No abstract

Tumor recurrence from residual local or micro-metastatic disease remains a problem in cancer therapy. In patients with soft-tissue sarcoma and patients with inoperable non-small cell lung cancer, local recurrence is common and significant mortality is caused by the subsequent emergence of metastatic disease. Thus, while the aim of the primary therapy is curative, the outcome may be improved by additional targeting of residual microscopic disease. We demonstrate in a murine model that surgical removal of a large primary sarcoma results in local recurrence in approximately 50% of animals. Depletion of CD8 T cells results in local recurrence in 100% of animals, indicating that these cells are involved in control of residual disease. We further demonstrate that systemic adjuvant administration of αOX40 at surgery eliminates local recurrences. In this model, αOX40 acts to directly enhance tumor antigen-specific CD8 T cell proliferation in the lymph node draining the surgical site, and results in increased tumor antigen-specific cytotoxicity in vivo. These results are also corroborated in a murine model of hypofractionated radiation therapy of lung cancer. Administration of αOX40 in combination with radiation significantly extended survival compared to either agent alone, and resulted in a significant proportion of long-term tumor free survivors. We conclude that αOX40 increases tumor antigen-specific CD8 T cell cytotoxic activity resulting in improved endogenous immune control of residual microscopic disease, and we propose that adjuvant αOX40 administration may be a valuable addition to surgical and radiation therapy for cancer.

No abstract

In this report, we evaluated the efficacy of a GM-CSF-producing tumor vaccine given before and after docetaxel in mice bearing established lung tumors. Mice bearing established 3LL tumors were treated with docetaxel and tumor vaccines transduced with either control or GM-CSF adenoviral vectors. Docetaxel (5-20 mg/kg) treatment alone had only a minimal effect on growth of established 3LL tumors in vivo, although docetaxel was cytotoxic to 3LL cells in vitro. When mice bearing established 3LL tumors were pretreated with docetaxel followed by vaccination with irradiated GM-CSF- transduced 3LL tumor cells, significant tumor regression and prolonged survival were observed compared with chemotherapy alone. Delaying docetaxel treatment until after tumor vaccination abrogated the vaccine's anti-tumor effects. Mice that survived treatment were able to resist a lethal rechallenge of 3LL tumor cells. Memory CTL specific for an epitope (MUT-1) derived from 3LL were detected in surviving mice. Docetaxel induced a mild lymphodepletion in mice, both CD4 and CD8 subsets were reduced in LN and spleens. Interestingly, docetaxel also diminished the number of memory CD8+ T cells (CD122+) and possible CD4+ CD25+ Foxp3+ natural Treg cells. Docetaxel treatment did not affect antigen-driven proliferation of naive T cells but significantly promoted survival of activated T cells. Thus, augmentation of vaccine induced antitumor immunity in docetaxel-treated mice primarily due to the enhanced survival of antigen-experienced T cells.