Human in vivo neuroimaging to detect reprogramming of the cerebral immune response following repeated systemic inflammation

Contains fulltext : 234408.pdf (Publisher’s version ) (Open Access

[89Zr]Zr-PSMA-617 PET/CT in biochemical recurrence of prostate cancer : first clinical experience from a pilot study including biodistribution and dose estimates

Purpose Prostate-specific membrane antigen (PSMA)-targeted PET/CT has become increasingly important in the management of prostate cancer, especially in localization of biochemical recurrence (BCR). PSMA-targeted PET/CT imaging with long-lived radionuclides as 89Zr (T1/2=78.4 h) may improve diagnostics by allowing data acquisition on later time points. In this study, we present our frst clinical experience including preliminary biodistribution and dosimetry data of [ 89Zr]Zr-PSMA-617 PET/CT in patients with BCR of prostate cancer. Methods Seven patients with BCR of prostate cancer who revealed no (n =4) or undetermined (n =3) findings on [ 68Ga]Ga-PSMA-11 PET/CT imaging were referred to [ 89Zr]Zr-PSMA-617 PET/CT. PET/CT imaging was performed 1 h, 24 h, 48 h, and 72 h post injection (p.i.) of 111±11 MBq [ 89Zr]Zr-PSMA-617 (mean±standard deviation). Normal organ distribution and dosimetry were determined. Lesions visually considered as suggestive of prostate cancer were quantitatively analyzed. Results Intense physiological uptake was observed in the salivary and lacrimal glands, liver, spleen, kidneys, intestine and urinary tract. The parotid gland received the highest absorbed dose (0.601±0.185 mGy/MBq), followed by the kidneys (0.517±0.125 mGy/MBq). The estimated overall efective dose for the administration of 111 MBq was 10.1 mSv (0.0913±0.0118 mSv/MBq). In 6 patients, and in particular in 3 of 4 patients with negative [ 68Ga]Ga-PSMA-11 PET/CT, at least one prostate cancer lesion was detected in [ 89Zr]Zr-PSMA-617 PET/CT imaging at later time points. The majority of tumor lesions were frst visible at 24 h p.i. with continuously increasing tumor-to-background ratio over time. All tumor lesions were detectable at 48 h and 72 h p.i. Conclusion [ 89Zr]Zr-PSMA-617 PET/CT imaging is a promising new diagnostic tool with acceptable radiation exposure for patients with prostate cancer especially when [ 68Ga]Ga-PSMA-11 PET/CT imaging fails detecting recurrent disease. The long half-life of 89Zr enables late time point imaging (up to 72 h in our study) with increased tracer uptake in tumor lesions and higher tumor-to-background ratios allowing identifcation of lesions non-visible on [ 68Ga]Ga-PSMA-11 PET/CT imaging

Towards personalized treatment of prostate cancer: PSMA I&T, a promising prostate-specific membrane antigen-targeted theranostic agent

Prostate-specific membrane antigen (PSMA) is a well-established target for nuclear imaging and therapy of prostate cancer (PCa). Radiolabeled small-molecule PSMA inhibitors are excellent candidates for PCa theranostics-they rapidly and efficiently localize in tumor lesions. However, high tracer uptake in kidneys and salivary glands are major concerns for therapeutic applications. Here, we present the preclinical application of PSMA I&T, a DOTAGA-chelated urea-based PSMA inhibitor, for SPECT/CT imaging and radionuclide therapy of PCa. 111In-PSMA I&T showed dose-dependent uptake in PSMA-expressing tumors, kidneys, spleen, adrenals, lungs and salivary glands. Coadministration of 2-(phosphonomethyl)pentane-1,5-dioic acid (2-PMPA) efficiently reduced PSMA-mediated renal uptake of 111In-PSMA I&T, with the highest tumor/kidney radioactivity ratios being obtained using a dose of 50 nmol 2-PMPA. SPECT/CT clearly visualized subcutaneous tumors and sub-millimeter intraperitoneal metastases; however, high renal and spleen uptake in control mice (no 2-PMPA) interfered with visualization of metastases in the vicinity of those organs. Coadministration of 2-PMPA increased the tumor-to-kidney absorbed dose ratio during 177Lu-PSMA I&T radionuclide therapy. Hence, at equivalent absorbed dose to the tumor (36 Gy), coinjection of 2-PMPA decreased absorbed dose to the kidneys from 30 Gy to 12 Gy. Mice injected with 177Lu-PSMA I&T only, showed signs of nephrotoxicity at 3 months after therapy, whereas mice injected with 177Lu-PSMA I&T + 2-PMPA did not. These data indicate that PSMA I&T is a promising theranostic tool for PCa. PSMA-specific uptake in kidneys can be successfully tackled using blocking agents such as 2-PMPA

Targeting human prostate cancer with In-111-labeled D2B IgG, F(ab ')(2) and Fab fragments in nude mice with PSMA-expressing xenografts

D2B is a new monoclonal antibody directed against an extracellular domain of prostate-specific membrane antigen (PSMA), which is overexpressed in prostate cancer. The potential of D2B IgG, and F(ab)(2) and Fab fragments of this antibody for targeting prostate cancer was determined in mice bearing subcutaneous prostate cancer xenografts. The optimal time point for imaging was determined in biodistribution and microSPECT imaging studies with In-111-D2B IgG, In-111-capromab pendetide, In-111-D2B F(ab)(2) and In-111-D2B Fab fragments in mice with PSMA-expressing LNCaP and PSMA-negative PC3 tumors at several time points after injection. All In-111-labeled antibody formats specifically accumulated in the LNCaP tumors, with highest uptake of In-111-D2B IgG and In-111-capromab pendetide at 168h p.i. (94.8 +/- 19.2% injected dose per gram (ID/g) and 16.7 +/- 2.2% ID/g, respectively), whereas uptake of In-111-D2B F(ab)(2) and In-111-D2B Fab fragments peaked at 24h p.i. (12.1 +/- 3.0% ID/g and 15.1 +/- 2.9% ID/g, respectively). Maximum LNCaP tumor-to-blood ratios were 13.0 +/- 2.3 (168h p.i.), 6.2 +/- 0.7 (24h p.i.), 23.0 +/- 4.0 (24h p.i.) and 4.5 +/- 0.6 (168h p.i.) for In-111-D2B IgG, In-111-F(ab)(2), In-111-Fab and In-111-capromab pendetide, respectively. LNCaP tumors were clearly visualized with microSPECT with all antibody formats. This study demonstrates the feasibility of D2B IgG, F(ab)(2) and Fab fragments for targeting PSMA-expressing prostate cancer xenografts. Copyright (c) 2014 John Wiley & Sons, Ltd

Novel VHH-Based Tracers with Variable Plasma Half-Lives for Imaging of CAIX-Expressing Hypoxic Tumor Cells

Hypoxic areas are present in the majority of solid tumors, and hypoxia is associated with resistance to therapies and poor outcomes. A transmembrane protein that is upregulated by tumor cells that have adapted to hypoxic conditions is carbonic anhydrase IX (CAIX). Therefore, noninvasive imaging of CAIX could be of prognostic value, and it could steer treatment strategies. The aim of this study was to compare variants of CAIX-binding VHH B9, with and without a C-terminal albumin-binding domain with varying affinity (ABDlow and ABDhigh), for SPECT imaging of CAIX expression. The binding affinity and internalization of the various B9-variants were analyzed using SK-RC-52 cells. Biodistribution studies were performed in mice with subcutaneous SCCNij153 human head and neck cancer xenografts. Tracer uptake was determined by ex vivo radioactivity counting and visualized by SPECT/CT imaging. Furthermore, autoradiography images of tumor sections were spatially correlated with CAIX immunohistochemistry. B9-variants demonstrated a similar moderate affinity for CAIX in vitro. Maximal tumor uptake and acceptable tumor-to-blood ratios were found in the SCCNij153 model at 4 h post injection for [111In]In-DTPA-B9 (0.51 ± 0.08%ID/g and 8.1 ± 0.85, respectively), 24 h post injection for [111In]In-DTPA-B9-ABDlow (2.39 ± 0.44%ID/g and 3.66 ± 0.81, respectively) and at 72 h post injection for [111In]In-DTPA-B9-ABDhigh (8.7 ± 1.34%ID/g and 2.43 ± 0.15, respectively). An excess of unlabeled monoclonal anti-CAIX antibody efficiently inhibited tumor uptake of [111In]In-DTPA-B9, while only a partial reduction of [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh uptake was found. Immunohistochemistry and autoradiography images showed colocalization of all B9-variants with CAIX expression; however, [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh also accumulated in non-CAIX expressing regions. Tumor uptake of [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh, but not of [111In]In-DTPA-B9, could be visualized with SPECT/CT imaging. In conclusion, [111In]In-DTPA-B9 has a high affinity to CAIX and shows specific targeting to CAIX in head and neck cancer xenografts. The addition of ABD prolonged plasma half-life, increased tumor uptake, and enabled SPECT/CT imaging. This uptake was, however, partly CAIX- independent, precluding the ABD-tracers for use in hypoxia quantification in this tumor type

Preclinical evaluation of two 68Ga-siderophores as potential radiopharmaceuticals for Aspergillus fumigatus infection imaging

PURPOSE: Invasive pulmonary aspergillosis is mainly caused by Aspergillus fumigatus, and is one of the major causes of morbidity and mortality in immunocompromised patients. The mortality associated with invasive pulmonary aspergillosis remains high, mainly due to the difficulties and limitations in diagnosis. We have shown that siderophores can be labelled with (68)Ga and can be used for PET imaging of A. fumigatus infection in rats. Here we report on the further evaluation of the most promising (68)Ga-siderophore candidates, triacetylfusarinine (TAFC) and ferrioxamine E (FOXE). METHODS: Siderophores were labelled with (68)Ga using acetate buffer. Log P, protein binding and stability values were determined. Uptake by A. fumigatus was studied in vitro in cultures with high and low iron loads. In vivo biodistribution was determined in normal mice and an infection model was established using neutropenic rats inoculated with A. fumigatus. Static and dynamic muPET imaging was performed and correlated with CT images, and lung infection was evaluated ex vivo. RESULTS: (68)Ga-siderophores were labelled with high radiochemical purity and specific activity. (68)Ga-TAFC and (68)Ga-FOXE showed high uptake by A. fumigatus in iron-deficient cultures. In normal mice, (68)Ga-TAFC and (68)Ga-FOXE showed rapid renal excretion with high metabolic stability. In the rat infection model focal lung uptake was detected by muPET with both compounds and increased with severity of the infection, correlating with abnormal CT images. CONCLUSION: (68)Ga-TAFC and (68)Ga-FOXE displayed excellent in vitro stability and high uptake by A. fumigatus. Both compounds showed excellent pharmacokinetics, highly selective accumulation in infected lung tissue and good correlation with severity of disease in a rat infection model, which makes them promising agents for A. fumigatus infection imaging

PET imaging of αvβ3 integrin expression in tumours with 68Ga-labelled mono-, di- and tetrameric RGD peptides

Contains fulltext : 97195.pdf (publisher's version ) (Closed access)PURPOSE: Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3)-binding characteristics of (68)Ga-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their (111)In-labelled counterparts. METHODS: A monomeric (E-c(RGDfK)), a dimeric (E-[c(RGDfK)](2)) and a tetrameric (E{E[c(RGDfK)](2)}(2)) RGD peptide were synthesised, conjugated with DOTA and radiolabelled with (68)Ga. In vitro alpha(v)beta(3)-binding characteristics were determined in a competitive binding assay. In vivo alpha(v)beta(3)-targeting characteristics of the compounds were assessed in mice with subcutaneously growing SK-RC-52 xenografts. In addition, microPET images were acquired using a microPET/CT scanner. RESULTS: The IC(50) values for the Ga(III)-labelled DOTA-E-c(RGDfK), DOTA-E-[c(RGDfK)](2) and DOTA-E{E[c(RGDfK)](2)}(2) were 23.9 +/- 1.22, 8.99 +/- 1.20 and 1.74 +/- 1.18 nM, respectively, and were similar to those of the In(III)-labelled mono-, di- and tetrameric RGD peptides (26.6 +/- 1.15, 3.34 +/- 1.16 and 1.80 +/- 1.37 nM, respectively). At 2 h post-injection, tumour uptake of the (68)Ga-labelled mono-, di- and tetrameric RGD peptides (3.30 +/- 0.30, 5.24 +/- 0.27 and 7.11 +/- 0.67%ID/g, respectively) was comparable to that of their (111)In-labelled counterparts (2.70 +/- 0.29, 5.61 +/- 0.85 and 7.32 +/- 2.45%ID/g, respectively). PET scans were in line with the biodistribution data. On all PET scans, the tumour could be clearly visualised. CONCLUSION: The integrin affinity and the tumour uptake followed the order of DOTA-tetramer > DOTA-dimer > DOTA-monomer. The (68)Ga-labelled tetrameric RGD peptide has excellent characteristics for imaging of alpha(v)beta(3) expression with PET

Comparison of three remote radiolabelling methods for long-circulating liposomes

Long-circulating liposomes (LCL) are often used as a drug carrier system to improve the therapeutic index of water-soluble drugs. To track these LCL in vivo, they can be radiolabelled with 111In-oxine. For this labellingmethod, generally DTPA is encapsulated in the aqueous phase of LCL (DTPA-LCL). Alternatively, LCL can be labelled with 111InCl3 after incorporation of DTPA-conjugated DSPE in the lipid bilayer (DTPA-DSPE LCL). Here, we compared the in vitro properties of DTPA-DSPE LCLwith those of DTPA LCL and empty LCL. Additionally, we compared the in vivo performance of DTPA-DSPE LCL with those of DTPA LCL in mice. DTPA LCL (88 nm) and empty LCL (84 nm) were labelled with 111In-oxine, and DTPA-DSPE LCL (83 nm) were labelled with 111InCl3. Labelling efficiency at increasing specific activity was determined. In vitro stability of 111In-labelled LCL was determined in human serum at 37 °C. The in vivo properties of 111In-labelled LCL were determined in mice with a Staphylococcus aureus infection in the thigh muscle. Image acquisition, blood sampling and biodistribution studies were performed 1, 4 (blood sampling only), 24, 48 and 72 h p.i. of 111In-labelled LCL. DTPA-DSPE LCL could be labelled efficiently at a much higher specific activity compared to DTPA LCL and empty LCL: >90% at 15 GBq/mmol, >90% at 150 MBq/mmol and 6065% at 150 MBq/mmol, respectively. 111In-labelled DTPA-DSPE LCL and DTPA LCL were stable in human serum, regarding label retention, for at least 48 h at 37 °C (>98% retention of the radiolabel). In contrast, only 68% radiolabel was retained in empty LCL after 48 h. In vivo targeting of 111In-DTPA-DSPE LCL to the abscess was comparable to targeting of 111In-DTPA LCL (3.5 ± 0.9%ID/g and 3.4 ± 0.9%ID/g abscess uptake respectively, 48 h p.i.). In conclusion, labelling of DTPA-DSPE LCL with 111InCl3 represents a robust, easy and fast procedurewhich is preferred over the more laborious conventional labelling of DTPA-LCL with 111In-oxine