Immunologic and biologic properties of the primary tumor during prolonged neoadjuvant chemoimmunotherapy

Patients with locally advanced cancers have a poor prognosis when treated with radiotherapy and/or surgery alone. The appearance of distant metastases shortly after removal of the primary tumor indicates that micrometastases are already present at the time of diagnosis. We observed a favorable outcome in patients with locally advanced breast cancer treated with a prolonged regimen of neoadjuvant chemotherapy plus granulocyte-macrophage colony-stimulating factor (GM-CSF[Leukine]) compared with patients receiving fewer chemotherapy cycles prior to surgery and radiotherapy. These results can partly be explained by the dose-intensive regimen used, but biologic and immunologic processes inherent to the prolonged presence of the primary tumor and its draining lymph nodes might also contribute to the beneficial outcome. The effects of the prolonged presence of the primary tumor during chemotherapy and GM-CSF administration on the antitumor immune response, and more specifically the functional properties of dendritic cells and T cells, are currently being investigated in a multicenter randomized clinical trial comparing prolonged neoadjuvant chemotherapy plus cytokines with a conventional treatment schedule. Aside from investigations concerning the immune system, other biologic processes, such as tumor angiogenesis, are being investigated at the same time.