The blood-brain barrier prevents many drugs from entering the brain. Unfortunately, the same cannot be said for tumor cells. The brain is one of the most frequent locations for cancer metastases, which are then extremely challenging to treat. Now, researchers at the University of California at Los Angeles have developed an encapsulation technique that allowed the delivery of the monoclonal antibody Rituxan (rituximab) to brain metastases of a mouse xenograft model of non-Hodgkin lymphoma.