OBJECTIVE The pan-
histone deacetylase inhibitor panobinostat has preclinical efficacy against
diffuse intrinsic pontine glioma (
DIPG), and the oral formulation has entered a Phase I clinical trial. However,
panobinostat does not cross the blood-brain barrier in humans. Convection-enhanced delivery (CED) is a novel neurosurgical
drug delivery technique that bypasses the blood-brain barrier and is of considerable clinical interest in the treatment of
DIPG. METHODS The authors investigated the toxicity, distribution, and clearance of a water-soluble formulation of
panobinostat (MTX110) in a small- and large-animal model of CED. Juvenile male Wistar rats (n = 24) received
panobinostat administered to the pons by CED at increasing concentrations and findings were compared to those in animals that received vehicle alone (n = 12). Clinical observation continued for 2 weeks. Animals were sacrificed at 72 hours or 2 weeks following treatment, and the brains were subjected to neuropathological analysis. A further 8 animals received
panobinostat by CED to the striatum and were sacrificed 0, 2, 6, or 24 hours after infusion, and their brains explanted and snap-frozen. Tissue-
drug concentration was determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). Large-animal toxicity was investigated using a clinically relevant MRI-guided translational porcine model of CED in which a drug delivery system designed for humans was used.
Panobinostat was administered at 30 μM to the ventral pons of 2 juvenile Large White-Landrace cross pigs. The animals were subjected to clinical and neuropathological analysis, and findings were compared to those obtained in controls after either 1 or 2 weeks.
Drug distribution was determined by LC-MS/MS in porcine white and gray matter immediately after CED. RESULTS There were no clinical or neuropathological signs of toxicity up to an infused concentration of 30 μM in both small- and large-animal models. The half-life of
panobinostat in rat brain after CED was 2.9 hours, and the
drug was observed to be distributed in porcine white and gray matter with a volume infusion/distribution ratio of 2 and 3, respectively. CONCLUSIONS CED of water-soluble
panobinostat, up to a concentration of 30 μM, was not toxic and was distributed effectively in normal brain. CED of
panobinostat warrants clinical investigation in patients with
DIPG.