Design and Efficacy of a Monovalent Bispecific PD-1/CTLA4 Antibody That Enhances CTLA4 Blockade on PD-1+ Activated T Cells

Cancer Discov. 2021 May;11(5):1100-1117. doi: 10.1158/2159-8290.CD-20-1445. Epub 2021 Jan 8.


The clinical benefit of PD-1 blockade can be improved by combination with CTLA4 inhibition but is commensurate with significant immune-related adverse events suboptimally limiting the doses of anti-CTLA4 mAb that can be used. MEDI5752 is a monovalent bispecific antibody designed to suppress the PD-1 pathway and provide modulated CTLA4 inhibition favoring enhanced blockade on PD-1+ activated T cells. We show that MEDI5752 preferentially saturates CTLA4 on PD-1+ T cells versus PD-1- T cells, reducing the dose required to elicit IL2 secretion. Unlike conventional PD-1/CTLA4 mAbs, MEDI5752 leads to the rapid internalization and degradation of PD-1. Moreover, we show that MEDI5752 preferentially localizes and accumulates in tumors providing enhanced activity when compared with a combination of mAbs targeting PD-1 and CTLA4 in vivo. Following treatment with MEDI5752, robust partial responses were observed in two patients with advanced solid tumors. MEDI5752 represents a novel immunotherapy engineered to preferentially inhibit CTLA4 on PD-1+ T cells. SIGNIFICANCE: The unique characteristics of MEDI5752 represent a novel immunotherapy engineered to direct CTLA4 inhibition to PD-1+ T cells with the potential for differentiated activity when compared with current conventional mAb combination strategies targeting PD-1 and CTLA4. This molecule therefore represents a step forward in the rational design of cancer immunotherapy.See related commentary by Burton and Tawbi, p. 1008.This article is highlighted in the In This Issue feature, p. 995.

Publication types

  • Case Reports

MeSH terms

  • Adenocarcinoma / drug therapy
  • Adenocarcinoma, Clear Cell / drug therapy
  • Antibodies, Monoclonal, Humanized / therapeutic use*
  • CTLA-4 Antigen / metabolism
  • Humans
  • Immunotherapy
  • Kidney Neoplasms / drug therapy
  • Male
  • Middle Aged
  • Programmed Cell Death 1 Receptor / metabolism
  • Stomach Neoplasms / drug therapy
  • T-Lymphocytes / immunology


  • Antibodies, Monoclonal, Humanized
  • CTLA-4 Antigen
  • CTLA4 protein, human
  • Programmed Cell Death 1 Receptor
  • Tovetumab