NHLBI/CFF Workshop: Advancing Gene Editing Technologies for the Treatment of Cystic Fibrosis Lung Disease

Background

Cystic fibrosis is a recessively inherited disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (cftr) gene.  The protein product, CFTR, is an anion channel expressed in the epithelia of numerous organs throughout the body that is responsible for regulating fluid absorption and secretion.  In the lungs, mutations in CFTR cause the airway surface liquid to dehydrate, disrupting mucociliary clearance.  This leads to the accumulation of mucus, chronic infections and inflammation, and ultimately lung failure.

Significant advances have been made to treat the underlying cause of CF with the creation of therapeutics, known as correctors and potentiators, that target specific mutations in the CFTR protein.  However, these therapeutics are not likely to work in all patients, especially those who completely lack expression of the CFTR protein.  Furthermore, these therapeutics, while effective, are not able to cure the disease.  Patients will still suffer from the disease; experiencing a gradual loss in lung function, mucus buildup, and chronic infection.  Thus, there is a critical need to develop novel therapeutics that can be applied to all CF patients.  A therapeutic application of gene editing has the potential to permanently correct the genetic mutations that cause CF.  However, realizing this goal will be a significant challenge as there are numerous scientific and technical barriers that need to be overcome.

Discussion

Development and implementation of gene editing therapies for the treatment of cystic fibrosis will require a multidisciplinary approach with significant collaboration between investigators from various scientific backgrounds.  To help facilitate future collaborations and identify scientific priorities in the field, the workshop included presentations and discussions on such topics as optimizing gene editing technologies for the lung, mitigating off-target editing, in vitro and in vivo model systems for evaluating safety and efficacy, viral and non-viral delivery vehicles, lung cell populations, overcoming the mucus barrier, and strategies to optimize delivery to the lung.  After extensive discussion, the workshop participants made the following recommendations:

1. Develop and optimize gene editing technologies for the CFTR gene locus
   1. Develop technologies and strategies that can be applied to the 1,000+ known CFTR mutations
   2. Determine how regulatory elements and intronic enhancer sequences contribute to the expression of CFTR
2. Improve our understanding of the basic pathobiology of cystic fibrosis
   1. Determine the necessary level of CFTR expression to prevent or reverse disease and if expression of CFTR in specific regions of the lung is required
   2. Identify and characterize the disease relevant cells in the airway epithelium
   3. Determine the role of the submucosal glands in disease pathogenesis and if correction of CFTR in the glands is essential
3. Develop better model systems that can more accurately evaluate gene editing safety and efficacy
   1. Optimize in vitro models of the lung, such as lung-on-a-chip technologies, to evaluate gene editing technologies
   2. Develop animal models that express normal human CFTR and mutant alleles to better evaluate efficacy of targeted gene editing technologies and delivery vehicles
4. Develop new technologies to specifically and accurately deliver gene editing therapies to the lungs
   1. Develop delivery vehicles that can efficiently navigate through airway mucus and avoid removal by the immune system
   2. Determine the optimal time and route of administration to deliver gene editing therapies to the lungs
   3. Develop delivery vehicles that can specifically target the disease relevant cells in the airways, including progenitor cells

NHLBI Contact

John Sheridan, PhD

Division of Lung Disease, NHLBI

Workshop Co-Chairs

• Marie Egan, MD – Yale University
• Justin Hanes, PhD – Johns Hopkins University

Non-Federal Workshop Participants

• Daniel Anderson, PhD – Massachusetts Institute of Technology
• Aravind Asokan, PhD – University of North Carolina at Chapel Hill
• Christina Barkauskas, MD – Duke University
• Richard Boucher, MD – University of North Carolina at Chapel Hill
• Emanuela Bruscia, PhD – Yale University
• Amit Choudhary, PhD – Harvard Medical School
• James Dahlman, PhD – Georgia Institute of Technology
• Brian Davis, PhD – University of Texas Health Science Center at Houston
• Stephanie Davis, MD – Indiana University
• Mitchell Drumm, PhD – Case Western Reserve University
• Debadyuti (Rana) Ghosh, PhD – University of Texas Austin
• Peter Glazer, MD, PhD – Yale University
• Ann Harris, PhD – Case Western Reserve University
• Dongeun (Dan) Huh, PhD – University of Pennsylvania
• Paul McCray, MD – University of Iowa
• Matthew Porteus, MD, PhD – Stanford University
• Jason Rock, PhD – Boston University
• Steven Rowe, MD, MSPH – University of Alabama at Birmingham
• Gaurav Sahay, PhD – Oregon State University and Oregon Health Science University
• Mark Saltzman, PhD – Yale University
• Daniel Siegwart, PhD – University of Texas Southwestern Medical Center
• William Skach, MD – Cystic Fibrosis Foundation
• Hans-Willem Snoeck, MD, PhD – Columbia University
• Eric Sorscher, MD – Emory University
• Jung Soo Suk, MSE, PhD – Johns Hopkins University
• Katherine Tuggle, PhD – Cystic Fibrosis Foundation
• James Wilson, MD, PhD – University of Pennsylvania
• Wen Xue, PhD – University of Massachusetts Medical School

Federal Workshop Participants

• Thomas Croxton, MD, PhD – NHLBI
• Thomas Eggerman, MD, PhD – NIDDK
• Ying Huang, PhD – FDA
• Roya Kalantari, PhD – NHLBI
• James Kiley, PhD – NHLBI
• John Sheridan, PhD – NHLBI