A high level of evidence supports that [tumor-infiltrating lymphocytes] are prognostic. Some people are suggesting that they can now be incorporated into treatment decision-making, as we do with other routine prognostic factors such as estrogen receptor status and Ki67.— Melinda L. Telli, MD
Melinda L. Telli, MD, Assistant Professor of Medicine at Stanford University Medical Center, Palo Alto, commented on this topic for The ASCO Post. She said the results of the two studies reinforce what has been emerging about the prognostic impact of tumor-infiltrating lymphocytes.
“We have known that in the primary breast cancer setting, tumor-infiltrating lymphocyte levels are definitely prognostic, and they are predictive of chemotherapy benefit, especially in HER2-positive and triple-negative breast cancers. Now we have heard that they are prognostic even in the metastatic setting,” she said. “In the metastatic setting, you typically have fewer [tumor-infiltrating lymphocytes], but if you do have them, they are a positive prognostic factor. Here, they are more related to prognosis than to prediction.”
In the German study, tumor-infiltrating lymphocytes were found to be prognostic in all subtypes, including luminal breast cancer, she noted, adding that the size of the study population—more than 3,000 patients—lends credence to the findings.
The next question is how to use this information, Dr. Telli continued. “A high level of evidence supports that [tumor-infiltrating lymphocytes] are prognostic. Some people are suggesting that they can now be incorporated into treatment decision-making, as we do with other routine prognostic factors such as estrogen receptor status and Ki67.”
But Dr. Telli suggested their role will be greater in the future, “as we move into the realm of immunotherapies.” There, she said, tumor-infiltrating lymphocytes “can give us a sense of whether a tumor has innate antitumor immunity, and that may help us in designing strategies for immunotherapy…. They may have a greater therapeutic impact as we move into this area, where the next wave will be to look at adding checkpoint inhibitors.” ■
Disclosure: Dr. Telli reported no potential conflicts of interest.