please check the link:PD-1 and Lieping Chen on CNN
http://www.cnn.com/video/?/video/international/2014/08/21/spc-vital-signs-immunotherapy-yale-cancer.cnn&iref=allsearch&video_referrer=http%3A%2F%2Fwww.cnn.com%2Fsearch%2F%3Fquery%3Dlieping%2520chen%26sortBy%3Drelevance