Impact of Vitamin D Supplementation on the Rate of Pathologic Complete Response in Vitamin D Deficient Patients

Inclusion Criteria: * Women or men with histologically confirmed invasive mammary carcinoma. * Known triple negative ER/PR/HER2 receptor status as defined by: * ER and PR less than or equal to 10% and * HER2 negative based on one of the following: * IHC 0 or 1+ * IHC 2+ and FISH negative * IHC 2+ and FISH equivocal and no indication for HER2 targeted therapy based on the treating investigators discretion (i.e., HER2: CEP17 ratio \< 2.0 or HER2 total copy number \<6) * Patients who plan to undergo neoadjuvant chemotherapy prior to definitive surgical management. Participants are eligible up to 2 weeks after initiating neoadjuvant chemotherapy. * ECOG performance status of 0, 1 or 2. * Age ≥ 18. * The effects of high dose vitamin D on the developing human fetus are unknown. For this reason, women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. * Ability to understand and the willingness to sign an IRB-approved informed consent document (either directly or via a legally authorized representative). Exclusion Criteria: * Patients with nephrolithiasis within the past year. * Patients with known sarcoidosis. * Patients with corrected calcium \>10.5 mg/dL within 30 days prior to initi…