Correlative studies investigating effects of PI3K inhibition on peripheral leukocytes in metastatic breast cancer: potential implications for immunotherapy
- 6 August 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in Breast Cancer Research and Treatment
- Vol. 184 (2), 357-364
- https://doi.org/10.1007/s10549-020-05846-5
Abstract
Purpose Patients with localized breast cancer have a 5-year survival rate > 99% compared to patients with metastatic breast cancer (MBC) that have a 5-year survival rate of similar to 27%. Unregulated PI3K/AKT signaling is a common characteristic of MBC, making it a desirable therapeutic target for tumors with activating mutations in this pathway. Interestingly, inhibition of the PI3K/AKT pathway can affect signaling in immune cells, which could potentially alter the immune phenotype of patients undergoing therapy with these drugs. The purpose of this study is to evaluate how PI3K inhibition affects the immune cells of MBC patients during treatment. Methods We investigated the effects of PI3K inhibition on the immune cell populations in peripheral blood of MBC patients enrolled in 4 different clinical trials utilizing PI3K inhibitors. Peripheral blood was drawn at different points in patient treatment cycles to record immune cell fluctuations in response to therapy. Results MBC patients who responded to treatment with apositive fold-change in cytotoxic T cell population,had an average duration of treatment response of31.4 months. In contrast, MBC patients who responded to treatment with anegative fold-change in cytotoxic T-cell population,had an average duration of therapeutic response of5 months. These data suggest that patients with a more robust, initial anti-tumor T cell response may have a longer therapeutic response compared to patients who do not have a robust, initial anti-tumor T cell response. Conclusions These results highlight the potential for PI3K inhibition to sensitize tumors to immune checkpoint inhibitors, thus providing additional therapeutic options for patients with MBC.Keywords
Funding Information
- National Cancer Institute (CA34590, P50CA098131, 5T32CA009592 30)
- Breast Cancer Research Foundation (IIDRP-16-001)
- U.S. Department of Veterans Affairs (5101BX000196-04)
- National Institutes of Health (CA90625)
- Vanderbilt University (P30 CA68485)
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