In advanced breast cancer (ABC) some studies suggest a deleterious effect on survival when high levels of myeloid-derived suppressor cells (MDSC)1,2 are detected in peripheral blood. Furthermore, classical therapies like anthracyclines or gemcitabine seem to exert an immunostimulating effect by eliminating and/or altering the function of MDSC3. The objective of this study is to analyze the evolution of blood MDSC in patients with ABC prior to the standard first-line systemic therapy according to Clinical Practice Guidelines.
MDSC levels are measured at three timepoints: basal, and after 2 and 6 months from first line systemic therapy onset. Data are compared the measurements obtained from the MDSC of a control group of healthy women. In addition, MDSC levels are monitorized and correlated with clinical outcomes in terms of overall response rate [clinical benefit (CB, complete response + partial response + stabilization lasting more than 24 weeks) versus (vs.) progression of disease (PD)].
A total of 39 patients with ABC (34 CB, 5 PD) and 20 healthy women have been analyzed. 34 out of 39 patients were considered to obtain CB and 5 patients (12,82%) had PD as best response. Basal MDSC levels were higher in ABC patients prior to initiate any systemic therapy vs healthy population (p < 0,001). The levels of MDSC decreased sharply in those patients with CB (p 0,001), reaching statistical significance. However, no statistically significant differences were found in patients with PD (p 0,317) with respect to basal levels of MDSC (Table).
Basal MDSC levels are higher in patients diagnosed with ABC compared to the healthy population. Systemic therapy seems to decrease the levels of blood MDSC of patients with ABC, which may eventually help to restore a better immunosurveillance profile in ABC patients that could impact on clinical evolution.
The authors.
Andalusian Public Progress and Health Foundation.
All authors have declared no conflicts of interest.
Evolution of the MDSC according to clinical response in ABC and basal MDSC in healthy cohort There is only one patient analyzed in cycle 6 with PD. DP, progression of disease; CB, clinical benefit; ABC, advanced breast carcinoma; MDSC, myeloid-derived suppressor cells; 95% CI, 95% confidence interval.MDSC_Basal (mean) MDSC_Cycle_3 (mean) MDSC_Cycle_6 (mean) P value PD ABC 25,97 (95% CI: 6,47-45,47) 5,38 (95% IC: 4,05-6,71) 1,79* 0,317 CB ABC 13,03 (95% CI: 7,24-18,83) 3,90 (95% IC: 2,56-5,23) 2,98 (95% IC: 1,99-3,98) 0,001 Healthy cohort 0,81 (95% CI: 0,52-1,10) – – <0,001