Relative bioavailability and food effect study of an oral suspension of alectinib in healthy volunteers using venipuncture and capillary microsampling.

Alectinib, approved as 150 mg capsules for the treatment of adults with advanced ALK-positive non-small cell lung cancer, is being assessed in children with ALK-positive solid and central nervous system tumors. An ad hoc pediatric-friendly suspension of alectinib, prepared from capsule contents, is under investigation as an alternative formulation for children who cannot swallow capsules. This randomized, crossover, relative bioavailability, and food effect study evaluated alectinib administered as an oral suspension versus capsule formulation following conventional venipuncture and capillary microsampling. A total of 28 healthy adult subjects received a 600 mg single dose of alectinib in two groups: fasted (n = 14) and mixed fed (n = 14; seven receiving high-fat meal and seven receiving low-fat meal). Combined alectinib + M4 (active metabolite) exposure was higher for suspension versus capsule, with geometric mean ratio (GMR) of 2.6 for area under the concentration-time curve extrapolated to infinity (AUC0-∞ ) and 3.0 for maximum observed concentration (Cmax ) under fasted conditions, and 1.7 for both parameters for mixed fed. The suspension showed increased alectinib + M4 AUC0-∞ following a high-fat meal versus fasted conditions (GMR 1.7 [90% confidence interval 1.4-2.2]). Alectinib AUC0-∞ and Cmax measured in venous and capillary samples were generally similar for the suspension and capsule. Single oral doses of 600 mg alectinib suspension and capsule were well tolerated, with no safety concerns. Based on these findings, the oral suspension of alectinib appears suitable for use in pediatric studies after appropriate dose adjustment relative to the capsule.

Defective tumor necrosis factor-alpha-dependent control of astrocyte glutamate release in a transgenic mouse model of Alzheimer disease.

The cytokine tumor necrosis factor-alpha (TNFalpha) induces Ca2+-dependent glutamate release from astrocytes via the downstream action of prostaglandin (PG) E2. By this process, astrocytes may participate in intercellular communication and neuromodulation. Acute inflammation in vitro, induced by adding reactive microglia to astrocyte cultures, enhances TNFalpha production and amplifies glutamate release, switching the pathway into a neurodamaging cascade (Bezzi, P., Domercq, M., Brambilla, L., Galli, R., Schols, D., De Clercq, E., Vescovi, A., Bagetta, G., Kollias, G., Meldolesi, J., and Volterra, A. (2001) Nat. Neurosci. 4, 702-710). Because glial inflammation is a component of Alzheimer disease (AD) and TNFalpha is overexpressed in AD brains, we investigated possible alterations of the cytokine-dependent pathway in PDAPP mice, a transgenic model of AD. Glutamate release was measured in acute hippocampal and cerebellar slices from mice at early (4-month-old) and late (12-month-old) disease stages in comparison with age-matched controls. Surprisingly, TNFalpha-evoked glutamate release, normal in 4-month-old PDAPP mice, was dramatically reduced in the hippocampus of 12-month-old animals. This defect correlated with the presence of numerous beta-amyloid deposits and hypertrophic astrocytes. In contrast, release was normal in cerebellum, a region devoid of beta-amyloid deposition and astrocytosis. The Ca2+-dependent process by which TNFalpha evokes glutamate release in acute slices is distinct from synaptic release and displays properties identical to those observed in cultured astrocytes, notably PG dependence. However, prostaglandin E2 induced normal glutamate release responses in 12-month-old PDAPP mice, suggesting that the pathology-associated defect involves the TNFalpha-dependent control of secretion rather than the secretory process itself. Reduced expression of DENN/MADD, a mediator of TNFalpha-PG coupling, might account for the defect. Alteration of this neuromodulatory astrocytic pathway is described here for the first time in relation to Alzheimer disease.