Dual-responsive nanoplatform with feedback amplification improves antitumor efficacy of photodynamic therapy

A good photosensitizer (PS) delivery system could enhance efficiency and reduce side effects of anti-tumor photodynamic therapy (PDT) by improving accumulation in tumor, uptake by tumor cells, and intracellular release...

Design, Synthesis and Preclinical Assessment of 99mTc-iFAP for In Vivo Fibroblast Activation Protein (FAP) Imaging

Fibroblast activation protein (FAP) is expressed in the microenvironment of most human epithelial tumors. 68Ga-labeled FAP inhibitors based on the cyanopyrrolidine structure (FAPI) are currently used for the detection of the tumor microenvironment by PET imaging. This research aimed to design, synthesize and preclinically evaluate a new FAP inhibitor radiopharmaceutical based on the 99mTc-((R)-1-((6-hydrazinylnicotinoyl)-D-alanyl) pyrrolidin-2-yl) boronic acid (99mTc-iFAP) structure for SPECT imaging. Molecular docking for affinity calculations was performed using the AutoDock software. The chemical synthesis was based on a series of coupling reactions of 6-hidrazinylnicotinic acid (HYNIC) and D-alanine to a boronic acid derivative. The iFAP was prepared as a lyophilized formulation based on EDDA/SnCl2 for labeling with 99mTc. The radiochemical purity (R.P.) was verified via ITLC-SG and reversed-phase radio-HPLC. The stability in human serum was evaluated by size-exclusion HPLC. In vitro cell uptake was assessed using N30 stromal endometrial cells (FAP positive) and human fibroblasts (FAP negative). Biodistribution and tumor uptake were determined in Hep-G2 tumor-bearing nude mice, from which images were acquired using a micro-SPECT/CT. The iFAP ligand (Ki = 0.536 nm, AutoDock affinity), characterized by UV-Vis, FT-IR, 1H–NMR and UPLC-mass spectroscopies, was synthesized with a chemical purity of 92%. The 99mTc-iFAP was obtained with a R.P. >98%. In vitro and in vivo studies indicated high radiotracer stability in human serum (>95% at 24 h), specific recognition for FAP, high tumor uptake (7.05 ± 1.13% ID/g at 30 min) and fast kidney elimination. The results found in this research justify additional dosimetric and clinical studies to establish the sensitivity and specificity of the 99mTc-iFAP.

Translational imaging of the fibroblast activation protein (FAP) using the new ligand [68Ga]Ga-OncoFAP-DOTAGA

Purpose The fibroblast activation protein (FAP) is an emerging target for molecular imaging and therapy in cancer. OncoFAP is a novel small organic ligand for FAP with very high affinity. In this translational study, we establish [68Ga]Ga-OncoFAP-DOTAGA (68Ga-OncoFAP) radiolabeling, benchmark its properties in preclinical imaging, and evaluate its application in clinical PET scanning. Methods 68Ga-OncoFAP was synthesized in a cassette-based fully automated labeling module. Lipophilicity, affinity, and serum stability of 68Ga-OncoFAP were assessed by determining logD7.4, IC50 values, and radiochemical purity. 68Ga-OncoFAP tumor uptake and imaging properties were assessed in preclinical dynamic PET/MRI in murine subcutaneous tumor models. Finally, biodistribution and uptake in a variety of tumor types were analyzed in 12 patients based on individual clinical indications that received 163 ± 50 MBq 68Ga-OncoFAP combined with PET/CT and PET/MRI. Results 68Ga-OncoFAP radiosynthesis was accomplished with high radiochemical yields. Affinity for FAP, lipophilicity, and stability of 68Ga-OncoFAP measured are ideally suited for PET imaging. PET and gamma counting–based biodistribution demonstrated beneficial tracer kinetics and high uptake in murine FAP-expressing tumor models with high tumor-to-blood ratios of 8.6 ± 5.1 at 1 h and 38.1 ± 33.1 at 3 h p.i. Clinical 68Ga-OncoFAP-PET/CT and PET/MRI demonstrated favorable biodistribution and kinetics with high and reliable uptake in primary cancers (SUVmax 12.3 ± 2.3), lymph nodes (SUVmax 9.7 ± 8.3), and distant metastases (SUVmax up to 20.0). Conclusion Favorable radiochemical properties, rapid clearance from organs and soft tissues, and intense tumor uptake validate 68Ga-OncoFAP as a powerful alternative to currently available FAP tracers.

T908 Polymeric Micelles Improved the Uptake of Sgc8-c Aptamer Probe in Tumor-Bearing Mice: A Co-Association Study between the Probe and Preformed Nanostructures

Aptamers are oligonucleotides that have the characteristic of recognizing a target with high affinity and specificity. Based on our previous studies, the aptamer probe Sgc8-c-Alexa647 is a promising tool for molecular imaging of PTK7, which is an interesting biomarker in cancer. In order to improve the delivery of this probe as well as create a novel drug delivery nanosystem targeted to the PTK7 receptor, we evaluate the co-association between the probe and preformed nanostructures. In this work, preformed pegylated liposomes (PPL) and linear and branched pristine polymeric micelles (PMs), based on PEO–PPO–PEO triblock copolymers were used: poloxamer F127® and poloxamines T1307® and T908®. For it, Sgc8-c-Alexa647 and its co-association with the different nanostructures was exhaustively analyzed. DLS analysis showed nanometric sizes, and TEM and AFM showed notable differences between free- and co-associated probe. Likewise, all nanosystems were evaluated on A20 lymphoma cell line overexpressing PTK7, and the confocal microscopy images showed distinctness in cellular uptake. Finally, the biodistribution in BALB/c mice bearing lymphoma-tumor and pharmacokinetic study revealed an encouraging profile for T908-probe. All data obtained from this work suggested that PMs and, more specifically T908 ones, are good candidates to improve the pharmacokinetics and the tumor uptake of aptamer-based probes.

Radiolabeled Monoclonal Antibody Against Colony-Stimulating Factor 1 Receptor Specifically Distributes to the Spleen and Liver in Immunocompetent Mice

Macrophages can promote tumor development. Preclinically, targeting macrophages by colony-stimulating factor 1 (CSF1)/CSF1 receptor (CSF1R) monoclonal antibodies (mAbs) enhances conventional therapeutics in combination treatments. The physiological distribution and tumor uptake of CSF1R mAbs are unknown. Therefore, we radiolabeled a murine CSF1R mAb and preclinically visualized its biodistribution by PET. CSF1R mAb was conjugated to N-succinyl-desferrioxamine (N-suc-DFO) and subsequently radiolabeled with zirconium-89 (89Zr). Optimal protein antibody dose was first determined in non-tumor-bearing mice to assess physiological distribution. Next, biodistribution of optimal protein dose and 89Zr-labeled isotype control was compared with PET and ex vivo biodistribution after 24 and 72 h in mammary tumor-bearing mice. Tissue autoradiography and immunohistochemistry determined radioactivity distribution and tissue macrophage presence, respectively. [89Zr]Zr-DFO-N-suc-CSF1R-mAb optimal protein dose was 10 mg/kg, with blood pool levels of 10 ± 2% injected dose per gram tissue (ID/g) and spleen and liver uptake of 17 ± 4 and 11 ± 4%ID/g at 72 h. In contrast, 0.4 mg/kg of [89Zr]Zr-DFO-N-suc-CSF1R mAb was eliminated from circulation within 24 h; spleen and liver uptake was 126 ± 44% and 34 ± 7%ID/g, respectively. Tumor-bearing mice showed higher uptake of [89Zr]Zr-DFO-N-suc-CSF1R-mAb in the liver, lymphoid tissues, duodenum, and ileum, but not in the tumor than did 89Zr-labeled control at 72 h. Immunohistochemistry and autoradiography showed that 89Zr was localized to macrophages within lymphoid tissues. Following [89Zr]Zr-DFO-N-suc-CSF1R-mAb administration, tumor macrophages were almost absent, whereas isotype-group tumors contained over 500 cells/mm2. We hypothesize that intratumoral macrophage depletion by [89Zr]Zr-DFO-N-suc-CSF1R-mAb precluded tumor uptake higher than 89Zr-labeled control. Translation of molecular imaging of macrophage-targeting therapeutics to humans may support macrophage-directed therapeutic development.

Therapeutic Response of CCKBR-Positive Tumors to Combinatory Treatment with Everolimus and the Radiolabeled Minigastrin Analogue [177Lu]Lu-PP-F11N

The inhibition of the mammalian target of rapamycin complex 1 (mTORC1) by everolimus (RAD001) was recently shown to enhance the tumor uptake of radiolabeled minigastrin. In this paper, we investigate if this finding can improve the in vivo therapeutic response to [177Lu]Lu-PP-F11N treatment. The N-terminal DOTA-conjugated gastrin analogue PP-F11N (DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Nle-Asp-Phe) was used to evaluate treatment efficacy in the human A431/CCKBR xenograft nude mouse model in combination with RAD001. Both RAD001 and [177Lu]Lu-PP-F11N single treatments as well as their combination inhibited tumor growth and increased survival. In concomitantly treated mice, the average tumor size and median survival time were significantly reduced and extended, respectively, as compared to the monotherapies. The histological analysis of kidney and stomach dissected after treatment with RAD001 and [177Lu]Lu-PP-F11N did not indicate significant adverse effects. In conclusion, our study data demonstrate the potential of mTORC1 inhibition to substantially improve the therapeutic efficacy of radiolabeled minigastrin analogues in CCKBR-positive cancers.

Y90 Radioembolization of Liver Tumors via Radial approach – Correlation Between Common Femoral artery and Radial Artery Size

PurposeTypically, before Y90 radioembolization procedure undergoes, a CT is completed and the Barbeau test followed by radial artery ultrasound is used to determine if the artery is sufficiently large for vascular access [1-4]. 2.5 mm is the average radial artery diameter, and a vessel measurement of 2.0 mm is the recommended minimum diameter for safe vessel access, but a diameter of 1.5–2.0 mm can be accessed [4-9]. Our study explores using common femoral artery measurements from the pre-procedure CT abdomen/pelvis to assess in a binary manner if the vessel is sufficiently large to use for radial artery access. Materials and MethodsAll computed tomography scans of yttrium-90(Y90) radioembolization of the liver tumor procedures from January 1, 2015 - December 31, 2019 were retrospectively reviewed. Medical records were used from 47 procedures to gather patients' age, gender, Avastin use, femoral artery size (mm), administer Y90 (%), history of diabetes, and smoking status were recorded. ResultsThe minimum femoral artery size in patients who underwent transradial artery Y90 liver tumor radioembolization was 6 mm, with a mean femoral artery size of 10 mm. A comparative analysis of Y90 liver tumor uptake revealed no significant difference in radioembolization tumor uptake based on the initial site of procedure, transfemoral or transradial artery, (p > 0.81229). ConclusionThe study suggests that femoral arteries can predict radial artery diameter and that a femoral artery diameter of 10 mm should yield high confidence that the patient will be a candidate for transradial approach.

Biodistribution of phenylalanine labeled with gallium-68

Positron emission tomography (PET) is modern high sensitivity method of various tumor imaging. The synthesis of new radiopharmaceuticals based on amino acids and positron emitting radionuclide 68Ga for PET imaging is of great interest. This work is devoted to study the biodistribution of a new agent based on amino acid phenylalanine and 68Ga (68Ga-phenylalanine) in Wistar rats with cholangioma RS-1 after intravenous administration. A comparative investigation of 68Ga-phenylalanine and 68GaCl3 biodistribution was also carried out. It was shown that the highest uptake of 68Ga-phenylalanine was observed in blood, liver, femur and tumor. Tumor uptake of 68Ga-phenylalanine increased 3.5 times from 0.20 ± 0.03 % ID/g to 0.70 ± 0.10 % ID/g, whereas uptake of 68GaCl3 decreased from 0.34 ± 0.07 % ID/g to 0.13 ± 0.04 % ID/g within 3 h. Blood uptake of 68Ga-phenylalanine reached 2.98 ± 0.31 % ID/g. In other organs and tissues the uptake of 68Ga-phenylalanine didn’t exceed 1 % ID/g. Kidneys and femur uptake of 68Ga-phenylalanine was lower as compared with 68GaCl3, but in other organs the uptake of 68Ga-phenylalanine was similar or slightly higher when compared with 68GaCl3.

Biological behavior of a new 68Ga-labelled glucose derivative as a potential agent for tumor imaging

Glucose analogs and derivatives labeled with positron emitter 68Ga are considered to be a promising alternative to widely used radiotracer 18F-FDG for tumor PET imaging. In this study a biodistribution of a new glucose derivative labeled with 68Ga (68Ga-NODA-thioglucose) was investigated. All biodistribution studies were carried out in Balb/c mice with experimental model of tumor or aseptic inflammation. The tumor uptake of 68Ga-NODA-TG decreased throughout the study from 3.00±0.08 % ID/g to 1.06±0.04 %ID/g. The peak amount of 68Ga-NODA-TG in muscle with inflammation reached 4.33±0.12 % ID/g, decreasing to 0.23±0.08 % ID/g. In other organs and tissues the biodistribution of 68Ga-NODA-TG was similar in tumor-bearing mice and mice with aseptic inflammation. In conclusion, the obtained results suggest that 68Ga-NODA-TG has the potential for clinical application as a PET tracer.