Discovery of VU6024578/BI02982816: An mGlu1 Positive Allosteric Modulator with Efficacy in Preclinical Antipsychotic and Cognition Models

Abstract

Herein, we report progress toward a metabotropic glutamate receptor subtype 1 (mGlu₁) positive allosteric modulator (PAM) clinical candidate and the discovery of VU6024578/BI02982816. From a weak high-throughput screening hit (VU0538160, EC₅₀ > 10 μM, 71% Glu_max), optimization efforts improved functional potency over 185-fold to deliver the selective (inactive on mGlu_2-5,7,8) and CNS penetrant (rat K_p = 0.99, K_p,uu = 0.82; MDCK-MDR1 ER = 1.7, P_app = 73 × 10-6 cm/s) mGlu₁ PAM (VU6024578/BI02982816, EC₅₀ = 54 nM, 83% Glu_max). An excellent rat pharmacokinetic profile allowed the evaluation of VU6024578/BI02982816 in both amphetamine-induced hyperlocomotion (minimum effective dose (MED) = 3 mg/kg, p.o.) and MK-801 induced disruptions of novel object recognition (MED = 10 mg/kg p.o.), thus providing efficacy in preclinical models of psychosis and cognition. However, unanticipated AEs in dog prevented further consideration as a candidate. Thus, VU6024578/BI02982816 can serve as a best-in-class in vivo rodent tool to study selective mGlu₁ activation.

Figure 1

Structures of exemplar in vitro and in vivo mGlu₁ PAM tool compounds 1-5, highlighting the limited chemical diversity.

Figure 2

Structure of HTS hit 6 (VU0538160), a weak but chemically distinct mGlu₁ PAM hit.

Scheme 1. Synthesis of Analogs 9

Scheme 2. Synthesis of Analogs 15a-f

Scheme 3. Synthesis of Analogs 19

Scheme 4. Optimized Synthesis of 19d

Figure 3

Triple-Add primary mGlu₁ assay CRCs of 19d. A) The agonist (or compound alone window) indicating no intrinsic agonist activity. B) The PAM (EC₂₀) window, showing a robust PAM CRC. C) The antagonist (EC₈₀) window, displaying little receptor desensitization.

Figure 4

Operational modeling of the effects of increasing concentrations of VU6024578 (19d) on rat (A) and human (B) mGlu₁receptors. Increasing amounts of 19d were applied prior to increasing concentrations of glutamate at either rat or human mGlu₁. Data were fit in GraphPad Prism as indicated in the Methods section; for panel A, log α was 0.95 and for panel B it was 1.26. Data represent one experiment performed in duplicate.

Figure 5

Metabolite identification of VU6024578 (19d) in rat and human liver microsomes. VU6024578–03 (19d) was the major component observed in the rat and human 60 min samples (with and without NADPH) based on UV peak areas (as well as by extracted ion). Thus, we incubated 19d in rat and human liver microsomes (with and without NADPH) for 60 min and monitored by both extracted ion and UV detection for the production of metabolites and consumption of parent.

Figure 6

Rat MK-801 induced disruption of novel object recognition and reversal by VU6024578 (19d). MK-801 (0.5 mg/kg IP) induced a robust disruption of NOR, which was dose-dependently reversed by oral administration (10% tween 80) of 19d.

Figure 7

Rat amphetamine-induced hyperlocomotion and reversal by VU6024578 (19d). Amphetamine (0.75 mg/kg IP) induced robust hyperlocomotion, which was dose-dependently reversed by oral administration (10% tween 80) of 19d.

Figure 8

Mouse amphetamine-induced hyperlocomotion and reversal by VU6024578 (19d). Amphetamine (3.0 mg/kg s.c.) induced robust hyperlocomotion, which was dose-dependently reversed by oral administration (0.5% Natrasol/0.015% tween 80 in H₂O) of 19d.

Figure 9

Study design for Amphetamine-induced hyperlocomotion C_max versus C_trough study.

Figure 10

Amphetamine-induced hyperlocomotion in rats. A) 1 h pretreatment of 3 mg/kg 19d. B) 5 h pretreatment of 10 mg/kg 19d. C) 28.5 h pretreatment of 60 mg/kg 19d. Total ambulation from 95 to 180 min. *p < 0.05 compared to Vehicle + Amphetamine treated animals.

Figure 11

Effects of compound 19d (1, 10 mg/kg, p.o., n = 14) on motor activity, body temperature, sleep-wake profile and EEG brain activity of rats: A) motors activity, B) body activity, C) vigilance states assessment and D), EEG power spectra. Data are expressed as mean ± SEM and were analyzed by one- and two-way ANOVA followed by Dunnett’s Multiple Comparisons tests (*p < 0.05, **p < 0.01, ***p < 0.001 versus vehicle).

Figure 12

Modulation of auditory event related potentials in C57BL/6JRj mice following s.c. administration of different doses of compound 19d. The mGlu2/3 selective agonist LY379268 was used here as a positive control, applied also s.c. at 3 mg/kg dose. Effects of 0.8, 4, and 10 mg/kg compound 19d on ASSR 40 Hz Phase-lock coherence (A) and N1 gating (B) measured in prefrontal cortex were analyzed and compared to mice treated with MK-801 0.12 mg/kg or vehicle. Data are shown as mean ± SEM (n = 13–19 for each treatment group). *P < 0.05, **P < 0.01, ***P < 0.005 compared with vehicle; #P < 0.05, ##P < 0.01 compared with MK-801.