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. Recent studies suggest that chemotherapy is able to activate this pre-existing antitumor immunity, and tumor resection following immune activation may lead to higher levels of immunological memory against future tumor antigens (in the form of metastases). Interleukin-12 added to chemotherapy mimics the function of a vaccine adjuvant in that it helps to enhance the antitumor immunity activated by chemotherapy and leaves a much stronger antitumor immune memory. This finding, when applied to cancer management, may help to maintain a strong and long lasting antitumor immunity following complete tumor resection, thus eliminating post-surgery recurrence and metastases.