NCT06882499

Stereotactic Ablative Body Radiotherapy (SABR) With Maintenance of Systemic Therapy Versus Physicians' Choice of Systemic Therapy for Oligoprogressive ER-positive, Her-2 Negative Breast Cancer II

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 74 (estimated)
• Sponsor: Peter MacCallum Cancer Centre, Australia · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

The goal of this clinical trial is to assess Stereotactic Ablative Radiotherapy (SABR) as a method to delay a change in systemic therapy in patients with oligoprogressive ER-positive, HER2-negative advanced breast cancer. The main question it aims to answer is to assess whether the addition of SABR to continuation of first line endocrine therapy and CDK 4/6 inhibitor (Arm A) to patients with oligoprogressive ER-positive, HER2-negative advanced breast cancer could have longer time to strategy failure (TSF) in comparison to physician choice of systemic treatment (Arm B) in patients who had progressed first line. The treatment strategy in Arm A is to maintain patients on current endocrine therapy and CDK 4/6 inhibitor, controlling localised progressing sites of disease with SABR. Treatment strategy in Arm B is to maintain disease control with physician's choice of systemic therapy alone.

Detailed description

AVATAR II is a phase II multicentre open label, randomised trial. Following informed consent, eligible patients with ER-positive, HER2-negative advanced breast cancer receiving an ET (either AI or selective estrogen receptor degrader in combination with a CDK 4/6 inhibitor with newly diagnosed OPD amenable to SABR will be randomised to either: Arm A: SABR to all known sites of OPD with continuation of first line therapy ET and CDK 4/6 inhibitor Arm B: Physician's choice of systemic treatment Patients must have evidence of radiological response to ET and CDK 4/6 inhibitor for a minimum of six months prior to randomisation (defined as either stable disease or partial response). All patients will be followed up for 3 years after the last patient has been randomised.

Conditions

• Breast Cancer, Metastatic
• Metastatic Breast Cancer

Interventions

Type	Name	Description
RADIATION	Stereotactic Ablative Radiotherapy	Stereotactic Ablative Radiotherapy
OTHER	Physician's choice of systemic treatment	Physician's choice of systemic therapy does not mandate a change in systemic therapy, however, SABR is not permitted for management in this arm

Timeline

• Start date: 2026-06-01
• Primary completion: 2032-06-01
• Completion: 2032-06-01
• First posted: 2025-03-18
• Last updated: 2026-04-02