Systemic immune mediators predict therapeutic response and tumor-infiltrating lymphocyte intensity in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer defined by the lack of expression of estrogen receptor, progesterone receptors, and of the human epithelial growth factor receptor 2. Neoadjuvant chemotherapy has proven efficacy in the treatment of TNBC, and a pathological complete response (pCR) is predictive of improved long-term survival. The immune response exerts a vital role in response to neoadjuvant chemotherapy, as indicated by the relation between the percentage of stromal tumor-infiltrating lymphocytes (TILs) in pre-treated tumor tissue samples and the likelihood of achieving pCR. Despite this, the relationship between the systemic immune response and the tumor microenvironment is unclear. In this prospective study, we determined the systemic plasma immune profile of TNBC patients before treatment using a panel of 27 immune mediators and measured the percentage of TILs from the same patients. Patients who demonstrated pCR had significantly higher systemic immune mediators; GM-CSF, FGF-basic, VEGF, IL-2, and IL-5, than the non-responders. Moreover, responders displayed a strong positive correlation between the cytokines IFN-γ and IL-7 with the percentage of TILs, while non-responders had a negative or no correlation. Finally, systemic immune mediator levels before treatment predict pCR (AUC range 0.64 - 0.71), and the combination of immune mediators and TILs improved pCR prediction (AUC 0.71 - 0.82). In conclusion, increased systemic immune mediators reflect increased TILs percentage and act as potential predictive biomarkers of pCR for TNBC patients submitted to neoadjuvant chemotherapy. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was funded with support from CNPq, PRONON, and INCT- INCITO/CNPq. KJG, DMC, ATC are CNPq research fellows. FAPESP, CAPES and CNPq for graduate student fellowships. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the local Ethics Committee. A written informed consent was obtained from each patient at the time of diagnosis and before the initiation of any procedure. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The datasets generated during the current study are available from the corresponding author on reasonable request.