Tirzepatide May Increase AEs in HR+/HER2– Breast Cancer Treatment

During a conversation with CancerNetwork® at the 2024 San Antonio Breast Cancer Symposium (SABCS), Coral Omene, MD, PhD, said that the phase 2 FITWISE trial (NCT06518837) assessing the outcomes that tirzepatide (Zepbound) elicits in patients with early-stage hormone receptor (HR)–positive, HER2-negative breast cancer will also be evaluating how the agent should be used in conjunction with breast cancer interventions.

The primary goal of the FITWISE trial is to identify how many patients enrolled achieve a reduction of 5% bodyweight by the end of study treatment. Incidence of adverse events (AEs) and feasibility assessed by completion of treatment course and discontinuation rates are secondary end points.

Omene, program director for the Breast Cancer Disparities Research, a medical oncologist and associate professor of medicine at the RWJ Medical School and at the Rutgers Cancer Institute of New Jersey, stated that one of the objectives of the study is safety, tolerability, and discontinuation rates. These data are not currently known because, as she said, this is the first prospective breast cancer trial for tirzepatide.

To this point, the team behind the trial has not discovered anything noteworthy that physicians need to be aware of. The trial, Omene emphasized, was structured so that patients could be seen often and assessed for AEs. No AEs of concern or worry have been identified.

Transcript:

[If there are any issues with tirzepatide while patients are being treated for breast cancer] is something that we will also be assessing. 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]. From our extensive research in looking at potential interactions with non-breast cancer drugs and tirzepatide, there is nothing that comes up that is of concern that one needs to make a particular note of, have a particular awareness of, or prepare for [when used in conjunction with breast cancer treatment agents]. 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. Our pharmacy helped us do that as we prepared to design this trial.

Reference

Omene C, George M, Kowzun M, et al. FITWISE: feasibility study of tirzepatide for weight loss intervention in early stage hormone receptor positive/HER2 negative breast cancer. Presented at: 2024 San Antonio Breast Cancer Symposium; December 10-13; San Antonio, TX. Abstract P2-08-25.