This is a prospective, randomized, controlled mono-center study investigating the effects of a combined, supervised aerobic exercise and resistance training in female patients with newly diagnosed, therapy-naive triple-negative breast cancer (TNBC, stage I-III) between 18 and 50 years of age scheduled for anthracycline-based chemotherapy and immunotherapy with checkpoint inhibitors. All patients will receive smart watches for rhythm monitoring.

Patients will be randomized (1:1) into a control group, receiving 24 weeks of standard exercise recommendations during neoadjuvant therapy, and an intervention group receiving 24 weeks of home-based, video-supervised exercise training consisting of endurance and resistance training. The primary endpoint is the change of peak oxygen consumption (VO2peak) between baseline and 24 weeks in the groups. Secondary endpoints include changes of physical function (short physical performance battery, SPPB), as well as cardiac biomarkers, quality of life, and changes of strength of the upper and lower body between baseline and 24 weeks. In addition, variables of cardiopulmonary exercise testing (CPET), resting and stress echocardiography, and burden of atrial fibrillation (AF) will be assessed. All changes in variables will be analyzed from baseline until 52 weeks as well.

Both groups will receive standard exercise recommendations after 24 weeks and will be followed-up by clinical examination after 52 weeks. Echocardiographic variables (at rest and during exercise), quality of life, CPET, SPPB, strength testing, burden of AF, and cardiac biomarkers will be assessed. Changes between the end of the intervention period 24 weeks after diagnosis and the end of follow-up after 52 weeks will be analyzed. In addition, changes in variables between baseline and 52 weeks will be analyzed.

As an exploratory endpoint the incidence of cancer therapy-related cardiac dysfunction (CTRCD) and immune-checkpoint inhibitor- associated myocarditis (ICI-myocarditis) will be assessed after 24 and 52 weeks.

This is a prospective, randomized, controlled mono-center study investigating the effects of a combined, supervised aerobic exercise and resistance training in female patients with newly diagnosed TNBC (stage I-III) between 18 and 65 years of age scheduled for anthracycline-based chemotherapy and immunotherapy with checkpoint inhibitors. All patients will receive smart watches for rhythm monitoring. Patients will be advised to trigger electrocardiogram (ECG) measurements every day at 8 a.m., 2 p.m. and 8 p.m. as well as before and immediately after every training session (intervention group only). In addition, ECG should be recorded whenever symptoms occur.

Patients will be randomized (1:1) into a control group, receiving 24 weeks of standard exercise recommendations during neoadjuvant therapy, and an intervention group receiving 24 weeks of home-based, video-supervised exercise training consisting of endurance and resistance training.

At baseline clinical examination, quality of life, cardiac biomarkers, resting and stress echocardiography and CPET will be performed. SPPB and strength of the upper and lower body will be assessed.

Training in the intervention group will be performed 5x/week with 20 minutes/session and will contain resistance training and endurance training as a mixture between moderate continuous and high-intensity interval training. Training corridors based on heart rate will be prescribed with the aid of CPET testing at baseline and during follow-up visits. Intensity will be progressively increased, but will be individually adapted to the schedule and response to chemo- and immunotherapy.

Follow-up visits will be performed six and twelve weeks after diagnosis and clinical examination, cardiac biomarkers, resting and stress echocardiography and CPET as well as testing of muscle strength, SPPB, and quality of life will be repeated. Prescribed training corridors of heart rate will be adapted after each test. Upon clinical suspicion for adverse events, such as ICI-myocarditis, magnetic resonance imaging of the heart will be performed and training will not be continued.

The primary endpoint is the change of VO2peak between baseline and 24 weeks in the groups. Secondary endpoints include changes of variables between baseline and 24 weeks, including SPPB, cardiac biomarkers, quality of life, changes of strength of the upper and lower body (knee extensor and biceps muscles), variables of CPET, resting and stress echocardiography, and burden of AF. Changes in variables between baseline and after 52 weeks will also be analyzed. 24h- Holter monitoring will be performed at the end of weeks 24 and 52.

Both groups will receive standard exercise recommendations after 24 weeks and will be followed-up by clinical examination after 52 weeks: Resting and stress echocardiography, quality of life, CPET, SPPB, strength testing, AF burden, and cardiac biomarkers will be re-assessed.

As an exploratory endpoint the incidence CTRCD and ICI-myocarditis will be assessed after 24 and 52 weeks.

Inclusion Criteria:

• Female patients with newly diagnosed, local triple-negative breast cancer (stage I-III) ≥ 18 to 65 years of age scheduled for immunochemotherapy with pembrolizumab and anthracycline-based chemotherapy

Exclusion Criteria:

• Unstable cardiac condition (clinical suspicion of progress or unstable coronary artery disease, signs of acute heart failure, haemodynamically relevant arrhythmias)
• Orthopaedic disability to exercise

Female breast cancer patients as defined by the treating gynaecologist

Information can be attained from the principal investigator Simon Wernhart on reasonable request

The principal investigator, who will assess outcomes, will be blinded to group allocation. Patients will be randomized by a staff member. Data analysis will be done by a professional statistician.