In the phase I trial for solid tumor patients, weekly administration of KRN7000 did not allow sufficient time for NKT cell recovery. As KRN7000 is reported to be an activating ligand for NKT cells, it is logical to assume that a dosing interval that provides time for recovery of NKT cells is optimal. In fact, cytokine production after repeating dosing, when NKT cells were hardly detected in the peripheral blood, was not observed. As it took approximately 4 weeks for NKT cells to recover to pre-dose levels after a single administration, monthly administration is now proposed for this trial.