FDA Approves Camizestrant: Key Nursing Roles in New Breast Cancer Paradigm

The US Food and Drug Administration (FDA) granted accelerated approval to the oral selective estrogen receptor degrader (SERD) camizestrant (Etcamah, AstraZeneca) in combination with a cyclin-dependent kinase (CDK) 4/6 inhibitor (abemaciclib, palbociclib, or ribociclib).

The approval is indicated for adult patients with hormone receptor (HR)-positive, HER2-negative locally advanced or metastatic breast cancer whose tumors harbor an emerging estrogen receptor-1 (ESR1) mutation detected during first-line aromatase inhibitor (AI) and CDK4/6 inhibitor therapy. Concurrently, the FDA approved the Guardant360 CDx assay as a companion diagnostic to identify ESR1 mutations via circulating tumor DNA (ctDNA) liquid biopsy.

In an interview with Oncology Nursing News, Erica L. Mayer, MD, MPH, director of Breast Cancer Clinical Research at the Dana-Farber Cancer Institute, discussed how this introduces a new paradigm in cancer care. Rather than waiting for scans to show visible disease progression, oncology teams will use serial blood testing to intercept endocrine resistance at its molecular origin.

Key Takeaways for Oncology Nurses

• Preemptive Switch Efficacy: Transitioning to camizestrant upon ESR1 detection reduces the risk of disease progression or death by 56%, extending median progression-free survival (PFS) from 9.2 to 16.0 months (HR, 0.44; 95% CI, 0.31-0.60; p < 0.0001).
• Quality of Life Maintenance: The anticipatory switch extends the median time to quality-of-life deterioration from 6.4 months in the control group to 21.0 months with camizestrant (HR, 0.54; 95% CI, 0.34-0.84).
• Proactive Clinical Workflows: To avoid clinical bottlenecks, nurses can coordinate ctDNA blood draws approximately two weeks before scheduled restaging scans, ensuring all molecular and radiographic data are available at the patient's clinic visit.
• Favorable Tolerability Profile: Camizestrant is highly tolerated, with discontinuation rates due to adverse events at 1.3% compared with 1.9% in the standard AI group.
• Specific Side Effect Counseling: Nurses must educate patients on two unique side effects: transient photopsia (visual flashing in low-light conditions) and asymptomatic resting bradycardia.

Explaining the "Anticipatory Switch" and Mitigating Anxiety

Under the traditional treatment model, patients with HR-positive metastatic breast cancer remain on their first-line therapy until standard radiographic imaging reveals tumor progression. The Phase III SERENA-6 trial (NCT04964934) establishes an "anticipatory adaptive oncology" model. By performing serial ctDNA blood tests every two to three months alongside routine imaging, clinicians can identify emerging ESR1 mutations. These mutations drive acquired endocrine resistance and occur in roughly 30% of patients during first-line therapy.

Oncology nurses are the primary educators during treatment transitions. Mayer noted that clinicians initially worried that detecting a resistance mutation in the absence of physical progression might heighten patient anxiety. Her clinical experience in the SERENA-6 trial demonstrated the opposite. Patients welcomed this precise, proactive monitoring method, finding it empowering because it allowed clinical teams to act on early resistance data before the tumor could grow or diversify. Nurses should counsel patients that a positive ctDNA test is not an immediate clinical failure, but an early molecular alert that allows clinicians to precisely adjust the endocrine backbone to extend disease control.

Workflow Logistics and ctDNA Clearance

Integrating serial ctDNA testing into clinical workflows requires precise coordination. Mayer recommends a structured timeline to prevent administrative bottlenecks. Because ctDNA assays require approximately 2 weeks to return results, oncology nurses should schedule the blood draw 2 weeks prior to the patient’s scheduled restaging scan. This alignment ensures that clinicians have comprehensive clinical, radiographic, and molecular data ready at the patient's 3-month restaging visit.

Nurses can also use biomarker trends to encourage patients. In SERENA-6, switching to camizestrant led to a median 99% reduction in total ctDNA by week eight, with 51% of patients achieving complete ctDNA clearance (undetectable levels). Those remaining on standard AIs experienced a median 64% increase in total ctDNA, with only 1.9% achieving clearance. Complete ctDNA clearance is associated with overall survival advantages, making this a powerful educational tool for nurses to explain how the drug successfully eliminates its molecular target.

Toxicity, Safety, and Monitoring Guidelines

The recommended dose of camizestrant is 75 mg orally once daily, taken with or without food, combined with a continued CDK4/6 inhibitor at its current dosage. Prescribing information contains a boxed warning for arrhythmia due to QTc interval prolongation when used with other QTc-prolonging drugs. Warnings also cover bradycardia and embryo-fetal toxicity.

Nurses must screen concomitant medications for drug-drug interactions, perform baseline and periodic electrocardiograms, and monitor heart rates. When counseling patients, nurses should describe photopsia as a benign, temporary effect involving peripheral light flashes in low light that lasts only seconds and does not impair visual acuity. Mayer noted that reassure-centered counseling will prevent unnecessary patient distress and ensure long-term adherence.

References

1. Food and Drug Administration. FDA grants accelerated approval to camizestrant with a CDK4/6 inhibitor for ESR1-Mutated HR-positive, HER2-negative locally advanced or metastatic breast cancer. FDA. Published September 4, 2026. Accessed September 8, 2026.
2. Bidard FC, Mayer EL, Park YH, et al. First-line camizestrant for emerging ESR1-mutated advanced breast cancer. N Engl J Med. 2025;393(6):569-580.
3. Bidard FC, Barrios C, Bianchini G, et al. SERENA-6 interpretation and clinical implications: intercepting endocrine resistance in metastatic breast cancer. NPJ Breast Cancer. 2026;12(1):18.