Background

Cystic fibrosis (CF) is a fatal autosomal recessive genetic disorder resulting from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene [1]. Cystic fibrosis (CF) represents the most common lethal hereditary disorder in individuals of Caucasian descent, with an incidence ranging from 1 in 2000 to 1 in 5000 live births [2]. The disease is characterized by dysfunctional ion transport across epithelial cell membranes due to impaired CFTR channel function [3]. This leads to the accumulation of abnormally viscous mucus secretions that obstruct the lungs and pancreas. The clinical picture consequently encompasses chronic pulmonary infections, pancreatic insufficiency, gastrointestinal manifestations, and other sequelae in multiple organ systems. With conventional management strategies, the median life expectancy for individuals with CF is approximately 40 years [4]. CF arises from mutations affecting the CFTR gene that encodes the CFTR chloride ion channel. Over 2000 pathogenic variants in this gene have been identified to date among individuals with cystic fibrosis. However, a single mutation, a 3 base pair deletion referred to as F508del or Phe508del, accounts for approximately 70% of CF alleles. The fundamental molecular defect underlying CF is insufficient levels of normal CFTR protein expression at the apical membrane of epithelial cells or dysfunction of CFTR chloride channels [5]. This disruption in ion and fluid transport results in reduced hydration of epithelial surfaces and diminished clearance of thickened mucus secretions. While CF follows an autosomal recessive pattern of monogenic inheritance, the clinical phenotype demonstrates considerable variability between patients. This is attributed to the effects of modifier genes and environmental factors on the primary ion transport defect [6]. The historical gold standard for confirming a diagnosis of CF has been quantitative analysis of elevated chloride concentrations in sweat, using established diagnostic cut-offs. However, there is increasing reliance on genetic testing strategies to identify disease-causing CFTR mutations. Traditionally, diagnosis occurs only after clinical manifestations develop, often delaying the initiation of essential treatments and preventive measures [7]. There is a pressing need for earlier and more accessible methodologies to diagnose CF pre-symptomatically in at-risk individuals. This would enable timely therapeutic intervention and potentially improved long-term outcomes. Recent scientific advances in newborn screening, genetic analysis, biochemical assays, and biosensor devices provide promising new approaches to non-invasive and patient-friendly diagnostic modalities [8].

Coupling emerging technologies with expanded population screening could enable CF diagnosis within days after birth, prior to the onset of initial lung pathology or malnutrition. Decentralizing testing from specialized CF centers would further increase accessibility and expedite delivery of care upon diagnosis. In summary, advances in CF diagnostic techniques harbor the potential to enhance early detection, predict outcomes, and guide personalized management based on an individual’s specific disease characteristics [9]. Figure 1 represents that CFTR is synthesized through the following steps: (1) Transcription and splicing in the nucleus; (2) Translation, folding, and glycosylation in the endoplasmic reticulum; (3) Transport through the Golgi apparatus for further modifications; (4) Delivery to the cell surface by vesicles. Mutations in the CFTR gene disrupt one or more steps leading to seven classes of defects: (I) Protein synthesis defects like nonsense mutations; (II) Folding abnormalities; (III) Impaired channel gating; (IV) Conductance defects; (V) Trafficking defects preventing surface expression; (VI) Instability at the membrane; (VII) Reduced mRNA production. These disruptions prevent proper chloride transport through CFTR at the plasma membrane [10].

Fig. 1
figure 1

CFTR biosynthetic pathway [10]

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This review aims to highlight emerging innovations in cystic fibrosis biomarkers and therapeutics that are shifting the diagnostic and treatment paradigm. We focus on novel techniques like genetic sequencing, multi-omics profiling, and electrochemical biosensors that provide unprecedented insights into CF biology to enable personalized care. Advances in CFTR modulator drugs, gene editing, mRNA therapy, and stem cell transplantation also hold promise to modify underlying defects rather than just alleviating downstream manifestations. This review will examine key developments in precision diagnosis and molecularly targeted treatments that are transitioning cystic fibrosis management from palliation to potentially modifying disease course and prognosis.

Emerging methodologies for sweat chloride analysis

Quantitative analysis of sweat chloride levels remains the gold standard for confirming a CF diagnosis, with concentrations exceeding 60 mmol/L considered diagnostic. Newer techniques are streamlining and improving the feasibility of this approach, even in infants and young children. The Macroduct® sweat collection system enables easier stimulation and gathering of adequate sweat volumes for analysis in children as young as 2 weeks of age [11]. Studies have found the Macroduct System to be comparable in accuracy to the classic Gibson-Cooke filter paper technique [12]. The Nanoduct® device reduces the required duration of sweat collection by directly absorbing sweat into a capillary tube. Portable sweat chloride analyzers allow rapid point-of-care testing [13]. A wearable chloride ion sensor using screen printing and heat transfer techniques to print the sensor onto textiles has been developed [14]. Recent advances in technologies for sweat collection and transport include using absorbent pads, arm bags, gloves, and microfluidics [15]. These emerging techniques support expanded newborn and early childhood CF screening initiatives as well as opportunities for earlier diagnosis [16].

Evolution of genetic screening approaches

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CFTR gene. The development of genetic screening approaches for CF has evolved significantly in recent years. Molecular genetic testing is playing an increasingly important role in both targeted and population-based screening approaches for CF, as well as diagnostic confirmation. Genetic panels that detect common CFTR mutations associated with disease risk allow the identification of couples with higher probability of conceiving an affected child. Expanded panels analyzing 97–176 mutations enable detection of over 90% of carriers, improving detection rates especially among individuals of non-European ancestry compared to older tests. For couples deemed high-risk, prenatal or preimplantation genetic diagnosis can directly interrogate fetal/embryonic CF status to facilitate family planning and reproductive decisions [17]. Furthermore, next-generation sequencing methodologies now provide a comprehensive approach to identify rare, private CFTR mutations missed by standard mutation panel screening. While currently more expensive, whole exome or genome sequencing may eventually become a viable single-step methodology for both familial carrier screening as well as diagnostic testing after birth. It also promises to illuminate novel CF disease alleles. Integrating expanded NGS-based genetic screening and sequencing strategies could enhance the diagnosis of CF, particularly in newborns with inconclusive or borderline sweat chloride results. As costs decrease and accuracy improves, comprehensive CFTR genetic testing is poised to enable personalized risk assessment, family planning, and therapeutic decision-making [18].

Originally, screening focused on detecting a limited number of common CFTR mutations, such as F508del, in certain high-risk populations like Ashkenazi Jews and Northern Europeans. However, with advances in DNA sequencing technology and decreased costs, comprehensive CFTR gene sequencing is now feasible and recommended. In 2001, professional guidelines recommended screening for a panel of 23 CFTR mutations that accounted for over 70% of CF carriers [19]. In 2022, new guidelines were released recommending screening for a minimum of 100 CFTR variants to improve detection rates across diverse populations [20]. The expanded panel was based on curated databases like CFTR2 and aimed to identify at least 95% of carriers across major ancestral groups [21]. The transition to expanded, sequencing-based screening improves equity by removing reliance on self-reported ethnicity and enables the detection of a wider range of CFTR mutations across all individuals [22]. This evolution to expanded gene sequencing reduces reliance on ethnicity, improves detection of rare alleles, and enables more equitable identification of carriers across all individuals being screened [23].

Electrochemical biosensors for cystic fibrosis diagnosis

Electrochemical biosensor devices represent an emerging approach for detecting and quantifying biochemical changes in the sweat of CF patients. These sensors harness electrode-based chemical reactions to generate electrical signals proportional to the concentration of a sweat analyte. For instance, sensors directly measuring chloride concentrations in CF sweat have been incorporated into skin patches and sweat collection tubes. Other electrochemical biosensors can assess changes in sweat lactate, glucose, pH, or conductivity that typically manifest in CF due to defective reabsorption of these solutes. Miniaturized sensors integrated into microfluidic platforms allow rapid analysis of microliter sweat volumes collected non-invasively. Sensor arrays with multiple electrodes enable simultaneous assessment of multiple sweat analytes potentially indicative of CF pathology. Compared to traditional biochemical assays, electrochemical sensing provides simple, inexpensive, and painless measurement of sweat composition in real-time without extensive sample processing. When combined with wearable devices for sweat stimulation and collection, on-body electrochemical sensor systems could enable rapid, point-of-care CF screening and diagnosis. With further optimization of sensor specificity, selectivity, and integration into user-friendly devices, sweat analysis with electrochemical biosensors holds strong potential for accessible, non-invasive evaluation of CF disease status [24].

Recent research has focused on developing electrochemical biosensors as an alternative diagnostic approach for CF. Electrochemical biosensors incorporate biological recognition elements, such as enzymes, directly onto the sensor surface. This allows rapid, sensitive detection of target biomarkers through electrochemical signals. Ion-sensitive field effect transistors (ISFETs) are a promising type of electrochemical biosensor for detecting chloride ion levels in sweat for CF diagnosis [25]. In ISFETs, chloride ions directly interact with the hydroxyl groups on the gate oxide surface, displacing protons and altering the transistor’s output signal. Detailed modeling of the ISFET sensor using finite element methods has been critical to optimizing the sensor design [26]. Simulations modeling the chemical reactions at the interface between the gate oxide and sweat electrolyte solution have guided improvements in ISFET sensitivity. Recent designs using hafnium oxide as the gate insulator material demonstrate detection limits around 0.004 mol/m3 for sweat chloride. ISFET biosensors offer an ideal diagnostic alternative to traditional sweat testing for CF. As a non-invasive, rapid, low-cost, and easy-to-use technology, ISFETs allow real-time, continuous monitoring of sweat chloride levels [27]. This can enable earlier diagnosis of CF in patients and improved tracking of disease status and treatment effectiveness over time. Further optimization of parameters such as stability, selectivity, and reproducibility is still needed to fully translate ISFET biosensors to clinical CF diagnostic applications. However, recent research on their design and performance represents important progress towards replacing cumbersome sweat tests with real-time, point-of-care CF diagnosis using electrochemical biosensors [28].

Novel molecular biomarkers for cystic fibrosis diagnosis and prognosis

Cystic fibrosis is an autosomal recessive disorder stemming from diverse mutations in the CFTR gene that disrupt protein production and chloride channel function, leading to multiorgan disease phenotypes. While diagnosis has traditionally relied on clinical presentation and sweat chloride testing, an array of novel molecular biomarkers are providing new avenues to understand the genomic, transcriptomic, proteomic, metabolomic, and microbiomic underpinnings of disease in individual patients [29,30,31]. These innovative technologies enable analysis of the diverse molecular components influenced by CF pathology, delivering a more comprehensive platform to inform personalized management. Recent research has identified promising molecular biomarkers to improve diagnosis and prognosis in cystic fibrosis (CF). Sivagurunathan and Al Basheer (2022) review monoclonal antibodies as emerging diagnostic biomarkers, since they can specifically target mutated CFTR proteins [32]. Tang et al. (2022) discuss using network biomarkers to analyze complex molecular interactions and pathways in rare diseases like CF [33].

Finally, Tomos et al. (2023) highlight genetic biomarkers associated with disease severity and progression in idiopathic pulmonary fibrosis, a common CF comorbidity. Overall, molecular biomarkers like mutated proteins, antibody targets, genetic markers, and networked pathway analyses offer new approaches to enhance early CF detection, predict patient outcomes, and inform treatment decisions through precise, personalized medicine [34]. Figure 2 represents that pulmonary fibrosis (PF) arises from interactions between risk factors, epithelial cells, mesenchymal cells, and extracellular matrix (ECM). Injured alveolar epithelium secretes cytokines like TGF-β, causing fibroblasts to differentiate into contractile myofibroblasts that produce ECM. Activated myofibroblasts also release inflammatory mediators like TGF-β, IL-1, and IL-33, further promoting fibrosis and inflammation. The accumulated ECM acts as a reservoir of mediators, creating a positive feedback loop driving continued myofibroblast activation and ECM production. Myofibroblast and ECM buildup increases tissue stiffness and mechanical tension, resulting in more fibrotic remodeling [35].

Fig. 2
figure 2

Pathogenesis of pulmonary fibrosis [35]

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Immunoassays for direct quantification of CFTR protein

The fundamental molecular defect in CF is insufficient expression of normal CFTR protein at the apical membrane or dysfunction of CFTR chloride channels caused by mutations [36]. Enhanced regulatory T cell percentages in adults receiving elexacaftor/tezacaftor/ivacaftor using flow cytometry. Microbiota and inflammation changes linked to Pseudomonas aeruginosa infection status in patients receiving lumacaftor-ivacaftor using multiplex immunoassays [37]. Nonsense mutation suppression therapy with nonsense-mediated decay inhibition to restore CFTR protein expression in cells from neurofibromatosis patients using ELISA. Immunoassays utilizing CFTR-specific antibodies can directly quantify CFTR abundance and assess channel activity. For immunostaining approaches, epithelial cells can be obtained from rectal biopsies or nasal brushing for ex vivo analyses. Monoclonal antibodies recognizing extracellular epitopes are applied, followed by fluorophore-conjugated secondary antibodies to visualize and quantify CFTR localization and expression levels. These assays provide definitive evidence of abnormal CFTR trafficking or function at the protein level [38]. Measuring dynamic changes in CFTR protein over time may also help monitor response to novel therapies aimed at increasing CFTR production through correctors or amplifiers. In addition to microscopic imaging, high-throughput functional assays have been developed to directly measure CFTR activity. The Halide-Sensitive YFP fluorescent assay uses a halide-sensing yellow fluorescent protein to dynamically track CFTR-mediated iodide influx as a surrogate for chloride transport. This allows rapid in vitro screening of CFTR channel function in response to modulator drugs. More complex assays like the Ussing chamber technique directly assess transepithelial ion transport in dissected tissues or cultured epithelia. Combined with pharmacological inhibitors, Ussing chamber experiments can isolate CFTR-dependent anion secretion. These functional tools will be invaluable for assessing CFTR activity to guide diagnosis and treatment decisions, especially for rare mutations with unknown consequences [39].

Analyzing mRNA transcripts for insights into mutations

While CFTR mutation analysis is currently used to confirm clinical diagnosis and broadly predict disease severity, it provides limited information about the effects of specific mutations on processes like RNA transcription, splicing, and protein synthesis. Direct analysis of mRNA transcripts offers deeper insight into the functional consequences of genetic variants on these intermediate molecular steps linking genotype to phenotype. mRNA can be extracted from nasal epithelial cells or rectal biopsies for RNA sequencing, mapping aberrant splicing patterns, and quantifying normal versus anomalously spliced CFTR transcripts [40]. This approach has uncovered abnormal mRNA splicing in approximately 15% of CF alleles, including splice site mutations, exon skipping events, and usage of cryptic splice sites. For instance, the 3849 + 10kbC → T mutation generates a novel upstream splice donor site that erroneously incorporates a 10-kb intronic sequence. Many such splicing defects introduce premature termination codons (PTCs) leading to nonsense-mediated decay and reduced CFTR production [41]. Beyond mRNA splicing analysis, RNA sequencing is a powerful tool to screen for nonsense and frameshift mutations introducing PTCs that are difficult to identify by genomic analysis alone. The introduction of PTCs which truncate the protein is a strong predictor of disease severity. RNA analysis also enables quantitative measurement of overall CFTR mRNA expression levels, which may be reduced by mutations affecting transcription or message stability. Therefore, interrogating mRNA provides multilayered insights into the diverse ways CFTR mutations can disrupt gene processing to compromise protein abundance and function. In an era of mutation-specific therapeutic approaches, these molecular details will be essential for selecting targeted treatments and anticipating clinical response [42].

Multi-omics approaches for holistic disease profiling

While genomic and transcriptomic analyses can predict downstream effects of CFTR dysfunction, directly measuring proteomic, metabolomic, and microbiomic changes provides invaluable information about actual disease manifestations in each patient. These unbiased multi-omics approaches analyze global changes across the genome, proteome, metabolome, and microbiome that reflect the intricate molecular networks underlying CF pathology [43, 44]. Integrating such multidimensional datasets enhances prognostic abilities and enables more customized therapy based on an individual’s unique omics profile [45].

Proteomics examines broad changes in protein content, interactions, structure, and function on a systems-wide level. Compared to non-CF cells, the CF airway epithelium exhibits altered expression of proteins related to host defense, inflammation, redox homeostasis, and protein quality control. Intriguingly, proteomic differences also emerge between CF patients with mild versus severe clinical phenotypes and genotypes. Those with milder disease demonstrate upregulation of proteins regulating antioxidant pathways, protein homeostasis, and lung protection. By contrast, those with more severe CF phenotypes have increased expression of pro-inflammatory proteins but decreased levels of protective factors like antimicrobial peptides. These molecular patterns likely contribute to progressive lung function decline. Therefore, proteomic biomarkers in epithelial cells could help predict disease course and guide the intensity of therapeutic interventions [46].

Metabolomics assesses global perturbations in the complete set of small molecule metabolites that are influenced by cellular pathways and enzymatic reactions. CF disrupts metabolic homeostasis, and unbiased metabolite screening could uncover patient subgroups and opportunities for personalized therapy. For instance, mass spectrometry-based plasma metabolite profiling can accurately distinguish CF patients from healthy individuals. Hallmarks of CF metabolism include altered energy metabolism, amino acid pools, oxidative stress markers, and fatty acid levels. Urine and airway fluid also demonstrate metabolic derangements that correlate with disease severity. Longitudinal sampling may eventually enable early detection of shifting metabolites that portend pulmonary exacerbations. Lastly, microbial community dysbiosis contributes significantly to CF lung pathology, while cultures remain useful for identifying pathogenic bacteria like Pseudomonas aeruginosa, culture-independent [47, 48].

Microbiome profiling by sequencing allows high-resolution characterization of overall airway bacterial community structure. Compared to healthy airways, CF lungs harbor decreased microbial diversity and are dominated by a few pathogenic species like Pseudomonas and Staphylococcus. Intriguingly, the airway microbiome composition fluctuates dynamically during pulmonary exacerbations and antibiotic therapy. Furthermore, oropharyngeal microbiome patterns correlate with CF phenotype severity. Integrating airway microbiome data with clinical metadata may therefore help predict and manage respiratory exacerbations through monitoring of microbial community structure [49].

Transcriptomic profiling of patient samples can provide insights into disease mechanisms. For single-cell RNA sequencing (scRNA-seq), cells from samples like blood or tissue are isolated and dissociated into single cells. After antibody labeling to sort cell types, reverse transcription and cDNA amplification are performed before high-throughput sequencing. This allows the characterization of distinct cell populations, receptors, and pathways. For spatial transcriptomics, tissue sections are prepared and exposed to probes that target specific RNA sequences. After ligation, amplification, and tagging, the location of transcript expression can be visualized. While scRNA-seq provides cell-specific data from dissociated cells, spatial techniques map transcripts while preserving anatomical context. Together, these methods link transcriptional profiles to specific cells and locations within patient samples. This has identified novel cell states, transitions, and rare populations involved in diseases like cystic fibrosis. Computational analysis of scRNA-seq data has also revealed new cell phenotypes in infections, like a monocyte subtype linked to sepsis [50, 51].

Challenges to clinical translation of novel CF biomarkers

The emergence of advanced diagnostic biomarkers has opened exciting new windows into the intricate molecular landscape of cystic fibrosis. Next-generation sequencing enables in-depth interrogation of the CFTR gene and mutations. Meanwhile, multi-omics platforms profile downstream proteomic, metabolomic, and microbiomic perturbations providing a comprehensive perspective on CF biology with unprecedented granularity [52]. Large-scale validation studies enrolling patients spanning the spectrum of CF genotypes, ages, and disease severities are needed to establish these performance characteristics. Head-to-head comparisons against current gold standard diagnostic methods will help determine if new tests offer improved accuracy. In addition to intrinsic test performance, potential sources of interference must be rigorously evaluated. Factors in the testing process or patient characteristics that could generate false positive or negative results should be identified. For example, the presence of non-CF conditions with elevated sweat chloride or variants in non-CFTR genes could potentially confound test interpretation. However, substantial barriers must still be overcome prior to widespread clinical adoption of these novel CF biomarkers. Demonstrating validity in real-world diverse populations, securing insurance coverage, and streamlining integration into clinical workflows represent significant challenges necessitating further investment and research [53].

Demonstrating clinical validity and utility

Robust validation in heterogeneous real-world cystic fibrosis (CF) populations is essential before adopting novel CF biomarkers in clinical practice. Assay accuracy requires assessment across diverse CF genotypes and age groups. Beyond intrinsic validation, clinical utility studies via randomized trials are critical to demonstrate sufficient improvements in outcomes versus standard diagnostic algorithms to justify economic costs. Incremental benefits over inexpensive confirmatory sweat testing need clarification. Scenarios warranting more expensive multi-omic testing require definition, whether for inconclusive sweat testing or therapy selection. Comparative-effectiveness trials randomizing patients to care guided by standard techniques or innovative biomarkers represent the highest level of evidence to establish utility. By comparing outcomes and cost-effectiveness between study arms, such trials can provide compelling evidence of real-world value over current best practices [54].

Cost-effectiveness and insurance coverage considerations

The high costs of platforms like next-generation sequencing and mass spectrometry-based omics profiling pose another major adoption barrier. Widespread implementation requires that payers judge the clinical benefits as commensurate with added expenses and therefore provide coverage for novel biomarkers. This entails formal cost-effectiveness analyses which are currently lacking for most new CF diagnostic modalities. Incremental cost-effectiveness ratios quantify the additional expenditures needed to gain specific health improvements like added life-years when applying biomarkers to guide care [55].

Integrating biomarkers into diagnostic workflows

Deploying novel CF biomarkers in real-world settings faces practical barriers like specialized equipment, advanced analytics, and bioinformatics expertise typically restricted to research laboratories. Seamless integration requires substantial investment in computational infrastructure and streamlined diagnostic pipelines, representing a major overhaul of protocols optimized for standard tests. Point-of-care devices could enable decentralization but require quality assurance programs for proper technique and interpretation by newly trained staff. Most innovative techniques lack FDA oversight as laboratory-developed tests, enabling rapid innovation but uncertainty around evidentiary standards. Partnerships with diagnostic manufacturers can facilitate FDA approval to enhance quality standards, albeit with increased costs and timelines [56, 57].

Future outlook

Despite current barriers, CF biomarkers hold tremendous potential to transform clinical care as technology and evidence evolve. One active area is developing integrated point-of-care platforms that combine different modalities to provide rapid sample-to-answer testing [58]. For instance, microfluidic devices could perform simultaneous genetic analysis and sweat chloride quantification from minute volumes. Such technologies deployed at the point-of-care could overcome logistical constraints. Wearable biosensors also have the potential for continuous monitoring of CF-relevant biomarkers [59]. Miniaturized home devices could track metrics like sweat electrolytes, lung function, or metabolites to identify early changes signaling impending exacerbations. However, remote testing still requires oversight infrastructure to ensure proper quality control and result interpretation. Hybrid telehealth systems could help connect local providers and patients to specialty CF hubs that provide guidance and oversight over decentralized testing [60]. Looking ahead, newborn screening and pre-symptomatic diagnosis could fundamentally revolutionize CF outcomes by enabling very early intervention to prevent organ damage. New, inexpensive automated techniques suitable for population screening programs may eventually make this a reality. Overcoming the barriers outlined here will be critical to unlocking the full benefits of emerging biomarkers and ushering in a new era of precision prevention, screening, and management for cystic fibrosis [61].

Therapeutic advances targeting cystic fibrosis pathogenesis

While cystic fibrosis remains incurable, recent therapeutic advances are shifting the treatment paradigm towards targeting the molecular defects underlying CF pathology. This approach aims to modify the disease course rather than merely addressing downstream manifestations [62]. The mainstay of conventional CF care has included airway clearance techniques, antibiotics, pancreatic enzyme replacement, and nutritional support. However, novel agents that rescue mutant CFTR protein expression or function have now entered clinical practice. Gene editing, mRNA-based, and stem cell therapies also show promise for restoring normal CFTR biology. Fibrosis is a major health concern, but disease mechanisms are still not fully understood. Developing antifibrotic therapies requires comprehending organ-specific profibrotic processes [63]. Due to heterogeneity in causes, phenotypes, and lack of validated biomarkers, there are no effective disease-modifying antifibrotics. Current approaches rely on compounds that inhibit fibrosis-related pathways like TGF-β (Fig. 3A). Other strategies are being explored including the following: inhibiting RAS (Fig. 3B); biomaterial-based delivery (Fig. 3C); mesenchymal stem cell therapy (Fig. 3D); engineered CAR T cell therapy (Fig. 3E); and gene therapy mediating miRNA (Fig. 3F). As fibrosis pathology varies across organs, emerging therapies aim to target processes specific to each tissue context [64].

Fig. 3
figure 3

Emerging antifibrotic therapies [64]

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CFTR modulator drugs

The advent of CFTR modulators that correct specific molecular defects has transformed outcomes for many patients. The first drug approved was ivacaftor, a potentiator that augments channel gating and open probability, providing substantial benefits for patients with gating mutations like G551D [65]. However, such mutations are responsible for under 5% of cases. A major goal became developing corrector compounds to improve cellular processing and trafficking of F508del mutated CFTR protein, the most prevalent disease allele. The corrector lumacaftor was approved in combination with ivacaftor in 2015, conferring modest improvements in lung function and exacerbation rates for homozygous F508del patients. But lumacaftor alone only partially rescues cellular expression and function of F508del CFTR [66]. This led to the development of triple combination regimens demonstrating enhanced clinical efficacy by synergistically targeting multiple molecular defects. The vertex triple therapy comprising correctors tezacaftor and elexacaftor plus ivacaftor was approved in 2019 after dramatically improving FEV1 and reducing exacerbations. An alternative triple therapy from AbbVie showed similar benefits [67]. These combinations increase the fraction of individuals with CF who may benefit from modulator therapy to over 90%. However, challenges remain in extending efficacy to less common mutations and patients with minimal residual CFTR function. Future directions include developing mutation-specific correctors, optimizing drug delivery, and exploring agents that promote the degradation of misfolded CFTR [68].

Gene and mRNA therapies

Gene editing strategies using CRISPR/Cas9 to directly repair CFTR mutations in airway stem cells also show promising curative potential based on preclinical studies, but efficient in vivo editing remains challenging. Clinical trials are planned to assess the feasibility of delivering corrected autologous stem cell-derived epithelial cells to CF patients’ airways [69]. In addition to gene-edited organoids, mRNA-based augmentation of CFTR expression is also under study. Nebulized mRNA could provide temporary vector-free CFTR supplementation to potentially stabilize or prevent acute pulmonary exacerbations. Both gene editing and mRNA therapy aim to address the root genetic cause of CF pathology [70].

Stem cell approaches

Stem cell models of CF aid drug development and provide regenerative medicine options. Gene-edited intestinal organoids and airway epithelium derived from induced pluripotent stem cells demonstrate restored ion transport upon CFTR repair [71]. Transplantation of such autologous stem cell-derived tissues is being explored to permanently replace CFTR-deficient cells [72]. Separately, mesenchymal stem cell (MSC) transplantation is also under study for modulating inflammation and infection. MSCs release beneficial paracrine factors and may confer epithelial protection. Early trials indicate acceptable safety of intravenous MSC infusions in CF patients [73].

Conclusions

In summary, directly targeting the molecular defects underlying cystic fibrosis pathology represents a paradigm shift in disease management. Small molecule CFTR modulators, gene editing, mRNA therapy, and stem cell-based approaches aim to restore normal CFTR expression and function, potentially modifying the natural history of CF lung disease. While these strategies offer hope for improved outcomes, significant challenges remain before widespread clinical adoption. High costs pose barriers to access, and long-term safety and efficacy across diverse patient subgroups require further study. Additionally, complementary symptomatic treatments remain essential, as even highly effective CFTR modulators cannot reverse pre-existing organ damage. Despite these limitations, emerging molecularly targeted therapeutics hold immense promise to transform the prognosis for individuals with CF from a fatal childhood disease to a chronic condition with improved quality of life and survival.

Recommendations

To realize the full potential of precision CF therapies, robust validation studies in real-world patient populations are critical. Head-to-head comparisons against standard diagnostic algorithms and treatments through randomized clinical trials will help establish the incremental benefits of novel biomarker-guided approaches. Innovative delivery platforms like wearable biosensors and point-of-care microfluidic devices should be optimized to decentralize testing and enable remote monitoring. Lastly, further investment in elucidating CFTR biology and characterizing rare variants is essential to expand therapeutic options for all patients, regardless of genotype. Overcoming current limitations will require multidisciplinary collaborations between researchers, clinicians, patients, and industry partners to accelerate the translation of groundbreaking discoveries into transformative therapies accessible to the entire CF community.