Cystic Fibrosis Transmembrane Conductance Regulator Research Articles

Impact of Cystic Fibrosis Transmembrane Conductance Regulator Modulators on Maternal Outcomes During and After Pregnancy

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulators are available to the majority of people with CF in the United States; little is known about pregnancy outcomes with modulator use. The aim of this retrospective study was to determine the impact of CFTR modulators on maternal outcomes. Does pregnancy differentially affect outcomes in female subjects with CF with and without CFTR modulator exposure? Data on pregnancies from 2010 to 2021 were collected from 11 US adult CF centers. Multivariable longitudinal regression analysis was performed to assess whether changes in percent predicted FEV1 (ppFEV1), BMI, pulmonary exacerbations (PEx), and Pseudomonas aeruginosa prevalence differed from prior to, during, and following pregnancy according to CFTR modulator use while adjusting for confounders. Infant outcomes are also described based on maternal modulator use. Among 307 pregnancies, mean age at conception was 28.5 years (range, 17-42 years), prepregnancy ppFEV1 was 74.2, and BMI was 22.3kg/m2. A total of 114 pregnancies (37.1%) had CFTR modulator exposure during pregnancy (77 with highly effective modulator therapy [HEMT] and 37 with other modulators). The adjusted mean change in ppFEV1 from prepregnancy to during pregnancy was -2.36 (95%CI, -3.56 to -1.16) in the unexposed group and 2.60 (95%CI, 0.23 to 4.97) in the HEMT group, with no significant change from during pregnancy to 1 year postpregnancy. There was an overall decline in ppFEV1 from prepregnancy to postpregnancy in the no modulator group (-2.56; 95%CI, -3.62 to -1.49) that was not observed in the HEMT group (1.10; 95%CI, -1.13 to 3.34). PEx decreased from prepregnancy to postpregnancy in the HEMT group, and BMI increased from prepregnancy to during pregnancy in all groups but with no significant change postpregnancy. Missing infant outcomes data precluded firm conclusions. We observed superior pregnancy and postpregnancy pulmonary outcomes in individuals who used HEMT, including a preservation of ppFEV1, compared with those unexposed to HEMT.

Specific kinesin and dynein molecules participate in the unconventional protein secretion of transmembrane proteins.

Secretory proteins, including plasma membrane proteins, are generally known to be transported to the plasma membrane through the endoplasmic reticulum- to-Golgi pathway. However, recent studies have revealed that several plasma membrane proteins and cytosolic proteins lacking a signal peptide are released via an unconventional protein secretion (UcPS) route, bypassing the Golgi during their journey to the cell surface. For instance, transmembrane proteins such as the misfolded cystic fibrosis transmembrane conductance regulator (CFTR) protein and the Spike protein of coronaviruses have been observed to reach the cell surface through a UcPS pathway under cell stress conditions. Nevertheless, the precise mechanisms of the UcPS pathway, particularly the molecular machineries involving cytosolic motor proteins, remain largely unknown. In this study, we identified specific kinesins, namely KIF1A and KIF5A, along with cytoplasmic dynein, as critical players in the unconventional trafficking of CFTR and the SARS-CoV-2 Spike protein. Gene silencing results demonstrated that knockdown of KIF1A, KIF5A, and the KIF-associated adaptor protein SKIP, FYCO1 significantly reduced the UcPS of △F508-CFTR. Moreover, gene silencing of these motor proteins impeded the UcPS of the SARS-CoV-2 Spike protein. However, the same gene silencing did not affect the conventional Golgimediated cell surface trafficking of wild-type CFTR and Spike protein. These findings suggest that specific motor proteins, distinct from those involved in conventional trafficking, are implicated in the stress-induced UcPS of transmembrane proteins.

Update on the Role of Chest Imaging in Cystic Fibrosis.

Cystic fibrosis is a genetic disease with multisystem involvement and associated morbidity and mortality that are most directly related to progressive lung disease. The hallmark findings of cystic fibrosis in the lungs are chronic inflammation and infection, leading to progressive loss of pulmonary function and often requiring lung transplant. Predominant lung findings include mucous plugging, bronchiectasis, and air trapping, often with associated atelectasis, consolidation, and emphysema; these findings form the basis of several clinical scoring systems that are used for imaging assessment. Recently, there have been major breakthroughs in the pharmacologic management of cystic fibrosis, including highly effective modulator therapies that directly target the underlying cystic fibrosis transmembrane conductance regulator molecular defect, often leading to remarkable improvements in lung function and quality of life with corresponding significant improvements in imaging markers. The authors review current guidelines regarding cystic fibrosis with respect to disease monitoring, identifying complications, and managing advanced lung disease. In addition, they discuss the evolving role of imaging, including current trends, emerging technologies, and proposed updates to imaging guidelines endorsed by international expert committees on cystic fibrosis, which favor increased use of cross-sectional imaging to enable earlier detection of structural changes in early disease and more sensitive detection of acute changes in advanced disease. It is important for radiologists to be familiar with these trends and updates so that they can most effectively assist clinicians in guiding the management of patients with cystic fibrosis in all stages of disease. ©RSNA, 2024.

Cystic fibrosis foundation position paper: Redefining the cystic fibrosis care team.

Interdisciplinary teams care for people with cystic fibrosis (pwCF) at specialized treatment centers. These teams have laid the foundation for the cystic fibrosis (CF) care model responsible for gains in health outcomes and quality of life within the CF community. However, the landscape of CF care is transforming, invigorated by new technologies, accessibility of cystic fibrosis transmembrane conductance regulator (CFTR) therapies, and increased utilization of telemedicine. In light of these advances, it is appropriate to re-evaluate the CF care team structure. This position paper offers guidance for the structure of a CF care center designed to meet the evolving needs of the CF community. Fundamental to the proposed center structure is recognition of pwCF and their families as integral members of their care teams, underpinning the necessity for shared decision making, awareness of social determinants of health, and active partnership between all healthcare professionals involved in the care of pwCF.

Dépistage de variant du gène CFTR chez les candidats au don de gamètes en France : quand ? Comment ? Pourquoi ?

ObjectivesAccording to French recommendations, only the caryotype is carried out as a first line in candidates for gamete donation. The prescription of additional genetic tests for variants responsible for serious monogenic diseases is only recommended in the case of call points. However, cystic fibrosis remains the most common genetic disease with serious consequences in childhood. The purpose is to assess the different screening strategies in the Centres d’Études et de Conservation des Œufs et du Sperme humain (CECOS) regarding abnormalities of the Cystic Fibrosis Transmembrane conductance Regulator gene (CFTR). MethodOur study is based on the analysis of data collected using a questionnaire. Private centres authorised to donate have been excluded from this work. ResultsTwenty-six centres participated out of the 33 interviewees. Two centres carry out systematic screening in all their sperm donation candidates while only one centre practises it in its oocyte donation candidates. For the other 23 centres, research is carried out in case of strong clinical suspicions according to personal or family history and when one of the two members of the recipient couple has a known variant. Regarding the molecular analysis technique used, 56.5% of centres use PCR with commercial kits, whereas the other centers use next-generation sequencing. ConclusionTargeted screening therefore remains widely practiced in France unlike other countries. Moving to expanded systematic screening raises ethical, financial and organisational issues.

Cardiac Structure and Function in People with Cystic Fibrosis

BackgroundThe extent of cardiac involvement in cystic fibrosis (CF) remains to be determined. The remarkable therapeutic advancements with new highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator treatment and subsequent increase in life expectancy substantiates further research. We aimed to explore the prevalence of cardiac alterations in people with CF (pwCF) compared to matched controls and investigate potential cardiovascular risk factors. MethodsIn this cross-sectional study, 104 pwCF underwent clinical and echocardiographic assessment. All participants were matched 1:1 with controls from the general population. ResultsOf 104 pwCF, 44 % were female, mean age was 34 years, and 93 % received CFTR modulator treatment. The prevalence of abnormal cardiac function in pwCF was 44 %, more than double the prevalence in controls. PwCF were found to have smaller left ventricular (LV) dimensions, worse LV diastolic function, and reduced right ventricle (RV) as well as LV systolic function. After multivariable adjustment, LV diastolic function as well as LV and RV systolic function remained poorer in pwCF as compared to controls. Male sex and decreasing FEV1/FVC ratio remained independently associated with abnormal cardiac function in pwCF (male sex: OR 3.94 (1.56; 9.95), p = 0.004 and FEV1/FVC ratio: OR 2.05 per 0.1 unit decrease (1.21; 3.52), p = 0.008, respectively). ConclusionsBoth left- and right-sided cardiac alterations were found in pwCF. After adjustments for risk factors, both RV and LV systolic measures remained altered in pwCF, compared to controls. Male sex and decreasing pulmonary function evaluated by FEV1/FVC-ratio were associated with abnormal cardiac function in pwCF.

Elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis and rare mutations.

The triple combination of elexacaftor/tezacaftor/ivacaftor (ETI) has dramatically improved the outcome of people with Cystic Fibrosis (pwCF) with at least one F508del mutation. However, carriers of rare cystic fibrosis transmembrane conductance regulator (CFTR) variants are not candidates for this innovative treatment. In this observational study, we report the results of the compassionate use of ETI in 10 pwCF carriers of rare mutations after 2 months of treatment. Rectal organoids and short-term cultures of nasal epithelium obtained from rectal suction biopsies and nasal brushing were obtained from four subjects. After 2 months of ETI, all patients (4 males, mean age 30.1 ± 13.3 years) showed a significant increase of FEV1% predicted values [+8.0 (3.5-12.7) %, p < 0.010], body mass index [+0.85 (0-1.22) kg/m2, p < 0.020] and cystic fibrosis questionnaire-revised [+19.5 (6.3-29.2) points, p < 0.009]. A significant decrease of sweat chloride concentration [-11.2 (-1.7 to -34.0) mmol/L, p < 0.020] and exacerbations [-1.5 (-2 to -1), p < 0.008] was also recorded. Overall, 7 out of 10 participants were considered full responders. All patients reported cough disappearance (n = 3) or reduction (n = 7). Long-term oxygen was discontinued in two out of three patients and one also stopped noninvasive ventilation and was removed from the lung transplantation waiting list. Despite the limited number of cases, our results support the use of CFTR modulators in patients with rare CFTR variants that are not currently approved for ETI in Europe.

SP-101, A Novel Adeno-Associated Virus Gene Therapy for the Treatment of Cystic Fibrosis, Mediates Functional Correction of Primary Human Airway Epithelia From Donors with Cystic Fibrosis.

Cystic fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein. Although CF affects multiple organs, lung disease is the main cause of morbidity and mortality, and gene therapy is expected to provide a mutation-agnostic option for treatment. SP-101 is a recombinant adeno-associated virus (AAV) gene therapy vector carrying a human CFTR minigene, hCFTRΔR, and is being investigated as an inhalation treatment for people with CF. To further understand SP-101 activity, in vitro studies were performed in human airway epithelia (HAE) derived from multiple CF and non-CF donors. SP-101 restored CFTR-mediated chloride conductance, measured via Ussing chamber assay, at a multiplicity of infection (MOI) as low as 5E2 in the presence of doxorubicin, a small molecule known to augment AAV transduction. Functional correction of CF HAE increased with increasing MOI and doxorubicin concentration and correlated with increasing cell-associated vector genomes and hCFTRΔR mRNA expression. Tropism studies using a fluorescent reporter vector and single-cell mRNA sequencing of SP-101-mediated hCFTRΔR mRNA demonstrated broad expression in all cell types after apical transduction, including secretory, ciliated, and basal cells. In summary, SP-101, particularly in combination with doxorubicin, shows promise for a novel CF treatment strategy and strongly supports continued development.

Development and clinical implementation of an LC-HRMS method for ivacaftor, lumacaftor, tezacaftor and elexacaftor in human plasma and breast milk.

The four cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulators, ivacaftor, lumacaftor, tezacaftor, and elexacaftor, have revolutionised the treatment of CF by direct action on the protein target behind the disease's development. The aim was to develop and validate a quantification method for these CFTR modulators in plasma and breast milk to better understand inter-patient variability in pharmacokinetics and treatment outcome, including the risk of adverse drug reactions. The ability to monitor CFTR modulators in breast milk enables the estimation of the exposure of breastfed infant, with a potential concern for CFTR modulator-induced liver injury. The analysis was performed on a Thermo Vanquish Flex Binary UHPLC system coupled to a high-resolution mass spectrometer (HRMS), Thermo Q Exactive. The analytes were detected using positive electrospray ionisation in full scan mode. After sample preparation by protein precipitation, the supernatant was injected onto the LC system and the analytes were separated using a Zorbax SB-C18 Rapid Res HPLC column (3.5µm, 4.6 × 75mm). This is the first published method for CFTR modulators in breast milk. The validated quantification range for ivacaftor is 0.0050-10µg/mL with a coefficient of variation < 6% and a mean accuracy of 97-106%; for lumacaftor, tezacaftor, and elexacaftor, the validated quantification range is 0.050-100µg/mL with a coefficient of variation < 8% and a mean accuracy 93-106%. A simple and sensitive quantification method for CFTR modulators has been developed and used for routine analysis of human plasma and breast milk samples since 2022.

A review of proton pump inhibitor use in cystic fibrosis and considerations for deprescribing.

Use of proton-pump inhibitors (PPIs) is common among people with cystic fibrosis (pwCF) both for the management of suspected GERD, as well as pancreatic enzyme replacement therapy augmentation. Despite their use, limited data exist to demonstrate a clinically significant impact of PPIs on key endpoints in pwCF. Furthermore, the advent of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy may modify the need for use. These notions, coupled with the potential for adverse outcomes associated with long-term PPI use in pwCF, should facilitate re-evaluation of long-term PPI use in pwCF and promote potential deprescribing. Despite limited data on PPI deprescribing in pwCF, it intuitively mirrors the existing guidance in adults in the general population, but with added consideration given to tapering strategy, and monitoring for CF-specific outcomes such as nutritional and respiratory status. The development of a monitoring and re-initiation plan is key to reducing deprescribing inertia. This review aims to summarize the evidence that details the concern for long-term use of PPIs and provide CF clinicians with rationale and guidance on how to approach deprescribing in their practice.

Assessing the health impacts of parenthood on people with cystic fibrosis: the HOPeCF prospective cohort protocol

IntroductionPeople with cystic fibrosis (CF) are living longer and healthier lives with a growing number considering and pursuing parenthood. The decision of whether to become a parent is complex for...

Kidney effects of triple CFTR modulator therapy in people with cystic fibrosis.

Elexacaftor/tezacaftor/ivacaftor (ETI) is a new cystic fibrosis transmembrane conductance regulator (CFTR) modulator that has transformed the respiratory prognosis of people with cystic fibrosis (pwCF). However, its impact on other organs such as the kidneys, where CFTR is expressed, remains unclear. Since pwCF are risk of both kidney disease and urolithiasis, we aimed to study the potential effects of ETI on renal function, volume status, and risk factors for urolithiasis. This prospective, observational, single-center, before-after cohort study, involved adult pwCF eligible for ETI. The changes in plasma and urinary profiles were assessed by comparing renal function (using 2021 CKD-EPIcreatinine and 2021 CKD-EPIcreatinine-cystatin C formulas), volume status (using aldosterone/renin ratio and blood pressure), and risk factors for urolithiasis, at the time of ETI introduction (M0) and 7 months after (M7). Nineteen pwCF were included. No significant change in renal function was observed between M0 and M7 (2021 CKD-EPIcreatinine: 105.5ml/min/1.73 m² at M0 vs. 103.3ml/min/1.73 m² at M7; P=.17). There was a significant reduction in aldosterone level (370.3pmol/l at M0 vs. 232.4pmol/l at M7; P=.02) and aldosterone/renin ratio (33.6 at M0 vs. 21.8 at M7; P=.03). Among the risk factors for urolithiasis, a significant reduction in magnesuria level was found (4.6mmol/d at M0 vs. 3.8mmol/d at M7; P=.01). These findings suggest that ETI seem to have no short-term impact on the renal function of adult pwCF and appears to correct secondary hyperaldosteronism due to excessive sweat losses. Further investigations are needed to determine the potential impact of decreased magnesuria observed under ETI therapy on the risk of urolithiasis.

Pregnancy and fertility in people with cystic fibrosis following lung transplantation.

The purpose of this review is to summarize available data on fertility, fertility preservation, pregnancy and parenthood following lung transplantation for people with cystic fibrosis (pwCF). In the era of cystic fibrosis transmembrane conductance regulator (CFTR) modulator use, oral therapies that positively impact fundamental CFTR protein abnormalities, the number of pregnancies has increased dramatically with a concomitant decrease in lung transplantation. Nonetheless, some pwCF still require lung transplantation as a life-saving measure, and a fraction of those individuals desires parenthood. Cystic fibrosis (CF) providers infrequently discuss fertility preservation with pwCF, and pwCF feel uneducated about their fertility options posttransplant. However, because the immunosuppression required to successfully maintain lung allografts may impact future fertility, pwCF should receive genetic and reproductive counseling prior to lung transplantation. While pregnancies posttransplantation are high-risk, selected females with CF may be able to pursue this path to parenthood. Although there is a paucity of data specific to pwCF who have undergone lung transplantation, recently developed general guidelines should inform discussions regarding fertility, pregnancy and parenthood in pwCF who desire parenthood following lung transplantation for optimal shared decision-making.

Gastrointestinal Histology in Knoack Out Mouse Models and Temporal Induction of CFTR Protein Function in Mice

Gastrointestinal Histology in Knoack Out Mouse Models and Temporal Induction of CFTR Protein Function in Mice

Lentiviral vector gene therapy and CFTR modulators show comparable effectiveness in cystic fibrosis rat airway models.

Mutation-agnostic treatments such as airway gene therapy have the potential to treat any individual with cystic fibrosis (CF), irrespective of their CF transmembrane conductance regulator (CFTR) gene variants. The aim of this study was to employ two CF rat models, Phe508del and CFTR knockout (KO), to assess the comparative effectiveness of CFTR modulators and lentiviral (LV) vector-mediated gene therapy. Cells were isolated from the tracheas of rats and used to establish air-liquid interface (ALI) cultures. Phe508del rat ALIs were treated with the modulator combination, elexacaftor-tezacaftor-ivacaftor (ETI), and separate groups of Phe508del and KO tracheal epithelial cells were treated with LV-CFTR followed by differentiation at ALI. Ussing chamber measurements were performed to assess CFTR function. ETI-treated Phe508del ALI cultures demonstrated CFTR function that was 59% of wild-type level, while gene-addition therapy restored Phe508del to 68% and KO to 47% of wild-type level, respectively. Our findings show that rat Phe508del-CFTR protein can be successfully rescued with ETI treatment, and that CFTR gene-addition therapy provides significant CFTR correction in Phe508del and KO ALI cultures to levels that were comparable to ETI. These findings highlight the potential of an LV vector-based gene therapy for the treatment of CF lung disease.

Pharmacological and pre-clinical safety profile of rSIV.F/HN, a hybrid lentiviral vector for cystic fibrosis gene therapy.

Cystic fibrosis (CF) is caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene. CFTR modulators offer significant improvements, but approximately 10% of patients remain nonresponsive or are intolerant. This study provides an analysis of rSIV.F/HN, a lentiviral vector optimized for lung delivery, including CFTR protein expression, functional correction of CFTR defects and genomic integration site analysis in preparation for a first-in-human clinical trial. Air-liquid interface cultures of primary human bronchial epithelial cells (HBEC) from CF patients (F508del/F508del), as well as a CFTR-deficient immortalized human lung epithelial cell line mimicking Class I (CFTR-null) homozygous mutations, were used to assess transduction efficiency. Quantification methods included a novel proximity ligation assay (PLA) for CFTR protein expression. For assessment of CFTR channel activity, Ussing chamber studies were conducted. The safety profile was assessed using integration site analysis and in vitro insertional mutagenesis studies. rSIV.F/HN expressed CFTR and restored CFTR-mediated chloride currents to physiological levels in primary F508del/F508del HBECs as well as in a Class I cells. In contrast, the latter could not be achieved by small-molecule CFTR modulators, underscoring the potential of gene therapy for this mutation class. Combination of rSIV.F/HN-CFTR with the potentiator ivacaftor showed a greater than additive effect. The genomic integration pattern showed no site predominance (frequency of occurrence ≤10%), and a low risk of insertional mutagenesis was observed in an in vitro immortalization assay. The results underscore rSIV.F/HN as a promising gene therapy vector for CF, providing a mutation-agnostic treatment option.

Synthesis and Biological Evaluation of Pyrazole-Pyrimidones as a New Class of Correctors of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR).

Cystic fibrosis (CF) is caused by the functional expression defect of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Despite the recent success in CFTR modulator development, the available correctors only partially restore the F508del-CFTR channel function, and several rare CF mutations show resistance to available drugs. We previously identified compound 4172 that synergistically rescued the F508del-CFTR folding defect in combination with the existing corrector drugs VX-809 and VX-661. Here, novel CFTR correctors were designed by applying a classical medicinal chemistry approach on the 4172 scaffold. Molecular docking and three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were conducted to propose a plausible binding site and design more potent and effective analogs. We identified three optimized compounds, which, in combination with VX-809 and the investigational corrector 3151, increased the plasma membrane density and function of F508del-CFTR and other rare CFTR mutants resistant to the currently approved therapies.

Variability in Disease Severity Among Cystic Fibrosis Patients carrying Residual Function Variants: Data from the European Cystic Fibrosis Society Patient Registry

BackgroundCystic Fibrosis (CF) variants that exhibit residual function (RF) of the CF transmembrane conductance regulator (CFTR) are considered to have a milder disease, however, the spectrum of CF phenotype within the different RF variants has not been extensively investigated.AimTo characterise the spectrum of CF disease severity in people with CF (pwCF) carrying different RF variants, using the European CF Society Patient Registry (ECFSPR) data.MethodsA retrospective cross-sectional and longitudinal cohort study included data from the ECFSPR during 2008–2016. Demographic and clinical characteristics of pwCF carrying different RF variants were compared to pwCF homozygous for F508del. Among RF, a distinction was made between pwCF carrying class IV or class V variants and pwCF carrying specific RF variants.ResultsOut of 56 701 pwCF in the ECFSPR, 6192 carried RF variants and 22 766 were homozygous for F508del. Class IV/F508del variants were associated with a milder course compared to class V/F508del, both were milder than pwCF homozygous for F508del. FEV1pp declined already in childhood in all groups. For adults, the hazard ratio of death for class V/F508delversusClass IV/F508del was 2.14 (0.99–4.63, p=0.052). PwCF carrying 3849+10kbC&gt;T/F508del and pwCF carrying R334W/F508del had age-specific FEV1pp and chronic bacterial colonisation similar to pwCF homozygous for F508del.ConclusionThere is a wide spectrum of disease severity between the different RF variants, while some such as 3849+10kbC&gt;T have a a severe disease, which is similar to pwCF homozygous for F508del.

Gut epithelial electrical cues drive differential localization of enterobacteria.

Salmonella translocate to the gut epithelium via microfold cells lining the follicle-associated epithelium (FAE). How Salmonella localize to the FAE is not well characterized. Here we use live imaging and competitive assays between wild-type and chemotaxis-deficient mutants to show that Salmonella enterica serotype Typhimurium (S. Typhimurium) localize to the FAE independently of chemotaxis in an ex vivo mouse caecum infection model. Electrical recordings revealed polarized FAE with sustained outward current and small transepithelial potential, while the surrounding villus is depolarized with inward current and large transepithelial potential. The distinct electrical potentials attracted S. Typhimurium to the FAE while Escherichia coli (E. coli) localized to the villi, through a process called galvanotaxis. Chloride flux involving the cystic fibrosis transmembrane conductance regulator (CFTR) generated the ionic currents around the FAE. Pharmacological inhibition of CFTR decreased S. Typhimurium FAE localization but increased E. coli recruitment. Altogether, our findings demonstrate that bioelectric cues contribute to S. Typhimurium targeting of specific gut epithelial locations, with potential implications for other enteric bacterial infections.

Inhalation of SP-101 Followed by Inhaled Doxorubicin Results in Robust and Durable hCFTRΔR Transgene Expression in the Airways of Wild-Type and Cystic Fibrosis Ferrets.

Cystic fibrosis (CF) is a serious genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Approved small molecule therapies benefit the majority of people with CF (pwCF), but unfortunately not all. Gene addition offers a mutation agnostic treatment option for all pwCF. SP-101 is an adeno-associated virus gene therapy vector (AAV2.5T) that has been optimized for efficient human airway cell transduction, and that contains a functional and regulated shortened human CFTR minigene (hCFTRΔR) with a small synthetic promoter/enhancer. To understand SP-101 airway distribution, activity, and the associated immune response, invivo studies were performed in wild-type and CF ferrets. After single dose inhaled delivery of SP-101, followed by single dose inhaled doxorubicin (an AAV transduction augmenter) or saline, SP-101 vector genomes were detected throughout the respiratory tract. hCFTRΔR mRNA expression was highest in ferrets also receiving doxorubicin and persisted for the duration of the study (13 weeks). Pre-existing mucus in the CF ferrets did not present a barrier to effective transduction. Binding and neutralizing antibodies to the AAV2.5T capsid were observed regardless of doxorubicin exposure. Only a portion of ferrets exhibited a weak T-cell response to AAV2.5T and no T-cell response was seen against hCFTRΔR. These data strongly support the continued development of inhaled SP-101, followed by inhaled doxorubicin, for the treatment of CF.