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Soft Tissue Sarcoma (STS)Phase 2PROSARC-2NCT07173972

Dose-escalated, Hypofractionated, Definitive Proton Radiotherapy for Patients With Inoperable Soft Tissue Sarcoma.

A Phase 2 study testing Definitive radiotherapy in people with Soft Tissue Sarcoma (STS) and Soft Tissue Sarcoma Adult, run by Oslo University Hospital at 2 sites in Norway.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

The purpose of the study is to study if dose escalated proton radiotherapy can improve local controll for patients with inoperable soft tissue sarcomas. The standard treatment is photon-based radiation. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Definitive radiotherapy
Type of treatment
Surgery or procedure
Could I receive a placebo?
No, everyone receives an active treatment
How many people
40 participants
Where
2 sitesNorway
Study dates
26 Jan 2026to 1 Nov 2035
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • ≥ 18 years of age at the time of informed consent.
  • Histological diagnosis of soft tissue sarcoma including gastrointestinal stromal tumor (GIST).
  • Measurable disease according to RECIST v1.1.
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2
  • For patients with metastatic disease a life-expectancy greater than 2 years should be expected.
  • Before patient registration, written informed consent must be given according to national and local regulations.
  • Ability to fill in patient questionnaires and comply with study procedures, including travelling to Bergen or Oslo for Proton Beam radiotherapy.

Who cannot join

  • Patients with a prior or concurrent malignant disease whose natural history or treatment have the potential to interfere with the safety or efficacy assessment of this clinical trial are not eligible. Patients with a history of breast cancer, requiring continued hormonal treatment (e.g. anti-estrogen or an aromatase inhibitor) may be included. Patients with a history of prostate cancer, requiring continued support with luteinizing hormone releasing hormone (LHRH) agonists, with or without androgens, may be included.
  • Previous radiotherapy to the tumor site.
  • Patients with pacemakers and/or implanted defibrillators.
  • Patients not able to give an informed consent or comply with study regulations as deemed by study investigator.
  • Administration of systemic cancer therapy (i.e. chemotherapy, targeted therapy or immune therapy) within 14 days prior to the first fraction of radiotherapy.

Trial locations and contacts

2 sites in 1 country. Contact the study team or a site near you to ask about taking part.

Martine Karlsen Karlsen Ødegaard, Cancer Nurse contact

+47 99562019

martineko@ous-hf.no

Norway2 sites, 2 recruiting

  • Haukeland University Hospital

    Bergen

    Dorota Goplen, MD, PhD, +4755975000, dorota.katarzyna.pazdyk.goplen@helse-bergen.no

    Not yet recruiting

  • Oslo University Hospital

    Oslo

    Ivar Hompland, MD, PhD, +4791698933, ivahom@ous-hf.no

    Recruiting

Other trials in Norway

About this study

Official title: PROSARC-2. Dose-escalated, Hypofractionated, Definitive Proton Radiotherapy for Patients With Inoperable Soft Tissue Sarcoma. A Single-arm, Multicenter, Phase II Clinical Trial.

The purpose of the study is to study if dose escalated proton radiotherapy can improve local controll for patients with inoperable soft tissue sarcomas. The standard treatment is photon-based radiation. By using proton radiotherapy instead, the hypothesis is that the dose can be increased to enhance treatment effectiveness without increasing side effects.

The planned radiation dose is 56 Gy in 16 fractions (treatments) over 4 weeks (4 fractions per week), with a maximum dose escalation centrally in the tumor up to 80 Gy (5 Gy per fraction).

Read more

At the same time, the study will investigate biomarkers that can predict treatment response, including changes in the tumor's genetic material (DNA), measurements of various molecules in the bloodstream, and the tumor's appearance on MRI scans.

The primary endpoint is local control after 2 years, meaning that the treated tumor has not grown during this period. Secondary endpoints include overall survival, progression-free survival, radiological response rates, side effects, and quality of life.

The study will be conducted in Norway, with a planned inclusion of 40 patients.

Read the detailed description

The objective of the PROSARC-2 trial is to investigate whether dose-escalated hypofractionated, definitive, proton beam therapy (PBT) can result in better local control in soft tissue sarcoma (STS). PROSARC-2 is a single arm, open-label, multicenter phase II clinical trial initiated at the Department of Oncology, Oslo University Hospital (OUS). The main inclusion criterion is patients with inoperable soft tissue sarcoma. The primary endpoint is 2-year local progression-free survival (LPFS). We expect to include 40 patients over three years and all patients will be followed for up to five years. All the sarcoma centers in Norway participate in the study: OUS; Haukeland University Hospital (HUH); St Olavs Hospital (SOH) and University Hospital of North-Norway (UNN). The indication for definitive radiotherapy (RT) will be decided in the sarcoma multidisciplinary (MDT) meeting at each center. A weekly/biweekly national sarcoma RT meeting will make the decision whether hypofractionated, dose-escalated PBT will be feasible after a careful clinical evaluation. For included patients PBT will be given at OUS and HUH. The prescribed dose is 56 Gray (Gy) in 16 fractions over 4 weeks (14 Gy per week) with a maximum dose-escalation to the tumor core of 80 Gy (5 Gy per fraction).

The PROSARC-2 trial includes translational radiomic research, where we aim to elucidate underlying mechanisms related to RT effect. To facilitate future biomarker studies for personalized therapy we will collect excess tumor tissue, whole blood, plasma and serum.

Being tested
Definitive radiotherapy
Keywords
soft tissue sarcoma, proton radiotherapy, inoperable soft tissue sarcoma
Medical subject headings
Sarcoma, Sarcoma, Synovial, Histiocytoma, Malignant Fibrous, Dermatofibrosarcoma, Leiomyosarcoma, Liposarcoma

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Definitive radiotherapyRadiation

    The prescribed dose is 56 Gray (Gy) in 16 fractions over 4 weeks (14 Gy per week) with a maximum dose-escalation to the tumor core of 80 Gy (5 Gy per fraction).

Study groups in NCT07173972
Study groupRoleWhat they receive
Inoperable soft tissue sarcomaExperimentalNot described
Receives: Radiation: Definitive radiotherapy

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Local progression-free survival

    Local progression-free survival is measured from the date of start of study treatment until date of local progression of the tumor that has undergone proton beam radiotherapy evaluated using RECIST v1.1 or date of death of any cause, whichever occurs first.

    Measured: 2 Year

Secondary outcomes (5)

  1. Progression-free survival

    Progression-free survival is measured from the date of start of study treatment until date of progressive disease (local and/or distant) as evaluated using RECIST v1.1 or date of death of any cause, whichever occurs first.

    Measured: Up to five years after radiation therapy

  2. Overall survival

    Overall survival is measured from the date of start of study treatment until date of death of any cause.

    Measured: Up to five years after radiation therapy.

  3. Overall response rate, defined as partial or complete response using RECIST v1.1

    Radiological response will be assessed using MRI and/or CT of the primary tumor.

    Measured: Up to five years after radiation therapy.

  4. Health-related quality of life

    Change from baseline in EORTC QLQ-C30 scores.

    Measured: Up to five years after radiation therapy.

  5. To assess acute and late toxicity

    Treatment-related toxicity during treatment and follow-up using CTCAE v5.0.

    Measured: Up to five years after radiation therapy.

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted15 Sep 2025
  2. Study start26 Jan 2026
  3. Primary completion26 Jan 2029 (estimated)
  4. Study completion1 Nov 2035 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
40 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07173972
Sponsor's protocol ID
916024
Acronym
PROSARC-2
Status last verified
Jan 2026
First submitted
8 Sep 2025
Last updated
28 Jan 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Definitive radiotherapy in people with Soft Tissue Sarcoma (STS) and Soft Tissue Sarcoma Adult, run by Oslo University Hospital at 2 sites in Norway.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 28 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in Norway. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Martine Karlsen Karlsen Ødegaard, Cancer Nurse (+47 99562019, martineko@ous-hf.no), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Local progression-free survival (time frame: 2 Year). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07173972.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Jan 2026.

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