In contrast to our observations and those of Yan et al. in pancreatic and ampullary cancers, intratumoural HHLA2 expression levels were associated with increased risk of cancer recurrence or decreased survival in triple-negative breast cancer, renal cell carcinoma osteosarcoma, colorectal cancer and bladder urothelial carcinoma.19,20,22–24 One reason for these contrasting clinical associations may be related to different methods of scoring HHLA-2 expression. Here, HHLA2 is linked to triple-negative breast carcinoma.