A novel mycobacterial Hsp70-containing fusion protein targeting mesothelin augments antitumor immunity and prolongs survival in murine models of ovarian cancer and mesotheliomaReport as inadecuate

A novel mycobacterial Hsp70-containing fusion protein targeting mesothelin augments antitumor immunity and prolongs survival in murine models of ovarian cancer and mesothelioma - Download this document for free, or read online. Document in PDF available to download.

Journal of Hematology and Oncology

, 7:15

First Online: 24 February 2014Received: 29 September 2013Accepted: 02 February 2014DOI: 10.1186-1756-8722-7-15

Cite this article as: Yuan, J., Kashiwagi, S., Reeves, P. et al. J Hematol Oncol 2014 7: 15. doi:10.1186-1756-8722-7-15


BackgroundAlthough dendritic cell DC vaccines are considered to be promising treatments for advanced cancer, their production and administration is costly and labor-intensive. We developed a novel immunotherapeutic agent that links a single-chain antibody variable fragment scFv targeting mesothelin MSLN, which is overexpressed on ovarian cancer and mesothelioma cells, to Mycobacterium tuberculosis MTB heat shock protein 70 Hsp70, which is a potent immune activator that stimulates monocytes and DCs, enhances DC aggregation and maturation and improves cross-priming of T cells mediated by DCs.

MethodsBinding of this fusion protein with MSLN on the surface of tumor cells was measured by flow cytometry and fluorescence microscopy. The therapeutic efficacy of this fusion protein was evaluated in syngeneic and orthotopic mouse models of papillary ovarian cancer and malignant mesothelioma. Mice received 4 intraperitoneal i.p. treatments with experimental or control proteins post i.p. injection of tumor cells. Ascites-free and overall survival time was measured. For the investigation of anti-tumor T-cell responses, a time-matched study was performed. Splenocytes were stimulated with peptides, and IFNγ- or Granzyme B- generating CD3CD8 T cells were detected by flow cytometry. To examine the role of CD8 T cells in the antitumor effect, we performed in vivo CD8 cell depletion. We further determined if the fusion protein increases DC maturation and improves antigen presentation as well as cross-presentation by DCs.

ResultsWe demonstrated in vitro that the scFvMTBHsp70 fusion protein bound to the tumor cells used in this study through the interaction of scFv with MSLN on the surface of these cells, and induced maturation of bone marrow-derived DCs. Use of this bifunctional fusion protein in both mouse models significantly enhanced survival and slowed tumor growth while augmenting tumor-specific CD8 T-cell dependent immune responses. We also demonstrated in vitro and in vivo that the fusion protein enhanced antigen presentation and cross-presentation by targeting tumor antigens towards DCs.

ConclusionsThis new cancer immunotherapy has the potential to be cost-effective and broadly applicable to tumors that overexpress mesothelin.

KeywordsMycobacterial Hsp70 Mesothelin Single chain variable fragment Cancer immunotherapy Murine tumor model AbbreviationsDCDendritic cell

scFvSingle-chain antibody variable fragment


MTBMycobacterium tuberculosis

HspHeat shock protein



BMDCsBone marrow-derived dendritic cells

APCsAntigen-presenting cells

PBMCsPeripheral blood mononuclear cells

PBLsPeripheral blood leukocytes


HandEHaematoxylin and eosin



mAbmonoclonal antibody.

Electronic supplementary materialThe online version of this article doi:10.1186-1756-8722-7-15 contains supplementary material, which is available to authorized users.

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Author: Jianping Yuan - Satoshi Kashiwagi - Patrick Reeves - Jean Nezivar - Yuan Yang - Nadiah Hashim Arrifin - Mai Nguyen - Gilbe

Source: https://link.springer.com/

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