Imaging, Biodistribution, and Dosimetry of Radionuclide-Labeled PD-L1 Antibody in an Immunocompetent Mouse Model of Breast Cancer

Cancer Res. 2016 Jan 15;76(2):472-9. doi: 10.1158/0008-5472.CAN-15-2141. Epub 2015 Nov 10.


The programmed cell death ligand 1 (PD-L1) participates in an immune checkpoint system involved in preventing autoimmunity. PD-L1 is expressed on tumor cells, tumor-associated macrophages, and other cells in the tumor microenvironment. Anti-PD-L1 antibodies are active against a variety of cancers, and combined anti-PD-L1 therapy with external beam radiotherapy has been shown to increase therapeutic efficacy. PD-L1 expression status is an important indicator of prognosis and therapy responsiveness, but methods to precisely capture the dynamics of PD-L1 expression in the tumor microenvironment are still limited. In this study, we developed a murine anti-PD-L1 antibody conjugated to the radionuclide Indium-111 ((111)In) for imaging and biodistribution studies in an immune-intact mouse model of breast cancer. The distribution of (111)In-DTPA-anti-PD-L1 in tumors as well as the spleen, liver, thymus, heart, and lungs peaked 72 hours after injection. Coinjection of labeled and 100-fold unlabeled antibody significantly reduced spleen uptake at 24 hours, indicating that an excess of unlabeled antibody effectively blocked PD-L1 sites in the spleen, thus shifting the concentration of (111)In-DTPA-anti-PD-L1 into the blood stream and potentially increasing tumor uptake. Clearance of (111)In-DTPA-anti-PD-L1 from all organs occurred at 144 hours. Moreover, dosimetry calculations revealed that radionuclide-labeled anti-PD-L1 antibody yielded tolerable projected marrow doses, further supporting its use for radiopharmaceutical therapy. Taken together, these studies demonstrate the feasibility of using anti-PD-L1 antibody for radionuclide imaging and radioimmunotherapy and highlight a new opportunity to optimize and monitor the efficacy of immune checkpoint inhibition therapy.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Breast Neoplasms / genetics
  • Breast Neoplasms / immunology*
  • Breast Neoplasms / pathology
  • Disease Models, Animal
  • Female
  • Humans
  • Male
  • Mice
  • Prognosis
  • Programmed Cell Death 1 Receptor / genetics*
  • Programmed Cell Death 1 Receptor / immunology*
  • Radiotherapy Planning, Computer-Assisted
  • Tumor Microenvironment


  • Programmed Cell Death 1 Receptor