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We started with a medium throughput screen of heterocyclic compounds without basic amine groups to avoid hERG and β-blocker activity and identified [1,2,4]triazolo[4,3-a]pyridine as an early lead. Optimization of substituents for Late INa current inhibition and lack of Peak INa inhibition led to the discovery of 4h (GS-458967) with improved anti-arrhythmic activity relative to ranolazine. Unfortunately, 4h demonstrated use dependent block across the sodium isoforms including the central and peripheral nervous system isoforms that is consistent with its low therapeutic index (approximately 5-fold in rat, 3-fold in dog). Compound 4h represents our initial foray into a 2nd generation Late INa inhibitor program and is an important proof-of-concept compound. We will provide additional reports on addressing the CNS challenge in a follow-up communication.

We hereby disclose the discovery of inhibitors of CaMKII (7h and 7i) that are highly potent in rat ventricular myocytes, selective against hERG and other off-target kinases, while possessing good CaMKII tissue isoform selectivity (cardiac γ/δ vs. neuronal α/β). In vitro and in vivo ADME/PK studies demonstrated the suitability of these CaMKII inhibitors for PO (7h rat F = 73%) and IV pharmacological studies.

We identified a series of structurally novel SCD (Delta9 desaturase) inhibitors via high-throughput screening and follow-up SAR studies. Modification of the central bicyclic scaffold has proven key to our potency optimization effort. The most potent analog (8g) had IC(50) value of 50 pM in a HEPG2 SCD assay and has been shown to be metabolically stable and selective against Delta5 and Delta6 desaturases.

We discovered a structurally novel SCD (Delta9 desaturase) inhibitor 4a (CVT-11,563) that has 119 nM potency in a human cell-based (HEPG2) SCD assay and selectivity against Delta5 and Delta6 desaturases. This compound has 90% oral bioavailability (rat) and excellent plasma exposure (dAUC 935 ng h/mL). Additionally, 4a shows moderately selective liver distribution (three times vs plasma and adipose tissue) and relatively low brain penetration. In a five-day study (high sucrose diet, rat) compound 4a significantly reduced SCD activity as determined by GC analysis of fatty acid composition in plasma and liver. We describe the discovery of 4a from HTS hit 1 followed by scaffold replacement and SAR studies focused on DMPK properties.