This clinical trial is focused on studying a type of cancer called Mantle Cell Lymphoma, which is a rare form of non-Hodgkin’s lymphoma. The study is comparing the effectiveness and safety of a new treatment called LOXO-305, also known by its code name pirtobrutinib, with other standard treatments chosen by doctors. These standard treatments are known as Bruton’s tyrosine kinase (BTK) inhibitors, which are a type of medication that helps to block certain proteins that encourage cancer cells to grow.

The purpose of the study is to see how well patients with previously treated Mantle Cell Lymphoma respond to pirtobrutinib compared to other BTK inhibitors. Participants in the study will be randomly assigned to receive either pirtobrutinib or a BTK inhibitor chosen by their doctor. The study will monitor the participants over a period of time to see how long they can live without their disease getting worse, which is known as progression-free survival.

During the study, participants will take the medication in the form of tablets, which are taken by mouth. The study will last for up to 48 weeks, and participants will have regular check-ups to monitor their health and the effects of the treatment. Some participants may receive a placebo, which is a tablet that looks like the medication but does not contain the active substance. The study aims to provide valuable information on the best treatment options for patients with Mantle Cell Lymphoma.