Addition Of Dendritic Cell Vaccines To Neoadjuvant Chemotherapy In Her2 Negative Breast Cancer Patients

Primary breast cancer (BC) has shown a more prominent immune infiltration than the metastatic disease, justifying the optimal scenario for immunotherapy. Neoadjuvant chemotherapy (NAC) with immune checkpoint inhibitors has demonstrated an increase in pathological complete response (pCR) when added to NAC in triple negative (TN) BC patients. The aim of this is study is to evaluate the safety, feasibility and efficacy of the addition of dendritic cell vaccines (DCV) to NAC in HER2-negative early BC patients. Between February 2011 and September 2015, 39 patients with early HER2-negative BC were recruited to receive DCV in addition to NAC (21 in the clinical trial NCT01431196 and 18 under compassionate use) in 2 hospitals (CUN and CHN), constituting the vaccination group (VG), and 44 patients were recruited from CUN as the control group (CG). All patients received NAC (ddECx4 + TXTx4) followed by surgery ± radiotherapy ± hormonotherapy. VG patients received 5 DCV prior to surgery and the remaining as maintenance. Side effects (CCTAE v4.0), cPR (Miller&Payne) and follow-up data until disease progression (EFS) and death (OS) from any cause was collected. Median age: 49.7 years. At baseline, 56.6% of patients had stage II disease, 71% nodal involvement; 28% were LA, 36% LB and 36% TN. The pCR rate was 26.3% [MOU1] in the VG and 9.09% in the CG (p=0.03). Proportions by biologic subtypes in the VG vs CG were: 50.0% vs 30.7% in TN, 16.6% vs 0% in luminal B, and none among luminal A patients. Mean DCV/patient: 12 (range 6-26). Downstage to conservative surgery occurred in 13% of VG and 0% of CG (p < 0.01). There was no difference in grade 3-4 NAC toxicity between groups neither grade ≥ 3 vaccine-related adverse events. Median follow-up was 7.52 years. At the time of the analysis, the median EFS and OS have not been reached. During 5 years-follow-up, 13.15% in the VG versus and 17.5% in the CG had disease progression (p=0.77), while 5.2% in the VG vs 9.7% in the CG died (p=0.44). The combination of DCV and NAC is safe, tolerable and increase pCR, especially among TN patients. No impact in outcome was seen between groups.