Additional Study Information: This research study is evaluating an investigational drug, called cirmtuzumab, in combination with astandard drug, called ibrutinib (Imbruvica), as a possible treatment for patients with CLL/SLL or MCL. All cells in the body receive signals to grow and survive, but sometimes these signals get out of control, causing too much cell growth. When the growth of lymphocytes (a type of infection-fighting white blood cell) gets out of control, cancers like CLL/SLL or MCL can develop. Drugs like ibrutinib can kill some of the CLL/SLL or MCL cells and can help control the disease. Drugs like cirmtuzumab may block some ofthe cell signals that cause CLL/SLL or MCL to grow and survive and may also help control the disease. Based on data from animals, it appears possible that giving ibrutinib together with cirmtuzumab may have more activity against the cancer disease process than giving ibrutinib alone.