Evaluating the impact of exercise in women living with indolent metastatic breast cancer: The EMBody trial

TPS12140 Background: Exercise is associated with improved survival, physical function, treatment tolerability, and quality of life in early-stage breast cancer. Prospective trials support the positive impact of exercise on cardiorespiratory fitness (CRF), physical function, and muscle mass. These same endpoints matter in metastatic breast cancer (MBC). CRF is a predictor of worse cancer- specific survival, and there is a high prevalence of physical impairment and sarcopenia in patients with MBC, both associated with worse quality of life and survival. Two previous exercise trials in those with MBC have found exercise to be not feasible or of limited benefit. These findings may be due to a heterogeneous participant population that is primarily receiving cytotoxic chemotherapy. Patients with MBC have variable disease trajectories and supportive care needs; those with indolent MBC have longer life expectancy, lower symptom burden and distinct priorities, and are well-positioned to participate in and benefit from an exercise program. The EMBody trial is focused on enrolling a homogeneous patient population with indolent, stable MBC and improving endpoints known to correlate with survival outcomes in this population. Here, we evaluate the impact of a multimodal exercise intervention on CRF, physical function, body composition, and PROs. This study will be a step toward redefining “survivorship” to extend to those living with MBC. Methods: In this prospective phase II trial (NCT05468034), 100 patients with MBC are randomized 1:1 to exercise intervention or wait-list control, stratified by baseline function. Eligible patients have no evidence of disease progression in the prior 12 months and may be receiving endocrine, targeted, immuno-, or antibody drug conjugate therapy. Patients receiving cytotoxic chemotherapy are not eligible as this subgroup did not benefit in prior trials. Target enrollment is 3-4 participants per month over 2.5 years, beginning January 2023. The virtually-delivered exercise intervention arm achieves moderate intensity exercise with oncology-certified exercise physiologists 3 days/week for 16 weeks. The 60-minute sessions include aerobic, resistance, balance and stretching exercises. The exercise arm receives informational sessions on the role of exercise in cancer and principles of habit and self-efficacy. The primary endpoint is 16 week change in CRF on a ramp treadmill test between the exercise and control arms. Secondary endpoints include change in a physical function battery, muscle mass assessed by CT scans, and PROs of fatigue and quality of life. Exploratory analysis includes behavioral modifiers of exercise adherence and effectiveness and serologic measures of inflammatory, metabolic, and immune pathway biomarkers, as well as changes in circulating tumor cells. Patients will be followed post- intervention for sustained behavior change and survival trajectory. Clinical trial information: NCT05468034 .