Modeling tumor regrowth and immunotherapy

Deterministic models describing mechanisms underlying tumor growth, suppression, and regrowth are proposed and fit to kinetic data on B cell lymphoma in mice. It is demonstrated that either a modest change in the effectiveness of killer cell suppression, or the existence of a variant nonimmunogenic clone of the tumor cells, can explain the regrowth of a tumor after initial suppression. Adjuvant immunotherapy after establishing the cancer dormancy is modeled as a stimulated increase of the flow of killer cells into the tumor or a local increase of the rate of proliferation of these cells in a tumor. We modeled the immunotherapy consisting of impulse injections of immune lymphocytes in the vicinity of the tumor. Our numerical experiments show that this immunotherapy does not completely destroy the tumor, although thereafter the tumor may persist in a dormant cancer state or have its regrowth markedly delayed.