Surgical cytoreduction restores the antitumor efficacy of a Listeria monocytogenes vaccine in malignant pleural mesothelioma

Gregory T. Kennedy, Brendan F. Judy, Pratik Bhojnagarwala, Edmund K. Moon, Zvi G. Fridlender, Steven M. Albelda, Sunil Singhal*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Recent studies suggest that immunotherapy may offer a promising treatment strategy for early-stage malignant pleural mesothelioma (MPM), but advanced tumor burden may limit the efficacy of immunotherapy. Therefore, we hypothesized that surgical cytoreduction could restore the efficacy of vaccine-based immunotherapy for MPM. We developed a murine model of MPM through transduction of a mesothelioma cell line with mesothelin. We used this model to evaluate the efficacy of a Listeria monocytogenes vaccine expressing mesothelin. Tumor growth was significantly inhibited at four weeks in animals vaccinated two weeks prior to tumor cell inoculation as compared to those given an empty vector control (1371±420mm3 versus 405±139mm3; p<0.01). Mice vaccinated one week prior to tumor challenge also displayed significant reduction in tumor volume (1227±406mm3 versus 309±173mm3; p<0.01). The vaccine had no effect when administered concurrently with tumor challenge, or after tumors were established. Flow cytometry showed reduced mesothelin expression in large tumors, as well as tumor-associated immunosuppression due to increased myeloid derived suppressor cells (MDSCs). These factors may have limited vaccine efficacy for advanced disease. Surgical cytoreduction of established tumors restored the antitumor potency of the therapeutic vaccine, with significantly reduced tumor burden at post-operative day 18 (397±103mm3 versus 1047±258mm3; p<0.01). We found that surgery reduced MDSCs to levels comparable to those in tumor-naïve mice. This study demonstrates that cytoreduction surgery restores the efficacy of cancer vaccines for MPM by reducing tumor-related immunosuppression that impairs immunotherapy.

Original languageAmerican English
Pages (from-to)28-35
Number of pages8
JournalImmunology Letters
Volume166
Issue number1
DOIs
StatePublished - 1 Jul 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 European Federation of Immunological Societies.

Keywords

  • Malignant mesothelioma
  • Surgical cytoreduction
  • Vaccine immunotherapy

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