Lentiviral Gene Therapy for Cystic Fibrosis: A Promising Approach and First-in-Human Trial

New ionizable lipids for non-viral mRNA delivery with secondary amine cyclic ether head groups

Lipid nanoparticles (LNPs) are the most widely used non-viral delivery approach for messenger ribonucleic acid (mRNA). Among the different components in an LNP, the ionizable lipid plays critical roles in interacting with the mRNA cargo and facilitating delivery to the cytosol, as well as influencing the LNP's tissue tropism via the protein corona. To date the most successful ionizable lipids have relied on a tertiary amine head group as the site of protonation. We hypothesized that potent ionizable lipids based on a secondary amine could be discovered using a design, make, test and analyze (DMTA) cycle approach. Starting from a lead lipid with a secondary amine cyclic ether head group, we optimized delivery efficiency by systematically modifying the lipid linker length, tail symmetry, tail branching pattern, and head group structure. The mRNA-LNPs formulated with these lipids were evaluated in vivo by quantifying liver protein expression. Using this rational lipid design strategy, we identified many candidates that outperformed the benchmark lipid (MC3), supporting the further development of this ionizable lipid class. Notably, several structure activity relationships (SARs) that highlight how sensitive ionizable lipid activity is to relatively minor structural changes are reported.

Progress of personalized medicine of cystic fibrosis in the times of efficient CFTR modulators

BACKGROUND

Cystic fibrosis (CF) is a systemic disorder of exocrine glands that is caused by mutations in the CFTR gene.

MAIN BODY

The basic defect in people with CF (pwCF) leads to impaired epithelial transport of chloride and bicarbonate that can be assessed by CFTR biomarkers, i.e. the β-adrenergic sweat rate and sweat chloride concentration (SCC), chloride conductance of the nasal respiratory epithelium (NPD), urine secretion of bicarbonate, intestinal current measurements (ICM) of chloride secretory responses in rectal biopsies and in bioassays of chloride transport in organoids or cell cultures. CFTR modulators are a novel class of drugs that improve defective posttranslational processing, trafficking and function of mutant CFTR. By April 2025, triple combination therapy with the CFTR potentiator ivacaftor (IVA) and the CFTR correctors elexacaftor (ELX) and tezacaftor (TEZ) has been approved in Europe for the treatment of all pwCF who do not carry two minimal function CFTR mutations. Previous phase 3 and post-approval phase 4 studies in pwCF who harbour one or two alleles of the major mutation F508del consistently reported significant improvements of lung function and anthropometry upon initiation of ELX/TEZ/IVA compared to baseline. Normalization of SCC, NPD and ICM correlated with clinical outcomes on the population level, but the restoration of CFTR function was diverse and not predictive for clinical outcome in the individual patient. Theratyping of non-F508del CF genotypes in patient-derived organoids and cell cultures revealed for most cases clinically meaningful increases of CFTR activity upon exposure to ELX/TEZ/IVA. Likewise, every second CF patient with non-F508del genotypes improved in SCC and clinical outcome upon exposure to ELX/TEZ/IVA indicating that triple CFTR modulator therapy is potentially beneficial for all pwCF who do not carry two minimal function CFTR mutations. This group who is not eligible for CFTR modulators may opt for gene addition therapy in the future, as the first-in-human trial with a recombinant lentiviral vector is underway.

FUTURE DIRECTIONS

The upcoming generation of pwCF will probably experience a rather normal life in childhood and adolescence. To classify the upcoming personal signatures of CF disease in the times of efficient modulators, we need more sensitive CFTR biomarkers that address the long-term course of airway and gut microbiome, host defense, epithelial homeostasis and multiorgan metabolism.

CFTR function in alveolar type 1 cells drives lung liquid secretion and host defense

Loss of the liquid layer that lines the lung's air-facing surface underpins mechanisms of major lung diseases, but the development of therapies that restore liquid secretion is hampered by an incomplete understanding of the cell types that drive it. Here, we show CFTR function in alveolar type 1 (AT1) cells - a cell type that comprises 95% of the lung surface but is presumed to be unimportant in CFTR-related diseases - is critical to lung liquid secretion and the secretion-mediated clearance of particles and S. aureus from lung alveoli. Our findings reveal essential roles for AT1 cells in lung homeostasis and defense, and they call for a reevaluation of the role of AT1 cells in CFTR-related diseases. We suggest AT1 cells be considered key targets of secretion-restoring therapies.