SABR PRIMER - Evaluating Stereotactic Ablative Radiotherapy for Primary and Regional Breast Tumors (SABR PRIMER)

A Phase II Trial Evaluating Stereotactic Ablative Radiotherapy for Primary and Regional Breast Tumors (SABR-PRIMeR)

The study is being done to determine if stereotactic ablative radiotherapy (SABR) can control tumour growth for patients with metastatic breast cancer.

Secondary objectives will be overall survival, progression-free survival and time to switch of next line of systemic therapy.

Radiation-related adverse events will be assess, with a specific focus on dermatitis, lymphedema and brachial plexopathy.

The exploratory objective is to correlate toxicities and outcomes with peripheral blood biomarkers and circulating tumor DNA to potentially help predict responses in future patients receiving combined therapy.

Study Overview

• Status: Not yet recruiting
• Conditions: Breast Cancer; Metastases
• Intervention / Treatment: Radiation: SABR

Detailed Description

Purpose:

The purpose of this study is to determine if stereotactic ablative radiotherapy (SABR) can provide effective locoregional control for patients with metastatic breast cancer. As secondary objectives, the investigators will assess the overall survival, progression-free survival and time to switch of next line of systemic therapy. The investigators will also assess radiation-related adverse events using CTCAE v5.0, with a specific focus on dermatitis, lymphedema and brachial plexopathy. Finally, as an exploratory objective, the investigators aim to correlate toxicities and outcomes with peripheral blood biomarkers and circulating tumor DNA to potentially help predict responses in future patients receiving combined therapy.

Primary Objective:

• Assess median, 1-year and 2-year locoregional control

Secondary Objectives:

• Assess median, 1-year and 2-year overall survival
• Assess median, 1-year and 2-year progression-free survival
• Assess median time to systemic therapy switch
• Assess radiation-related adverse events using CTCAE v5.0

Correlative Objectives:

• Correlate outcomes with peripheral blood-derived parameters

Research Design The trial is designed as a single-arm interventional study investigating stage IV breast cancer with persistent or progressive locoregional disease despite the use of standard systemic therapy A retrospective study will be conducted to create a matched cohort to compare locoregional control rates with patients who received conventional fractionated radiotherapy.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sandy Chang; Phone Number: 6048776000; Email: sandy.chang@bccancer.bc.ca

Study Locations

• Canada
  • British Columbia
    • Vancouver, British Columbia, Canada, V5Z 4E6
      • BC Cancer - Vancouver
      • Contact: Sandy Chang; Phone Number: 6048776000; Email: sandy.chang@bccancer.bc.ca
      • Contact: Andrew Bang, MPH MD FRCSC

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Pathologically confirmed AJCC 7th/8th edition Stage IV invasive ductal carcinoma or invasive lobular carcinoma of the breast.
2. Measurable disease in the breast, suitable to receive radiotherapy.

3. Receiving or planned to receive systemic therapy.

   a. The following should be held for the duration of treatment: cytotoxic chemotherapy, CDK4/6 inhibitors, T-DXd

4. Patients are allowed to have SABR for oligometastatic disease as clinically indicated
5. Age 18 or older
6. ECOG Performance Status 0-2
7. Life expectancy greater than 6 months
8. Able and willing to provide informed consent
9. Able to complete patient reported outcome questionnaires

Exclusion Criteria:

1. Contraindications to radiotherapy, including a history of SLE, systemic scleroderma, IPF, ataxia telangiectasia, pregnancy
2. Previous history of locoregional radiotherapy to the ipsilateral breast

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Treatment; SABR treatment to Whole breast +/- regional lymph nodes	Radiation: SABR; Prescription dose/fractionation: 26Gy/5 with 40Gy/5 +/- 35Gy/5 Boost Radiation Technique: VMAT Treatment Frequency: Every other day (EOD)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Locoregional Control	Assess median, 1-year and 2-year locoregional control	2 Years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall survival	Assess median, 1-year and 2-year overall survival	2 Years
Progression Free Survival	Assess median, 1-year and 2-year progression-free survival	2 Years
systemic therapy switch	Assess median time to systemic therapy switch	2 Years
Adverse Events	Assess radiation-related adverse events using CTCAE v5.0	2 Years

Collaborators and Investigators

• Sponsor: British Columbia Cancer Agency

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2025
• Primary Completion (Estimated): June 30, 2029
• Study Completion (Estimated): July 30, 2030

Study Registration Dates

• First Submitted: April 15, 2025
• First Submitted That Met QC Criteria: April 15, 2025
• First Posted (Actual): April 22, 2025

Study Record Updates

• Last Update Posted (Actual): April 24, 2025
• Last Update Submitted That Met QC Criteria: April 22, 2025
• Last Verified: April 1, 2025

More Information

Terms related to this study

• Keywords: SABR
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Breast Neoplasms
• Other Study ID Numbers: H25-00274

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No