A Study to Assess the Effectiveness and Safety of GSK3862995B in Adults With Bronchiectasis

This study is designed to find out how effective and safe a new drug, GSK3862995B, is for adult participants with bronchiectasis, a chronic lung disease. The study will also test how the body processes the drug and to check for any immune reactions. Participants will be divided into groups randomly to receive either one of two different doses of the study drug or a placebo. The main goal of the study is to see how well the drug works compared to the placebo in helping those with bronchiectasis.

Inclusion Criteria: * Body mass index (BMI) between 18-35 kilograms per square meters (kg/m\^2) * Clinical history consistent with bronchiectasis (cough, chronic sputum production, and/or recurrent respiratory infections) that is confirmed on chest computed tomography (CT) * Meet one of the two criteria: * In the 12 months prior to screening, have had 2 or more documented pulmonary exacerbations that required a new antibiotic prescription by a physician or 1 pulmonary exacerbation that required hospitalization; or * In the 12 months prior to screening, have had 0 or 1 pulmonary exacerbation and a QOL-B RSS of less than (\=) 30 percent (%) or greater of predicted normal value * Non-smokers or former cigarette smokers * Males and females of childbearing and non-childbearing potential * A female participant is eligible to participate if she is not pregnant or breastfeeding * Is a Woman of non-childbearing potential (WONCBP) or is a Woman of childbearing potential (WOCBP) and using a contraceptive method that is highly effective, with a failure rate of \2x Upper limit of normal (ULN) * Total bilirubin \>1.5xULN; Participants with Gilbert's syndrome can be included with total bilirubin \>1.5xULN as long as direct bilirubin is less than or equal to (\