Generation of interleukin-2-secreting melanoma cell populations from resected metastatic tumors

This study aimed to determine the feasibility of producing patient-specific, interleukin-2 (IL-2)-secreting tumor cell vaccines for the treatment of metastatic melanoma. Primary tumor cell cultures were established from 26/33 resected metastatic melanoma samples. Recombinant retroviral gene transfer and expression in these cultures was optimized using an amphotropic, defective retrovirus carrying the LacZ gene. All cell cultures were infectable; those that proliferated more rapidly were infected at a higher frequency. Addition of fibroblast growth factor to the culture medium increased the rate of cell proliferation and the efficiency of infection. A single infection with an identical retrovirus carrying a human IL-2 cDNA resulted in the generation of unselected cell populations secreting up to 300 units IL-2/10(6) cells.48 hr. Multiple infections increased the level of IL-2 secretion to 5,000 units/10(6) cells.48 hr. The recombinant viral genome could be detected at approximately single copy in the multiply infected cells; no helper virus was detected. IL-2 secretion from infected cultures was maintained following cryopreservation and x-irradiation. These data demonstrate that heterogeneous tumor cell populations secreting IL-2 can be generated from individual patients to be used as autologous, irradiated cell vaccines.