Phase 1 Concentration-QTc and Cardiac Safety Analysis of the MDM2 Antagonist KRT-232 in Patients With Advanced Solid Tumors, Multiple Myeloma, or Acute Myeloid Leukemia.

Cardiac safety and plasma concentration-QTc interval analyses were completed using data from 2 phase 1 studies of the selective mouse double minute chromosome 2 antagonist, KRT-232, in patients with solid tumors or multiple myeloma and acute myeloid leukemia (AML) who received KRT-232 doses of 15 to 480 mg once daily (QD; N = 130). A linear mixed-effects model related change from baseline Fridericia-corrected QT interval (ΔQTcF) to KRT-232 plasma concentrations. The final model included parameters for the intercept (with between-subject variability), KRT-232 concentration-ΔQTcF slope, and baseline QTcF effect on the intercept. Diagnostic plots indicated an adequate model fit. Mean (90% confidence interval) predicted ΔQTcF values at the maximum clinical dose (480 mg QD) were 2.04 (0.49-3.60) milliseconds for patients with solid tumors and 4.52 (2.35-6.69) milliseconds for patients with AML. Because the 90% confidence interval upper bound of the mean ΔQTcF was predicted to be below 10 milliseconds at doses up to 480 mg QD in patients with solid tumors, multiple myeloma, or AML, KRT-232 does not result in clinically meaningful QT prolongation at the doses currently under investigation in clinical trials. No significant cardiac safety concerns were identified at these doses.

Intestinal and hepatic first-pass extraction of the 11ß-HSD1 inhibitor AMG 221 in rats with chronic vascular catheters.

1. A catheterized rat model was used to define the intestinal and hepatic components of oral bioavailability for an 11ß-HSD1 inhibitor, AMG 221. These data were integrated with standard in vivo metabolism studies to elucidate the components contributing to the oral disposition of a novel drug candidate. 2. Intestinal and hepatic extraction ratios of AMG 221 obtained using a five-catheter rat model were 0.56 and 0.32, respectively. Therefore, both intestinal and hepatic extraction contributed to the first-pass component of oral bioavailability. There was no evidence for significant gut extraction of systemically administered drug. 3. Mass balance data and in vivo metabolite characterization obtained after administration of [(14)C] AMG 221 to rat showed that AMG 221 was completely absorbed from the gut lumen following an oral dose, primarily excreted in urine and was almost completely metabolized prior to excretion. 4. Hepatic bioavailability (FH), measured in two animals at various time points after oral dose administration was somewhat variable but generally characterized by an initial reduction during the absorption phase followed by an increase during the elimination phase, consistent with hepatic distribution of AMG 221. 5. The five-catheter rat model afforded estimates of hepatic and intestinal contribution to oral bioavailability that were used with other data to define the preclinical ADME characteristics of a drug candidate.

Target-mediated metabolism and target-mediated drug disposition of the DPPIV inhibitor AMG 222.

Pharmacokinetic and metabolism aspects of AMG 222 interaction with target enzyme, dipeptidylpeptidase IV (DPPIV) were investigated. Inhibition of recombinant human DPPIV by AMG 222 was measured. IC(50) decreased as preincubation time increased. k(off), k(on) and K(d) were measured. Dilution assay indicated a long dissociation half-life (730 min) relative to DPPIV inhibitor vildagliptin. AMG 222 is a slow-on, tight-binding, slowly reversible inhibitor of DPPIV. Amide and acid metabolites arising from hydrolysis of AMG 222's cyano group were formed slowly by rhDPPIV, but not by microsomes or S9. The amide metabolite was converted to the acid metabolite by rhDPPIV, but not by an active site mutant. These metabolites of AMG 222 are formed by target-mediated metabolism of the cyano group, similar to vildagliptin. Human plasma protein binding of [(14)C]AMG 222 was saturable and concentration-dependent. After 30 min, [(14)C]AMG 222 was 80.8% bound at 1 nM and binding decreased to 29.4% above 100 nM. The plasma DPPIV concentration (4.1 nM) and human plasma AMG 222 concentrations that inhibit DPPIV, occurred in the range of concentration-dependent binding. Target-mediated drug disposition influences AMG 222 pharmacokinetics, similar to DPPIV inhibitor, linagliptin.