Comments from the Award Winners

On receiving the Best Poster Award Department of Molecular Pharmacology, National Cancer Center Research Institute Mikiko Suzuki

　I am very honored to receive the prestigious Best Poster Award at the 37th Annual Meeting of the Japanese Society of Pharmacokinetics for the presentation entitled “Imaging Analysis of Antigen Dependence and Heterogeneity of Intratumor Distribution of Antibody Drugs Using Highly Brilliant Fluorescent Nanoparticles”. I would like to express my sincere gratitude to Dr. Hideki Hirabayashi, the President of the Annual Meeting, the selection committee members, and all the people involved in the Japanese Pharmacokinetics Society.

　PID-imaging, which uses highly brilliant fluorescent nanoparticles (phosphor integrated dots; PID) as labeling probes, is a next-generation imaging analysis technology that combines high sensitivity and quantitativeness not found in conventional immunostaining. PID-imaging can be performed on any target for which antibodies can be obtained, and can be used for multiple staining with general immunostaining. In this study, PID-imaging was used to evaluate the distribution of anti-HER2 antibody trastuzumab using a patient tumor xenograft model (PDX model), which is considered to better reflect the tumor microenvironment and heterogeneity of the patient tumor than the conventional cell line xenograft model (CDX model).

　The number of Trastuzumab bound per cell showed that the distribution of Trastuzumab in the PDX model was more strongly heterogeneous than in the CDX model, and was not necessarily dependent on HER2 expression. Vascular distribution may be one of the factors contributing to the heterogeneity, and the distribution of Trastuzumab was shown to be dependent on the distance from the blood vessels. These results suggest that PID-imaging may be useful for visualizing and quantifying the distribution of antibody drugs in tumor tissues and for elucidating the relationship between the tumor microenvironment and pharmacokinetics, and are expected to be applied to many drugs and non-clinical and clinical studies.

　Finally, this research was conducted in collaboration with Konica Minolta, Inc. We would like to take this opportunity to express our sincere gratitude to Konica Minolta, Inc. We would also like to thank Dr. Tetsunobu Hamada, Director of the Division of Molecular Pharmacology, National Cancer Center Research Institute, for his guidance in conducting this research, as well as the laboratory staff for their support.