Tumor reductive therapies and antitumor immunity.

Tumor reductive therapy is to reduce tumor burden through direct killing of tumor cells. So far, there is no report on the connection between antitumor immunity and tumor reductive therapies. In the last few years, a new category of cancer treatment, immunotherapy, emerged and they are categorized separately from classic cytotoxic treatments (chemo and radiation therapy).

In situ vaccine, immunological memory and cancer cure.

As surgery is able to remove primary tumors and limit metastases, the major challenge in cancer management is the prevention of post-resection recurrence and metastases. From the immune point of view, tumor resection removes the supply of tumor antigens that maintain an active concomitant antitumor immunity elicited by the primary tumor, and may also signal for deposition of immunological memory against future metastases. However, the natural course of this antitumor immunity in many cancer patients following complete tumor resection may not be favorable because protection is often lost after 1-3 years.

IL-12 augments antitumor responses to cycled chemotherapy.

Loss of antitumor response to repeated chemotherapy is a major cause of treatment failure in cancer patients. The development of acquired drug resistance is thought to come primarily from changes in tumor cells, and not host response to the tumor. Our recent study shows that antitumor immunity is activated and contributes significantly to the efficacy of chemotherapy.

Preexisting antitumor immunity augments the antitumor effects of chemotherapy.

Efficacy of cancer chemotherapy is generally believed to be the result of direct drug killing of tumor cells. However, increased tumor cell killing does not always lead to improved efficacy. Herein, we demonstrate that the status of antitumor immunity at the time of chemotherapy treatment is a critical factor affecting the therapeutic outcome in that tumor-bearing mice that possess preexisting antitumor immunity respond to chemotherapy much better than those that do not.

Lessons from Coley's Toxin.

The active molecule in Coley's Toxin is not tumor necrosis factor (TNF) or endotoxin (LPS), but interleukin-12 (IL-12). IL-12 holds the key to improved anti-tumor immuns response.

Inhibition of host signal transducer and activator of transcription factor 6 results in cure with cyclophosphamide and interleukin 12 immunotherapy.

Background: Interleukin (IL)-12 immunotherapy is highly effective against established immunogenic tumors. However, nonimmunogenic tumors fail to respond to IL-12 therapy. Analysis of tumor rejection of the immunogenic tumors shows that a preexisting antitumor immune response is required for an effective IL-12 response.

Antitumor immunity induced by dendritic cell-based vaccination is dependent on interferon-gamma and interleukin-12.

Background: This study was conducted to determine whether dendritic cells (DCs) pulsed with a tumor cell lysate can effectively vaccinate against tumor cells and to establish which cytokines are necessary.

Materials And Methods: Each wild-type mouse received two subcutaneous immunizations (days 14 and 7) with either saline, tumor lysate, DCs, or tumor-lysate-pulsed DCs. Gamma-interferon (gamma-IFN), knock-out (KO), and interleukin-12 (IL-12) KO mice were also used in immunizations.

Cure of an established nonimmunogenic tumor, SCC VII, with a novel interleukin 12-based immunotherapy regimen in C3H mice.

Objective: To develop a murine model of effective treatment with immunotherapy for established head and neck squamous cell carcinoma.

Design: Prospective animal study. Subjects Female C3H mice, 8 to 12 weeks old.

Production of interferon-gamma by tumor-sensitized T cells is essential for interleukin-12-induced complete tumor eradication.

Background: Interferon-gamma (IFN-gamma) is essential for eradication of established large tumors by interleukin-12 (IL-12), but the critical source of IFN-gamma has not been defined. Adoptive transfer of T cells into T cell-deficient mice allows for evaluation of the role of T cells and T cell production of IFN-gamma in the antitumor immune response.

Methods: Wild-type C57BL/6, IL-12 receptor-beta1 knockout (IL-12Rbeta1 KO), IFN-gamma knockout (IFN-gamma KO), and IFN-gamma receptor-alpha knockout (IFN-gammaRalpha KO) mice were immunized and used as donors for adoptive transfer.

The role of IFN-gamma in rejection of established tumors by IL-12 : source of production and target.

We have demonstrated previously that established small and large murine MCA207 sarcomas can be completely eradicated by treatment with interleukin (IL) 12 alone and cyclophosphamide plus IL-12 (Cy+IL-12), respectively. The antitumor effect of IL-12/Cy+IL-12 has been found to be dependent on IFN-gamma and T cells. The role of IFN-gamma in IL-12-induced tumor rejection is unclear, because after IL-12 administration IFN-gamma is produced by multiple cell types, and it acts on most cell types because of the ubiquitous expression of its receptor.