This clinical trial is focused on studying a condition called Ulcerative Colitis, which is a type of inflammatory bowel disease that causes long-lasting inflammation and ulcers in the digestive tract. The study is testing a new treatment called GS-1427, which is taken as a film-coated tablet. The purpose of the study is to evaluate how effective and safe GS-1427 is for adults with moderately to severely active Ulcerative Colitis.

Participants in the study will be randomly assigned to receive either the GS-1427 tablets or a placebo. The study will last for up to 52 weeks, with the main focus on the results at Week 12. During this time, participants will take the medication orally, and their health will be monitored closely to see how well the treatment works and to check for any side effects. The study aims to see if the treatment can help reduce symptoms and improve the condition of the digestive tract.

Throughout the study, researchers will look for improvements in symptoms such as stool frequency and rectal bleeding, as well as overall healing of the digestive tract. The study will also track any adverse events or changes in laboratory tests to ensure the safety of the participants. The ultimate goal is to find out if GS-1427 can provide a new and effective treatment option for people living with Ulcerative Colitis.