Cell experiment:

SH-SY5Y-APP cells, Tg2576 mixed brain cultures, or C57 mixed brain cultures are treated with various concentrations of NGP555 in triplicate wells, for 18 hours. Media is collected and analyzed for Aβ peptides using triplex ELISA (Aβ38 and Aβ42)[1].

Animal experiment:

For CSF studies, Normal Sprague-Dawley male rats (250 to 300 g) are administered NGP555 in 80% PEG orally or vehicle only, n=10/group. Rats are dosed once-daily for a single-dose or 14 days of dosing. After the final dose, cerebrospinal fluid (CSF) samples are either collected at varying time points or a single time point post-last dose. Rats are deeply anesthetized with isoflurane, and CSF is collected from the cisterna magna. Samples are tested for Aβ level. For Y-maze study, transgenic mice (Tg2576 line expressing the APP-Swe mutation) and non-transgenic age-matched littermates (n=a minimum of 12/group) are treated with vehicle, NGP555 (25 mg/kg) once-daily for 30 consecutive days (starting at 5 months of age). At 6 months, mice are assessed on the Y-maze behavior test[1].

NGP555 is a γ-secretase modulator.

NGP555 potently lowers Aβ42 in cell cultures (9 nM) while increasing shorter forms of Aβ[1].

NGP555 significantly lowers Aβ42 in the cerebrospinal fluid (CSF) at time points from 8 to10 hours post dose, panel B shows that reduction of Aβ cerebrospinal fluid (CSF) levels is significant at 3.75 mg/kg of NGP555 and above, and panel C shows an increase in Aβ38 levels at 15 mg/kg of NGP555 and above. When combining the reduction of Aβ42 with an increase in Aβ38, NGP555 is effective at raising CSF Aβ38/42 ratio at 1.87 mg/kg and above (panel D). NGP555-treated Tg mice show a significant protection from decline in performance with >65% less decline (P<0.005) when comparing the differential of Tg to non-Tg vehicle-treated mice. NGP555 also shows good oral bioavailability and is brain-penetrant with a brain:plasma ratio of ~0.93 in mice[1].

[1]. Kounnas MZ, et al. NGP 555, a γ-Secretase Modulator, Lowers the Amyloid Biomarker, Aβ42, in Cerebrospinal Fluid while Preventing Alzheimer's Disease Cognitive Decline in Rodents. Alzheimers Dement (N Y). 2017 Jan;3(1):65-73.