Disclosure of Interest None declared