Unsurprisingly, elevated levels of CTLA-4 in association with poor prognosis has been found in NSCLC [49–51], breast cancer [52, 53], nasopharyngeal carcinoma [54], small cell lung cancer (SCLC) [55], prostate cancer [56], thymoma [57], melanoma [58, 59], colorectal cancer (CRC) [60], glioblastoma [61] and osteosarcoma [62]. Here, CTLA4 is linked to small cell lung carcinoma.