XCL1 and neuroblastoma: So far, three different phase I trials have been performed in NB patients unresponsive to conventional treatments, by employing either autologous or allogeneic NB tumour cells engineered to produce IL-2, alone or in combination with lymphotactin (Brenner et al, 2000; Rousseau et al, 2003; Bowman et al, 2003).