Dose selection for intracerebroventricular cerliponase alfa in children with CLN2 disease, translation from animal to human in a rare genetic disease.

Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is an ultra-rare pediatric neurodegenerative disorder characterized by deficiency of the lysosomal enzyme tripeptidyl peptidase-1 (TPP1). In the absence of adequate TPP1, lysosomal storage material accumulation occurs in the central nervous system (CNS) accompanied by neurodegeneration and neurological decline that culminates in childhood death. Cerliponase alfa is a recombinant human TPP1 enzyme replacement therapy administered via intracerebroventricular infusion and approved for the treatment of CLN2 disease. Here, we describe two allometric methods, calculated by scaling brain mass across species, that informed the human dose selection and exposure prediction of cerliponase alfa from preclinical studies in monkeys and a dog model of CLN2 disease: (1) scaling of dose using a human-equivalent dose factor; and (2) scaling of compartmental pharmacokinetic (PK) model parameters. Source PK data were obtained from cerebrospinal fluid (CSF) samples from dogs and monkeys, and the human exposure predictions were confirmed with CSF data from the first-in-human clinical study. Nonclinical and clinical data were analyzed using noncompartmental analysis and nonlinear mixed-effect modeling approaches. Both allometric methods produced CSF exposure predictions within twofold of the observed exposure parameters maximum plasma concentration (Cmax ) and area under the curve (AUC). Furthermore, cross-species qualification produced consistent and reasonable PK profile predictions, which supported the allometric scaling of model parameters. The challenges faced in orphan drug development place an increased importance on, and opportunity for, data translation from research and nonclinical development. Our approach to dose translation and human exposure prediction for cerliponase alfa may be applicable to other CNS administered therapies being developed.

Sensitive method for the quantitative determination of gemfibrozil in dog plasma by liquid-liquid cartridge extraction and liquid chromatography-tandem mass spectrometry.

A sensitive LC-MS/MS assay for the quantitative determination of gemfibrozil in dog plasma has been developed and validated and is described in this work. The assay involved the extraction of the analyte from 0.5-ml aliquots of dog plasma using Chem Elut cartridges and methyl tert.-butyl ether (MTBE). Chromatography was performed on a Metasil Basic column (50 x 2 mm I.D., 3 microm) using a mobile phase that consisted of 70:30 acetonitrile-ammonium acetate (1 mM, pH 5.0) with a flow-rate of 0.2 ml min(-1). The method showed excellent reproducibility with an inter- and intra-assay precision of <8.9% (%RSD), as well as excellent accuracy with an inter- and intra-assay accuracy between 99 and 101%. This method has a lower limit of quantitation (LLOQ) of 1.0 ng ml(-1) with a linear calibration range from 1.0 to 250 ng ml(-1). This new assay offers higher sensitivity and a much shorter run time over earlier methods.