SPDL1 and cancer: Interestingly, analyzing sera from additional cancer patients treated with anti-CTLA-4, anti-PD-1, or anti-PD-L1 mAbs in monotherapy, we showed that a significant increase of sPD-L1 was detected only in patients treated with anti-PD-L1 but not with anti-CTLA-4 or anti-PD-1 mAbs.