Women suffering from HER2-positive breast cancer that had high levels of immune cells in their tumors were found to have the most promising response to chemotherapy and trastuzumab before surgery.
"We have previously shown that high levels of [immune cells in a tumor] are predictive of response to trastuzumab and chemotherapy administered after surgery for early-stage, HER2-positive breast cancer using samples from patients enrolled on the randomized, adjuvant phase III clinical trial called the FinHER study," Sherene Loi, M.D., Ph.D., medical oncologist and head of the Translational Breast Cancer Genomics Lab at the Peter MacCallum Cancer Centre, said. "Our new data further support the positive relationship between tumor-infiltrating lymphocytes and better outcomes with trastuzumab therapy, this time in a cohort of patients with newly diagnosed HER2-positive breast cancer who received the therapy before surgery."
The research suggests tumor-infiltrating lymphocytes (the immune cells) could be an excellent indicator of how a patient will respond to trastuzumab therapy, an American Association for Cancer Research news release reported.
The researchers looked at HER2-positive breast tumor samples from 156 patients who received chemotherapy and trastuzumab therapies before surgery.
Women who receive both therapies have been shown to have the highest rate of recovery.
The team found that for every 10 percent increase in tumor immune cells there was a 16 percent increase in the number of patients that were found to have no residual signs of breast cancer.
"These data indicate that a patient's immune system influences outcome and trastuzumab response," Loi said. "What we don't know is why some patients have tumor-infiltrating lymphocytes in their breast tumor at diagnosis and others do not. Currently, we are actively investigating this and trying to understand why there is a positive relationship between tumor-infiltrating lymphocytes and better outcomes with trastuzumab therapy."
The team also looked at HER2-positive patients who either had trastuzumab or did not receive the treatment along with chemotherapy; they found trastuzumab "modulates the immune microenvironment, probably by relieving tumor-mediated immunosuppression through multiple immune-related factors, including one called PD-1."
In a study on rodents scientists also found that in HER2-positive breast cancer combining trastuzumab with a PD-1 suppressor resulted in higher rates of tumor regression.
"Thus, we suggest that adding an inhibitor that can block factors that suppress patient antitumor immune responses to trastuzumab therapy could potentially improve clinical outcomes," Loi said.
