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Recruiting Phase 2 NCT05301881

NCT05301881 COntinue the SaMe Systemic Therapy After Local Ablative Therapy for Oligo Progression in Metastatic Breast Cancer - the COSMO Study

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Clinical Trial Summary
NCT ID NCT05301881
Status Recruiting
Phase Phase 2
Sponsor The Netherlands Cancer Institute
Condition Breast Cancer Invasive
Study Type INTERVENTIONAL
Enrollment 118 participants
Start Date 2023-04-17
Primary Completion 2035-04-01

Eligibility & Interventions

Sex All sexes
Min Age 18 Years
Max Age N/A
Study Type INTERVENTIONAL
Interventions
SurgeryRadiotherapyRadiofrequent ablation

Eligibility Fast-Check

Enter your details for a quick preliminary check. This does not replace medical advice.

What to Expect as a Participant

You will actively receive the study intervention — which may be a drug, biologic, device, or procedure.

In Phase 2, researchers evaluate early signs of effectiveness. You may be randomized to receive the active treatment or a comparator. Monitoring continues closely.

This trial targets 118 participants in total. It began in 2023-04-17 with a primary completion date of 2035-04-01.

⚠ This information is for research awareness only. Always consult your physician before joining any clinical trial. Participation is voluntary and you may withdraw at any time.

Brief Summary

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 radiofrequency ablation (RFA).

Eligibility Criteria

Inclusion Criteria: * Histologically confirmed invasive breast cancer * Metastatic breast cancer * Oligoprogression defined as one or two distant metastatic lesions, limited to one organ, or the primary tumor or locoregional lymph nodes, increasing ≥20% in size and be larger than 15 mm or if metabolic activity increases (with 20% in SUVmax) on FDG-PET-CT. * 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. * The radiological imaging that shows progression must be performed within 70days 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 * Oligo-progression has to be confirmed with a FDG-PET-CT-scan 5-7 weeks after the initial scan that showed oligoprogression. * Lesion(s) must be amenable to resection, radiotherapy or radiofrequency ablation with the intent of local obliteration * 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

Contact & Investigator

Central Contact

G Sonke, MD

✉ g.sonke@nki.nl

📞 +31-20-512

Principal Investigator

G Sonke

PRINCIPAL INVESTIGATOR

The Netherlands Cancer Institute

Frequently Asked Questions

Who can join the NCT05301881 clinical trial?

This trial is open to participants of all sexes, aged 18 Years or older, studying Breast Cancer Invasive. Full inclusion and exclusion criteria are listed in the Eligibility Criteria section. Always confirm your eligibility with the research team before applying.

What phase is the NCT05301881 trial and what does that mean for participants?

Phase 2 trials evaluate whether the treatment shows signs of effectiveness while continuing to monitor safety. More participants are enrolled than in Phase 1 to help refine the treatment protocol.

Is NCT05301881 currently recruiting?

Yes, NCT05301881 is actively recruiting participants. Contact the research team at g.sonke@nki.nl for enrollment information.

Where is the NCT05301881 trial being conducted?

This trial is being conducted at Alkmaar, Netherlands, Amsterdam, Netherlands, Arnhem, Netherlands, Deventer, Netherlands and 3 additional locations.

Who is sponsoring the NCT05301881 clinical trial?

NCT05301881 is sponsored by The Netherlands Cancer Institute. The principal investigator is G Sonke at The Netherlands Cancer Institute. The trial plans to enroll 118 participants.

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ClinicalMetric — Independent clinical trial intelligence platform. Not affiliated with NIH, ClinicalTrials.gov, the U.S. FDA, or any pharmaceutical company, hospital, or clinical research organization. Trial data is sourced from ClinicalTrials.gov for informational purposes only and does not constitute medical advice. Do not make any treatment, enrollment, or health decisions based solely on information found here — always consult a qualified healthcare professional. Full Disclaimer  ·  Last Reviewed: April 2026  ·  Data Methodology