The purpose of this study is to find out how much oxygen is used during a cardiopulmonary exercise test (CPET) in women who have mild cardiotoxicity after standard treatment for HER2-positive breast cancer, and to see whether the results of this test can be used to predict how well participants' heart and lungs will work if they continue to receive this kind of treatment.

Inclusion Criteria:

• Age ≥ 18 years
• Female
• Diagnosed with a HER2-positive solid tumor (stage I-IV)
• Left ventricular dysfunction prior to the start of HER2-targeted therapy, defined by a LVEF < 53% (or lower limit of normal), or diagnosed with mild cardiotoxicity associated with HER2-targeted therapy, defined by an absolute decrease in LVEF ≥ 10% from pre-treatment to < 53%
• Planning to undergo treatment with HER2-targeted therapy (e.g. trastuzumab, pertuzumab, or ado-trastuzumab) for a minimum of 3 months (i.e. 4 cycles administered every 3 weeks).
• Willing and able to comply with the requirements of the protocol

Exclusion Criteria:

• Symptomatic heart failure (New York Heart Association Class III or IV)

• Subjects must not have any of the following absolute contraindications to cardiopulmonary exercise testing:

  • Acute myocardial infarction (within 30 days of any planned study procedures),
  • Unstable angina
  • Uncontrolled arrhythmias causing symptoms or hemodynamic compromise,
  • Symptomatic severe aortic stenosis
  • Recurrent syncope
  • Active endocarditis
  • Acute myocarditis or pericarditis
  • Acute pulmonary embolus or pulmonary infarction (within 3 months of any planned study procedures)
  • Thrombosis of lower extremities (within 3 months of any planned study procedures)
  • Suspected dissecting aneurysm
  • Uncontrolled asthma
  • Pulmonary edema
  • Room air desaturation at rest ≤ 85%
  • Respiratory failure
  • Acute noncardiopulmonary disorder that may affect exercise performance or be aggravated by exercise (i.e., infection, renal failure, thyrotoxicosis)
  • Mental impairment leading to inability to cooperate.

• Enrollment onto any other interventional investigational study

• Inability to provide informed consent

Potential research participants will be identified by a member of the participant's treatment team, the protocol investigator, or research team at Memorial Sloan Kettering Cancer Center (MSK). If the investigator is a member of the treatment team, s/he will screen their potential participant's medical records for suitable research study participants and discuss with the subject their potential for enrolling in the research study.

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.