ABSTRACT
Radiotherapy demonstrates a synergistic effect with immunotherapy by inducing a transformation of "immune cold" tumors into "immune hot" tumors in triple negative breast cancer (TNBC). Nevertheless, the effectiveness of immunotherapy is constrained by low expression of tumor-exposed antigens, inadequate inflammation, and insufficient tumor infiltrating lymphocyte (TILs). To address this predicament, novel lutecium-based rare earth nanoparticles (RENPs) are synthesized with the aim of amplifying radiation effect and tumor immune response. The nanoprobe is characterized by neodymium-based down-conversion fluorescence, demonstrating robust photostability, biocompatibility, and targetability. The conjugation of RENPs with a CXCR4 targeted drug enables precise delineation of breast tumors using a near-infrared imaging system and improves radiation efficacy via lutetium-based radio-sensitizer in vivo. Furthermore, the study shows a notable enhancement of immune response through the induction of immunogenic cell death and recruitment of TILs, resulting in the inhibition of tumor progression both in vitro and in vivo models following the administration of nanoparticles. Hence, the novel multifunctional nanoprobes incorporating various lanthanide elements offer the potential for imaging-guided tumor delineation, radio-sensitization, and immune activation post-radiation, thus presenting an efficient radio-immunotherapeutic approach for TNBC.
ABSTRACT
The CDK4/6-Rb axis is a crucial target of cancer therapy and several selective inhibitors of it have been approved for clinical application. However, current therapeutic efficacy evaluation mostly relies on anatomical imaging, which cannot directly reflect changes in drug targets, leading to a delay in the selection of optimal treatment. In this study, we constructed a novel fluorescent probe, CPP30-Lipo/CDKACT4, for real-time monitoring of CDK4 activity and the therapeutic efficacy of its inhibitor in HR+/HER2- breast cancer. CPP30-Lipo/CDKACT4 exhibited good optical stability and targetability. The signal of the probe in living cells decreased after CDK4 knockdown or palbociclib treatment. Moreover, the fluorescence intensity of the tumors after 7 days of palbociclib treatment was significantly lower than that before treatment, while no significant change in tumor diameter was observed under magnetic resonance imaging. Overall, we developed an innovative fluorescent probe that can monitor CDK4 activity and the early therapeutic response to CDK4 inhibitors in living cells and in vivo. It may provide a new strategy for evaluating antitumor therapeutic efficacy in a clinical context and for drug development.
