Prevention of lethal tumor growth and generation of long-lasting immunity in vivo using CD137L and interleukin-12 gene transfer.

: In a wide range of solid tumors, overexpression of CD137L has been shown to induce tumor immunity partly due to the stimulation of CD8+ CTL, which was even increased when immunotherapy with interleukin-12 (IL12) was additionally employed. However, little in known regarding hematologic neoplasias in this respect. Of the 8 animals receiving IL12-secreting tumor cells, 2 died. Animals treated with CD137L-expressing tumor cells and the combination group, all animals survived. Interestingly, re-challenge with wild-type tumor cells was rejected by all animals in the CD137L group and all remaining animals in the IL12 group, while these in the control group died. IL12- and CD137L-transfected plasmocytoma cells prevented tumor growth and induced long-lasting immunity. Our results warrant follow-up for future clinical use in patients with myeloma.