White blood cell subsets in HER2-positive breast cancer patients treated with trastuzumab in relation to clinical outcome

Abstract

To examine whether HER2+ breast cancer patients who have decreased immune effector cells could respond well to trastuzumab, we evaluated the alterations in circulating immune system cell subsets: CD16+ and/or CD56+ lymphocytes, lymphocytes and granulocytes in these patients before and after treatment with trastuzumab-based regimens in relation to clinical response to therapy. The study involved 55 patients with HER2+ breast cancer before and 2 months after the initiation of the therapy. Progressive disease was confirmed in nine out of 55 patients (non-responders), while other patients achieved complete or partial response, or stable disease (responders). Control group consisted of up to 52 healthy individuals. Significantly lower percentages of total lymphocytes, CD16+, CD56+, and CD16+CD56+ lymphocytes as well as higher percentage of granulocytes and a higher ratio of granulocyte to lymphocyte percentages were found in patients before therapy and 2 months after the initiation of the therapy, compared with those in healthy individuals. Responder subgroup showed significantly lower percentages of CD16+, CD56+, and CD16+CD56+ lymphocytes before therapy, compared with those in healthy controls. Two months after the initiation of the therapy, the percentages of immune cell subsets remained significantly lower in responders in comparison with those in the healthy donors, while a significantly decreased percentages of CD56+ and CD16+CD56+ lymphocytes were observed in non-responders, in comparison with those in healthy controls. Our study demonstrated that HER2+ breast cancer patients who have decreased percentages of CD16+, CD56+, and CD16+CD56+ lymphocytes may achieve response to trastuzumab-containing treatment.