The purpose of the study is to address the following hypotheses: (i) Anti-PD-L1 therapy with MEDI4736 administered concomitantly with weekly nab-paclitaxel followed by MEDI4736 concomitant with ddAC neoadjuvant chemotherapy will induce higher pathologic complete response (pCR) rate (>55%) in triple negative breast cancer than historical pCR rates (30-40%) observed with chemotherapy alone. (ii) MEDI4736 can be safely co-administered at full dose with sequential with nab-paclitaxel (100mg/m2) and ddAC (60 mg/m2 and 600 mg/m2 respectively).

The primary objective of the Phase I portion of the trial is to assess the safety of MEDI4736 combined with chemotherapy and determine if full dose of MEDI4736 can be administered concomitantly with full dose weekly nab-paclitaxel followed by dose-dense AC chemotherapies, respectively.

The primary objective of the Phase II portion of the study is to estimate the pCR rate with MEDI4736 in combination with weekly nab-paclitaxel x 12 treatments followed by MEDI4736 in combination with ddAC x 4 treatments for estrogen receptor (ER), progesterone receptor (PR) and HER2 negative (triple negative, TNBC), clinical stage I-III breast cancer. Pathologic complete response is defined as the absence of residual invasive cancer on hematoxylin and eosin evaluation of the resected breast specimen and all sampled regional lymph nodes following completion of neoadjuvant systemic therapy (i.e. ypT0/Tis ypN0).

Secondary objectives include: to assess the safety and toxicity of adding anti-PD-L1 antibody, MEDI4736 to standard of care neoadjuvant chemotherapy in the Phase II portion of the trial. The study will also monitor for events of special clinical interest with a suspected auto-immunologic etiology including grade ≥3 colitis, hyperthyroidism, hypophysitis, hypothyroidism, pneumonitis, rash and anti-drug-antibody (ADA) immune complex disease (manifested by symptoms of arthralgias, abdominal pain, back pain, and vasculitis).

Exploratory objectives include: to assess correlation between response to therapy and immune parameters of the tumor at baseline and post-treatment in patients who have residual cancer after therapy.

Inclusion Criteria:

1. Newly diagnosed histologically confirmed stage I-III, ER, PR and HER2 negative invasive breast cancer as defined by the ASCO CAP guidelines for whom systemic chemotherapy would be indicated based on physician judgment following standard NCCN practice guidelines.

2. Willing and able to provide written informed consent for voluntary participation in the trial.

3. Willing to undergo a baseline tumor core needle biopsy and blood draws for correlative science studies.

4. Eighteen years of age or older on the day of signing informed consent.

5. Female subjects must either be of non-reproductive potential or must have a negative urine or serum pregnancy test upon study entry.

6. Patients should have adequate organ function to tolerate chemotherapy, as defined by:

   • peripheral granulocyte count of > 1,500/mm3
   • platelet count > 100,000/mm3
   • hemoglobin >9 g/dL
   • total bilirubin < 1.5 x upper limit of normal (ULN)
   • aspartate aminotransferase (AST) and alanine aminotransferase (ALT) each < 1.5 x ULN
   • serum creatinine < 1.5 x ULN or serum creatinine clearance < 50mL/min
   • INR/PT/PTT each < 1.5 x ULN
   • TSH within normal limits

Exclusion Criteria:

1. Patients who underwent partial excisional biopsy or lumpectomy, segmental mastectomy or modified radical mastectomy or sentinel node.
2. Patients for whom anthracycline, paclitaxel or antibody therapies are contraindicated.
3. Patients with active autoimmune disease or documented autoimmune disease within 2 years. Patients with hypothyroidism that is clinically stable and have normal TSH levels with hormone replacement, or patients with vitiligo or psoriasis not requiring treatment remain eligible for the study.
4. Active or prior documented inflammatory bowel disease (Crohn's disease, ulcerative colitis).
5. Patients with known active hepatitis B or C or HIV infection or with history of tuberculosis.

Patients enrolled in Phase 2, 2 of 61 removed consent and withdrew, they are not presented here in the results (baseline characteristics and primary outcome) but were counted in the adverse events.

Up to 20 weeks

Adverse events are reported for Phase 1 doses combined and Phase 2. At the time of data collection in Phase 1, adverse events were collected at the patient level, not at the dosing level.