Deep Sequencing of T-Cell Receptor DNA as a biomarker of clonally expanded TILs in breast cancer after immunotherapy.

Publication Type:

Journal Article

Source:

Cancer immunology research, Volume 4, Issue 10, p.835-844 (2016)

Abstract:

In early stage breast cancer, the degree of tumor-infiltrating lymphocytes (TILs) predicts response to chemotherapy and overall survival. Combination immunotherapy with immune checkpoint antibody plus tumor cryoablation can induce lymphocytic infiltrates and improve survival in mice. We used T-cell receptor (TCR) DNA sequencing to evaluate both the effect of cryo-immunotherapy in humans and the feasibility of TCR sequencing in early-stage breast cancer. In a pilot clinical trial, 18 women with early-stage breast cancer were treated pre-operatively with cryoablation, single-dose anti-CTLA-4 (ipilimumab), or cryoablation + ipilimumab. TCRs within serially collected peripheral blood and tumor tissue were sequenced. In baseline tumor tissues, T-cell density as measured by TCR sequencing correlated with TIL scores obtained by hematoxylin and eosin (H&E) staining. However, tumors with little or no lymphocytes by H&E contained up to 3.6 x 106 TCR DNA sequences, highlighting the sensitivity of the ImmunoSEQ platform. In this dataset, ipilimumab increased intratumoral T-cell density over time, whereas cryoablation {plus minus} ipilimumab diversified and remodeled the intratumoral T-cell clonal repertoire. Compared to monotherapy, cryoablation plus ipilimumab was associated with numerically greater numbers of peripheral blood and intratumoral T-cell clones expanding robustly following therapy. In conclusion, TCR sequencing correlates with H&E lymphocyte scoring, and provides additional information on clonal diversity. These findings support further study of the use of TCR sequencing as a biomarker for T cell responses to therapy and for the study of cryo-immunotherapy in early-stage breast cancer.