Gene Therapy Study for Cystic Fibrosis

Study Purpose

The purpose of this study is to evaluate the safety and tolerability of a single dose of 4D-710 delivered via nebulization in people with cystic fibrosis who are not eligible for CFTR modulator therapy or could not tolerate CFTR modulator therapy due to side effects. 4D-710 contains a modified copy of the human CFTR gene packaged in an adeno-associated virus (AAV) capsid that cannot replicate. Absorption of 4D-710 by airway cells should allow them to make functional CFTR protein. Participants in the study undergo a bronchoscopy procedure under sedation during which samples of airway cells are collected to see if 4D-710 works as planned.