PD-L1 Detection in Tumors Using [64Cu]Atezolizumab with PET

Wojciech Lesniak, Samit Chatterjee, Matthew Gabrielson, Ala Lisok, Bryan Wharram, Martin Gilbert Pomper, Sridhar Nimmagadda

Research output: Contribution to journalArticle

Abstract

The programmed death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) pair is a major immune checkpoint pathway exploited by cancer cells to develop and maintain immune tolerance. With recent approvals of anti-PD-1 and anti-PD-L1 therapeutic antibodies, there is an urgent need for noninvasive detection methods to quantify dynamic PD-L1 expression in tumors and to evaluate the tumor response to immune modulation therapies. To address this need, we assessed [64Cu]atezolizumab for the detection of PD-L1 expression in tumors. Atezolizumab (MPDL3208A) is a humanized, human and mouse cross-reactive, therapeutic PD-L1 antibody that is being investigated in several cancers. Atezolizumab was conjugated with DOTAGA and radiolabeled with copper-64. The resulting [64Cu]atezolizumab was assessed for in vitro and in vivo specificity in multiple cell lines and tumors of variable PD-L1 expression. We performed PET-CT imaging, biodistribution, and blocking studies in NSG mice bearing tumors with constitutive PD-L1 expression (CHO-hPD-L1) and in controls (CHO). Specificity of [64Cu]atezolizumab was further confirmed in orthotopic tumor models of human breast cancer (MDAMB231 and SUM149) and in a syngeneic mouse mammary carcinoma model (4T1). We observed specific binding of [64Cu]atezolizumab to tumor cells in vitro, correlating with PD-L1 expression levels. Specific accumulation of [64Cu]atezolizumab was also observed in tumors with high PD-L1 expression (CHO-hPD-L1 and MDAMB231) compared to tumors with low PD-L1 expression (CHO, SUM149). Collectively, these studies demonstrate the feasibility of using [64Cu]atezolizumab for the detection of PD-L1 expression in different tumor types.

Original languageEnglish (US)
Pages (from-to)2103-2110
Number of pages8
JournalBioconjugate Chemistry
Volume27
Issue number9
DOIs
StatePublished - Sep 21 2016

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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