This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kudo-Saito, C. Articles by Hodge, J. W. Search for Related Content PubMed PubMed Citation Articles by Kudo-Saito, C. Articles by Hodge, J. W.

Combination Therapy of an Orthotopic Renal Cell Carcinoma Model Using Intratumoral Vector-Mediated Costimulation and Systemic Interleukin-2

Authors' Affiliations: Laboratories of ¹ Tumor Immunology and Biology and ² Experimental Immunology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland

Requests for reprints: Jeffrey Schlom, Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, NIH, 10 Center Drive, Room 8B09, Bethesda, MD 20892. Phone: 301-496-4343; Fax: 301-496-2756; E-mail: js141c{at}nih.gov.

Purpose: Interleukin (IL)-2 therapy is currently used for therapy of renal cell carcinoma (RCC). However, it is only effective in approximately 10% to 15% of patients, showing a need for additional therapies. We have previously described a replication-defective fowlpox vector encoding three costimulatory molecules (B7-1, ICAM-1, and LFA-3), designated rF-TRICOM. Here, we show that intratumoral administration of rF-TRICOM in an orthotopic RCC model effectively enhances tumor immunogenicity and reduces tumor burden in mice and the combination of rF-TRICOM and IL-2 is more effective than either therapy alone.

Experimental Design: RCC cells were implanted under the capsule of the kidney, and mice were given rF-TRICOM intratumorally 14 days later. We compared the effect of rF-TRICOM, rF-granulocyte macrophage colony-stimulating factor (GM-CSF), and two doses of IL-2 and combinations of the above on antitumor efficacy and survival. Host CD4⁺ and CD8⁺ T-cell responses were also evaluated.

Results: The results show that (a) systemic IL-2 therapy was moderately effective in the reduction of tumor burden in an orthotopic RCC model; (b) a single intratumoral injection of rF-TRICOM and rF-GM-CSF significantly reduced tumor burden; (c) the addition of systemic IL-2 to intratumoral rF-TRICOM/rF-GM-CSF administration resulted in further reduction of tumor burden, decrease in the incidence of metastasis, and extended survival in tumor-bearing mice above that seen with either treatment alone; and (d) CD8⁺ T cells played a critical role in the antitumor effect seen with rF-TRICOM/rF-GM-CSF + IL-2 therapy. Finally, the addition of systemic recombinant IL-15 or intratumoral vector-delivered IL-15 to intratumoral rF-TRICOM/rF-GM-CSF administration resulted in substantially more tumor-free mice than either therapy alone.

Conclusions: These studies show that intratumoral administration of rF-TRICOM admixed with rF-GM-CSF is effective at reducing tumor burden in mice and the addition of IL-2 further contributes to this effect. These studies thus form the rationale for combination immunotherapy clinical trials in patients with RCC.