Transcriptional and Functional Analysis of CD1c+ Human Dendritic Cells Identifies a CD163+ Subset Priming CD8+CD103+ T Cells.

Dendritic cells (DCs) are antigen-presenting cells controlling T cell activation. In humans, the diversity, ontogeny, and functional capabilities of DC subsets are not fully understood. Here, we identified circulating CD88-CD1c+CD163+ DCs (called DC3s) as immediate precursors of inflammatory CD88-CD14+CD1c+CD163+FcεRI+ DCs. DC3s develop via a specific pathway activated by GM-CSF, independent of cDC-restricted (CDP) and monocyte-restricted (cMoP) progenitors. Like classical DCs but unlike monocytes, DC3s drove activation of naive T cells. In vitro, DC3s displayed a distinctive ability to prime CD8+ T cells expressing a tissue homing signature and the epithelial homing alpha-E integrin (CD103) through transforming growth factor ß (TGF-ß) signaling. In vivo, DC3s infiltrated luminal breast cancer primary tumors, and DC3 infiltration correlated positively with CD8+CD103+CD69+ tissue-resident memory T cells. Together, these findings define DC3s as a lineage of inflammatory DCs endowed with a strong potential to regulate tumor immunity.

Local auxin biosynthesis promotes shoot patterning and stem cell differentiation in Arabidopsis shoot apex.

The shoot apical meristem (SAM) of higher plants comprises distinct functional zones. The central zone (CZ) is located at the meristem summit and harbors pluripotent stem cells. Stem cells undergo cell division within the CZ and give rise to descendants, which enter the peripheral zone (PZ) and become recruited into lateral organs. Stem cell daughters that are pushed underneath the CZ form rib meristem (RM). To unravel the mechanism of meristem development, it is essential to know how stem cells adopt distinct cell fates in the SAM. Here, we show that meristem patterning and floral organ primordia formation, besides auxin transport, are regulated by auxin biosynthesis mediated by two closely related genes of the TRYPTOPHAN AMINOTRANSFERASE family. In Arabidopsis SAM, TAA1 and TAR2 played a role in maintaining auxin responses and the identity of PZ cell types. In the absence of auxin biosynthesis and transport, the expression pattern of the marker genes linked to the patterning of the SAM is perturbed. Our results prove that local auxin biosynthesis, in concert with transport, controls the patterning of the SAM into the CZ, PZ and RM.

Resident memory T cells in nonlesional skin and healed lesions of patients with chronic inflammatory diseases: Appearances can be deceptive.

Tissue-resident memory T (TRM) cells serve as a first line of defense in peripheral tissues to protect the organism against foreign pathogens. However, autoreactive TRM cells are increasingly implicated in autoimmunity, as evidenced in chronic autoimmune and inflammatory skin conditions. This highlights the need to characterize their phenotype and understand their role for the purpose of targeting them specifically without affecting local immunity. To date, the investigation of TRM cells in human skin diseases has focused mainly on lesional tissues of patients. Accumulating evidence suggests that self-reactive TRM cells are still present in clinically healed lesions of patients and play a role in disease flares, but TRM cells also populate skin that is apparently normal. This review discusses the ontogeny of TRM cells in the skin as well as recent insights regarding the presence of self-reactive TRM cells in both clinically healed skin and nonlesional skin of patients with autoimmune and inflammatory skin conditions, with a particular focus on psoriasis, atopic dermatitis, and vitiligo.

CRISPR-Cas3 and type I restriction-modification team up against blaKPC-IncF plasmid transfer in Klebsiella pneumoniae.

OBJECTIVE: We explored whether the Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas and restriction-modification (R-M) systems are compatible and act together to resist plasmid attacks. METHODS: 932 global whole-genome sequences from GenBank, and 459 K. pneumoniae isolates from six provinces of China, were collected to investigate the co-distribution of CRISPR-Cas, R-M systems, and blaKPC plasmid. Conjugation and transformation assays were applied to explore the anti-plasmid function of CRISPR and R-M systems. RESULTS: We found a significant inverse correlation between the presence of CRISPR and R-M systems and blaKPC plasmids in K. pneumoniae, especially when both systems cohabited in one host. The multiple matched recognition sequences of both systems in blaKPC-IncF plasmids (97%) revealed that they were good targets for both systems. Furthermore, the results of conjugation assay demonstrated that CRISPR-Cas and R-M systems in K. pneumoniae could effectively hinder blaKPC plasmid invasion. Notably, CRISPR-Cas and R-M worked together to confer a 4-log reduction in the acquisition of blaKPC plasmid in conjugative events, exhibiting robust synergistic anti-plasmid immunity. CONCLUSIONS: Our results indicate the synergistic role of CRISPR and R-M in regulating horizontal gene transfer in K. pneumoniae and rationalize the development of antimicrobial strategies that capitalize on the immunocompromised status of KPC-KP.

Diagnostic accuracy of fully hybrid [68Ga]Ga-PSMA-11 PET/MRI and [68Ga]Ga-RM2 PET/MRI in patients with biochemically recurrent prostate cancer: a prospective single-center phase II clinical trial.

PURPOSE: To compare the diagnostic accuracy and detection rates of PET/MRI with [68Ga]Ga-PSMA-11 and [68Ga]Ga-M2 in patients with biochemical recurrence of prostate cancer (PCa). METHODS: Sixty patients were enrolled in this prospective single-center phase II clinical trial from June 2020 to October 2022. Forty-four/60 completed all study examinations and were available at follow-up (median: 22.8 months, range: 6-31.5 months). Two nuclear medicine physicians analyzed PET images and two radiologists interpreted MRI; images were then re-examined to produce an integrated PET/MRI report for both [68Ga]Ga-PSMA-11 and [68Ga]Ga-RM2 examinations. A composite reference standard including histological specimens, response to treatment, and conventional imaging gathered during follow-up was used to validate imaging findings. Detection rates, accuracy, sensitivity, specificity, positive, and negative predictive value were assessed. McNemar's test was used to compare sensitivity and specificity on a per-patient base and detection rate on a per-region base. Prostate bed, locoregional lymph nodes, non-skeletal distant metastases, and bone metastases were considered. p-value significance was defined below the 0.05 level after correction for multiple testing. RESULTS: Patients' median age was 69.8 years (interquartile range (IQR): 61.8-75.1) and median PSA level at time of imaging was 0.53 ng/mL (IQR: 0.33-2.04). During follow-up, evidence of recurrence was observed in 31/44 patients. Combining MRI with [68Ga]Ga-PSMA-11 PET and [68Ga]Ga-RM2 PET resulted in sensitivity = 100% and 93.5% and specificity of 69.2% and 69.2%, respectively. When considering the individual imaging modalities, [68Ga]Ga-RM2 PET showed lower sensitivity compared to [68Ga]Ga-PSMA-11 PET and MRI (61.3% vs 83.9% and 87.1%, p = 0.046 and 0.043, respectively), while specificity was comparable among the imaging modalities (100% vs 84.6% and 69.2%, p = 0.479 and 0.134, respectively). CONCLUSION: This study brings further evidence on the utility of fully hybrid PET/MRI for disease characterization in patients with biochemically recurrent PCa. Imaging with [68Ga]Ga-PSMA-11 PET showed high sensitivity, while the utility of [68Ga]Ga-RM2 PET in absence of a simultaneous whole-body/multiparametric MRI remains to be determined.

Synthesis and Evaluation of 68Ga- and 177Lu-Labeled [Pro14]bombesin(8-14) Derivatives for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer.

The gastrin-releasing peptide receptor (GRPR) is overexpressed in a variety of cancers and represents a promising target for diagnosis and therapy. However, the extremely high accumulation in the pancreas observed for most of the clinically evaluated GRPR-targeted radiopharmaceuticals could limit their applications. In this study, we synthesized one GRPR antagonist (ProBOMB5) and two GRPR agonists (LW02056 and LW02057) by replacing the 4-thiazolidinecarboxylic acid (Thz14) residue in our previously reported GRPR-targeted tracers with Pro14. The 68Ga and 177Lu labeling were conducted in HEPES (2 M, pH 5.0) buffer and acetate (0.1 M, pH 4.5) buffer, respectively, and the radiolabeled products were obtained in a 24-57% decay-corrected radiochemical yield and >92% radiochemical purity. The binding affinities (Ki) of Ga-ProBOMB5, Ga-LW02056, Ga-LW02057, and Lu-ProBOMB5 were measured via in vitro competition binding assays and were 12.2 ± 1.89, 14.7 ± 4.81, 13.8 ± 2.24, and 13.6 ± 0.25 nM, respectively. The PET imaging and ex vivo biodistribution studies were conducted in PC-3 tumor-bearing mice at 1 h post injection. [68Ga]Ga-ProBOMB5, [68Ga]Ga-LW02056, and [68Ga]Ga-LW02057 enabled clear tumor visualization in PET images. The tumor uptake values of [68Ga]Ga-ProBOMB5, [68Ga]Ga-LW02056, and [68Ga]Ga-LW02057 were 12.4 ± 1.35, 8.93 ± 1.96, and 7.64 ± 0.55%ID/g, respectively, and their average pancreas uptake values were minimal (0.60-1.37%ID/g). Longitudinal SPECT imaging and ex vivo biodistribution studies were also conducted for [177Lu]Lu-ProBOMB5 and clinically validated [177Lu]Lu-RM2. Despite comparable tumor uptake at 1 h post injection ([177Lu]Lu-ProBOMB5:8.09 ± 1.70%ID/g; [177Lu]Lu-RM2:7.73 ± 0.96%ID/g), a faster clearance from PC-3 tumor xenografts was observed for [177Lu]Lu-ProBOMB5, leading to a lower radiation-absorbed dose delivered to tumors. Our data demonstrate that [68Ga]Ga-ProBOMB5 is a promising tracer for clinical translation for detecting GRPR-expressing tumor lesions. However, further optimizations are needed for [177Lu]Lu-ProBOMB5 to prolong tumor retention for therapeutic applications.

Emerging monoclonal antibody therapy for head and neck squamous cell carcinoma.

INTRODUCTION: The incidence of head and neck squamous cell carcinoma (HNSCC) is increasing, particularly among younger populations. It is projected that the number of new cases will increase by almost 50% by 2040, with market revenues expected to triple in the same period. Despite the recent introduction of immune checkpoint inhibitors (ICIs) into the therapeutic armamentarium, the vast majority of patients with recurrent and/or metastatic (R/M) HNSCC fail to derive durable benefits from systemic therapy. AREAS COVERED: This article aims to review the multiple monoclonal antibodies (mAbs) regimens currently under development, targeting various growth factors, immune checkpoints, immune costimulatory receptors, and more. EXPERT OPINION: So far, the combination of anti-EGFR and ICI appears to be the most promising, especially in HPV-negative patients. It will be interesting to confirm whether the arrival of antibody-drug conjugates and bispecific mAb can surpass the efficacy of anti-EGFR, as they are also being tested in combination with ICI. Furthermore, we believe that immune costimulatory agonists and various ICIs combination are worth monitoring, despite some initial setbacks.

A Whole-Process Visible Strategy for the Preparation of Rhizomucor miehei Lipase with Escherichia coli Secretion Expression System and the Immobilization.

BACKGROUND: Rhizomucor miehei (RM) lipase is a regioselective lipase widely used in food, pharmaceutical and biofuel industries. However, the high cost and low purity of the commercial RM lipase limit its industrial applications. Therefore, it is necessary to develop cost-effective strategies for large-scale preparation of this lipase. The present study explored the high-level expression of RM lipase using superfolder green fluorescent protein (sfGFP)-mediated Escherichia coli secretion system. RESULTS: The sfGFP(-15) mutant was fused to the C-terminus of RM lipase to mediate its secretion expression. The yield of the fusion protein reached approximately 5.1 g/L with high-density fermentation in 5-L fermentors. Unlike conventional secretion expression methods, only a small portion of the target protein was secreted into the cell culture while majority of the fusion protein was still remained in the cytoplasm. However, in contrast to intracellular expression, the target protein in the cytoplasm could be transported efficiently to the supernatant through a simple washing step with equal volume of phosphate saline (PBS), without causing cell disruption. Hence, the approach facilitated the downstream purification step of the recombinant RM lipase. Moreover, contamination or decline of the engineered strain and degradation or deactivation of the target enzyme can be detected efficiently because they exhibited bright green fluorescence. Next, the target protein was immobilized with anion-exchange and macropore resins. Diethylaminoethyl sepharose (DEAE), a weak-basic anion-exchange resin, exhibited the highest bind capacity but inhibited the activity of RM lipase dramatically. On the contrary, RM lipase fixed with macropore resin D101 demonstrated the highest specific activity. Although immobilization with D101 didn't improve the activity of the enzyme, the thermostability of the immobilized enzyme elevated significantly. The immobilized RM lipase retained approximately 90% of its activity after 3-h incubation at 80 °C. Therefore, D101 was chosen as the supporting material of the target protein. CONCLUSION: The present study established a highly efficient strategy for large-scale preparation of RM lipase. This innovative technique not only provides high-purity RM lipase at a low cost but also has great potential as a platform for the preparation of lipases in the future.

Head and neck cancer patient journey's health literacy: a multidisciplinary team perspective. VOICE study.

PURPOSE: Health literacy is a current Public Health priority in Portugal. The participation of well-informed patients in their care and shared decision making are essential, especially in chronic aggressive and debilitating pathologies such as recurrent or metastatic (R/M) Head and Neck Squamous Cell Carcinoma (HNSCC). AIMS: This study aimed to characterize R/M HNSCC patients' and caregivers' information needs identified by healthcare professionals (HCPs). METHODS: Two online Focus Groups, one with only medical doctors and the other with other HCPs involved in the treatment of R/M HNSCC patients, were conducted, using a modified Metaplan, Lean or adapted PDCA methodology. The discussions were audio recorded in full and content analysis was performed using ATLAS.ti qualitative data analysis software. RESULTS: Topics addressed were diagnosis, treatment, quality of life, and global evaluation. In general, all experts agreed that only essential information should be cautiously given, according to patients' and caregivers' wishes. It was consensual that patients are given the necessary information to adhere to treatment. Two main barriers were identified: one barrier was associated with verbal communication due to the lack of health literacy of these patients, and the other barrier regarded healthcare access. It was also considered important to remind patients of the daily and social activities that they could and should maintain, as well as providing sufficient social resources and problem-solving training to caregivers. CONCLUSIONS: This qualitative study highlights the complexity of R/M HNSCC patients' care. Immediate availability of psychologists and psychiatrists should be implemented in all centers that treat HNSCC patients. The differences found between the physicians' Focus Group and other HCPs' Focus Group in some of the addressed topics emphasize the importance of a multidisciplinary and holistic approach, in a biomedical model integrated with a biopsychosocial model.

Memory CD8+ T cell responses to cancer.

Long-lived memory CD8+ T cells play important roles in tumor immunity. Studies over the past two decades have identified four subsets of memory CD8+ T cells - central, effector, stem-like, and tissue resident memory - that either circulate through blood, lymphoid and peripheral organs, or reside in tissues where cancers develop. In this article, we will review studies from both pre-clinical mouse models and human patients to summarize the phenotype, distribution and unique features of each memory subset, and highlight specific roles of each subset in anti-tumor immunity. Moreover, we will discuss how stem-cell like and resident memory CD8+ T cell subsets relate to exhausted tumor-infiltrating lymphocytes (TIL) populations. These studies reveal how memory CD8+ T cell subsets together orchestrate durable immunity to cancer.

Characterization of a Novel N4-Methylcytosine Restriction-Modification System in Deinococcus radiodurans.

Deinococcus radiodurans is an extremophilic microorganism that possesses a unique DNA damage repair system, conferring a strong resistance to radiation, desiccation, oxidative stress, and chemical damage. Recently, we discovered that D. radiodurans possesses an N4-methylation (m4C) methyltransferase called M.DraR1, which recognizes the 5'-CCGCGG-3' sequence and methylates the second cytosine. Here, we revealed its cognate restriction endonuclease R.DraR1 and recognized that it is the only endonuclease specially for non-4C-methylated 5'-CCGCGG-3' sequence so far. We designated the particular m4C R.DraR1-M.DraR1 as the DraI R-M system. Bioinformatics searches displayed the rarity of the DraI R-M homologous system. Meanwhile, recombination and transformation efficiency experiments demonstrated the important role of the DraI R-M system in response to oxidative stress. In addition, in vitro activity experiments showed that R.DraR1 could exceptionally cleave DNA substrates with a m5C-methlated 5'-CCGCGG-3' sequence instead of its routine activity, suggesting that this particular R-M component possesses a broader substrate choice. Furthermore, an imbalance of the DraI R-M system led to cell death through regulating genes involved in the maintenance of cell survival such as genome stability, transporter, and energy production. Thus, our research revealed a novel m4C R-M system that plays key roles in maintaining cell viability and defending foreign DNA in D. radiodurans.

Synthesis and Physicochemical Characterization of Gelatine-Based Biodegradable Aerogel-like Composites as Possible Scaffolds for Regenerative Medicine.

Regenerative medicine is an interdisciplinary field aiming at restoring pathologically damaged tissues and whole organs by cell transplantation in combination with proper supporting scaffolds. Gelatine-based ones are very attractive due to their biocompatibility, rapid biodegradability, and lack of immunogenicity. Gelatine-based composite hydrogels, containing strengthening agents to improve their modest mechanical properties, have been demonstrated to act as extracellular matrices (ECMs), thus playing a critical role in "organ manufacturing". Inspired by the lysyl oxidase (LO)-mediated process of crosslinking, which occurs in nature to reinforce collagen, we have recently developed a versatile protocol to crosslink gelatine B (Gel B) in the presence or absence of LO, using properly synthesized polystyrene- and polyacrylic-based copolymers containing the amine or aldehyde groups needed for crosslinking reactions. Here, following the developed protocol with slight modifications, we have successfully crosslinked Gel B in different conditions, obtaining eight out of nine compounds in high yield (57-99%). The determined crosslinking degree percentage (CP%) evidenced a high CP% for compounds obtained in presence of LO and using the styrenic amine-containing (CP5/DMAA) and acrylic aldehyde-containing (CPMA/DMAA) copolymers as crosslinking agents. ATR-FTIR analyses confirmed the chemical structure of all compounds, while optical microscopy demonstrated cavernous, crater-like, and labyrinth-like morphologies and cavities with a size in the range 15-261 µm. An apparent density in the range 0.10-0.45 g/cm3 confirmed the aerogel-like structure of most samples. Although the best biodegradation profile was observed for the sample obtained using 10% CP5/DMAA (M3), high swelling and absorption properties, high porosity, and good biodegradation profiles were also observed for samples obtained using the 5-10% CP5/DMAA (M4, 5, 6) and 20% CPMA/DMAA (M9) copolymers. Collectively, in this work of synthesis and physicochemical characterization, new aerogel-like composites have been developed and, based on their characteristics, which fit well within the requirements for TE, five candidates (M3, M4, M5, M6, and M9) suitable for future biological experiments on cell adhesion, infiltration and proliferation, to confirm their effective functioning, have been identified.

Short-Finned Pilot Whale Strandings Associated with Pilot Whale Morbillivirus, Brazil.

Cetacean morbillivirus (CeMV) causes illness and death in cetaceans worldwide; the CeMV strains circulating in the Southern Hemisphere are poorly known. We detected a pilot whale CeMV strain in 3 short-finned pilot whales (Globicephala macrorhynchus) stranded in Brazil during July-October 2020. Our results confirm this virus circulates in this species.

A new histone deacetylase inhibitor remodels the tumor microenvironment by deletion of polymorphonuclear myeloid-derived suppressor cells and sensitizes prostate cancer to immunotherapy.

BACKGROUND: Prostate cancer (PCa) is the most common malignancy diagnosed in men. Immune checkpoint blockade (ICB) alone showed disappointing results in PCa. It is partly due to the formation of immunosuppressive tumor microenvironment (TME) could not be reversed effectively by ICB alone. METHODS: We used PCa cell lines to evaluate the combined effects of CN133 and anti-PD-1 in the subcutaneous and osseous PCa mice models, as well as the underlying mechanisms. RESULTS: We found that CN133 could reduce the infiltration of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), and CN133 combination with anti-PD-1 could augment antitumor effects in the subcutaneous PCa of allograft models. However, anti-PD-1 combination with CN133 failed to elicit an anti-tumor response to the bone metastatic PCa mice. Mechanistically, CN133 could inhibit the infiltration of PMN-MDSCs in the TME of soft tissues by downregulation gene expression of PMN-MDSC recruitment but not change the gene expression involved in PMN-MDSC activation in the CN133 and anti-PD-1 co-treatment group relative to the anti-PD-1 alone in the bone metastatic mice model. CONCLUSIONS: Taken together, our work firstly demonstrated that combination of CN133 with anti-PD-1 therapy may increase the therapeutic efficacy to PCa by reactivation of the positive immune microenvironment in the TME of soft tissue PCa.

The Multifaceted Role of Homologous Recombination in a Fastidious Bacterial Plant Pathogen.

Homologous recombination plays a key function in the evolution of bacterial genomes. Within Xylella fastidiosa, an emerging plant pathogen with increasing host and geographic ranges, it has been suggested that homologous recombination facilitates host switching, speciation, and the development of virulence. We used 340 whole-genome sequences to study the relationship between inter- and intrasubspecific homologous recombination, random mutation, and natural selection across individual X. fastidiosa genes. Individual gene orthologs were identified and aligned, and a maximum likelihood (ML) gene tree was generated. Each gene alignment and tree pair were then used to calculate gene-wide and branch-specific r/m values (relative effect of recombination to mutation), gene-wide and branch-site nonsynonymous over synonymous substitution rates (dN/dS values; episodic selection), and branch length (as a proxy for mutation rate). The relationships between these variables were evaluated at the global level (i.e., for all genes among and within a subspecies), among specific functional classes (i.e., COGs), and between pangenome components (i.e., accessory versus core genes). Our analysis showed that r/m varied widely among genes as well as across X. fastidiosa subspecies. While r/m and dN/dS values were positively correlated in some instances (e.g., core genes in X. fastidiosa subsp. fastidiosa and both core and accessory genes in X. fastidiosa subsp. multiplex), low correlation coefficients suggested no clear biological significance. Overall, our results indicate that, in addition to its adaptive role in certain genes, homologous recombination acts as a homogenizing and a neutral force across phylogenetic clades, gene functional groups, and pangenome components. IMPORTANCE There is ample evidence that homologous recombination occurs frequently in the economically important plant pathogen Xylella fastidiosa. Homologous recombination has been known to occur among sympatric subspecies and is associated with host-switching events and virulence-linked genes. As a consequence, is it generally assumed that recombinant events in X. fastidiosa are adaptive. This mindset influences expectations of how homologous recombination acts as an evolutionary force as well as how management strategies for X. fastidiosa diseases are determined. Yet, homologous recombination plays roles beyond that of a source for diversification and adaptation. Homologous recombination can act as a DNA repair mechanism, as a means to facilitate nucleotide compositional change, as a homogenization mechanism within populations, or even as a neutral force. Here, we provide a first assessment of long-held beliefs regarding the general role of recombination in adaptation for X. fastidiosa. We evaluate gene-specific variations in homologous recombination rate across three X. fastidiosa subspecies and its relationship to other evolutionary forces (e.g., natural selection, mutation, etc.). These data were used to assess the role of homologous recombination in X. fastidiosa evolution.

Side-by-side comparison of the two widely studied GRPR radiotracers, radiolabeled NeoB and RM2, in a preclinical setting.

INTRODUCTION: NeoB and RM2 are the most investigated gastrin-releasing peptide receptor (GRPR)-targeting radiotracers in preclinical and clinical studies. Therefore, an extensive side-by-side comparison of the two radiotracers is valuable to demonstrate whether one has advantages over the other. Accordingly, this study aims to compare the in vitro and in vivo characteristics of radiolabeled NeoB and RM2 to guide future clinical studies. METHOD: The stability of the radiolabeled GRPR analogs was determined in phosphate buffered saline (PBS), and commercially available mouse and human serum. Target affinity was determined by incubating human prostate cancer PC-3 cells with [177Lu]Lu-NeoB or [177Lu]Lu-RM2, + / - increasing concentrations of unlabeled NeoB, RM2, or Tyr4-bombesin (BBN). To determine uptake and specificity cells were incubated with [177Lu]Lu-NeoB or [177Lu]Lu-RM2 + / - Tyr4-BBN. Moreover, in vivo studies were performed to determine biodistribution and pharmacokinetics. Finally, radiotracer binding to various GRPR-expressing human cancer tissues was investigated. RESULTS: Both radiotracers demonstrated high stability in PBS and human serum, but stability in mouse serum decreased substantially over time. Moreover, both radiotracers demonstrated high GRPR affinity and specificity, but a higher uptake of [177Lu]Lu-NeoB was observed in in vitro studies. In vivo, no difference in tumor uptake was seen. The most prominent difference in uptake in physiological organs was observed in the GRPR-expressing pancreas; [177Lu]Lu-RM2 had less pancreatic uptake and a shorter pancreatic half-life than [177Lu]Lu-NeoB. Furthermore, [177Lu]Lu-RM2 presented with a lower tumor-to-kidney ratio, while the tumor-to-blood ratio was lower for [177Lu]Lu-NeoB. The autoradiography studies revealed higher binding of radiolabeled NeoB to all human tumor tissues. CONCLUSION: Based on these findings, we conclude that the in vivo tumor-targeting capability of radiolabeled NeoB and RM2 is similar. Additional studies are needed to determine whether the differences observed in physiological organ uptakes, i.e., the pancreas, kidneys, and blood, result in relevant differences in organ absorbed doses when the radiotracers are applied for therapeutic purposes.

Modified PROMISE criteria for standardized interpretation of gastrin-releasing peptide receptor (GRPR)-targeted PET.

PURPOSE: There are image interpretation criteria to standardize reporting prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET). As up to 10% of prostate cancer (PC) do not express PSMA, other targets such as gastrin-releasing peptide receptor (GRPR) are evaluated. Research on GRPR-targeted imaging has been slowly increasing in usage at staging and biochemical recurrence (BCR) of PC. We therefore propose a modification of the Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) criteria (mPROMISE) for GRPR-targeted PET. METHODS: [68 Ga]Ga-RM2 PET data from initially prospective studies performed at our institution were retrospectively reviewed: 44 patients were imaged for staging and 100 patients for BCR PC. Two nuclear medicine physicians independently evaluated PET according to the mPROMISE criteria. A third expert reader served as standard reference. Interreader reliability was computed for GRPR expression, prostate bed (T), lymph node (N), skeleton (Mb), organ (Mc) metastases, and final judgment of the scan. RESULTS: The interrater reliability for GRPR PET at staging was moderate for GRPR expression (0.59; 95% confidence interval [CI] 0.40, 0.78), substantial for T-stage (0.78; 95% CI 0.63, 0.94), and almost perfect for N-stage (0.97; 95% CI 0.92, 1.00) and final judgment (0.92; 95% CI 0.82, 1.00). The interreader agreement at BCR showed substantial agreement for GRPR expression (0.70; 95% CI 0.59, 0.81) and final judgment (0.65; 95% CI 0.53, 0.78), while almost perfect agreement was seen across the major categories (T, N, Mb, Mc). Acceptable performance of the mPROMISE criteria was found for all subsets when compared to the standard reference. CONCLUSION: Interpreting GRPR-targeted PET using the mPROMISE criteria showed its reliability with substantial or almost perfect interrater agreement across all major categories. The proposed modification of the PROMISE criteria will aid clinicians in decreasing the level of uncertainty, and clinical trials to achieve uniform evaluation, reporting, and comparability of GRPR-targeted PET. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT03113617 and NCT02624518.

A prospective comparative study of [68Ga]Ga-RM26 and [68Ga]Ga-PSMA-617 PET/CT imaging in suspicious prostate cancer.

PURPOSE: Prostate-specific membrane antigen (PSMA)-based PET/CT imaging has limitations in the diagnosis of prostate cancer (PCa). We recruited 207 participants with suspicious PCa to perform PET/CT imaging with radiolabeled gastrin-releasing peptide receptor (GRPR) antagonist, [68Ga]Ga-RM26, and compare with [68Ga]Ga-PSMA-617 and histopathology. METHODS: Every participant with suspicious PCa was scanned with both [68Ga]Ga-RM26 and [68Ga]Ga-PSMA-617 PET/CT. PET/CT imaging was compared using pathologic specimens as a reference standard. RESULTS: Of the 207 participants analyzed, 125 had cancer, and 82 were diagnosed with benign prostatic hyperplasia (BPH). The sensitivity and specificity of [68Ga]Ga-RM26 and [68Ga]Ga-PSMA-617 PET/CT imaging differed significantly for detecting clinically significant PCa. The area under the ROC curve (AUC) was 0.54 for [68Ga]Ga-RM26 PET/CT and 0.91 for [68Ga]Ga-PSMA-617 PET/CT in detecting PCa. For clinically significant PCa imaging, the AUCs were 0.51 vs. 0.93, respectively. [68Ga]Ga-RM26 PET/CT imaging had higher sensitivity for PCa with Gleason score (GS) = 6 (p = 0.03) than [68Ga]Ga-PSMA-617 PET/CT but poor specificity (20.73%). In the group with PSA < 10 ng/mL, the sensitivity, specificity, and AUC of [68Ga]Ga-RM26 PET/CT were lower than [68Ga]Ga-PSMA-617 PET/CT (60.00% vs. 80.30%, p = 0.12, 23.26% vs. 88.37%, p = 0.000, and 0.524 vs. 0.822, p = 0.000, respectively). [68Ga]Ga-RM26 PET/CT exhibited significantly higher SUVmax in specimens with GS = 6 (p = 0.04) and in the low-risk group (p = 0.01), and its uptake did not increase with PSA level, GS, or clinical stage. CONCLUSION: This prospective study provided evidence for the superior accuracy of [68Ga]Ga-PSMA-617 PET/CT over [68Ga]Ga-RM26 PET/CT in detecting more clinically significant PCa. [68Ga]Ga-RM26 PET/CT showed an advantage for imaging low-risk PCa.

Revisiting the TCNQF4 0/1-/2- Catalysis Mechanism for the [Fe(CN)6 ]3-/4- -S2 O3 2- /S4 O6 2- Redox Reaction.

Published data suggest that sparingly soluble metal complexes of TCNQF n 1 - ${{\rm{TCNQF}}_{\rm{n}}^{{\rm{1 - }}} }$ , where n=0, 1, 2, 4, can act as heterogeneous catalysts for the kinetically very slow [ Fe ( CN ) 6 ]​ 3 - / 4 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{3 - /4 - }}} }$ - S 2 O 3 2 - ${{\rm{S}}_{\rm{2}} {\rm{O}}_{\rm{3}}^{{\rm{2 - }}} }$ / S 4 O 6 2 - ${{\rm{S}}_{\rm{4}} {\rm{O}}_{\rm{6}}^{{\rm{2 - }}} }$ reaction in aqueous solution. This study shows that the coordination polymer CuTCNQF 4 ${{\rm{CuTCNQF}}_{\rm{4}} }$ , participates as a homogeneous catalyst via an extremely small concentration of dissolved TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ . This finding suggests that the generally accepted mechanism of catalysis by TCNQF 4 ${{\rm{TCNQF}}_{\rm{4}} }$ based solids needs to be revisited to ascertain the role of homogeneous pathways. In the present study, UV-visible spectrophotometry was used to examine the catalysis of the aqueous redox reaction of [ Fe ( CN ) 6 ]​ 3 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{3 - }}} }$ (1.0 mM) with S 2 O 3 2 - ${{\rm{S}}_{\rm{2}} {\rm{O}}_{\rm{3}}^{{\rm{2 - }}} }$ (100 mM) in the presence of (i) a precursor catalyst, TCNQF 4 0 ${{\rm{TCNQF}}_{\rm{4}}^{\rm{0}} }$ ; (ii) the catalyst, TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ , as the water soluble Li+ salt; and (iii) CuTCNQF 4 ${{\rm{CuTCNQF}}_{\rm{4}} }$ . A homogeneous reaction scheme that utilises the TCNQF 4 1 - / 2 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - /2 - }}} }$ couple is provided. In the case of TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ derived from highly soluble LiTCNQF 4 ${{\rm{LiTCNQF}}_{\rm{4}} }$ , quantitative conversion of 1.0 mM S 2 O 3 2 - ${{\rm{S}}_{\rm{2}} {\rm{O}}_{\rm{3}}^{{\rm{2 - }}} }$ to 0.50 mM S 4 O 6 2 - ${{\rm{S}}_{\rm{4}} {\rm{O}}_{\rm{6}}^{{\rm{2 - }}} }$ occurs with complete reduction of [ Fe ( CN ) 6 ]​ 3 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{3 - }}} }$ to [ Fe ( CN ) 6 ]​ 4 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{4 - }}} }$ being rapidly accelerated by sub-micomolar concentrations of TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ . TCNQF 4 2 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{2 - }}} }$ generated in the catalytic cycle, reacts with [ Fe ( CN ) 6 ]​ 3 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{3 - }}} }$ to reform TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ and produce [ Fe ( CN ) 6 ]​ 4 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{4 - }}} }$ . Along with the rapid catalytic reaction, the sluggish competing reaction between TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ and S 2 O 3 2 - ${{\rm{S}}_{\rm{2}} {\rm{O}}_{\rm{3}}^{{\rm{2 - }}} }$ occurs to give TCNQF 4 2 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{2 - }}} }$ , which is protonated to HTCNQF 4 1 - ${{\rm{\;HTCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ , along with a trace amount of S 4 O 6 2 - ${{\rm{S}}_{\rm{4}} {\rm{O}}_{\rm{6}}^{{\rm{2 - }}} }$ . On addition of the precursor catalyst, TCNQF 4 0 ${{\rm{TCNQF}}_{\rm{4}}^{\rm{0}} }$ , rapid reduction with S 2 O 3 2 - ${{\rm{S}}_{\rm{2}} {\rm{O}}_{\rm{3}}^{{\rm{2 - }}} }$ occurs to form TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ - the active catalyst. CuTCNQF 4 ${{\rm{CuTCNQF}}_{\rm{4}} }$ added to water is shown to be sufficiently soluble to provide adequate TCNQF 4 1 - ${{\rm{TCNQF}}_{\rm{4}}^{{\rm{1 - }}} }$ to act as the catalyst for the [ Fe ( CN ) 6 ]​ 3 - / 4 - ${{\rm{[Fe(CN)}}_{\rm{6}} {\rm{]}}^{{\rm{3 - /4 - }}} }$ - S 2 O 3 2 - ${{\rm{S}}_{\rm{2}} {\rm{O}}_{\rm{3}}^{{\rm{2 - }}} }$ / S 4 O 6 2 - ${{\rm{S}}_{\rm{4}} {\rm{O}}_{\rm{6}}^{{\rm{2 - }}} }$ reaction.

Value of 68Ga-labeled bombesin antagonist (RM2) in the detection of primary prostate cancer comparing with [18F]fluoromethylcholine PET-CT and multiparametric MRI-a phase I/II study.

OBJECTIVES: The bombesin derivative RM2 is a GRPr antagonist with strong binding affinity to prostate cancer (PCa). In this study, the impact of [68Ga]Ga-RM2 positron emission tomography-computed tomography (PET-CT) for the detection of primary PCa was compared with that of [18F]FCH PET-CT and multiparametric magnetic resonance imaging (mpMRI). METHODS: This phase I/II study was conducted in 30 biopsy-positive PCa subjects. The patients were stratified into high (10 patients), intermediate (10 patients), and low risk (10 patients) for extraglandular metastases as defined by National Comprehensive Cancer Network (NCCN) criteria (NCCN Clinical Practice Guidelines in Oncology, 2016). The prostate gland was classified in 12 anatomic segments for data analysis of the imaging modalities as well as histopathologic findings. The segment with the highest radiotracer uptake was defined as the "index lesion." All cases were scheduled to undergo prostatectomy with pelvic lymph node (LN) dissection in intermediate- and high-risk patients. Intraprostatic and pelvic nodal [68Ga]Ga-RM2 and [18F]FCH PET-CT findings were correlated with mpMRI and histopathologic results. RESULTS: Of the 312 analyzed regions, 120 regions (4 to 8 lesions per patient) showed abnormal findings in the prostate gland. In a region-based analysis, overall sensitivity and specificity of [68Ga]Ga-RM2 PET-CT in the detection of primary tumor were 74% and 90%, respectively, while it was 60% and 80% for [18F]FCH PET-CT and 72% and 89% for mpMRI. Although the overall sensitivity of [68Ga]Ga-RM2 PET-CT was higher compared to that of [18F]FCH PET-CT and mpMRI, the statistical analysis showed only significant difference between [68Ga]Ga-RM2 PET-CT and [18F]FCH PET-CT in the intermediate-risk group (p = 0.01) and [68Ga]Ga-RM2 PET-CT and mpMRT in the high-risk group (p = 0.03). In the lesion-based analysis, there was no significant difference between SUVmax of [68Ga]Ga-RM2 and [18F]FCH PET-CT in the intraprostatic malignant lesions ([68Ga]Ga-RM2: mean SUVmax: 5.98 ± 4.13, median: 4.75; [18F]FCH: mean SUVmax: 6.08 ± 2.74, median: 5.5; p = 0.13). CONCLUSIONS: [68Ga]Ga-RM2 showed promising PET tracer for the detection of intraprostatic PCa in a cohort of patients with different risk stratifications. However, significant differences were only found between [68Ga]Ga-RM2 PET-CT and [18F]FCH PET-CT in the intermediate-risk group and [68Ga]Ga-RM2 PET-CT and mpMRT in the high-risk group. In addition, GRP-R-based imaging seems to play a complementary role to choline-based imaging for full characterization of PCa extent and biopsy guidance in low- and intermediate-metastatic-risk PCa patients and has the potential to discriminate them from those at higher risks. KEY POINTS: • [68Ga]Ga-RM2 is a promising PET tracer with a high detection rate for intraprostatic PCa especially in intermediate-risk prostate cancer patients. • GRPr-based imaging seems to play a complementary role to choline-based or PSMA-based PET/CT imaging in selected low- and intermediate-risk PCa patients for better characterization and eventually biopsy guidance of prostate cancer disease.