Pharmacokinetics of Gepotidacin in Subjects With Normal Hepatic Function and Hepatic Impairment.

Gepotidacin is a novel triazaacenaphthylene bacterial topoisomerase inhibitor. This phase 1 nonrandomized, open-label, multicenter, 2-part study evaluated the pharmacokinetics, safety, and tolerability of oral gepotidacin 1500 mg in 3 different hepatic settings (normal, moderate impairment, and severe impairment). Gepotidacin was safe and generally tolerated in all subjects. Compared to subjects with normal hepatic function, gepotidacin plasma area under the plasma concentration-time curve from time 0 to infinity (AUC0-∞ ) and maximum concentration significantly increased by 1.7- and 1.9-fold, respectively, in severe hepatic impairment; increases in moderate impairment were not statistically significant. No significant effect was observed for gepotidacin plasma elimination half-life (geometric mean range, 8.2-9.1 hours) across hepatic groups. Renal clearance increased in moderate (16%) and severe (52%) hepatic impairment vs normal. The mean fraction of gepotidacin dose excreted in urine increased with increasing hepatic impairment (normal, 7.5%; moderate, 11.2%; and severe, 19.9%). Urine gepotidacin concentrations remained high for 12 hours in all hepatic groups after dosing. Saliva gepotidacin concentrations displayed a linear relationship with plasma concentrations (R2 = 0.76). The ratio of saliva AUC to unbound plasma AUC and elimination half-life were not affected by hepatic impairment. These data indicate that gepotidacin dose adjustment is not required in mild to moderate hepatic impairment; severe hepatic impairment may require increases in dosing interval or dose reduction.

A Phase I, Randomized, Double-Blinded, Placebo- and Moxifloxacin-Controlled, Four-Period Crossover Study To Evaluate the Effect of Gepotidacin on Cardiac Conduction as Assessed by 12-Lead Electrocardiogram in Healthy Volunteers.

Gepotidacin is a novel, first-in-class triazaacenaphthylene antibiotic in development for treatment of conventional and biothreat infections. This was a single-dose, crossover thorough QT study in healthy subjects who were administered intravenous (i.v.) gepotidacin as a therapeutic (1,000-mg) dose and supratherapeutic (1,800-mg) dose, placebo, and 400 mg oral moxifloxacin in 4 separate treatment periods. Gepotidacin caused a mild effect on heart rate, with a largest placebo-corrected change-from-baseline heart rate of 7 and 10 beats per minute at the end of the 1,000-mg and 1,800-mg infusion, respectively. Gepotidacin caused an increase of change-from-baseline QTcF (ΔQTcF), with a peak effect at the end of infusion. The largest mean placebo-corrected ΔQTcF (ΔΔQTcF) was 12.1 ms (90% confidence interval [CI], 9.5 to 14.8) and 22.2 ms (90% CI, 19.6 to 24.9) after 1,000 mg and 1,800 mg, respectively. ΔΔQTcF rapidly fell after the end of the infusion, with a mean ΔΔQTcF of 6.1 ms 60 min after the 1,800-mg dose. Exposure-response analysis demonstrated a statistically significant positive relationship between gepotidacin plasma levels and ΔΔQTcF, with a slope of 1.45 ms per µg/ml (90% CI, 1.30 to 1.61). Using this model, the effect on ΔΔQTcF can be predicted to be 11 and 20 ms at the observed mean peak plasma concentration after the infusion of gepotidacin at 1,000 mg (7 µg/ml) and 1,800 mg (13 µg/ml), respectively. In conclusion, gepotidacin caused QT prolongation in this thorough QT study, and a mean effect can be predicted to less than 15 ms at the highest expected plasma concentration, 9 µg/ml. (This study has been registered at ClinicalTrials.gov under identifier NCT02257398.).

An antiapoptotic Bcl-2 family protein index predicts the response of leukaemic cells to the pan-Bcl-2 inhibitor S1.

BACKGROUND: Bcl-2-like members have been found to be inherently overexpressed in many types of haematologic malignancies. The small-molecule S1 is a BH3 mimetic and a triple inhibitor of Bcl-2, Mcl-1 and Bcl-XL. METHODS: The lethal dose 50 (LD(50)) values of S1 in five leukaemic cell lines and 41 newly diagnosed leukaemia samples were tested. The levels of Bcl-2 family members and phosphorylated Bcl-2 were semiquantitatively measured by western blotting. The interactions between Bcl-2 family members were tested by co-immunoprecipitation. The correlation between the LD(50) and expression levels of Bcl-2 family members, alone or in combination, was analysed. RESULTS: S1 exhibited variable sensitivity with LD(50) values ranging >2 logs in both established and primary leukaemic cells. The ratio of pBcl-2/(Bcl-2+Mcl-1) could predict the S1 response. Furthermore, we demonstrated that pBcl-2 antagonised S1 by sequestering the Bak and Bim proteins that were released from Mcl-1, andpBcl-2/Bak, pBcl-2/Bax and pBcl-2/Bim complexes cannot be disrupted by S1. CONCLUSION: A predictive index was obtained for the novel BH3 mimetic S1. The shift of proapoptotic proteins from being complexed with Mcl-1 to being complexed with pBcl-2 was revealed for the first time, which is the mechanism underlying the index value described herein.

Phase I pharmacokinetic and pharmacodynamic study of triciribine phosphate monohydrate, a small-molecule inhibitor of AKT phosphorylation, in adult subjects with solid tumors containing activated AKT.

PURPOSE: Triciribine phosphate is a potent, small-molecule inhibitor of activation of all three isoforms of AKT in vitro. AKT is an intracellular protein that, when activated, leads to cellular division; it is dysregulated in a large number of malignancies, and constitutively activating AKT mutations are present in a minority of cancers. PATIENTS AND METHODS: In this phase I study triciribine phosphate monohydrate (TCN-PM) was administered to subjects whose tumors displayed evidence of increased AKT phosphorylation (p-AKT) as measured by immunohistochemical analysis (IHC). TCN-PM was administered over 30 min on days 1, 8 and 15 of a 28-day cycle. Tumor biopsy specimens, collected before treatment and on day +15, were assessed for p-AKT by IHC and western blot analyses. RESULTS: Nineteen subjects were enrolled; 13 received at least one cycle of therapy, and a total of 34 complete cycles were delivered. One subject was treated at the 45 mg/m(2) dose before the study was closed due to its primary objective having been met. No dose-limiting toxic effects were observed. Modest decreases in tumor p-AKT following therapy with TCN-PM were observed at the 35 mg/m(2) and 45 mg/m(2) dose levels, although definitive conclusions were limited by the small sample size. CONCLUSIONS: These preliminary data suggest that treatment with TCN-PM inhibits tumor p-AKT at doses that were tolerable. Although single agent activity was not observed in this enriched population, further combination studies of TCN-PM with other signal transduction pathway inhibitors in solid tumors is warranted.