Optimising CNS-targeted neurotensin-peptide-vector conjugates for induction of therapeutic hypothermia – VEC2Brain

Central Nervous System (CNS) diseases are the world’s leading cause of disability. The brain's blood vessels possess unique anatomical and physiological features - collectively known as the blood-brain barrier (BBB) - that substantially limit the delivery of drugs to the nervous tissue. Strategies for CNS drug delivery are essential for improving existing drugs and bringing new drugs to the market. Among these is the development of vector molecules that will enhance the delivery of drugs across the BBB. In the context of a previous project supported by the ANR (VECtoBrain, 2010-2013) the 4 Partners of the present project (VECT-HORUS, a biotech company and 3 academic laboratories from the CNRS, CEA and INSERM) have set up an efficient consortium for the discovery, optimisation and in vivo validation of peptide-vectors (pVectors) that target human receptors involved in receptor mediated transport (RMT). The primary focus was the human low-density lipoprotein receptor (hLDLR). In brief, the Consortium has demonstrated that its lead pVector VH0445: i) is internalized in BBB endothelial cells, ii) allows RMT in vitro of small organic molecules, peptides and antibodies, iii) accumulates efficiently in LDLR-enriched tissues following i.v. administration, iv) increases brain exposure of an organic molecule such as paclitaxel or peptides that modulate easily-assessed physiological responses in live animals such as nociception or body temperature. Medicinal chemistry-based optimization of VH0445 led to the development of novel analogues with higher in vitro binding affinity to the LDLR target receptor, increased stability in blood and increased delivery in vivo to LDLR-enriched tissues. Two patent applications were filed and granted for VH0445 and these derivatives. A new patent is in preparation for a drug candidate.

The general objective of the VEC2Brain project is to build on the grounds of the previous VECtoBrain Consortium to address 2 specific aims: 1) bring a drug candidate generated within the previous VECtoBrain project to preclinical phases of validation; 2) pursue the development of novel vectors more specific of the BBB and CNS.

1) The neuropeptide neurotensin (NT) was conjugated to VH0445. When administered directly into the brain, NT can elicit hypothermia. When administered by intravenous (iv) route, NT is highly unstable in plasma and does not cross the BBB. The Partners have shown that the VH0445-Linker-NT conjugate (VH-NT) elicits rapid (10-15 min) and prolonged (2-3 hours) hypothermia (-3 to -4°C from basal temperature) when administered iv in mice. Mild therapeutic hypothermia (MTH) is widely used in emergency settings for neuroprotection following cardiac arrest, in newborns with hypoxic ischaemic encephalopathy, and clinical trials are ongoing to assess the benefits of MTH in stroke. To this date, MTH is induced only by means of medical devices, but there is still no pharmaceutical alternative. The first objective of the VEC2Brain project is to develop the VH-NT conjugate as an optimal drug candidate validated in preclinical settings within the next 2-3 years.

2) The most acute demand from the pharmaceutical industry interested in brain targeting via RMT is the identification of receptors that are as specific as possible for the BBB and CNS. Indeed all receptors (LRP1, LDLR, Transferrin receptor..) targeted to date by different companies are also expressed in several peripheral organs. The Partners of the VEC2Brain project have identified a receptor of the LDLR family that exhibits better BBB and CNS specificity. A preliminary collection of novel lead pVector are already available that target this receptor in vitro. The second objective of the VEC2Brain project is to evaluate this receptor’s efficacy in RMT in vivo. As a complementary approach, the Consortium will use transcriptomic data and proteomic approaches on endothelial cells and microvessels to identify novel BBB specific receptor targets.