Design and Preclinical Evaluation of a Novel B7-H4-Directed Antibody-Drug Conjugate, AZD8205, Alone and in Combination with the PARP1-Selective Inhibitor AZD5305

Clin Cancer Res. 2023 Mar 14;29(6):1086-1101. doi: 10.1158/1078-0432.CCR-22-2630.


Purpose: We evaluated the activity of AZD8205, a B7-H4-directed antibody-drug conjugate (ADC) bearing a novel topoisomerase I inhibitor (TOP1i) payload, alone and in combination with the PARP1-selective inhibitor AZD5305, in preclinical models.

Experimental design: IHC and deep-learning-based image analysis algorithms were used to assess prevalence and intratumoral heterogeneity of B7-H4 expression in human tumors. Several TOP1i-ADCs, prepared with Val-Ala or Gly-Gly-Phe-Gly peptide linkers, with or without a PEG8 spacer, were compared in biophysical, in vivo efficacy, and rat toxicology studies. AZD8205 mechanism of action and efficacy studies were conducted in human cancer cell line and patient-derived xenograft (PDX) models.

Results: Evaluation of IHC-staining density on a per-cell basis revealed a range of heterogeneous B7-H4 expression across patient tumors. This informed selection of bystander-capable Val-Ala-PEG8-TOP1i payload AZ14170133 and development of AZD8205, which demonstrated improved stability, efficacy, and safety compared with other linker-payload ADCs. In a study of 26 PDX tumors, single administration of 3.5 mg/kg AZD8205 provided a 69% overall response rate, according to modified RECIST criteria, which correlated with homologous recombination repair (HRR) deficiency (HRD) and elevated levels of B7-H4 in HRR-proficient models. Addition of AZD5305 sensitized very low B7-H4-expressing tumors to AZD8205 treatment, independent of HRD status and in models representing clinically relevant mechanisms of PARPi resistance.

Conclusions: These data provide evidence for the potential utility of AZD8205 for treatment of B7-H4-expressing tumors and support the rationale for an ongoing phase 1 clinical study (NCT05123482). See related commentary by Pommier and Thomas, p. 991.

Publication types

  • Editorial
  • Research Support, Non-U.S. Gov't
  • Comment

MeSH terms

  • Animals
  • Humans
  • Immunoconjugates* / pharmacology
  • Immunoconjugates* / therapeutic use
  • Neoplasms* / drug therapy
  • Poly (ADP-Ribose) Polymerase-1 / genetics
  • Poly(ADP-ribose) Polymerase Inhibitors / pharmacology
  • Poly(ADP-ribose) Polymerase Inhibitors / therapeutic use
  • Rats
  • Topoisomerase I Inhibitors


  • Immunoconjugates
  • Topoisomerase I Inhibitors
  • AZD5305
  • Poly(ADP-ribose) Polymerase Inhibitors
  • PARP1 protein, human
  • Poly (ADP-Ribose) Polymerase-1
  • Parp1 protein, rat