This clinical trial focuses on monitoring the long-term health of individuals with cystic fibrosis who previously participated in a study involving a treatment called BI 3720931. Cystic fibrosis is a genetic condition that affects the lungs and digestive system, leading to severe respiratory and digestive problems. The treatment being studied, BI 3720931, is an inhaled gene therapy designed to help manage the symptoms of cystic fibrosis. The purpose of this study is to evaluate the long-term safety and effectiveness of this treatment.

Participants in this study have already received at least one dose of BI 3720931 or a matching placebo in a previous trial. The study will follow these participants over an extended period to observe any potential long-term effects of the treatment. This includes monitoring for any new health issues such as serious infections, neurological disorders, or autoimmune conditions. The study will also track the time it takes for any loss of treatment effectiveness, particularly in lung function, which is measured by a test called forced expiratory volume in 1 second (FEV1).

The study is designed to last up to 15 years, allowing researchers to gather comprehensive data on the long-term impact of BI 3720931. Throughout this period, the occurrence of any serious adverse events will be recorded, providing valuable insights into the safety profile of the treatment. This information will help determine the potential benefits and risks of using BI 3720931 as a long-term treatment option for people with cystic fibrosis.