During the phase II study, participants will have a research biopsy of the breast followed by one week of ruxolitinib given twice daily. A second research biopsy of the breast is then performed and the participants will then receive combination ruxolitinib (at the MTD dose defined in the phase I study) and standard dose paclitaxel for 12 weeks. Participants will be seen weekly during treatment. One week after completing the combination therapy, participants will receive standard dose doxorubicin and cyclophosphamide (AC) every 2 weeks for 4 cycles.