Radiopharmaceutical therapy (RPT) is established as an innovative, effective, and well-tolerated treatment platform approved for well-differentiated neuroendocrine tumors and advanced prostate cancer (PC) and is being investigated in many other cancers such as breast, lung, and thyroid ([1][1]–[3

Extended cut-off filtration by medium cut-off membranes (MCO) has been shown to be safe in maintenance hemodialysis (HD). The notion of using them for the control of chronic low-grade inflammation and positively influencing cellular immune aberrations seems tempting. We conducted an open label, multicenter, randomized, 90 day 2-phase cross over clinical trial (MCO- vs. high flux-HD). 46 patients underwent randomization of which 34 completed the study. Dialysate- or pre- and post-dialysis serum inflammatory mediators were assayed for each study visit. Ex vivo T cell activation was assessed from cryopreserved leucocytes by flow cytometry. Linear mixed models were used to compare treatment modalities, with difference in pre-dialysis serum MCP-1 levels after 3 months as the predefined primary endpoint. Filtration/dialysate concentrations of most mediators, including MCP-1 (mean ± SD: 10.5 ± 5.9 vs. 5.1 ± 3.8 pg/ml, P < 0.001) were significantly increased during MCO- versus high flux-HD. However, except for the largest mediator studied, i.e., YKL-40, this did not confer any advantages for single session elimination kinetics (post-HD mean ± SD: 360 ± 334 vs. 564 ± 422 pg/ml, P < 0.001). No sustained reduction of any of the studied mediators was found neither. Still, the long-term reduction of CD69+ ( P = 0.01) and PD1+ ( P = 0.02) activated CD4+ T cells was striking. Thus, MCO-HD does not induce reduction of a broad range of inflammatory mediators studied here. Long-term reduction over a 3-month period was not possible. Increased single session filtration, as evidenced by increased dialysate concentrations of inflammatory mediators during MCO-HD, might eventually be compensated for by compartment redistribution or increased production during dialysis session. Nevertheless, lasting effects on the T-cell phenotype were seen, which deserves further investigation.

Immunological methods are widely applied in medical diagnostics for the detection and quantification of a plethora of analytes. Associated analytical challenges usually require these assays to be performed in a central laboratory. During the last several years, however, the clinical demand for rapid immunodiagnostics to be performed in the immediate proximity of the patient has been constantly increasing. Biosensors constitute one of the key technologies enabling the necessary, yet challenging transition of immunodiagnostic tests from the central laboratory to the point of care. This review is intended to provide insights into the current state of this transition process with a focus on the role of biosensor-based systems. To begin with, an overview on standard immunodiagnostic tests presently employed in the central laboratory and at the point of care is given. The review then moves on to demonstrate how biosensor technologies are reshaping this landscape. Single analyte as well as multiplexed immunosensors applicable to point of care scenarios are presented. A section on the areas of clinical application then creates the bridge to day-to-day diagnostic practice. Finally, the depicted developments are critically weighed and future perspectives discussed in order to give the reader a firm idea on the forthcoming trends to be expected in this diagnostic field.

The chemokine receptor 4 (CXCR4) is an important molecular target for both visualization and therapy of tumors. The aim of the present study was the synthesis and preclinical evaluation of a 64Cu-labeled, CXCR4-targeting peptide for positron emission tomography (PET) imaging of CXCR4 expression in vivo.

Purpose: Based on the clinical relevance of the chemokine receptor 4 (CXCR4) as a molecular target in cancer and on the success of [68Ga]pentixafor as an imaging probe for high-contrast visualization of CXCR4-expression, the spectrum of clinical CXCR4-targeting was expanded towards peptide receptor radionuclide therapy (PRRT) by the development of [177Lu]pentixather. Experimental design: CXCR4 affinity, binding specificity, hCXCR4 selectivity and internalization efficiency of [177Lu]pentixather were evaluated using different human and murine cancer cell lines. Biodistribution studies (1, 6, 48, 96h and 7d p.i.) and in vivo metabolite analyses were performed using Daudi-lymphoma bearing SCID mice. Extrapolated organ doses were cross-validated with human dosimetry (pre-therapeutic and during [177Lu]pentixather PRRT) in a patient with multiple myeloma (MM). Results: [177Lu]pentixather binds with high affinity, specificity and selectivity to hCXCR4 and shows excellent in vivo stability. Consequently, and supported by >96% plasma protein binding and a logP=-1.76, delaying whole-body clearance of [177Lu]pentixather, tumor accumulation was high and persistent, both in the Daudi model and the MM patient. Tumor/background ratios (7d p.i.) in mice were 499±202, 33±7, 4.0±0.8 and 116±22 for blood, intestine, kidney and muscle, respectively. In the patient, high tumor/kidney and tumor/liver dose ratios of 3.1 and 6.4 were observed during [177Lu]pentixather PRRT (7.8 GBq), with the kidneys being the dose-limiting organs. Conclusions: [177Lu]pentixather shows excellent in vivo CXCR4-targeting characteristics and a suitable pharmacokinetic profile, leading to high tumor uptake and retention and thus high radiation doses to tumor tissue during PRRT, suggesting high clinical potential of this [68Ga]pentixafor/[177Lu]pentixather based CXCR4-targeted theranostic concept.

BACKGROUND:The overexpression of the chemokine receptor 4 (CXCR4) in different epithelial, mesenchymal, and hematopoietic cancers makes CXCR4 an attractive diagnostic and therapeutic target. However, targeting the CXCR4 receptor with small cyclic pentapeptide-based radiopharmaceuticals remains challenging because minor structural modifications within the ligand-linker-chelate structure often significantly affect the receptor affinity. Based on the excellent in vivo properties of CXCR4-directed pentapeptide [(68)Ga]pentixafor (cyclo(-D-Tyr-N-Me-D-Orn(AMB-DOTA)-L-Arg-L-2-Nal-Gly-)), this study aims to broaden the spectrum of applicable (radio)metal-labeled pentixafor analogs.METHODS:Cyclic pentapeptides, based on the pentixafor scaffold, were synthesized by a combined solid- and solution-phase peptide synthesis. The CXCR4 receptor affinities of the cold reference compounds were determined in competitive binding assays using CXCR4-expressing Jurkat T - cell leukemia cells and [(125)I]FC131 as the radioligand.RESULTS:Metalated pentixafor derivatives with cyclic and acyclic chelators were synthesized by solid-phase peptide synthesis and evaluated in vitro. The resulting CXCR4 affinities (IC50) were highly dependent on the chelator and metal used. Two pentapeptides, Ga-NOTA and Bi-DOTA conjugates, offer an improved affinity compared to [(68)Ga]pentixafor.CONCLUSIONS:Based on the pentapeptide [(68)Ga]pentixafor, a broad range of metal-labeled analogs were investigated. The affinities of the new compounds were found to be strongly dependent on both the chelator and the metal used. Bi-labeled pentixafor showed high receptor affinity and seems to be a promising ligand for further preclinical evaluation and future α-emitter-based endoradiotherapy.

In vivo quantification of CXCR4 expression using [68Ga]pentixafor for positron emission tomography (PET) imaging has gained significant clinical interest as CXCR4 plays a fundamental role in oncology and possesses potential prognostic value when overexpressed. To combine the excellent CXCR4-targeting properties of pentixafor-based tracers with the favorable radionuclide properties of 18F for high-resolution PET imaging, we developed an Al18F-labeled 1,4,7-triazacyclononane-triacetic acid (NOTA) analog of pentixather. Al18F-labeling of NOTA-pentixather was performed in aqueous dimethyl sulfoxide (DMSO) at pH = 4 (105 °C, 15 minutes). CXCR4 affinities were determined in competitive binding assays, and both biodistribution and small-animal PET studies were performed in Daudi lymphoma-bearing mice. Under non-optimized conditions, [18F]AlF-NOTA-pentixather was obtained in radiochemical yields of 45.5% ± 13.3% and specific activities of up to 24.8 GBq/μmol. Compared with [natGa]pentixafor, [natF]AlF-NOTA-pentixather showed 1.4-fold higher CXCR4 affinity. [18F]AlF-NOTA-pentixather displayed high and CXCR4-specific in vivo uptake in Daudi xenografts (13.9% ± 0.8% injected dose per gram [ID/g] at 1 hour post injection [p.i.]). Because of its enhanced lipophilicity (logP = −1.4), [18F]AlF-NOTA-pentixather showed increased accumulation in the gall bladder and intestines. However, tumor/background ratios of 7.0 ± 1.2, 2.0 ± 0.3, 2.2 ± 0.4, 16.5 ± 6.5, and 29.2 ± 4 for blood, liver, small intestine, gut, and muscle, respectively, allowed for high-contrast visualization of Daudi tumors using PET (1 hour p.i.). The relatively straightforward radiosynthesis and efficient CXCR4 targeting of [18F]AlF-NOTA-pentixather demonstrate the successful implementation of 18F-complexation chemistry and pentixather-based CXCR4 targeting. Upon pharmacokinetic optimization, this class of tracers holds great promise for future application in humans.

68Ga-pentixafor is a radiotracer for PET that binds with nanomolar affinity to CXCR4. The CXCR4 receptor is expressed at the surface of inflammatory cells. The objective of the study was to analyze the ability of radiolabeled pentixafor to detect CXCR4 expression on inflammatory cells present in atherosclerotic plaques of an experimental rabbit model. Methods: Atherosclerotic plaques were induced by endothelial abrasion of the right carotid artery and abdominal aorta of 7 rabbits fed an atherogenic diet. Five noninjured rabbits fed a chow diet were used as controls. Rabbits were imaged on a PET/MR system after injection of 68Ga-pentixafor (15 MBq/kg). Vascular signal was quantified as tissue-to-background ratio (TBR). Biodistribution and autoradiographic studies were performed 1 h after injection of 125I-pentixafor (7.5 MBq/kg). In addition, blocking studies were performed in 2 atherosclerotic rabbits with preinjection of the CXCR4 inhibitor AMD3100. Tracer uptake was quantified on arterial cryosections using autoradiography and compared with CXCR4 and RAM-11 (macrophage) expression on adjacent histologic sections. Results: One hour after injection of 68Ga-pentixafor, strong signals were detected in vivo with PET/MR imaging in atherosclerotic plaques of the abdominal aorta and right carotid artery as compared with normal control arteries (mean TBR = 1.95 ± 0.51 vs. 1.22 ± 0.25 and mean TBR = 1.24 ± 0.38 vs. 0.96 ± 0.37, respectively; P < 0.05 for both). Blocking studies with preinjection of a CXCR4 inhibitor reduced 125I-pentixafor uptake in atherosclerotic plaques by approximately 40%. 125I-pentixafor uptake in the vessel wall on autoradiographies was located in macrophage-rich regions of atherosclerotic plaques and correlated with the intensity of CXCR4 expression on corresponding cryosections (r2 = 0.61; P < 0.05). Conclusion: 68Ga-pentixafor allows for the noninvasive detection of CXCR4 expression in the vessel wall with PET and emerges as a potential alternative to 18F-FDG for the assessment of macrophage infiltration in atherosclerotic plaques.

Due to its overexpression in a variety of tumor types, the chemokine receptor 4 (CXCR4) represents a highly relevant diagnostic and therapeutic target in nuclear oncology. Recently, [68Ga]pentixafor has emerged as an excellent imaging agent for positron emission tomography (PET) of CXCR4 expression in vivo. In this study, the corresponding [68Ga]-1,4,7-triazacyclononane-triacetic acid (NOTA) analog was preclinically evaluated and compared to the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) parent compound [68Ga]pentixafor.

Chemokine receptor 4 (CXCR4) is a key factor for tumor growth and metastasis in several types of human cancer. Based on promising experiences with a radiolabeled CXCR4 ligand (Ga-68-pentixafor) for diagnostic receptor targeting, Lu-177- and Y-60-pentixather were recently developed as endoradiotherapeutic vectors. Here, we summarize the first-in-human experience in 3 heavily pretreated patients with intramedullary and extensive extramedullary manifestations of multiple myeloma undergoing CXCR4-directed endoradiotherapy. Methods: CXCR4 target expression was demonstrated by baseline Ga-68-pentixafor PET. Each treatment was approved by the clinical ethics committee. Pretherapeutic Lu-177-pentixather dosimetry was performed before Lu-177-pentixather or Y-60-pentixather treatment. Subsequently, patients underwent additional chemotherapy and autologous stem cell transplantation for bone marrow rescue. Results: A remarkable therapeutic effect was visualized in 2 patients, who showed a significant reduction in F-18-FDG uptake. Conclusion: CXCR4-targeted radiotherapy with pentixather appears to be a promising novel treatment option in combination with cytotoxic chemotherapy and autologous stern cell transplantation, especially for patients with advanced multiple myeloma.

Cytokines are bioactive proteins produced by many different cells of the immune system. Due to their role in different inflammatory disease states and maintaining homeostasis, there is enormous clinical interest in the quantitation of cytokines. The typical standard methods for quantitation of cytokines are immunoassay-based techniques including enzyme-linked immusorbent assays (ELISA) and bead-based immunoassays read by either standard or modified flow cytometers. A review of recent developments in analytical methods for measurements of cytokine proteins is provided. This review briefly covers cytokine biology and the analysis challenges associated with measurement of these biomarker proteins for understanding both health and disease. New techniques applied to immunoassay-based assays are presented along with the uses of aptamers, electrochemistry, mass spectrometry, optical resonator-based methods. Methods used for elucidating the release of cytokines from single cells as well as in vivo collection methods are described.

Usually, the accessibility of 3-iodo-Tyr-containing peptides relies on the time-consuming de novo solid phase peptide synthesis. In this study, methods for the direct (mono)iodination of unprotected peptides were evaluated. The use of N-iodosuccinimide (NIS) in acetonitrile/water proved to be a particularly mild, fast (⩽5min) and efficient method with broad applicability to structurally diverse peptides. NIS iodination therefore represents a very practicable tool for the generation of iodinated peptides on a small (<1mg) to medium (1–20mg) scale in reasonable isolated yields (28±8%), providing easy and straightforward access to iodinated reference compounds, for example, for in vitro evaluation.