Polypharmacology approaches to address disease complexity in cystic fibrosis

Cystic fibrosis (CF) is a life-threatening genetic disease caused by loss-of-function mutations in the CFTR gene, leading to a defective ion channel. This condition chronically affects multiple organ systems, with the lungs and pancreas being the most severely impacted. In the lungs, CFTR mutation results in the accumulation of thick, sticky mucus that clogs the airways, trapping viruses and bacteria. This leads to frequent infections and inflammation, that can ultimately result in serious respiratory issues such as lung damage or respiratory failure. A major advance in CF treatment has been the introduction of CFTR modulators, which have significantly improved symptom management and extended life expectancy for individuals affected by CF. However, additional medications such as antibiotics, inhaled bronchodilators, anti-inflammatory drugs, and pancreatic enzyme supplements are still needed to prevent CF-related complications, control symptoms, and mitigate pulmonary exacerbations. Unfortunately, while these treatments improve health conditions, they also increase the therapeutic burden, bringing a higher risk of side effects, decreased adherence, emotional and psychological stress and increased financial strain. Considering CF complexity and the absence of long-term, sustainable treatment, the main goal of this PhD project has been to address cystic fibrosis by exploiting a polypharmacology approach to develop novel dual-acting compounds that simultaneously target CFTR correction and prevent viral or bacterial infections and inflammation. This approach aims at reducing the CF drug burden, minimizing the risk of drug-drug interactions, lowering treatment costs, streamlining the therapeutic regimen, and improving patient compliance and treatment effectiveness. In the first part of this PhD thesis, the versatility of the bithiazole chemotype was explored to develop dual-acting derivatives in an effort to manage both the genetic defect and infections associated with cystic fibrosis. In particular, the development of antiviral-correctors led to the identification of compound 8b as the best candidate of this class, simultaneously targeting the CFTR channel and the host lipid kinase PI4KB, demonstrating broad-spectrum antiviral activity on different viral families and effective correction of the F508del-CFTR defect. Then, the bithiazole scaffold has been exploited to develop antibacterial-correctors that simultaneously inhibit bacterial growth by targeting bacterial topoisomerases and correct F508del-CFTR, indirectly improving pulmonary microbial clearance. Derivatives 35a and 41a have been identified as the antibacterial-corrector hit compounds belonging to this series. In addition, the development of broad-spectrum antimicrobials resulted in the identification of 49a and 49j as the best candidates. These compounds are designed to combat virus-induced bacterial infections and co-infections in cystic fibrosis, which significantly contribute to disease progression, exacerbations, and higher mortality rates. In the second part of this thesis, the benzofuran-2-carboxamide chemotype was investigated. It has been exploited to develop immunomodulators capable of reducing CCL20-mediated chemotaxis aimed at mitigating inflammation in CF airways. This investigation led to the identification of position C5 on the benzofuran scaffold as the most interesting, especially highlighting compounds 74d and 74f as the best immunomodulatory candidates. Then, efforts have been made for the development of novel multi-target antiviral-immunomodulators by targeting the viral helicase nsp13 and modulating the CCL20-induced chemotaxis, with the goal of controlling viral infections and the subsequent cytokine release as a proof of principle for the future potential application of antiviral-immunomodulators in CF patients.