Background: Combining immune-checkpoint inhibitors with chemotherapy yielded high response rates in patients (pts) with metastatic TNBC. Therefore, we evaluated the addition of durvalumab, an anti-PD-L1 checkpoint inhibitor, to standard neoadjuvant chemotherapy in pts with primary TNBC. Methods: GeparNuevo randomized pts to durvalumab (D) 1.5 g i.v. or placebo every 4 weeks (wks). D/placebo monotherapy (0.75 g i.v.) was given for the first 2 wks (window phase), followed by a biopsy and D/placebo plus nab-paclitaxel (nP) 125 mg/m² weekly for 12 wks, followed by D/placebo plus epirubicin/cyclophosphamide (EC) q2 wks for 4 cycles. Randomization was stratified by stromal tumor infiltrating lymphocyte (sTILs) (low (≤10%), intermediate (11-59%), high (≥60%)). Pts with primary cT1b-cT4a-d disease, centrally confirmed TNBC and sTILs status were included. Primary objective compares pCR (ypT0 ypN0) rates. Secondary objectives are pCR rates in stratified subpopulations and according to other pCR definitions; response rates; breast conservation rate; toxicity; compliance and survival. Sample size was planned assuming a pCR rate of 48% for placebo based on the GeparSepto results and 66% for D (as clinically meaningful benefit), requiring 158 pts to show superiority of D (2-sided α=0.2, 80% power). Assuming a 10% drop-out rate, randomization of 174 pts was planned. Results: A total of 174 pts were enrolled between June 2016 and September 2017 and all pts had completed treatment. Median age was 49.5 years [range 23.0-76.0]; 44.5% of pts had cT1, 49.7% cT2, 3.5% cT3, 2.3% cT4; 83.3% G3 and 31.4% cN-positive tumors assessed by sonography; sTILs categories were 37.9% low, 47.7% intermediate, and 14.4% high; median Ki67 was 49.0% [range 3.0%-96.0%]. A total of 86 SAEs and 65 immune related AEs of special interest (irAESI) were reported; 34.5% of pts had at least one SAE and 27.6% had at least one irAESI. Overall, 84 of 174 pts (48.3% 95%CI [40.7-56.0]) had a pCR. Conclusions: Combination of chemotherapy with durvalumab/placebo yielded a high pCR rate in TNBC. Treatment was feasible. Unblinded results will be presented at the meeting. Funding and drug was provided by AstraZeneca and Celgene. Clinical trial information: NCT02685059