John Anthony Moliterni

Preclinical In vivo Evaluation of Efficacy, Pharmacokinetics, and Pharmacodynamics of a Novel MEK1/2 Kinase Inhibitor RO5068760 in Multiple Tumor Models

Targeting the Ras/Raf/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway represents a promising anticancer strategy. Recently, we have reported a novel class of potent and selective non–ATP-competitive MEK1/2 inhibitors with a unique structure and mechanism of action. RO5068760 is a representative of this class showing significant efficacy in a broad spectrum of tumors with aberrant mitogen-activated protein kinase pathway activation. To understand the relationship between systemic exposures and target (MEK1/2) inhibition as well as tumor growth inhibition, the current study presents a detailed in vivo characterization of efficacy, pharmacokinetics, and pharmacodynamics of RO5068760 in multiple xenograft tumor models. For inhibition of MEK1/2 as measured by the phosphorylated ERK levels, the estimated EC50s in plasma were 1.36 μmol/L (880 ng/mL) and 3.35 μmol/L (2168 ng/mL) in LOX melanoma and HT-29 colorectal cancer models, respectively. A similar EC50 (1.41 μmol/L or 915 ng/mL) was observed in monkey peripheral blood lymphocytes. To achieve tumor growth inhibition (≥90%), an average plasma drug concentration of 0.65 or 5.23 μmol/L was required in B-RafV600E or K-Ras mutant tumor models, respectively, which were remarkably similar to the IC90 values (0.64 or 4.1 μmol/L) determined in vitro for cellular growth inhibition. With equivalent in vivo systemic exposures, RO5068760 showed superior efficacy in tumors harboring B-RafV600E mutation. The plasma concentration time profiles indicate that constant p-ERK suppression (>50%) may not be required for optimal efficacy, especially in highly responsive tumors. This study may facilitate future clinical trial design in using biochemical markers for early proof of mechanism and in selecting the right patients and optimal dose regimen. Mol Cancer Ther; 9(1); 134–44

Benzazepinones and benzoxazepinones as antagonists of inhibitor of apoptosis proteins (IAPs) selective for the second baculovirus IAP repeat (BIR2) domain.

XIAP is a key regulator of apoptosis, and its overexpression in cancer cells may contribute to their survival. The antiapoptotic function of XIAP derives from its BIR domains, which bind to and inhibit pro-apoptotic caspases. Most known IAP inhibitors are selective for the BIR3 domain and bind to cIAP1 and cIAP2 as well as XIAP. Pathways activated upon cIAP binding contribute to the function of these compounds. Inhibitors selective for XIAP should exert pro-apoptotic effects through competition with the terminal caspases. This paper details our synthetic explorations of a novel XIAP BIR2-selective benzazepinone screening hit with a focus on increasing BIR2 potency and overcoming high in vivo clearance. These efforts led to the discovery of benzoxazepinone 40, a potent BIR2-selective inhibitor with good in vivo pharmacokinetic properties which potentiates apoptotic signaling in a manner mechanistically distinct from that of known pan-IAP inhibitors.

CGS 27830, a potent nonpeptide endothelin receptor antagonist

Abstract Treatment of the dihydropyridine carboxylic acid 1 with EDCI produced a diastereomeric mixture of chemically stable anhydrides. The meso-isomer, CGS 27830, was isolated by crystallization and found to be a potent (16 nM) endothelin receptor antagonist for the ETA receptor subtype.

Optimization of Benzodiazepinones as Selective Inhibitors of the X-Linked Inhibitor of Apoptosis Protein (XIAP) Second Baculovirus IAP Repeat (BIR2) Domain

The IAPs are key regulators of the apoptotic pathways and are commonly overexpressed in many cancer cells. IAPs contain one to three BIR domains that are crucial for their inhibitory function. The pro-survival properties of XIAP come from binding of the BIR domains to the pro-apoptotic caspases. The BIR3 domain of XIAP binds and inhibits caspase 9, while the BIR2 domain binds and inhibits the terminal caspases 3 and 7. While XIAP BIR3 inhibitors have previously been reported, they also inhibit cIAP1/2 and promote the release of TNFα, potentially limiting their therapeutic utility. This paper will focus on the optimization of selective XIAP BIR2 inhibitors leading to the discovery of highly potent benzodiazepinone 36 (IC50 = 45 nM), which has high levels of selectivity over XIAP BIR3 and cIAP1 BIR2/3 and shows efficacy in a xenograft pharmacodynamic model monitoring caspase activity while not promoting the release of TNFα in vitro.

The scope and limitations of the Suzuki–Miyaura cross-coupling reactions of 6- and 8-substituted 1,2,3,4-tetrahydroisoquinoline-3-carboxylates

Abstract 6- and 8-Aryl-1,2,3,4-tetrahydroisoqinoline-3-carboxylates have been prepared by Suzuki–Miyaura cross-coupling reactions of the triflates or corresponding boronate esters. We have shown for the first time that a one-pot arylation of a triflate via the boronate ester can be achieved using an aryl chloride.

Synthesis of tetrazole analogs of α-amino acids by alkylation of a Schiff base of α-aminomethyltetrazole

Abstract A benzophenone imine of N-1 protected α-aminomethyltetrazoles was found to undergo alkylation with organic halides in good yields. Deprotection afforded tetrazole analogs of α-amino acids.