Increased amino acid transport in gliomas allows imaging of metabolically active tumor volume by PET. Tryptophan analog PET radiotracers can provide additional information by tracking tumoral metabolism via the upregulated immunosuppressive tryptophan-kynurenine pathway. We tested the recently developed tryptophan analog PET tracer [18F]-fluoro-ethyl-L-tryptophan ([18F]FETrp) for detecting post-treatment glioblastoma while using a non-invasive approach to generate parametric tryptophan metabolic maps and comparing them with static tracer uptake maps and contrast-enhanced MRI. Five patients (age: 22–67 years) with previously treated glioblastoma underwent [18F]FETrp PET/CT imaging. A dynamic acquisition protocol sampled the brain and blood pool non-invasively using the FlowMotion Multiparametric PET software (Siemens Healthineers). Parametric brain images of the unidirectional uptake rate constant (Ki), characterizing irreversible tryptophan trapping and the volume of distribution (VD) were fused with static uptake (SUV) maps and contrast-enhanced brain MRI. Voxels with elevated Ki, VD, and SUV were defined, and their spatial associations with contrast-enhanced volumes were characterized by their

Increased amino acid transport in gliomas allows imaging of metabolically active tumor volume by PET. Tryptophan analog PET radiotracers can provide additional information by tracking tumoral metabolism via the upregulated immunosuppressive tryptophan-kynurenine pathway. We tested the clinically feasible tryptophan analog PET tracer [18]F-fluoro-ethyl-L-tryptophan ([18]FETrp) for detecting post-treatment glioblastoma infiltration while using a non-invasive approach to generate parametric tryptophan metabolic maps and comparing them with static tracer uptake maps and contrast-enhanced MRI. Five patients (age: 22-67 years) with previously treated glioblastoma showing MRI signs of tumor progression underwent [18]FETrp PET imaging. A dynamic acquisition protocol was applied to sample the brain and blood pool non-invasively using the FlowMotion Multiparametric PET software (Siemens Healthineers). Parametric brain images of the unidirectional uptake rate constant (Ki), characterizing irreversible tryptophan trapping, were fused with static uptake maps and contrast-enhanced brain MRI. Voxels with elevated Ki and uptake values were defined (>2SD above mean values in contralateral normal brain), and their spatial association with contrast-enhanced volumes was characterized by their % volume overlap and the distance between their centroids. A substantial spatial volume overlap of 66±12% (average centroid distance: 5mm) was observed between MRI contrast-enhancing regions and elevated static [18]FETrp uptake. The overlap between contrast-enhancing regions and elevated Ki metabolic volumes was lower (6±5%, p<0.001), with increased Ki areas extending deeper into non-enhancing brain (12mm average spatial separation). These non-enhancing areas with high Ki values showed new contrast-enhancement on subsequent MRI, consistent with tumor progression. Areas of high tryptophan metabolism detected by [18]FETrp PET-derived parametric maps extend outside the contrast-enhancing glioblastoma mass in adjacent non-enhancing brain regions that can be missed or underestimated by static uptake images. [18]FETrp PET metabolic maps have the potential for enhanced detection of non-enhancing glioma infiltration for improved treatment targeting.

Colony-stimulating factor 1 receptor (CSF1R) is almost exclusively expressed on microglia in the human brain and thus, has promise as a biomarker for imaging microglia density as a proxy for neuroinflammation. [C-11]CPPC is a radiotracer with selective affinity to CSF1R, and has been evaluated for in-human microglia PET imaging. The flourine-18 labeled CPPC derivative, 5-cyano-N-(4-(4-(2-[F-18]fluoroethyl)piperazin-1-yl)-2-(piperidin-1-yl)phenyl)furan-2-carboxamide ([F-18]FCPPC), was previously synthesized, however, with a low radiochemical yield using manual radiosynthesis. In this work, we report a fully automated radiosynthesis of [F-18]FCPPC on a Synthra RNplus research module. In a total synthesis time of 50 min, [F-18]FCPPC was obtained in decay corrected radiochemical yields of 26.8 +/- 0.1% (n = 3) with >99% radiochemical purities. Quality control testing showed that [F-18]FCPPC met all release criteria. In sum, we report the first fully automated radiosynthesis of [F-18]FCPPC, a promising radiopharmaceutical for imaging microglia in humans.

The macrophage colony-stimulating factor 1 receptor (CSF1R) is almost exclusively expressed in microglia, representing a biovivo PET imaging of microglia. However, previous studies reported a low radiochemical yield, motivating additional research to optimize [C-11]CPPC radiochemistry. In this work, we report an automated radiosynthesis of [C-11]CPPC on a Synthra MeIPlus module with improved radiochemical yield. The final [C-11]CPPC product was obtained with excellent chemical/radiochemical purities and molecular activity, facilitating high-quality in-human PET imaging applications.

Purpose. Preclinical studies showed the tryptophan analog PET radiotracer 1-(2- 18 F-fluoroethyl)-L-tryptophan ( 18 F-FETrp) to accumulate in various tumors, including gliomas, and being metabolized via the immunosuppressive kynurenine pathway. In this first-in-human study, we tested the use 18 F-FETrp-PET in patients with neuroendocrine and brain tumors. Procedures . We applied dynamic brain imaging in patients with gliomas (n = 2) and multi-pass 3D whole-body PET scans in patients with neuroendocrine tumors (n =4). Semiquantitative analysis of organ and tumor tracer uptake was performed using standardized uptake values (SUVs). In addition, organ dosimetry was performed based on extracted time-activity curves and the OLINDA software. Results . Neuroendocrine tumors showed an early peak (10-min post-injection) followed by washout. Both gliomas showed prolonged 18 F-FETrp accumulation plateauing around 40-min and showing heterogeneous uptake including non-enhancing tumor regions. Biodistribution showed moderate liver uptake and fast clearance of radioactivity into the urinary bladder; the estimated effective doses were similar to other 18 F-labeled radioligands. Conclusions . The study provides proof-of-principle data for the safety and potential clinical value of 18 F-FETrp-PET for molecular imaging of human gliomas.

The cannabinoid subtype 1 receptor (CB1R) is highly expressed in the central nervous system and abnormalities in regional CB1R density are associated with neurodegenerative disorders. The PET tracer [18F]FMPEP-d2 is an inverse CB1R agonist which was shown to be suitable for non-invasive PET imaging. In this work, we reported the fully automated radiosynthesis of [18F]FMPEP-d2 on a Synthra RNplus research module. In a total synthesis time of 70 min, [18F]FMPEP-d2 was obtained in 2.2 ± 0.1 GBq (n = 3) with excellent radiochemical and chemical purity. Quality control test showed that [18F]FMPEP-d2 product meets all the release criteria for clinical patient use.

The radiotracer 1‐(2‐[18F]fluoroethyl)‐L‐tryptophan (L‐[18F]FETrp or [18F]FETrp) is a substrate of indoleamine 2,3‐dioxygenase, the initial and key enzyme of the kynurenine pathway associated with tumoral immune resistance. In preclinical positron emission tomography studies, [18F]FETrp is highly accumulated in a wide range of primary and metastatic cancers, such as lung cancer, prostate cancer, and gliomas. However, the clinical translation of this radiotracer into the first‐in‐human trial has not been reported, partially due to its racemization during radiofluorination which renders the purification of the final product challenging. However, efficient purification is essential for human studies in order to assure radiochemical and enantiomeric purity. In this work, we report a fully automated radiosynthesis of [18F]FETrp on a Synthra RNPlus research module, including a one‐pot two steps radiosynthesis, dual independent chiral and reverse‐phase semipreparative high‐performance liquid chromatography purifications, and solid‐phase extraction‐assisted formulation. The presented approach has led to its Investigational New Drug application and approval that allows the testing of this tracer in humans.

The radiotracer 1-(2-[18 F]fluoroethyl)-L-tryptophan (L-[18 F]FETrp or [18 F]FETrp) is a substrate of indoleamine 2,3-dioxygenase (IDO), the initial and key enzyme of the kynurenine pathway associated with tumoral immune resistance. In preclinical PET studies, [18 F]FETrp is highly accumulated in a wide range of primary and metastatic cancers, such as lung cancer, prostate cancer, and gliomas. However, the clinical translation of this radiotracer into the first-in-human trial has not been reported, partially due to its racemization during radiofluorination which renders the purification of the final product challenging. However, efficient purification is essential for human studies in order to assure radiochemical and enantiomeric purity. In this work, we report a fully automated radiosynthesis of [18 F]FETrp on a Synthra RNPlus research module, including a one-pot two steps radiosynthesis, dual independent chiral and reverse-phase semi-preparative HPLC purifications, and solid-phase extraction (SPE) assisted formulation. The presented approach has led to its Investigational New Drug (IND) application and approval that allows the testing of this tracer in humans.

Radiotracer [18F]Flortaucipir is an FDA-approved diagnostic agent for PET imaging of density and distribution of abnormal tau protein deposition (tauopathies) in Alzheimer's disease. A high-yield automated method for routine GMP-compliant [18F]Flortaucipir production is desired to meet increasing clinical need. In this work, we reported an automated radiosynthesis of [18F]Flortaucipir in a RNplus Research module and the quality control (QC) tests for human use under full GMP compliance. Briefly, automated radiosynthesis of [18F]Flortaucipir was processed via nucleophilic radiofluorination of precursor AV1622 and followed by acid hydrolysis in a RNplus Research module, which included the radiosynthesis, semi-preparative high-performance liquid chromatography (HPLC) purification, and the final formulation via solid phase extraction (SPE). The final products were obtained in non-decay corrected radiochemical yields of 14.8-16.6% (n = 3) within total synthesis time of 55 min. The radiochemical purities of [18F]Flortaucipir were > 99.9% and the molar activities were 247.9-384.8 GBq/µmol at end of synthesis. The results of QC tests met all the specifications for human use. In conclusion, [18F]Flortaucipir was reproducibly achieved with desired radiochemical yield and high radiochemical purity and molar activity. Three GMP compliant validation runs and QC results demonstrated the efficacy of this method for automated production of [18F]Flortaucipir for human use.

A single HPIC method was developed and validated for the analysis of both [11C]Choline and [13N]Ammonia with the same setup. The HPIC system suitability tests were performed and [11C]Choline and [13N]Ammonia were used to verify their performance on this HPIC method. The HPIC setup and method provides qualitative and quantitative analysis information of [11C]Choline and [13N]Ammonia. The data suggested this HPIC method is validated for determining radiochemical/chemical purity and radiochemical identity of [11C]Choline and [13N]Ammonia products in CGMP compliant manufacturing process.

Radiotracer 3,4-dihydroxy-6-[18F]fluoro-L-phenylalanine (L-6-[18F]fluorodopa or [18F]FDOPA) is widely used for PET imaging of dopamine metabolism in several diseases including Parkinson's Disease, brain tumor, neuroendocrine tumors, and focal hyperinsulinism of infancy. In 2019, [18F]FDOPA was approved by US FDA for detection of dopaminergic nerve terminals in the striatum of adult patients with suspected Parkinsonian Syndromes. A convenient and reliable method is desired for fully automated production of [18F]FDOPA under cGMP compliance to meet the increasing clinical need. In this study, we reported a cassette-based automated production of [18F]FDOPA using a GE Fastlab 2 module and the quality control (QC) under fully cGMP compliant environment. Briefly, automated radiosynthesis of [18F]FDOPA was processed via nucleophilic radio-fluorination using FDOPA Fastlab cassette and solid phase extraction (SPE) purification. The QC tests of [18F]FDOPA, including appearance, pH, half-life, radiochemical purity and identity, enantiomeric purity, chemical impurities, molecular activity, radioactive concentration, filter integrity, endotoxin, and sterility, were conducted at the end of synthesis (EOS) and 8 h after EOS during the validation runs. Three consecutive productions of [18F]FDOPA were reliably achieved with desired radiochemical yield and high radiochemical/enantiomeric purities and molar activity. The uncorrected radiochemical yields of [18F]FDOPA were 9.3-9.8% with a total synthesis time of ~140 min. Both radiochemical and enantiomeric purities of [18F]FDOPA were >99.9% and the molar activities were 2.1-3.9 Ci/μmole at EOS. The full QC results at EOS and 8 h after EOS showed that the produced [18F]FDOPA met all release criteria for clinical use within 8 hours of expiration time. Three consecutive validation runs and QC results demonstrated the efficacy of cassette-based production of [18F]FDOPA for routine clinical use.

1229 Introduction: Acetate is an important substrate for energy metabolism as well as an important component of cell membrane lipid synthesis. As a result, [11C]acetate is employed as a versatile noninvasive imaging agent in both oncology and cardiology. Here we report a facile radiosynthesis of [11C]acetate and application of this tracer to the measurement of myocardial blood flow (BF) and oxidative metabolism (MVO2) in a group of patients with dilated cardiomyopathy (DCM). Methods: [11C]Acetate was produced with the reaction of [11C]CO2 and methyl magnesium bromide and purified by distillation. Specifically, by proton bombardment of 1% oxygen and nitrogen through the 14N(p,a)11C in a GE PETtracer 860 cyclotron, [11C]CO2 was formed and bubbled through a chilled solution of 60 µL methyl magnesium bromide (3 M in diethyl ether) in 0.3 mL freshly distilled THF. The reaction mixture was quenched with 0.5 mL water and evaporated to dryness by heating at 140 °C. Followed by the addition of 0.5 mL 10% H3PO4, [11C]acetic acid was then flushed into a collecting vial containing 50 µL 8.4% NaHCO3 and 5 mL 0.9% NaCl, USP. The formulated [11C]acetate was passed through a 0.2 µm Millex-GS filter into a final product vial. A 0.5 mL sample was used for quality control. Dynamic PET imaging (30 min acquisition) was performed in 20 DCM patients following injection of 500 + 50MBq of tracer. Myocardial BF (K1 corrected for decreased extraction fraction) and MVO2 (k2) was determined based on a one-tissue compartmental model including blood volume correction (BV) and correction of the input function for recirculating CO2. In addition, the k2 parameter was compared with a mono-exponential fit of the initial data (4 - 12min, Kmono), used in clinical routine as an index of MVO2. Results: Using a total synthesis time of 20 min (5 min beam at 40 µA), [11C]acetate was obtained in the range of 5-7GBq at EOS. HPLC analysis demonstrated >90% radiochemical purities and excellent agreement with the acetate reference standard. MVO2 in coronary territories (LAD, RCA, LCX) was determined as 5.2+0.4, 4.9+0.3 and 5.4+0.3 ml/100g/min and BF was determined as 71+14, 68+12 and 73+14 ml/100g/min, respectively. Finally, although absolute values for Kmono were about 30% lower than k2 values, these two parameters showed an excellent correlation (R2 = 0.81). Conclusions: A facile radiosynthesis of [11C]acetate was achieved with desired radiochemical yield and radiochemical purity, making the assessment of myocardial oxidative metabolism (based on Kmono) feasible in clinical routine.

1202 Introduction: Radiotracer 3,4-dihydroxy-6-[18F]fluoro-L-phenylalanine ([18F]FDOPA) is widely used for PET imaging of dopamine metabolism in several diseases including Parkinson’s Disease, brain tumor, neuroendocrine tumors, and focal hyperinsulinism of infancy, especially, [18F]FDOPA has been approved by US FDA in 2019 for detection of dopaminergic nerve terminals in the striatum in adult patients with suspected Parkinsonian Syndromes. A high-yield automated method for routine GMP-compliant [18F]FDOPA production is desired to meet increasing clinical need. In this study, we reported a cassette-based automated production of [18F]FDOPA in GE Fastlab 2 module and the quality control testing under fully cGMP compliant environment. Methods: Automated production of [18F]FDOPA was processed via nucleophilic radio-fluorination using FDOPA cassette (ABX, Germany) and purified via solid phase extraction. Specifically, [18F]fluoride was delivered directly into the FASTlab unit, trapped on an anion exchange cartridge (QMA), eluted with TBAHCO3, and followed by azeotropic drying. Radiofluorination of the precursor in DMSO was achieved by heating at 130°C for 8 minutes to form intermediate compound, which was purified on a C18 EC cartridge, oxidized by m-CPBA oxidation, and hydrolyzed with 30% HCl. The yielded product was further purified via C18 Sep-Pak and HR-P cartridges separation. The [18F]FDOPA product was then eluted from the cartridges with a phosphate buffer solution, and passed through a WAX cartridge, a Light Alumina N cartridge and a sterilizing 0.22 µm filter into the product vial. The quality control (QC) tests of [18F]FDOPA, including appearance, pH, half-life, radiochemical purity and identity, enantiomeric purity, chemical impurities, molecular activity, radioactive concentration, filter integrity, endotoxin and sterility, were conducted at end of synthesis (EOS) and 8 h after EOS during the production validation runs. Results: Three consecutive batches of [18F]FDOPA were successfully completed within defined specifications. The uncorrected radiochemical yields of [18F]FDOPA were 9.3 - 9.8% with a total synthesis time of ~140 min. Both the radiochemical and enantiomeric purities of [18F]FDOPA were >99.9% and the molar activities were 2.1 - 3.9 Ci/µmole at EOS. The full QC results at EOS and 8h showed that the produced [18F]FDOPA met all the release criteria for clinical use within 8 hours of expiration time. Conclusions: The cassette-based productions of [18F]FDOPA were reliably achieved with desired radiochemical yield and high radiochemical/ enantiomeric purities and molar activity. Three production validation runs and QC results demonstrated the efficacy of method for routine clinical use.

1004 Introduction: (R)-[11C]PK11195 is a well-studied positron emission tomography (PET) radiotracer to image inflammation by targeting 18 kDa translocator protein (TSPO) expression. The production of (R)-[11C]PK11195 occurs via [11C]methyl iodide ([11C]CH3I) methylation of base-activated (R)-N-desmethyl-PK11195 followed by high performance liquid chromatography (HPLC) purification. In this study, we reported an improved production of (R)-[11C]PK11195 with reliable yield and facile HPLC purification. Methods: Sodium hydride (NaH, 60% in mineral oil, 3-5 mg) as a base was added to a solution of (R)-N-desmethyl-PK11195 (2 mg) in anhydrous DMSO (200 μL) at 3-5 min before end of beam (EOB). [11C]CH3I, synthesized from GE Tracerlab FX2MEI module, was delivered to the base-activated precursor solution in a reaction vessel of GE Tracerlab FX2M module. The resulting solution was maintained at room temperature (25 °C) for 1.5 minutes, followed by 1 mL HPLC eluent dilution, and then transferred to a semi-preparative HPLC column for separation. The (R)-[11C]PK11195 fraction was collected, diluted with 30 mL deionized water, and concentrated on a solid-phase extraction tC18 cartridge. Followed by washing with 10 mL sterile water, (R)-[11C]PK11195 was eluted with 1.5 mL ethanol from tC18 cartridge, reconstituted in 9 mL normal saline, and then passed through a sterile 0.22 µm filter into a product vial. A representative sample was withdrawn for clinical quality control tests. Results: (R)-[11C]PK11195 product was obtained in 138-170 mCi (5.1-6.3 GBq, n = 3) at end of synthesis (EOS). The total synthesis time was 33 min starting from EOB, and the typical C-11 target irradiation time was 30 min at 55 µA beam current. The (R)-[11C]PK11195 fraction was collected from 4.8-5.3 min on semi-preparative HPLC. The radiochemical yield was 10.6-12.7% (uncorrected, based on radioactivity of [11C]CH3I trapped in the reactor vessel and (R)-[11C]PK11195 in product vial). The radiochemical purity was >99% and the molecular activity was 3.14-4.15 Ci/µmol (116-154 GBq/µmol) at EOS. Final (R)-[11C]PK11195 product passed all the quality control tests according to current US Pharmacopeia and FDA cGMP acceptance criteria, including pH, filter integrity, residual solvents, endotoxin, sterility, radiochemical/chemical purity and radiochemical identity, and molecular activity. Conclusions: An improved production of (R)-[11C]PK11195 was achieved with reliable and reasonable radiochemical yield, high radiochemical purity and molecular activity. The cGMP compliant production allows the use of (R)-[11C]PK11195 for PET imaging in patients with inflammatory diseases.

The effectiveness of cell-based therapies to treat liver failure is often limited by the diseased liver environment. Here, we provide preclinical proof of concept for hepatocyte transplantation into lymph nodes as a cure for liver failure in a large-animal model with hereditary tyrosinemia type 1 (HT1), a metabolic liver disease caused by deficiency of fumarylacetoacetate hydrolase (FAH) enzyme. Autologous porcine hepatocytes were transduced ex vivo with a lentiviral vector carrying the pig Fah gene and transplanted into mesenteric lymph nodes. Hepatocytes showed early (6 h) and durable (8 months) engraftment in lymph nodes, with reproduction of vascular and hepatic microarchitecture. Subsequently, hepatocytes migrated to and repopulated the native diseased liver. The corrected cells generated sufficient liver mass to clinically ameliorate the acute liver failure and HT1 disease as early as 97 days post-transplantation. Integration site analysis defined the corrected hepatocytes in the liver as a subpopulation of hepatocytes from lymph nodes, indicating that the lymph nodes served as a source for healthy hepatocytes to repopulate a diseased liver. Therefore, ectopic transplantation of healthy hepatocytes cures this pig model of liver failure and presents a promising approach for the development of cures for liver disease in patients.