PROPOSAL: Translational Safety Biomarker Assessment of Neurotoxicity Andreas Jeromin, PhD Chief Scientific Officer NextGen Sciences DX Boston, MA Emerging Issues Session HESI Annual Meeting 12 June 2012 Prague, Czech Republic
Objective Develop an understanding of the importance of fluid-based biomarkers as translational safety biomarkers used in addition to current assessment tools (histology). Attrition and adverse side-effects of drugs in clinical development due to neurotoxicity amount up to 25% Comparable to nephro- and hepatotoxicity Not restricted to CNS-targeted drugs
Current gaps in the assessment of neurotoxicity Lack of sensitivity and quantitative nature of histology (Dosing) Spatial restrictions in sampling (8 coronal sections, CNS vs. PNS) Invasive nature of sampling and lack of longitudinal measurements Lack of translational character from preclinical to clinical
Why new safety biomarkers? Translational biomarkers for early clinical safety Minimally invasive for longitudinal assessment Increased understanding of toxicological mechanism Target engagement understanding of toxicity mechanisms Earlier decision making and de-risking Potential to speed up non-clinical drug safety Animal models not always predictive of toxicity in humans Current endpoints related to late stage effects Drug attrition often related to toxicity/safety
Training Set Neurotoxicants and Their Known Targets Toxicant Regional Target Cellular Target Subcellular Target TMT Limbic Structures Neurons Perikarya MK-801 Cortex Neurons Perikarya? Kainate Limbic Structures Neurons Perikarya MPTP Neostriatum Nigral-Striatal Dopamine Neurons Bilirubin Cerebellum Purkinje Cells Perikarya Cadmium Striatum Neurons, Gila? Dopaminergic Nerve Terminals 6-OH DA Neostriatum Dopamine Neurons Terminals and Perikarya 5,7-DHT Cortex, Hippocampus Striatum 5-HT Neurons 5-HT Nerve Terminals Perikarya Colchicine Hippocampus Dentate Neurons Perikarya 3-Acetyl Pyridine Inferior Olive Neurons Perikarya Methamphetamine Neostriatum Dopamine Neurons Dopamine Nerve Terminals IDPN Brain Stem Neurons Neurofilaments
Relative opportunity for detection Acute Cell Death Disintegration Timeline Axon Terminals Dendrites Cell Bodies Axons 0 1 2 3 4 5 6 7 8 9 Days post-administration After cell death detection is no longer possible, the debris from axon degeneration can still be detected (from Robert Switzer)
Fluid-based biomarker of neurotoxicity Increasing body of scientific literature and evidence for fluid-based biomarkers of neurotoxicity Immunoassay-based measurements of brain-injury biomarkers Development of multiplexed (up to 130 proteins/peptides) validated multiplereaction monitoring-based assays
Classical Stains Don t Reveal Subtle Damage Provided by James O Callaghan, CDC
FIGURE 5 TIME COURSE AND LOCATION OF GFAP INDUCTION FOLLOWING TREATMENT WITH MPTP GFAP mrna GFAP protein GFAP protein A 0 4 8 12 16 * B C * D SAL 2h 4h 6h 12h 24h * 0 200 400 SAL 2h 4h 6h 12h 24h 72h * 0 200 400 600 CER CTX HIP HYP STR * The dopaminergic neurotoxicant, MPTP, results in a rapid induction of astrogliosis in the affected region of mouse brain (striatum). (A) Immunohistochemical analysis of GFAP reveals a time-dependent astrogliosis following MPTP (12.5 mg/kg, s.c.). (B, C) Levels of GFAP mrna ( ) and protein ( ) were measured in striatum by TaqMan real-time PCR or sandwich ELISA and are represented as fold or % increase over corresponding saline-treated controls, respectively. (D) GFAP protein levels in various brain regions (CER= cerebellum;ctx= cortex; HIP= hippocampus; HYP= hypothalamus, STR= striatum) of saline ( ) or MPTP ( ) treated mice, 48h post MPTP. provided by James O Callaghan
Biomarkers of neurotoxic mechanisms Neuroregeneration Markers (CRMP-2) Axonal injury /Cell Death Markers (SBDP150, 145-Necrosis, SBDP 120-Apoptosis) Gliosis Markers (GFAP, S100B) Cell body-ptm Damage Markers (UCH-L1, GAPDH) Microgliosis Markers (EMAP-II, IL-6 / IL-10) Demyelination Markers (MBP-BDP) Synaptic Damage Markers (Synaptotamin-BDP) Dendritic Damage Markers (MAP2 / CRMP-2) Modified after Mondello et al., 2011
The Proposal Year 1: Gap analysis of current neurotoxicity assessment strategies by multidisciplinary neurotoxicity working group Literature review and, if accessible, review of internal data of multimodal biomarkers in neurotoxicity Assessment of biomarker assays and (commercial) solutions - status of development Preparation of agenda for neurotoxicity workshop and nomination of compounds/models Preparation of white paper
The Proposal, continued Year 2: Experimental study design of neurotoxicity models and biomarker evaluation: modality/biomarkers to be measured in comparison to histology Definition of endpoints