Enhancing the anti-multiple myeloma efficiency in a cancer stem cell xenograft model by conjugating the ABCG2 antibody with microbubbles for a targeted delivery of ultrasound mediated epirubicin

Background: Although multiple myeloma (MM) treatment has improved in the last decade, it remains largely incurable. One of main reasons is that there are cancer stem cells (CSCs) in MM, which are respon- sible for MM’s drug resistance and relapse. In this study, we used the targeting microbubbles (MBs) conjugated with anti-ABCG2 monoclonal antibody (mAb) for ultrasound mediated epirubicin (EPI) delivery to evaluate the therapeutic effectiveness of the novel agent in MM CSC xenograft model. Methods: MMCSCs, marked by CD138-CD34- cell phenotypes were isolated from humancMMRPMI8226 cell line using immune magnetic activated cell sorting system, and inoculated into nonobese diabetic/ severe combined immunodeficient mice by subcutaneous or intravenous injection. After the mice developed MM, they were intravenous injection treated with EPI, EPI-MBs + mAb, and EPI-MBs + mAb with ultrasound exposure, respectively. Results: All treated mice showed inhibited tumor sizes or bone lesions, decreased renal damages and ane- mia, and increased MM bearing mice’ survival. In particular, the EPI-MBs + mAb plus ultrasound exhib- ited significantly enhanced therapeutic MM effectiveness by inducing apoptosis compared with other biologic agents. Conclusion: The data provide evidence that EPI-MBs + mAb with ultrasound exposure might be available for treatment MM patients in clinic.