Mutant isoforms of the KIT or PDGF receptors expressed by gastrointestinal stromal tumors (GISTs) are considered the therapeutic targets for STI571 (imatinib mesylate; Gleevec), a specific inhibitor of these tyrosine kinase receptors. Case reports of clinical efficacy of Gleevec in GISTs lacking the typical receptor mutations prompted a search for an alternate mode of action. Here we show that Gleevec can act on host DCs to promote NK cell activation. DC-mediated NK cell activation was triggered in vitro and in vivo by treatment of DCs with Gleevec as well as by a loss-of-function mutation of KIT. Therefore, tumors that are refractory to the antiproliferative effects of Gleevec in vitro responded to Gleevec in vivo in an NK cell–dependent manner. Longitudinal studies of Gleevec-treated GIST patients revealed a therapy-induced increase in IFN-γ production by NK cells, correlating with an enhanced antitumor response. These data point to a novel mode of antitumor action for Gleevec.
Christophe Borg, Magali Terme, Julien Taïeb, Cédric Ménard, Caroline Flament, Caroline Robert, Koji Maruyama, Hiro Wakasugi, Eric Angevin, Kris Thielemans, Axel Le Cesne, Véronique Chung-Scott, Vladimir Lazar, Isabelle Tchou, Florent Crépineau, François Lemoine, Jacky Bernard, Jonhantan A. Fletcher, Ali Turhan, Jean-Yves Blay, Alain Spatz, Jean-François Emile, Michael C. Heinrich, Salah Mécheri, Thomas Tursz, Laurence Zitvogel
