Transduction of a cytokine gene into neoplastic cells elicits a strong infl
ammatory host reaction that impairs tumor growth, and a long-lasting immune
memory is established following their rejection. These findings have arous
ed great enthusiasm and expectations. Despite their enhanced immunogenicity
, however, the immune reaction provoked by repeated injections of these eng
ineered cells can do little more than inhibit the growth of initial tumors
and metastases and is only minimally effective against established forms. B
etter therapeutic activity is thus being sought by combining such cells wit
h tumor cells engineered with other genes.