Oral treatment with the all-d-peptide RD2 enhances cognition in aged beagle dogs - A model of sporadic Alzheimer's disease

Oral PRI-002 treatment in patients with MCI or mild AD: a randomized, double-blind phase 1b trial

Self-replicating amyloid beta (Aβ) oligomers are considered as one of the major drivers for disrupted synaptic function and plasticity, leading to impaired neuronal viability and progression of Alzheimer's disease (AD). Here, we investigated the safety, tolerability and pharmacokinetics of the anti-oligomeric peptide PRI-002, which was developed to disassemble toxic Aβ oligomers into non-toxic monomers. In a randomized, double-blind, single-center phase 1b trial, 20 patients aged between 50 and 80 years, with mild neurocognitive impairment (MCI) or mild dementia due to AD were recruited. Eligible patients were randomly assigned (1:1) to receive 300 mg PRI-002 once daily (q.d.) or placebo for 28 days. During treatment, study visits were performed on baseline (Day 1), Day 14, Day 28 and an additional follow-up visit on Day 56. Safety assessments were carried out at all visits to determine the primary endpoints. On Day 7 and Day 21 additional phone visits were carried out to assess concomitant meds and AEs. Primary endpoints were nature, frequency, severity, and timing of adverse and serious adverse events (AE/SAEs) and treatment discontinuation. Furthermore, standard laboratory values, electrocardiogram (ECG), electroencephalogram (EEG), magnetic resonance imaging (MRI), and vital signs were assessed. Secondary endpoints included the evaluation of pharmacokinetic characteristics of PRI-002 in plasma and the determination of cerebrospinal fluid (CSF) concentrations of PRI-002. The trial is registered in EudraCT 2020-003416-27 and clinicaltrials.gov NCT04711486 . In the study, 19 out of 20 patients were randomly assigned to PRI-002 (n = 9) or placebo (n = 10) and completed the study. One patient withdrew informed consent before randomization. All primary endpoints were met. Overall, the study drug was well tolerated. In total n = 16 AEs were reported in the verum group, while n = 27 AEs were noted in the placebo group. No SAEs were reported. No significant changes in clinical chemistry, hematology or hematoserology were detected. ECG, EEG and MRI revealed no changes and in detail no ARIA were observed. Pharmacokinetic parameters were unrelated to sex, age, and weight. Furthermore, no significant changes were detected in p-tau, t-tau, Aβ 1-40, Aβ 1-42 and Aβ oligomers in CSF. Patients receiving PRI-002 performed significantly better than those receiving placebo in the CERAD word list at Day 56 (P ≤ 0.05). In conclusion, 28 days of treatment with 300 mg q.d. PRI-002 was well tolerated in patients with MCI or mild dementia due to AD.

An orally available Cav2.2 calcium channel inhibitor for the treatment of neuropathic pain

BACKGROUND AND PURPOSE

Neuropathic pain affects up to 10% of the global population and is caused by an injury or a disease affecting the somatosensory, peripheral, or central nervous system. NP is characterized by chronic, severe and opioid-resistant properties. Therefore, its clinical management remains very challenging. The N-type voltage-gated calcium channel, Cav2.2, is a validated target for therapeutic intervention in chronic and neuropathic pain. The conotoxin ziconotide (Prialt®) is an FDA-approved drug that blocks Cav2.2 channel but needs to be administered intrathecally. Thus, although being principally efficient, the required application route is very much in disfavour.

EXPERIMENTAL APPROACH AND KEY RESULTS

Here, we describe an orally available drug candidate, RD2, which competes with ziconotide binding to Cav2.2 at nanomolar concentrations and inhibits Cav2.2 almost completely reversible. Other voltage-gated calcium channel subtypes, like Cav1.2 and Cav3.2, were affected by RD2 only at concentrations higher than 10 μM. Data from sciatic inflammatory neuritis rat model demonstrated the in vivo proof of concept, as low-dose RD2 (5 mg·kg-1) administered orally alleviated neuropathic pain compared with vehicle controls. High-dose RD2 (50 mg·kg-1) was necessary to reduce pain sensation in acute thermal response assessed by the tail flick test.

CONCLUSIONS AND IMPLICATIONS

Taken together, these results demonstrate that RD2 has antiallodynic properties. RD2 is orally available, which is the most convenient application form for patients and caregivers. The surprising and novel result from standard receptor screens opens the room for further optimization into new promising drug candidates, which address an unmet medical need.