Polymalic acid nanobioconjugate for simultaneous inhibition of tumor growth and immunostimulation in HER2/neu-positive breast cancer✩

Breast cancer remains the second leading cause of cancer death among women in the United States. The breast cancer prognosis is particularly poor in case of tumors overexpressing the oncoprotein HER2/neu. A new nanobioconjugate of the Polycefin family of anti-cancer drugs based on biodegradable and non-toxic polymalic acid (PMLA) was engineered for a multipronged attack on HER2/neu-positive breast cancer cells. An antibody cytokine fusion protein consisting of the immunostimulatory cytokine interleukin-2 (IL-2) genetically fused to an antibody specific for human HER2/neu [anti-HER2/neu IgG3-(IL-2)] was covalently attached to the PMLA backbone to target HER2/neu expressing tumors and ensuring the delivery of IL-2 to the tumor microenvironment. Antisense oligonucleotides (AON) were conjugated to the nanodrug to inhibit the expression of vascular tumor protein laminin-411 in order to block tumor angiogenesis. It is shown that the nanobioconjugate was capable of specifically binding human HER2/neu and retaining the biological activity of IL-2. We also showed the uptake of the nanobioconjugate by HER2/neu-positive breast cancer cells and enhanced tumor targeting in vivo. In addition, the nanobioconjugate was capable of eliciting anti-tumor activity in immunocompetent mice bearing ✩This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. © 2013 The Authors. Published by Elsevier B.V. All rights reserved *Correspondence to: M.L. Penichet, Division of Surgical Oncology, Department of Surgery, University of California at Los Angeles (UCLA), 10833 Le Conte Avenue, CHS 54-140, Box 951782, Los Angeles, 90095-1782, USA. Tel. : +1 310 825 1304; fax: +1 310 825 7575. penichet@mednet.ucla. edu (M.L. Penichet). **Correspondence to: J.Y. Ljubimova, Department of Neurosurgery, CedarsSinai Medical Center, 8631 West Third Street, Suite 800E, Los Angeles, 90048, USA. Tel. : +1 310 423 0834; fax: +1 310 423 0810. ljubimovaj@cshs.org (J.Y. Ljubimova). 1Both authors contributed equally to this report. 2Present address: School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina. 3Present address: Unit of Investigative Research on Oncological Disease, Children's Hospital of Mexico “Federico Gomez”, Mexico City, Mexico. 4Present address: Department of Trauma Surgery, School of Medicine, Saga University, Japan. NIH Public Access Author Manuscript J Control Release. Author manuscript; available in PMC 2014 April 01. Published in final edited form as: J Control Release. 2013 November 10; 171(3): 322–329. doi:10.1016/j.jconrel. 2013.06. 001. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript D2F2/E2 murine mammary tumors that express human HER2/neu. Both IgG1 and IgG2a levels were significantly increased in animals treated with the PMLA-fusion nanobioconjugate compared to animals treated with the antibody–cytokine fusion protein alone or control animals, indicative of the induction of a humoral (TH2) and cell-mediated (TH1) immune responses. Animal survival in vivo was significantly longer after treatment with leading nanobioconjugate with fusion [antiHER2/neu IgG3-(IL-2)] antibody, p < 0.05. The combination of these molecules on a single polymeric platform is expected to act through direct elimination of cancer cells, inhibition of tumor angiogenesis, and orchestration of a potent immune response against tumor.