Developing inhaled drugs for respiratory diseases: A medicinal chemistry perspective

Despite the devastating impact of many lung diseases on human health, there is still a significant unmet medical need in respiratory diseases, for which inhaled delivery represents a crucial strategy. More guidance on how to design and carry out multidisciplinary inhaled projects is needed. When designing inhaled drugs, the medicinal chemist must carefully balance the physicochemical properties of the molecule to achieve optimal target engagement in the lung. Although the medicinal chemistry strategy is unique for each project, and will change depending on multiple factors, such as the disease, target, systemic risk, delivery device, and formulation, general guidelines aiding inhaled drug design can be applied and are summarised in this review.

Abstract 4457: Open science medicinal chemistry: Towards a treatment for DIPG

Meds4Kids Pharma (M4K)1 is pioneering an open science approach to drug discovery, focussed on the discovery and development of small molecule therapeutics for orphan paediatric cancers. M4K seeks to test the hypothesis that an open science framework can be successfully applied not only to accelerate basic science, using the collective knowledge of the scientific community at large, but also to take an innovative new drug candidate all the way from discovery and clinical proof-of-concept through to product registration, by making use of regulatory data protections and market incentives. Since late 2017, Charles River Early Discovery has been providing in kind drug discovery services to help progress these efforts, including medicinal and synthetic chemistry. The first M4K project aims to generate an orally-available, brain-penetrant therapeutic to treat the diffuse intrinsic pontine glioma (DIPG). DIPG is a rare, aggressive and uniformly fatal childhood brain cancer with a median survival time of 9-12 months and for which there are currently no effective drug treatments. The disease has been shown to be associated with mutations in the ACVR1 gene (activin A receptor, type 1) also known as ALK2 kinase. Early support for the therapeutic hypothesis that an inhibitor of ALK2 kinase would have clinical benefit in DIPG, came from in vivo studies with non-selective ALK2 kinase inhibitors, which both killed DIPG cell lines harbouring the ALK2 mutation and extended lifespan in xenograft mouse models.2 Working collaboratively with M4K and their open science partners, we have made excellent progress towards the identification of potent, selective, brain penetrant ALK2 inhibitors starting from the known inhibitor LDN-214117, previously described for FOP (fibrodysplasia ossificans progressiva).3 Our current lead compound has an excellent in vitro and in vivo profile showing high oral bioavailability and brain penetration in a mouse PK study and is progressing to proof of concept studies. In addition we are progressing with the identification of a back-up series. References: 1. https://m4kpharma.com/ 2. Carvalho et. al. Neuro-Oncology, Volume 18, Issue suppl_6, 1 November 2016, Pages vi154, https://doi.org/10.1093/neuonc/now212.639 3. Mohedas et. al., J. Med Chem, 2014, 57 (19), 7900

Citation Format: Sue Cramp, Nicole Hamblin, Jeff O'Meara, Aled Edwards, Owen Roberts, Alex Bullock, Paul Brennan. Open science medicinal chemistry: Towards a treatment for DIPG [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4457.

Targeting phosphoinositide 3-kinase δ for the treatment of respiratory diseases

Asthma and chronic obstructive pulmonary disease (COPD) are characterized in their pathogenesis by chronic inflammation in the airways. Phosphoinositide 3-kinase δ (PI3Kδ), a lipid kinase expressed predominantly in leukocytes, is thought to hold much promise as a therapeutic target for such inflammatory conditions. Of particular interest for the treatment of severe respiratory disease is the observation that inhibition of PI3Kδ may restore steroid effectiveness under conditions of oxidative stress. PI3Kδ inhibition may also prevent recruitment of inflammatory cells, including T lymphocytes and neutrophils, as well as the release of proinflammatory mediators, such as cytokines, chemokines, reactive oxygen species, and proteolytic enzymes. In addition, targeting the PI3Kδ pathway could reduce the incidence of pathogen-induced exacerbations by improving macrophage-mediated bacterial clearance. In this review, we discuss the potential and highlight the unknowns of targeting PI3Kδ for the treatment of respiratory disease, focusing on recent developments in the role of the PI3Kδ pathway in inflammatory cell types believed to be critical to the pathogenesis of COPD.