High Levels of Immune Cells in HER2-Positive Cancers May Mean Tumors Need Only Chemotherapy

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Tumor-infiltrating lymphocytes are white blood cells that have left the bloodstream and moved into a cancer tumor. White blood cells are immune cells made by your bone marrow to help your body fight infection.

Researchers have wondered if cancer tumors that have higher levels of these immune system cells might respond differently to certain treatments than tumors with lower levels of the cells. So certain cancer patients might be able avoid certain treatments if they have higher levels of immune system cells in the cancer tumor.

A study suggests that HER2-positive breast cancer tumors with high levels of tumor-infiltrating lymphocytes had a lower risk of the cancer coming back (recurrence) when treated with chemotherapy alone compared to HER-positive tumors with low levels of tumor-infiltrating lymphocytes treated with only chemotherapy.

This means that HER2-positive breast cancers with high levels of tumor-infiltrating lymphocytes might be able to be treated with chemotherapy alone and avoid Herceptin (chemical name: trastuzumab).

The research was presented on Dec. 10, 2014 at the 2014 San Antonio Breast Cancer Symposium.

HER2-positive breast cancers have too many copies of the HER2/neu gene, which make too much of the HER2 protein. HER2-positive breast cancers tend to be aggressive, so doctors may recommend treatment with chemotherapy and/or Herceptin before or after surgery. Herceptin fights HER2-positive breast cancer by blocking the cancer cells’ ability to receive growth signals.

In the study, 945 women diagnosed with early-stage, HER2-positive breast cancer were randomly split into two groups for treatment after surgery:

  • one group got chemotherapy alone (489 women)
  • the other group got chemotherapy plus Herceptin (456 women)

The researchers measured the levels of tumor-infiltrating lymphocytes in each breast cancer. Tumors that were at least 60% infiltrated were considered to have high levels of tumor-infiltrating lymphocytes.

After about 4.4 years, the researchers looked at the recurrence rates among the women:

  • Women with high levels of tumor-infiltrating lymphocytes who were treated with chemotherapy alone had an 80% lower risk of recurrence compared to women with low levels of tumor-infiltrating lymphocytes who were treated with chemotherapy alone.
  • Women who were treated with chemotherapy plus Herceptin had the same recurrence rates no matter what their levels of tumor-infiltrating lymphocytes were.
  • Women who had high levels of tumor-infiltrating lymphocytes who were treated with chemotherapy alone had the same recurrence rates as the women treated with chemotherapy and Herceptin.

“These results suggest that levels of tumor-infiltrating immune cells may provide a biomarker to identify patients who might do well without trastuzumab, but we must conduct additional large clinical trials before we can consider changing clinical practice and omitting HER2-targeted therapy from the treatment regimens for patients who have high levels of tumor-infiltrating immune cells,” said Edith Perez, M.D., deputy director at large for the Mayo Clinic Cancer Center, who presented the study. Dr. Perez also is a member of the Breastcancer.org Professional Advisory Board.

In December 2013, Dr. Perez presented research at the 2013 San Antonio Breast Cancer Symposium that suggested that tumors with high levels of tumor-infiltrating lymphocytes might respond better to Herceptin.

“We were somewhat surprised by our finding that high levels of tumor-infiltrating immune cells were not associated with increased benefit among women receiving trastuzumab because a previous study had shown that this was the case,” said Dr. Perez. “However, the previous study had many fewer cases and lower statistical power.”

While researchers believe that tumor-infiltrating lymphocytes may kill some of the cells in a cancer tumor, as Dr. Perez said, more research is needed before doctors understand exactly how this process works and why some cancers have more tumor-infiltrating lymphocytes than others.

Stayed tuned to Breastcancer.org for the latest information on tumor-infiltrating lymphocytes and how they may affect breast cancer outcomes.

Read more news from the 2014 San Antonio Breast Cancer Symposium:



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