Lutetium-Induced Ultrafine PtRu Nanoclusters with a High Electrochemical Surface Area for Direct Methanol Fuel Cells at Alleviated Temperatures

PtRu alloys have been recognized as the state-of-the-art catalysts for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). However, their applications in DMFCs are still less efficient in terms of both catalytic activity and durability. Rare earth (RE) metals have been recognized as attractive elements to tune the catalytic activity, while it is still a world-class challenge to synthesize well-dispersed Pt-RE alloys. Herein, we developed a novel hydrogen-assisted magnesiothermic reduction strategy to prepare a highly dispersed carbon-supported lutetium-doped PtRu catalyst with ultrafine nanoclusters and atomically dispersed Ru sites. The PtRuLu catalyst shows an outstanding high electrochemical surface area (ECSA) of 239.0 m2 gPt-1 and delivers an optimized MOR mass activity and specific activity of 632.5 mA mgPt-1 and 26 A cmPt-2 at 0.4 V vs saturated calomel electrode (SCE), which are 3.6 and 3.5 times of commercial PtRu-JM and an order higher than PtLu, respectively. These novel catalysts have been demonstrated in a high-temperature direct methanol fuel cell running in a temperature range of 180-240 °C, achieving a maximum power density of 314.3 mW cm-2. The AC-STEM imaging, in situ ATR-IR spectroscopy, and DFT calculations disclose that the high performance is resulted from the highly dispersed PtRuLu nanoclusters and the synergistic effect of the atomically dispersed Ru sites with PtRuLu nanoclusters, which significantly reduces the CO* intermediates coverage due to the promoted water activation to form the OH* to facilitate the CO* removal.

Clinical Management of Advanced Prostate Cancer: Where Does Radiopharmaceutical Therapy Fit in the Treatment Algorithm?

Most men with newly appreciated metastatic prostate cancer are optimally treated with a backbone consisting of androgen receptor-directed therapy with or without taxane chemotherapy. Despite improvements in disease outcomes, prostate cancer remains an extremely heterogeneous disease with variable mechanisms of therapeutic resistance. As a result, it remains a leading cause of cancer-related death in men. Radiopharmaceutical therapy has emerged as an alternative, non-androgen receptor-directed treatment modality for metastatic castration-resistant prostate cancer that impacts patient survival and represents a potentially more personalized approach. In this review, we aim to outline the current treatment landscape for metastatic prostate cancer with a focus on radiopharmaceutical therapy, specifically 177Lu-PSMA-617. In addition, we illustrate various clinical challenges with 177Lu-PSMA-617 treatment to date and explore investigative efforts to leverage radiopharmaceutical therapies as part of combination regimens or earlier in the treatment algorithm to further improve patient outcomes. Finally, we introduce ongoing studies of alternative radiopharmaceutical therapies in metastatic prostate cancer that may be incorporated into the treatment algorithm pending further study.

Crystal structure of tetra-phenyl phosphate tetra-kis-[dimethyl (2,2,2-tri-chloro-acet-yl)phos-pho-ramidato]lutetium(III), PPh4[LuL4]

A lutetium(III) complex based on the anion of the ligand dimethyl (2,2,2-tri-chloro-acet-yl)phospho-ramidate (HL) and tetra-phenylphosphonium, of composition PPh4[LuL 4] (L = CAPh = carbacyl-amido-phosphate), or (C24H20)[Lu(C4H6Cl3NO4P)4], has been synthesized and structurally characterized. The X-ray diffraction study of the compound revealed that the lutetium ion is surrounded by four bis-chelating CAPh ligands, forming the complex anion [LuL 4]- with a coordination number of 8[O] for LuIII, while PPh4 + serves as a counter-ion. The coordination geometry around the Lu3+ ion was determined to be a nearly perfect triangular dodeca-hedron. The complex crystallizes in the monoclinic crystal system, space group P21/c, with four mol-ecules in the unit cell. Weak hydrogen bonds O⋯HC(Ph), Cl⋯HC(Ph) and N⋯HC(Ph) are formed between the cations and anions. For a comparative study, HL-based structures were retrieved from the Cambridge Structural Database (CSD) and their geometries and conformations are discussed. A Hirshfeld surface analysis was also performed.

Care Pathway at a Cancer Center for the Administration of Radiometabolic Therapy with 177Lu-PSMA in Patients with Metastatic Castration-resistant Prostate Cancer

Objectives

To present a clinical care model for the administration of 177Lu-labeled prostate-specific membrane antigen (PSMA) in radiometabolic therapy for metastatic castration-resistant prostate cancer (mCRPC) at the National Cancer Institute (NCI) of Bogotá, Colombia.

Methods

A care model was designed for patients with mCRPC based on the VISION study, a prospective, phase III, multicenter, open-label, randomized study in patients with positive 68Ga-PSMA positron emission tomography/computed tomography who had progressed to taxane and androgen therapy, to receive 177Lu-PSMA-617 combined with the best standard of care vs. the best standard of care alone. The care pathway provided to patients was developed by the Nuclear Medicine Group of the NCI and is the result of adjustments and improvements in the care process and the updating of the literature.

Results

A systematic and efficient care model was formalized and implemented for the administration of 177Lu-PSMA therapy in patients with mCRPC who had previously been treated with at least one androgen receptor pathway inhibitor and one or two taxane regimens, with evidence of disease progression.

Conclusion

An optimized process of care based on the determinants of clinical outcomes was developed for patients who received this type of radiometabolic therapy.

Microcrystalline Luminescent (Eu1-xLnx)2bdc3·nH2O (Ln = La, Gd, Lu) Antenna MOFs: Effect of Dopant Content on Structure, Particle Morphology, and Luminescent Properties

In this work, three series of micro-sized heterometallic europium-containing terephthalate MOFs, (Eu1-xLnx)2bdc3·nH2O (Ln = La, Gd, Lu), are synthesized via an ultrasound-assisted method in an aqueous medium. La3+ and Gd3+-doped terephthalates are isostructural to Eu2bdc3·4H2O. Lu3+-doped compounds are isostructural to Eu2bdc3·4H2O with Lu contents lower than 95 at.%. The compounds that are isostructural to Lu2bdc3·2.5H2O are formed at higher Lu3+ concentrations for the (Eu1-xLux)2bdc3·nH2O series. All materials consist of micrometer-sized particles. The particle shape is determined by the crystalline phase. All the synthesized samples demonstrate an "antenna" effect: a bright-red emission corresponding to the 5D0-7FJ transitions of Eu3+ ions is observed upon 310 nm excitation into the singlet electronic excited state of terephthalate ions. The fine structure of the emission spectra is determined by the crystalline phase due to the different local symmetries of the Eu3+ ions in the different kinds of crystalline structures. The photoluminescence quantum yield and 5D0 excited state lifetime of Eu3+ are equal to 11 ± 2% and 0.44 ± 0.01 ms, respectively, for the Ln2bdc3·4H2O structures. For the (Eu1-xLux)2bdc3·2.5H2O compounds, significant increases in the photoluminescence quantum yield and 5D0 excited state lifetime of Eu3+ are observed, reaching 23% and 1.62 ms, respectively.

Long-Term Nephrotoxicity of 177Lu-PSMA Radioligand Therapy

β-emitting 177Lu targeting prostate-specific membrane antigen (PSMA) is an approved treatment option for metastatic castration-resistant prostate cancer. Data on its long-term nephrotoxicity are sparse. This study aimed to retrospectively evaluate post-177Lu-PSMA estimated glomerular filtration rate (eGFR) dynamics for at least 12 mo in a cohort of metastatic castration-resistant prostate cancer patients. Methods: The institutional databases of 3 German tertiary referral centers identified 106 patients who underwent at least 4 cycles of 177Lu-PSMA and had at least 12 mo of eGFR follow-up data. eGFR (by the Chronic Kidney Disease Epidemiology Collaboration formula) at 3, 6, and 12 mo after 177Lu-PSMA radioligand therapy was estimated using monoexponentially fitted curves through available eGFR data. eGFR changes were grouped (≥15%-<30%, moderate; ≥30%-<40%, severe; and ≥40%, very severe). Associations between eGFR changes (%) and nephrotoxic risk factors, prior treatment lines, and number of 177Lu-PSMA cycles were analyzed using multivariable linear regression. Results: At least moderate eGFR decreases were present in 45% (48/106) of patients; of those, nearly half (23/48) had a severe or very severe eGFR decrease. A higher number of risk factors at baseline (-4.51, P = 0.03) was associated with a greater eGFR decrease. Limitations of the study were the retrospective design, lack of a control group, and limited number of patients with a follow-up longer than 1 y. Conclusion: A considerable proportion of patients may experience moderate or severe decreases in eGFR 1 y from initiation of 177Lu-PSMA. A higher number of risk factors at baseline seems to aggravate loss of renal function. Further prospective trials are warranted to estimate the nephrotoxic potential of 177Lu-PSMA.

Prognostic Value of the De Ritis Ratio for Overall Survival in Patients with Metastatic Castration-Resistant Prostate Cancer Undergoing [177Lu]Lu-PSMA-617 Radioligand Therapy

The De Ritis ratio (=aspartate transaminase/alanine transaminase) has shown prognostic value in different cancer types. This is the first such analysis in prostate cancer patients undergoing radioligand therapy (RLT) with [177Lu]Lu-PSMA-617. This retrospective monocentric analysis included 91 patients with a median of 3 RLT cycles (range 1-6) and median cumulative activity of 17.3 GBq. Univariable Cox regression regarding overall survival (OS) included age, different types of previous treatment, metastatic patterns and different laboratory parameters before RLT. Based on multivariable Cox regression, a prognostic score was derived. Seventy-two patients (79%) died (median follow-up in survivors: 19.8 months). A higher number of previous chemotherapy lines, the presence of liver metastases, brain metastases, a higher tumor load on PSMA-PET, a higher prostate-specific antigen (PSA) level, lower red blood cell count, lower hemoglobin, higher neutrophil-lymphocyte ratio and higher De Ritis ratio were associated with shorter OS (each p < 0.05). In multivariable Cox, a higher number of chemotherapy lines (range, 0-2; p = 0.036), brain metastases (p < 0.001), higher PSA (p = 0.004) and higher De Ritis ratio before RLT (hazard ratio, 1.27 per unit increase; p = 0.023) remained significant. This prognostic score separated five groups with a significantly different median OS ranging from 4.9 to 28.1 months (log-rank test, p < 0.001). If validated independently, the De Ritis ratio could enhance multifactorial models for OS after RLT.

Optimization of Deuteron Irradiation of 176Yb for Producing 177Lu of High Specific Activity Exceeding 3000 GBq/mg

The irradiation of 176Yb with deuterons offers a promising pathway for the production of the theranostic radionuclide 177Lu. To optimize this process, calculations integrating deuteron transport, isotope production, and decay have been performed. In pure 176Yb, the undesired production of 174g+mLu occurs at higher deuteron energies, corresponding to a distribution slightly shallower than that of 177Lu. Hence, 174g+mLu can be effectively filtered out by employing either a low-energy deuteron beam or stacked foils. The utilization of stacked foils enables the production of 177Lu using a high-energy linear accelerator. Another unwanted isotope, 176mLu, is produced roughly at the same depth as 177Lu, but its concentration can be significantly reduced by selecting an appropriate post-irradiation processing time, owing to its relatively short half-life. The modeling approach extended to the mapping of yields as a function of irradiation time and post-irradiation processing time. An optimized processing time window was identified. The study demonstrates that a high-energy deuteron beam can be employed to produce 177Lu with high specific activity exceeding 3000 GBq/mg. The effect of different purity levels (ranging from 98% to 100%) was also discussed. The impurity levels have a slight impact. The modeling demonstrates the feasibility of obtaining 177Lu with a specific activity > 3000 GBq/mg and radionuclidic purity > 99.5% when using a commercially available 176Yb target of 99.6% purity.

Brightly Luminescent (TbxLu1-x)2bdc3·nH2O MOFs: Effect of Synthesis Conditions on Structure and Luminescent Properties

Luminescent, heterometallic terbium(III)-lutetium(III) terephthalate metal-organic frameworks (MOFs) were synthesized via direct reaction between aqueous solutions of disodium terephthalate and nitrates of corresponding lanthanides by using two methods: synthesis from diluted and concentrated solutions. For (Tb_xLu_1-x)₂bdc₃·nH₂O MOFs (bdc = 1,4-benzenedicarboxylate) containing more than 30 at. % of Tb³⁺, only one crystalline phase was formed: Ln₂bdc₃·4H₂O. At lower Tb³⁺ concentrations, MOFs crystallized as the mixture of Ln₂bdc₃·4H₂O and Ln₂bdc₃·10H₂O (diluted solutions) or Ln₂bdc₃ (concentrated solutions). All synthesized samples that contained Tb³⁺ ions demonstrated bright green luminescence upon excitation into the ¹ππ* excited state of terephthalate ions. The photoluminescence quantum yields (PLQY) of the compounds corresponding to the Ln₂bdc₃ crystalline phase were significantly larger than for Ln₂bdc₃·4H₂O and Ln₂bdc₃·10H₂O phases due to absence of quenching from water molecules possessing high-energy O-H vibrational modes. One of the synthesized materials, namely, (Tb_0.1Lu_0.9)₂bdc₃·1.4H₂O, had one of the highest PLQY among Tb-based MOFs, 95%.

Lutetium-177-PSMA-617: A Vision of the Future

In the last decade, many life-prolonging therapeutic options have emerged for metastatic castration-resistant prostate cancer (mCRPC). The recent VISION trial is the first to demonstrate a survival benefit of Lutetium-177[¹⁷⁷Lu]Lu-PSMA-617 in post-chemotherapy mCRPC. This journal club reviews the VISION trial in the context of the earlier TheraP trial of [¹⁷⁷Lu]Lu-PSMA-617 in mCRPC post docetaxel and androgen pathway inhibition, to provide direction for the real-world application of [¹⁷⁷Lu]Lu-PSMA-617. Treatment in the control groups differed significantly between both trials and may have influenced outcomes: TheraP mandated cabazitaxel whereas VISION’s design could not allow it. In both trials, [¹⁷⁷Lu]Lu-PSMA-617 had a good safety profile, with common adverse events being fatigue, nausea, dry mouth, marrow suppression and diarrhea. Given its efficacy and favorable safety even in heavily pre-treated patients, [¹⁷⁷Lu]Lu-PSMA-617 provides hope to mCRPC patients and may be applied to earlier disease stages in future investigations.

Single Center Experience with a 4-Week 177Lu-PSMA-617 Treatment Interval in Patients with Metastatic Castration-Resistant Prostate Cancer

Background: 177Lu-PSMA-617 is a promising theragnostic treatment for metastatic castration-resistant prostate cancer (mCRPC). However, both the optimal treatment dose and interval in mCRPC and the rate of identification of responders from non-responders among possible treatment candidates are unknown. Methods: 62 men with mCRPC who were treated with 177Lu-PSMA-617 during 1/2017−2/2019 were included in the study. Treatment responses, overall survival (OS) and progression free survival (PFS) were determined. The median follow-up time was 1.4 years (IQR 0.5−2.2). Tumor volume of metastases (MTV), SUVmax and tumor lesion activity (TLA) were quantitated from pre-treatment PSMA PET/CT images together with pre-treatment PSA. Results: An average of three treatment cycles (2−5) were given within a four-week interval. PFS was 4.9 months (2.4−9.6) and OS was 17.2 months (6−26.4). There were no major adverse events reported. A significant PSA response of >50% was found in 58.7% of patients, which was significantly associated with longer OS, p < 0.004. PSA response was not associated with staging PSMA-derived parameters. Conclusions: 177Lu-PSMA-617 treatment in four-week intervals was safe and effective. Almost 60% of patients had a significant PSA response, which was associated with better OS. Pre-treatment PSA kinetics or staging PSMA PET/CT-derived parameters were not helpful in identifying treatment responders from non-responders; better biomarkers are needed to aid in patient selection.

[Clinical Practice of 177Lu-DOTATATE in the Treatment of Neuroendocrine Tumors]

Most of the neuroendocrine tumors(NETs) overexpress the somatostatin receptor(SSTR),which provides a reliable target for SSTR-targeted peptide receptor radionuclide therapy(PRRT).Compared with drug therapy,PRRT has high objective response rate and significantly prolongs patients' survival.Moreover,the patients have good tolerance to this therapy.Considering that PRRT is in clinical trial phase in China,this article elaborates on the selection and preparation of patients,pre-treatment medications,administration methods,treatment cycles,side effects,follow-up plan,and the combination of PRRT with other drugs based on the published international guidelines in this field and our experience from clinical practice.Hoping that relevant professionals can well understand the principle of PRRT and apply it in clinical practice,we write this article to provide a basis for serving real-world patients and carrying out clinical trials.

From Concept to Regulatory Drug Approval: Lessons for Theranostics

Radiopharmaceutical therapy is an emerging treatment modality that has demonstrated increasing importance as a significant component in the treatment of cancer. Prostate cancer (PCa) remains one of the commonest solid-organ tumors and is associated with significant societal burdens. Despite significant disease heterogeneity, PCa remains an ideal candidate for radiopharmaceutical therapy because of the prolonged disease course, metastatic disease tropism, and sensitivity to radiation therapy. To date, advanced PCa remains one of the most successful arenas for the development and approval of radiopharmaceutical agents. In this review, we aim to summarize the complex processes required to obtain regulatory approval for a novel agent and highlight the limitations and hurdles specific to the approval of radiopharmaceutical agents. In advanced PCa, we outline the importance of a framework for trial design with respect to defining disease state and acceptable outcome measures-as recommended by the Prostate Cancer Clinical Trials Working Group (PCWG). Finally, using the principles mandated by the Food and Drug Administration approval process and the framework provided by the PCWG, we outline experience with the successful approval of the radiopharmaceutical agents ²²³Ra and ¹⁷⁷Lu-PSMA-617.

Pharmacological Optimization of PSMA-Based Radioligand Therapy

Prostate cancer (PCa) is the most common malignancy in men of middle and older age. The standard treatment strategy for PCa ranges from active surveillance in low-grade, localized PCa to radical prostatectomy, external beam radiation therapy, hormonal treatment and chemotherapy. Recently, the use of prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) for metastatic castration-resistant PCa has been approved. PSMA is predominantly, but not exclusively, expressed on PCa cells. Because of its high expression in PCa, PSMA is a promising target for diagnostics and therapy. To understand the currently used RLT, knowledge about pharmacokinetics (PK) and pharmacodynamics (PD) of the PSMA ligand and the PSMA protein itself is crucial. PK and PD properties of the ligand and its target determine the duration and extent of the effect. Knowledge on the concentration-time profile, the target affinity and target abundance may help to predict the effect of RLT. Increased specific binding of radioligands to PSMA on PCa cells may be associated with better treatment response, where nonspecific binding may increase the risk of toxicity in healthy organs. Optimization of the radioligand, as well as synergistic effects of concomitant agents and an improved dosing strategy, may lead to more individualized treatment and better overall survival.

[(CH3 )Al(CH2 )]12 : Methylaluminomethylene (MAM-12)

The molecular structure of enigmatic “poly(aluminium‐methyl‐methylene)” (first reported in 1968) has been unraveled in a transmetalation reaction with gallium methylene [Ga₈(CH₂)₁₂] and AlMe₃. The existence of cage‐like methylaluminomethylene moieties was initially suggested by the reaction of rare‐earth‐metallocene complex [Cp*₂Lu{(μ‐Me)₂AlMe₂}] with excess AlMe₃ affording the deca‐aluminium cluster [Cp*₄Lu₂(μ₃‐CH₂)₁₂Al₁₀(CH₃)₈] in low yield (Cp*=C₅Me₅). Treatment of [Ga₈(CH₂)₁₂] with excess AlMe₃ reproducibly gave the crystalline dodeca‐aluminium complex [(CH₃)₁₂Al₁₂(μ₃‐CH₂)₁₂] (MAM‐12). Revisiting a previous approach to “poly(aluminium‐methyl‐methylene” by using a (C₅H₅)₂TiCl₂/AlMe₃ (1 : 100) mixture led to amorphous solids displaying solubility behavior and spectroscopic features similar to those of crystalline MAM‐12. The gallium methylene‐derived MAM‐12 was used as an efficient methylene transfer reagent for ketones.

Factors influencing survival in metastatic castration resistant prostate cancer therapy

INTRODUCTION

The number of patients with metastatic castration resistant prostate cancer (mCRPC) is expecting to increase due to the long-life expectancy of those with advanced disease who are also more commonly diagnosed today because of stage migration. Several compounds are available for treating these patients.

AREAS COVERED

We reviewed currently available treatments for mCRPC, their mechanism of action and resistance and we explored possible predictors of treatment success useful to predict survival in mCRPC patients.

EXPERT OPINION

A combination of molecular, clinical, pathological, and imaging features is necessary to correctly estimate patients' risk of death. The combination of these biomarkers may allow clinicians to tailor treatments based on cancer history and patients' features. The search of predictive biomarkers remains an unmet medical need for most patients with mCRPC.

Baseline Imaging Derived Predictive Factors of Response Following [177Lu]Lu-PSMA-617 Therapy in Salvage Metastatic Castration-Resistant Prostate Cancer: A Lesion- and Patient-Based Analysis

Earlier studies have mostly identified pre-therapeutic clinical and laboratory parameters for the prediction of treatment response to [177Lu]Lu-PSMA-617 in metastatic castration resistant prostate cancer patients (mCRPC). The current study investigated whether imaging-derived factors on baseline [68Ga]Ga-PSMA-11 PET/CT can potentially predict the response after two cycles of [177Lu]Lu-PSMA-617 treatment, in a lesion- and patient-based analysis in men with mCRPC. Included patients had histologically proven mCRPC and a [68Ga]Ga-PSMA-11 PET/CT before and after two cycles of [177Lu]Lu-PSMA-617 treatment. The imaging-based response was evaluated on lesion-level (standardized uptake value (SUV) reduction) and patient-level (total lesion PSMA (TL-PSMA) reduction). In the lesion-level analysis, a clear relationship was found between SUVpeak/max and the imaging-based response to [68Ga]Ga-PSMA-11 PET/CT (most avid lesion SUVpeak/max ≥ 30% reduction) (p < 0.001), with no significant difference in cut-off values between different sites of metastases (i.e., lymph node, bone or visceral metastasis). In patient-level analysis, baseline PSA and SUVpeak values of most avid metastasis were significantly associated with imaging-based response (TL-PSMA ≥ 30% reduction) (p = 0.019 and p = 0.015). In pre-treatment with [68Ga]Ga-PSMA-11 PET/CT, a clear accumulation-response relationship in lesion-level was found for SUVpeak/max in men with mCRPC receiving two cycles of [177Lu]Lu-PSMA-617 treatment. The SUVpeak of the most avid lesion was the only image-derived factor predictive of the imaging-based response at the patient-level.

Treatment of Neuroendocrine Neoplasms with Radiolabeled Peptides-Where Are We Now

Peptide receptor radionuclide therapy (PRRT) has been one of the most successful and exciting examples of theranostics in nuclear medicine in recent decades and is now firmly embedded in many treatment algorithms for unresectable or metastatic neuroendocrine neoplasms (NENs) worldwide. It is widely considered to be an effective treatment for well- or moderately differentiated neoplasms, which express high levels of somatostatin receptors that can be selectively targeted. This review article outlines the scientific basis of PRRT in treatment of NENs and describes its discovery dating back to the early 1990s. Early treatments utilizing Indium-111, a γ-emitter, showed promise in reduction in tumor size and improvement in biochemistry, but were also met with high radiation doses and myelotoxic and nephrotoxic effects. Subsequently, stable conjugation of DOTA-peptides with β-emitting radionuclides, such as Yttrium-90 and Lutetium-177, served as a breakthrough for PRRT and studies highlighted their potential in eliciting progression-free survival and quality of life benefits. This article will also elaborate on the key trials which paved the way for its approval and will discuss therapeutic considerations, such as patient selection and administration technique, to optimize its use.

Case Report: Hypoglycemia Due to Metastatic Insulinoma in Insulin-Dependent Type 2 Diabetes Successfully Treated With 177 Lu-DOTATATE

We describe a 96-year-old man with insulin-dependent type 2 diabetes mellitus who, despite insulin cessation, presented with recurrent hypoglycemia associated with confirmed inappropriate endogenous hyperinsulinemia. ⁶⁸Ga-DOTATATE-PET/CT scans demonstrated increased uptake in the pancreatic tail with multiple large intensely active liver metastases. Liver biopsy confirmed the diagnosis of well-differentiated metastatic neuroendocrine tumor. He was unsuitable for surgical resection and long-acting somatostatin analog therapy was ineffective. Subsequent management with four cycles of Lutate [177-Lutetium-DOTA⁰-Tyr³-octreotate (¹⁷⁷Lu-DOTATATE)] resulted in resolution of hypoglycemia and ongoing clinical, biochemical, and radiological response 6 years after. This case is unique due to not only the paradoxical entity of insulinoma in insulin-dependent diabetes but also the positive sustained outcome after ¹⁷⁷Lu-DOTATATE, given that unresectable metastatic insulinoma carries a poor prognosis. We review published cases of metastatic insulinoma in patients with diabetes mellitus as well as the literature to-date investigating efficacy and safety of Lutate therapy in metastatic insulinoma.

Targeted Theranostic 111In/Lu-Nanotexaphyrin for SPECT Imaging and Photodynamic Therapy

Theranostic nanoparticles aim to integrate diagnostic imaging and therapy to facilitate image-guided treatment protocols. Herein, we present a theranostic nanotexaphyrin for prostate-specific membrane antigen (PSMA)-targeted radionuclide imaging and focal photodynamic therapy (PDT) accomplished through the chelation of metal isotopes (In, Lu). To realize nanotexaphyrin's theranostic properties, we developed a rapid and robust 111In/Lu-nanotexaphyrin radiolabeling method using a microfluidic system that achieved a high radiochemical yield (>90%). The optimized metalated nanotexaphyrin displayed excellent chemical, photo, and colloidal stabilities, potent singlet oxygen generation, and favorable plasma circulation half-life in vivo (t1/2 = 6.6 h). Biodistribution, including tumor accumulation, was characterized by NIR fluorescence, SPECT/CT imaging, and γ counting. Inclusion of the PSMA-targeting ligand enabled the preferential accumulation of 111In/Lu-nanotexaphyrin in PSMA-positive (PSMA+) prostate tumors (3.0 ± 0.3%ID/g) at 48 h with tumor vs prostate in a 2.7:1 ratio. In combination with light irradiation, the PSMA-targeting nanotexaphyrin showed a potent PDT effect and successfully inhibited PSMA+ tumor growth in a subcutaneous xenograft model. To the best of our knowledge, this study is the first demonstration of the inherent metal chelation-driven theranostic capabilities of texaphyrin nanoparticles, which, in combination with PSMA targeting, enabled prostate cancer imaging and therapy.

Narrative review: prostate-specific membrane antigen-radioligand therapy in metastatic castration-resistant prostate cancer

Radioactive-labelled ligands targeting the prostate-specific membrane antigen (PSMA), a transmembrane protein overexpressed in prostate cancer (PC), have shown promising activity in treatment of metastatic castration-resistant prostate cancer (mCRPC). PSMA-617 and PSMA-I&T (imaging and therapy), both labeled to the beta-emitter lutetium-177 (Lu177), are most frequently used in clinical routine and have shown a favorable side-effect profile. Common side effects are transient xerostomia. Severe side effects, e.g., treatment-associated myelosuppression, are rare. Currently treatment with Lu177-PSMA outside clinical trials is available for compassionate use for patients who exhausted conventional therapies. Previous retro- and prospective studies reported promising results with ≥50% PSA declines observed in at least one third of patients. Retrospective data suggests worse biochemical response in patients with visceral metastases. Preliminary data from the randomized phase II (TheraP) trial showed an improved biochemical response rate of Lu177-PSMA as compared to cabazitaxel in patients progressing after docetaxel. Following these promising data, the results of the randomized, prospective phase III VISION study are eagerly anticipated. A major challenge remains resistance to radioligand therapy with Lu177-PSMA. As an alternative, a PSMA-ligand labeled to the alpha-emitter Actinium-225 (Ac-225) may be offered to patients, which shows promising activity in patients developing progression under Lu177-PSMA at the cost of higher toxicity. Mostly permanent xerostomia is a relevant side effect resulting in treatment discontinuation in up to a quarter of patients. This review summarizes the literature on activity and toxicity of PSMA-targeted radioligand therapy in mCRPC.

Lutetium-177 Labelled PSMA Targeted Therapy in Advanced Prostate Cancer: Current Status and Future Perspectives

Patients suffering from metastatic castration-resistant prostate cancer (mCRPC) have a poor prognosis. As a further treatment option ¹⁷⁷Lutetium (Lu) prostate-specific membrane antigen (PSMA) radioligand therapy gained a significant interest of many investigators. Several publications showed great response and prolonged survival with limited adverse events. However, to this point, it still remains unclear which patients benefit the most from ¹⁷⁷Lu-PSMA therapy, and how to improve the treatment regimen to achieve best outcome while minimizing potential adverse events. The efficacy for mCRPC patients is a given fact, and with the newly published results of the VISION trial its approval is only a matter of time. Recently, investigators started to focus on treating prostate cancer patients in earlier disease stages and in combination with other compounds. This review gives a brief overview of the current state and the future perspectives of ¹⁷⁷Lu labelled PSMA radioligand therapy.

"Excess" electrons in LuGe

The monogermanide LuGe is obtained via high‐pressure high‐temperature synthesis (5–15 GPa, 1023–1423 K). The crystal structure is solved from single‐crystal X‐ray diffraction data (structure type FeB, space group Pnma, a=7.660(2) Å, b=3.875(1) Å, and c=5.715(2) Å, R_F=0.036 for 206 symmetry independent reflections). The analysis of chemical bonding applying quantum‐chemical techniques in position space was performed. It revealed—beside the expected 2c‐Ge‐Ge bonds in the germanium polyanion—rather unexpected four‐atomic bonds between lutetium atoms indicating the formation of a polycation by the excess electrons in the system Lu³⁺(2b)Ge²⁻×1 e⁻. Despite the reduced VEC of 3.5, lutetium monogermanide is following the extended 8‐N rule with the trend to form lutetium‐lutetium bonds utilizing the electrons left after satisfying the bonding needs in the anionic Ge‐Ge zigzag chain.

Synthesis and Evaluation of 68Ga- and 177Lu-Labeled (R)- vs (S)-DOTAGA Prostate-Specific Membrane Antigen-Targeting Derivatives

Prostate-specific membrane antigen (PSMA) is overexpressed in prostate cancer cells and therefore is an attractive target for prostate cancer diagnosis and radionuclide therapy. Recently, published results from clinical studies using a new PSMA-targeting PET imaging agent, [⁶⁸Ga]Ga-PSMA-093 ([⁶⁸Ga]Ga-HBED-CC-O-carboxymethyl-Tyr-CO-NH-Glu), support the development of this agent for the diagnosis of prostate cancer. In this study, the HBED-CC chelating group in PSMA-093 was replaced by stereoselective (R)- or (S)-DOTAGA. This chelating group serves not only for chelating ⁶⁸Ga but is also amendable for complexing other radioactive metals for radionuclide therapy. The corresponding optically pure (R)- and (S)-[⁶⁸Ga/¹⁷⁷Lu]-DOTAGA derivatives, (R)-[⁶⁸Ga/¹⁷⁷Lu]-13 and (S)-[⁶⁸Ga/¹⁷⁷Lu]-13, were successfully prepared. Comparison of radiolabeling, binding affinity, cell uptake, and biodistribution between the two isomers was performed. Radiolabeling of (R)-[¹⁷⁷Lu]Lu-13 and (S)-[¹⁷⁷Lu]Lu-13 at 50 °C suggested that rates of complex formation were time-dependent and the formation of (S)-[¹⁷⁷Lu]Lu-13 was distinctly faster. The rates of complex formation for the corresponding ⁶⁸Ga agents were comparable between structural isomers. The ^natGa and ^natLu equivalents showed high binding PSMA affinity (IC₅₀ = 24-111 nM), comparable to that of the parent agent, [^natGa]Ga-PSMA-093 (IC₅₀ = 34.0 nM). Results of cell uptake and biodistribution studies in PSMA-expressing PC3-PIP tumor-bearing mice appeared to show no difference between the labeled (R)- and (S)-isomers. This is the first time that a pair of [⁶⁸Ga/¹⁷⁷Lu]-(R)- and (S)-DOTAGA isomers of PSMA agents were evaluated. Results of biological studies between the isomers showed no noticeable difference; however, the distinctions on the rate of Lu complex formation should be considered in the development of new ¹⁷⁷Lu-DOTAGA-based radionuclide therapy agents in the future.

Prostate-specific membrane antigen theranostics in advanced prostate cancer: an evolving option

OBJECTIVES

To review current data for the role of prostate specific membrane antigen (PSMA) radioligand therapy (RLT) for patients with advanced prostate cancer. This review provides an update for multidisciplinary teams on the current and potential future applications of theranostics in prostate cancer.

METHODS

Narrative review focussing on PSMA as a target for RLT, and data using RESULTS: RLT with PSMA is an exciting therapeutic alternative to the existing management options already in use for patients with metastatic castrate-resistant prostate cancer (mCRPC). To date, most evidence exists regarding small-molecule PSMA inhibitors bound to beta-emitting radioisotopes such as 177Lu (Lu-PSMA). Prospective phase II data supports the safety and efficacy of Lu-PSMA in men with heavily pre-treated progressive mCRPC, and several late-phase randomised trials of Lu-PSMA are underway, with many more in the pipeline. Early results are encouraging, indicating that the theranostic approach may play a vital role in management of advanced prostate cancer and perhaps even in much earlier disease states.

CONCLUSIONS

PSMA RLT is a promising new treatment option for men with mCPRC, and may also have utility in less advanced prostate cancer.

Single-Molecule Magnets DyM2 N@C80 and Dy2 MN@C80 (M=Sc, Lu): The Impact of Diamagnetic Metals on Dy3+ Magnetic Anisotropy, Dy⋅⋅⋅Dy Coupling, and Mixing of Molecular and Lattice Vibrations

The substitution of scandium in fullerene single-molecule magnets (SMMs) DySc2 N@C80 and Dy2 ScN@C80 by lutetium has been studied to explore the influence of the diamagnetic metal on the SMM performance of dysprosium nitride clusterfullerenes. The use of lutetium led to an improved SMM performance of DyLu2 N@C80 , which shows a higher blocking temperature of magnetization (TB =9.5 K), longer relaxation times, and broader hysteresis than DySc2 N@C80 (TB =6.9 K). At the same time, Dy2 LuN@C80 was found to have a similar blocking temperature of magnetization to Dy2 ScN@C80 (TB =8 K), but substantially different interactions between the magnetic moments of the dysprosium ions in the Dy2 MN clusters. Surprisingly, although the intramolecular dipolar interactions in Dy2 LuN@C80 and Dy2 ScN@C80 are of similar strength, the exchange interactions in Dy2 LuN@C80 are close to zero. Analysis of the low-frequency molecular and lattice vibrations showed strong mixing of the lattice modes and endohedral cluster librations in k-space. This mixing simplifies the spin-lattice relaxation by conserving the momentum during the spin flip and helping to distribute the moment and energy further into the lattice.

Luminescence and X-ray Absorption Properties of Uniform Eu3+:(H3O)Lu3F10 Nanoprobes

Due to the high atomic number of lutetium and the low phonon energy of the fluoride matrix, Lu-based fluoride nanoparticles doped with active lanthanide ions are potential candidates as bioprobes in both X-ray computed tomography and luminescent imaging. This paper shows a method for the fabrication of uniform, water-dispersible Eu³⁺:(H₃O)Lu₃F₁₀ nanoparticles doped with different Eu contents. Their luminescent properties were studied by means of excitation and emission spectra as well as decay curves. The X-ray attenuation capacity of the phosphor showing the highest emission intensity was subsequently analyzed and compared with a commercial contrast agent. The results indicated that the 10% Eu³⁺-doped (H₃O)Lu₃F₁₀ nanoparticles fabricated with the proposed polyol-based method are good candidates to be used as dual probes for luminescent imaging and X-ray computed tomography.

Gallium Methylene

Despite the eminent importance of metal alkylidene species for organic synthesis and industrial catalytic processes, molecular homoleptic metal methylene compounds [M(CH₂ )_n ] as the simplest representatives, have remained elusive. Reports on this topic date back to 1955 when polymeric [Li₂ (CH₂ )]_n and [Mg(CH₂ )]_n were accessed by pyrolysis of methyllithium and dimethylmagnesium, respectively. However, the insoluble salt-like composition of these compounds has impeded their application as valuable reagents. We report that rare-earth metallocene methyl complexes [(C₅ Me₅ )₂ Ln{(μ-Me)₂ GaMe₂ }] (Ln=Lu, Y) trigger the formation of homoleptic gallium methylene [Ga₈ (μ-CH₂ )₁₂ ] from trimethylgallium [GaMe₃ ] (Me=methyl) via a cascade C-H bond activation involving the dodecametallic clusters [(C₅ Me₅ )₆ Ln₃ (μ₃ -CH₂ )₆ Ga₉ (μ-CH₂ )₉ ] as crucial intermediates. Such gallium methylene compounds feature a reversible [Ga₈ (μ-CH₂ )₁₂ ]/[Ga₆ (μ-CH₂ )₉ ] oligomer switch in donor solvents and act as Schrock-type methylene-transfer reagents.

Neuroendocrine Tumor Therapy with Lutetium-177: A Literature Review

The worldwide incidence of neuroendocrine tumors (NETs) has been increasing. They are a very diverse group of tumors which are commonly found in the gastrointestinal and bronchopulmonary tracts. These tumors usually express somatostatin receptors. Therefore, somatostatin analogs are used for symptom relief as well as treatment. Of the many therapeutic options available, peptide receptor radionuclide therapy (PRRT) has been shown to be very promising. In January 2018, the Food Drug and Authority (FDA) approved ¹⁷⁷Lu-Dotatate for use in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Lutetium is a lower energy beta-emitting radionuclide. The therapeutic use of lutetium-¹⁷⁷ (¹⁷⁷Lu) has shown better results in advanced gastroenteropancreatic and bronchial neuroendocrine tumors when compared with other therapies available. Adverse effects associated with this therapy include myelotoxicity and nephrotoxicity as the radiopeptides are reabsorbed and accumulate in the renal interstitium. Everolimus is a good and safe option in patients pretreated with ¹⁷⁷Lu-Dotatate. Lutetium, in combination with somatostatin analogs, has proven efficacy to treat gastroenteropancreatic neuroendocrine tumors in candidates with somatostatin receptor-positive advanced tumors and normal renal function. This therapy has great potential as it decreases tumor size, improves symptoms, and improves quality of life.

Clinical Outcomes of 177Lu-PSMA Radioligand Therapy in Earlier and Later Phases of Metastatic Castration-Resistant Prostate Cancer Grouped by Previous Taxane Chemotherapy

¹⁷⁷Lu-labeled prostate-specific membrane antigen (PSMA) radioligand therapy using PSMA-617 and PSMA-I&T ligands (¹⁷⁷Lu-PRLT) is an emerging treatment in metastatic castration-resistant prostate cancer (mCRPC). This retrospective study evaluates clinical outcomes of ¹⁷⁷Lu-PRLT in earlier and later phases of mCRPC grouped by previous taxane chemotherapy. Methods: A retrospective analysis was performed on 167 patients with mCRPC who underwent ¹⁷⁷Lu-PRLT between March 2013 and December 2016. Patients were classified as either taxane chemotherapy pretreated (T-pretreated) or naïve (T-naïve) depending on whether they had received taxane-based chemotherapy prior to ¹⁷⁷Lu-PRLT. Clinical outcome for T-pretreated and T-naïve patients was assessed by overall survival (OS), radiographic progression-free survival, and prostate-specific antigen (PSA) response rate. Univariate and multivariable analyses were performed for both T-pretreated and T-naïve patients to determine predictors of outcome. Toxicity was categorized by the Common Terminology Criteria for Adverse Events (version 4.03). Results: Of the 167 patients treated with ¹⁷⁷Lu-PRLT, 83 were T-pretreated and 84 were T-naïve. At baseline, T-pretreated patients had overall poorer performance status, a higher prevalence of bone metastases, higher PSA levels, lower hemoglobin levels, higher alkaline phosphatase (ALP) levels and had received more additional therapies compared with T-naïve patients. Median OS was 10.7 mo for T-pretreated patients and 27.1 mo for T-naïve patients. Median radiographic progression-free survival was 6.0 mo for T-pretreated patients and 8.8 mo for T-naïve patients. PSA response assessment was evaluable in 132 patients and seen in 25 of 62 (40%) T-pretreated patients and 40 of 70 (57%) T-naïve patients. Significant determinates of inferior OS in multivariable analysis for T-pretreated patients were poorer performance status, lower cumulative administered activity, and lower baseline hemoglobin. Higher baseline alkaline phosphatase was the only significant determinate of inferior OS in multivariable analysis for T-naïve patients. Overall ¹⁷⁷Lu-PRLT was safe, with minimal adverse effects evident during follow-up in both T-pretreated and T-naïve patients. Conclusion: ¹⁷⁷Lu-PRLT is a promising therapy in mCRPC, with encouraging outcomes and minimal associated toxicity seen in both our T-naïve and heavily pretreated patient cohorts.

Crystal structure and catalytic activity of tetra-kis-(μ2-ethyl 2,6-di-tert-butyl-4-methyl-phenyl phos-phato-κ2O:O')bis-(ethyl 2,6-di-tert-butyl-4-methyl-phenyl phosphato-κ2O,O')dilutetium n-heptane disolvate

The title complex, [Lu2(C17H28O4P)6]·2C7H16, was formed in the reaction between potassium 2,6-di-tert-butyl-4-methyl-phenyl ethyl phosphate, [K(2,6- t Bu2-4-MeC6H2-O)(EtO)PO2], and LuCl3(H2O)6 in water, followed by vacuum drying and recrystallization from heptane. Its crystal structure has triclinic (P [Formula: see text]) symmetry at 120 K. The lutetium tris-(phosphate) complex has a binuclear [Lu2(μ-OPO)4] core and the organophosphate ligand exhibits κ2O,O' terminal and μ2-κ1O:κ1O' bridging coordination modes with the LuIII ion being sixfold coordinated. The complex is of inter-est as a precatalyst in the acrylo-nitrile polymerization process and displays good catalytic activity under mild conditions.

Crystal structure of tri-benzyl-bis-(tetra-hydro-furan-κO)lutetium(III)

In the title compound, [Lu(C7H7)3(C4H8O)2] (1), the Lu ion is coordinated by three benzyl and two tetra-hydro-furan ligands. Two of the benzyl groups are bonded in a classical η1-fashion through the methyl-ene via the ipso-carbon atom of the benzyl ligand in addition to bonding through the methyl-ene C atom, resulting in a modified trigonal-bipyramidal coordination geometry about the Lu center.

Update on radionuclide therapy in oncology

Unstable isotopes and their capacity to emit ionizing radiation have been employed in clinical practice not only for diagnostic, but also for therapeutic purposes, with significant contribution in several fields of medicine and primarily in the management of oncologic patients. Their efficacy is associated with their ability to provide the targeted delivery of ionizing radiation for a determined duration. These compounds can be used for curative or palliative treatment, as well as for a diagnostic-therapeutic (theranostic) approach. This review summarises the most recent trends in radionuclide treatment for several malignancies, including prostate cancer, neuroendocrine tumours, and hematological and thyroid malignancies, in which radionuclide-based therapies have been employed with high effectiveness.

Isomorphous rare-earth bis[bis(2,6-diisopropylphenyl)phosphate] complexes and their self-assembly into two-dimensional frameworks by intramolecular hydrogen bonds

The crystal structures of rare-earth diaryl- or dialkylphosphate derivatives are poorly explored. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]chloridotetrakis(methanol-κO)neodymium methanol disolvate, [Nd(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (1), and of the lutetium, [Lu(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (2), and yttrium, [Y(C₂₄H₃₄O₄P)Cl(CH₄O)₄]·2CH₃OH, (3), analogues have been obtained by reactions between lithium bis(2,6-diisopropylphenyl)phosphate and LnCl₃(H₂O)₆ (in a 2:1 ratio) in methanol. Compounds (1)-(3) crystallize in the C2/c space group. Their crystal structures are isomorphous. The molecule possesses C₂ symmetry with a twofold crystallographic axis passing through the Ln and Cl atoms. The bis(2,6-diisopropylphenyl)phosphate ligands all display a κ¹O-monodentate coordination mode. The coordination polyhedron for the metal atom [coordination number (CN) = 7] is a distorted pentagonal bipyramid. Each [Ln{O₂P(O-2,6-ⁱPr₂C₆H₃)₂}₂Cl(CH₃OH)₄] molecular unit exhibits two intramolecular O-H...O hydrogen bonds, forming six-membered rings, and two intramolecular O-H...Cl interactions, forming four-membered rings. Intermolecular O-H...O hydrogen bonds connect each unit via four noncoordinating methanol molecules with four other units, forming a two-dimensional hydrogen-bond network. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]tetrakis(methanol-κO)(nitrato-κ²O,O')neodymium methanol disolvate, [Nd(C₂₄H₃₄O₄P)(NO₃)(CH₄O)₄]·2CH₃OH, (4), have been obtained in an analogous manner from NdCl₃(H₂O)₆. Compound (4) also crystalizes in the C2/c space group. Its crystal structure is similar to those of (1)-(3). The κ²O,O'-bidentate nitrate anion is disordered over a twofold axis, being located nearly on it. Half of the molecule is crystallographically unique (CN_Nd = 8). Unlike (1)-(3), complex (4) exhibits disorder of all three methanol molecules, one isopropyl group of the phosphate ligand and the NO₃^- ligand. The structure of (4) displays intra- and intermolecular O-H...O hydrogen bonds similar to those in (1)-(3). Compounds (1)-(4) represent the first reported mononuclear bis[bis(diaryl/dialkyl)phosphate] rare-earth complexes.

177Lu-PSMA Radioligand Therapy for Prostate Cancer

¹⁷⁷Lu-prostate-specific membrane antigen (PSMA) radioligand therapy (RLT) using inhibitors of PSMA is a novel therapeutic option in patients with metastatic castration-resistant prostate cancer. The current literature suggests that this therapy is well tolerated and effective. On the basis of clinical need and current evidence, the therapy is being implemented in a growing number of centers worldwide. Here, we review important aspects of ¹⁷⁷Lu-PSMA RLT, including patient stratification, the therapy protocol, concomitant medication, and follow-up, to inform medical staff involved in the RLT and care of patients with metastatic castration-resistant prostate cancer.

Peptide Receptor Radionuclide and Octreotide: A Novel Approach for Metastatic Tumor-Induced Osteomalacia

Key Messages:

Octreotide can be used as an adjunctive therapy to increase phosphorus levels in patients with tumor-induced osteomalacia. Malignant phosphaturic mesenchymal tumor (PMT) may benefit from treatment with peptide receptor radionucleotide therapy.

Context:

The success of treatment modalities for malignant PMT is limited. Octreotide has been used to treat hypophosphatemia in patients with tumor-induced osteomalacia with equivocal results. To our knowledge, there are no reports of octreotide or peptide receptor radionuclide therapy use for malignant PMT.

Case Description:

We report a 40-year-old man having hypophosphatemia, phosphaturia (tubular maximum of phosphorus corrected for glomerular filtration rate of <2.5 mg/dL), and somatostatin avid lesions in the right foot region with metastasis to both lungs. The patient had been subjected to resection of the primary tumor from the foot with thoracoscopic removal of the lung secondaries. Histology from all three lesions showed a spindle cell soft tissue tumor with a high mitotic index and somatostatin receptor 2 and 5 positivity. A trial of subcutaneous octreotide therapy at a dose of 100 μg thrice daily resulted in an increase in serum phosphorus levels from an average of 1.44 mg/dL to an average of 2.3 mg/dL. Finally, the affected limb was amputated, and the hypophosphatemia persisted postoperatively. In view of persistent hypophosphatemia and transient response to octreotide, the patient was administered four cycles of peptide receptor radionuclide therapy using ¹⁷⁷Lutetium, which showed moderate improvement of serum phosphorus levels.

Conclusion:

Although octreotide use has been reported in four patients with benign PMT, to our knowledge, this is the first case of malignant PMT that has used peptide receptor radionuclide therapy in the treatment of malignant PMT. This moderately beneficial evidence is likely to guide the future use of radionuclide treatments in such tumors.

Preliminary experience with dosimetry, response and patient reported outcome after 177Lu-PSMA-617 therapy for metastatic castration-resistant prostate cancer

Prostate cancer can be targeted by ligands to the prostate-specific membrane antigen (PSMA). We aimed to evaluate dosimetry, safety and efficacy of 177Lu-PSMA-617 radioligand therapy (RLT) in patients with metastatic castration-resistant prostate cancer (mCRPC).Fifteen patients each received two cycles of 3.7 GBq (n = 5) or 6.0 GBq (n = 10) 177Lu-PSMA-617 at an eight to ten weeks interval. For safety monitoring, each treatment was followed by dosimetry with serial quantitative SPECT as well as inpatient and outpatient recording of adverse events. Response to RLT was primarily determined by baseline to follow-up change in 68Ga-PSMA PET/CT (RECIST1.1), as well as change in prostate-specific antigen (PSA), quality of life (QoL, FACT-P scale), and pain (Brief Pain Inventory) as secondary endpoints.Radiation dose delivered to the tumor (6.1 Gy/GBq) was six to twelve-fold higher than to critical organs (kidney left/right 0.5/0.6 Gy/GBq each, salivary glands 1.0 Gy/GBq). Total radiation dose per kidney did not exceed 23 Gy in any patient. Three patients had sub-acute and latent grade 3 events, i.e. anemia, leukocytopenia, and nausea. No acute events, grade ≥4 events or high grade events for salivary gland or kidney function were observed. After two RLT cycles, 4 (27%) patients had partial response, 6 (40%) had stable disease, and 5 (33%) had progressive disease according to RECIST. Any PSA decline was observed in 12/15 (80%) patients during RLT. Significant pain relief was documented in 7/10 (70%) symptomatic patients and QoL improved in 9/15 (60%) patients.177Lu-PSMA-617 therapy proved safe and indicated promising response rates for both objective and patient-reported outcomes in our small group of mCRPC patients.

[177Lu-PSMA-617 therapy, dosimetry and follow-up in patients with metastatic castration-resistant prostate cancer]

Radioligand therapy (RLT) using 177Lu labelled inhibitors of the prostate-specific membrane antigen (177Lu-PSMA) is performed in patients with metastatic castration-resistant prostate cancer (mCRPC) after exhaustion of other options. German University Clinics offer RLT since 2013 on a compassionate use basis. The present consensus document includes recommendations for RLT with 177Lu-PSMA-617. These consensus statements were developed by an expert panel formed by the German Society of Nuclear Medicine (DGN) in December 2015. Statements include recommendations for indication, baseline tests, therapy protocol, concomitant therapy, dosimetry, and follow-up. Consensus recommendations aim to inform the attending medical staff, standardize 177Lu-PSMA-617 RLT, and improve quality of individual patient care.

Phase and Size Control of Core-Shell Upconversion Nanocrystals Light up Deep Dual Luminescence Imaging and CT In Vivo

Upconversion nanocrystals (UCNCs) have recently been explored as optical imaging nanoprobes. However, conventional β-NaLuF4 (-) based UCNCs often suffer from large particle size and weak upconversion luminescence (UCL) intensity, leading to poor biocompatibility and low detection sensitivity. Here, a novel strategy for controlling the crystalline phase and size of UCNCs has been developed by doping of yttrium ions, resulting in particle size reduction and phase transition. The total UCL intensity of prepared core-shell UCNCs is significantly enhanced up to ≈4.9 and ≈17.4 times after Tm(3+) and Er(3+) doping than that of core UCNCs, offering deeper tissue UCL imaging with a depth of 8 mm in vivo. Moreover, the CT signal of core-shell UCNCs is ≈1.5 and ≈3.5 times brighter than that of core UCNCs and commercial ioversol agent because of increasing contents of Lu(3+) doped in UCNCs. The synthesized core-shell UCNCs hold a great promise in deep UCL and CT dual-modality imaging in vitro and in vivo.

Towards Clarifying the Role of O2 during the Phthalocyanine Synthesis

The role of O2 within the synthesis of phthalocyanines (Pcs) has remained unclear in the past century. Here, we demonstrate that O2 , in cooperation with the solvent n-pentanol, participates in the cyclic tetramerization of phthalonitriles over the half-sandwich complex template [Lu(Pc)(acac)] (acac=acetylacetonate) and terminates the reaction at the stage of uncyclized isoindole oligomeric derivatives rather than the phthalocyanine chromophores, resulting in the isolation of the heteroleptic (phthalocyaninato)(triisoindole-1-one) lutetium double-decker complexes [(Pc)Lu(TIO-I)] (TIO-I=3,4,7,8,11,12-sexi(2,6-diisopropylphenoxy)-15-[4,5-di(2,6-diisopropylphenoxy)-2-cyanobenzimidamido]triisoindole-1-one) and [(Pc)Lu(TIO-II)] (TIO-II=3,4,7,8,11,12-sexi(2,6-dimethylphenoxy)-15-[4,5-di(2,6-dimethylphenoxy)-2-cyanobenzimidamido]triisoindole-1-one) with the help of bulky substituents at the phthalonitrile periphery and an unsubstituted phthalocyanine ligand in the double-decker skeleton. Nevertheless, the cyclic tetramerization of the phthalonitriles was revealed to be sensitive to O2 with the reaction progression also depending on the oxygen concentration/content, leading to the O2 -senstive and -dependent nature for the isolation of phthalocyanine derivatives.

Survival after somatostatin based radiopeptide therapy with (90)Y-DOTATOC vs. (90)Y-DOTATOC plus (177)Lu-DOTATOC in metastasized gastrinoma

We aimed to explore the effects of (90)Y-DOTATOC and (90)Y-DOTATOC plus (177)Lu-DOTATOC on survival of patients with metastasized gastrinoma. Patients with progressive metastasized gastrinoma were treated with repeated cycles of (90)Y-DOTATOC or with cycles alternating between (90)Y-DOTATOC and (177)Lu-DOTATOC until tumor progression or permanent toxicity. Multivariable Cox regression analyses were used to study predictors of survival. A total of 36 patients were enrolled; 30 patients received (90)Y-DOTATOC (median activity per patient 11.8GBq; range: 6.1-62.2GBq) and 6 patients received (90)Y-DOTATOC plus (177)Lu-DOTATOC (median activity per patient: 14.8GBq; range: 7.4-14.8GBq). Response was found in 26 patients (72.2%), including morphological (n=12, 33.3%), biochemical (n=14, 38.9%) and/or clinical response (n=6, 16.2%). A total of 21 patients (58.3%) experienced hematotoxicity grade 1/2, while 1 patient (2.8%) experienced hematotoxicity grade 3; no grade 4 hematotoxicity occurred. Furthermore, 2 patients (5.6%) developed grade 4 renal toxicity; no grade 5 renal toxicity occurred. Responders had a significantly longer median survival from time of enrollment than non-responders (45.1 months, range: 37.1-53.1 months vs. 12.6 months, range: 11.0-14.2, hazard ratio: 0.12 (0.027-0.52), p=0.005). Additionally, there was a trend towards longer median survival with (90)Y-DOTATOC plus (177)Lu-DOTATOC as compared to (90)Y-DOTATOC alone (60.2 months, range: 19.8-100.6 months vs. 27.0 months, range: 4.0-50.0, hazard ratio: 0.21 (0.01-3.98), p=0.16). Response to (90)Y-DOTATOC and (90)Y-DOTATOC plus (177)Lu-DOTATOC therapy is associated with a longer survival in patients with metastasized gastrinoma. Both treatment regimens are promising tools for management of progressive gastrinoma.

Metal-size influence in iso-selective lactide polymerization

Iso-selective initiators for the ring-opening polymerization (ROP) of rac-lactide are rare outside of Group 13. We describe the first examples of highly iso-selective lutetium initiators. The phosphasalen lutetium ethoxide complex shows excellent iso-selectivity, with a P(i) value of 0.81-0.84 at 298 K, excellent rates, and high degrees of polymerization control. Conversely, the corresponding La derivative exhibits moderate heteroselectivity (P(s)=0.74, 298 K). Thus, the choice of metal center is shown to be crucial in determining the level and mode of stereocontrol. The relative order of rates for the series of complexes is inversely related to metallic covalent radius: that is, La>Y>Lu.

Upconversion nanophosphors Naluf₄:Yb,Tm for lymphatic imaging in vivo by real-time upconversion luminescence imaging under ambient light and high-resolution X-ray CT

Lanthanide upconversion nanophosphor (UCNP) has attracted increasing attention for potential applications in bioimaging due to its excellence in deep and high contrast imaging. To date, most upconversion imaging applications were demonstrated in dark surroundings without ambient light for higher signal-to-noise ratio, which hindered the application of optical imaging guided surgery. Herein, the new established NaLuF₄-based UCNP (NaLuF₄:Yb,Tm, ~17 nm) with bright upconversion emission around 800 nm as imaging signal was used to realize imaging under ambient light to provide more convenient for clinician. Moreover, due to the existance of heavy element lutetium (Lu) in the host lattice, the NaLuF₄:Yb,Tm nanoparticles can also be used as an X-ray CT imaging agent to enhance the imaging depth and in vivo imaging resolution.