Blockade of the PD-1/PD-L1 axis augments lysis of AML cells by the CD33/CD3 BiTE antibody construct AMG 330: reversing a T-cell-induced immune escape mechanism

Leukemia. 2016 Feb;30(2):484-91. doi: 10.1038/leu.2015.214. Epub 2015 Aug 4.


Bispecific T-cell engagers (BiTEs) are very effective in recruiting and activating T cells. We tested the cytotoxicity of the CD33/CD3 BiTE antibody construct AMG 330 on primary acute myeloid leukemia (AML) cells ex vivo and characterized parameters contributing to antileukemic cytolytic activity. The E:T ratio and the CD33 expression level significantly influenced lysis kinetics in long-term cultures of primary AML cells (n=38). AMG 330 induced T-cell-mediated proinflammatory conditions, favoring the upregulation of immune checkpoints on target and effector cells. Although not constitutively expressed at the time of primary diagnosis (n=123), PD-L1 was strongly upregulated on primary AML cells upon AMG 330 addition to ex vivo cultures (n=27, P<0.0001). This phenomenon was cytokine-driven as the sole addition of interferon (IFN)-γ and tumor necrosis factor-α also induced expression. Through blockade of the PD-1/PD-L1 interaction, AMG 330-mediated lysis (n=9, P=0.03), T-cell proliferation (n=9, P=0.01) and IFN-γ secretion (n=8, P=0.008) were significantly enhanced. The combinatorial approach was most beneficial in settings of protracted AML cell lysis. Taken together, we have characterized a critical resistance mechanism employed by primary AML cells under AMG 330-mediated proinflammatory conditions. Our results support the evaluation of checkpoint molecules in upcoming clinical trials with AMG 330 to enhance BiTE antibody construct-mediated cytotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Bispecific / pharmacology*
  • B7-H1 Antigen / analysis
  • B7-H1 Antigen / antagonists & inhibitors*
  • B7-H1 Antigen / physiology
  • Humans
  • Leukemia, Myeloid, Acute / drug therapy*
  • Leukemia, Myeloid, Acute / immunology
  • Leukemia, Myeloid, Acute / pathology
  • Mice
  • Programmed Cell Death 1 Receptor / analysis
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors*
  • Programmed Cell Death 1 Receptor / physiology
  • Sialic Acid Binding Ig-like Lectin 3 / analysis
  • T-Lymphocytes / immunology*
  • Tumor Escape / drug effects*


  • Antibodies, Bispecific
  • B7-H1 Antigen
  • CD274 protein, human
  • CD33 protein, human
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • Sialic Acid Binding Ig-like Lectin 3
  • AMG 330