18F-PSMA-1007 PET/CT for response assessment in patients with metastatic renal cell carcinoma undergoing tyrosine kinase or checkpoint inhibitor therapy: preliminary results

Detection of Testicular Metastasis from Renal Cell Carcinoma on PSMA-PET Scan

The use of prostate-specific membrane antigen-positron emission tomography (PSMA-PET) is becoming more widespread for the diagnosis and management of prostate cancer. Here we report a case of oligometastatic renal cell carcinoma (RCC) to the testes diagnosed incidentally on PSMA-PET imaging. This case demonstrates the potential for diagnosis of nonprostate disease with PSMA-PET imaging, as well as the promising nature of PSMA-PET for the diagnosis and surveillance of RCC. In addition, this case report discusses the rare occurrence of oligometastatic RCC to the testis.

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.

68Ga-PSMA-11 PET/CT in Bilateral Clear Cell Renal Cell Carcinoma: an Intra-patient Comparison Between High and Low Grade Tumors

Recent studies have outlined the emerging role of 68Ga-PSMA-11 PET/CT in the diagnostic algorithm of clear cell renal cell carcinoma (ccRCC). We report a unique intra-patient comparison of bilateral primary ccRCC imaged with 68Ga-PSMA-11 PET/CT. Although both tumors resulted 68Ga-PSMA-11 avid, we found a remarkable discrepancy in uptake intensity between the high grade and the low grade ccRCC. This case confirms previous evidence reporting that SUVmax on 68Ga-PSMA-11 PET/CT could be used to discriminate aggressive high grade from more indolent low grade ccRCC, due to their different endothelial expression of PSMA.

Clinical impact of Prostate-Specific Membrane Antigen Positron Emission Tomography (PET) on intensification or deintensification of advanced renal cell carcinoma management

PURPOSE

There is an emerging role of the use of Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography (PET) in renal cell carcinoma. Herein, we report our experience in use of PSMA PET in recurrent or metastatic renal cell carcinoma (RCC).

METHODS

A retrospective analysis of all patients who underwent PSMA PET for suspected recurrent or de-novo metastatic RCC between 2015 and 2020 at three institutions was performed. The primary outcome was change in management (intensification or de-intensification) following PSMA PET scan. Secondary outcomes included histopathological correlation of PSMA avid sites, comparison of sites of disease on PSMA PET to diagnostic CT and time to systemic treatment.

RESULTS

18 F-PSMA-1007 PET/CT in a Case of Von Hippel-Lindau Syndrome

ABSTRACT

We describe 18 F-PSMA-1007 PET/CT findings in case of von Hippel-Lindau syndrome with a cerebellar hemangioblastoma, 6 renal cell carcinomas in the bilateral kidneys, cystic lesions in the pancreas and left adrenal gland, and solid lesions in the bilateral epididymides. 18 F-PSMA-1007 PET/CT showed intense activity with SUV max of 111.3 of the cerebellar hemangioblastoma, variable activity with SUV max range of 6.4-37.6 of the renal cell carcinomas, and increased activity of the bilateral epididymal lesions (SUV max of 5.1 and 8.2 for the left and right epididymal lesions, respectively).

PSMA-Expression Is Highly Associated with Histological Subtypes of Renal Cell Carcinoma: Potential Implications for Theranostic Approaches

In renal cell carcinoma (RCC), accurate imaging methods are required for treatment planning and response assessment to therapy. In addition, there is an urgent need for new therapeutic options, especially in metastatic RCC. One way to combine diagnostics and therapy in a so-called theranostic approach is the use of radioligands directed against surface antigens. For instance, radioligands against prostate-specific membrane antigen (PSMA) have already been successfully used for diagnosis and radionuclide therapy of metastatic prostate cancer. Recent studies have demonstrated that PSMA is expressed not only in prostate cancer but also in the neovasculature of several solid tumors, which has raised hopes to use PSMA-guided theranostic approaches in other tumor entities, too. However, data on PSMA expression in different histopathological subtypes of RCC are sparse. Because a better understanding of PSMA expression in RCC is critical to assess which patients would benefit most from theranostic approaches using PSMA-targeted ligands, we investigated the expression pattern of PSMA in different subtypes of RCC on protein level. Immunohistochemical staining for PSMA was performed on formalin-fixed, paraffin-embedded archival material of major different histological subtypes of RCC (clear cell RCC (ccRCC)), papillary RCC (pRCC) and chromophobe RCC (cpRCC). The extent and intensity of PSMA staining were scored semi-quantitatively and correlated with the histological RCC subtypes. Group comparisons were calculated with the Kruskal-Wallis test. In all cases, immunoreactivity was detected only in the tumor-associated vessels and not in tumor cells. Staining intensity was the strongest in ccRCC, followed by cpRCC and pRCC. ccRCC showed the most diffuse staining pattern, followed by cpRCC and pRCC. Our results provide a rationale for PSMA-targeted theranostic approaches in ccRCC and cpRCC.

Comprehensive Systematic Review of Biomarkers in Metastatic Renal Cell Carcinoma: Predictors, Prognostics, and Therapeutic Monitoring

BACKGROUND

Challenges remain in determining the most effective treatment strategies and identifying patients who would benefit from adjuvant or neoadjuvant therapy in renal cell carcinoma. The objective of this review is to provide a comprehensive overview of biomarkers in metastatic renal cell carcinoma (mRCC) and their utility in prediction of treatment response, prognosis, and therapeutic monitoring in patients receiving systemic therapy for metastatic disease.

METHODS

A systematic literature search was conducted using the PubMed database for relevant studies published between January 2017 and December 2022. The search focused on biomarkers associated with mRCC and their relationship to immune checkpoint inhibitors, targeted therapy, and VEGF inhibitors in the adjuvant, neoadjuvant, and metastatic settings.

RESULTS

The review identified various biomarkers with predictive, prognostic, and therapeutic monitoring potential in mRCC. The review also discussed the challenges associated with anti-angiogenic and immune-checkpoint monotherapy trials and highlighted the need for personalized therapy based on molecular signatures.

CONCLUSION

This comprehensive review provides valuable insights into the landscape of biomarkers in mRCC and their potential applications in prediction of treatment response, prognosis, and therapeutic monitoring. The findings underscore the importance of incorporating biomarker assessment into clinical practice to guide treatment decisions and improve patient outcomes in mRCC.

The Judicious Use of Stereotactic Ablative Radiotherapy in the Primary Management of Localized Renal Cell Carcinoma

Localized renal cell carcinoma is primarily managed surgically, but this disease commonly presents in highly comorbid patients who are poor operative candidates. Less invasive techniques, such as cryoablation and radiofrequency ablation, are effective, but require percutaneous or laparoscopic access, while generally being limited to cT1a tumors without proximity to the renal pelvis or ureter. Active surveillance is another management option for small renal masses, but many patients desire treatment or are poor candidates for active surveillance. For poor surgical candidates, a growing body of evidence supports stereotactic ablative radiotherapy (SABR) as a safe and effective non-invasive treatment modality. For example, a recent multi-institution individual patient data meta-analysis of 190 patients managed with SABR estimated a 5.5% five-year cumulative incidence of local failure with one patient experiencing grade 4 toxicity, and no other grade ≥3 toxic events. Here, we discuss the recent developments in SABR for the management of localized renal cell carcinoma, highlighting key concepts of appropriate patient selection, treatment design, treatment delivery, and response assessment.

Feasibility of biology-guided radiotherapy for metastatic renal cell carcinoma driven by PSMA PET imaging

Background

Biology-guided radiotherapy (BgRT) is a novel treatment where the detection of positron emission originating from a volume called the biological tracking zone (BTZ) initiates dose delivery. Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is a novel imaging technique that may improve patient selection for metastasis-directed therapy in renal cell carcinoma (RCC). This study aims to determine the feasibility of BgRT treatment for RCC.

Material and methods

All consecutive patients that underwent PSMA PET/CT scan for RCC staging at our institution between 2014 and 2020 were retrospectively considered for inclusion. GTVs were contoured on the CT component of the PET/CT scan. The tumor-to-background ratio was quantified from the normalized standardized uptake value (nSUV), defined as the ratio between SUVmax inside the GTV and SUVmean inside the margin expansion. Tumors were classified suitable for BgRT if (1) nSUV was greater or equal to an nSUV threshold and (2) if the BTZ was free of any PET-avid region other than the tumor.

Results

Out of this cohort of 83 patients, 47 had metastatic RCC and were included in this study. In total, 136 tumors were delineated, 1 to 22 tumors per patient, mostly in lung (40%). Using a margin expansion of 5 mm/10 mm/20 mm and nSUV threshold = 3, 66%/63%/41% of tumors were suitable for BgRT treatment. Uptake originating from another tumor, the kidney, or the liver was typically inside the BTZ in tumors judged unsuitable for BgRT.

Conclusions

More than 60% of tumors were found to be suitable for BgRT in this cohort of patients with RCC. However, the proximity of PET-avid organs such as the liver or the kidney may affect BgRT delivery.

Biomarkers for the Detection and Surveillance of Renal Cancer

Renal cell carcinoma (RCC) is a heterogeneous disease characterized by a broad spectrum of disorders in terms of genetics, molecular and clinical characteristics. There is an urgent need for noninvasive tools to stratify and select patients for treatment accurately. In this review, we analyze serum, urinary, and imaging biomarkers that have the potential to detect malignant tumors in patients with RCC. We discuss the characteristics of these numerous biomarkers and their ability to be used routinely in clinical practice. The development of biomarkers continues to evolve with promising prospects.

18 F-Choline Versus 68 Ga-PSMA-11 PET/CT Imaging Comparison in Incidental Clear Cell Renal Cell Carcinoma

ABSTRACT

Few articles in literature describe the potential usefulness of 18 F-choline PET/CT and particularly 68 Ga-PSMA-11 PET/CT in imaging of clear cell renal cell carcinoma (ccRCC). We report a unique comparison in literature between the 2 radiotracers in a patient who underwent left nephrectomy with diagnosis of ccRCC, grade 3. 68 Ga-PSMA-11 PET/CT confirmed its emerging role in imaging ccRCC, as the incidentally detected renal neoplasm showed a significant higher uptake in comparison to 18 F-choline PET/CT, inducing surgical indication.

Adjuvant Therapy for High-Risk Localized Renal Cell Carcinoma: Current Landscape and Future Direction

Locally and regionally advanced renal cell carcinoma (RCC) can recur at high rates even after visually complete resection of primary disease. Both targeted therapies and immunotherapies represent potential agents that might help reduce recurrence of RCC in these patients. This paper reviews the current body of evidence defining their potential impact and examines the large Phase III randomized clinical trials that have been performed to assess the safety and efficacy of these systemic therapies in the adjuvant setting. Given that the findings from these trials have been predominantly negative, this paper also explores the role of other potential adjuvant agents, including single and combination agent targeted therapies and immunotherapies, whose use is currently limited to metastatic RCC. Finally, the use of radiation therapy and the use of advanced imaging modalities in RCC are also considered.

Advances in Imaging-Based Biomarkers in Renal Cell Carcinoma: A Critical Analysis of the Current Literature

Cross-sectional imaging is the standard diagnostic tool to determine underlying biology in renal masses, which is crucial for subsequent treatment. Currently, standard CT imaging is limited in its ability to differentiate benign from malignant disease. Therefore, various modalities have been investigated to identify imaging-based parameters to improve the noninvasive diagnosis of renal masses and renal cell carcinoma (RCC) subtypes. MRI was reported to predict grading of RCC and to identify RCC subtypes, and has been shown in a small cohort to predict the response to targeted therapy. Dynamic imaging is promising for the staging and diagnosis of RCC. PET/CT radiotracers, such as ¹⁸F-fluorodeoxyglucose (FDG), ¹²⁴I-cG250, radiolabeled prostate-specific membrane antigen (PSMA), and ¹¹C-acetate, have been reported to improve the identification of histology, grading, detection of metastasis, and assessment of response to systemic therapy, and to predict oncological outcomes. Moreover, ⁹⁹Tc-sestamibi and SPECT scans have shown promising results in distinguishing low-grade RCC from benign lesions. Radiomics has been used to further characterize renal masses based on semantic and textural analyses. In preliminary studies, integrated machine learning algorithms using radiomics proved to be more accurate in distinguishing benign from malignant renal masses compared to radiologists' interpretations. Radiomics and radiogenomics are used to complement risk classification models to predict oncological outcomes. Imaging-based biomarkers hold strong potential in RCC, but require standardization and external validation before integration into clinical routines.

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.

Impact of Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography in the Management of Oligometastatic Renal Cell Carcinoma

Background

Prostate-specific membrane antigen (PSMA) is overexpressed in the neovasculature of renal cell carcinoma (RCC). However, there remains limited evidence regarding the use of PSMA positron emission tomography/computed tomography (PET/CT) in RCC.

Objective

To assess the impact of PSMA PET/CT in the management of metastatic RCC.

Design, setting, and participants

This was a retrospective review of patients who underwent PSMA PET/CT from 2014 to 2020 for restaging or suspected metastatic RCC in a tertiary academic setting.

Outcome measurements and statistical analysis

Management plans before and after PSMA PET/CT were recorded. Impact was classified as high (change of treatment intent, modality, or site), medium (change in treatment method), or low. Secondary outcomes included the patient-level detection rate, PSMA PET/CT parameters, sensitivity, and comparison to CT and, if available, fluorodeoxyglucose (FDG) PET/CT.

Results and limitations

Sixty-one patients met the inclusion criteria, of whom 54 (89%) had clear cell RCC. PSMA-positive disease was detected in 51 patients (84%). For 30 patients (49%) there was a change in management due to PSMA PET/CT (high impact, 29 patients, 48%). In 15 patients (25%), more metastases were detected on PSMA PET/CT than on CT. The sensitivity of combined PSMA PET/CT and diagnostic CT was 91% (95% confidence interval 77–98%). In a subcohort of 40 patients, the detection rate was 88% for PSMA and 75% for FDG PET/CT (p = 0.17). The maximum standardised uptake value (SUV_max) was higher for PSMA than for FDG PET/CT (15.2 vs 8.0; p = 0.02). Limitations include selection bias due to the retrospective design, and a lack of corresponding histopathology for all patients.

Conclusions

PSMA PET/CT is a promising imaging modality in metastatic RCC and led to a change in management in 49% of patients. PSMA PET/CT detected additional metastases compared to CT in 25% of patients and registered a significantly higher SUV_max than FDG PET/CT. Prospective studies are required to further define its role.

Patient summary

We report on a group of patients undergoing a new type of imaging for suspected advanced kidney cancer, called PSMA PET/CT. This imaging changed the management plan in 49% of the patients. PSMA PET/CT detected metastases in 84% of our patients and detected more metastases than computed tomography imaging in 25%.

PSMA Radioligand Uptake as a Biomarker of Neoangiogenesis in Solid Tumours: Diagnostic or Theragnostic Factor?

Due to its overexpression on the surface of prostate cancer cells, prostate-specific membrane antigen (PSMA) is a relatively novel effective target for molecular imaging and radioligand therapy (RLT) in prostate cancer. Recent studies reported that PSMA is expressed in the neovasculature of various types of cancer and regulates tumour cell invasion as well as tumour angiogenesis. Several authors explored the role of diagnostic and therapeutic PSMA radioligands in various malignancies. In this narrative review, we describe the current status of the literature on PSMA radioligands' application in solid tumours other than prostate cancer to explore their potential role as diagnostic or therapeutic agents, with particular regard to the relevance of PSMA radioligand uptake as neoangiogenetic biomarker. Hence, a comprehensive review of the literature was performed to find relevant articles on the applications of PSMA radioligands in non-prostate solid tumours. Data on the general, methodological and clinical aspects of all included studies were collected. Forty full-text papers were selected for final review, 8 of which explored PSMA radioligand PET/CT performances in gliomas, 3 in salivary gland malignancies, 6 in thyroid cancer, 2 in breast cancer, 16 in renal cell carcinoma and 5 in hepatocellular carcinoma. In the included studies, PSMA radioligand PET showed promising performance in patients with non-prostate solid tumours. Further studies are needed to better define its potential role in oncological patients management, especially in those undergoing antineoangiogenic therapies, and to assess the efficacy of PSMA-RLT in this clinical context.

Molecular Imaging of Renal Cell Carcinoma in Precision Medicine

Renal cell carcinoma (RCC) is the sixth most common cancer among men and the ninth among women, and its prognosis is closely correlated with metastasis. Targeted therapy and immunotherapy are the main adjuvant treatments for advanced RCC and require early diagnosis, precise assessment, and prediction of the therapeutic responses. Current conventional imaging methods of RCC only provide structural information rather than biological processes. Noninvasive diagnostic tools are therefore needed to image RCC early and accurately at the molecular level. Nuclear medicine imaging combines the high sensitivity of radionuclides with the high resolution of structural imaging to visualize the metabolic processes and specific targets of RCC for more accurate and reliable diagnosis, staging, prognosis prediction, and response assessment. This review summarizes the most recent applications of nuclear medicine receptor imaging and metabolic imaging in RCC and highlights future development perspectives in the field.

Novel Imaging Methods for Renal Mass Characterization: A Collaborative Review

CONTEXT

The incidental detection of localized renal masses has been rising steadily, but a significant proportion of these tumors are benign or indolent and, in most cases, do not require treatment. At the present time, a majority of patients with an incidentally detected renal tumor undergo treatment for the presumption of cancer, leading to a significant number of unnecessary surgical interventions that can result in complications including loss of renal function. Thus, there exists a clinical need for improved tools to aid in the pretreatment characterization of renal tumors to inform patient management.

OBJECTIVE

To systematically review the evidence on noninvasive, imaging-based tools for solid renal mass characterization.

EVIDENCE ACQUISITION

The MEDLINE database was systematically searched for relevant studies on novel imaging techniques and interpretative tools for the characterization of solid renal masses, published in the past 10 yr.

EVIDENCE SYNTHESIS

Over the past decade, several novel imaging tools have offered promise for the improved characterization of indeterminate renal masses. Technologies of particular note include multiparametric magnetic resonance imaging of the kidney, molecular imaging with targeted radiopharmaceutical agents, and use of radiomics as well as artificial intelligence to enhance the interpretation of imaging studies. Among these, 99mTc-sestamibi single photon emission computed tomography/computed tomography (CT) for the identification of benign renal oncocytomas and hybrid oncocytic chromophobe tumors, and positron emission tomography/CT imaging with radiolabeled girentuximab for the identification of clear cell renal cell carcinoma, are likely to be closest to implementation in clinical practice.

CONCLUSIONS

A number of novel imaging tools stand poised to aid in the noninvasive characterization of indeterminate renal masses. In the future, these tools may aid in patient management by providing a comprehensive virtual biopsy, complete with information on tumor histology, underlying molecular abnormalities, and ultimately disease prognosis.

PATIENT SUMMARY

Not all renal tumors require treatment, as a significant proportion are either benign or have limited metastatic potential. Several innovative imaging tools have shown promise for their ability to improve the characterization of renal tumors and provide guidance in terms of patient management.

68Ga-PSMA-11 PET/CT Parameter Correlates with Pathological VEGFR-2/PDGFR-β Expression in Renal Cell Carcinoma Patients

BACKGROUND

Response prediction is necessary for renal cell carcinoma (RCC) tumors. We aim to evaluate parameters derived from ⁶⁸ Ga-PSMA-11 PET/CT images for prediction of pathological VEGFR-2/PDGFR-β expression of primary RCC tumors.

METHODS

Forty-eight RCC patients were retrospectively enrolled with preoperative ⁶⁸ Ga-PSMA-11 PET/CT scan and surgical specimen. Radiological parameters including tumor diameter, mean CT value, and maximal standard uptake value (SUV_max) were derived from PET/CT images and pathological VEGFR-2/PDGFR-β/PSMA expression were identified with immunohistochemistry. Mann-Whitney U test was performed for continuous variables and the chi-square test for categorical variables. ROC was used for determining the effectiveness of preoperative parameters in differentiating VEGFR-2/PDGFR-β expression. Univariate and multivariate logistic regression analyses were performed for significant parameters to predict VEGFR-2 & PDGFR-β co-expression.

RESULTS

Of the 48 tumors, 25 (52.1%) harbored positive VEGFR-2 expression, 28 (58.3%) harbored positive PDGFR-β expression, and 24 (50%) were both VEGFR-2 positive and PDGFR-β positive. SUV_max significantly differed by subgroups of VEGFR-2/PDGFR-β expression (both P < 0.001). SUV_max demonstrated superior performance for differentiating VEGFR-2 & PDGFR-β co-expression (positive vs. negative), with area under the curve 0.87 (95% CI 0.78-0.96, P < 0.001), sensitivity 93% and specificity 78%. Moreover, SUV_max was identified as the significant predictor for VEGFR-2 & PDGFR-β co-expression (odds ratio 4.01, 95% CI 1.99-8.08, P < 0.001). Concordant with radiological findings with ⁶⁸ Ga-PSMA-11 PET/CT, pathological PSMA staining intensity was significantly higher in both VEGFR-2-positive tumor and PDGFR-β-positive tumor (P = 0.009 and P < 0.001, respectively).

CONCLUSION

⁶⁸ Ga-PSMA-11 PET/CT could effectively identify pathological VEGFR-2/PDGFR-β expression of primary RCC tumors, which may help with selection of mRCC patients suitable for TKIs treatment.

[68Ga]Ga-PSMA-11 PET/CT has potential application in predicting tumor HIF-2α expression and therapeutic response to HIF-2α antagonists in patients with RCC

OBJECTIVE

To evaluate the efficacy of parameters derived from [⁶⁸Ga]Ga-PSMA-11 PET/CT images in predicting pathological HIF-2α expression in primary tumors among patients with renal cell carcinoma (RCC).

METHODS

Fifty-three RCC patients with preoperative [⁶⁸Ga]Ga-PSMA-11 PET/CT scans and complete surgical specimens were retrospectively enrolled in this study. Radiographic parameters were obtained from PET/CT images, and immunohistochemistry was used to measure the expression of HIF-2α and PSMA. Continuous variables and categorical variables were analyzed by the Mann-Whitney U test and chi-square test, respectively. ROC analysis was used to test the efficacy of several preoperative parameters in identifying pathological HIF-2α expression. Univariable logistic regression analyses were performed for significant parameters to predict pathological HIF-2α expression in RCC.

RESULTS

Of the 53 tumors, 29 (54.7%) had high expression of HIF-2α. The SUV_max was significantly different in the HIF-2α expression subgroups (p < 0.001). SUV_max emerged as the most significant parameter to differentiate HIF-2α expression subgroups (high vs. low), with the AUC of 0.93 (95% CI 0.85-1.00, p < 0.001), sensitivity of 90%, and specificity of 88%. Furthermore, SUV_max was confirmed as the most significant predictor of HIF-2α expression level by univariable logistic regression model analysis (odds ratio 1.39, 95% CI 1.17-1.65, p < 0.001). Consistent with the radiographic results of [⁶⁸Ga]Ga-PSMA-11 PET/CT, the staining intensity of pathological PSMA was significantly higher in HIF-2α-high-expressing tumors (p = 0.003).

CONCLUSIONS

[⁶⁸Ga]Ga-PSMA-11 PET/CT was superior in identifying pathological HIF-2α expression in primary tumors of RCC patients, demonstrating its potential application in predicting responses to HIF-2α antagonists.

KEY POINTS

• [⁶⁸Ga]Ga-PSMA-11 PET/CT could potentially predict the HIF-2α expression of primary tumors among patients with RCC. • SUV_maxof [⁶⁸Ga]Ga-PSMA-11 PET/CT was the most significant predictor of HIF-2α expression level. • This probability could help predict the therapeutic response of patients with RCC to HIF-2α antagonists.

PSMA PET/CT in Renal Cell Carcinoma: An Overview of Current Literature

Although the vast majority of prostate-specific membrane antigen (PSMA) positron emission tomography (PET) imaging occurs in the field of prostate cancer, PSMA is also highly expressed on the cell surface of the microvasculature of several other solid tumors, including renal cell carcinoma (RCC). This makes it a potentially interesting imaging target for the staging and monitoring of RCC. The objective of this review is to provide an overview of the current evidence regarding the use of PSMA PET/Computed Tomography in RCC patients.

Application of 18F Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography in Monitoring Gastric Metastasis and Cancer Thrombi from Renal Cell Carcinoma

Background. Renal cell carcinoma (RCC) with gastric metastasis is rare, particularly accompanied by multiple cancer thrombi. Methods. We reported a 66-year-old man with a history of a right radical nephrectomy because of RCC. The patient underwent 18F prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) scanning after 6 months of targeted therapy because of gastric metastasis and cancer thrombi. We conducted a systematic review of the literature and identified 73 cases of RCC with gastric metastasis. We analyzed the clinicopathological characteristics, therapies, and outcomes of patients. Results. 18F-PSMA PET/CT showed a large mass in the gastric fundus and cancer thrombi in the right atrium, inferior vena cava, and splenic vein with intense tracer uptake. Other metastases with increased tracer uptake included multiple bones and abdominal lymph nodes. The majority of gastric metastasis of RCC were men (53/73, 72.6%), with a median age at presentation of 67 (from 48 to 87) years. Gastric metastasis of RCC was mainly metachronous, and presented with small polyps or mass appearance and often accompanied by multiple-site metastases and gastrointestinal symptoms. An overall median interval between nephrectomy and diagnosis of gastric metastasis was 6 (from 0.1 to 23) years, and an overall median survival time was 14 (from 0.25 to 72) months. The median interval time of solitary gastric metastasis was longer than gastric metastasis with multiple-site metastases (7 vs.5 years; $P=0.034$ ). Patients with gastric and multiple-site metastases had higher mortality than patients with solitary metastasis (17 vs.1; $P=0.028$ ). The patients with synchronous gastric metastasis had a shorter survival time than metachronous gastric metastasis (6 vs.17 months; $P=0.018$ ). Conclusions. Postoperative follow-up of multiple imaging modalities to monitor recurrence and metastasis is necessary and important. PSMA PET/CT can improve the detection sensitivity of RCC, especially in metastatic clear cell renal cell carcinoma (ccRCC), and could provide a basis for disease staging, restaging, and therapeutic efficacy evaluation.

Theranostics in oncology: What radiologists want to know

Combination of radioligand imaging and therapy, so called radiotheranostics, is a novel tool of precision oncology with proven clinical value. In-depth knowledge of functional imaging nuances is critically needed for precise prognostication and guidance of management. Here, we review theranostic applications with up to Phase III type evidence for outcome improvement: Imaging and therapy of neuroendocrine neoplasms (NEN) exploiting high levels of somatostatin receptor (SSTR) expression and radiotheranostics of prostate cancer targeting the prostate specific membrane antigen (PSMA). This narrative review focusses on these two applications and elucidates patient selection and response assessment by radioligand scintigraphy and/or positron emission tomography. Furthermore, we provide a brief outlook on future applications for novel targets outside of NEN and prostate cancer.

Immature Plasma Cell Myeloma Mimics Metastatic Renal Cell Carcinoma on 18F-PSMA-1007 PET/CT Due to Endothelial PSMA-Expression

We present a 71-year-old female patient who underwent 18F-PSMA-1007 PET/CT for suspected metastatic renal cell carcinoma (RCC), as RCC also shows high PSMA-expression in tumor neovascularization. 18F-PSMA-1007 PET/CT showed a high PSMA-avidity in the renal tumor, enlarged intra-abdominal and mediastinal lymph nodes. Moreover, PSMA-positive pleural, pulmonal and osseous lesions were found. However, histopathology revealed an immature plasma cell myeloma with an endothelial PSMA-expression of the neovasculature. This case illustrates the increased PSMA-avidity in multiple myeloma and highlights PSMA as a potential theragnostic target in multiple myeloma. For clinical routine, lymphatic diseases such as extramedullary myeloma should be considered as differential diagnosis in PSMA-avid renal masses on PET/CT.