Background: Onfasprodil (MIJ821) is a highly potent and novel selective NR2B subunit negative allosteric modulator. This phase 2, randomized, placebo-controlled, proof-of-concept study evaluated efficacy and safety of onfasprodil in patients with treatment-resistant major depression (TRD). Methods: Adults with TRD who did not respond to ≥2 antidepressants were randomized (3:3:3:3:6:4) to receive a 40-minute intravenous infusion of onfasprodil 0.16 mg/kg weekly (n = 11), onfasprodil 0.16 mg/kg biweekly (n = 10), onfasprodil 0.32 mg/kg weekly (n = 10), onfasprodil 0.32 mg/kg biweekly (n = 9), placebo weekly (n=20), or ketamine 0.5 mg/kg weekly (n= 10) for 6 weeks. Primary end point was change from baseline in Montgomery-Asberg Depression Rating Scale (MADRS) score at 24 hours. Secondary end points were change in MADRS score at 48 hours and at final follow-up at 6 weeks. Safety and tolerability were assessed during the study. Results: Of 70 randomized patients, 53 (75.7%) completed the study. At 24 hours, adjusted mean differences versus placebo for pooled onfasprodil 0.16 mg/kg, 0.32 mg/kg, and ketamine groups were -8.25 (P = .001), -5.71 (P = .019), and -5.67 (P = .046), and at 48 hours, -7.06 (P = .013), -7.37 (P = .013), and -11.02 (P = .019), respectively. At Week 6, adjusted arithmetic mean MADRS difference between ketamine and placebo was -5.24 (80% CI, -10.42 to -0.06; P= .0974). At Week 6, the difference versus placebo on MADRS was -5.78 (P= .0427) for pooled 0.16 mg/kg and -4.24 (P= .1133) for pooled 0.32 mg/kg groups. The commonest treatment-emergent adverse events in the onfasprodil groups were dizziness (14.3%), transient amnesia (14.3%), and somnolence (11.4%). It had overall a good safety profile and was well tolerated. Conclusion: Onfasprodil appeared to be effective and well-tolerated across all dosing regimens in patients with TRD and demonstrated rapid onset of action (24 hours) with evidence of antidepressant effects to be maintained at Week 6, particularly for the lower-dose group. Trial Registration: ClinicalTrials.gov identifier: NCT03756129.

Abstract This single‐center study administered MIJ821 (onfasprodil) as an intravenous infusion to healthy volunteers and included two parts: a single ascending dose study (Part 1) and a repeated intravenous dose study (Part 2). Primary objective was to evaluate the safety and tolerability of single ascending intravenous doses infused over a 40‐min period and of two repeated doses (1 week apart) of MIJ821 in healthy volunteers. Secondary objectives were to assess the pharmacokinetics of MIJ821 after intravenous infusion in Part 1 and Part 2 of the study. Overall, 43 subjects in Part 1 and 12 subjects in Part 2 were randomized in the study. Median age in Part 1 and Part 2 was 45.0 and 43.5 years, respectively, with the majority being Caucasian (Part 1: 84%; Part 2: 92%). 19 subjects (44.2%) in Part 1 and 8 subjects (66.7%) in Part 2 experienced at least one adverse event (AE). Following single dose in Part 1 and Part 2, the AUCinf values of MIJ821 increased in a dose‐proportional manner across the dose range 0.016–0.48 mg/kg and the Cmax values in a slight overproportional manner across the dose range 0.048–0.48 mg/kg. At the highest dose of 0.48 mg/kg, the geometric mean AUCinf was 708 h ng/mL and the geometric mean Cmax was 462 ng/mL. Inspection of 1‐h post‐dose resting electroencephalography activity across cohorts showed a relationship to administered dose, providing exploratory evidence of distal target engagement. In conclusion, MIJ821 showed a good safety and tolerability profile in healthy volunteers. Dissociative AEs were mild, transient, and dose‐dependent.

Huntington’s Disease (HD) is a progressive neurodegenerative disorder caused by CAG trinucleotide repeat expansions in exon 1 of the huntingtin ( HTT ) gene. The mutant HTT (mHTT) protein causes neuronal dysfunction, causing progressive motor, cognitive and behavioral abnormalities. Current treatments for HD only alleviate symptoms, but cerebral spinal fluid (CSF) or central nervous system (CNS) delivery of antisense oligonucleotides (ASOs) or virus vectors expressing RNA-induced silencing (RNAi) moieties designed to induce mHTT mRNA lowering have progressed to clinical trials. Here, we present an alternative disease modifying therapy the orally available, brain penetrant small molecule branaplam. By promoting inclusion of a pseudoexon in the primary transcript, branaplam lowers mHTT protein levels in HD patient cells, in an HD mouse model and in blood samples from Spinal Muscular Atrophy (SMA) Type I patients dosed orally for SMA (NCT02268552). Our work paves the way for evaluating branaplam’s utility as an HD therapy, leveraging small molecule splicing modulators to reduce expression of dominant disease genes by driving pseudoexon inclusion.

1. AFQ056 phenotyping results indicate that CYP1A1 is responsible for the formation of the oxidative metabolite, M3. In line with the predominant assumption that CYP1A1 is mainly expressed in extrahepatic tissues, only traces of M3 were detected in hepatic systems. The aim of this study was to investigate the pulmonary CYP1A1 mediated metabolism of AFQ056 in rat. 2. Western blot analysis confirmed that CYP1A1 is expressed in rat lung albeit at low levels. M3 formation was clearly observed in recombinant rat CYP1A1, lung microsomes and lung tissue slices and was strongly inhibited by ketoconazole in the incubations. As CYP3A4 and CYP2C9 metabolites were only observed at trace levels, we concluded that the reduced M3 formation was due to CYP1A1 inhibition. 3. AFQ056 lung clearance (CLlung) as estimated from in vitro data was predicted to be negligible (<1% pulmonary blood flow). This was confirmed by in vivo experiments where intravenous and intra-arterial dosing to rats failed to show significant pulmonary extraction. 4. While rat lung may make a contribution to the formation of M3, it is unlikely to be the only organ involved in this process and further experiments are required to investigate the potential metabolic elimination routes for AFQ056.

The chemical modification 2′‐O‐methyl of nucleosides is often used to increase siRNA stability towards nuclease activities. However, the metabolic fate of modified nucleosides remains unclear. Therefore, the aim of this study was to determine the mass balance, pharmacokinetic, and absorption, distribution, metabolism, and excretion (ADME)‐properties of tritium‐labeled 2′‐O‐methyluridine, following a single intravenous dose to male CD‐1 mice. The single intravenous administration of [5‐3H]‐2′‐O‐methyluridine was well tolerated in mice. Radioactivity was rapidly and widely distributed throughout the body and remained detectable in all tissues investigated throughout the observation period of 48 h. After an initial rapid decline, blood concentrations of total radiolabeled components declined at a much slower rate. [3H]‐2′‐O‐Methyluridine represented a minor component of the radioactivity in plasma (5.89% of [3H]‐AUC0‐48 h). Three [3H]‐2′‐O‐methyluridine metabolites namely uridine (M1), cytidine (M2), and uracil (M3) were the major circulating components representing 32.8%, 8.11%, and 23.6% of radioactivity area under the curve, respectively. The highest concentrations of total radiolabeled components and exposures were observed in kidney, spleen, pineal body, and lymph nodes. The mass balance, which is the sum of external recovery of radioactivity in excreta and remaining radioactivity in carcass and cage wash, was complete. Renal excretion accounted for about 52.7% of the dose with direct renal excretion of the parent in combination with metabolism to the endogenous compounds cytidine, uracil, cytosine, and cytidine.

Absorption, distribution, metabolism, and excretion properties of a small interfering RNA (siRNA) formulated in a lipid nanoparticle (LNP) vehicle were determined in male CD-1 mice following a single intravenous administration of LNP-formulated [(3)H]-SSB siRNA, at a target dose of 2.5 mg/kg. Tissue distribution of the [(3)H]-SSB siRNA was determined using quantitative whole-body autoradiography, and the biostability was determined by both liquid chromatography mass spectrometry (LC-MS) with radiodetection and reverse-transcriptase polymerase chain reaction techniques. Furthermore, the pharmacokinetics and distribution of the cationic lipid (one of the main excipients of the LNP vehicle) were investigated by LC-MS and matrix-assisted laser desorption ionization mass spectrometry imaging techniques, respectively. Following i.v. administration of [(3)H]-SSB siRNA in the LNP vehicle, the concentration of parent guide strand could be determined up to 168 hours p.d. (post dose), which was ascribed to the use of the vehicle. This was significantly longer than what was observed after i.v. administration of the unformulated [(3)H]-SSB siRNA, where no intact parent guide strand could be observed 5 minutes post dosing. The disposition of the siRNA was determined by the pharmacokinetics of the formulated LNP vehicle itself. In this study, the radioactivity was widely distributed throughout the body, and the total radioactivity concentration was determined in selected tissues. The highest concentrations of radioactivity were found in the spleen, liver, esophagus, stomach, adrenal, and seminal vesicle wall. In conclusion, the LNP vehicle was found to drive the kinetics and biodistribution of the SSB siRNA. The renal clearance was significantly reduced and its exposure in plasma significantly increased compared with the unformulated [(3)H]-SSB siRNA.

Absorption, distribution, metabolism, and excretion (ADME) properties of a siRNA formulated in a liposome nanoparticle (LNP) vehicle were determined in male CD-1 mice following a single intravenous administration of LNP-formulated [ 3 H]-SSB siRNA, at a target dose level of 2.5 mg/kg. Tissue distribution of the [ 3 H]-siRNA was determined using quantitative whole-body autoradiography (QWBA) and the biostability was determined by both LC-MS with radiodetection and RT-qPCR techniques. Furthermore, the pharmacokinetics and distribution of the cationic lipid (one of the main excipients of the LNP-vehicle), was investigated by LC-MS and MALDI-MS imaging techniques, respectively. Following i.v. administration of [ 3 H]-SSB siRNA in the LNP-vehicle, the concentration of parent guide strand could be determined up to 168 h p.d. , which was ascribed to the use of the vehicle. This was significantly longer than what was observed after i.v. administration of the unformulated [ 3 H]-SSB siRNA, where no intact parent guide strand could be observed 5 minutes post dosing. The disposition of the siRNA was determined by the pharmacokinetics of the formulated LNP-vehicle itself. In this study, the radioactivity was widely distributed throughout the body, and the total radioactivity concentration was determined in selected tissues. The highest concentrations of radioactivity were found in spleen, liver, esophagus, stomach, adrenal and seminal vesicle wall. In conclusion, the LNP-vehicle was found to drive the kinetics and biodistribution of the SSB siRNA. The renal clearance was significantly reduced and its exposure in plasma significantly increased compared to the unformulated [ 3 H]-SSB siRNA.

Absorption, distribution, metabolism, and excretion properties of two unformulated model short interfering RNA (siRNAs) were determined using a single internal [(3)H]-radiolabeling procedure, in which the full-length oligonucleotides were radiolabeled by Br/(3)H -exchange. Tissue distribution, excretion, and mass balance of radioactivity were investigated in male CD-1 mice after a single intravenous administration of the [(3)H]siRNAs, at a target dose level of 5 mg/kg. Quantitative whole-body autoradiography and liquid scintillation counting techniques were used to determine tissue distribution. Radiochromatogram profiles were determined in plasma, tissue extracts, and urine. Metabolites were separated by liquid chromatography and identified by radiodetection and high-resolution accurate mass spectrometry. In general, there was little difference in the distribution of total radiolabeled components after administration of the two unformulated [(3)H]siRNAs. The radioactivity was rapidly and widely distributed throughout the body and remained detectable in all tissues investigated at later time points (24 and 48 hours for [(3)H]MRP4 (multidrug resistance protein isoform 4) and [(3)H]SSB (Sjögren Syndrome antigen B) siRNA, respectively). After an initial rapid decrease, concentrations of total radiolabeled components in dried blood decreased at a much slower rate. A nearly complete mass balance was obtained for the [(3)H]SSB siRNA, and renal excretion was the main route of elimination (38%). The metabolism of the two model siRNAs was rapid and extensive. Five minutes after administration, no parent compound could be detected in plasma. Instead, radiolabeled nucleosides resulting from nuclease hydrolysis were observed. In the metabolism profiles obtained from various tissues, only radiolabeled nucleosides were found, suggesting that siRNAs are rapidly metabolized and that the distribution pattern of total radiolabeled components can be ascribed to small molecular weight metabolites.

OBJECTIVE: To determine which sphingosine 1-phosphate (S1P) receptor subtype is primarily targeted by S1P and fingolimod in the brain in vivo, and to monitor a potential drug-dependent down-regulation of receptors in the brain. BACKGROUND: Increased levels of S1P in the cerebrospinal fluid of patients with multiple sclerosis (MS) are directly proportional to expanded disability status scale (EDSS) score. Further, S1P receptor expression is up-regulated in many inflammatory conditions, including the MS brain. These data suggest a critical role of pro-inflammarory S1P-S1P receptor signaling in MS. DESIGN/METHODS: Brain homogenates/membranes were prepared from untreated and fingolimod-treated rats (0.3 mg/kg/day) by centrifugation. S1P receptor expression and down-modulation of receptor protein was determined using western blots, ³³P-S1P binding assays and receptor subtype-specific compounds. Brain penetration of fingolimod was confirmed by autoradiography and HPLC. RESULTS: Fingolimod and its active metabolite, fingolimod-P, were detectable in brain and spinal cord, reaching high nM levels. ³³P-S1P effectively bound to brain tissue from untreated but not from fingolimod-treated animals. Binding of ³³P-S1P was completely blunted by unlabeled S1P1-specific antagonists (NIBR-0213), indicating a major involvement of S1P1 in S1P-binding. Accordingly, high levels of S1P1 receptor protein were detectable in the brain of untreated animals, but levels were reduced by >70% in fingolimod-treated rats. After drug withdrawal, brain S1P1 levels recovered to normal within 5 weeks. CONCLUSIONS: The data show that in the brain, S1P1 is the dominant S1P receptor subtype that binds pro-inflammatory S1P. Fingolimod treatment down-modulates S1P1 in a reversible manner, and therefore may reduce excessive S1P-S1P1-signaling, possibly breaking the pro-inflammatory cascade through a direct action on neural cells. This mechanism may contribute to the anti-inflammatory effect of fingolimod in the brain of patients with MS, demonstrated by the significant decrease in the number of inflammatory markers on brain magnetic resonance imaging in recent clinical trials. Supported by: Novartis Pharma AG, Basel. Disclosure: Dr. Brinkmann has received personal compensation for activities with Novartis as an employee. Dr. Brinkmann has received research support from Novartis. Dr. Streiff has received personal compensation for activities with Novartis as an employee. Dr. Streiff has received research support from Novartis. Dr. Kaupmann has received personal compensation for activities with Novartis as an employee. Dr. Kaupmann has receied research support from Novartis. Dr. Billich has received personal compensation for activities with Novartis. Dr. Billich has received research support from Novartis. Dr. Faller has received personal compensation for activities with Novartis as an employee. Dr. Faller has received research support from Novartis. Dr. Bollbuck has received personal compensation for activities with Novartis as an employee. Dr.Bollbuck has received resarch support from Novartis. Dr. Bigaud has received personal compensation for activities with Novartis. Dr. Bigaud has received research support from Novartis. Dr. Quancard has received personal compensation for activities with Novartis. Dr. Quancard has received research support from Novartis. Dr. Kinzel has received personal compensation for activities with Novartis as an employee. Dr. Kinzel has received research support from Novartis.

Efficient tissue-specific delivery is a crucial factor in the successful development of therapeutic oligonucleotides. Screening for novel delivery methods with unique tissue-homing properties requires a rapid, sensitive, flexible and unbiased technique able to visualize the in vivo biodistribution of these oligonucleotides. Here, we present whole body scanning PCR, a platform that relies on the local extraction of tissues from a mouse whole body section followed by the conversion of target-specific qPCR signals into an image. This platform was designed to be compatible with a novel RT-qPCR assay for the detection of siRNAs and with an assay suitable for the detection of heavily chemically modified oligonucleotides, which we termed Chemical-Ligation qPCR (CL-qPCR). In addition to this, the platform can also be used to investigate the global expression of endogenous mRNAs and non-coding RNAs. Incorporation of other detection systems, such as aptamers, could even further expand the use of this technology.

Deferasirox (Exjade, ICL670, CGP72670) is an iron-chelating drug for p.o. treatment of transfusional iron overload in patients with β-thalassemia or sickle cell disease. The pharmacokinetics and disposition of deferasirox were investigated in rats. The animals received single intravenous (10 mg/kg) or p.o. (10 or 100 mg/kg) doses of 14C-radiolabeled deferasirox. Biological samples were analyzed for radioactivity (liquid scintillation counting, quantitative whole-body autoradioluminography), for deferasirox and its iron complex [high-performance liquid chromatography (HPLC)/UV], and for metabolites (HPLC with radiodetection, liquid chromatography/mass spectrometry, 1H and 13C NMR, and two-dimensional NMR techniques). At least 75% of p.o.-dosed deferasirox was absorbed. The p.o. bioavailability was 26% at the 10 mg/kg dose and showed an overproportional increase at the 100 mg/kg dose, probably because of saturation of elimination processes. Deferasirox-related radioactivity was distributed mainly to blood, excretory organs, and gastrointestinal tract. Enterohepatic recirculation of deferasirox was observed. No retention occurred in any tissue. The placental barrier was passed to a low extent. Approximately 3% of the dose was transferred into the breast milk. Excretion of deferasirox and metabolites was rapid and complete within 7 days. Key clearance processes were hepatic metabolism and biliary elimination via multidrug resistance protein 2. Deferasirox, iron complex, and metabolites were excreted largely via bile and feces (total ≥90%). Metabolism included glucuronidation at the carboxylate group (acyl glucuronide M3) and at phenolic hydroxy groups, as well as, to a lower degree, cytochrome P450-catalyzed hydroxylations. Two hydroxylated metabolites (M1 and M2) were administered to rats and were shown not to contribute substantially to iron elimination in vivo.