Fructose 1,6-Bisphosphatase 1 Expression Reduces 18F-FDG Uptake in Clear Cell Renal Cell Carcinoma

Theranostics in Renal Cell Carcinoma-A Step Towards New Opportunities or a Dead End-A Systematic Review

Background: Renal cell carcinoma is one of the most aggressive urogenital malignancies, with an increasing number of cases worldwide. The majority of cases are diagnosed at an advanced stage, as this form of growth is typically silent. An accurate evaluation of the extent of the disease is crucial for selecting the most appropriate treatment approach. Nuclear medicine imaging is increasingly being applied in oncological diagnostics, prompting ongoing research into renal cell carcinoma markers that could serve as a foundation for theranostic approaches in this disease. Positron emission tomography/computed tomography imaging with prostate-specific membrane antigen (PSMA) ligands has already demonstrated successful utility in diagnosis of other cancers, including prostate cancer and gliomas. Emerging evidence of high sensitivity and specificity in detecting renal cell carcinoma lesions provides a suitable foundation for its application in both the diagnosis and subsequent management of this malignancy. Methods: This systematic review synthesizes the current scientific evidence on the molecular imaging of renal cell carcinoma using PSMA ligands, emphasizing the potential future applications of this imaging marker in theranostic approaches. Results and Conclusions: Based on a systematic review of the literature, it appears that PET/CT with PSMA ligands has the potential to surpass traditional imaging techniques in diagnostic accuracy while also providing valuable prognostic information.

The evolution of PET imaging in renal, bladder, upper urinary tract urothelial, testicular and penile carcinoma - Today's impact, tomorrow's potential

INTRODUCTION

The advancement of hybrid PET/CT or PET/MRI imaging for non-prostate genitourinary cancers has not experienced the rapid progress of prostate cancer. Nevertheless, these neoplasms are aggressive and reliable imaging plays a pivotal role in enhancing patients' quality of life and prognosis.

AREAS COVERED

the main evidence regarding [18F]FDG and non-[18F]FDG PET/CT or PET/MRI in non-prostate uro-oncological malignancies are summarized and discussed. Moreover, potential future directions concerning PET imaging in these neoplasms are debated, with the aim to stimulate future research projects covering these fields.

EXPERT OPINION

In Renal Cell Carcinoma (RCC), [18F]FDG PET/CT demonstrates varying efficacy in staging, restaging, and prognostic stratification, but PSMA PET/CT is emerging as a potential game-changer, particularly in advanced, high-grade aggressive clear cell RCC. [18F]FDG PET/CT may see an increased use in N and M-staging of bladder cancer, as well as for detecting recurrence and response to neoadjuvant chemotherapy. Preliminary data regarding [68Ga]-FAPI also looks promising in this context. [18F]FDG PET/MRI could be useful for the T-staging of bladder cancer, while upper tract urothelial carcinoma still lacks of molecular imaging literature reports. In testicular and penile cancer [18F]FDG PET/CT has demonstrated its usefulness in several clinical settings, although experiences with non-[18F]FDG radiotracers are lacking.

Expression of fructose-1,6-bisphosphatase 1 is associated with [18F]FDG uptake and prognosis in patients with mesial temporal lobe epilepsy

OBJECTIVES

To determine whether fructose-1,6-bisphosphatase 1 (FBP1) expression is associated with [¹⁸F]FDG PET uptake and postsurgical outcomes in patients with mesial temporal lobe epilepsy (mTLE) and to investigate whether the molecular mechanism involving gamma-aminobutyric acid type A receptor (GABA_AR), glucose transporter-3 (GLUT-3), and hexokinase-II (HK-II).

METHODS

Forty-three patients with mTLE underwent [¹⁸F]FDG PET/CT. Patients were divided into Ia (Engel class Ia) and non-Ia (Engel class Ib-IV) groups according to more than 1 year of follow-up after surgery. The maximum standard uptake value (SUV_max) and asymmetry index (AI) of hippocampus were measured. The relationship among the SUV_max, AI, prognosis, and FBP1 expression was analyzed. A lithium-pilocarpine acute mTLE rat model was subjected to [¹⁸F]FDG micro-PET/CT. Hippocampal SUV_max and FBP1, GABA_AR, GLUT-3, and HK-II expression were analyzed.

RESULTS

SUV_max was higher in the Ia group than in the non-Ia group (7.31 ± 0.97 vs. 6.56 ± 0.96, p < 0.05) and FBP1 expression was lower in the Ia group (0.24 ± 0.03 vs. 0.27 ± 0.03, p < 0.01). FBP1 expression was negatively associated with SUV_max and AI (p < 0.01). In mTLE rats, the hippocampal FBP1 increased (0.26 ± 0.00 vs. 0.17 ± 0.00, p < 0.0001), and SUV_max, GLUT-3 and GABA_AR levels decreased significantly (0.73 ± 0.12 vs. 1.46 ± 0.23, 0.20 ± 0.01 vs. 0.32 ± 0.05, 0.26 ± 0.02 vs. 0.35 ± 0.02, p < 0.05); no significant difference in HK-II levels was observed. In mTLE patients and rats, FBP1 negatively correlated with SUV_max and GLUT-3 and GABA_AR levels (p < 0.05).

CONCLUSION

FBP1 expression was inversely associated with SUV_max in mTLE, which might inhibit [¹⁸F]FDG uptake by regulating GLUT-3 expression. High FBP1 expression was indicative of low GABA_AR expression and poor prognosis.

KEY POINTS

• It is of paramount importance to explore the deep pathophysiological mechanisms underlying the pathogenesis of mesial temporal lobe epilepsy and find potential therapeutic targets. • [¹⁸F]FDG PET has demonstrated low metabolism in epileptic regions during the interictal period, and hypometabolism may be associated with prognosis, but the pathomechanism of this association remains uncertain. • Our results support the possibility that FBP1 might be simultaneously involved in the regulation of glucose metabolism levels and the excitability of neurons and suggest that targeting FBP1 may be a viable strategy in the diagnosis and treatment of mesial temporal lobe epilepsy.

The Emerging Role of PET/CT with PSMA-Targeting Radiopharmaceuticals in Clear Cell Renal Cancer: An Updated Systematic Review

BACKGROUND

Recent articles proposed the employment of positron emission tomography/computed tomography (PET/CT) with prostate-specific membrane antigen (PSMA)-targeting radiopharmaceuticals in clear cell renal cell carcinoma (ccRCC).

METHODS

The authors performed a comprehensive literature search of studies on the performance of PET/CT with PSMA-targeting radiopharmaceuticals in ccRCC. Original articles concerning this imaging examination were included in newly diagnosed ccRCC patients and ccRCC patients with disease recurrence.

RESULTS

A total of sixteen papers concerning the diagnostic performance of PSMA-targeted PET/CT in ccRCC (331 patients) were included in this systematic review. The included articles demonstrated an excellent detection rate of PSMA-targeting PET/CT in ccRCC.

CONCLUSIONS

PSMA-targeted PET/CT seems promising in detecting ccRCC lesions as well as in discriminating the presence of aggressive phenotypes. Prospective multicentric studies are warranted to strengthen the role of PSMA-targeting PET/CT in ccRCC.

Efficacy of Pre-operative 18F-FDG PET/CT in Prognostic Prediction in Patients With Renal Cell Carcinoma

BACKGROUND/AIM

This study analyzed the parameters provided by preoperative ¹⁸ F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for prognostic prediction of renal cell carcinoma (RCC).

PATIENTS AND METHODS

FDG-PET/CT data from 66 clear cell RCC and 19 non-clear cell RCC cases between January 2015 and October 2018 were reviewed retrospectively. We compared the two groups according to recurrence/metastasis to determine prognosis-influencing factors. Multivariate Cox hazard regression models were constructed to evaluate factors potentially predicting disease-free survival (DFS) after adjustment for confounders. DFS was then compared between groups.

RESULTS

Standardized uptake values (SUV) of the PET/CT scan were independent predictors of prognosis after adjusting for confounders. RCC cases were divided into two groups by optimal cut-off values. Differences between DFS percentages in high and low SUV groups were significant. Similar results were obtained in clear cell RCC groups.

CONCLUSION

Increased SUV of the PET/CT scan are significant predictors of worse prognoses in patients with surgically resected RCC.

Role of PSMA-ligands imaging in Renal Cell Carcinoma management: current status and future perspectives

Background

Renal masses detection is continually increasing worldwide, with Renal Cell Carcinoma (RCC) accounting for approximately 90% of all renal cancers and remaining one of the most aggressive urological malignancies. Despite improvements in cancer management, accurate diagnosis and treatment strategy of RCC by computed tomography (CT) and magnetic resonance imaging (MRI) are still challenging. Prostate-Specific Membrane Antigen (PSMA) is known to be highly expressed on the endothelial cells of the neovasculature of several solid tumors other than prostate cancer, including RCC. In this context, recent preliminary studies reported a promising role for positron emission tomography (PET)/CT with radiolabeled molecules targeting PSMA, in alternative to fluorodeoxyglucose (FDG) in RCC patients.

Purpose

The aim of our review is to provide an updated overview of current evidences and major limitations regarding the use of PSMA PET/CT in RCC.

Methods

A literature search, up to 31 December 2021, was performed using the following electronic databases: PubMed, SCOPUS, Web of Science, and Google Scholar.

Results

The findings of this review suggest that PSMA PET/CT could represent a valid imaging option for diagnosis, staging, and therapy response evaluation in RCC, particularly in clear cell RCC.

Conclusions

Further studies are needed for this “relatively” new imaging modality to consolidate its indications, timing, and practical procedures.

Metabolic tumour volume on 18F-FDG PET/CT predicts extended pathological T stages in patients with renal cell carcinoma at staging

We evaluated the predictive value of ¹⁸F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/CT (PET/CT) for extended pathological T (pT) stages (≥ pT3a) in Renal cell carcinoma (RCC) patients at staging. Thirty-eight RCC patients who underwent ¹⁸F-FDG PET/CT at staging, followed by radical nephrectomy between September 2016 and September 2018, were included in this prospective study. Patients were classified into two groups (limited pT stage: stage T1/2, n = 17; extended pT stage: T3/4, n = 21). Univariate and multivariate logistic regression analyses were performed to identify clinicopathological and metabolic variables to predict extended pT stages. ¹⁸F-FDG metabolic parameters were compared in relation to International Society of Urological Pathology (ISUP) grade and lymphovascular invasion (LVI). In univariate analysis, maximum standardised uptake value, metabolic tumour volume (MTV), and ISUP grade were significant. In multivariate analysis, MTV was the only significant factor of extended pT stages. With a cut-off MTV of 21.2, an area under the curve was 0.944, which was higher than 0.824 for clinical T stages (p = 0.037). In addition, high MTV, but not tumour size, was significantly correlated with aggressive pathologic features (ISUP grade and LVI). High glycolytic tumour volume on ¹⁸F-FDG PET/CT in RCC patients at staging is predictive of extended pT stages which could aid decision-making regarding the best type of surgery.

Renal Cell Carcinoma: the Oncologist Asks, Can PSMA PET/CT Answer?

PURPOSE OF REVIEW

To critically review the potential clinical applications of prostate-specific membrane antigen (PSMA) radioactive ligands in renal cell carcinoma (RCC).

RECENT FINDINGS

Radioactive probes targeting PSMA hold promise in several malignancies in addition to prostate cancer, owing to the expression of PSMA by tumor neovasculature. The majority of clear cell RCCs (ccRCC), the most malignant RCC subtype, express PSMA on tumor-associated neovasculature. The endothelium of less aggressive RCC subtypes is PSMA positive in a lower, but still significant percentage of cases. PSMA might therefore represent an interesting theragnostic target in RCC. The preliminary data available suggest a potential role for PSMA-targeting radiopharmaceuticals in complementing conventional imaging for staging ccRCC patients at risk of nodal involvement and oligometastatic disease. Additional applications of PSMA imaging may be the selection and the response assessment of patients receiving anti-angiogenic treatments. The effectiveness of PSMA-targeting radionuclide therapy should also be investigated.