CD274 and neoplasm: In order to investigate the mechanism of HPD, preimmunotherapy and postimmunotherapy tissues were subjected to next-generation sequencing in a College of American Pathologists-certified and Clinical Laboratory Improvement Amendment-accredited laboratory, respectively.18 Before immunotherapy, the tumor mutation burden (TMB) of the tumor tissue was 3.23, and PD-L1 expression was observed in less than 1% of tumor cells (PD-L1 negative).