HER-2 pulsed dendritic cell vaccine can eliminate HER-2 expression and impact ductal carcinoma in situ

Abstract

Background: HER-2/neu overexpression plays a critical role in breast cancer development, and its expression in ductal carcinoma in situ (DCIS) is associated with development of invasive breast cancer. A vaccine targeting HER-2/neu expression in DCIS may initiate immunity against invasive cancer. Methods: A HER-2/neu dendritic cell vaccine was administered to 27 patients with HER-2/neu-overexpressing DCIS. The HER-2/neu vaccine was administered before surgical resection, and pre- and postvaccination analysis was conducted to assess clinical results. Results: At surgery, 5 of 27 (18.5%) vaccinated subjects had no evidence of remaining disease, whereas among 22 subjects with residual DCIS, HER-2/neu expression was eradicated in 11 (50%). When comparing estrogen receptor (ER) neg with ER pos DCIS lesions, vaccination was more effective in hormone-independent DCIS. After vaccination, no residual DCIS was found in 40% of ER neg subjects compared with 5.9% in ER pos subjects. Sustained HER-2/neu expression was found in 10% of ER neg subjects compared with 47.1% in ER pos subjects (P =.04). Postvaccination phenotypes were significantly different between ER pos and ER neg subjects (P =.01), with 7 of 16 (43.8%) initially presenting with ER posHER-2/neu pos luminal B phenotype finishing with the ER posHER-2/neu neg luminal A phenotype, and 3 of 6 (50%) with the ER negHER-2/neu pos phenotype changing to the ER negHER-2/neu neg phenotype. Conclusions: Results suggest that vaccination against HER-2/neu is safe and well tolerated and induces decline and/or eradication of HER-2/neu expression. These findings warrant further exploration of HER-2/neu vaccination in estrogen-independent breast cancer and highlight the need to target additional tumor-associated antigens and pathways. © 2011 American Cancer Society.