Development of a Single Vial Kit Solution for Radiolabeling of 68Ga-DKFZ-PSMA-11 and Its Performance in Prostate Cancer Patients.

Prostate-specific membrane antigen (PSMA), a type II glycoprotein, is highly expressed in almost all prostate cancers. By playing such a universal role in the disease, PSMA provides a target for diagnostic imaging of prostate cancer using positron emission tomography/computed tomography (PET/CT). The PSMA-targeting ligand Glu-NH-CO-NH-Lys-(Ahx)-HBED-CC (DKFZ-PSMA-11) has superior imaging properties and allows for highly-specific complexation of the generator-based radioisotope Gallium-68 ((68)Ga). However, only module-based radiolabeling procedures are currently available. This study intended to develop a single vial kit solution to radiolabel buffered DKFZ-PSMA-11 with (68)Ga. A (68)Ge/(68)Ga-generator was utilized to yield (68)GaCl3 and major aspects of the kit development were assessed, such as radiolabeling performance, quality assurance, and stability. The final product was injected into patients with prostate cancer for PET/CT imaging and the kit performance was evaluated on the basis of the expected biodistribution, lesion detection, and dose optimization. Kits containing 5 nmol DKFZ-PSMA-11 showed rapid, quantitative (68)Ga-complexation and all quality measurements met the release criteria for human application. The increased precursor content did not compromise the ability of (68)Ga-DKFZ-PSMA-11 PET/CT to detect primary prostate cancer and its advanced lymphatic- and metastatic lesions. The (68)Ga-DKFZ-PSMA-11 kit is a robust, ready-to-use diagnostic agent in prostate cancer with high diagnostic performance.

Production of high specific activity (195m) Pt-cisplatinum at South African Nuclear Energy Corporation for Phase 0 clinical trials in healthy individual subjects.

Platinum agents continue to be the main chemotherapeutic agents used in the first-line and second-line treatments of cancer patients. It is important to fully understand the biological profile of these compounds in order to optimize the dose given to each patient. In a joint project with the Australian Nuclear Science and Technology Organisation and the Nuclear Medicine Department at Steve Biko Academic Hospital, South African Nuclear Energy Corporation synthesized and supplied (195m) Pt-cisplatinum (commonly referred to as cisplatin) for a clinical pilot study on healthy volunteers. Enriched (194) PtCl2 was prepared by digestion of enriched (194) Pt metal (>95%) followed by thermal decomposition over a 3 h period. The (194) PtCl2 was then placed in a quartz ampoule, was irradiated in SAFARI-1 up to 200 h, then decay cooled for a minimum of 34 h prior to synthesis of final product. (195m) Pt(NH3 )2 I2 , formed with the addition of KI and NH4 OH, was converted to the diaqua species [(195m) Pt(NH3 )2 (H2 O)2 ](2+) by reaction with AgNO3 . The conversion to (195m) Pt-cisplatinum was completed by the addition of concentrated HCl. The final product yield was 51.7% ± 5.2% (n = 5). The chemical and radionuclidic purity in each case was >95%. The use of a high flux reactor position affords a higher specific activity product (15.9 ± 2.5 MBq/mg at end of synthesis) than previously found (5 MBq/mg). Volunteers received between 108 and 126 MBq of radioactivity, which is equivalent to 6.8-10.0 mg of carrier cisplatinum. Such high specific activities afforded a significant reduction (~50%) in the chemical dose of a carrier cisplatinum, which represents less than 10% of a typical chemotherapeutic dose given to patients. A good manufacturing practice GMP compliant product was produced and was administered to 10 healthy volunteers as part of an ethically approved Phase 0 clinical trial. The majority of the injected activity 27.5% ± 5.8% was excreted in the urine within 5 h post injection (p.i.). Only 8.5% ± 3.1% of cisplatinum remained in blood pools at 5 h, which gradually cleared over the 6-day monitoring period p.i. At the end of the study (6 days p.i.), a total of 37.4% ± 5.3% of the product had cleared from the blood into urine, and approximately 63% remained in the body. The significantly lower concentration of carrier cisplatinum used for imaging resulted in a well-tolerated product.

Evaluation of a Flexible NOTA-RGD Kit Solution Using Gallium-68 from Different 68Ge/68Ga-Generators: Pharmacokinetics and Biodistribution in Nonhuman Primates and Demonstration of Solitary Pulmonary Nodule Imaging in Humans.

PURPOSE: Radiopharmaceuticals containing the motive tripeptide arginyl-glycyl-asparatic acid (RGD) are known to target ανß3 integrins during tumor angiogenesis. A more generic kit radiolabeling procedure accommodating Ga-68 from different generators was developed for NOTA-RGD and evaluated for its versatile use and safety in subsequent in vivo applications. The [68Ga]NOTA-RGD kit was further verified for its expected biodistribution and pharmacokinetics in nonhuman primates and its clinical sensitivity to detect solitary pulmonary nodules (SPN) in cancer patients. PROCEDURES: Single vial kits containing 28-56 nmol of NOTA-cyclo-Arg-Gly-Asp-d-Tyr-Lys (NOTA-RGD) and sodium acetate trihydrate buffer were formulated. Versatility of the NOTA-RGD radiolabeling performance and adaption to a TiO2- and a SnO2-based generator type, characterization and long-term storage stability of the kits were carried out. The blood clearance and urine recovery kinetics as well as the image-guided biodistribution of [68Ga]NOTA-RGD was studied in a vervet monkey model. [68Ga]NOTA-RGD kits were further tested clinically to target solitary pulmonary nodules. RESULTS: The kits could be successfully formulated warranting integrity over 3-4 months with a good [68Ga]NOTA-RGD radiolabeling performance (radiochemical purity >95 %, decay corrected yield 76-94 %, specific activity of 8.8-37.9 GBq/µmol) The kits met all quality requirements to be further tested in vivo. [68Ga]NOTA-RGD cleared rapidly from blood and was majorly excreted via the renal route. The liver, spleen, heart and intestines showed initial uptake with steadily declining tissue activity concentration over time. In addition, the [68Ga]NOTA-RGD kit allowed for delineation of SPN from non-malignant lung tissue in humans. CONCLUSIONS: A more versatile radiolabeling procedure using kit-formulated NOTA-RGD and different generator types was achieved. The uncompromised in vivo behavior and efficient targeting of SPN warrants further investigations on the clinical relevance of [68Ga]NOTA-RGD derivatives to implement initial guidelines and management of patients, with regard to integrin targeted imaging.

Blood plasma model predictions for the proposed bone-seeking radiopharmaceutical [(117m)Sn]Sn(IV)-N,N',N'-trimethylenephosphonate-poly(ethyleneimine).

In an attempt to elucidate the in vivo stability of the prospective radiopharmaceutical [(117m)Sn]Sn(IV)-PEI-MP, where PEI-MP stands for N,N',N'-trimethylenephosphonate-polyethyleneimine, glass electrode potentiometry was used to determine the stability constants of the Sn(4+) ion as complexed with a variety of physiological amino acids. In addition, linear free energy relationship (LFER) correlation plots were used to extrapolate the constants of the major blood plasma ligands, based on data from Cu(2+), Pb(2+), and Zn(2+). In so doing, a thermodynamic model of blood plasma was established for Sn(4+) from which the complexation tendencies of Sn(4+) were predicted in the event of the intravenous administration of such a drug. It was found that the Sn(IV)-PEI-MP could succumb to competition by the glutamine amino acid, which forms more stable complex(es), whilst the PEI-MP gets taken up largely by Ca(2+). Also, this study shows the value of the in vitro experiments and modeling performed for radiopharmaceutical research and for attempts to reduce the number of animal experiments.