Discovery of ONO-TR-772 (VU6018042): A Highly Selective and CNS Penetrant TREK Inhibitor in Vivo Tool Compound

Abstract

Herein we describe our continuing work on the K₂P family of potassium ion channels with the chemical optimization of a selective and CNS penetrant series of TREK inhibitors, culminating in the discovery of ONO-TR-772 (VU6018042). From an HTS hit harboring a benzyl ether linker, SAR proved intractable until an acetylene linker was identified as an isosteric replacement. Robust SAR was then observed, and a key fluorination to enhance PK and CNS penetration provided ONO-TR-772 (VU6018042), a potent (TREK-1 IC₅₀ = 15 nM), selective (>10 μM versus other K₂P channels except TREK-2), and CNS penetrant (rat K _p = 0.98) TREK inhibitor. ONO-TR-772 (VU6018042) demonstrated robust efficacy in an MK-801 challenge NOR paradigm, with an MED of 10 mg/kg.

Figure 1

Structures of reported TREK-1 and TREK-2 activators 1 and 2, and the more recently developed TREK-1 inhibitors 3 and 4.

Figure 2

Structures of the HTS hit 5, and a rapid hit expansion exercise improved potency ∼17-fold to afford submicromolar TREK-1 lead 6.

Scheme 1. Synthesis of Heteroaryl Analogues 10

Reagents and conditions: (a) BnBr, Cs₂CO₃, DMF, rt, 12%; (b) 5-(tert-butoxycarbonylamino)-2-chlorobenzoic acid, DIEA, DMF, HBTU, rt to 60 °C, 18%; (c) BnOH, DIAD, PPh₃, THF, rt, 24%; (d) Fe, NH₄Cl, THF, H₂O, 75 °C, 87%; (e) 5-(tert-butoxycarbonylamino)-2-chlorobenzoic acid, DIEA, DCM, T₃P, rt, 42%; (f) BnOH, NaH, 0–120 °C, 34%; (g) 5-(tert-butoxycarbonylamino)-2-chlorobenzoic acid, DIEA, DCM, T₃P, rt, 26%.

Figure 3

Impact of replacement of the benzyl ether with an acetylene moiety on both TREK-1 potency and in vitro and in vivo clearance.

Figure 4

Effect of 14c (ONO-TR-772/VU6018042) in the MK-801 challenged novel object recognition task. 14c dose-dependently enhanced recognition memory in male CD-1 mice after challenged with MK-801. Pretreatment with 3, 10, and 30 mg/kg 14c IP 3.5 h prior to MK-801 treatment and exposure to identical objects significantly enhanced recognition memory assessed 90 min later. Minimum effective dose (MED) is 10 mg/kg. N = 15/group of male CD-1 mice. # p < 0.05, ###, p < 0.001 vs normal (t test), **p < 0.01; ***p < 0.001 vs vehicle (Dunnett posthoc test). †††, p < 0.001 vehicle group (t test).

Figure 5

Cyclopropyl amides are viable replacements for the N-Boc moiety. Introduction of the 4-F phenyl moiety reduces in vivo rat clearance almost 10-fold.