Investigation of peripheral blood immune cell subsets and cytokine levels in females living with breast cancer before and after first-phase chemotherapy

Abstract

Introduction: Breast cancer is the most frequently diagnosed cancer in females in sub-Saharan Africa and up to 80% of cases are stage 3 or 4 tumours. Triple-negative breast cancer (TNBC) accounts for up to 20% of all breast cancer cases and is aggressive, highly metastatic, tends to be diagnosed in younger women, and has a 5-year survival rate of 60%. This breast cancer subtype has limited treatment options due to its hormone insensitivity and heightened proliferative potential. The tumour microenvironment is a key driver of tumourigenesis and consists of different cancer cell clones, normal stromal cells, cytokines, chemokines, growth factors, and immune cells. Manipulation of the tumour microenvironment by cancer cells to promote tumour progression and metastasis has been observed in both breast and other cancer types and affects treatment response and patient prognosis. Immune cells and cytokines within the tumour microenvironment and the circulation may play a pro- or anti-tumourigenic role in TNBC and therefore act as potential surrogate biomarkers. The aim of this study was to compare immune cell subsets and cytokine levels in peripheral blood between healthy donors and TNBC patients, and in patients before and after first-phase (at least 3 cycles) of chemotherapy.

Methods: Twenty-three patients recently diagnosed with TNBC and ten healthy donors consented to participate in this study. Patients were recruited from a private clinic in Johannesburg, Gauteng with their consent. Blood was collected prior to treatment and after first-phase chemotherapy. Full blood counts, patient demographics, and treatment response were recorded. The percentage of circulating CD4+ and CD8+ T-cells, B-cells, natural killer (NK) cells, monocytes, and regulatory T-cells (Tregs) as well as the expression of various cell markers was evaluated by flow cytometry and compared between participant groups. The concentrations of vascular endothelial growth factor (VEGF), granulocyte-macrophage colony stimulating factor (GM-CSF), growth and differentiation factor 15 (GDF-15), Interleukin-6, -8, and -10 (IL-6, -8, -10) and interferon gamma-induced protein (IP-10) were evaluated in participant plasma by enzyme-linked immunosorbent assays (ELISAs) and the results were compared between participant groups. These were also compared to treatment outcomes.

Results: This study showed an increase in the percentage of CD14+ monocytes and CD56high NK cells, and a decrease in CD19+ B-cells after first-phase chemotherapy, while no significant differences in cell percentages were seen between healthy donors and treatment-naïve patient groups. The expression of CD206 was increased in B-cells and monocytes, while HLA-DR expression was increased on NK cells after first-phase chemotherapy. While little difference in the median Treg percentage was observed between patient groups, changes in the number of Tregs were observed after first-phase treatment when looking at individual patients, suggesting that observations may be patient-specific. An increase in expression of CD39, CD45RA, Helios, and CD127 was observed in Tregs after first-phase treatment. The concentrations of VEGF and GM-CSF were similar between patient and healthy donor groups, while IL-6, -8, and -10, and IP-10 and GDF-15 were increased in the post first-phase treatment plasma.

Conclusion: This study provides valuable insights into the dynamic changes in immune cell subsets and cytokine levels in TNBC patients undergoing chemotherapy. The observed alterations in T-cells, B-cells, NK cells, monocytes, and Tregs, along with their associated markers, suggest a complex interplay between the immune system and cancer progression. The increased levels of specific cytokines post-treatment highlight potential biomarkers for monitoring treatment response and disease progression. These findings contribute to our understanding of the immune landscape in TNBC and may inform future strategies for immunotherapy and personalized treatment approaches. Further research is warranted to elucidate the functional implications of these changes and their potential as prognostic indicators or therapeutic targets in TNBC management.