title: Intratumoral IL-12 and TNF-alpha-loaded microspheres lead to regression of breast cancer and systemic antitumor immunity.
abstract: BACKGROUND
  Local, sustained delivery of cytokines at a tumor can enhance induction of antitumor immunity and may be a feasible neoadjuvant immunotherapy for breast cancer. We evaluated the ability of intratumoral poly-lactic-acid-encapsulated microspheres (PLAM) containing interleukin 12 (IL-12), tumor necrosis factor alpha (TNF-alpha), and granulocyte-macrophage colony stimulating factor (GM-CSF) in a murine model of breast cancer to generate a specific antitumor response.
  
  
  METHODS
  BALB/c mice with established MT-901 tumors underwent resection or treatment with a single intratumoral injection of PLAM containing IL-12, TNF-alpha, or GM-CSF, alone or in combination. Two weeks later, lymph nodes and spleens were harvested, activated with anti-CD3 monoclonal antibodies (mAb) and rhIL-2, and assessed for antitumor reactivity by an interferon gamma (IFNgamma) release assay. Tumor-infiltrating lymphocyte (TIL) analysis was performed on days 2 and 5 after treatment by mechanically processing the tumors to create a single cell suspension, followed by three-color fluorescence-activated cell sorter (FACS) analysis.
  
  
  RESULTS
  Intratumoral injection of cytokine-loaded PLAM significantly suppressed tumor growth, with the combination of IL-12 and TNF-alpha leading to increased infiltration by polymorphonuclear cells and CD8+ T-cells in comparison with controls. The induction of tumor-specific reactive T-cells in the nodes and spleens, as measured by IFN-gamma production, was highest with IL-12 and TNF-alpha. This treatment resulted in resistance to tumor rechallenge.
  
  
  CONCLUSIONS
  A single intratumoral injection of IL-12 and TNF-alpha-loaded PLAM into a breast tumor leads to infiltration by polymorphonuclear cells and CD8+ T-cells with subsequent tumor regression. In addition, this local therapy induces specific antitumor T-cells in the lymph nodes and spleens, resulting in memory immune response.
authors.affiliation: Division of Surgical Oncology, University of Michigan, Ann Arbor, Michigan, USA. msabel@umich.edu
authors.forename: Michael S
authors.initials: MS
authors.lastname: Sabel
authors.forename: Joseph
authors.initials: J
authors.lastname: Skitzki
authors.forename: Lloyd
authors.initials: L
authors.lastname: Stoolman
authors.forename: Nejat K
authors.initials: NK
authors.lastname: Egilmez
authors.forename: Edith
authors.initials: E
authors.lastname: Mathiowitz
authors.forename: Nicola
authors.initials: N
authors.lastname: Bailey
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Chang
authors.forename: Alfred E
authors.initials: AE
authors.lastname: Chang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000628:therapy*; D005260:Female; D007167:Immunotherapy / Q000379:methods*; D018664:Interleukin-12 / Q000008:administration & dosage*; D051379:Mice; D008807:Mice, Inbred BALB C; D008863:Microspheres; D020360:Neoadjuvant Therapy; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage*
chemical_list: D000970:Antineoplastic Agents; D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12