Design, Synthesis, and Biological Evaluation of Novel Nonsteroidal 18F-Labeled PET Probes Specifically Targeting Estrogen Receptor α.

The estrogen receptor α positive (ERα+) subtype represents nearly 70% of all breast cancers (BCs), which seriously threaten women's health. Positron emission computed tomography (PET) characterizes its superiority in detecting the recurrence and metastasis of BC. In this article, an array of novel PET probes ([18F]R-1, [18F]R-2, [18F]R-3, and [18F]R-4) targeting ERα based on the tetrahydropyridinyl indole scaffold were developed. Among them, [18F]R-3 and [18F]R-4 showed good target specificity toward ERα and could distinguish MCF-7 (ERα+) and MDA-MB-231 (ERα-) tumors efficiently. Especially, [18F]R-3 could differentiate the ERα positive/negative tumors successfully with a higher tumor-to-muscle uptake ratio (T/M) than that of [18F]R-4. The radioactivity of [18F]R-3 in the MCF-7 tumor was 5.24 ± 0.84%ID/mL and its T/M ratio was 2.49 ± 0.62 at 25 min postinjection, which might be the optimal imaging time point in PET scanning. On the contrary, [18F]R-3 did not accumulate in the MDA-MB-231 tumor at all. The autoradiography analysis of [18F]R-3 on the MCF-7 tumor-bearing mice model was consistent with the PET imaging results. [18F]R-3 exhibited the pharmacokinetic property of rapid distribution and slow clearance, making it suitable for use as a diagnostic PET probe. Overall, [18F]R-3 was capable of serving as a PET radiotracer to delineate the ERα+ tumor and was worthy of further exploitation.

Preparation and Bioevaluation of 18F-Labeled Small-Molecular Radiotracers via Sulfur(VI) Fluoride Exchange Chemistry for Imaging of Programmed Cell Death Protein Ligand 1 Expression in Tumors.

Nowadays, one of the most effective methods of tumor immunotherapy is blocking programmed cell death protein 1/programmed cell death protein ligand 1 (PD-1/PD-L1) immune checkpoints. However, there is still a significant challenge in selecting patients to benefit from immune checkpoint therapies. Positron emission tomography (PET), a noninvasive molecular imaging technique, offers a new approach to accurately detect PD-L1 expression and allows for a better prediction of response to PD-1/PD-L1 target immunotherapy. Here, we designed and synthesized a novel group of aryl fluorosulfate-containing small-molecule compounds (LGSu-1, LGSu-2, LGSu-3, and LGSu-4) based on the phenoxymethyl-biphenyl scaffold. After screening by the time-resolved fluorescence resonance energy transfer (TR-FRET) assay, the most potent compound LGSu-1 (half maximal inhibitory concentration (IC50): 15.53 nM) and the low-affinity compound LGSu-2 (IC50: 189.70 nM) as a control were selected for 18F-radiolabeling by sulfur(VI) fluoride exchange chemistry (SuFEx) to use for PET imaging. [18F]LGSu-1 and [18F]LGSu-2 were prepared by a one-step radiofluorination reaction in over 85% radioconversion and nearly 30% radiochemical yield. In B16-F10 melanoma cell assays, [18F]LGSu-1 (5.00 ± 0.06%AD) showed higher cellular uptake than [18F]LGSu-2 (2.55 ± 0.04%AD), in which cell uptake could be significantly blocked by the nonradioactivity LGSu-1. In vivo experiments, micro-PET imaging of B16-F10 tumor-bearing mice and radiographic autoradiography of tumor sections showed that [18F]LGSu-1 was more effectively accumulated in the tumor due to the higher binding affinity with PD-L1. The above experimental results confirmed the potential of the small-molecule probe LGSu-1 as a targeting PD-L1 imaging tracer in tumor tissues.

Stimuli-Responsive Macrocyclization Scaffold Allows In Situ Self-Assembly of Radioactive Tracers for Positron Emission Tomography Imaging of Enzyme Activity.

Target-enabled bioorthogonal reaction and self-assembly of a small-molecule probe into supramolecules have shown promise for molecular imaging. In this paper, we report a new stimuli-responsive bioorthogonal reaction scaffold (SF) for controlling in situ self-assembly by engineering the condensation reaction between 2-cyanobenzothiazole and cysteine. For probes with the SF scaffold, intramolecular cyclization took place soon after activation, which could efficiently outcompete free cysteine even at a low concentration and result in efficient aggregation in the target. Through integration with different enzyme-responsive substrates and an ammoniomethyl-trifluoroborate moiety (AmBF3), two radioactive positron emission tomography (PET) tracers, [18F]SF-DEVD and [18F]SF-Glu, were designed, which showed high stability under physiological conditions and could produce clear PET signal in tumors to detect enzyme activity (e.g., caspase-3, γ-glutamyltranspeptidase) timely and accurately. Our results demonstrated that the scaffold SF could serve as a general molecular scaffold in the development of smart PET tracers for noninvasive imaging of enzyme activity, which could contribute to tumor detection and treatment efficacy evaluation.

Immuno-PET imaging of 68Ga-labeled nanobody Nb109 for dynamic monitoring the PD-L1 expression in cancers.

The checkpoint blockade immunotherapy has become a potent treatment strategy for cancers, and programmed death ligand-1 (PD-L1) is a prominent checkpoint ligand that is highly expressed in some cancers. The identification of immune checkpoint marker PD-L1 is critical for improving the success of immunotherapy. Accordingly, the binding specificity and dynamic monitoring property of a non-blocking nanobody tracer 68Ga-NOTA-Nb109 to PD-L1 were assessed in this study. The endogenous expression level of PD-L1 in several cancer cells was measured by flow cytometry, Western blot, and cellular uptake assay. Sensitivity and specificity of 68Ga-NOTA-Nb109 in monitoring the expression of PD-L1 in vivo were evaluated by PET imaging of different tumor-bearing models (U87, high PD-L1 expression; HCT 116, medium PD-L1 expression; and NCI-H1299, low PD-L1 expression). In vivo PET imaging results agreed well with those detected in vitro. In addition, PET imaging of PD-L1 expression in U87 and NCI-H1299 xenografts using 18F-FDG was also performed for comparison. The maximum tumor-to-muscle uptake ratio of 68Ga-NOTA-Nb109 was more than twofold that of 18F-FDG in U87 xenograft. The change of PD-L1 expression in NCI-H1299 cells and xenografts induced by cisplatin (CDDP) was sensitively monitored by 68Ga-NOTA-Nb109. This study demonstrated the feasibility of tracer 68Ga-NOTA-Nb109 for specifically targeting endogenous PD-L1 and dynamic monitoring the change of PD-L1 expression, and could guide the immunotherapy and immunochemotherapy for refractory cancers.

Promising potential of a 18F-labelled small-molecular radiotracer to evaluate PD-L1 expression in tumors by PET imaging.

Programmed death ligand 1 (PD-L1) expression level is a reproducible biomarker for guiding stratification of patients to immunotherapy. However, the most widely used immunohistochemistry method is incompetent to fully understand the PD-L1 expression level in the whole body because of the highly complex PD-L1 expression in the tumor microenvironment. In this work, a novel small-molecular radiotracer [18F]LG-1 based on the biphenyl active structure was developed to evaluate PD-L1 expression in tumors. [18F]LG-1 was obtained by conjugating and radiolabeling with [18F]FDG with high radiochemical purity (>98.0%) and high molar activity (37.2 ± 2.9 MBq/nmol). In vitro experimental results showed that [18F]LG-1 could target PD-L1 in tumor cells and the cellular uptake in A375-hPD-L1 cells (PD-L1 + ) was clearly higher than that in A375 cells (PD-L1-). In vivo dynamic PET images of [18F]LG-1 provided clear visualization of A375-hPD-L1 tumor with high tumor-to-background contrast, and the tumor uptake was determined to be 3.98 ± 0.21 %ID/g at 60 min, which was 2.6-fold higher than that of A375 tumor. These results suggested that [18F]LG-1 had great potential as a promising PD-L1 radiotracer.

Radiofluorinated Smart Probes for Noninvasive PET Imaging of Legumain Activity in Living Subjects.

Overexpression of legumain is closely associated with tumor proliferation, invasion, and metastasis. Because of its intrinsic properties, such as high sensitivity and resolution, positron emission tomography (PET) has become an effective imaging technique for early diagnosis, treatment response prediction, and monitoring. Herein, two legumain-targeting radiofluorinated smart probes (18F-2 and 18F-3) as well as a control probe (18F-1) were specifically designed for PET imaging of legumain activity in tumors. 18F-1, 18F-2, and 18F-3 were obtained with high radiochemical yield (RCY > 60%) and radiochemical purity (RCP > 99%) using a convenient "one-step" 18F-labeling method. The probes 18F-2 and 18F-3 exhibited high response to legumain activity and reductive environment and revealed comparable uptake in HCT116 cells (4.22% ± 0.14% and 4.64% ± 0.32% for 18F-2 and 18F-3, respectively; 8.46% ± 0.33% and 9.05% ± 0.24% for co-treatment of 18F-2 + 2 and 18F-3 + 3 at 1 h), while the control probe 18F-1 showed no response. PET imaging of tumor-bearing mice showed that the co-injection strategy (18F-2 + 2 and 18F-3 + 3) resulted in higher tumor uptake (3.57% ± 0.37% and 3.72% ± 0.19% ID/g at 10 min, respectively) than the single injection strategy (2.59% ± 0.19% and 2.60% ± 0.46% ID/g for 18F-2 and 18F-3, respectively). In addition, introduction of the trimeric histidine-glutamate (HEHEHE) tag to 18F-3 reduced the liver uptake by almost two-fold without any noticeable effect on the tumor uptake. All the results indicate that 18F-3 holds great potential applications in clinics for sensitive and specific PET imaging of legumain activity in tumors.

One-step radiosynthesis and initial evaluation of a small molecule PET tracer for PD-L1 imaging.

Programmed cell death protein-ligand 1 (PD-L1) is a crucial biomarker in immunotherapy and its expression level plays a key role in the guidance of anti-PD-L1 therapy. It had been reported that PD-L1 was quantified by noninvasive imaging with more developed radiotracers. In our study, a novel [18F]fluoride labeled small molecule inhibitor, [18F]LN was designed for positron emission tomography (PET) imaging in both PD-L1 transfected (A375-hPD-L1) and non-transfected (A375) melanoma-bearing mice. LN showed the specificity (IC50 = 50.39 ± 2.65 nM) to PD-L1 confirmed by competitive combination and cell flow cytometry (FACS) analysis. The radiotracer [18F]LN was obtained via 18F-19F isotope exchange from precursor LN. After radiosynthesis, [18F]LN was achieved with a high radiochemical purity (RCP) above 95% and got a favorable molar activity of 36.34 ± 5.73 GBq/µmol. [18F]LN displayed the moderate affinity (Kd = 65.27 ± 3.47 nM) to PD-L1 by specific binding assay. And it showed 1.3-fold higher uptake in A375-hPD-L1 cells than that in A375 cells. PET imaging revealed that [18F]LN could enter into PD-L1 expressing tumor site and visualize the outline of tumor. And tumor uptake (1.96 ± 0.27 %ID/g) reached the maximum at 15 min in the positive group, showed 2.2-fold higher than the negative (0.89 ± 0.31 %ID/g) or the blocked (1.07 ± 0.26 %ID/g) groups. Meanwhile, biodistribution could slightly distinguish the positive from the negative. The results indicated [18F]LN would become an efficient tool for evaluating PD-L1 expression with further optimization.

Radiopharmacological evaluation of a caspase-3 responsive probe with optimized pharmacokinetics for PET imaging of tumor apoptosis.

Early evaluation of the therapy efficiency can promote the development of anti-tumor drugs and optimization of the treatment method. Caspase-3 is a key biomarker for early apoptosis. Detection of caspase-3 activity is essential for quick assessment of the curative effect. We have reported a PET probe that could image drug-induced tumor apoptosis in vivo. However, high liver uptake limits its application. In order to optimize the pharmacokinetics of the previous probe, we introduced a hydrophilic peptide sequence to minimize liver uptake. The structure of the new probe was confirmed by mass spectrometry and nuclear magnetic resonance. This probe was able to cross the cell membrane freely and could be converted into a dimer through the condensation reaction of 2-cyano-6-aminobenzothiazole (CBT) and cysteine in response to intracellular activated caspase-3 and glutathione (GSH). The hydrophobic dimers further self-assembled into nanoparticles, which could enhance the probe aggregation in apoptotic tumor tissues. In vivo experiments showed that the tumor uptake of the new probe was higher than that of the previous probe, while the liver uptake of the new probe was significantly reduced. The new probe might be promising in imaging apoptotic tumors with suitable pharmacokinetics.

Targeted Delivery of an Activatable Fluorescent Probe for the Detection of Furin Activity in Living Cells.

Furin, a protein convertase, plays a crucial role in the progression of tumors. In this work, a new fluorescent probe consisting of a peptide, Arg-Val-Arg-Arg (RVRR), and an aminoluciferin fluorophore was designed and prepared for the responsive and activatable detection of furin activity in vitro and in living cells. We demonstrated that this probe could be responsive toward furin with an "off-on" florescence signal and generated an approximately 3.58-fold enhancement in the fluorescence intensity in vitro. Fluorescence imaging in MDA-MB-468 and LoVo cells showed that the probe could be cleaved by overexpressed furin with fluorescence turn-on in MDA-MB-468 cells, and this probe was also found to be capable of discriminating between furin-overexpressing and furin-deficient cell lines. Our research indicates that this probe has great potential for the detection of furin activity in living cells.

Enhanced Tumor Diagnostic and Therapeutic Effect of Mesoporous Silica Nanoparticle-Mediated Pre-targeted Strategy.

PURPOSE: Improving the targeting efficiency of imaging agents or anticancer drugs has become essential in the current primary mission to enhance the diagnostic or therapeutic effects. To improve the tumor diagnosis and therapy effect, a promising drug-delivery and targeting strategy was established based on the bioorthogonal chemistry. METHOD: The delivery system was composed of the pre-targeting carrier Biotin-MSNs-DBCO nanoparticles and the azido cargoes. The fluorescence probe 1-(3-azidopropyl) fluorescein (FITC-N3) and ruthenium N-heterocyclic carbene complex N3-S-S-NHC-Ru were synthesized and served as the tumor imaging and therapy probes, respectively. The cell imaging and viability was investigated by the Biotin-MSNs-DBCO pre-targeted for 4 h in colonic carcinoma (HeLa) cells. RESULTS: For the tumor cell imaging, Biotin-MSNs-DBCO could react with FITC-N3 rapidly and completely in 20 min with 93% yields. The fluorescence intensity of tumor cells was obviously increased by the Biotin-MSNs-DBCO pre-targeted. The cytotoxicity of the ruthenium complex N3-S-S-NHC-Ru was significantly improved appropriately three times with the IC50 (half inhibitory concentration) value of 6.68 ± 1.29 µM and enhancement of the mitochondrial dysfunction. CONCLUSIONS: The pre-targeting nanoparticle Biotin-MSNs-DBCO could selectively capture the azido compounds in tumor cells, which provided a site-specific target for the cargoes and then resulted in an enhancement of diagnostic or therapeutic effects.

131 I radiolabeled immune albumin nanospheres loaded with doxorubicin for in vivo combinatorial therapy.

For the purpose of providing new insights for high-efficiency radiochemotherapy of hepatoma, a radioimmunotherapy and chemotherapy combinatorial therapy albumin nanospheres 131 I-antiAFPMcAb-DOX-BSA-NPs was designed and prepared. It was obtained in a high radiolabeling yield approximately 65% with the radiochemical purity of over 98%. The transmission electron microscope showed that the nanospheres obtained in good monodispersion with a diameter of approximately 230 nm. The doxorubicin (DOX) loading capacity of the DOX-BSA-NPs nanoparticles was determined to be approximately 180 µg/mg and 95.79 ± 3.89%. DOX was released gradually in 6 days. In vivo tumor-growth inhibition experiments showed that after treating with 131 I-antiAFPMcAb-DOX-BSA-NPs for 14 days, the tumor volume decreased more obvious than that of other 2 time points and the control groups. All the results indicated that the radiolabeled immune albumin nanospheres 131 I-antiAFPMcAb-DOX-BSA-NPs could significantly inhibit the hepatoma tumor growth with the strategy of combinatorial radioimmunotherapy and chemotherapy.

Synthesis and preliminary biological evaluation of a 99m Tc-chlorambucil derivative as a potential tumor imaging agent.

Technetium-99m-based radiopharmaceuticals have been used widely as diagnostic agents in the nuclear medicine. Chlorambucil (CLB) as one typical alkylating drug exhibits excellent inhibition effects against many human malignancies. To develop and explore a novel potential imaging agent for early diagnosis of tumors, tricarbonyl technetium-99m and rhenium complexes on the basis of the tridentate ligand dipicolylamine (DPA) bound to the chlorambucil pharmacophore were designed and synthesized: 99m Tc-DPA-CLB (3) and Re-DPA-CLB (4). The high performance liquid chromatography analyses showed that the retention time of 3 and 4 was 13.5 and 13.6 minutes, respectively. Radiolabeling efficiency of the 99m Tc-DPA-CLB tracer was 97%, and the radiochemical purity was larger than 95% after 6 hours stored in phosphate buffered saline or human serum as observed by thin layer chromatography and high performance liquid chromatography. Biodistribution studies in a mouse model of breast cancer showed 99m Tc-DPA-CLB exhibited a favorable tumor affinity. The radiotracer cleared quickly in the first hour via hepatobiliary and renal routes of excretion, resulted in a very low background at 4 hours post injection (p.i.). It had moderate uptake ratios of tumor to blood and tumor to muscle. These results suggested 99m Tc-DPA-CLB might be a promising SPECT imaging agent for tumor diagnosis.

Platinum-zoledronate complex blocks gastric cancer cell proliferation by inducing cell cycle arrest and apoptosis.

A series of novel dinuclear platinum complexes based on the bisphosphonate ligands have been synthesized and characterized in our recent study. For the purpose of discovering the pharmacology and action mechanisms of this kind of compounds, the most potent compound [Pt(en)]2ZL was selected for systematic investigation. In the present study, the inhibition effect on the human gastric cancer cell lines SGC7901 and action mechanism of [Pt(en)]2ZL were investigated. The traditional 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2-tetrazolium bromide (MTT) assay and colony formation assay were carried out to study the effect of [Pt(en)]2ZL on the cell viability and proliferation capacity, respectively. The senescence-associated ß-galactosidase staining and immunofluorescence staining were also performed to assess the cell senescence and microtubule polymerization. Fluorescence staining and flow cytometry (FCM) were used to monitor the cell cycle distribution and apoptosis, and Western blot analysis was applied to examine the expression of several apoptosis-related proteins. The results demonstrated that [Pt(en)]2ZL exhibited remarkable cytotoxicity and anti-proliferative effects on the SGC7901 cells in a dose- and time-dependent manner, and it also induced cell senescence and abnormal microtubule assembly. The cell apoptosis and cell cycle arrest induced by [Pt(en)]2ZL were also observed with the fluorescence staining and FCM. The expressions of cell cycle regulators (p53, p21, cyclin D1, cyclin E, and cyclin-dependent kinase (CDK)2) and apoptosis-related proteins (Bcl-2, Bax, caspase-3, poly ADP ribose polymerase (PARP), and survivin) were regulated by the treatment of [Pt(en)]2ZL, resulting in the cell cycle arrest and apoptosis. Therefore, [Pt(en)]2ZL exerted anti-tumor effect on the gastric cancer via inducing cell cycle arrest at G1/S phase and apoptosis.

Preparation and Biological Evaluation of Two Novel Platinum(II) Complexes Based on the Ligands of Dipicolyamine Bisphosphonate Esters.

Two new platinum(II)-based complexes bearing a bone-targeting group were synthesized and characterized. They both have excellent affinity for hydroxyapatite (HA), which is abundant in human bone tissues. Their antitumor activities against five human cancer cell lines (U2OS, A549, HCT116, MDA-MB-231 and HepG2) were evaluated and compared with cisplatin (CDDP). Though the antitumor efficacies of new complexes are lower than that of CDDP, they show higher selectivity against the HepG2 hepatoma cell line than the L02 normal liver cell line. Morphology studies exhibited typical characteristics of cell apoptosis and the cell cycle distribution analysis indicated that the complexes can inhibit cancer cells by inducing cell cycle arrest at the G2/M phase, a similar mechanism of action to CDDP.

Synthesis and biological evaluation of novel platinum complexes of imidazolyl-containing bisphosphonates as potential anticancer agents.

Four novel platinum complexes, [Pt(en)]2ZL (1), [Pt(en)]2IPrBP (2), [Pt(en)]2MIBP (3) and [Pt(en)]2EIBP (4) [en = ethylenediamine; ZL = 1-hydroxy-3-(1H-imidazol-1-yl)ethane-1,1-diylbisphosphonic acid, commonly known as zoledronic acid; IPrBP = 1-hydroxy-3-(1H-imidazol-1-yl)propane-1,1-diylbisphosphonic acid; MIBP = 1-hydroxy-2-(2-methyl-1H-imidazol-1-yl)ethane-1,1-diylbisphosphonic acid; EIBP = 1-hydroxy-2-(2-ethyl-1H-imidazol-1-yl)ethane-1,1-diylbisphosphonic acid], were prepared and evaluated against five human cancer cell lines, including U2OS, A549, HCT116, MDA-MB-231 and HepG2. While exhibiting lower efficacy on the inhibition of cancer cell lines than cisplatin (CDDP), four complexes showed higher cytotoxicity than the corresponding ligands and relatively stronger cytotoxic effect on the hepatoma cell lines HepG2, and the complex 1 showed higher cytotoxicity than others on the whole. These complexes have better selectivity than the corresponding ligands in inhibiting hepatocarcinoma cells rather than normal liver cells, and the selective inhibitory effect of the complex 1 at the high concentration (100 µM) is better than that at the low concentration. Morphology studies exhibited typical characteristics of cell apoptosis and the cell cycle distribution analysis indicated that the complexes can inhibit cancer cells by inducing the cell cycle arrest at the G2/M phase, exhibiting a similar mechanism of action to CDDP. The binding interaction of complex with DNA has been explored by circular dichroism (CD) and UV-Vis absorption spectra, demonstrating these new complexes have moderate binding affinity for DNA.

Pharmacokinetic and imaging evaluation of (99m)Tc-HBIDP as a potential bone imaging agent.

Developing novel superior bone-seeking radiopharmaceutical for the detection of malignant bone lesions could further improve the diagnostic value of routine bone scanning and shorten the interval between injection and imaging. In order to further evaluate the bone imaging efficiency of (99m)Tc-HBIDP (1-hydroxy-2-(1-butyl-imidazol-2-yl)-ethane-1,1-diphosphonic acid), the pharmacokinetic in mice and single photon emission computed tomography (SPECT) bone scanning in rabbit for (99m)Tc-HBIDP was investigated. Kinetics of blood clearance showed that the distribution half-life (T(1/2a)) and elimination half-life (T(1/2 ß)) of (99m)Tc-HBIDP are 2.73 and 24.87 min, respectively. Excellent bone images can be obtained at 1 h post injection with SPECT bone scanning, which is clearer and quicker than (99m)Tc-ZL (zoledronate) and (99m)Tc-MDP (methylenediphosphonate). All results indicate that (99m)Tc-HBIDP holds great potential as a novel improved bone imaging agent.

Effect of dexmedetomidine infusion on postoperative sleep disturbances in women with breast cancer: A monocentric randomized-controlled double-blind trial.

BACKGROUND: Most women with breast cancer are prone to postoperative sleep disturbances (POSD). Little is known about the differences between sevoflurane and propofol combined with dexmedetomidine on POSD in the same context. We investigated the effect of intra-operative sevoflurane or propofol combined with intravenous dexmedetomidine on the incidence of POSD and postoperative sleep structures. METHODS: A monocentric, randomized-controlled, double-blind trial. Female patients undergoing radical surgery for breast cancer were randomly assigned to receive sevoflurane and placebo, sevoflurane and dexmedetomidine, propofol and placebo, or propofol and dexmedetomidine. Dexmedetomidine was administered at 1.0 µg kg-1 infusion 15 min before induction, then infused at 0.4 µg kg-1 h-1 until the surgical drain started to be placed. The primary outcome was the incidence of POSD within the postoperative first three days (defined as an Athens Insomnia Scale score ≥ 6 points on at least one day of postoperative first three days). The secondary outcome was the duration of sleep structures, collected from the Fitbit Charge 2® smart bracelet (Fitbit, Inc., San Francisco, CA, USA). RESULTS: There were 188 women analyzed with the modified intention-to-treat method. The incidences of POSD in the dexmedetomidine and placebo groups were similar (p = 0.649). In the sevoflurane sedation strategy, dexmedetomidine decreased nocturnal wakefulness on postoperative first day (p = 0.001). In the propofol sedation strategy, dexmedetomidine increased nocturnal deep sleep on postoperative first (p < 0.001) and third (p < 0.001) days. CONCLUSION: Intra-operative infusion of dexmedetomidine had no significant effect on POSD but decreased nocturnal wakefulness in the sevoflurane group and increased nocturnal deep sleep in the propofol group. TRIAL REGISTRATION: Registered at www.chictr.org.cn (ChiCTR2300070136).

Design, Synthesis, and Biological Evaluation of a Small-Molecule PET Agent for Imaging PD-L1 Expression.

Immunotherapy blocking programmed cell death protein 1/programmed death ligand 1 (PD-1/PD-L1) pathway has achieved great therapeutic effect in the clinic, but the overall response rate is not satisfactory. Early studies showed that response to treatment and overall survival could be positively related to PD-L1 expression in tumors. Therefore, accurate measurement of PD-L1 expression will help to screen cancer patients and improve the overall response rate. A small molecular positron emission tomography (PET) probe [18F]LP-F containing a biphenyl moiety was designed and synthesized for measurement of PD-L1 expression in tumors. The PET probe [18F]LP-F was obtained with a radiochemical yield of 12.72 ± 1.98%, a radiochemical purity of above 98% and molar activity of 18.8 GBq/µmol. [18F]LP-F had good stability in phosphate buffer saline (PBS) and mouse serum. In vitro assay indicated that [18F]LP-F showed moderate affinity to PD-L1. Micro-PET results showed that the tumor accumulation of [18F]LP-F in A375 tumor was inferior to that in A375-hPD-L1 tumor. All the results demonstrated that [18F]LP-F could specifically bind to PD-L1 and had a potential application in non-invasive evaluation of PD-L1 expression in tumors.

Development of a radiolabeled site-specific single-domain antibody positron emission tomography probe for monitoring PD-L1 expression in cancer.

Despite advances in immunotherapy for the treatment of cancers, not all patients can benefit from programmed cell death ligand 1 (PD-L1) immune checkpoint blockade therapy. Anti-PD-L1 therapeutic effects reportedly correlate with the PD-L1 expression level; hence, accurate detection of PD-L1 expression can guide immunotherapy to achieve better therapeutic effects. Therefore, based on the high affinity antibody Nb109, a new site-specifically radiolabeled tracer, 68Ga-NODA-cysteine, aspartic acid, and valine (CDV)-Nb109, was designed and synthesized to accurately monitor PD-L1 expression. The tracer 68Ga-NODA-CDV-Nb109 was obtained using a site-specific conjugation strategy with a radiochemical yield of about 95% and radiochemical purity of 97%. It showed high affinity for PD-L1 with a dissociation constant of 12.34 ± 1.65 nM. Both the cell uptake assay and positron emission tomography (PET) imaging revealed higher tracer uptake in PD-L1-positive A375-hPD-L1 and U87 tumor cells than in PD-L1-negative A375 tumor cells. Meanwhile, dynamic PET imaging of a NCI-H1299 xenograft indicated that doxorubicin could upregulate PD-L1 expression, allowing timely interventional immunotherapy. In conclusion, this tracer could sensitively and dynamically monitor changes in PD-L1 expression levels in different cancers and help screen patients who can benefit from anti-PD-L1 immunotherapy.