When treating metastatic tumors, chemoresistance can cause problems. A report in this issue of Science Translational Medicine demonstrates the potential of nanodiamond carriers (2 to 8 nanometers) for treating cancers with drug-efflux-based chemoresistance. Nanodiamond-mediated delivery of the chemotherapeutic doxorubicin (Dox) allowed for prolonged activity and increased apoptosis with decreased toxicity when compared with free Dox in liver cancer cells in culture as well as in vivo in mouse liver tumors. This finding may represent a broadly applicable strategy for overcoming adenosine 5'-triphosphate (ATP)-binding cassette (ABC) drug transporter-mediated resistance during cancer chemotherapy.