Antibody conjugates of 7-ethyl-10-hydroxycamptothecin (SN-38) for targeted cancer chemotherapy

J Med Chem. 2008 Nov 13;51(21):6916-26. doi: 10.1021/jm800719t. Epub 2008 Oct 22.


CPT-11 is a clinically used cancer drug, and it is a prodrug of the potent topoisomerase I inhibitor, SN-38 (7-ethyl-10-hydroxycamptothecin). To bypass the need for the in vivo conversion of CPT-11 and increase the therapeutic index, bifunctional derivatives of SN-38 were prepared for use in antibody-based targeted therapy of cancer. The general synthetic scheme incorporated an acetylene-azide click cycloaddition step in the design, a short polyethylene glycol spacer for aqueous solubility, and a maleimide group for conjugation. Conjugates of a humanized anti-CEACAM5 monoclonal antibody, hMN-14, prepared using these SN-38 derivatives were evaluated in vitro for stability in buffer and human serum and for antigen-binding and cytotoxicity in a human colon adenocarcinoma cell line. Conjugates of hMN-14 and SN-38 derivatives 16 and 17 were found promising for further development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylene / chemistry
  • Antibodies / chemistry*
  • Antibodies / immunology*
  • Antineoplastic Agents / chemical synthesis*
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / immunology
  • Antineoplastic Agents / pharmacology*
  • Azides / chemistry
  • Camptothecin / analogs & derivatives*
  • Camptothecin / chemical synthesis
  • Camptothecin / chemistry
  • Camptothecin / pharmacology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Humans
  • Irinotecan
  • Kinetics
  • Molecular Structure
  • Structure-Activity Relationship


  • Antibodies
  • Antineoplastic Agents
  • Azides
  • Irinotecan
  • Acetylene
  • Camptothecin