NY‐ESO‐1 protein expression in primary breast carcinoma and metastases—correlation with CD8+ T‐cell and CD79a+ plasmacytic/B‐cell infiltration

Abstract NY‐ESO‐1 is a cancer testis antigen expressed in various malignancies and testicular germ cells. Because of its capacity to induce specific humoral and cellular immunity in patients with NY‐ESO‐1‐positive carcinomas, it represents a promising target for cancer immunotherapy. In breast cancer, NY‐ESO‐1‐mRNA was reported in up to 42%, but protein expression has not been determined to larger extent. In the present tissue microarray‐based study, primary breast cancers ( n = 1,444), in situ lesion ( n = 148), recurrences ( n = 88), lymph node ( n = 525) and distant metastases ( n = 91) were studied for NY‐ESO‐1 expression by immunohistochemistry. NY‐ESO‐1‐protein expression was compared with mRNA expression by real‐time PCR. NY‐ESO‐1‐protein was detected in 3.1% (4/128) in situ lesions and in 2.1% (28/1355) invasive breast cancer. There were 1.8% (9/493) NY‐ESO‐1‐positive lymph node and 5.1% (4/78) positive distant metastases. NY‐ESO‐1 was more frequently expressed in grade 3 (4.9%) than in grade 2 (0.8%) and grade 1 (0.5%) carcinomas ( p < 0.0001). Presence of tumor‐infiltrating CD8+ T‐cells correlated with NY‐ESO‐1 ( p < 0.0001) on the tissue microarray. On randomly selected large sections, 4 out of 9 NY‐ESO‐1‐positive tumors displayed a brisk infiltrate of CD79a+ plasmocytes/B‐cells, but none of 10 NY‐ESO‐1‐negative tumors ( p < 0.05). NY‐ESO‐1‐mRNA expression was detected in frozen samples of NY‐ESO‐1‐protein positive ( n = 6) and negative breast cancers ( n = 8) and in normal testis. Comparison between mRNA and protein expression revealed that only breast cancers with NY‐ESO‐1‐mRNA levels comparable or higher than testis expressed NY‐ESO‐1‐protein. These findings suggest that NY‐ESO‐1‐positive breast cancers represent a small subset of poorly differentiated tumors with evidence of cellular and humoral immune response. © 2007 Wiley‐Liss, Inc.