Are immune signatures a worthwhile tool for decision making in early-stage human epidermal growth factor receptor 2-positive breast cancer?

Clonality, Antigen Recognition, and Suppression of CD8+ T Cells Differentially Affect Prognosis of Breast Cancer Subtypes

PURPOSE

In breast cancer, response rates to immune therapies are generally low and differ significantly across molecular subtypes, urging a better understanding of immunogenicity and immune evasion.

EXPERIMENTAL DESIGN

We interrogated large gene-expression data sets including 867 node-negative, treatment-naïve breast cancer patients (microarray data) and 347 breast cancer patients (whole-genome sequencing and transcriptome data) according to parameters of T cells as well as immune microenvironment in relation to patient survival.

RESULTS

We developed a 109-immune gene signature that captures abundance of CD8 tumor-infiltrating lymphocytes (TIL) and is prognostic in basal-like, her2, and luminal B breast cancer, but not in luminal A or normal-like breast cancer. Basal-like and her2 are characterized by highest CD8 TIL abundance, highest T-cell clonality, highest frequencies of memory T cells, and highest antigenicity, yet only the former shows highest expression level of immune and metabolic checkpoints and highest frequency of myeloid suppressor cells. Also, luminal B shows a high antigenicity and T-cell clonality, yet a low abundance of CD8 TILs. In contrast, luminal A and normal-like both show a low antigenicity, and notably, a low and high abundance of CD8 TILs, respectively, which associates with T-cell influx parameters, such as expression of adhesion molecules.

CONCLUSIONS

Collectively, our data argue that not only CD8 T-cell presence itself, but rather T-cell clonality, T-cell subset distribution, coinhibition, and antigen presentation reflect occurrence of a CD8 T-cell response in breast cancer subtypes, which have been aborted by distinct T-cell-suppressive mechanisms, providing a rationale for subtype-specific combination immune therapies.

Role of Cytotoxic Tumor-Infiltrating Lymphocytes in Predicting Outcomes in Metastatic HER2-Positive Breast Cancer: A Secondary Analysis of a Randomized Clinical Trial

Importance

Accumulating evidence indicates that tumor-infiltrating lymphocytes (TILs) are associated with clinical outcomes and may predict the efficacy of chemotherapy and human epidermal growth factor receptor 2 (HER2, encoded by the gene ERBB2)-targeted therapy in patients with HER2-positive breast cancer.

Objective

To investigate the role of TILs, particularly cytotoxic CD8+ T cells, in the prediction of outcomes in patients with HER2-positive metastatic breast cancer randomized to an antibody-based (trastuzumab) vs a small molecule-based (lapatinib) anti-HER2 therapy.

Design, Setting, and Participants

The Canadian Cancer Trials Group MA.31 phase 3 clinical trial accrued patients from 21 countries and randomized 652 with HER2-positive metastatic breast cancer to receive trastuzumab or lapatinib, in combination with a taxane, from January 17, 2008, through December 1, 2011. Patients had received no prior chemotherapy or HER2-targeted therapy in the metastatic setting. The median follow-up was 21.5 months (interquartile range, 14.3-31.0). The tumor tissue collected for primary diagnosis was used in this ad hoc substudy. Sections were scored for TILs on hematoxylin-eosin (H&E)-stained sections, and immunohistochemical analysis was performed to assess CD8, FOXP3, CD56, and programmed cell death protein 1 (PD-1) expression on stromal (sTILs) and intratumoral TILs. Data were analyzed from July 15, 2015, through July 27, 2016.

Interventions

Treatment with trastuzumab or lapatinib in combination with taxane chemotherapy (paclitaxel or docetaxel) for 24 weeks.

Main Outcomes and Measures

Prognostic effects of biomarkers were evaluated for progression-free survival by stratified univariate log-rank test with Kaplan-Meier curves and by multivariate Cox proportional hazards regression; predictive effects were examined with a test of interaction between treatment allocation and biomarker classification.

Results

Of the 647 treated women (mean [SD] age, 55.0 [10.8] years), 614 had tumor tissue samples scored for H&E sTILs and 427 for CD8 biomarker assessments. Overall H&E sTIL counts of greater than 5% (high) were present in 215 cases (35%) but did not show significant prognostic or predictive effects. Univariate stratified analyses detected a significant predictive effect on risk for progression with lapatinib compared with trastuzumab among patients with low CD8+ sTIL counts (observed hazard ratio, 2.94; 95% CI, 1.40-6.17; P = .003) and among those with high CD8+ sTIL counts (observed hazard ratio, 1.36; 95% CI, 1.05-1.75; P = .02), confirmed in stepwise multivariate analysis (interaction P = .04). Other immunohistochemistry biomarkers were not associated with prognostic or predictive effects.

Conclusions and Relevance

In this secondary analysis of a phase 3 randomized clinical trial, a low level of preexisting cytotoxic sTILs predicted the most benefit from an antibody- vs a small molecule-based drug against the same target.

Trial Registration

clinicaltrials.gov Identifier: NCT00667251.

A Therapeutic Her2/neu Vaccine Targeting Dendritic Cells Preferentially Inhibits the Growth of Low Her2/neu-Expressing Tumor in HLA-A2 Transgenic Mice

PURPOSE

E75, a peptide derived from the Her2/neu protein, is the most clinically advanced vaccine approach against breast cancer. In this study, we aimed to optimize the E75 vaccine using a delivery vector targeting dendritic cells, the B-subunit of Shiga toxin (STxB), and to assess the role of various parameters (Her2/neu expression, combination with trastuzumab) in the efficacy of this cancer vaccine in a relevant preclinical model.

EXPERIMENTAL DESIGN

We compared the differential ability of the free E75 peptide or the STxB-E75 vaccine to elicit CD8(+) T cells, and the impact of the vaccine on murine HLA-A2 tumors expressing low or high levels of Her2/neu.

RESULTS

STxB-E75 synergized with granulocyte macrophage colony-stimulating factors and CpG and proved to be more efficient than the free E75 peptide in the induction of multifunctional and high-avidity E75-specific anti-CD8(+) T cells resulting in a potent tumor protection in HLA-A2 transgenic mice. High expression of HER2/neu inhibited the expression of HLA-class I molecules, leading to a poor recognition of human or murine tumors by E75-specific cytotoxic CD8(+) T cells. In line with these results, STxB-E75 preferentially inhibited the growth of HLA-A2 tumors expressing low levels of Her2/neu. Coadministration of anti-Her2/neu mAb potentiated this effect.

CONCLUSIONS

STxB-E75 vaccine is a potent candidate to be tested in patients with low Her2/neu-expressing tumors. It could also be indicated in patients expressing high levels of Her2/neu and low intratumoral T-cell infiltration to boost the recruitment of T cells-a key parameter in the efficacy of anti-Her2/neu mAb therapy. Clin Cancer Res; 22(16); 4133-44. ©2016 AACR.