The PD-1/PD-L1 Axis in HER2+ Ductal Carcinoma In Situ (DCIS) of the Breast

Julianne M. Ubago, Luis Z. Blanco, Tiansheng Shen, Kalliopi P. Siziopikou

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


OBJECTIVES: The aims were to evaluate the programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) axis in ductal carcinoma in situ (DCIS) of the breast. METHODS: We reviewed 85 pure DCIS cases treated with surgical excision at our institution, including 51 luminal A (estrogen receptor [ER] positive/human epidermal growth factor 2 [HER2] negative), 15 luminal B (ER+/HER2+), 13 HER2 (ER-/HER2+), and six basal-like (ER-/HER2-/CK5/6+). The extent and intensity of PD-1 and PD-L1 immunohistochemical staining in the tumor-infiltrating lymphocytes (TILs) and in the tumor cells were recorded. RESULTS: Our study found that moderate/severe inflammation around DCIS correlated with HER2 expression (20/28 HER2+ cases [71%] vs 21/57 HER2- cases [37%], P = .005). Of interest, over half of the TILs around the HER2 subtype expressed PD-L1 (7/13, 54%). In addition, about one-third of TILs around the HER2 subtype expressed PD-1 (4/13, 31%). CONCLUSIONS: These findings suggest that immune-based therapeutic strategies may be used as a potential therapy in DCIS cases with PD-L1 overexpression, especially those of the HER2 molecular subtype.

Original languageEnglish (US)
Pages (from-to)169-176
Number of pages8
JournalAmerican journal of clinical pathology
Issue number2
StatePublished - Jul 5 2019


  • Ductal carcinoma in situ (DCIS)
  • HER2
  • PD-1 expression
  • PD-L1 expression
  • PD-L1 inhibitors
  • Tumor microenvironment

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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