RecruitingPhase IIInterventional

A study to explore the effect of immunotherapy drug, tebentafusp, on patients with clear cell sarcoma (ultra-rare, aggressive type of soft tissue sarcoma that primarily affects young adults)

This study explores a new treatment for clear cell sarcoma, a very rare and aggressive cancer that mainly affects young adults and has few treatment options. Researchers are testing a drug called tebentafusp, which is already approved for a type of skin cancer called melanoma. Previous studies suggest it might also work for clear cell sarcoma. The main goal is to find out if tebentafusp can help patients with this cancer and how long any benefits might last. Researchers will also collect blood and tissue samples to understand how the drug works. Participants will have regular clinic visits for checks, blood tests, and scans. The study is run by the Royal Marsden NHS Foundation Trust and funded by the Sarcoma Alliance for Research through Collaboration.

At a glance

Status

Recruiting

Phase

Phase II

Sponsor

Sarcoma Alliance for Research through Collaboration

Enrolment target

Start

30 Jan 2026

Estimated completion

31 Dec 2032

Clear cell sarcoma

What is this study about?

This study is looking into a new way to treat clear cell sarcoma, which is a very rare and aggressive type of cancer that affects the soft tissues in the body. It often affects young adults and unfortunately, there aren't many effective treatments available right now. The researchers want to test a medicine called tebentafusp. This drug is already used successfully for a type of skin cancer called melanoma, and early research suggests it might also be helpful for clear cell sarcoma.

The main aim of this study is to see if tebentafusp can work for clear cell sarcoma patients. They’ll also be checking how long the treatment's effects last if it does work. To understand more about the drug and how it affects the body, the research team will collect blood and tissue samples from participants. This will help them learn why the drug might help some patients and not others. Participants will have regular appointments at the clinic for various checks, including blood tests and scans like CT or MRI.

Patients on this study will continue their treatment for as long as it's helping them, or until they choose to stop or experience side effects that are too difficult to manage. Even if the cancer shows some changes, patients who are benefiting can sometimes continue on the study. After the treatment period, patients will have follow-up checks every three months to monitor their health.

Key takeaways

The study tests a drug called tebentafusp for a rare cancer, clear cell sarcoma.
Tebentafusp is already used for melanoma, but its effect on clear cell sarcoma is new.
Participation involves regular clinic visits, blood tests, scans, and possibly biopsies.
Treatment continues as long as it's beneficial, with follow-up after stopping.
Common side effects may include fever, skin reactions, and changes in liver tests.
The study starts in October 2025 and runs until December 2032.

Who may be eligible?

To be able to join this study, you need to be at least 18 years old and have clear cell sarcoma that has spread or can't be removed by surgery. An important part of joining is having a specific genetic marker called HLA-A*02:01, which is found through a screening test. You also need to be generally well enough to take part in the study, which doctors will check.

There are also some reasons why you might not be able to join. For example, if you've had a very bad allergic reaction to similar medicines in the past, or if you have certain serious heart problems. The doctors will also check your organ functions, like your liver and kidney, to make sure they are working well enough for you to safely receive the treatment.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Do you have clear cell sarcoma that has spread or can't be removed?
Have you been tested for the HLA-A*02:01 marker and are positive?
Are you generally well enough to take part (your doctor will check this)?
Do you have good organ function (like liver and kidneys)?
Have you consented (given permission) to participate?

Answer every question to see your result.

What does participation involve?

If you join the main part of the study, you'll receive the tebentafusp medicine weekly through a drip (infusion) for a three-week cycle. The dose will start low and increase during the first cycle. You'll have regular clinic visits for blood tests and other health checks. Scans like CT or MRI will be done regularly (every 6 or 9 weeks) to see how the treatment is working. Some patients will also be asked to have biopsies (small tissue samples) taken at the start of the study and after 6 weeks, if it's safe to do so.

You typically continue treatment until your cancer gets worse, or if you decide to stop, or if the side effects become too strong. However, if the treatment is still helping you, you might be able to continue even if your cancer changes slightly. For those who don't have the specific genetic marker needed for tebentafusp, you might be offered a different treatment chosen by your doctor but still have similar regular check-ups and scans as part of a separate group. After treatment finishes, all participants will have follow-up checks every three months.

Potential risks and benefits

There’s no guarantee that participating in this study will directly benefit you, but researchers hope that some patients may experience positive effects on their health and their cancer. Tebentafusp is a medicine that has already been approved and is used by doctors for other conditions, so its main side effects are known. Common side effects can include fever, skin reactions (like rashes), and changes in liver enzyme levels, which doctors will monitor closely. You have the right to withdraw from the study at any time, for any reason, without it affecting your usual medical care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

The Royal Marsden NHS Foundation Trust
City only
London, England

Common questions

What is clear cell sarcoma?

It's a very rare and aggressive type of cancer that affects the body's soft tissues, often in young adults, and there are currently limited treatment options.

What is tebentafusp?

It's a medicine that is already approved for a type of skin cancer called melanoma. This study is testing if it can also help patients with clear cell sarcoma.

What is HLA-A*02:01?

It's a specific marker (a type of protein) found in your body. You need to have this marker to receive the tebentafusp treatment in this study.

How long will the study last for me?

You will receive treatment for as long as it's helping you, or until you choose to stop. After treatment, there will be follow-up checks every three months.

Will my family or friends know I'm in the study?

All your personal information will be kept private and confidential. Your participation will only be shared with those involved in your medical care, unless you give permission otherwise.

How to find out more

Olga Peycheva

olga.peycheva@solutionsop.co.uk +44 7484 105719 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.