A phase I study of panobinostat in pediatric patients with refractory solid tumors, including CNS tumors.

<bold>Purpose: </bold>This was an open label, phase I (3 + 3 design), multi-centre study evaluating panobinostat in pediatric patients with refractory solid tumors.<bold>Methods: </bold>Primary endpoints were to establish MTD, define and describe associated toxicities, including dose limiting toxicities (DLT) and to characterize its pharmacokinetics (PK). Secondary endpoints included assessing the anti-tumour activity of panobinostat, and its biologic activity, by measuring acetylation of histones in peripheral blood mononuclear cells.<bold>Results: </bold>Nine patients were enrolled and treated with intravenous panobinostat at a dosing level of 15 mg/m2 which was tolerated. Six were evaluable for adverse events. Two (33%) patients experienced Grade 3-4 thrombocytopenia, 1 (17%) experienced Grade 3 anemia, and 2 (33%) experienced Grade 3 neutropenia. Grade 4 drug related pain occurred in 2 (33%) of the patients studied. Two (33%) patients experienced a Grade 2 QTcF change (0.478 ± 0.006 ms). One cardiac DLT (T wave changes) was reported. PK values for 15 mg/m2 (n = 9) dosing were: Tmax 0.8 h, Cmax 235.2 ng/mL, AUC0-t 346.8 h ng/mL and t1/2 7.3 h. Panobinostat significantly induced acetylation of histone H3 and H4 at all time points measured when compared to pre-treatment samples (p < 0.05). Pooled quantitative Western blot data confirmed that panobinostat significantly induced acetylation of histone H4 at 6 h (p < 0.01), 24 h (p < 0.01) and 28-70 h (p < 0.01) post dose.<bold>Conclusion: </bold>A significant biological effect of panobinostat, measured by acetylation status of histone H3 and H4, was achieved at a dose of 15 mg/m2. PK data and drug tolerability at 15 mg/m2 was similar to that previously published. [ABSTRACT FROM AUTHOR]