Structural Basis of Stereospecific Vanadium-Dependent Haloperoxidase Family Enzymes in Napyradiomycin Biosynthesis.

Vanadium-dependent haloperoxidases (VHPOs) from Streptomyces bacteria differ from their counterparts in fungi, macroalgae, and other bacteria by catalyzing organohalogenating reactions with strict regiochemical and stereochemical control. While this group of enzymes collectively uses hydrogen peroxide to oxidize halides for incorporation into electron-rich organic molecules, the mechanism for the controlled transfer of highly reactive chloronium ions in the biosynthesis of napyradiomycin and merochlorin antibiotics sets the Streptomyces vanadium-dependent chloroperoxidases apart. Here we report high-resolution crystal structures of two homologous VHPO family members associated with napyradiomycin biosynthesis, NapH1 and NapH3, that catalyze distinctive chemical reactions in the construction of meroterpenoid natural products. The structures, combined with site-directed mutagenesis and intact protein mass spectrometry studies, afforded a mechanistic model for the asymmetric alkene and arene chlorination reactions catalyzed by NapH1 and the isomerase activity catalyzed by NapH3. A key lysine residue in NapH1 situated between the coordinated vanadate and the putative substrate binding pocket was shown to be essential for catalysis. This observation suggested the involvement of the ε-NH2, possibly through formation of a transient chloramine, as the chlorinating species much as proposed in structurally distinct flavin-dependent halogenases. Unexpectedly, NapH3 is modified post-translationally by phosphorylation of an active site His (τ-pHis) consistent with its repurposed halogenation-independent, α-hydroxyketone isomerase activity. These structural studies deepen our understanding of the mechanistic underpinnings of VHPO enzymes and their evolution as enantioselective biocatalysts.

Observations on the pollination and breeding systems of two Corybas species (Diurideae; Orchidaceae) by fungus gnats (Mycetophilidae) in southwestern Yunnan, China.

Modes of floral presentation in some angiosperms attract flies that eat and/or oviposit on seasonal fruiting bodies of fungi. Mushroom mimesis by orchid flowers has been speculated in the geoflorous, Indo-Malaysian-Australasian, genus Corybas s.l. for decades but most studies remain fragmentary and are often inconclusive. Here we report the roles of fungus gnats as pollinators of Corybas geminigibbus and C. shanlinshiensis in southwestern Yunnan, China, combining results of field observations, lab analyses, and manipulative experiments. Hand pollination experiments suggested both species were self-compatible but incapable of mechanical self-pollination, thereby requiring pollinators for fruit production. A female of a Phthinia sp. (Mycetophilidae) carried a pollinarium of C. geminigibbus dorsally on its thorax. Two females and one male of Exechia sp. (Mycetophilidae) visiting flowers of C. shanlinshiensis carried dorsal depositions of pollinaria on their thoraces. Mycetophilid eggs were not found in the flowers of either species. The comparative fragrance analyses of these flowers and three co-fruiting mushroom species did not suggest that either orchid species was a brood-site mimic. This is the first confirmation of the dispersal of pollinaria of Corybas species by fungus gnats in subtropical-temperate Asia.

Preclinical investigations using [177Lu]Lu-Ibu-DAB-PSMA toward its clinical translation for radioligand therapy of prostate cancer.

[177Lu]Lu-Ibu-DAB-PSMA was previously characterized with moderate albumin-binding properties enabling high tumor accumulation but reasonably low retention in the blood. The aim of this study was to investigate [177Lu]Lu-Ibu-DAB-PSMA in preclinical in vivo experiments and compare its therapeutic efficacy and potential undesired side effects with those of [177Lu]Lu-PSMA-617 and the previously developed [177Lu]Lu-PSMA-ALB-56. BALB/c nude mice without tumors were investigated on Day 10 and 28 after injection of 10 MBq radioligand. It was revealed that most plasma parameters were in the same range for all groups of mice and histopathological examinations of healthy tissue did not show any alternations in treated mice as compared to untreated controls. Based on these results, a therapy study over twelve weeks was conducted with PC-3 PIP tumor-bearing mice for comparison of the radioligands's therapeutic efficacy up to an activity of 10 MBq (1 nmol) per mouse. In agreement with the increased mean absorbed tumor dose, [177Lu]Lu-Ibu-DAB-PSMA (~ 6.6 Gy/MBq) was more effective to inhibit tumor growth than [177Lu]Lu-PSMA-617 (~ 4.5 Gy/MBq) and only moderately less potent than [177Lu]Lu-PSMA-ALB-56 (~ 8.1 Gy/MBq). As a result, the survival of mice treated with 2 MBq of an albumin-binding radioligand was significantly increased (p < 0.05) compared to that of mice injected with [177Lu]Lu-PSMA-617 or untreated controls. The majority of mice treated with 5 MBq or 10 MBq [177Lu]Lu-Ibu-DAB-PSMA or [177Lu]Lu-PSMA-ALB-56 were still alive at study end. Hemograms of immunocompetent mice injected with 30 MBq [177Lu]Lu-Ibu-DAB-PSMA or 30 MBq [177Lu]Lu-PSMA-617 showed values in the same range as untreated controls. This was, however, not the case for mice treated with [177Lu]Lu-PSMA-ALB-56 which revealed a drop in lymphocytes and hemoglobin at Day 10 and Day 28 after injection. The data of this study demonstrated a significant therapeutic advantage of [177Lu]Lu-Ibu-DAB-PSMA over [177Lu]Lu-PSMA-617 and a more favorable safety profile as compared to that of [177Lu]Lu-PSMA-ALB-56. Based on these results, [177Lu]Lu-Ibu-DAB-PSMA may has the potential for a clinical translation.

Phase II trial demonstrates the efficacy and safety of individualized, dosimetry-based 177Lu-DOTATATE treatment of NET patients.

PURPOSE: Radionuclide therapy with 177Lu-DOTATATE is well established for patients with advanced somatostatin receptor-positive neuroendocrine tumors with a standard schedule of 7.4 GBq at four occasions. However, this approach does not consider individual variability affecting the tumor radiation dose or dose to organs at risk. Therefore, it is important to assess more personalized strategies. The aim of this phase II trial was to evaluate individualized 177Lu-DOTATATE for which the number of cycles varied based on renal dosimetry. METHODS: Patients were eligible if they had a progressive, somatostatin receptor-positive neuroendocrine tumor with a Ki 67 labeling index < 20%. They received cycles of 7.4 GBq of 177Lu-DOTATATE at 10 ± 2-week intervals until a predefined radiation dose to the kidneys was reached. The primary endpoint was objective tumor response (RECIST v 1.1). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity (CTCAE v. 4.0). RESULTS: Ninety-six patients who had received a median of 5 cycles (range 1-9) were evaluable for efficacy. The objective tumor response was 16% partial response, 66% stable disease, and 19% progressive disease. The median PFS and OS were 29 months and 47 months, respectively, and were significantly associated with kidney dose, performance status, and Ki 67 levels but not with tumor origin. The overall toxicity was mild, and the most common events were grade 1-2 anemia, thrombocytopenia, fatigue, nausea, and diarrhea. Grade 3-4 toxicity occurred in < 10% of patients and was mostly hematological, with no grade 3-4 renal toxicity. CONCLUSION: Individualized treatment with 177Lu-DOTATATE based on renal dosimetry is clearly feasible with low toxicity and promising efficacy, showing the potential to further improve outcome beyond the standard approach, and should be further assessed in randomized trials. TRIAL REGISTRATION: EudraCT 2011-000,240-16. NCT01456078. https://clinicaltrials.gov/ct2/show/NCT01456078.

EANM dosimetry committee recommendations for dosimetry of 177Lu-labelled somatostatin-receptor- and PSMA-targeting ligands.

The purpose of the EANM Dosimetry Committee is to provide recommendations and guidance to scientists and clinicians on patient-specific dosimetry. Radiopharmaceuticals labelled with lutetium-177 (177Lu) are increasingly used for therapeutic applications, in particular for the treatment of metastatic neuroendocrine tumours using ligands for somatostatin receptors and prostate adenocarcinoma with small-molecule PSMA-targeting ligands. This paper provides an overview of reported dosimetry data for these therapies and summarises current knowledge about radiation-induced side effects on normal tissues and dose-effect relationships for tumours. Dosimetry methods and data are summarised for kidneys, bone marrow, salivary glands, lacrimal glands, pituitary glands, tumours, and the skin in case of radiopharmaceutical extravasation. Where applicable, taking into account the present status of the field and recent evidence in the literature, guidance is provided. The purpose of these recommendations is to encourage the practice of patient-specific dosimetry in therapy with 177Lu-labelled compounds. The proposed methods should be within the scope of centres offering therapy with 177Lu-labelled ligands for somatostatin receptors or small-molecule PSMA.

Promising potential of [177Lu]Lu-DOTA-folate to enhance tumor response to immunotherapy-a preclinical study using a syngeneic breast cancer model.

PURPOSE: It was previously demonstrated that radiation effects can enhance the therapy outcome of immune checkpoint inhibitors. In this study, a syngeneic breast tumor mouse model was used to investigate the effect of [177Lu]Lu-DOTA-folate as an immune stimulus to enhance anti-CTLA-4 immunotherapy. METHODS: In vitro and in vivo studies were performed to characterize NF9006 breast tumor cells with regard to folate receptor (FR) expression and the possibility of tumor targeting using [177Lu]Lu-DOTA-folate. A preclinical therapy study was performed over 70 days with NF9006 tumor-bearing mice that received vehicle only (group A); [177Lu]Lu-DOTA-folate (5 MBq; 3.5 Gy absorbed tumor dose; group B); anti-CTLA-4 antibody (3 × 200 µg; group C), or both agents (group D). The mice were monitored regarding tumor growth over time and signs indicating adverse events of the treatment. RESULTS: [177Lu]Lu-DOTA-folate bound specifically to NF9006 tumor cells and tissue in vitro and accumulated in NF9006 tumors in vivo. The treatment with [177Lu]Lu-DOTA-folate or an anti-CTLA-4 antibody had only a minor effect on NF9006 tumor growth and did not substantially increase the median survival time of mice (23 day and 19 days, respectively) as compared with untreated controls (12 days). [177Lu]Lu-DOTA-folate sensitized, however, the tumors to anti-CTLA-4 immunotherapy, which became obvious by reduced tumor growth and, hence, a significantly improved median survival time of mice (> 70 days). No obvious signs of adverse effects were observed in treated mice as compared with untreated controls. CONCLUSION: Application of [177Lu]Lu-DOTA-folate had a positive effect on the therapy outcome of anti-CTLA-4 immunotherapy. The results of this study may open new perspectives for future clinical translation of folate radioconjugates.

Pituitary Function after High-Dose 177Lu-DOTATATE Therapy and Long-Term Follow-Up.

INTRODUCTION: The pituitary gland has a high expression of somatostatin receptors and is therefore a potential organ at risk for radiation-induced toxicity after 177Lu-DOTATATE treatment. OBJECTIVE: To study changes in pituitary function in patients with neuroendocrine tumors (NETs) treated with dosimetry-based 177Lu-DOTATATE to detect possible late toxicity. METHODS: 68 patients from a phase II clinical trial of dosimetry-based, individualized 177Lu-DOTATATE therapy were included in this analysis. Patients had received a median of 5 (range 3-9) treatment cycles of 7.4 GBq/cycle. Median follow-up was 30 months (range 11-89). The GH/IGF-1 axis, gonadotropins, and adrenal and thyroid axes were analyzed at baseline and on a yearly basis thereafter. Percent changes in hormonal levels over time were analyzed statistically using a linear mixed model and described graphically using box plots. The absorbed radiation dose to the pituitary was estimated based on post-therapeutic imaging, and the results analyzed versus percent change in IGF-1 levels over time. RESULTS: A statistically significant decrease in IGF-1 levels was found (p < 0.005), which correlated with the number of treatment cycles (p = 0.008) and the absorbed radiation dose (p = 0.03). A similar decrease, although non-significant, was seen in gonadotropins in postmenopausal women, while in men there was an increase during the first years after therapy, after which the levels returned to baseline. No change was observed in the adrenal or thyroid axes. CONCLUSIONS: No signs of severe endocrine disorders were detected, although a significant decrease in the GH/IGF-1 axis was found, where dosimetric analyses indicated radiation-induced damage to the pituitary gland as a probable cause.

Everolimus-facilitated calcineurin inhibitor reduction in Asian de novo kidney transplant recipients: 2-year results from the subgroup analysis of the TRANSFORM study.

OBJECTIVE: We analyzed the efficacy and safety of an everolimus with reduced-exposure calcineurin inhibitor (EVR+rCNI) versus mycophenolic acid with standard-exposure CNI (MPA+sCNI) regimen in Asian patients from the TRANSFORM study. METHODS: In this 24-month, open-label study, de novo kidney transplant recipients (KTxRs) were randomized (1:1) to receive EVR+rCNI or MPA+sCNI, along with induction therapy and corticosteroids. RESULTS: Of the 2037 patients randomized in the TRANSFORM study, 293 were Asian (EVR+rCNI, N = 136; MPA+sCNI, N = 157). At month 24, EVR+rCNI was noninferior to MPA+sCNI for the binary endpoint of estimated glomerular filtration rate (eGFR) < 50 ml/min/1.73 m2 or treated biopsy-proven acute rejection (27.0% vs. 29.2%, P = .011 for a noninferiority margin of 10%). Graft loss and death were reported for one patient each in both arms. Mean eGFR was higher in EVR+rCNI versus MPA+sCNI (72.2 vs. 66.3 ml/min/1.73 m2 , P = .0414) even after adjusting for donor type and donor age (64.3 vs. 59.3 ml/min/1.73 m2 , P = .0582). Overall incidence of adverse events was comparable. BK virus (4.4% vs. 12.1%) and cytomegalovirus (4.4% vs. 13.4%) infections were significantly lower in the EVR+rCNI arm. CONCLUSION: This subgroup analysis in Asian de novo KTxRs demonstrated that the EVR+rCNI versus MPA+sCNI regimen provides comparable antirejection efficacy, better renal function, and reduced viral infections (NCT01950819).

Albumin-Binding PSMA Radioligands: Impact of Minimal Structural Changes on the Tissue Distribution Profile.

The concept of using ibuprofen as an albumin-binding entity was recently demonstrated by the development of [177Lu]Lu-Ibu-PSMA-01. In the present study, we designed a novel ibuprofen-containing radioligand (Ibu-PSMA-02) with subtle structural changes regarding the linker entity in order to investigate a potential impact on the in vitro and in vivo properties. Ibu-PSMA-02 was prepared using solid-phase synthesis techniques and labeled with lutetium-177. [177Lu]Lu-Ibu-PSMA-02 was evaluated in vitro with regard to its plasma protein-binding properties, PSMA affinity and uptake into PSMA-expressing PC-3 PIP tumor cells. The tissue distribution profile of [177Lu]Lu-Ibu-PSMA-02 was assessed in tumor-bearing mice and dose estimations were performed. The in vitro characteristics of [177Lu]Lu-Ibu-PSMA-02 were similar to those previously obtained for [177Lu]Lu-Ibu-PSMA-01 with respect to plasma protein-binding, PSMA affinity and tumor cell uptake. The in vivo studies revealed, however, an unprecedentedly high uptake of [177Lu]Lu-Ibu-PSMA-02 in PC-3 PIP tumors, resulting in an increased absorbed tumor dose of 7.7 Gy/MBq as compared to 5.1 Gy/MBq calculated for [177Lu]Lu-Ibu-PSMA-01. As a consequence of the high tumor accumulation, [177Lu]Lu-Ibu-PSMA-02 showed higher tumor-to-background ratios than [177Lu]Lu-Ibu-PSMA-01. This study exemplified that smallest structural changes in the linker entity of PSMA radioligands may have a significant impact on their pharmacokinetic profiles and, thus, may be applied as a means for ligand design optimization.

Two-year outcomes in de novo renal transplant recipients receiving everolimus-facilitated calcineurin inhibitor reduction regimen from the TRANSFORM study.

TRANSFORM (TRANSplant eFficacy and safety Outcomes with an eveRolimus-based regiMen) was a 24-month, prospective, open-label trial in 2037 de novo renal transplant recipients randomized (1:1) within 24 hours of transplantation to receive everolimus (EVR) with reduced-exposure calcineurin inhibitor (EVR + rCNI) or mycophenolate with standard-exposure CNI. Consistent with previously reported 12-month findings, noninferiority of the EVR + rCNI regimen for the primary endpoint of treated biopsy-proven acute rejection (tBPAR) or estimated glomerular filtration rate (eGFR) <50 mL/min per 1.73 m2 was achieved at month 24 (47.9% vs 43.7%; difference = 4.2%; 95% confidence interval = -0.3, 8.7; P = .006). Mean eGFR was stable up to month 24 (52.6 vs 54.9 mL/min per 1.73 m2 ) in both arms. The incidence of de novo donor-specific antibodies (dnDSA) was lower in the EVR + rCNI arm (12.3% vs 17.6%) among on-treatment patients. Although discontinuation rates due to adverse events were higher with EVR + rCNI (27.2% vs 15.0%), rates of cytomegalovirus (2.8% vs 13.5%) and BK virus (5.8% vs 10.3%) infections were lower. Cytomegalovirus infection rates were significantly lower with EVR + rCNI even in the D+/R- high-risk group (P < .0001). In conclusion, the EVR + rCNI regimen offers comparable efficacy and graft function with low tBPAR and dnDSA rates and significantly lower incidence of viral infections relative to standard-of-care up to 24 months. Clinicaltrials.gov number: NCT01950819.

Terbium-161 for PSMA-targeted radionuclide therapy of prostate cancer.

PURPOSE: The prostate-specific membrane antigen (PSMA) has emerged as an interesting target for radionuclide therapy of metastasized castration-resistant prostate cancer (mCRPC). The aim of this study was to investigate 161Tb (T1/2 = 6.89 days; Eß͞av = 154 keV) in combination with PSMA-617 as a potentially more effective therapeutic alternative to 177Lu-PSMA-617, due to the abundant co-emission of conversion and Auger electrons, resulting in an improved absorbed dose profile. METHODS: 161Tb was used for the radiolabeling of PSMA-617 at high specific activities up to 100 MBq/nmol. 161Tb-PSMA-617 was tested in vitro and in tumor-bearing mice to confirm equal properties, as previously determined for 177Lu-PSMA-617. The effects of 161Tb-PSMA-617 and 177Lu-PSMA-617 on cell viability (MTT assay) and survival (clonogenic assay) were compared in vitro using PSMA-positive PC-3 PIP tumor cells. 161Tb-PSMA-617 was further investigated in therapy studies using PC-3 PIP tumor-bearing mice. RESULTS: 161Tb-PSMA-617 and 177Lu-PSMA-617 displayed equal in-vitro properties and tissue distribution profiles in tumor-bearing mice. The viability and survival of PC-3 PIP tumor cells were more reduced when exposed to 161Tb-PSMA-617 as compared to the effect obtained with the same activities of 177Lu-PSMA-617 over the whole investigated concentration range. Treatment of mice with 161Tb-PSMA-617 (5.0 MBq/mouse and 10 MBq/mouse, respectively) resulted in an activity-dependent increase of the median survival (36 vs 65 days) compared to untreated control animals (19 days). Therapy studies to compare the effects of 161Tb-PSMA-617 and 177Lu-PSMA-617 indicated the anticipated superiority of 161Tb over 177Lu. CONCLUSION: 161Tb-PSMA-617 showed superior in-vitro and in-vivo results as compared to 177Lu-PSMA-617, confirming theoretical dose calculations that indicate an additive therapeutic effect of conversion and Auger electrons in the case of 161Tb. These data warrant more preclinical research for in-depth investigations of the proposed concept, and present a basis for future clinical translation of 161Tb-PSMA-617 for the treatment of mCRPC.

The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study.

Background and Aims: Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods: The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results: Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions: Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades.

Everolimus with Reduced Calcineurin Inhibitor Exposure in Renal Transplantation.

Background Everolimus permits reduced calcineurin inhibitor (CNI) exposure, but the efficacy and safety outcomes of this treatment after kidney transplant require confirmation.Methods In a multicenter noninferiority trial, we randomized 2037 de novo kidney transplant recipients to receive, in combination with induction therapy and corticosteroids, everolimus with reduced-exposure CNI (everolimus arm) or mycophenolic acid (MPA) with standard-exposure CNI (MPA arm). The primary end point was treated biopsy-proven acute rejection or eGFR<50 ml/min per 1.73 m2 at post-transplant month 12 using a 10% noninferiority margin.Results In the intent-to-treat population (everolimus n=1022, MPA n=1015), the primary end point incidence was 48.2% (493) with everolimus and 45.1% (457) with MPA (difference 3.2%; 95% confidence interval, -1.3% to 7.6%). Similar between-treatment differences in incidence were observed in the subgroups of patients who received tacrolimus or cyclosporine. Treated biopsy-proven acute rejection, graft loss, or death at post-transplant month 12 occurred in 14.9% and 12.5% of patients treated with everolimus and MPA, respectively (difference 2.3%; 95% confidence interval, -1.7% to 6.4%). De novo donor-specific antibody incidence at 12 months and antibody-mediated rejection rate did not differ between arms. Cytomegalovirus (3.6% versus 13.3%) and BK virus infections (4.3% versus 8.0%) were less frequent in the everolimus arm than in the MPA arm. Overall, 23.0% and 11.9% of patients treated with everolimus and MPA, respectively, discontinued the study drug because of adverse events.Conclusions In kidney transplant recipients at mild-to-moderate immunologic risk, everolimus was noninferior to MPA for a binary composite end point assessing immunosuppressive efficacy and preservation of graft function.

A Major Step in Opening the Black Box of High-Molecular-Weight Dissolved Organic Nitrogen by Isotopic Labeling of Synechococcus and Multibond Two-Dimensional NMR.

Dissolved organic nitrogen (DON) comprises the largest pool of fixed N in the surface ocean, yet its composition has remained poorly constrained. Knowledge of the chemical composition of this nitrogen pool is crucial for understanding its biogeochemical function and reactivity in the environment. Previous work has suggested that high-molecular-weight (high-MW) DON exists only in two closely related forms, the secondary amides of peptides and of N-acetylated hexose sugars. Here, we demonstrate that the chemical structures of high-MW DON may be much more diverse than previously thought. We couple isotopic labeling of cyanobacterially derived dissolved organic matter with advanced two-dimensional NMR spectroscopy to open the "black box" of uncharacterized high-MW DON. Using multibond NMR correlations, we have identified novel N-methyl-containing amines and amides, primary amides, and novel N-acetylated sugars, which together account for nearly 50% of cyanobacterially derived high-MW DON. This study reveals unprecedented compositional details of the previously uncharacterized DON pool and outlines the means to further advance our understanding of this biogeochemically and globally important reservoir of organic nitrogen.

Individualised 177Lu-DOTATATE treatment of neuroendocrine tumours based on kidney dosimetry.

PURPOSE: To present data from an interim analysis of a Phase II trial designed to determine the feasibility, safety, and efficacy of individualising treatment based on renal dosimetry, by giving as many cycles as possible within a maximum renal biologically effective dose (BED). METHOD: Treatment was given with repeated cycles of 7.4 GBq 177Lu-DOTATATE at 8-12-week intervals. Detailed dosimetry was performed in all patients after each cycle using a hybrid method (SPECT + planar imaging). All patients received treatment up to a renal BED of 27 ± 2 Gy (α/ß = 2.6 Gy) (Step 1). Selected patients were offered further treatment up to a renal BED of 40 ± 2 Gy (Step 2). Renal function was followed by estimation and measurement of the glomerular filtration rate (GFR). RESULTS: Fifty-one patients were included in the present analysis. Among the patients who received treatment as planned, the median number of cycles in Step 1 was 5 (range 3-7), and for those who completed Step 2 it was 7 (range 5-8); 73% were able to receive >4 cycles. Although GFR decreased in most patients after the completion of treatment, no grade 3-4 toxicity was observed. Patients with a reduced baseline GFR seemed to have an increased risk of GFR decline. Five patients received treatment in Step 2, none of whom exhibited a significant reduction in renal function. CONCLUSIONS: Individualising PRRT using renal dosimetry seems feasible and safe and leads to an increased number of cycles in the majority of patients. The trial will continue as planned.

Preclinical Comparison of Albumin-Binding Radiofolates: Impact of Linker Entities on the in Vitro and in Vivo Properties.

Tumor targeting with folic acid radioconjugates has been proposed as a promising strategy for radionuclide therapy of folate receptor α (FR)-positive cancer. Recently, it was shown that modification of radiofolates with an albumin-binding entity increased the tumor-to-kidney ratios of accumulated radioactivity in mice. The goal of this study was to evaluate the lead compound cm10 and compare it with new albumin-binding folate conjugates. Compound cm12 was designed with a long spacer consisting of a PEG-11 entity, and compound cm13 contained a short alkane chain between the albumin-binding moiety and folic acid. All of the derivatives were labeled with 177Lu (t1/2 = 6.65 days, Eß-,average = 134 keV; Eγ = 113 keV, 208 keV), a clinically established radionuclide for therapeutic purposes. The evaluation revealed that all of the albumin-binding radiofolates exhibited increased in vitro stability compared with the reference compound (177Lu-cm14) without albumin binder. Serum protein binding, determined with an ultrafiltration assay, was high (>88%) for the derivatives with albumin-binding entities. The FR-binding affinity was in the same range (KD = 4.0-7.5 nM) for all of the radiofolates, independent of the albumin-binding entity and spacer length. FR-specific uptake was proven in vitro using FR-positive KB tumor cells. In vivo studies with KB-tumor-bearing mice were performed in order to assess the tissue distribution profile of the novel radiofolates. 177Lu-cm13 showed high tumor uptake at late time points (13.3 ± 2.94% IA/g, 48 h p.i.) and tumor-to-kidney ratios (0.59 ± 0.03, 48 h p.i.) in the same range as 177Lu-cm10 (0.55 ± 0.07, 48 h p.i.). However, the tumor-to-kidney ratio of 177Lu-cm12 (0.28 ± 0.07, 48 h p.i.) was reduced compared with 177Lu-cm10 and 177Lu-cm13. The results of this study indicate that the spacer entity between folic acid and the albumin binder is of critical importance with regard to the tissue distribution profile of the radiofolate. The PEG spacer compromised the beneficial effects of the lead compound, but the design with a short alkane spacer appeared to be promising. Future studies will focus on the design of radiofolates with lipophilic and more rigid spacer entities, which may allow a further improvement of their tissue distribution profiles.

The Degree of Surgical Frontal Volume Correction in Metopic Synostosis Determines Long-Term Outcomes.

Metopic synostosis results in a keel-shaped forehead, reduced frontal intracranial volume (ICV), and lower frontal to total volume ratio. The ratio improves with cranioplasty, but at 3 years of age, the ratio is still not normalized when compared to that in normal children. The aim of the present study was to investigate whether a low frontal to total ICV ratio at 3 years of age was due to relapse or insufficient correction.All children surgically treated for metopic synostosis in combination with a spring at Sahlgrenska University Hospital with subsequent spring extraction between 2002 and 2008 (n = 20) were included. A MATLAB program was used to measure frontal and total ICV.Preoperatively, the frontal to total ICV ratio was 9.8 ±â€Š1.3% (mean ±â€Šstandard deviation). At spring removal, 6 months after cranioplasty, the ratio had increased to 11.8 ±â€Š2.4%. At 3 years of age, the ratio was 11.6 ±â€Š1.9%. In age-matched normal children, the ratio was 14.4 ±â€Š1.9% preoperatively, 15.3 ±â€Š2.2% at time of spring extraction, and 13.4 ±â€Š1.4% at 3 years of age.Cranioplasty thus improved the frontal to total ICV ratio, but did not normalize it. The ratio did not change from 6 months after the cranioplasty to 3 years of age. These results indicate that a more pronounced frontal volume correction during cranioplasty is necessary to achieve a normalized distribution of ICV in metopic synostosis.

Temporal Deformity Objectively Measured Before and After Surgery for Metopic Synostosis: Retrusion Rather than Hollowing.

The temporal contour deformity typical of metopic synostosis is often referred to as temporal hollowing, but has not been quantitatively defined. This deformity is present before surgery and remains to a varying extent at long-term follow-up. The present study aimed to objectively evaluate the degree of this contour deformity in metopic synostosis before and after surgical correction.All children surgically treated for metopic synostosis at Sahlgrenska University Hospital between 2002 and 2014 (n = 120) with appropriate computed tomography scans (n = 160) performed preoperatively and/or at follow-up at 3 years of age were included. Depending on age, 1 of 2 surgical techniques was used. Children presenting before the age of 6 months were treated with frontal remodeling in combination with a spring (S group), whereas children older than 6 months were treated with a bone transplant (BT group). The bony temporal deformity was measured with a semiautomatic MATLAB program and patients were compared to sex- and age-matched controls.The deformity was significantly reduced in both groups (P < 0.001). In the S group, it was reduced from a mean ±â€Šstandard deviation of 3.6 ±â€Š1.9% to 1.0 ±â€Š1.2% and in the BT group, it was reduced from 3.3% ±â€Š1.4% to 1.1% ±â€Š0.8%.The contour deformity in metopic synostosis is present both before and after surgery and should therefore be termed temporal retrusion (TR). This assessment method enables objective comparison of TR before and after surgical correction and is a potential tool to evaluate TR in metopic synostosis.