Targeting Chemokine Receptor CXCR4 and Translocator Protein for Characterization of High-Risk Plaque in Carotid Stenosis Ex Vivo

Grosse GM, Bascuñana P, Schulz-Schaeffer WJ, Teebken OE, Wilhelmi M, Worthmann H, Ross TL, Wester HJ, Kropf S, Derlin T, Bengel FM, Bankstahl JP, Weissenborn K

12.07.2018 [Original Artikel]

BACKGROUND AND PURPOSE: This pilot study aims to demonstrate the feasibility of targeting molecular characteristics of high-risk atherosclerotic plaque in symptomatic and asymptomatic carotid stenosis (CS), that is, upregulation of the translocator protein (TSPO) and the chemokine receptor type 4 (CXCR4), by means of molecular imaging. METHODS: In a translational setting, specimens of carotid plaques of patients with symptomatic and asymptomatic CS obtained by carotid endarterectomy were analyzed for the presence of TSPO and CXCR4 by autoradiography, using the positron emission tomography tracers 18F-GE180 and 68Ga-Pentixafor and evaluated by histopathology. In addition, 68Ga-Pentixafor positron emission tomography/computed tomography was performed in a patient with high-grade CS. RESULTS: Distinct patterns of upregulation of TSPO (18F-GE180 uptake) and CXCR4 (68Ga-Pentixafor uptake) were identified in carotid plaque by autoradiography. The spatial distribution was associated with specific histological hallmarks that are established features of high-risk plaque: TSPO upregulation correlated with activated macrophages infiltration, whereas CXCR4 upregulation also corresponded to areas of intraplaque hemorrhage. 68Ga-Pentixafor uptake was significantly higher in plaques of symptomatic compared with asymptomatic CS. Clinical positron emission tomography revealed marked 68Ga-Pentixafor uptake in carotid plaque of a patient with high-grade CS. CONCLUSIONS: Clinical imaging of molecular signatures of high-risk atherosclerotic plaque is feasible and may become a promising diagnostic tool for comprehensive characterization of carotid disease. This methodology provides a platform for future studies targeting carotid plaque.

Imaging of chemokine receptor CXCR4 expression in culprit and nonculprit coronary atherosclerotic plaque using motion-corrected [68Ga]pentixafor PET/CT

Derlin T, Sedding DG, Dutzmann J, Haghikia A, König T, Napp LC, Schütze C, Owsianski-Hille N, Wester HJ, Kropf S, Thackeray JT, Bankstahl JP, Geworski L, Ross TL, Bauersachs J, Bengel FM

03.07.2018 [Original Artikel]

PURPOSE: The chemokine receptor CXCR4 is a promising target for molecular imaging of CXCR4+ cell types, e.g. inflammatory cells, in cardiovascular diseases. We speculated that a specific CXCR4 ligand, [68Ga]pentixafor, along with novel techniques for motion correction, would facilitate the in vivo characterization of CXCR4 expression in small culprit and nonculprit coronary atherosclerotic lesions after acute myocardial infarction by motion-corrected targeted PET/CT. METHODS: CXCR4 expression was analysed ex vivo in separately obtained arterial wall specimens. [68Ga]Pentixafor PET/CT was performed in 37 patients after stent-based reperfusion for a first acute ST-segment elevation myocardial infarction. List-mode PET data were reconstructed to five different datasets using cardiac and/or respiratory gating. Guided by CT for localization, the PET signals of culprit and various groups of nonculprit coronary lesions were analysed and compared. RESULTS: Ex vivo, CXCR4 was upregulated in atherosclerotic lesions, and mainly colocalized with CD68+ inflammatory cells. In vivo, elevated CXCR4 expression was detected in culprit and nonculprit lesions, and the strongest CXCR4 PET signal (median SUVmax 1.96; interquartile range, IQR, 1.55-2.31) was observed in culprit coronary artery lesions. Stented nonculprit lesions (median SUVmax 1.45, IQR 1.23-1.88; P = 0.048) and hot spots in naive remote coronary segments (median SUVmax 1.34, IQR 1.23-1.74; P = 0.0005) showed significantly lower levels of CXCR4 expression. Dual cardiac/respiratory gating provided the strongest CXCR4 PET signal and the highest lesion detectability. CONCLUSION: We demonstrated the basic feasibility of motion-corrected targeted PET/CT imaging of CXCR4 expression in coronary artery lesions, which was triggered by vessel wall inflammation but also by stent-induced injury. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of coronary atherosclerotic plaque.

Anti-Inflammatory Effects on Atherosclerotic Lesions Induced by CXCR4-Directed Endoradiotherapy

Li X, Kemmer L, Zhang X, Kircher M, Buck AK, Wester HJ, Hacker M, Lapa C

03.07.2018 [Original Artikel]

[68Ga]Ga-Pentixafor PET/MRI for CXCR4 Imaging of Chronic Lymphocytic Leukemia: Preliminary Results

Mayerhoefer ME, Jaeger U, Staber P, Raderer M, Wadsak W, Pfaff S, Kornauth C, Senn D, Weber M, Wester HJ, Skrabs C, Haug A

01.07.2018 [Original Artikel]

OBJECTIVES: This prospective proof-of-principle study aimed to determine whether [Ga]Ga-Pentixafor uptake, which reflects CXCR4 expression, is higher in the bone marrow of chronic lymphocytic leukemia (CLL) than in other oncological diseases without bone marrow infiltration and can therefore be used for CLL imaging. MATERIALS AND METHODS: Thirteen CLL patients and 20 controls (10 with pancreatic adenocarcinoma and 10 with mucosa-associated lymphoid tissue lymphoma) with histologically proven cancer underwent [Ga]Ga-Pentixafor positron emission tomography/magnetic resonance imaging. Standardized [Ga]Ga-Pentixafor uptake values (SUVmax, SUVmean) were measured in the bone marrow of the pelvis, the lumbar vertebra L4, and the bony structure with the visually highest tracer uptake ("hottest lesion"). Mean apparent diffusion coefficient values were also measured in the pelvis. Serum leukocyte count (gram per liter), lymphocyte percentage (percent), lactate dehydrogenase (unit per liter), β2-microglobulin (milligram per deciliter), and C-reactive protein (milligram per deciliter) were measured. Statistical analyses comprised analysis of variance with Games-Howell post hoc tests and Spearman correlation coefficients. RESULTS: SUVmax and SUVmean differed significantly between CLL and pancreatic adenocarcinoma in the pelvis (P = 0.032 and P = 0.008) and lumbar vertebra L4 (both P < 0.001). SUVmean also differed in the pelvis (P = 0.020) and L4 (P = 0.041), and SUVmax in L4 (P = 0.019), between CLL and mucosa-associated lymphoid tissue lymphoma. Receiver operating characteristic-based areas under the curve for separation of CLL from the control groups were greatest for the SUVmax of the bony structure with the strongest [Ga]Ga-Pentixafor uptake (0.94) and the SUVmax of L4 (0.92). There was no significant correlation between [Ga]Ga-Pentixafor uptake and pelvic apparent diffusion coefficients or serum parameters. CONCLUSIONS: [Ga]Ga-Pentixafor positron emission tomography/magnetic resonance imaging may possibly be useful for CXCR4-based CLL imaging.

Feasibility of CXCR4-directed radioligand therapy in advanced diffuse large B cell lymphoma

Lapa C, Hänscheid H, Kircher M, Schirbel A, Wunderlich G, Werner R, Samnick S, Kotzerke J, Einsele H, Buck A, Wester HJ, Grigoleit GU

18.05.2018 [Original Artikel]

We have recently reported on our experience with C-X-C-motif chemokine receptor 4- (CXCR4-) directed radioligand therapy (RLT) in multiple myeloma and acute leukemia. Methods: Six patients with heavily pre-treated relapsed diffuse large B cell lymphoma (DLBCL) (3 males, 3 females; aged, 54±8 years) underwent CXCR4-directed RLT in combination with conditioning chemotherapy and allogeneic stem cell transplantation (SCT). In 2 patients, radioimmunotherapy (RIT) targeting CD20 or CD66 was added to enhance anti-lymphoma activity. Endpoints were incidence and severity of adverse events, progression-free and overall survival. Results: RLT as well as additional RIT were well-tolerated without any acute adverse events or changes in vital signs. Successful engraftment was recorded after a median of 11 days (range, 9-13 d). In the 4 patients who were available for follow-up (one patient died of CNS aspergillosis 29 days, another of sepsis in aplasia 34 days after after RLT), CXCR4-directed RLT resulted in partial response in 2/4 cases (both treated with additional RIT) and mixed response in the remaining 2 subjects. Response duration was rather short-lived with median progression-free survival of 62 days (range, 29-110 d) and median overall survival of 76 days (range, 29-313 d). Conclusion: CXCR4-directed RLT (in combination with additional RIT) as a conditioning regimen prior to allogeneic SCT in DLBCL is feasible.

Isolated metastasis of an EGFR-L858R-mutated NSCLC of the meninges: the potential impact of CXCL12/CXCR4 axis in EGFRmut NSCLC in diagnosis, follow-up and treatment

Lüke F, Blazquez R, Yamaci RF, Lu X, Pregler B, Hannus S, Menhart K, Hellwig D, Wester HJ, Kropf S, Heudobler D, Grosse J, Moosbauer J, Hutterer M, Hau P, Riemenschneider MJ, Bayerlová M, Bleckmann A, Polzer B, Beißbarth T, Klein CA, Pukrop T

10.04.2018 [Original Artikel]

Brain and leptomeningeal metastasis (LMM) of non-small cell lung cancer is still associated with poor prognosis. Moreover, the current diagnostic standard for LMM often yields false negative results and the scientific progress in this field is still unsatisfying. We present a case of a 71-year old patient with an isolated LMM. While standard diagnostics could only diagnose a cancer of unknown primary, the use of [68Ga]-Pentixafor-PET/CT (CXCR4-PET/CT, a radiotracer targeting CXCR4) and a liquid biopsy of the cerebrospinal fluid revealed the primary NSCLC. The detection of L858R-EGFR, a common driver mutation in NSCLC, enabled us to treat the patient with Afatinib and monitor treatment using [68Ga]-Pentixafor PET/CT. To estimate the impact of CXCR4 signaling and its ligands in NSCLC brain metastasis we looked at their expression and correlation with EGFR mutations in a primary and brain metastasis data set and investigated the previously described binding of extracellular ubiquitin to CXCR4. In conclusion, we describe a novel approach to improve diagnostics towards LMM and underline the impact of the CXCL12/CXCR4 axis in brain metastasis in a subset of NSCLC patients. We cannot confirm a correlation of CXCR4 expression with EGFR mutations or the binding of extracellular ubiquitin as previously reported.

[68Ga]Pentixafor-PET/MRI for the detection of Chemokine receptor 4 expression in atherosclerotic plaques

Li X, Heber D, Leike T, Beitzke D, Lu X, Zhang X, Wei Y, Mitterhauser M, Wadsak W, Kropf S, Wester HJ, Loewe C, Hacker M, Haug AR

01.04.2018 [Original Artikel]

PURPOSE: The expression of chemokine receptor type 4 (CXCR4) was found co-localized with macrophages on the atherosclerotic vessel wall and participated in the initial emigration of leukocytes. Gallium-68 [68Ga]Pentixafor has recently been introduced for the imaging of atherosclerosis by targeting CXCR4. We sought to evaluate human atherosclerotic lesions using [68Ga]Pentixafor PET/MRI. METHODS: Thirty-eight oncology patients underwent [68Ga]Pentixafor PET/MR imaging at baseline. Maximum standardized uptake values (SUVmax) were derived from hot lesions in seven arterial segments and target-to-blood ratios (TBR) were calculated. ANOVA post-hoc and paired t test were performed for statistical comparison, Spearman's correlation coefficient between uptake ratios and cardiovascular risk factors were assessed. The reproducibility of [68Ga]Pentixafor PET/MRI was assessed in seven patients with a follow-up exanimation by Pearson's regression and Bland-Altman plots analysis. RESULTS: Thirty-four of 38 patients showed 611 focal [68Ga]Pentixafor uptake that followed the contours of the large arteries. Both prevalence and mean TBRmax were highest in the descending aorta. There were significantly higher TBR values found in men (1.9 ± 0.3) as compared to women (1.7 ± 0.2; p < 0.05). Patients with mean TBRmax > 1.7 showed a significantly higher incidence of diabetes, hypertension hypercholesterolemia and history of cardiovascular disease than patients with mean TBRmax ≤ 1.7. [68Ga]Pentixafor uptake showed a good reproducibility (r = 0.6, p < 0.01), and there was no difference between the mean TBRmax values of plaque lesions (TBRbaseline1.8 ± 0.3 vs TBRfollow-up1.8 ± 0.3) (p = 0.9).

Seeing the unseen: post-infarction inflammation in an isolated right ventricular myocardial infarction visualized by combined cardiac magnetic resonance imaging and chemokine receptor CXCR4-targeted molecular imaging

Koenig T, Sedding DG, Wester HJ, Derlin T

14.03.2018 [Original Artikel]



CXCR4 Is a Potential Target for Diagnostic PET/CT Imaging in Barrett's Dysplasia and Esophageal Adenocarcinoma

Fang HY, Münch NS, Schottelius M, Ingermann J, Liu H, Schauer M, Stangl S, Multhoff G, Steiger K, Gerngroß C, Jesinghaus M, Weichert W, Kühl AA, Sepulveda AR, Wester HJ, Wang TC, Quante M

01.03.2018 [Original Artikel]

Purpose: Barrett's esophagus represents an early stage in carcinogenesis leading to esophageal adenocarcinoma. Considerable evidence supports a major role for chronic inflammation and diverse chemokine pathways in the development of Barrett's esophagus and esophageal adenocarcinoma.Experimental Design: Here we utilized an IL1β transgenic mouse model of Barrett's esophagus and esophageal adenocarcinoma and human patient imaging to analyze the importance of CXCR4-expressing cells during esophageal carcinogenesis.Results: IL1β overexpression induces chronic esophageal inflammation and recapitulates the progression to Barrett's esophagus and esophageal adenocarcinoma. CXCR4 expression is increased in both epithelial and immune cells during disease progression in pL2-IL1β mice and also elevated in esophageal adenocarcinoma patient biopsy samples. Specific recruitment of CXCR4-positive (CXCR4+) immune cells correlated with dysplasia progression, suggesting that this immune population may be a key contributor to esophageal carcinogenesis. Similarly, with progression to dysplasia, there were increased numbers of CXCR4+ columnar epithelial cells at the squamocolumnar junction (SCJ). These findings were supported by stronger CXCR4-related signal intensity in ex vivo fluorescence imaging and autoradiography with advanced dysplasia. Pilot CXCR4-directed PET/CT imaging studies in patients with esophageal cancer demonstrate the potential utility of CXCR4 imaging for the diagnosis and staging of esophageal cancer.Conclusion: In conclusion, the recruitment of CXCR4+ immune cells and expansion of CXCR4+ epithelial cells in esophageal dysplasia and cancer highlight the potential of CXCR4 as a biomarker and molecular target for diagnostic imaging of the tumor microenvironment in esophageal adenocarcinoma.

Imaging of C-X-C Motif Chemokine Receptor CXCR4 Expression After Myocardial Infarction With [68Ga]Pentixafor-PET/CT in Correlation With Cardiac MRI

Reiter T, Kircher M, Schirbel A, Werner RA, Kropf S, Ertl G, Buck AK, Wester HJ, Bauer WR, Lapa C

09.02.2018 [Original Artikel]


Targeting CXCR4 (CXC Chemokine Receptor Type 4) for Molecular Imaging of Aldosterone-Producing Adenoma

Heinze B, Fuss CT, Mulatero P, Beuschlein F, Reincke M, Mustafa M, Schirbel A, Deutschbein T, Williams TA, Rhayem Y, Quinkler M, Rayes N, Monticone S, Wild V, Gomez-Sanchez CE, Reis AC, Petersenn S, Wester HJ, Kropf S, Fassnacht M, Lang K, Herrmann K, Buck AK, Bluemel C, Hahner S

01.02.2018 [Original Artikel]

Primary aldosteronism is the most frequent cause of secondary hypertension and is associated with increased morbidity and mortality compared with hypertensive controls. The central diagnostic challenge is the differentiation between bilateral and unilateral disease, which determines treatment options. Bilateral adrenal venous sampling, currently recommended for differential diagnosis, is an invasive procedure with several drawbacks, making it desirable to develop novel noninvasive diagnostic tools. When investigating the expression pattern of chemokine receptors by quantitative real-time polymerase chain reaction and immunohistochemistry, we observed high expression of CXCR4 (CXC chemokine receptor type 4) in aldosterone-producing tissue in normal adrenals, adjacent adrenal cortex from adrenocortical adenomas, and in aldosterone-producing adenomas (APA), correlating strongly with the expression of CYP11B2 (aldosterone synthase). In contrast, CXCR4 was not detected in the majority of nonfunctioning adenomas that are frequently found coincidently. The specific CXCR4 ligand 68Ga-pentixafor has recently been established as radiotracer for molecular imaging of CXCR4 expression and showed strong and specific binding to cryosections of APAs in our study. We further investigated 9 patients with primary aldosteronism because of APA by 68Ga-pentixafor-positron emission tomography. The tracer uptake was significantly higher on the side of increased adrenocortical aldosterone secretion in patients with APAs compared with patients investigated by 68Ga-pentixafor-positron emission tomography for other causes. Molecular imaging of aldosterone-producing tissue by a CXCR4-specific ligand may, therefore, be a highly promising tool for noninvasive characterization of patients with APAs.

Clinical Molecular Imaging of Chemokine Receptor CXCR4 Expression in Atherosclerotic Plaque Using 68Ga-Pentixafor PET: Correlation with Cardiovascular Risk Factors and Calcified Plaque Burden

Weiberg D, Thackeray JT, Daum G, Sohns JM, Kropf S, Wester HJ, Ross TL, Bengel FM, Derlin T

01.02.2018 [Original Artikel]

The CXC-motif chemokine receptor 4 (CXCR4) represents a promising target for molecular imaging of different CXCR4-positive cell types in cardiovascular diseases such as atherosclerosis and arterial wall injury. The aim of this study was to assess the prevalence, pattern, and clinical correlates of arterial wall accumulation of 68Ga-pentixafor, a specific CXCR4 ligand for PET. Methods: The data for 51 patients who underwent 68Ga-pentixafor PET/CT for noncardiovascular indications were retrospectively analyzed. Tracer accumulation in the vessel wall of major arteries was analyzed qualitatively and semiquantitatively by blood-pool-corrected target-to-background ratios. Tracer uptake was compared with calcified plaque burden and cardiovascular risk factors. Results: Focal arterial uptake of 68Ga-pentixafor was seen at 1,411 sites in 51 (100%) of patients. 68Ga-pentixafor uptake was significantly associated with calcified plaque burden (P < 0.0001) and cardiovascular risk factors including age (P < 0.0001), arterial hypertension (P < 0.0001), hypercholesterolemia (P = 0.0005), history of smoking (P = 0.01), and prior cardiovascular events (P = 0.0004). Both the prevalence (P < 0.0001) and the signal intensity (P = 0.009) of 68Ga-pentixafor uptake increased as the number of risk factors increased. Conclusion:68Ga-pentixafor PET/CT is suitable for noninvasive, highly specific PET imaging of CXCR4 expression in the atherosclerotic arterial wall. Arterial wall 68Ga-pentixafor uptake is significantly associated with surrogate markers of atherosclerosis and is linked to the presence of cardiovascular risk factors. 68Ga-pentixafor signal is higher in patients with a high-risk profile and may hold promise for identification of vulnerable plaque.

68Ga-Pentixafor PET/CT Imaging of Chemokine Receptor CXCR4 in Chronic Infection of the Bone: First Insights

Bouter C, Meller B, Sahlmann CO, Staab W, Wester HJ, Kropf S, Meller J

01.02.2018 [Original Artikel]

Because of its role in infection and inflammatory processes, the chemokine receptor CXCR4 might be a potent target in imaging of infectious and inflammatory diseases. The aim of this pilot study was to determine whether the CXCR4 ligand 68Ga-pentixafor is suitable for imaging chronic infection of the bone. Methods: The study comprised 14 patients with suspected infection of the skeleton who underwent 68Ga-pentixafor PET/CT between April 2015 and February 2017 in our facility. 68Ga-pentixafor PET/CT results were retrospectively evaluated against a histologic, bacteriologic, and clinical standard. The results were also compared with available bone scintigraphy, white blood cell scintigraphy, and 18F-FDG PET/CT results. Results:68Ga-pentixafor PET/CT was positive in 9 of 14 patients. Diagnoses included osteitis or osteomyelitis of peripheral bone, osteomyelitis of the maxilla, and infected endoprostheses. Target-to-background ratios were 5.1-15 (mean, 8.7). Eight of 9 cases were true-positive as confirmed by pathology, bacteriology, or clinical observation. All negative cases were confirmed as true-negative by other imaging modalities and follow-up. Conclusion: Imaging of CXCR4 expression with 68Ga-pentixafor PET/CT appears suitable for diagnosing chronic infection of the skeleton. The findings of this study reveal a possible diagnostic gain in suspected chronic infections that are difficult to diagnose by other imaging modalities

Potential influence of concomitant chemotherapy on CXCR4 expression in receptor directed endoradiotherapy

Lapa C, Lückerath K, Kircher S, Hänscheid H, Grigoleit GU, Rosenwald A, Stolzenburg A, Kropf S, Einsele H, Wester HJ, Buck AK, Kortüm KM, Schirbel A

24.01.2018 [Original Artikel]

Dual Targeting of Acute Leukemia and Supporting Niche by CXCR4-Directed Theranostics

Habringer S, Lapa C, Herhaus P, Schottelius M, Istvanffy R, Steiger K, Slotta-Huspenina J, Schirbel A, Hänscheid H, Kircher S, Buck AK, Götze K, Vick B, Jeremias I, Schwaiger M, Peschel C, Oostendorp R, Wester HJ, Grigoleit GU, Keller U

01.01.2018 [Original Artikel]

C-X-C chemokine receptor 4 (CXCR4) is a transmembrane receptor with pivotal roles in cell homing and hematopoiesis. CXCR4 is also involved in survival, proliferation and dissemination of cancer, including acute lymphoblastic and myeloid leukemia (ALL, AML). Relapsed/refractory ALL and AML are frequently resistant to conventional therapy and novel highly active strategies are urgently needed to overcome resistance. Methods: We used patient-derived (PDX) and cell line-based xenograft mouse models of ALL and AML to evaluate the efficacy and toxicity of a CXCR4-targeted endoradiotherapy (ERT) theranostic approach. Results: The positron emission tomography (PET) tracer 68Ga-Pentixafor enabled visualization of CXCR4 positive leukemic burden. In xenografts, CXCR4-directed ERT with 177Lu-Pentixather distributed to leukemia harboring organs and resulted in efficient reduction of leukemia. Despite a substantial in vivo cross-fire effect to the leukemia microenvironment, mesenchymal stem cells (MSCs) subjected to ERT were viable and capable of supporting the growth and differentiation of non-targeted normal hematopoietic cells ex vivo. Finally, three patients with refractory AML after first allogeneic hematopoietic stem cell transplantation (alloSCT) underwent CXCR4-directed ERT resulting in leukemia clearance, second alloSCT, and successful hematopoietic engraftment. Conclusion: Targeting CXCR4 with ERT is feasible and provides a highly efficient means to reduce refractory acute leukemia for subsequent cellular therapies. Prospective clinical trials testing the incorporation of CXCR4 targeting into conditioning regimens for alloSCT are highly warranted.