SIGNALING PATHWAYS THAT DRIVE 18F-FDG ACCUMULATION IN CANCER

Synthesis and preclinical evaluation of 68Ga-labeled PSMA tracers with improved pharmacological properties

Prostate cancer (PCa) is one of the most common tumors in men, with the overexpression of prostate-specific membrane. In this study, we developed four new 68Ga-labeled PSMA-targeting tracers by introducing quinoline, phenylalanine and decanoic acid groups to enhance their lipophilicity, strategically limiting their metabolic pathway through the urinary system. Four radiotracers were synthesized with radiochemical purity >95 %, and exhibited high stability in vivo and in vitro. The inhibition constants (Ki) of SDTWS01-04 to PSMA were in the nanomolar range (<10 nM). Micro PET/CT imaging and biodistribution analysis revealed that 68Ga-SDTWS01 enabled clear tumor visualization in PET images at 1.5 h post-injection, with excellent pharmacokinetic properties. Notably, the kidney uptake of 68Ga-SDTWS01 significantly reduced, with higher tumor-to-kidney ratio (0.36 ± 0.02), tumor-to-muscle ratio (24.31 ± 2.10), compared with 68Ga-PSMA-11 (T/K: 0.15 ± 0.01; T/M: 14.97 ± 1.40), suggesting that 68Ga-SDTWS01 is a promising radiotracer for the diagnosis of PCa. Moreover, SDTWS01 with a chelator DOTA could also label 177Lu and 225Ac, which could be used for the treatment of PCa.

Performance of fibroblast activating protein inhibitor PET imaging for pancreatic neoplasms assessment: a systematic review and meta-analysis

BACKGROUND

Recent studies have shown the potential of fibroblast activating protein inhibitor (FAPI) PET imaging for pancreatic cancer assessment.

PURPOSE

This article is dedicated to comparing the diagnostic efficacy of FAPI PET and [18F]fluorodeoxyglucose (FDG) PET in the evaluation of primary tumors, lymph nodes, and distant metastases in pancreatic cancer.

METHODS

In this review, we conducted a systematic search of studies published in PubMed and Web of Science databases up to September 18, 2023. All included studies used radionuclide labeled FAPI and FDG as PET diagnostic tracers to evaluate their applicability in patients with pancreatic cancer.

RESULTS

The FAPI PET imaging group showed significantly higher sensitivity in the detection of primary lesions (1.000, [95% CI: 0.999-1.000]), lymph node metastases (0.624 [95% CI: 0.391-0.834]) and distant metastatic (0.965 [95% CI: 0.804-1.000]) in pancreatic cancer compared to the FDG PET imaging group (0.889 [95% CI: 0.788-0.966], 0.373 [95% CI: 0.163-0.606] and 0.889 [95% CI: 0.689-0.999], respectively). Furthermore, the maximum standardized uptake value (SUVmax) in FAPI PET imaging is significantly higher than that in FDG imaging for primary lesions (mean difference (MD) = 7.51, 95% CI: 5.34-9.67).

CONCLUSION

Compared with [18F]FDG PET/CT, FAPI PET imaging showed higher sensitivity, SUVmax. This method can be effectively utilized for the evaluation of pancreatic cancer.

CLINICAL RELEVANCE STATEMENT

Fibroblast activating protein inhibitor PET may be a better alternative to [18F]FDG in evaluating primary pancreatic cancer, lymph node metastases, and distant metastases.

KEY POINTS

Fibroblast activating protein inhibitor (FAPI) PET is compared with FDG PET for evaluating pancreatic cancer. Multiple radiolabeled FAPI variants have shown promising results in the diagnosis of pancreatic cancer. FAPI PET imaging effectively helps clinicians diagnose and stage pancreatic cancer.

ImmunoPET imaging of Trop2 in patients with solid tumours

Accurately predicting and selecting patients who can benefit from targeted or immunotherapy is crucial for precision therapy. Trophoblast cell surface antigen 2 (Trop2) has been extensively investigated as a pan-cancer biomarker expressed in various tumours and plays a crucial role in tumorigenesis through multiple signalling pathways. Our laboratory successfully developed two 68Ga-labelled nanobody tracers that can rapidly and specifically target Trop2. Of the two tracers, [68Ga]Ga-NOTA-T4, demonstrated excellent pharmacokinetics in preclinical mouse models and a beagle dog. Moreover, [68Ga]Ga-NOTA-T4 immuno-positron emission tomography (immunoPET) allowed noninvasive visualisation of Trop2 heterogeneous and differential expression in preclinical solid tumour models and ten patients with solid tumours. [68Ga]Ga-NOTA-T4 immunoPET could facilitate clinical decision-making through patient stratification and response monitoring during Trop2-targeted therapies.

Molecular Imaging of Steroid Receptors in Breast Cancer

ABSTRACT

Steroid receptors regulate gene expression for many important physiologic functions and pathologic processes. Receptors for estrogen, progesterone, and androgen have been extensively studied in breast cancer, and their expression provides prognostic information as well as targets for therapy. Noninvasive imaging utilizing positron emission tomography and radiolabeled ligands targeting these receptors can provide valuable insight into predicting treatment efficacy, staging whole-body disease burden, and identifying heterogeneity in receptor expression across different metastatic sites. This review provides an overview of steroid receptor imaging with a focus on breast cancer and radioligands for estrogen, progesterone, and androgen receptors.

In-vivo correlations of fluorescent or radioisotope glucose-analogs in imaging cancer metabolism

OBJECTIVE

To investigate the impact of different tracer modifications on the imaging of cancer metabolism, focusing on the comparison of fluorescent glucose-analog tracers (2-NBDG and 2-DG-750) and the radiolabeled tracer 18F-FDG in both in-vitro and in-vivo settings.

METHODS

We conducted an in-vitro comparative study using four cancer cell lines, each with unique glucose uptake characteristics. The study involved direct comparison of three tracers: 2-NBDG, 2-DG-750 and 18F-FDG, examining their internalization behaviors, metabolic functionality and localization effects in cancer metabolism imaging.

RESULTS

The study revealed that each tracer exhibits distinct internalization behaviors correlated with imaging label size and type. 18F-FDG showed the highest uptake efficiency. Fluorescent molecules were found to accumulate in tumors primarily due to hydrophobic interactions and possible aggregation, indicating inefficiency in metabolism and suitability for imaging metabolic phenomena when compared to radiolabeled biomolecules.

CONCLUSION

Our findings demonstrate that despite certain impracticalities, nuclear imaging, particularly using radiolabeled biomolecules like 18F-FDG, offers significant potential for accurately capturing biological phenomena. This is crucial for future advancements in both clinical and research settings. The study emphasizes the limitations of fluorescent molecules in imaging metabolic activities due to their inefficient metabolism and aggregation tendencies.

Development of an Engineered Single-Domain Antibody for Targeting MET in Non-Small Cell Lung Cancer

The Mesenchymal Epithelial Transition (MET) receptor tyrosine kinase is upregulated or mutated in 5% of non-small-cell lung cancer (NSCLC) patients and overexpressed in multiple other cancers. We sought to develop a novel single-domain camelid antibody with high affinity for MET that could be used to deliver conjugated payloads to MET expressing cancers. From a naïve camelid variable-heavy-heavy (VHH) domain phage display library, we identified a VHH clone termed 1E7 that displayed high affinity for human MET and was cross-reactive with MET across multiple species. When expressed as a bivalent human Fc fusion protein, 1E7-Fc was found to selectively bind to EBC-1 (MET amplified) and UW-Lung 21 (MET exon 14 mutated) cell lines by flow cytometry and immunofluorescence imaging. Next, we investigated the ability of [89Zr]Zr-1E7-Fc to detect MET expression in vivo by PET/CT imaging. [89Zr]Zr-1E7-Fc demonstrated rapid localization and high tumor uptake in both xenografts with a %ID/g of 6.4 and 5.8 for EBC-1 and UW-Lung 21 at 24 h, respectively. At the 24 h time point, clearance from secondary and nontarget tissues was also observed. Altogether, our data suggest that 1E7-Fc represents a platform technology that can be employed to potentially both image and treat MET-altered NSCLC.

Predicting programmed death-ligand 1 (PD-L1) expression with fluorine-18 fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) metabolic parameters in resectable non-small cell lung cancer

BACKGROUND

Programmed death-ligand 1 (PD-L1) expression is a predictive biomarker for immunotherapy in non-small cell lung cancer (NSCLC). PD-L1 and glucose transporter 1 expression are closely associated, and studies demonstrate correlation of PD-L1 with glucose metabolism.

AIM

The aim of this study was to investigate the association of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) metabolic parameters with PD-L1 expression in primary lung tumour and lymph node metastases in resected NSCLC.

METHODS

We conducted a retrospective analysis of 210 patients with node-positive resectable stage IIB-IIIB NSCLC. PD-L1 tumour proportion score (TPS) was determined using the DAKO 22C3 immunohistochemical assay. Semi-automated techniques were used to analyse pre-operative [18F]FDG-PET/CT images to determine primary and nodal metabolic parameter scores (including max, mean, peak and peak adjusted for lean body mass standardised uptake values (SUV), metabolic tumour volume (MTV), total lesional glycolysis (TLG) and SUV heterogeneity index (HISUV)).

RESULTS

Patients were predominantly male (57%), median age 70 years with non-squamous NSCLC (68%). A majority had negative primary tumour PD-L1 (TPS < 1%; 53%). Mean SUVmax, SUVmean, SUVpeak and SULpeak values were significantly higher (p < 0.05) in those with TPS ≥ 1% in primary tumour (n = 210) or lymph nodes (n = 91). However, ROC analysis demonstrated only moderate separability at the 1% PD-L1 TPS threshold (AUCs 0.58-0.73). There was no association of MTV, TLG and HISUV with PD-L1 TPS.

CONCLUSION

This study demonstrated the association of SUV-based [18F]FDG-PET/CT metabolic parameters with PD-L1 expression in primary tumour or lymph node metastasis in resectable NSCLC, but with poor sensitivity and specificity for predicting PD-L1 positivity ≥ 1%.

CLINICAL RELEVANCE STATEMENT

Whilst SUV-based fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography metabolic parameters may not predict programmed death-ligand 1 positivity ≥ 1% in the primary tumour and lymph nodes of resectable non-small cell lung cancer independently, there is a clear association which warrants further investigation in prospective studies.

TRIAL REGISTRATION

Non-applicable KEY POINTS: • Programmed death-ligand 1 immunohistochemistry has a predictive role in non-small cell lung cancer immunotherapy; however, it is both heterogenous and dynamic. • SUV-based fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) metabolic parameters were significantly higher in primary tumour or lymph node metastases with positive programmed death-ligand 1 expression. • These SUV-based parameters could potentially play an additive role along with other multi-modal biomarkers in selecting patients within a predictive nomogram.

PTPRH promotes the progression of non-small cell lung cancer via glycolysis mediated by the PI3K/AKT/mTOR signaling pathway

BACKGROUND

The protein tyrosine phosphatase H receptor (PTPRH) is known to regulate the occurrence and development of pancreatic and colorectal cancer. However, its association with glycolysis in non-small cell lung cancer (NSCLC) is still unclear. In this study, we aimed to investigate the relationship between PTPRH expression and glucose metabolism and the underlying mechanism of action.

METHODS

The expression of PTPRH in NSCLC cells was evaluated by IHC staining, qRT‒PCR and Western blotting. The effect of PTPRH on cell biological behavior was evaluated by colony assays, EdU experiments, Transwell assays, wound healing assays and flow cytometry. Changes in F-18-fluorodeoxyglucose (18F-FDG) uptake and glucose metabolite levels after altering PTPRH expression were detected via a gamma counter and lactic acid tests. The expression of glycolysis-related proteins in NSCLC cells was detected by Western blotting after altering PTPRH expression.

RESULTS

The results showed that PTPRH was highly expressed in clinical patient tissue samples and closely related to tumor diameter and clinical stage. In addition, PTPRH expression was associated with glycometabolism indexes on 18F-FDG positron emission tomography/computed tomography (PET/CT) imaging, the expression level of Ki67 and the expression levels of glycolysis-related proteins. PTPRH altered cell behavior, inhibited apoptosis, and promoted 18F-FDG uptake, lactate production, and the expression of glycolysis-related proteins. In addition, PTPRH modulated the glycometabolism of NSCLC cells via the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway, as assessed using LY294002 and 740Y-P (an inhibitor and agonist of PI3K, respectively). The same results were validated in vivo using a xenograft tumor model in nude mice. Protein expression levels of PTPRH, glycolysis-related proteins, p-PI3K/PI3K and p-AKT/AKT were measured by IHC staining using a subcutaneous xenograft model in nude mice.

CONCLUSIONS

In summary, we report that PTPRH promotes glycolysis, proliferation, migration, and invasion via the PI3K/AKT/mTOR signaling pathway in NSCLC and ultimately promotes tumor progression, which can be regulated by LY294002 and 740Y-P. These results suggest that PTPRH is a potential therapeutic target for NSCLC.

Exploring the efficacy of 18F-FDG PET/CT in hepatocellular carcinoma diagnosis: role of Ki-67 index and tumor differentiation

PURPOSE

The sensitivity of [18F] fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) for detecting hepatocellular carcinoma (HCC) has not been clarified thoroughly. Our study seeks to explore the association between the Ki-67 index and FDG-avidity in HCC tumors using 18F-FDG PET/CT.

METHODS

112 HCC lesions from 109 patients detected by 18F-FDG PET/CT were included retrospectively between August 2017 and May 2022, comprising 82 lesions in the training cohort and 30 in the validation cohort to simulate prospective studies. In the training cohort, lesions were stratified by a lesion-to-liver maximum standardized uptake value (SUVmax) ratio cut-off of 1.59. The relationships between lesion-to-liver SUVmax ratios and several clinical factors including tumor differentiation, alpha fetoprotein (AFP), carcinoembryonic antigen (CEA), hepatitis B virus (HBV) infection, Ki-67 index et al. were assessed. These findings were subsequently validated in the independent validation cohort.

RESULTS

In the training cohort, group A1 lesions demonstrated a higher Ki-67 index (%, 40.00 [30.00, 57.50] vs. 10.00 [5.00, 28.75], p<0.001) than group A0, the positive correlation between FDG-avidity and Ki-67 index was revealed by multivariate analysis, OR=1.040, 95% CI of OR [1.004-1.077], p=0.030. The calculated cut-off value was 17.5% using the receiver operating characteristic (ROC) curve, with an area under curve (AUC) of 0.834 and 95% CI [0.742-0.926], p<0.001. These findings were further validated in the independent validation cohort, with similar results (AUC=0.875, 95% CI [0.750-1.000], p<0.001).

CONCLUSION

In comparison to tumor differentiation, Ki-67 index demonstrates a stronger association with FDG-avidity in HCC tumors, and when the Ki-67 index exceeds 17.5%, 18F-FDG PET/CT might serve as a useful indicator for HCC.

Preclinical Imaging of Prostate Cancer

Prostate cancer remains a major cause of mortality and morbidity, affecting millions of men, with a large percentage expected to develop the disease as they reach advanced ages. Treatment and management advances have been dramatic over the past 50 years or so, and one aspect of these improvements is reflected in the multiple advances in diagnostic imaging techniques. Much attention has been focused on molecular imaging techniques that offer high sensitivity and specificity and can now more accurately assess disease status and detect recurrence earlier. During development of molecular imaging probes, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) must be evaluated in preclinical models of the disease. If such agents are to be translated to the clinic, where patients undergoing these imaging modalities are injected with a molecular imaging probe, these agents must first be approved by the FDA and other regulatory agencies prior to their adoption in clinical practice. Scientists have worked assiduously to develop preclinical models of prostate cancer that are relevant to the human disease to enable testing of these probes and related targeted drugs. Challenges in developing reproducible and robust models of human disease in animals are beset with practical issues such as the lack of natural occurrence of prostate cancer in mature male animals, the difficulty of initiating disease in immune-competent animals and the sheer size differences between humans and conveniently smaller animals such as rodents. Thus, compromises in what is ideal and what can be achieved have had to be made. The workhorse of preclinical animal models has been, and remains, the investigation of human xenograft tumor models in athymic immunocompromised mice. Later models have used other immunocompromised models as they have been found and developed, including the use of directly derived patient tumor tissues, completely immunocompromised mice, orthotopic methods for inducing prostate cancer within the mouse prostate itself and metastatic models of advanced disease. These models have been developed in close parallel with advances in imaging agent chemistries, radionuclide developments, computer electronics advances, radiometric dosimetry, biotechnologies, organoid technologies, advances in in vitro diagnostics, and overall deeper understandings of disease initiation, development, immunology, and genetics. The combination of molecular models of prostatic disease with radiometric-based studies in small animals will always remain spatially limited due to the inherent resolution sensitivity limits of PET and SPECT decay processes, fundamentally set at around a 0.5 cm resolution limit. Nevertheless, it is central to researcher's efforts and to successful clinical translation that the best animal models are adopted, accepted, and scientifically verified as part of this truly interdisciplinary approach to addressing this important disease.

Early Reduction of Glucose Consumption Is a Biomarker of Kinase Inhibitor Efficacy Which Can Be Reversed with GLUT1 Overexpression in Lung Cancer Cells

PURPOSE

Small molecule inhibitors that target oncogenic driver kinases are an important class of therapies for non-small cell lung cancer (NSCLC) and other malignancies. However, these therapies are not without their challenges. Each inhibitor works on only a subset of patients, the pharmacokinetics of these inhibitors is variable, and these inhibitors are associated with significant side effects. Many of these inhibitors lack non-invasive biomarkers to confirm pharmacodynamic efficacy, and our understanding of how these inhibitors block cancer cell growth remains incomplete. Limited clinical studies suggest that early (< 2 weeks after start of therapy) changes in tumor glucose consumption, measured by [18F]FDG PET imaging, can predict therapeutic efficacy, but the scope of this strategy and functional relevance of this inhibition of glucose consumption remains understudied. Here we demonstrate that early inhibition of glucose consumption as can be measured clinically with [18F]FDG PET is a consistent phenotype of efficacious targeted kinase inhibitors and is necessary for the subsequent inhibition of growth across models of NSCLC.

METHODS

We tested nine NSCLC cell lines (A549, H1129, H1734, H1993, H2228, H3122, H460, HCC827, and PC9 cells) and ten targeted therapies (afatinib, buparlisib, ceritinib, cabozantinib, crizotinib, dovitinib, erlotinib, ponatinib, trametinib, and vemurafenib) across concentrations ranging from 1.6 nM to 5 µM to evaluate whether these inhibitors block glucose consumption at 24-h post-drug treatment and cell growth at 72-h post-drug treatment. We overexpressed the facilitative glucose transporter SLC2A1 (GLUT1) to test the functional connection between blocked glucose consumption and cell growth after treatment with a kinase inhibitor. A subset of these inhibitors and cell lines were studied in vivo.

RESULTS

Across the nine NSCLC cell lines, ten targeted therapies, and a range of inhibitor concentrations, whether a kinase inhibitor blocked glucose consumption at 24-h post-drug treatment strongly correlated with whether that inhibitor blocked cell growth at 72-h post-drug treatment in cell culture. These results were confirmed in vivo with [18F]FDG PET imaging. GLUT1 overexpression blocked the kinase inhibitors from limiting glucose consumption and cell growth.

CONCLUSIONS

Our results demonstrate that the early inhibition of lung cancer glucose consumption in response to a kinase inhibitor is a strong biomarker of and is often required for the subsequent inhibition of cell growth. Early inhibition of glucose consumption may provide complementary information to other biomarkers in determining whether a drug will effectively limit tumor growth.

Pancreatic cancer epigenetics: adaptive metabolism reprograms starving primary tumors for widespread metastatic outgrowth

Pancreatic cancer is a paradigm for adaptation to extreme stress. That is because genetic drivers are selected during tissue injury with epigenetic imprints encoding wound healing responses. Ironically, epigenetic memories of trauma that facilitate neoplasia can also recreate past stresses to restrain malignant progression through symbiotic tumor:stroma crosstalk. This is best exemplified by positive feedback between neoplastic chromatin outputs and fibroinflammatory stromal cues that encase malignant glands within a nutrient-deprived desmoplastic stroma. Because epigenetic imprints are chemically encoded by nutrient-derived metabolites bonded to chromatin, primary tumor metabolism adapts to preserve malignant epigenetic fidelity during starvation. Despite these adaptations, stromal stresses inevitably awaken primordial drives to seek more hospitable climates. The invasive migrations that ensue facilitate entry into the metastatic cascade. Metastatic routes present nutrient-replete reservoirs that accelerate malignant progression through adaptive metaboloepigenetics. This is best exemplified by positive feedback between biosynthetic enzymes and nutrient transporters that saturate malignant chromatin with pro-metastatic metabolite byproducts. Here we present a contemporary view of pancreatic cancer epigenetics: selection of neoplastic chromatin under fibroinflammatory pressures, preservation of malignant chromatin during starvation stresses, and saturation of metastatic chromatin by nutritional excesses that fuel lethal metastasis.

Clinical prospective study of Gallium 68 (68Ga)-labeled fibroblast-activation protein inhibitor PET/CT in the diagnosis of biliary tract carcinoma

PURPOSE

This study is to investigate the [68Ga]Ga-DOTA-FAPI PET/CT diagnosis performance in biliary tract carcinoma (BTC) and analyze the association between [68Ga]Ga-DOTA-FAPI PET/CT and clinical indexes.

METHODS

A prospective study (NCT05264688) was performed between January 2022 and July 2022. Fifty participants were scanned using [68Ga]Ga-DOTA-FAPI and [18F]FDG PET/CT and acquired pathological tissue. We employed the Wilcoxon signed-rank test to compare the uptake of [68Ga]Ga-DOTA-FAPI and [18F]FDG, and the McNemar test was used to compare the diagnostic efficacy between the two tracers. Spearman or Pearson correlation was used to assess the association between [68 Ga]Ga-DOTA-FAPI PET/CT and clinical indexes.

RESULTS

In total, 47 participants (mean age 59.09 ± 10.98 [range 33-80 years]) were evaluated. The [68Ga]Ga-DOTA-FAPI detection rate was greater than [18F]FDG in primary tumors (97.62% vs. 85.71%), nodal metastases (90.05% vs. 87.06%), and distant metastases (100% vs. 83.67%). The uptake of [68Ga]Ga-DOTA-FAPI was higher than [18F]FDG in primary lesions (intrahepatic cholangiocarcinoma, 18.95 ± 7.47 vs. 11.86 ± 0.70, p = 0.001; extrahepatic cholangiocarcinoma, 14.57 ± 6.16 vs. 8.80 ± 4.74, p = 0.004), abdomen and pelvic cavity nodal metastases (6.91 ± 6.56 vs. 3.94 ± 2.83, p < 0.001), and distant metastases (pleural, peritoneum, omentum, and mesentery, 6.37 ± 4.21 vs. 4.50 ± 1.96, p = 0.01; bone, 12.15 ± 6.43 vs. 7.51 ± 4.54, p = 0.008). There was a significant correlation between [68Ga]Ga-DOTA-FAPI uptake and fibroblast-activation protein (FAP) expression (Spearman r = 0.432, p = 0.009), carcinoembryonic antigen (CEA) (Pearson r = 0.364, p = 0.012), and platelet (PLT) (Pearson r = 0.35, p = 0.016). Meanwhile, a significant relationship between [68Ga]Ga-DOTA-FAPI metabolic tumor volume and carbohydrate antigen199 (CA199) (Pearson r = 0.436, p = 0.002) was confirmed.

CONCLUSION

[68Ga]Ga-DOTA-FAPI had a higher uptake and sensitivity than [18F]FDG in the diagnosis of BTC primary and metastatic lesions. The correlation between [68Ga]Ga-DOTA-FAPI PET/CT indexes and FAP expression, CEA, PLT, and CA199 were confirmed.

TRIAL REGISTRATION

clinicaltrials.gov: NCT 05,264,688.

Pacritinib inhibits glucose consumption in squamous cell lung cancer cells by targeting FLT3

Squamous cell lung cancer maintains its growth through elevated glucose consumption, but selective glucose consumption inhibitors are lacking. Here, we discovered using a high-throughput screen new compounds that block glucose consumption in three squamous cell lung cancer cell lines and identified 79 compounds that block glucose consumption in one or more of these cell lines. Based on its ability to block glucose consumption in all three cell lines, pacritinib, an inhibitor of FMS Related Receptor Tyrosine Kinase 3 (FLT3) and Janus Kinase 2 (JAK2), was further studied. Pacritinib decreased glucose consumption in squamous cell lung cancer cells in cell culture and in vivo without affecting glucose consumption in healthy tissues. Pacritinib blocked hexokinase activity, and Hexokinase 1 and 2 mRNA and protein expression. Overexpression of Hexokinase 1 blocked the ability of pacritinib to inhibit glucose consumption in squamous cell lung cancer cells. Overexpression of FLT3 but not JAK2 significantly increased glucose consumption and blocked the ability of pacritinib to inhibit glucose consumption in squamous cell lung cancer cells. Additional FLT3 inhibitors blocked glucose consumption in squamous cell lung cancer cells. Our study identifies FLT3 inhibitors as a new class of inhibitors that can block glucose consumption in squamous cell lung cancer.

[68Ga]Ga-FAPI-04 PET MRI/CT in the evaluation of gastric carcinomas compared with [18F]-FDG PET MRI/CT: a meta-analysis

OBJECTIVES

To compare the detection rates of [⁶⁸Ga]Ga-FAPI-04 PET MRI/CT vs. [¹⁸F]-FDG PET MRI/CT in gastric cancer.

METHODS

An extensive librarian-led literature search of PubMed, Embase, Web of Science, the Cochrane Central Library, and ClinicalTrials.gov was performed. The primary outcomes were sensitivity in patient-based evaluations, detection of lymph node metastases, and peritoneal involvement.

RESULTS

Five studies, including 148 participants, were analyzed. [⁶⁸Ga]Ga-FAPI-04 PET MRI/CT has a comparatively high sensitivity in patient-based evaluations compared with [¹⁸F]-FDG PET MRI/CT (risk difference = 0.16, 95% CI 0.09-0.22, P < 0.00001). The [⁶⁸Ga]Ga-FAPI-04 PET MRI/CT group has a comparatively higher sensitivity in detecting lymph node metastases (RR = 0.15, 95% CI 0.01-0.29, P = 0.04), peritoneal involvement (RR = 0.55, 95% CI 0.38-0.72, P < 0.00001) in gastric cancer than [¹⁸F]-FDG PET MRI/CT group.

CONCLUSIONS

This systematic review confirmed the advantage of [⁶⁸Ga]Ga-FAPI-04 PET MRI/CT in gastric cancer. [⁶⁸Ga]Ga-FAPI-04 PET MRI/CT was superior to [¹⁸F]-FDG PET MRI/CT in detecting the primary tumor, lymph node metastases, and peritoneal metastases. More studies are needed for the sensitivity and specificity of [⁶⁸Ga]Ga-FAPI-04 PET MRI/CT in different pathological types of gastric cancer.

Progesterone Receptor-Mediated Regulation of Cellular Glucose and 18F-Fluorodeoxyglucose Uptake in Breast Cancer

Context

Positron emission tomography imaging with 2-deoxy-2-[¹⁸F]-fluoro-D-glucose (FDG) is used clinically for initial staging, restaging, and assessing therapy response in breast cancer. Tumor FDG uptake in steroid hormone receptor-positive breast cancer and physiologic FDG uptake in normal breast tissue can be affected by hormonal factors such as menstrual cycle phase, menopausal status, and hormone replacement therapy.

Objective

The purpose of this study was to determine the role of the progesterone receptor (PR) in regulating glucose and FDG uptake in breast cancer cells.

Methods and Results

PR-positive T47D breast cancer cells treated with PR agonists had increased FDG uptake compared with ethanol control. There was no significant change in FDG uptake in response to PR agonists in PR-negative MDA-MB-231 cells, MDA-MB-468 cells, or T47D PR knockout cells. Treatment of T47D cells with PR antagonists inhibited the effect of R5020 on FDG uptake. Using T47D cell lines that only express either the PR-A or the PR-B isoform, PR agonists increased FDG uptake in both cell types. Experiments using actinomycin D and cycloheximide demonstrated the requirement for both transcription and translation in PR regulation of FDG uptake. GLUT1 and PFKFB3 mRNA expression and the enzymatic activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were increased after progestin treatment of T47D cells.

Conclusion

Thus, progesterone and progestins increase FDG uptake in T47D breast cancer cells through the classical action of PR as a ligand-activated transcription factor. Ligand-activated PR ultimately increases expression and activity of proteins involved in glucose uptake, glycolysis, and the pentose phosphate pathway.