Clinical Application of ImmunoPET Targeting Checkpoint Inhibitors

In the last decade, monoclonal antibodies (mAbs) targeting CTLA-4, PD-1, or PD-L1 have been developed and immune checkpoint inhibitors (ICIs) have become the main approach in cancer immunotherapy. However, not all patients benefit from ICI therapy and some are at risk of developing treatment-induced side-effects. These aspects, in parallel with the imaging challenges related to response assessments during immunotherapy, have driven scientific research to the discovery of new predictive biomarkers to individualize patients who could benefit from ICIs. In this context, molecular imaging using PET (positron emission tomography), which allows for whole-body tumor visualization, may be a promising non-invasive method for the determination of patients’ sensitivity to antibody drugs. Several PET tracers, diverse from 2-[18F]FDG (or 2-Deoxy-2-[18F]fluoroglucose), have been developed to image immune checkpoints (ICs) or key elements of the immune system, although most of them are still in preclinical phases. Herein, we present the current state of the ImmunoPET-targeting of IC proteins with mAbs and antibody fragments, with a main focus on the latest developments in clinical molecular imaging studies of solid tumors. Moreover, given the relevance of the immune system and of tumor-infiltrating lymphocytes in particular in the prediction of the benefit of ICIs, we dedicate a portion of this review to ImmunoPET-targeting T cells

Characterization of Mediastinal Bulky Lymphomas with FDG-PET-Based Radiomics and Machine Learning Techniques

Background: This study tested the diagnostic value of 18F-FDG PET/CT (FDG-PET) volumetric and texture parameters in the histological differentiation of mediastinal bulky disease due to classical Hodgkin lymphoma (cHL), primary mediastinal B-cell lymphoma (PMBCL) and grey zone lymphoma (GZL), using machine learning techniques. Methods: We reviewed 80 cHL, 29 PMBCL and 8 GZL adult patients with mediastinal bulky disease and histopathological diagnoses who underwent FDG-PET pre-treatment. Volumetric and radiomic parameters were measured using FDG-PET both for bulky lesions (BL) and for all lesions (AL) using LIFEx software (threshold SUV ≥ 2.5). Binary and multiclass classifications were performed with various machine learning techniques fed by a relevant subset of radiomic features. Results: The analysis showed significant differences between the lymphoma groups in terms of SUVmax, SUVmean, MTV, TLG and several textural features of both first- and second-order grey level. Among machine learning classifiers, the tree-based ensembles achieved the best performance both for binary and multiclass classifications in histological differentiation. Conclusions: Our results support the value of metabolic heterogeneity as an imaging biomarker, and the use of radiomic features for early characterization of mediastinal bulky lymphoma

FAPi-Based Agents in Thyroid Cancer: A New Step towards Diagnosis and Therapy? A Systematic Review of the Literature

(1) Background: Thyroid cancer (TC) is often treated with surgery followed by iodine-131. Up to 50% of the instances of TC lose their avidity to 131I, becoming more aggressive. In this scenario, [18F]FDG PET/CT imaging is used for evaluating the widespread nature of the disease, despite its low sensitivity and a false negative rate of 8–21.1%. A novel class of PET agents targeting the fibroblast activation protein inhibitor (FAPi) has emerged, studied particularly for their potential application to theranostics. (2) Methods: A search of the literature was performed by two independent authors (P.G. and L.E.) using the PubMed, Scopus, Web of Science, Cochrane Library, and EMBASE databases. The following terms were used: “FAP” or “FAPi” or “Fibroblast activating protein” and “thyroid” or “thyroid cancer”, in different combinations. The included papers were original articles, clinical studies, and case reports in the English language. No time limits were used. Editorials, conference papers, reviews, and preclinical studies were excluded. (3) Results: There were 31 papers that were selected. Some studies reported a low or absent FAPi uptake in TC lesions; others reported promising findings for the detection of metastases. (4) Conclusions: The preliminary results are encouraging. FAPI agents are an alternative to [18F]FDG and a promising theranostic tool. However, further studies with a larger population are needed

Predictors of serious adverse events and non-response in cirrhotic patients with primary biliary cholangitis treated with obeticholic acid

Background & Aims Obeticholic acid (OCA) has recently been restricted in patients with primary biliary cholangitis (PBC) with "advanced cirrhosis" because of its narrow therapeutic index. We aimed to better define the predicting factors of hepatic serious adverse events (SAEs) and non-response in cirrhotic patients undergoing OCA therapy. Methods Safety and efficacy of treatment were evaluated in a cohort of consecutive PBC cirrhotic patients started with OCA. OCA response was evaluated according to the Poise criteria. Risk factors for hepatic SAEs and non-response were reported as risk ratios (RR) with 95% confidence intervals (CIs). Results One hundred PBC cirrhotics were included, 97 Child-Pugh class A and 3 class B. Thirty-one had oesophageal varices and 5 had a history of ascites. Thirty-three per cent and 32% of patients achieved a biochemical response at 6 and 12 months respectively. Male sex (adjusted-RR 1.75, 95%CI 1.42-2.12), INR (1.37, 1.00-1.87), Child-Pugh score (1.79, 1.28-2.50), MELD (1.17, 1.04-1.30) and bilirubin (1.83, 1.11-3.01) were independently associated with non-response to OCA. Twenty-two patients discontinued OCA within 12 months: 10 for pruritus, 9 for hepatic SAEs (5 for jaundice and/or ascitic decompensation; 4 for upper digestive bleeding). INR (adjusted-RR 1.91, 95%CI 1.10-3.36), lower albumin levels (0.18, 0.06-0.51), Child-Pugh score (2.43, 1.50-4.04), history of ascites (3.5, 1.85-6.5) and bilirubin (1.30, 1.05-1.56), were associated with hepatic SAEs. A total bilirubin >= 1.4 mg/dl at baseline was the most accurate biochemical predictor of hepatic SAEs under OCA. Conclusions An accurate baseline assessment is crucial to select cirrhotic patients who can benefit from OCA. Although OCA is effective in one third of cirrhotics, bilirubin level >= 1.4 mg/dl should discourage from its use

Frequency of Left Ventricular Hypertrophy in Non-Valvular Atrial Fibrillation

Left ventricular hypertrophy (LVH) is significantly related to adverse clinical outcomes in patients at high risk of cardiovascular events. In patients with atrial fibrillation (AF), data on LVH, that is, prevalence and determinants, are inconsistent mainly because of different definitions and heterogeneity of study populations. We determined echocardiographic-based LVH prevalence and clinical factors independently associated with its development in a prospective cohort of patients with non-valvular (NV) AF. From the "Atrial Fibrillation Registry for Ankle-brachial Index Prevalence Assessment: Collaborative Italian Study" (ARAPACIS) population, 1,184 patients with NVAF (mean age 72 \ub1 11 years; 56% men) with complete data to define LVH were selected. ARAPACIS is a multicenter, observational, prospective, longitudinal on-going study designed to estimate prevalence of peripheral artery disease in patients with NVAF. We found a high prevalence of LVH (52%) in patients with NVAF. Compared to those without LVH, patients with AF with LVH were older and had a higher prevalence of hypertension, diabetes, and previous myocardial infarction (MI). A higher prevalence of ankle-brachial index 640.90 was seen in patients with LVH (22 vs 17%, p = 0.0392). Patients with LVH were at significantly higher thromboembolic risk, with CHA2DS2-VASc 652 seen in 93% of LVH and in 73% of patients without LVH (p <0.05). Women with LVH had a higher prevalence of concentric hypertrophy than men (46% vs 29%, p = 0.0003). Logistic regression analysis demonstrated that female gender (odds ratio [OR] 2.80, p <0.0001), age (OR 1.03 per year, p <0.001), hypertension (OR 2.30, p <0.001), diabetes (OR 1.62, p = 0.004), and previous MI (OR 1.96, p = 0.001) were independently associated with LVH. In conclusion, patients with NVAF have a high prevalence of LVH, which is related to female gender, older age, hypertension, and previous MI. These patients are at high thromboembolic risk and deserve a holistic approach to cardiovascular prevention