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NCT Number: NCT06925984

Stereotactic Radiotherapy for Oligoprogressive ER+/HER- Metastatic Breast Cancer, a Prospective Phase 2 Study (Oligopro-Breast)

The Oligopro-Breast trial is a Phase II study targeting women with ER+/HER2- metastatic breast cancer who have been on endocrine therapy and/or CDK4/6 inhibitors for at least 6 months, and show progressive disease at 1-3 extracranial metastases, which are treatable locally. The trial aims to investigate if treating these resistant metastases with SBRT (or other local treatments if SBRT is not possible) can extend the use of the current systemic therapy.

Patients will continue their existing systemic treatment while receiving SBRT on all progressive lesions. If new oligoprogression occurs, SBRT will be performed again. A new systemic treatment line will start if there is polyprogression (more than 3 lesions at once), progression of more than 6 lesions over 12 months, intracranial progression, or lesions that cannot be treated locally.

The scientific question is whether local treatment of resistant metastases can prolong the effectiveness of ongoing systemic therapy, which is particularly beneficial if the treatment is well-tolerated. The primary objective is to measure the proportion of patients surviving without changing their systemic treatment line at 6 months after SBRT.

This trial is significant for patients as it explores a method to potentially extend the duration of effective and well-tolerated treatments, offering hope for better management of metastatic breast cancer.

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Key information

Conditions

OligoProgressive Metastatic Disease Breast Diseases Breast Neoplasms Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Jules Bordet Institute, Brussels, Belgium

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • ECOG performance status 0-2.
  • Histologically confirmed ER+/HER2- MBC.
  • History of polymetastatic disease. Patients with genuine oligometastatic disease and 1-3 oligoprogressive lesions are only allowed if ablative therapy of all metastases is deemed impossible.
  • Under 1st to 2nd systemic treatment line with hormonotherapy and/or CDK4/6 inhibitors for at least 6 months before progression.
  • Progressive disease at 1-3 extracranial sites.
  • Ability to treat all progressive lesions locally according to the treating radiation oncologist.

Exclusion criteria

  • Second malignancy if it is not in complete remission.
  • Previous local treatment for oligoprogression under the current systemic treatment line
  • Current progression in a lesion that has been treated with SBRT before and is not amendable for surgery or radiofrequency ablation (RFA).
  • Progressive or newly diagnosed brain metastases. Known brain metastases that have been nonprogressive for at least 6 months, are not an exclusion criterion.
  • Inability to continue the same ST line after local therapy (for example because of toxicity or patient refusal).
  • Pregnancy.
  • Inability to sign the informed consent.

Treatment and study plan

SBRT

Radiation

SBRT of all oligoprogressive metastases (or other local therapy if SBRT not advisable), followed by continuation of the same systemic therapy.

Primary outcomes

  1. NExt Systemic Treatment-Free Survival (NEST-FS)

    Time frame: At 6 months

Secondary outcomes

  1. Time to next line of systemic therapy (NEST)

    Time frame: 3 years

  2. Progression-free survival (PFS)

    Time frame: 3 years

  3. Modified Progression-free survival (mPFS)

    Time frame: 3 years

    Defined as the survival in the absence of any of the following : (1) polyprogression (progressive disease of more than 3 lesions at the same time), (2) progression of more than 6 lesions over a 12-month rolling period, (3) intracranial progression, (4) progressing lesion that cannot be treated locally, or (5) death.

  4. Chemotherapy-free survival

    Time frame: 3 years

  5. Progression-free survival after start of the subsequent line of systemic treatment (PFS2)

    Time frame: 3 year

  6. Patterns of metastatic progression

    Time frame: 3 years

    We defined four patterns of progression: stable disease, progression on untreated pre-existing lesions, progression on treated lesions, or development of new lesions. In case of progression, it will also be determined whether it is oligoprogression (progression of 3 lesions or less) or polyprogression (progression of more than 3 lesions).

  7. Overall survival (OS)

    Time frame: 3 years

  8. Acute and late physician-scored toxicity of the local intervention

    Time frame: 3 years

    Acute and late physician-scored toxicity of the local intervention (CTCAE 5.0, Early: within 90 days; late: 90 or more days after SBRT);

  9. Quality of life (QoL)

    Time frame: 3 years

    Evolution of QoL measured with the EORTC QLQ-C30

Other outcomes

  1. Correlation between (1) ctDNA burden at baseline and (2) ctDNA burden 10-12 weeks after SBRT versus the modified progression-free-survival (mPFS). NEST-FS in function of ESR1 status.

    Time frame: 3 years

Study contacts

Contact information is provided by the study sponsor or research team.

Robbe Van den Begin, MD PhD

CONTACT

[email protected]

+32 2 541 38 28

Sponsors and collaborators

Lead sponsor

Jules Bordet Institute

Other

Registry information

Official study title

The Oligopro-Breast Study: Stereotactic Radiotherapy for Oligoprogressive ER+/HER- Metastatic Breast Cancer, a Prospective Phase 2 Study

Important dates

Study start
2025
Primary completion
2028
Study completion
2030
First posted
Apr 13, 2025
Registry last updated
Feb 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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