RESUMEN
Lorlatinib (PF-06463922) is a next-generation small-molecule inhibitor of the orphan receptor tyrosine kinase c-ros oncogene 1 (ROS1), which has a kinase domain that is physiologically related to anaplastic lymphoma kinase (ALK), and is undergoing Phase I/II clinical trial investigations for non-small cell lung cancers. An early goal is to measure the concentrations of this drug in brain tumour lesions of lung cancer patients, as penetration of the blood-brain barrier is important for optimal therapeutic outcomes. Here we prepare both 11C- and 18F-isotopologues of lorlatinib to determine the biodistribution and whole-body dosimetry assessments by positron emission tomography (PET). Non-traditional radiolabelling strategies are employed to enable an automated multistep 11C-labelling process and an iodonium ylide-based radiofluorination. Carbon-11-labelled lorlatinib is routinely prepared with good radiochemical yields and shows reasonable tumour uptake in rodents. PET imaging in non-human primates confirms that this radiotracer has high brain permeability.
Asunto(s)
Radioisótopos de Carbono/farmacocinética , Radioisótopos de Flúor/farmacología , Lactamas Macrocíclicas/química , Lactamas Macrocíclicas/farmacología , Tomografía de Emisión de Positrones/métodos , Aminopiridinas , Quinasa de Linfoma Anaplásico/antagonistas & inhibidores , Animales , Radioisótopos de Carbono/química , Técnicas de Química Sintética , Medios de Contraste/síntesis química , Medios de Contraste/farmacocinética , Radioisótopos de Flúor/química , Humanos , Marcaje Isotópico/métodos , Lactamas , Lactamas Macrocíclicas/farmacocinética , Macaca mulatta , Masculino , Ratones , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Pirazoles , Distribución Tisular , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Fluorine-18-labelled 6-(fluoro)-3-(1H-pyrrolo[2,3-c]pyridin-1-yl)isoquinolin-5-amine ([18 F]MK-6240) is a novel potent and selective positron emission tomography (PET) radiopharmaceutical for detecting human neurofibrillary tangles, which are made up of aggregated tau protein. Herein, we report the fully automated 2-step radiosynthesis of [18 F]MK-6240 using a commercially available radiosynthesis module, GE Healthcare TRACERlab FXFN . Nucleophilic fluorination of the 5-diBoc-6-nitro precursor with potassium cryptand [18 F]fluoride (K[18 F]/K222 ) was performed by conventional heating, followed by acid deprotection and semipreparative high-performance liquid chromatography under isocratic conditions. The isolated product was diluted with formulation solution and sterile filtered under Current Good Manufacturing Practices, and quality control procedures were established to validate this radiopharmaceutical for human use. At the end of synthesis, 6.3 to 9.3 GBq (170-250 mCi) of [18 F]MK-6240 was formulated and ready for injection, in an uncorrected radiochemical yield of 7.5% ± 1.9% (relative to starting [18 F]fluoride) with a specific activity of 222 ± 67 GBq/µmol (6.0 ± 1.8 Ci/µmol) at the end of synthesis (90 minutes; n = 3). [18 F]MK-6240 was successfully validated for human PET studies meeting all Food and Drug Administration and United States Pharmacopeia requirements for a PET radiopharmaceutical. The present method can be easily adopted for use with other radiofluorination modules for widespread clinical research use.
Asunto(s)
Radioisótopos de Flúor , Isoquinolinas/química , Ovillos Neurofibrilares/metabolismo , Tomografía de Emisión de Positrones/métodos , Radioquímica/métodos , Radiofármacos/química , Halogenación , Humanos , Isoquinolinas/síntesis química , Control de Calidad , Radiofármacos/síntesis químicaRESUMEN
In the interest of developing in vivo positron emission tomography (PET) probes for neuroimaging of calcium channels, we have prepared a carbon-11 isotopologue of a dihydropyridine Ca2+-channel antagonist, isradipine. Desmethyl isradipine (4-(benzo[c][1,2,5]oxadiazol-4-yl)-5-(isopropoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine -3-carboxylic acid) was reacted with [11C]CH3I in the presence of tetrabutylammonium hydroxide in DMF in an HPLC injector loop to produce the radiotracer in a good yield (6 ± 3% uncorrected radiochemical yield) and high specific activity (143 ± 90 GBq·µmol-1 at end-of-synthesis). PET imaging of normal rats revealed rapid brain uptake at baseline (0.37 ± 0.08% ID/cc (percent of injected dose per cubic centimeter) at peak, 15-60 s), which was followed by fast washout. After pretreatment with isradipine (2 mg·kg-1, i.p.), whole brain radioactivity uptake was diminished by 25%-40%. This preliminary study confirms that [11C]isradipine can be synthesized routinely for research studies and is brain penetrating. Further work on Ca2+-channel radiotracer development is planned.
Asunto(s)
Bloqueadores de los Canales de Calcio/farmacocinética , Hidrocarburos Yodados/química , Marcaje Isotópico/métodos , Isradipino/farmacocinética , Neuroimagen/métodos , Radiofármacos/farmacocinética , Animales , Encéfalo/metabolismo , Encéfalo/ultraestructura , Bloqueadores de los Canales de Calcio/química , Bloqueadores de los Canales de Calcio/metabolismo , Canales de Calcio/metabolismo , Radioisótopos de Carbono , Dimetilformamida/química , Evaluación Preclínica de Medicamentos , Semivida , Isradipino/química , Isradipino/metabolismo , Masculino , Permeabilidad , Tomografía de Emisión de Positrones , Compuestos de Amonio Cuaternario/química , Radiofármacos/química , Radiofármacos/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
UNLABELLED: Translation of new methodologies for labeling nonactivated aromatic molecules with (18)F remains a challenge. Here, we report a one-step, regioselective, metal-free (18)F-labeling method that uses a hypervalent iodonium(III) ylide precursor, to prepare the radiopharmaceutical (18)F-3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ((18)F-FPEB). METHODS: Automated radiosynthesis of (18)F-FPEB was achieved by reaction of the ylide precursor (4 mg) with (18)F-Et4NF in dimethylformamide at 80°C for 5 min and formulated for injection within 1 h. RESULTS: (18)F-FPEB was synthesized in 20% ± 5% (n = 3) uncorrected radiochemical yields relative to (18)F-fluoride, with specific activities of 666 ± 51.8 GBq (18 ± 1.4 Ci)/µmol at the end of synthesis and was validated for human use. CONCLUSION: Radiofluorination of iodonium (III) ylides proved to be an efficient radiosynthetic strategy for synthesis of (18)F-labeled radiopharmaceuticals.
Asunto(s)
Radioisótopos de Flúor/química , Yodo/química , Nitrilos/química , Compuestos Onio/química , Piridinas/química , Radiofármacos/síntesis química , Automatización , Electrones , Humanos , Hidrólisis , Oxígeno/química , Tomografía de Emisión de Positrones , Piridinas/síntesis química , Radioquímica , Radiofármacos/química , Temperatura , Factores de TiempoRESUMEN
Fluorine-18 labeled 7-(6-fluoropyridin-3-yl)-5H-pyrido[4,3-b]indole ([(18) F]T807) is a potent and selective agent for imaging paired helical filaments of tau and is among the most promising PET radiopharmaceuticals for this target in early clinical trials. The present study reports a simplified one-step method for the synthesis of [(18) F]T807 that is broadly applicable for routine clinical production using a GE TRACERlab™ FXFN radiosynthesis module. Key facets of our optimized radiosynthesis include development and use of a more soluble protected precursor, tert-butyl 7-(6-nitropyridin-3-yl)-5H-pyrido[4,3-b]indole-5-carboxylate, as well as new HPLC separation conditions that enable a facile one-step synthesis. During the nucleophilic fluorinating reaction with potassium cryptand [(18) F]fluoride (K[(18) F]/K222 ) in DMSO at 130 °C over 10 min the precursor is concurrently deprotected. Formulated [(18) F]T807 was prepared in an uncorrected radiochemical yield of 14 ± 3%, with a specific activity of 216 ± 60 GBq/µmol (5837 ± 1621 mCi/µmol) at the end of synthesis (60 min; n = 3) and validated for human use. This methodology offers the advantage of faster synthesis in fewer steps, with simpler automation that we anticipate will facilitate widespread clinical use of [(18) F]T807.
Asunto(s)
Carbolinas/síntesis química , Radioisótopos de Flúor/química , Marcaje Isotópico/métodos , Radiofármacos/síntesis química , Tomografía de Emisión de Positrones , Proteínas tau/metabolismoRESUMEN
2-[(Diphenylmethyl) sulfinyl]acetamide (modafinil), prescribed principally to treat narcolepsy, is undergoing assessment for other neuropsychiatric disorders and medical conditions. The neurochemical substrates of modafinil are unresolved. We postulated that modafinil enhances wakefulness by modulating dopamine (DAT), norepinephrine (NET), or serotonin (SERT) transporter activities. In vivo, we determined DAT and NET occupancy by modafinil by positron emission tomography imaging; in vitro, we determined modafinil activity at the DAT, NET, SERT, and rhesus monkey trace amine receptor 1 (TA1). In rhesus monkey, modafinil occupancy of striatal DAT was detected by [(11)C]2beta-carbomethoxy-3beta-4-(fluorophenyl)tropane and of thalamic NET by [(11)C](S,S)-2-(alpha-(2-methoxyphenoxy)-benzyl)morpholine. In vitro, modafinil effects in DAT-human embryonic kidney (HEK), NET-HEK, and SERT-HEK cells were investigated alone or combined with the TA1 receptor. Modafinil (i.v.) occupied striatal DAT sites (5 mg/kg: 35 +/- 12%, n = 4; 8 mg/kg: 54 +/- 3%, n = 3). In thalamus, modafinil occupied NET sites (5 mg/kg: 16 +/- 7.8%, n = 6; 8 mg/kg: 44 +/- 12%; n = 2). In vitro, modafinil inhibited [(3)H]dopamine (IC(50) = 6.4 microM), [(3)H]norepinephrine (IC(50) = 35.6 microM), and [(3)H]serotonin (IC(50) > 500 microM) transport via the human DAT, NET, and SERT. Modafinil did not activate the TA1 receptor in TA1-HEK cells, but it augmented a monoamine transporter-dependent enhancement of phenethylamine activation of TA1 in TA1-DAT and TA1-NET cells, but not in TA1-SERT cells. The present data provide compelling evidence that modafinil occupies the DAT and NET in living brain of rhesus monkeys and raise the possibility that modafinil affects wakefulness by interacting with catecholamine transporters in brain.
Asunto(s)
Compuestos de Bencidrilo/farmacología , Encéfalo/efectos de los fármacos , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/efectos de los fármacos , Proteínas de Transporte de Noradrenalina a través de la Membrana Plasmática/efectos de los fármacos , Receptores Acoplados a Proteínas G/efectos de los fármacos , Animales , Dopamina/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Relación Dosis-Respuesta a Droga , Femenino , Macaca mulatta , Masculino , Modafinilo , Norepinefrina/metabolismo , Proteínas de Transporte de Noradrenalina a través de la Membrana Plasmática/metabolismo , Fenetilaminas/farmacología , Tomografía de Emisión de Positrones , Proteínas de Transporte de Serotonina en la Membrana Plasmática/efectos de los fármacos , Vigilia/efectos de los fármacosRESUMEN
Viable dopamine neurons in Parkinson's disease express the dopamine transporter (DAT) and release dopamine (DA). We postulated that potent DAT inhibitors, with low affinity for the serotonin transporter (SERT), may elevate endogenously released extracellular dopamine levels to provide therapeutic benefit. The therapeutic potential of eight DAT inhibitors was investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated cynomolgus monkeys (Macaca fascicularis), with efficacy correlated with DAT occupancy as determined by positron emission tomography imaging in striatum. Four potent DAT inhibitors, with relatively high norepinephrine transporter, but low SERT affinities, that occupied the DAT improved activity in parkinsonian monkeys, whereas three high-affinity DAT inhibitors with low DAT occupancy did not. 2beta-Carbomethoxy-3alpha-(3,4-dichlorophenyl)-7beta-hydroxy-8-methyl-8-azabicyclo[3.2.1.]octane (O-1163) occupied the DAT but had short-lived pharmacological effects. The benztropine analog difluoropine increased general activity, improved posture, reduced body freeze, and produced sleep disturbances at high doses. (1R)-2beta-(1-Propanoyl)-3alpha-(4-fluorophenyl)tropane (O-1369) alleviated parkinsonian signs in advanced parkinsonian monkeys, by increasing general activity, improving posture, reducing body freeze, and sedation, but not significantly reducing bradykinesia or increasing locomotor activity. In comparison with the D(2)-D(3) DA receptor agonist quinelorane, O-1369 elicited oral/facial dyskinesias, whereas quinelorane did not improve posture or reduce balance and promoted stereotypy. In conclusion, DAT inhibitors with therapeutic potential combine high DAT affinity in vitro and high DAT occupancy of brain striatum in vivo with enduring day-time effects that do not extend into the nighttime. Advanced parkinsonian monkeys (80% DAT loss) respond more effectively to DAT inhibitors than mild parkinsonian monkeys (46% DAT loss). The therapeutic potential of dopamine transport inhibitors for Parkinson's disease warrants preclinical investigation.
Asunto(s)
Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/antagonistas & inhibidores , Trastornos Parkinsonianos/tratamiento farmacológico , Animales , Cocaína/análogos & derivados , Cocaína/metabolismo , Cocaína/farmacología , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Femenino , Macaca fascicularis , Masculino , Quinolinas/farmacología , Receptores de Dopamina D2/agonistas , Receptores de Dopamina D3/agonistasRESUMEN
This study assessed striatal dopamine 1 (D1) receptor binding in patients with major depressive disorder and anger attacks (MDD+A) and healthy volunteers. We used positron emission tomography with [(11)C]SCH 23,390 to compare 10 patients with MDD+A to 10 healthy volunteers. [(11)C]SCH 23,390 binding in bilateral striata was significantly lower in the MDD+A group when compared to healthy volunteers. These results implicate striatal D1 receptor dysfunction in MDD+A and further suggest an association between dopaminergic transmission and anger or aggression.
Asunto(s)
Ira/fisiología , Benzazepinas/farmacocinética , Cuerpo Estriado/diagnóstico por imagen , Tomografía de Emisión de Positrones , Receptores de Dopamina D1/metabolismo , Adulto , Agresión/fisiología , Radioisótopos de Carbono/farmacocinética , Trastorno Depresivo Mayor/diagnóstico por imagen , Dominancia Cerebral/fisiología , Dopamina/metabolismo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valores de ReferenciaRESUMEN
Although the cerebellum is increasingly being viewed as a brain area involved in cognition, it typically is excluded from circuitry considered to mediate stimulant-associated behaviors since it is low in dopamine. Yet, the primate cerebellar vermis (lobules II-III and VIII-IX) has been reported to contain axonal dopamine transporter immunoreactivity (DAT-IR). We hypothesized that DAT-IR-containing vermis areas would be activated in cocaine abusers by cocaine-related cues and, in healthy humans, would accumulate DAT-selective ligands. We used BOLD fMRI to determine whether cocaine-related cues activated DAT-IR-enriched vermis regions in cocaine abusers and positron emission tomography imaging of healthy humans to determine whether the DAT-selective ligand [11C]altropane accumulated in those vermis regions. Cocaine-related cues selectively induced BOLD activation in lobules II-III and VIII-IX in cocaine users, and, at early time points after ligand administration, we found appreciable [11C]altropane accumulation in lobules VIII-IX, possibly indicating DAT presence in this region. These data suggest that parts of cerebellar vermis mediate cocaine's persisting and acute effects. In light of prior findings illustrating vermis connections to midbrain dopamine cell body regions, established roles for the vermis as a locus of sensorimotor integration and motor planning, and findings of increased vermis activation in substance abusers during reward-related and other cognitive tasks, we propose that the vermis be considered one of the structures involved in cocaine- and other incentive-related behaviors.
Asunto(s)
Cerebelo/patología , Trastornos Relacionados con Cocaína/patología , Adulto , Anciano , Autorradiografía/métodos , Mapeo Encefálico , Isótopos de Carbono/farmacocinética , Cerebelo/irrigación sanguínea , Cerebelo/efectos de los fármacos , Cocaína/análogos & derivados , Cocaína/farmacocinética , Trastornos Relacionados con Cocaína/fisiopatología , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Técnicas In Vitro , Imagen por Resonancia Magnética/métodos , Masculino , Oxígeno/sangre , Tomografía de Emisión de Positrones , Cambios Post MortemRESUMEN
Stavudine, a potent antiviral agent for treating human immunodeficiency virus (HIV) infections, was radiolabeled with (11)C by methylation of a specifically designed precursor, 5'-O-(2-tetrahydropyranyl)-5-bromo-2',3'-didehydro-3'-deoxythymidine, with (11)C H(3)I. The radiolabeled drug was isolated by reverse phase HPLC. A total time of approximately 45 minutes was required for synthesis, purification and isolation of (11)C stavudine with chemical and radiochemical purities of greater than 98%. (11)C stavudine was combined with unlabeled drug (2.0 mg/kg) and used to study its pharmacokinetics in rats by measurement of radioactivity in excised tissues. In this species, there was rapid accumulation of drug in all tissue. In all tissues, with the exceptions of testis and brain, highest concentrations of drug were detected at 5 minutes after injection and decreased monotonically thereafter. The peak concentration (microg/g) of stavudine in blood was 1.78 +/- 0.16 and similar levels were achieved in most other tissues; heart 1.66 +/- 0.11, lung 1.60 +/- 0.15, liver 2.13 +/- 0.17, spleen 1.61 +/- 0.15, adrenal 1.47 +/- 0.20, stomach 1.40 +/- 0.11, GI tract 1.44 +/- 0.14, skeletal muscle 1.38 +/- 0.15 and bone 1.30 +/- 0.16. Much higher peak concentrations were achieved in kidney; 7.23 +/- 0.57 microg/g. Concentrations in testis were lower and remained relatively constant over 1 hour; peak 0.62 +/- 0.14 microg/g at 15 min Brain concentrations were low but increased monotonically over time; peak 0.26 +/- 0.02 microg/g at 60 min. Future PET studies with this radiopharmaceutical will allow in vivo measurements of the pharmacokinetics of stavudine in both animal models and human subjects.
Asunto(s)
Estavudina/farmacocinética , Animales , Radioisótopos de Carbono/química , Radioisótopos de Carbono/farmacocinética , Marcaje Isotópico/métodos , Masculino , Tasa de Depuración Metabólica , Especificidad de Órganos , Radiofármacos/síntesis química , Radiofármacos/farmacocinética , Ratas , Ratas Sprague-Dawley , Estavudina/síntesis química , Distribución TisularRESUMEN
Without exception, therapeutic and addictive drugs that produce their primary effects by blocking monoamine transporters in brain contain an amine nitrogen in their structure. This fundamental canon of drug design was based on a prevailing premise that an amine nitrogen is required to mimic the structures of monoamine neurotransmitters and other natural products. Non-amines, a novel class of compounds that contain no amine nitrogen, block monoamine transporters in the nM range and display markedly high selectivity for monoamine transporters, but not for receptors. Non-amines retain the spectrum of biochemical and pharmacological properties characteristic of amine-bearing counterparts. These novel drugs compel a revision of current concepts of drug-monoamine transporter complex formation and open avenues for discovery of a new generation of therapeutic drugs.
Asunto(s)
Inhibidores de Captación de Dopamina/metabolismo , Glicoproteínas de Membrana , Moduladores del Transporte de Membrana , Proteínas de Transporte de Membrana/antagonistas & inhibidores , Proteínas de Transporte de Membrana/metabolismo , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Proteínas del Tejido Nervioso/metabolismo , Animales , Aminas Biogénicas/metabolismo , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Inhibidores de Captación de Dopamina/farmacología , Relación Dosis-Respuesta a Droga , Macaca mulatta , Masculino , Ratas , Ratas Wistar , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/fisiología , Saimiri , Relación Estructura-ActividadRESUMEN
The dopamine transporter (DAT), located presynaptically on dopamine neurons, provides a marker for Parkinson's disease (Pd) and attention deficit hyperactivity disorder (ADHD). In ADHD, DAT density levels are elevated, while in Pd these levels are depleted. The depletion of DAT levels also corresponds with the loss of dopamine. We now describe the design, synthesis, biology, and SPECT imaging in nonhuman primates of second-generation (99m)technetium-based tropane ligands that bind potently and selectively to the DAT. We demonstrate that improved selectivity and biological stability allows sufficient agent to enter the brain and label the DAT in vivo to provide a quantitative measure of DAT density in nonhuman primates. We introduce FLUORATEC (N-[(2-((3'-N'-propyl-(1"R)-3"alpha-(4-fluorophenyl)tropane-2"beta-1-propanoyl)(2-mercaptoethyl)amino)acetyl)-2-aminoethanethiolato]technetium(V) oxide), a DAT imaging agent that has emerged from these studies and is now in phase 1 clinical trials in the U.S.