Study Summary: This study is about testing a new drug called **ONO-4685** to see if it is safe and works well for people with a type of cancer called **T-cell lymphoma**. This cancer affects a part of your immune system known as T-cells. The study focuses on patients whose cancer has come back (relapsed) or did not respond to previous treatments (refractory). **Key Points:** - The study is for adults aged 18 or older who have tried at least two other treatments without success. - Participants need to have specific types of T-cell lymphoma and meet certain health criteria to join. - People who join will not have to pay for the study drug, but they need to meet all the health and treatment history requirements. The study will check how well the body handles the drug (pharmacokinetics) and its early effectiveness against the cancer. This study is not for people with certain other health conditions or those who have had specific previous treatments, such as certain types of immune therapy. It's important to talk with a doctor to see if joining is a good idea based on your health and treatment history.