This clinical trial is focused on studying a type of cancer called Follicular Lymphoma. Follicular Lymphoma is a slow-growing form of non-Hodgkin lymphoma, which is a cancer that affects the lymphatic system, a part of the immune system. The study is investigating the effects of a medication called Ibrutinib, which is taken as a hard capsule by mouth. Ibrutinib is being tested in combination with another medication called Rituximab, which is commonly used to treat this type of cancer. The trial will compare the combination of Ibrutinib and Rituximab to a combination of a placebo and Rituximab.

The purpose of the study is to see if adding Ibrutinib to Rituximab can help patients live longer without their disease getting worse, which is known as progression-free survival. Participants in the study will be randomly assigned to receive either the Ibrutinib and Rituximab combination or the placebo and Rituximab combination. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual medication or the placebo. This helps ensure that the results are not biased.

Throughout the study, participants will receive regular check-ups and monitoring to assess their health and the effects of the treatment. The study will also look at other outcomes, such as the overall response rate, which measures how well the cancer responds to the treatment, and overall survival, which tracks how long participants live after starting the treatment. The trial aims to provide valuable information on whether the addition of Ibrutinib can improve outcomes for patients with Follicular Lymphoma.