The long-lasting anti-tumor activity of cisplatin affecting the sustainable systemic immune alteration may improve distant-disease free survival of triple-negative breast cancer in patients with a substantial residual tumor following preoperative chemotherapy: A retrospective analysis with translational research.

Abstract

e12631 Background: Residual disease after preoperative chemotherapy is known to be a poor prognostic factor in triple-negative breast cancer (TNBC). Perioperative use of cisplatin (CDDP) is a well-known, standard treatment for most tumors except breast cancer. In this study, we explore the long-lasting anti-tumor activity of CDDP for TNBC patients. Methods: This research was based on consecutive study of seventy-nine previously untreated stage I–III TNBC patients treated with or without CDDP-based preoperative chemotherapy from 2007 to 2018 at the Kyoto University Hospital. We calculated the residual cancer burden (RCB) using the RCB calculator. All patients were sorted according to their RCB class: the pathological complete response (pCR), and RCB class I (minimal), II (moderate) or III (extensive). Distant disease-free survival (DDFS) was analyzed using the Kaplan-Meier method. Using mass spectrometry, we measured platinum concentrations in serum and normal breast tissue removed during surgery from patients treated with any platinum agents. We examined multiplex cytokine assays from serum sequentially, comparing CDDP and non-CDDP groups. Results: Forty-seven cases were treated with CDDP, and thirty-two did not have CDDP. The pCR rate was 53.2% for the CDDP group and 21.9% without CDDP. Patients with pCR and RCB class I were all distant disease-free. There was no significant difference between each RCB class using CDDP. However, patients belonging to RCB classes II and III with CDDP showed a better prognosis than the same RCB classes without CDDP (hazard ratio = 0.12). Platinum concentrations in serum were correlated with the time from the last dose of platinum agents, but platinum was even detected in serum two years after CDDP. No significant difference was found in the platinum concentrations of serum or normal breast tissue in the pCR and non-pCR groups. We also found that there were significant cytokine expression alteration related to T-cell infiltration only in the CDDP group one year after operation. It is suggested that CDDP may even affect the systemic immune alteration one year after operation. Conclusions: Our data shows that CDDP- based chemotherapy improves DDFS in patients with a substantial residual tumor. CDDP seems to sustain anti-tumor activity for a number of years and interaction with the systemic immune alteration.