Background: Adagloxad simolenin (A-S) is an anti-Globo H immunogen comprised of the carbohydrate tumor antigen Globo H, covalently linked to keyhole limpet hemocyanin, a carrier protein that deploys T cells to enhance the humoral response. Administration of A-S in combination with the immune adjuvant OBI-821 serves as an anti-tumor associated carbohydrate antigen vaccine intended to generate anti-Globo H humoral responses in patients with Globo H-expressing tumors. Methods: Study OBI-822-011, a phase 3 study, was initiated in 2018. Following feedback from investigators and advisors the study design was changed from a double-blind, placebo-controlled study to an open-label, standard of care (SOC) study. The revised protocol includes patients who have recovered from surgery and completed all planned neoadjuvant and/or adjuvant multiagent chemotherapy and/or radiation therapy. SOC in the A-S/OBI-821 arm is concomitant therapy of capecitabine or immune checkpoint inhibitor. In the SOC arm patients will receive SOC therapy consisting of observation alone, or adjuvant capecitabine alone, or immune checkpoint inhibitor alone. The key protocol changes included a change from open-label to standard of care, providing unblinding and reconsent guidelines for patients enrolled into the study prior to the protocol amendment, allowing concurrent adjuvant single agent chemotherapy, revising the stratification algorithm from a non-hierarchical to a hierarchical structure and aligning the stratification factors with prognostic factors more representative of the study population, revising the eligibility criteria, number and frequency of assessments to reduce patient burden, revising the interim analysis timepoints for futility, and removed an interim analysis for superiority. Study Objectives: Primary Objective:To determine the effect of A-S/OBI-821 treatment on improving IDFS in the study population. Secondary Objectives: To determine the impact of A-S/OBI-821 treatment on Overall survival (OS), Quality of life (QoL), Breast cancer-free interval (BCFI), Distant disease-free survival (DDFS) in the study population; To determine the safety and tolerability of A-S/OBI-821 in the study population. Key Exploratory Objectives: Beyond the safety, efficacy, and QoL endpoints of this trial, exploratory endpoints will evaluate the relationship between aberrant Globo H expression and baseline characteristics, including tumor pathology and immune factors. Conclusion: An estimated 668 subjects will be enrolled, treated for up to 2 years, and followed until occurrence of 187 events (invasive disease recurrence or death) or 3 years from last subject randomized. Survival follow-up is for 5 years from randomization of last subject. Clinical trial information: NCT03562637.