Interleukin-15 was tested to determine whether this recently discovered cytokine was capable of stimulating the growth of tumor derived activated T cells in culture (TDAC, also referred to as tumor infiltrating lymphocytes). When established cultures of IL-2 induced, IL-2 dependent TDAC were tested, IL-15 stimulated growth in a dose dependent manner, alone or in the presence of IL-2. One established TDAC was cultured with IL-15 alone for 18 passages over a 10 week period. Comparing IL-2 and IL-15 treated cultures, growth rate with IL-15 was slower. IL-15 doubled the secreted interferon alpha and granulocyte-macrophage colony stimulating factor. IL-15 and IL-2 were compared in primary TDAC cultures. IL-15 induced TDAC outgrowth in 3 of 6 cultures. IL-2 induced outgrowth in all 6. Tumor cells were eliminated as TDAC grew out in both IL-2 and IL-15 treated cultures. These results suggested that IL-15 like IL-2, is capable of stimulating the growth of TDAC with antitumor activity, but with certain distinct effects which may be of interest therapeutically.

This report describes the production of Tumor Derived Activated Cell cultures (TDAC, also called tumor infiltrating lymphocytes) from patient tumor biopsies and our preliminary experience growing these cells to therapeutic levels using artificial capillary bioreactor cultures. TDAC were successfully grown in medium containing Interleukin 2 from 80% of the 113 tumor biopsies tested. There was no significant difference in success (growth to 1 x 10(9) cells) comparing primary and metastatic tumors. Many of the tumors were shipped to the laboratory from distant sites. Success rate did decrease with the length of time for tumor transport. Interleukin 4 was beneficial in the development of 1 of 4 TDAC cultures which did not grow with IL-2 only. Seventy-seven bioreactor cultures were initiated for 31 patients. On the average, 1.9 x 10(9) TDAC were inoculated per bioreactor; 3.3 x 10(10) were harvested in 22 days. Twelve liters of medium were required per 1 x 10(10) TDAC produced. TDAC cultures contained T cells with variable ratios of CD4 to CD8 cells. Secreted granulocyte monocyte colony stimulating factor, interferon gamma and tumor necrosis factor were measured in the bioreactor cartridge conditioned medium. Twenty three patients were evaluated. Partial responses were observed in 4 patients including a dramatic remission of scalp nodules in a patient with renal cancer. Results showed that therapeutic amounts of TDAC cells may be produced in a reasonable and cost effective manner using artificial capillary bioreactor cultures.

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