Tumor-infiltrating Lymphocytes Associated With HER2+ Breast Cancer Survival

Among patients with advanced HER2+ breast cancer, higher tumor-infiltrating lymphocyte (TIL) values in tumor stroma are associated with longer overall survival (OS), according to findings from a secondary analysis of the CLEOPATRA (ClinicalTrials.gov Identifier: NCT00567190) trial presented at the 2016 San Antonio Breast Cancer Symposium and published in The Lancet Oncology.^1,2

“The positive influence of pre-existing antitumor immunity persists in the advanced setting,” reported lead study author Stephen J. Luen, MBChB, of the Sherene L Peter MacCallum Cancer Centre, University of Melbourne, Australia. “Each 10% increase in stromal TILs was associated with an 11% reduction in the risk of death.”

CLEOPATRA participants were administered first-line docetaxel, trastuzumab, and either pertuzumab or placebo. The association between OS and TILs was linear and did not differ between treatment groups. “No predictive effect was observed with regard to pertuzumab treatment,” Dr Luen said.

“Tumor TILs are associated with improved pathological complete response rates as well as survival” in other settings, Dr Luen noted. But their association with outcomes in the setting of advanced HER2+ breast cancer has not been previously examined.

The new analysis was based on 678 CLEOPATRA participants for whom TIL data were evaluable; 23% of samples were freshly obtained (within 45 days of randomization) and 519 were archival.

The 3-year OS among patients who received pertuzumab and had stromal TILs exceeding 20% was 78%. There was a statistically-non-significant trend between higher TILs and improved progression-free survival.

Strategies to augment immunity in advanced breast cancer might further improve survival rates, Dr Luen said.

Reference

1. Luen SJ, Salgado R, Fox S, et al. Prognostic associations of tumor-infiltrating lymphocytes (TILs) in advanced HER2-positive breast cancer treated with pertuzumab and trastuzumab: a secondary analysis of the CLEOPATRA study. Paper presented at: 39^th San Antonio Breast Cancer Symposium; Dec 2016; San Antonio, TX.
2. Luen SJ, Salgado R, Fox S, et al. Tumour-infiltrating lymphocytes in advanced HER2-positive breast cancer treated with pertuzumab and trastuzumab: a retrospective analysis of the CLEOPATRA study. Lancet Oncol. 2016 Dec 7. doi: 10.1016/S1470-2045(16)30631-3 [Epub ahead of print]