Search

Aims: Phosphodiesterase 2 (PDE2) regulates intracellular cyclic adenosine monophosphate and guanosine monophosphate (cAMP/cGMP) levels, which contribute to processes crucial for learning and memory. BI 474121, a potent and selective PDE2 inhibitor, is in development for treating cognitive impairment associated with schizophrenia. Methods: The effects of BI 474121 on cGMP concentrations were first assessed in rat cerebrospinal fluid (CSF) to demonstrate central nervous system (CNS) and functional target engagement. Next, a Phase I study in healthy participants assessed the pharmacokinetics of BI 474121 in CSF vs. plasma, the pharmacodynamics of BI 474121 by measuring cGMP concentrations in the CSF, and the safety of BI 474121. Results: In rats, BI 474121 was associated with a dose‐dependent increase (71% at the highest dose tested [3.0 mg kg−1]) in cGMP levels in the CSF relative to vehicle (P < 0.001). In healthy participants, the maximum‐measured concentration CSF‐to‐plasma ratio for BI 474121 exposure was similar following single oral doses of BI 474121 2.5, 10, 20 and 40 mg (dose‐adjusted geometric mean: 8.96% overall). BI 474121 2.5–40 mg administration in healthy participants also increased cGMP levels in CSF (maximum exposure‐related change from baseline ratio, BI 474121: 1.44–2.20 vs. placebo: 1.26). The most common treatment‐emergent adverse event (AE) was mild‐to‐moderate post‐lumbar puncture syndrome, which resolved with standard treatment. No AEs of special interest were observed. Conclusions: BI 474121 crosses the blood–brain barrier to inhibit PDE2, supporting cGMP as a translational marker to monitor CNS target engagement. These findings promote further clinical development of BI 474121. ClinicalTrials.gov number (NCT04672954). [ABSTRACT FROM AUTHOR]

Introduction/Aims: Corneal confocal microscopy (CCM) detects small nerve fiber loss and correlates with skin biopsy findings in diabetic neuropathy. In chronic idiopathic axonal polyneuropathy (CIAP) this correlation is unknown. Therefore, we compared CCM and skin biopsy in patients with CIAP to healthy controls, patients with painful diabetic neuropathy (PDN) and diabetics without overt neuropathy (DM). Methods: Participants with CIAP and suspected small fiber neuropathy (n = 15), PDN (n = 16), DM (n = 15), and healthy controls (n = 16) underwent skin biopsy and CCM testing. Inter‐center intraclass correlation coefficients (ICC) were calculated for CCM parameters. Results: Compared with healthy controls, patients with CIAP and PDN had significantly fewer nerve fibers in the skin (IENFD: 5.7 ± 2.3, 3.0 ± 1.8, 3.9 ± 1.5 fibers/mm, all p <.05). Corneal nerve parameters in CIAP (fiber density 23.8 ± 4.9 no./mm2, branch density 16.0 ± 8.8 no./mm2, fiber length 13.1 ± 2.6 mm/mm2) were not different from healthy controls (24.0 ± 6.8 no./mm2, 22.1 ± 9.7 no./mm2, 13.5 ± 3.5 mm/mm2, all p >.05). In patients with PDN, corneal nerve fiber density (17.8 ± 5.7 no./mm2) and fiber length (10.5 ± 2.7 mm/mm2) were reduced compared with healthy controls (p <.05). CCM results did not correlate with IENFD in CIAP patients. Inter‐center ICC was 0.77 for fiber density and 0.87 for fiber length. Discussion: In contrast to patients with PDN, corneal nerve parameters were not decreased in patients with CIAP and small nerve fiber damage. Therefore, CCM is not a good biomarker for small nerve fiber loss in CIAP patients. [ABSTRACT FROM AUTHOR]

Dermal allyl isothiocyanate (AITC) administration and whole-body heat stress (WBHS) are two challenge models that are used to evaluate physiological mechanisms of vasodilation and pharmacological activity in humans. Their exact vasodilatory mechanisms in humans are not fully elucidated but are likely to be nitric oxide (NO)-mediated. This study aimed to evaluate whether there is overlap in the vasodilatory pathways of dermal AITC application and WBHS by combining the challenges. In this open-label interventional study, healthy volunteers underwent dermal administration of AITC twice: under basal conditions and during WBHS. Dermal blood flow (DBF) was non-invasively measured using laser speckle contrast imaging four times, once in each of the following situations: baseline, WBHS only, AITC only, and WBHS combined with AITC. A total of 12 male volunteers, aged 18– 61 years, participated in the study. Compared to baseline, following AITC application, their DBF increased by 63.43 AU (baseline: 32.55, 95% CI [17.78, 47.31] AU, AITC only: 95.97, 95% CI [81.21, 110.7] AU, p < 0.0001). During WBHS, the increase in DBF after AITC was 42.76 AU (WBHS only: 87.25, 95% CI [72.49, 102.0] AU, WBHS+AITC: 130.0, 95% CI [115.2, 144.8] AU, p < 0.0001). The combination of WBHS and AITC resulted in a lower DBF than the sum of the DBF responses to AITC and WBHS when applied separately (ED 20.67, 95% CI [− 3.532, 44.88], p = 0.0916). This might point towards the presence of an interaction in the vasodilatory mechanism of AITC application and WBHS, possibly indicating overlap in their NOS-driven vasodilatory pathways. [ABSTRACT FROM AUTHOR]

C–C Motif Chemokine Ligand 17 (CCL17) is a chemokine that binds and signals through the G‐protein coupled CC‐chemokine receptor 4 and has been implicated in the development of inflammatory and arthritic pain. GSK3858279 is a high‐affinity, first‐in‐class, monoclonal antibody, binding specifically to CCL17 and inhibiting downstream signaling. In this phase I, randomized, single‐center, double‐blind, placebo‐controlled, three‐period, incomplete‐block crossover study (NCT04114656), the analgesic effects and safety of intravenous GSK3858279 were assessed in a battery of evoked acute pain assessments on healthy, adult (aged ≥18 years), male participants. Participants were randomized 1:1 to receive either one placebo (0.9% w/v NaCl) dose followed by two GSK3858279 doses (PAA treatment sequence), or one GSK3858279 dose followed by two placebo doses (APP treatment sequence). The co‐primary end points were ultraviolet B heat pain detection threshold (°C), cold pressor time to pain tolerance threshold (PTT, sec), and electrical PTT (mA, single stimulus). Twenty‐one participants were enrolled (PAA = 11; APP = 10). Mean age (standard deviation) was 29.3 (7.9) years for PAA, 31.1 (7.7) years for APP. No significant differences were observed in the analgesic effect between GSK3858279 and placebo for any end point. Exposure to GSK3858279 was similar between Period 1 (APP sequence), and Periods 2 and 3 (PAA sequence), with some GSK3858279 carry‐over. Changes in serum CCL17 levels were consistent with the expected GSK3858279 activity. All drug‐related adverse events were mild in intensity and caused no discontinuations. The absence of an efficacy signal in this acute pain model does not preclude efficacy in chronic pain states. [ABSTRACT FROM AUTHOR]

Background: Noradrenergic signaling declines in Parkinson's disease (PD) following locus coeruleus neurodegeneration. Epidemiologic studies demonstrate that β-acting drugs slow PD progression. Objective: The primary objective was to compare the safety and effects of 3 β-adrenoceptor (β-AR) acting drugs on central nervous system (CNS) function after a single dose in healthy volunteers (HVs) and evaluate the effects of multiple doses of β-AR acting drugs in HVs and PD-patients. Methods: In Part A, HVs received single doses of 32 mg salbutamol, 160μg clenbuterol, 60 mg pindolol and placebo administered in a randomized, 4-way cross-over study. In Part B (randomized cross-over) and Part C (parallel, 2:1 randomized), placebo and/or clenbuterol (20μg on Day 1, 40μg on Day 2, 80μg on Days 3–7) were administered. CNS functions were assessed using the NeuroCart test battery, including pupillometry, adaptive tracking and recall tests. Results: Twenty-seven HVs and 12 PD-patients completed the study. Clenbuterol improved and pindolol reduced the adaptive tracking and immediate verbal recall performance. Clenbuterol and salbutamol increased and pindolol decreased pupil-to-iris ratios. Clenbuterol was selected for Parts B and C. In Part B, clenbuterol significantly increased performance in adaptive tracking with a tendency toward improved performance in immediate and delayed verbal recall. In Part C trends toward improved performance in immediate and delayed verbal recall were observed in PD-patients. Typical cardiovascular peripheral β2-AR effects were observed with clenbuterol. Conclusions: This study demonstrates the pro-cognitive effects of clenbuterol in HVs with similar trends in PD-patients. The mechanism of action is likely activation of β2-ARs in the CNS. Plain Language Summary: Aims and Purpose of the Research: This research aimed to explore how three different drugs affect brain function. These drugs are salbutamol, clenbuterol, and pindolol and work in the brain by stimulating specific brain cells that can improve aspects like memory and coordination. The main question was to see how safe these drugs were and how they impact the brain function after one dose in healthy people, and after multiple doses in both healthy people and those with Parkinson's disease. Background of the Research: Parkinson's disease is a condition where brain cells start to die, which affects different areas of the brain, including movement function, as well as memory and attention. This research matters because finding drugs that affect the brain function could improve the lives of people with Parkinson's disease. Methods and Research Design: The study was conducted in three parts. In the first part, healthy volunteers took one dose of each of the three drugs— salbutamol, clenbuterol, and pindolol— as well as a placebo (a harmless pill that has no effect). The researchers tested the participants' brain functions using various tasks including memory tests and eye response measurements. In the second and third part, healthy people and people with Parkinson's disease took the drug that performed best in healthy volunteers for seven days. Results and Importance: In the first part, a single dose of clenbuterol was safe and improved memory and attentions tasks in healthy people, and therefore was chosen for further testing in the second and third part. In these parts, multiple doses of clenbuterol were safe and helped improve memory and attention tasks in healthy people, with similar positive trends seen in people with Parkinson's disease. The study suggests that clenbuterol might help improve brain function by activating specific receptors in the brain. These results are important because they suggest that clenbuterol could be a potential treatment to help improve brain function in people with Parkinson's disease. However, more research is needed to fully understand its effects and to confirm these findings. [ABSTRACT FROM AUTHOR]

Dynamic balance assessments such as walking adaptability may yield a more realistic prediction of drug‐induced falls compared with postural stability measurements, as falls often result from limited gait adjustments when walking. The Interactive Walkway (IWW) measures walking adaptability but sensitivity to medication effects is unknown. If proven sensitive and specific, IWW could serve as a biomarker for targeted fall‐risk assessments in early clinical drug development. In this three‐way crossover study, 18 healthy elderly (age: 65–80 years) subjects received 5 mg zolpidem, 10 mg suvorexant, or placebo in the morning. Assessments were performed pre‐dose and approximately hourly until 9 h post‐dose. IWW assessments included an 8‐meter walking test, goal‐directed stepping, obstacle‐avoidance, and tandem‐walking. Other pharmacodynamic measurements were the Timed‐Up‐and‐Go (TUG) test at a comfortable and fast pace, adaptive tracking, and body sway. A decline in performance was observed for zolpidem compared with placebo for 3 h post‐dose in IWW walking adaptability outcome measures, TUG, adaptive tracking, and body sway. For the IWW tasks, a decrease in walking speed (among others) was observed. IWW parameters were not affected by suvorexant compared with placebo at any timepoint. However, an increase of 9.8% (95%CI: 1.8%, 18.5%) in body sway was observed for suvorexant compared with placebo up to 3 h post‐dose. The IWW successfully quantified drug effects of two hypnotic drugs and distinguished between zolpidem and suvorexant regarding their effects on walking. As a biomarker, the IWW demonstrated sensitivity in assessing dynamic balance and potential fall risk in early phase clinical drug development. [ABSTRACT FROM AUTHOR]

Aims: Dysfunction of nitric oxide‐soluble guanylate cyclase (sGC)–cyclic guanosine monophosphate signalling is implicated in the pathophysiology of cognitive impairment. Zagociguat is a central nervous system (CNS) penetrant sGC stimulator designed to amplify nitric oxide–cyclic guanosine monophosphate signalling in the CNS. This article describes a phase 1b study evaluating the safety and pharmacodynamic effects of zagociguat. Methods: In this randomized crossover study, 24 healthy participants aged ≥65 years were planned to receive 15 mg zagociguat or placebo once daily for 2 15‐day periods separated by a 27‐day washout. Adverse events, vital signs, electrocardiograms and laboratory tests were conducted to assess safety. Pharmacokinetics of zagociguat were evaluated in blood and cerebrospinal fluid (CSF). Pharmacodynamic assessments included evaluation of cerebral blood flow, CNS tests, pharmaco‐electroencephalography, passive leg movement and biomarkers in blood, CSF and brain. Results: Twenty‐four participants were enrolled; 12 participants completed both treatment periods, while the other 12 participants completed only 1 treatment period. Zagociguat was well‐tolerated and penetrated the blood–brain barrier, with a CSF/free plasma concentration ratio of 0.45 (standard deviation 0.092) measured 5 h after the last dose of zagociguat on Day 15. Zagociguat induced modest decreases in blood pressure. No consistent effects of zagociguat on other pharmacodynamic parameters were detected. Conclusion: Zagociguat was well‐tolerated and induced modest blood pressure reductions consistent with other sGC stimulators. No clear pharmacodynamic effects of zagociguat were detected. Studies in participants with proven reduced cerebral blood flow or CNS function may be an avenue for further evaluation of the compound. [ABSTRACT FROM AUTHOR]