A Phase I, Multicenter, Open Label Study on the Effects of SNDX-275 on Expression of Biomarkers in Subjects With Newly Diagnosed Breast Cancer

Inclusion criteria: * Is scheduled for breast biopsy due to a suspicious mass palpable or ≥1 cm on mammogram * Must be able to receive two doses of study medication 7 days apart prior to surgery * Has histologically confirmed invasive breast cancer with ER positive, ER and/or PR negative histology or triple negative (for ER, PR, HER-2) histology * Has an ECOG performance status ≤ 2 * Has no clinically significant laboratory or cardiac abnormalities * Has a negative serum pregnancy test at Screening as is either post menopausal, sterile or willing to use an approved method of contraception. * Is able to swallow and retain oral medication Exclusion criteria: * Has a concomitant medical condition that precludes adequate study treatment compliance or assessment, such as: a. Bleeding disorders that would increase risks of additional core biopsy for biomarkers b. Morbid obesity * Is currently receiving treatment with a medication on the prohibited medication list * Has allergy to benzamides or inactive components of study drug * Is participating in another clinical trial or has received another investigational agent within 30 days prior to informed consent