Background: The prognosis for advanced/metastatic TNBC remains poor and novel therapeutic strategies are urgently needed. Insulin resistance and obesity contribute to TNBC progression and are independent predictors of worse survival. Methionine aminopeptidase 2 (MetAP2/p67) is overexpressed in many tumor types including breast. MetAP2 inhibitors exhibit broad anti-tumor activity and attenuate the effects of metabolic dysfunction on tumor growth. Evexomostat (SDX-7320) is a second-generation MetAP2 inhibitor that improved insulin sensitivity, reduced fat mass, and normalized adipokine levels in preclinical models of obesity and reduced tumor growth in TNBC preclinical models. In phase 1 trials, evexomostat monotherapy partially restored insulin sensitivity, reduced adipokines, and showed anti-metastatic effects in patients with advanced solid tumors. The goal of this phase 2 study is to test whether evexomostat prevents worsening of insulin resistance and augments tumor response in patients with metastatic TNBC and metabolic dysfunction in combination with eribulin chemotherapy, a standard of care treatment option after prior anthracycline and taxane exposure. Methods: This is a single-center phase 2 randomized control trial of evexomostat, a MetAP2 inhibitor, and eribulin chemotherapy. Key eligibility criteria include metastatic TNBC, measurable disease or ≥1 predominantly lytic bone lesion, baseline hemoglobin A1c >5.5% and/or BMI ≥30 kg/m2, and ≤2 prior lines of therapy in the advanced/metastatic setting. Patients with uncontrolled or insulin-dependent type II diabetes, or who require combination antihyperglycemic therapy are excluded. During the safety run-in period, 15 patients will be assigned to receive evexomostat 49 mg/m2 Q2 weeks and eribulin 1.4 mg/m2 on days 1 & 8 of a 21-day cycle. Upon safety confirmation, an additional 40 patients will be randomized 2:1 to receive evexomostat or placebo with eribulin. The primary endpoint is metabolic efficacy assessed by change in Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) score. Secondary endpoints include objective response rate, progression-free survival, safety and tolerability, patient-reported outcomes, and changes in metabolic markers and body composition. Historically, HOMA-IR scores double during chemotherapy, and this trial will test whether evexomostat attenuates the expected HOMA-IR rise. This trial will have >90% power to detect a difference between a 1.5-fold change in HOMA-IR in the control arm vs. no change in the evexomostat arm while controlling the Type I error at 5%. As of Feb 2022, 3 patients are enrolled; total accrual of 61 patients is planned with a goal of 55 evaluable patients. Clinical trial information: NCT05570253.