Molecular Imaging and Biology最新文献

Rationale: Bintrafusp alfa is a first-in-class bifunctional fusion protein composed of the extracellular domain of the human transforming growth factor β receptor II (TGF-βRII or TGF-β "trap") and human immunoglobulin 1 antibody which blocks programmed cell death ligand 1 (PD-L1). This trial aimed to investigate the biodistribution of ⁸⁹Zr-bintrafusp alfa in patients with NSCLC with PD-L1 expressing tumors.

Methods: Five lung cancer patients were recruited with PD-L1 staining more than 1% of tumor cells. Patients underwent ⁸⁹Zr-bintrafusp alfa intravenous infusion (100 mg IV) on Day 1 followed by sequential PET imaging to determine the biodistribution of ⁸⁹Zr-bintrafusp alfa. Patients then received treatment with bintrafusp alfa (1200 mg IV) on day 15 and 29, with the latter including further ⁸⁹Zr-bintrafusp alfa to determine the effects of bintrafusp alfa treatment on receptor occupancy. Patients continued with bintrafusp alfa monotherapy, or in combination with chemotherapy for those without objective response to monotherapy, until disease progression or unacceptable toxicity. The study stopped after five patients due to the overall cessation of the bintrafusp alfa program.

Results: ⁸⁹Zr-bintrafusp alfa imaging was feasible and well tolerated. All patients showed tumor specific uptake without normal tissue uptake. There was no correlation between uptake and tissue PD-L1 expression or outcomes, likely due to sample size. Inter- and intra-patient heterogeneity was observed and optimal treatment regimens will need to address this in future.

Conclusions: ⁸⁹Zr-bintrafusp alfa imaging is safe, feasible and provides relevant tumor targeting information for patient selection and treatment.

Purpose: This study aimed to assess the feasibility of intraoperative fluorescence imaging using the PSMA-targeted fluorescent tracer OTL78 for detecting lymph node metastases during pelvic lymph node dissection (PLND) in patients undergoing staging or salvage surgery for prostate cancer.

Procedures: In a prospective pilot study, six patients scheduled for robot-assisted PLND received a single intravenous infusion of OTL78 at a dose of either 0.06 mg/kg or 0.03 mg/kg, administered 1-2 h prior to surgery. Intraoperatively, lymph node clusters were evaluated using fluorescence imaging. Post-surgical histopathological analysis and immunohistochemistry were performed to confirm tumor presence and PSMA overexpression in fluorescent nodes. The primary outcome was the feasibility of fluorescence imaging in detecting metastatic lymph nodes during PLND.

Results: Fluorescence imaging demonstrated a sensitivity of 66.7% and specificity of 91.7% for identifying metastatic lymph nodes. The positive predictive value was 66.7%, and the negative predictive value was 91.7%. Metastasized lymph nodes (MLN) exhibited significantly higher median fluorescence intensity (MFI) than benign lymph nodes (BLN): 0.51 [IQR 0.11-0.74] vs. 0.06 [IQR 0.03-0.12], p = 0.024. Immunohistochemistry confirmed PSMA overexpression in fluorescent malignant regions. No adverse reactions to the tracer were reported.

Conclusions: Intraoperative fluorescence imaging with the tracer OTL78 is a feasible technique for identifying metastatic lymph nodes during PLND. Fluorescence guidance may assist in detecting small metastatic deposits within nodal clusters that are otherwise difficult to localize. Larger studies are needed to validate these findings and optimize the imaging protocol for broader clinical use.

Background/objectives: Immune checkpoint blockade (ICB) therapy has been ineffective in glioblastoma (GBM) that recurs following standard-of-care resection and chemoradiation of the primary tumor. Herein, we investigate whether the delayed effect of intracranial radiation alters the tumor lesion metabolic profile.

Methods: Naïve (non-irradiated) GL261 tumor cells were implanted into the brains of C57BL/6 mice. Brains of one cohort were hemispherically irradiated six weeks prior to implantation, ultimately resulting in ICB refractory GBM. Brains of the control cohort were not irradiated. Following subcutaneous infusion of [6,6-²H₂] glucose (Glc), single voxel deuterium metabolic imaging (DMI) monitored Glc uptake and the production of semi-heavy water (HOD), ²H₂-lactate (Lac) and the 50/50 mix of [²H₂-glutamate + ²H₂-glutamine] (Glx).

Results: GL261 tumors growing in previously irradiated brain showed reduced Warburg effect (aerobic glycolysis; glucose → lactate) and greater TCA cycle activity (respiration, oxidative phosphorylation) relative to tumors growing in non-irradiated brain as evidenced by cohort differences in the ratios Glx/Lac (p < 0.01), Glx/Glc (p < 0.02), and Lac/Glc (p < 0.01).

Conclusions: A metabolic program skewed toward oxidative phosphorylation and away from glycolysis has been associated with immune dysfunction. This study documents such a skewed metabolic state in ICB refractory GL261 GBM growing in irradiated brain (tumors were not irradiated) compared to control brain.

Objective: To investigate the feasibility of early dynamic 2-[¹⁸F]-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) imaging in predicting epidermal growth factor receptor (EGFR) and tumor protein 53 (TP53) mutation status in lung adenocarcinoma (AC).

Methods: In total, 81 patients with lung nodules underwent early dynamic PET (10 min after injection) and late static PET (60 min after injection), and 41 (18 male, 23 female; mean age 64 ± 10 years) with confirmed AC were included in the final analysis. Dynamic images were reconstructed into 25 frames, and time-to-activity curves were generated. An irreversible two-tissue compartment model was used to derive kinetic parameters (K_1, k₂, k₃, Ki, and MR_FDG). EGFR and TP53 mutation statuses were determined via histological analysis. Statistical tests, including the Wilcoxon rank-sum test, Kruskal-Wallis H test, and Spearman's correlation, were used to assess differences and associations among groups. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the predictive performance.

Results: In patients with AC, k₃, Ki, and MR_FDG were strongly correlated with SUV_max (r = 0.821, 0.862, and 0.778, respectively; all P < 0.001). SUV_max, k₃, Ki, and MR_FDG differed significantly between patients with AC and SCC, as well as across TNM and pathological stage subgroups (P < 0.05). SUV_max and k₃ were significantly lower in the EGFR-positive group, while Ki was higher in the TP53-positive group (P < 0.05). AUCs for predicting EGFR mutation were 0.718 (SUV_max) and 0.776 (k₃), and 0.703 (Ki) for TP53 mutation.

Conclusions: Early dynamic ¹⁸F-FDG PET/CT may serve as a valuable non-invasive tool for predicting EGFR and TP53 mutation status in AC, for screening patients for targeted therapy.

Atherosclerosis (AS) is a chronic condition defined by the accumulation of plaque fundamentally resulting from the deposition of low-density lipoprotein and fibrous compounds within injured arteries. Current treatments for atherosclerosis are effective, but the complex and not fully understood underlying mechanisms limit their effectiveness. Moreover, early detection of AS continues to be a real challenge. Innovative therapeutic approaches, such as the application of nanomedicines and theragnostic, are increasingly attracting the interest of researchers globally. Gold nanoparticles (AuNPs) exhibit significant potential as theragnostic agents in the context of atherosclerosis, providing both diagnostic and therapeutic functionalities. This review will discuss current strategies utilizing AuNPs and explore potential future advancements involving theragnostic AuNPs that may aid in addressing AS.

Purpose: Immune checkpoint inhibition has shown promising results in malignant melanoma, but not all patients respond equally well, necessitating early, accurate monitoring of immunotherapy response. [¹⁸F]FDG-PET/CT aids in characterising therapy response beyond morphology, but validated imaging biomarkers for immunotherapy response remain scarce. This study investigated three-time point [¹⁸F]FDG-PET/CT to monitor combined anti-PD-L1/anti-CTLA-4 immunotherapy in murine melanoma allografts and compared quantitative in vivo imaging biomarkers with ex vivo biomarkers from multiparametric immunohistochemistry at each time point.

Procedures: Melanoma cells (B16-F10) were injected subcutaneously into C57BL/6 mice (n = 40). Seven days post-inoculation, baseline [¹⁸F]FDG-PET/CT was conducted. Animals were randomized into two groups; the therapy group received 5 i.p.-injections of anti-PD-L1/anti-CTLA-4 (20 µg/kg) on days 7, 9, 11, 13 and 15 after tumor cell inoculation. The control group received sham treatment. PET/CT was performed at baseline (day 7 post inoculation), follow-up 1(day 13; FU-1) and follow-up 2 (day 19; FU-2). Tumor allografts were harvested at each time point for immunohistochemistry (CD8, Ki-67, TUNEL) to validate imaging parameters (MTV, SUVmax).

Results: At FU-1, the therapy group exhibited significantly lower MTV than the control group (p = 0.004). At FU-2, MTV and SUVmax were significantly lower (MTV: p = 0.008; SUVmax: p = 0.0003) compared to controls. Ex vivo analysis revealed significant anti-tumor effects in the therapy group, with higher apoptosis rates (FU-1: p = 0.012; FU-2: p = 0.001), more CD8-positive T-cells (FU-2: p = 0.003) and lower tumor cell proliferation (FU-1: p = 0.012; FU-2: p = 0.012).

Conclusions: Multi-time point [¹⁸F]FDG-PET/CT allowed for early non-invasive monitoring of combined anti-PD-L1/anti-CTLA-4 immunotherapy in experimental melanomas, validated by multiparametric immunohistochemistry with significant pro-immunogenic, pro-apoptotic and anti-proliferative effects.

Purpose: Peptide receptor radionuclide therapy (PRRT) with Lu-177-DOTATATE is an established treatment option for neuroendocrine tumors (NETs) and has been extended to other somatostatin receptor (SSTR)-expressing tumors. We aimed to determine its efficacy and safety profile in patients with advanced radioiodine-refractory differentiated thyroid carcinoma (DTC).

Methods: Seven radioiodine-refractory DTC patients undergoing at least two cycles of PRRT were included. Patients were subdivided into continuous treatment (defined as sequential application of PRRT; 5/7 (71.4%)) vs. discontinuous treatment (with at least one-year PRRT-free interval; 2/7 (28.6%)). Baseline SSTR PET was analyzed to determine patients' eligibility for PRRT. Response was assessed by tumor control as defined by stable (± 30.0%) or decreasing (≥ 30.0%) total tumor volume (PET-derived TTV), thyroglobulin (Tg) and RECIST 1.1 criteria.

Results: SSTR PET showed discernible high uptake (maximum standardized uptake values, 10.4 ± 8.6) in metastases, in particular in the skeleton. Continuous PRRT showed variable tumor control (stable disease / response; TTV: 3/5 (60.0%); Tg: 2/5 (40.0%); RECIST 1.1: 3/5 (60.0%)). All patients undergoing discontinuous PRRT exhibited concordant stable disease upon first follow-up and renewed tumor control upon reinitiating PRRT (RECIST 1.1; decreasing TTV and Tg levels). No Common Terminology Criteria for Adverse Events (CTCAE) Grade 3-5 events occured in both groups.

Conclusion: In advanced radioiodine-refractory DTC, PRRT may be beneficial even after treatment interruptions, without major side effects. Given the small cohort and retrospective design, further prospective studies are needed to optimize PRRT strategies in DTC, in particular in a rechallenge scenario.

Purpose: In this study, we report the development and characterization of a copper-64 (⁶⁴Cu) radiolabeled anti-EphA2 minibody (Mb) for pre-treatment characterization of antigen expression via Positron Emission Tomography (PET). Minibodies, ≈85 kDa molecular weight antibody fragments, are advantageous as targeting molecules due to accelerated serum clearance which enables imaging at earlier time points relative to the parent IgG. As EphA2, a tyrosine kinase receptor, is overexpressed in various cancer types with minimal expression in normal tissue, rapid quantification of EphA2 expression could be beneficial for patient stratification.

Procedures: Recombinantly produced anti-EphA2-Mb was evaluated for purity, stability, affinity, and in vivo target localization. Following bifunctional chelator conjugation, radiolabeling with ⁶⁴Cu and evaluating purity, stability and immunoreactivity of resultant radioimmunoconjugate, [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb, 11.1 MBq (300 μCi) and 0.2 MBq (5 μCi) doses were administered to HT1080-fibrosarcoma-bearing nude mice for in-vivo PET imaging and ex-vivo biodistribution analyses respectively at 4 and 24 h post-injection (p.i.). Antigen-specificity was assessed via a blocked control group which received the dose co-administered with non-radiolabeled anti-EphA2-Mb.

Results: Anti-EphA2-Mb produced via recombinant protein expression was pure, stable and had high binding affinity to human EphA2 antigen (K_D = 0.63 ± 0.24 nM). When labeled with ⁶⁴Cu via NOTA, [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb had high purity, in-vitro stability in PBS and mouse serum up to 24 h, and high immunoreactivity. On administering to tumor-bearing mice, [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb exhibited rapid tumor targeting with 25.53±2.92%ID/g at 4 h, and 22.13±7.68%ID/g at 24 h p.i. Competitive inhibition reduced tumor uptake (11.24±0.88%D/g, 24 h p.i., p = 0.0286). There was minimal uptake of the radiotracer in non-target tissues, except kidney and liver, and fast clearance from the blood, with high tumor to blood ratios. Tumor SUV_mean values obtained from region of interest (ROI) Quantification of the PET images were 1.13±0.03 and 1.08±0.06 at 4 and 24 h respectively.

Conclusion: Our findings demonstrate that anti-EphA2-Mb is an excellent targeting molecule, and [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb is a promising immunoPET agent with potential for use for other theranostic applications.

Preclinical biodistribution studies are required at an early stage of radiopharmaceutical development to determine tracer pharmacokinetics in clinically relevant animal models of human diseases. When combined with quantitative analysis from non-invasive imaging, biodistribution experiments provide essential data on the uptake, retention, binding specificity, metabolism, and clearance of radiotracers in both target and non-target tissues. Most research groups have developed in-house protocols to perform these studies in a reproducible manner. However, there is a general lack of consistency in how different groups carry out biodistribution experiments. In addition to practical differences that occur during tissue collection (for example, washing and blotting dry the tissue, perfusion, sampling site for a given tissue, etc.), other aspects of biodistribution experiments, which often vary include the methods used for calibrating the injected activity, the processes used to calculate mass normalized tissue uptake (i.e. percentage of injected dose per gram [%ID g^-1] or percentage of injected activity per gram of tissue [%IA g^-1]) values, differences in data processing and statistical analyses (particularly error propagations and calculation of tissue contrast ratios), and variations in how the methods and data are reported and interpreted. This variability hinders the direct comparison of datasets produced at different laboratories. Here, we present a comprehensive guideline for conducting ex vivo biodistribution experiments with radiotracers in rodent models. An open source, freely accessible online biodistribution calculator and associated spreadsheet are provided which can be employed to compute the percent of injected dose per gram of tissue (%ID g^-1), standardized uptake value (SUV by mass), and target-to-background tissue contrast ratios. Finally, advice concerning biodistribution data presentation and statistical analysis are given to help the reader harness the full power of ex vivo biodistribution studies in radiotracer development.

Purpose: Lymph node (LN) excision is critical in oncologic surgery to provide important therapeutic and diagnostic information. LN evaluation helps in staging cancers, predicting prognosis and improving survival. The ultimate wish of a surgical oncologist would be to localize and dissect all pathologically positive LNs while avoiding the morbidity of removing true negative LNs. The goal of our study was to identify a reliable marker for intraoperative molecular imaging of LNs with cancer cells from non-small cell lung cancer versus a LN without.

Procedures: We identified Epithelial Cell Adhesion Molecule (EpCAM), a membrane protein normally expressed in epithelial tissues including lung. We performed immunofluorescence staining on human specimens with a conjugated anti-EpCAM monoclonal antibody.

Results: Fluorescence was significantly higher in LNs with metastases as shown in 48 positive LNs from patients with resected primary lung cancer. There was high fluorescence in both hilar and mediastinal LNs, and in all primary tumor histologies.

Conclusions: EpCAM may be useful for the surgical oncologist for intraoperative molecular imaging of positive LNs from lung cancer.