The following article features coverage from the European Society of Medical Oncology (ESMO) 2017 Congress in Madrid, Spain. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Patients with metastatic triple-negative breast cancer (mTNBC) likely to respond to pembrolizumab monotherapy may be identified by high levels of tumor infiltrating lymphocytes (TIL), according to data presented at the European Society of Medical Oncology (ESMO) 2017 Congress in Spain.1

For this study, researchers analyzed data from the KEYNOTE-086 phase 2 study ( Identifier: NCT02447003), in which patients with mTNBC received pembrolizumab monotherapy regardless of PD-L1 expression (cohort A) or when determined to be PD-L1-positive (cohort B). Response to therapy was evaluated every 9 weeks for 1 year and every 3 months thereafter.

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Of the 222 enrolled patients, 193 had evaluable tumor samples; 146 samples were collected from metastatic sites and 47 were collected from primary breast cancer tumors. Higher median TIL levels were observed in cohort B compared with cohort A (17.5% [6.2% -57.5%] vs 5% [1%-10%]; Wilcoxon rank sum P < .001), and in lymph node compared with non-lymph node samples (10% [5%-50%] vs 5% [2%-15%]; P = .01).

The overall response rate (ORR) in patients with greater than median TIL levels was 6% vs 2% in patients who had less than median TIL levels in cohort A, and was 39% vs 9% in cohort B. The median TIL levels in responders and non-responders were 10% (7.5%-25%) and 5% (1-10%), respectively, in cohort A, and 50% (5%-70%) and 15% (5%-37.5%), respectively, in cohort B.

In the combined cohorts, a significantly improved ORR (odds ratio 1.26; 95% CI, 1.03-1.55; P = .01) and disease control rate (odds ratio 1.22; 95% CI, 1.02-1.46; P = .01) was observed in patients with higher TIL levels.

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The results of the study demonstrate that increased TIL levels may be associated with a greater response to pembrolizumab monotherapy in patients with mTNBC, especially in the first-line setting.

Read more of Cancer Therapy Advisor‘s coverage of the European Society of Medical Oncology (ESMO) 2017 Congress by visiting the conference page.


  1. Loi S, Adams S, Schmid P, et al. Relationship between tumor infiltrating lymphocyte (TIL) levels and response to pembrolizumab (pembro) in metastatic triple-negative breast cancer (mTNBC): results from KEYNOTE-086. Presented at: European Society of Medical Oncology (ESMO) 2017 Congress; Madrid, Spain: September 8-12, 2017. Abstract LBA13.