SYD985, a novel duocarmycin-based HER2-targeting antibody-drug conjugate, shows promising antitumor activity in epithelial ovarian carcinoma with HER2/Neu expression

Gynecol Oncol. 2017 Jul;146(1):179-186. doi: 10.1016/j.ygyno.2017.04.023. Epub 2017 May 1.

Abstract

Background: Epithelial ovarian cancer (EOC) is an aggressive and heterogeneous disease. <10% of EOC demonstrate HER2/neu 3+ receptor over-expression. However, moderate to low (i.e., 2+ and 1+) HER2/neu expression is reported in up to 50% of EOC. The objective of this study was to compare the anti-tumor activity of SYD985, a novel HER2-targeting antibody-drug conjugate (ADC), to trastuzumab emtansine (T-DM1) in EOC models with differential HER2/neu expression.

Methods: The cytotoxicity of SYD985 and T-DM1 was evaluated using ten primary EOC cell lines with 0/1+, 2+, and 3+ HER2/neu expression in antibody-dependent cellular cytotoxicity (ADCC), proliferation, viability and bystander killing experiments. Finally, the in vivo activity of SYD985 and T-DM1 was also studied in ovarian cancer xenografts.

Results: SYD985 and T-DM1 induced similar ADCC in the presence of peripheral blood lymphocytes (PBL) against EOC cell lines with differential HER2/neu expression. In contrast, SYD985 was 3 to 42 fold more cytotoxic in the absence of PBL when compared to T-DM1 (p<0.0001). Unlike T-DM1, SYD985 induced efficient bystander killing of HER2/neu 0/1+ tumor cells when admixed with HER2/neu 3+ EOC cells. In vivo studies confirmed that SYD985 is significantly more active than T-DM1 against HER2/neu 3+ EOC xenografts.

Conclusions: SYD985 is a novel ADC with remarkable activity against EOC with strong (3+) as well as moderate to low (i.e., 2+ and 1+) HER2/neu expression. SYD985 is more potent than T-DM1 in comparative experiments and unlike T-DM1, it is active against EOC demonstrating moderate/low or heterogeneous HER2/neu expression.

Trial registration: ClinicalTrials.gov NCT02277717.

Keywords: Ado-trastuzumab emtansine; Antibody-drug conjugate; HER2; Ovarian serous carcinoma; SYD985; T-DM1.

MeSH terms

  • Ado-Trastuzumab Emtansine
  • Adult
  • Aged
  • Animals
  • Antibodies, Monoclonal, Humanized / pharmacology
  • Antibody-Dependent Cell Cytotoxicity
  • Antineoplastic Agents, Alkylating / administration & dosage
  • Bystander Effect / immunology
  • Carcinoma, Ovarian Epithelial
  • Cell Line, Tumor
  • Duocarmycins
  • Female
  • Humans
  • Immunotoxins / immunology
  • Immunotoxins / pharmacology*
  • Indoles / administration & dosage*
  • Maytansine / analogs & derivatives
  • Maytansine / pharmacology
  • Mice
  • Mice, SCID
  • Middle Aged
  • Neoplasms, Glandular and Epithelial / drug therapy*
  • Neoplasms, Glandular and Epithelial / enzymology
  • Neoplasms, Glandular and Epithelial / immunology
  • Ovarian Neoplasms / drug therapy*
  • Ovarian Neoplasms / enzymology
  • Ovarian Neoplasms / immunology
  • Pyrrolidinones / administration & dosage
  • Random Allocation
  • Receptor, ErbB-2 / biosynthesis
  • Receptor, ErbB-2 / genetics
  • Receptor, ErbB-2 / immunology*
  • Trastuzumab
  • Xenograft Model Antitumor Assays

Substances

  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents, Alkylating
  • Duocarmycins
  • Immunotoxins
  • Indoles
  • Pyrrolidinones
  • Maytansine
  • ERBB2 protein, human
  • Receptor, ErbB-2
  • Trastuzumab
  • duocarmycin A
  • Ado-Trastuzumab Emtansine

Associated data

  • ClinicalTrials.gov/NCT02277717