e12521 Background: Approximately 70% of breast cancers are hormone receptor (HR)–positive, for which endocrine therapy (ET) is a cornerstone of treatment. However, up to one-third of patients discontinue ET due to adverse events, most commonly vasomotor symptoms (VMS). Fezolinetant, a neurokinin 3 receptor antagonist approved in 2023 for menopausal VMS, has not been studied in patients with breast cancer. Given the need for nonhormonal options for the management of VMS, we conducted an observational, survey-based study evaluating the use of fezolinetant in patients with breast cancer. Methods: This is a single-institution, observational cohort study of adults (≥18 years) with stage 0–IV breast cancer receiving ET who were prescribed fezolinetant for ≥4 weeks for VMS. Patients receiving ET for non-malignant high-risk lesions were excluded. Participants completed a one-time phone interview or REDCap survey assessing symptom severity, treatment response, time to improvement, adverse effects, treatment preference, and financial toxicity. Clinical data were abstracted from the electronic medical record. Outcomes were summarized using descriptive statistics. This study was IRB approved, and all patients provided informed consent. The data was monitored and reviewed for completeness and accuracy. Results: Of the 70 patients screened, 34 were enrolled. Mean age was 52.5 ± 10.3 years; all participants were female, 88.2% White, and 32.4% Hispanic/Latino. Most patients had invasive breast cancer (94.1%) with early-stage disease. Baseline symptom burden was high, with 79.4% reporting severe hot flashes and 90.9% experiencing ≥4 episodes daily. Prior unsuccessful therapeutic (prescribed or over-the-counter) management attempts were common (64.7%). Following fezolinetant initiation, 97.1% reported improvement in hot flashes, with 76.5% noting significant improvement and 76.5% reporting improvement in both frequency and severity. Symptom relief occurred within one week for 70.6% of patients. Fezolinetant was well tolerated, with most patients reporting no adverse effects and 91.2% planning to continue therapy. Insurance authorization challenges and high copays were reported in 26.5% and 32.4%, respectively. Conclusions: In this real-world observational cohort of patients receiving endocrine therapy, hot flashes were common, severe, and frequently refractory to prior interventions. Initiation of fezolinetant was associated with rapid, clinically meaningful improvement in hot flash frequency and severity, with high tolerability and treatment continuation. These findings support the feasibility and potential benefit of fezolinetant for the management of endocrine therapy–associated vasomotor symptoms in patients with breast cancer and warrant prospective investigation.
Haddad et al. (Thu,) studied this question.