Discovery of Novel Blood-Brain Barrier Targeting Antibodies for the Treatment of Alzheimer's Disease

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SUMMARY Over 5 million Americans suffer from Alzheimer’s Disease (AD). The approved therapies available for AD only treat symptoms and do not address the underlying neurodegeneration. Importantly, disease-modifying therapeutics (DMT) to delay onset or progression of AD could reduce up to 50% of AD cases. However, the major hurdle to developing DMTs for AD is the largely impermeable blood brain barrier (BBB). 98% of all systemically administered therapeutics and virtually all antibodies fail to reach the brain, and thus are ineffective at treating AD. Members of BBB transporters have been previously used to transport nanoparticle formulations, but are associated with significant scientific complexity and toxicity risk. Abilita Bio will circumvent these risks by using its proprietary and innovative platform, Enabled Membrane ProteinTM (EMP), to develop single domain antibodies (sdAbs) that will latch onto transporters without altering their natural function, enter the BBB via endocytosis, then into the brain via exocytosis. However, expression level of transporters and their efficiency widely vary. Therefore, Abilita Bio will take a multi-target approach to identify a strong candidate. We have identified transporters from 4 different functional subfamilies to test as novel antibody targets to deliver AD therapeutics through the BBB. The goal of this Phase I SBIR proposal is to develop sdAbs of our 4 identified targets and perform proof-of- concept of BBB transport in vitro. This will be accomplished through the execution of 3 aims. In Aim 1, we will use our EMP platform to evolve the 4 targets to generate variants with enhanced properties while maintaining wildtype function. In Aim 2, we will immunize llamas with our EMP variants to develop sdAbs against each target. We will test sdAb hits for specificity and affinity. With our two top hits, we will perform in vitro proof of concept studies using a microfluidic-based BBB model. This model provides more complexity than simple transwell systems and will provide more relevant data to support future in vivo studies. Successful completion of this Phase I program will develop potentially two candidates with in vitro efficacy. This data will inform in vivo efficacy and safety studies in a Phase II program where we will combine our novel BBB transporter sdAb with Abilita Bio’s AD therapeutic that is currently under investigation. Ultimately, the development of this BBB transporter has the potential to improve AD patient outcomes.