Tumor-derived activated cells: preliminary laboratory and clinical results

It is well known that T lymphocytes can mediate significant anti-tumor responses. A limiting factor has always been the ability to expand T cells, whether from the peripheral blood, spleen, or tumor. The recent availability of recombinant interleukin-2 (r-IL2) has demonstrated the feasibility of expanding T cells and the clinical efficacy of these cells as anti-tumor effectors in murine models. Concomitantly, researchers discovered that lymphokine-activated killer cells--peripheral blood cells functionally distinct from T cells--could be cultured, expanded, and re-infused in patients, with significant clinical effects. For many years, the infiltrating lymphocytes have been recognized in tumor biopsies and known to be cytolytically active. Major limiting factors were the ability to culture large numbers of these infiltrating cells and the limited understanding of the tumor antigens involved for T-cell stimulation. Restimulation by antigen (tumor cells) appears to provide the ongoing antigen stimulation needed to maintain selective killing of tumor cells. By defining various factors in the medium that support and enhance T-cell growth and activation, the components are becoming available to develop a broad attack on advanced cancer by using this laboratory-based technology of stimulation and expansion of tumor-derived activated cells.