COntinue the SaMe Systemic Therapy After Local Ablative Therapy for Oligo Progression in Metastatic Breast Cancer - the COSMO Study (COSMO)

September 8, 2026 updated by: The Netherlands Cancer Institute
Patients with oligoprogression of metastatic breast cancer during palliative treatment that is amenable to local therapy will be included. The local ablative therapy (LAT) may consist of stereotactic ablative radiotherapy (SABR), also known as stereotactic body radiation therapy, surgery or percutaneous ablation.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
56

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: G Sonke, MD
  • Phone Number: 9111 +31-20-512
  • Email: g.sonke@nki.nl

Study Contact Backup

Study Locations

  • Netherlands
      • Alkmaar, Netherlands
        • Recruiting
        • Noordwest Ziekenhuisgroep
        • Contact:
          • S Vrijaldenhoven, MD
        • Principal Investigator:
          • S Vrijaldenhoven, MD
      • Amsterdam, Netherlands
        • Recruiting
        • Antoni van Leeuwenhoek
        • Contact:
        • Principal Investigator:
          • G Sonke, MD
        • Contact:
      • Arnhem, Netherlands
        • Recruiting
        • Rijnstate
        • Contact:
        • Principal Investigator:
          • K J Beelen, MD
      • Deventer, Netherlands
        • Recruiting
        • Deventer Ziekenhuis
        • Principal Investigator:
          • A Imholz, MD
        • Contact:
          • LW. Kessels, MD
      • Goes, Netherlands
        • Recruiting
        • ADRZ
        • Contact:
        • Principal Investigator:
          • E van Vliet, MD
      • Groningen, Netherlands
        • Recruiting
        • Martini Ziekenhuis
        • Contact:
          • A van der Velden, MD
        • Principal Investigator:
          • A van der Velden, MD
      • Utrecht, Netherlands
        • Recruiting
        • Antonius ziekenhuis
        • Contact:
          • M Agterof, MD
        • Principal Investigator:
          • M Agterof, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Histologically confirmed invasive breast cancer
  • Metastatic breast cancer
  • o Oligoprogression is defined as an increase of ≥20% in size or, in case of FDG-PET-CT, metabolic activity (≥20% in SUVmax) involving a maximum of two lesions. These lesions may consist of: 1 or 2 distant metastatic lesions limited to 1 organ, the primary tumor or locoregional lymph nodes.
  • Systemic treatment can be either endocrine, targeted, chemotherapy or immune-checkpoint blockade
  • Patients should be on systemic therapy for at least six months. Status should be stable disease or partial or complete response for at least 6 months.
  • Oligoprogression has to be detected with radiological imaging comparing the lesion on the same type of imaging modality as has been used at the start of systemic therapy.
  • Lesion(s) must be amenable to resection, radiotherapy or percutaneous ablation with the intent of local obliteration.
  • The radiological imaging that shows progression must be performed within 70 days prior to LAT.
  • Bone metastases are classified as progressive if the lytic component of the lesion increases by ≥20% or the FDG-uptake increases by ≥20% on FDG-PET-CT
  • Lymph nodes should be larger than 15 mm upon first detection of oligoprogression to be classified as progressive.
  • Oligo-progression has to be confirmed with a FDG-PET-CT-scan 5-7 weeks after the initial scan that showed oligoprogression.
  • Age ≥18
  • World Health Organization (WHO) Performance Status 0 or 1
  • Signed written informed consent before patient registration according to ICH/GCP, and national/local regulations

Exclusion Criteria:

  • Having received more than two lines of systemic therapy for MBC If a treatment regimen has been de-escalated without adding other therapies, this is seen as one line of therapy. For example: Pertuzumab/trastuzumab+docetaxel followed by pertuzumab/trastuzumab will be viewed as one line of systemic therapy.
  • Other malignancy except carcinoma in situ and basal-cell and squamous cell carcinoma of the skin, unless the other malignancy was treated ≥5 years ago with curative intent without the use of chemotherapy or radiation therapy
  • Current pregnancy or breastfeeding. Women of childbearing potential must use adequate contraceptive protection
  • Presence of any medical condition that would place the patient at unusual risk, up to the discretion of the clinician
  • Presence of any psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Other: Surgery, radiotherapy or radiofrequent ablation
The oligoprogresive lesion(s) will be treated with Surgery, radiotherapy or percutaneous ablation depending on the location of the lesion. treatment will be standard of care and will be decided by the treating team of the patient.
Procedure: Surgery
resection of the oligometastatic lesion(s)
Radiation: Radiotherapy
radiation of the oligometastatic lesion(s)
Other: Radiofrequent ablation
radiofrequent ablation of the oligometastatic lesion(s)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of patients free of progression at 6 months
Time Frame: At 6 months
progression-free survival at 6 months (PFS-6)
At 6 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Number of patients free of progression at 6 months per histoligical subtype
Time Frame: At 6 months
PFS-6 for breast cancer subtypes: ER+/HER2- vs. HER2+ vs. TN
At 6 months
Number of patients free of progression at 6 months per breast cancer subtype
Time Frame: At 6 months

PFS-6, stratified by breast cancer subtype

- localization of progressive lesion
At 6 months
Number of patients free of progression at 6 months per localization of progressive lesion
Time Frame: At 6 months
PFS at 6 months separately for localization of progressive lesion: locoregional vs. cranial vs. visceral vs. bone
At 6 months
Overall Surival (OS)
Time Frame: Up to 120 months
Evaluation of overall survival measured from baseline till death due to any cause
Up to 120 months
Time to next line of treatment
Time Frame: Up to 120 months
Time to next line of systemic therapy meeasured from baseline
Up to 120 months
Number of patients who develop "visceral crisis"
Time Frame: Up to 120 months
number of patients who develop "visceral crisis"
Up to 120 months
Number of patients who develop complications after local ablative treatment
Time Frame: Up to 120 months
Assess the number of patients who develop complications after local ablative treatment
Up to 120 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
The Netherlands Cancer Institute

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Maarten van de Weijden Foundation

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: G Sonke, The Netherlands Cancer Institute

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 17, 2023

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 1, 2035

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2040

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 21, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 21, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 31, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 8, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • M21CSM

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

to be determined

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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