Correlation between positron emission tomography findings and glucose transporter 1, 3 and L-type amino acid transporter 1 mRNA expression in primary central nervous system lymphomas

18F-FACBC and 18F-FDG PET/MRI in the evaluation of 3 patients with primary central nervous system lymphoma: a pilot study

BACKGROUND

This PET/MRI study compared contrast-enhanced MRI, 18F-FACBC-, and 18F-FDG-PET in the detection of primary central nervous system lymphomas (PCNSL) in patients before and after high-dose methotrexate chemotherapy. Three immunocompetent PCNSL patients with diffuse large B-cell lymphoma received dynamic 18F-FACBC- and 18F-FDG-PET/MRI at baseline and response assessment. Lesion detection was defined by clinical evaluation of contrast enhanced T1 MRI (ce-MRI) and visual PET tracer uptake. SUVs and tumor-to-background ratios (TBRs) (for 18F-FACBC and 18F-FDG) and time-activity curves (for 18F-FACBC) were assessed.

RESULTS

At baseline, seven ce-MRI detected lesions were also detected with 18F-FACBC with high SUVs and TBRs (SUVmax:mean, 4.73, TBRmax: mean, 9.32, SUVpeak: mean, 3.21, TBRpeak:mean: 6.30). High TBR values of 18F-FACBC detected lesions were attributed to low SUVbackground. Baseline 18F-FDG detected six lesions with high SUVs (SUVmax: mean, 13.88). In response scans, two lesions were detected with ce-MRI, while only one was detected with 18F-FACBC. The lesion not detected with 18F-FACBC was a small atypical MRI detected lesion, which may indicate no residual disease, as this patient was still in complete remission 12 months after initial diagnosis. No lesions were detected with 18F-FDG in the response scans.

CONCLUSIONS

18F-FACBC provided high tumor contrast, outperforming 18F-FDG in lesion detection at both baseline and in response assessment. 18F-FACBC may be a useful supplement to ce-MRI in PCNSL detection and response assessment, but further studies are required to validate these findings. Trial registration ClinicalTrials.gov. Registered 15th of June 2017 (Identifier: NCT03188354, https://clinicaltrials.gov/study/NCT03188354 ).

Optimizing Boron Neutron Capture Therapy (BNCT) to Treat Cancer: An Updated Review on the Latest Developments on Boron Compounds and Strategies

Boron neutron capture therapy (BNCT) is a tumor-selective particle radiotherapy. It combines preferential boron accumulation in tumors and neutron irradiation. The recent initiation of BNCT clinical trials employing hospital-based accelerators rather than nuclear reactors as the neutron source will conceivably pave the way for new and more numerous clinical trials, leading up to much-needed randomized trials. In this context, it would be interesting to consider the implementation of new boron compounds and strategies that will significantly optimize BNCT. With this aim in mind, we analyzed, in this review, those articles published between 2020 and 2023 reporting new boron compounds and strategies that were proved therapeutically useful in in vitro and/or in vivo radiobiological studies, a critical step for translation to a clinical setting. We also explored new pathologies that could potentially be treated with BNCT and newly developed theranostic boron agents. All these radiobiological advances intend to solve those limitations and questions that arise during patient treatment in the clinical field, with BNCT and other therapies. In this sense, active communication between clinicians, radiobiologists, and all disciplines will improve BNCT for cancer patients, in a cost- and time-effective way.

Metabolic Reprogramming and Potential Therapeutic Targets in Lymphoma

Lymphoma is a heterogeneous group of diseases that often require their metabolism program to fulfill the demand of cell proliferation. Features of metabolism in lymphoma cells include high glucose uptake, deregulated expression of enzymes related to glycolysis, dual capacity for glycolytic and oxidative metabolism, elevated glutamine metabolism, and fatty acid synthesis. These aberrant metabolic changes lead to tumorigenesis, disease progression, and resistance to lymphoma chemotherapy. This metabolic reprogramming, including glucose, nucleic acid, fatty acid, and amino acid metabolism, is a dynamic process caused not only by genetic and epigenetic changes, but also by changes in the microenvironment affected by viral infections. Notably, some critical metabolic enzymes and metabolites may play vital roles in lymphomagenesis and progression. Recent studies have uncovered that metabolic pathways might have clinical impacts on the diagnosis, characterization, and treatment of lymphoma subtypes. However, determining the clinical relevance of biomarkers and therapeutic targets related to lymphoma metabolism is still challenging. In this review, we systematically summarize current studies on metabolism reprogramming in lymphoma, and we mainly focus on disorders of glucose, amino acids, and lipid metabolisms, as well as dysregulation of molecules in metabolic pathways, oncometabolites, and potential metabolic biomarkers. We then discuss strategies directly or indirectly for those potential therapeutic targets. Finally, we prospect the future directions of lymphoma treatment on metabolic reprogramming.

Efficacy of Boron Neutron Capture Therapy in Primary Central Nervous System Lymphoma: In Vitro and In Vivo Evaluation

Background: Boron neutron capture therapy (BNCT) is a nuclear reaction-based tumor cell-selective particle irradiation method. High-dose methotrexate and whole-brain radiation therapy (WBRT) are the recommended treatments for primary central nervous system lymphoma (PCNSL). This tumor responds well to initial treatment but relapses even after successful treatment, and the prognosis is poor as there is no safe and effective treatment for relapse. In this study, we aimed to conduct basic research to explore the possibility of using BNCT as a treatment for PCNSL. Methods: The boron concentration in human lymphoma cells was measured. Subsequently, neutron irradiation experiments on lymphoma cells were conducted. A mouse central nervous system (CNS) lymphoma model was created to evaluate the biodistribution of boron after the administration of borono-phenylalanine as a capture agent. In the neutron irradiation study of a mouse PCNSL model, the therapeutic effect of BNCT on PCNSL was evaluated in terms of survival. Results: The boron uptake capability of human lymphoma cells was sufficiently high both in vitro and in vivo. In the neutron irradiation study, the BNCT group showed a higher cell killing effect and prolonged survival compared with the control group. Conclusions: A new therapeutic approach for PCNSL is urgently required, and BNCT may be a promising treatment for PCNSL. The results of this study, including those of neutron irradiation, suggest success in the conduct of future clinical trials to explore the possibility of BNCT as a new treatment option for PCNSL.

Positron emission tomography and magnetic resonance imaging in primary central nervous system lymphoma-a narrative review

This review addresses the challenges of primary central nervous system (CNS) lymphoma diagnosis, assessment of treatment response, and detection of recurrence. Primary CNS lymphoma is a rare form of extra-nodal non-Hodgkin lymphoma that can involve brain, spinal cord, leptomeninges, and eyes. Primary CNS lymphoma lesions are most commonly confined to the white matter or deep cerebral structures such as basal ganglia and deep periventricular regions. Contrast-enhanced magnetic resonance imaging (MRI) is the standard diagnostic modality employed by neuro-oncologists. MRI often shows common morphological features such as a single or multiple uniformly well-enhancing lesions without necrosis but with moderate surrounding edema. Other brain tumors or inflammatory processes can show similar radiological patterns, making differential diagnosis difficult. [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) has selected utility in cerebral lymphoma, especially in diagnosis. Primary CNS lymphoma can sometimes present with atypical findings on MRI and FDG PET, such as disseminated disease, non-enhancing or ring-like enhancing lesions. The complementary strengths of PET and MRI have led to the development of combined PET-MR systems, which in some cases may improve lesion characterization and detection. By highlighting active developments in this field, including advanced MRI sequences, novel radiotracers, and potential imaging biomarkers, we aim to spur interest in sophisticated imaging approaches.

High 18F-FDOPA PET Uptake in Primary Central Nervous System Lymphoma

We present a 42-year-old woman with primary central nervous system lymphoma (PCNSL) and strong F-FDOPA PET uptake. F-FDOPA PET has high diagnostic accuracy in gliomas and brain metastases. The L-type amino acid transporter 1, targeted by F-FDOPA and C-MET PET, is a cell-type transporter usually upregulated in malignant tumors, including PCNSL. In this line, strong uptake was already shown with C-MET in PCNSL. We report the same findings with F-FDOPA. Consequently, PCNSL is a possible differential neoplastic diagnosis of F-FDOPA uptake among neoplastic lesions.

Extraprostatic Uptake of 18F-Fluciclovine: Differentiation of Nonprostatic Neoplasms From Metastatic Prostate Cancer

OBJECTIVE. Fluciclovine is a synthetic radiolabeled amino acid analog used for imaging of biochemical recurrent prostate cancer. Uptake of fluciclovine is mediated by several amino acid transporters, including alanine-serine-cysteine transporter 2 and large neutral amino acid transporters, which are known to be overexpressed in other malignancies. CONCLUSION. Knowledge of the common patterns of prostate cancer recurrence, in addition to what other neoplasms can show uptake, is critical for accurate study interpretation.

Positron Emission Tomography-based Analysis Can Accurately Predict Bone Marrow Involvement With Mantle Cell Lymphoma

INTRODUCTION

Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin lymphoma and requires both bone marrow biopsy and fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to correctly stage the disease at diagnosis. However, accurate identification of bone marrow involvement by lymphoma on FDG PET/CT scans has not been previously demonstrated. We hypothesized that a voxel-based analysis of the iliac bones on the FDG PET/CT scan might provide insight into bone marrow involvement.

PATIENTS AND METHODS

A retrospective cohort study of patients with a diagnosis of MCL who had undergone both single iliac bone marrow biopsy and FDG-PET/CT scan from 1 study site were included in the development phase (n = 10). An additional 12 patients from a second institution were included in the validation phase. Using a semiautomated workflow, a voxel-based data set of FDG uptake within the bilateral iliac bones was captured for each patient. In the development phase, empirical receiver operating characteristic curves for each data set were fit. We then identified the standardized uptake value (SUV) threshold cutpoints at which the sensitivity and specificity were optimized to 100%. In the validation phase, we evaluated the performance of these candidate SUV threshold cutpoints in 15 additional patients from a second institution.

RESULTS

We found that 1 cutpoint, > 38% of voxels with activity < 0.95, outperformed all the other candidate cutpoints, correctly classifying all patients except for 1 (overall sensitivity, 100%; specificity, 87.5%).

CONCLUSION

The ability to correctly identify bone marrow involvement using FDG PET/CT-based voxel analysis provides promise as a novel noninvasive method of accurate staging.

Glucose transporters in cancer - from tumor cells to the tumor microenvironment

Solute carriers of the glucose transporter (GLUT) family mediate the first step for cellular glucose usage. The upregulation of GLUTs has been reported in numerous cancer types as a result of perturbation of gene expression or protein relocalization or stabilization. Because they enable to sustain the energy demand required by tumor cells for various biochemical programs, they are promising targets for the development of anticancer strategies. Recently, important biological insights have come from the fine crystal structure determination of several GLUTs; these advances will likely catalyze the development of new selective inhibitory compounds. Furthermore, deregulated glucose metabolism of nontumor cells in the tumor mass is beginning to be appreciated and could have major implications for our understanding of how glucose uptake by specific cell types influences the behavior of neighboring cells in the same microenvironment. In this review, we discuss some of the deregulation mechanisms of glucose transporters, their genetic and pharmacological targeting in cancer, and new functions they may have in nontumor cells of the tumor environment or beyond glucose uptake for glycolysis.

[18F] FDOPA standardized uptake values of brain tumors are not exclusively dependent on LAT1 expression

[18F]-FDOPA is a labeled amino acid (AA) analog used for positron emission tomography (PET) which is gaining increasing interest in the evaluation of brain tumors (BT). The AA-transporter LAT1 has been shown to be involved in [18F]-FDOPA uptake. The aim of this study was to determine whether the [18F]-FDOPA uptake was correlated with level of LAT1 expression in BT. Twenty-eight BT (including 19 gliomas and 9 metastases) were investigated by [18F]-FDOPA-PET prior to surgery and by anti-LAT1 immunohistochemistry on surgical specimens. The quantitative [18F]-FDOPA measured parameters were SUVmax, SUVmean and SUVpeak. LAT1 expression was quantified using a score (0 to 400). A significant [18F]-FDOPA uptake was associated with a LAT1 score ≥ 100 (p = 0.02) but there was no linear correlation between intensity of [18F]-FDOPA uptake and score of LAT1 expression whatever the parameters considered. LAT1 expression alone is not sufficient to explain variation of intensity of [18F]-FDOPA uptake in BT.

Correlation of pretreatment 18F-FDG uptake with clinicopathological factors and prognosis in patients with newly diagnosed diffuse large B-cell lymphoma

Supplemental Digital Content is available in the text.

Objectives

The aim of this study is to determine the correlation of pretreatment fluorine-18 fluorodeoxyglucose uptake with clinicopathological factors and its prognostic value in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL).

Patients and methods

A cohort of 162 patients with newly diagnosed DLBCL who had undergone pretreatment PET/computed tomography was retrospectively reviewed. The relationship of pretreatment maximum standard uptake value (SUV_max) with clinical factors, molecular markers, and efficacy was evaluated. The value of SUV_max in predicting progression-free survival (PFS) and overall survival was analyzed.

Results

In all, 72.9% of the patients received R-CHOP treatment; the rest received CHOP chemotherapy. The median follow-up duration was 30 months (range, 4–124 months). The median SUV_max was 12.2 (range, 1.7–42.7). SUV_max between groups differed significantly with respect to each of International Prognostic Index (IPI) factors, except for age and performance status. High SUV_max was associated with high Ki-67 and Glut-3 protein expression, but not with Glut-1. Complete remission rate differed significantly between the low (SUV_max≤9.0) and the high SUV_max (SUV_max>9.0) groups (91.7 vs. 61.1%, P=0.000). Patients with low SUV_max showed favorable survival (3-year PFS: 92.2 vs. 63.6%, P=0.000; 3-year overall survival: 95.5 vs. 78.3%, P=0.003). On multivariate analyses, SUV_max predicted PFS independent of revised-IPI (SUV_max: P=0.011, hazard ratio 4.784; revised-IPI: P=0.004, hazard ratio 2.551).

Conclusion

Pretreatment SUV_max was associated with clinicopathological factors, efficacy, and survival outcome. A novel prognostic model on the basis of IPI score/pretreatment SUV_max might be useful for risk stratification of patients with newly diagnosed DLBCL Video abstract: http://links.lww.com/NMC/A55.

Dual time-point FDG PET/CT and FDG uptake and related enzymes in lymphadenopathies: preliminary results

PURPOSE

The purpose of this study was to determine the ability of dual time-point (DTP) PET/CT with (18)F-FDG to discriminate between malignant and benign lymphadenopathies. The relationship between DTP FDG uptake and glucose metabolism/hypoxia markers in lymphadenopathies was also assessed.

METHODS

Patients with suspected lymphoma or recently diagnosed treatment-naive lymphoma were prospectively enrolled for DTP FDG PET/CT (scans 60 min and 180 min after FDG administration). FDG-avid nodal lesions were segmented to yield volume and standardized uptake values (SUV), including SUVmax, SUVmean, cSUVmean (with partial volume correction), total lesion glycolysis (TLG) and cTLG (with partial volume correction). Expression of glucose transporter-1 (GLUT-1), hexokinase-II (HK-II), glucose-6-phosphatase (G6Pase) and hypoxia-inducible factor-1alpha (HIF-1alpha) were assessed with immunohistochemistry and enzyme activity was determined for HK and G6Pase.

RESULTS

FDG uptake was assessed in 203 lesions (146 malignant and 57 benign). Besides volume, there were significant increases over time for all parameters, with generally higher levels in the malignant lesions. The retention index (RI) was not able to discriminate between malignant and benign lesions. Volume, SUVmax, TLG and cTLG for both scans were able to discriminate between the two groups statistically, but without complete separation. Glucose metabolism/hypoxia markers were assessed in 15 lesions. TLG and cTLG were correlated with GLUT-1 expression on the 60-min scan. RI-max and RI-mean and SUVmax, SUVmean and cSUVmean on the 60-min scan were significantly correlated with HK-II expression.

CONCLUSION

RI was not able to discriminate between malignant and benign lesions, but some of the SUVs were able to discriminate on the 60-min and 180-min scans. Furthermore, FDG uptake was correlated with GLUT-1 and HK-II expression.