FITWISE Trial Explores Tirzepatide's Impact on Weight Loss and Safety in Early-Stage HR+/HER2- Breast Cancer

• The FITWISE trial (NCT06518837) is evaluating tirzepatide (Zepbound) for weight loss in patients with early-stage HR+/HER2- breast cancer, assessing its safety and tolerability alongside breast cancer treatments.
• The primary endpoint of the phase 2 FITWISE trial is to determine the proportion of patients achieving at least a 5% body weight reduction by the end of the treatment course.
• Secondary endpoints include monitoring the incidence of adverse events (AEs) and assessing the feasibility of tirzepatide treatment based on completion and discontinuation rates.
• Preliminary assessments from the FITWISE trial have not identified any significant adverse events of concern, but continuous monitoring is in place due to the novelty of tirzepatide use in this population.

The phase 2 FITWISE trial (NCT06518837) is underway to investigate the effects of tirzepatide (Zepbound) on weight loss in patients with early-stage hormone receptor-positive (HR+), HER2-negative breast cancer, while also evaluating the agent's safety and tolerability in conjunction with standard breast cancer interventions. Coral Omene, MD, PhD, from the RWJ Medical School and Rutgers Cancer Institute of New Jersey, shared insights on the trial's objectives and preliminary findings at the 2024 San Antonio Breast Cancer Symposium (SABCS).

The FITWISE trial's primary goal is to determine the percentage of enrolled patients who achieve a minimum of 5% body weight reduction by the end of the study treatment. Secondary endpoints include the incidence of adverse events (AEs) and feasibility, measured by treatment course completion and discontinuation rates.

Safety and Tolerability Assessments

Dr. Omene emphasized that a key objective of the FITWISE trial is to assess the safety, tolerability, and discontinuation rates associated with tirzepatide in this specific patient population. As this is the first prospective breast cancer trial involving tirzepatide, these data are currently unknown. The trial is structured to allow frequent patient monitoring and AE assessment. So far, no AEs of significant concern have been identified.

Ongoing Monitoring for Adverse Events

According to Dr. Omene, the study design incorporates frequent patient visits and assessments to monitor for potential AEs. The pharmacy team assisted in the trial's design to proactively address potential interactions between tirzepatide and other medications used in breast cancer treatment. While extensive research has not revealed any concerning interactions between tirzepatide and non-breast cancer drugs, continuous monitoring is essential due to the novelty of using tirzepatide in this context.

"One of our objectives is safety, tolerability, and discontinuation rates; we do not know them, because this is the first prospective breast cancer trial [for tirzepatide]," Dr. Omene stated. "Obviously, we need to assess for AEs, and the study is designed to see patients often and assess for AEs, but, as of yet, there are no concerning or worrisome AEs based on our research."