Grommes C, et al. - Authors analyzed in this Phase Ib clinical trial to investigate the effects of the sequential combination of ibrutinib at 560 or 840 mg daily dosing with methotrexate (HD-MTX) and rituximab in subjects with central nervous system lymphoma (CNSL). They found the combination of the 3 was well endured with an agreeable safety profile and no dose-limiting toxicity. They also observed sustained tumor responses linked to the removal of circulating tumor DNA (ctDNA) from the cerebrospinal fluid (CSF).