Abstract
BACKGROUND: Triple negative breast cancer (TNBC) patients with residual disease after neoadjuvant chemotherapy (NAC) face high risk of recurrence. BREASTIMMUNE-03 trial evaluates the efficacy of nivolumab and ipilimumab combination compared to capecitabine as adjuvant treatment. METHODS: This multicentre, randomized open-label phase II trial included TNBC patients with Residual Cancer Burden (RCB) of class II-III after NAC and surgery, and allocated them to randomization (1:1) to receive nivolumab plus ipilimumab or capecitabine for 24 weeks. Randomization was stratified by center, ECOG performance status (PS) 0 or 1, and RCB Class. Primary endpoint was disease free survival (DFS), assessed in the intent-to-treat population. Safety analysis according to NCI-CTCAE V5.0 included all patients who received at least one dose of study drug. RESULTS: From July 2019 to October 2021, 95 patients were randomized to the nivolumab plus ipilimumab arm (NIVO + IPI n = 45), or to the capecitabine arm (CT n = 50). With a median follow-up of 34.3 (IQR 33-36) months, 39 events (relapse or death) were reported: 17 (38 %) for NIVO + IPI; 22 (44 %) for CT (HR 0.84, 95 %CI 0.45-1.59; log-rank test p-value 0.5938). 17 (38 %) patients in the NIVO + IPI arm prematurely discontinued treatment due to treatment-related adverse events (AEs), versus 7 (14 %) in the CT arm. CONCLUSION: A 6-month post-operative nivolumab plus ipilimumab treatment did not significantly improve DFS compared to capecitabine in TNBC patients with RCB II-III and resulted in increased immune-mediated AEs. Despite premature trial termination, our results do not support nivolumab plus ipilimumab adjuvant treatment in this setting. TRIAL REGISTRATION: NCT03818685.