Despite herculean efforts, cancer remains a formidable disease, with each malignant subtype responding differently to therapeutics. One hurdle specific to treating solid tumors is a protective layer called an extracellular matrix that can prevent chemotherapeutic agents from penetrating the tumor's core. Scientists now report results showing that, by cloaking anti-cancer drugs in a specially designed particle, they could target and destroy tumor cells deep inside a malignant mass in vitro.