A study looking at irosustat for early breast cancer (IPET)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Breast cancer




Phase 2

This study is looking at a new drug called irosustat to treat early breast cancer Open a glossary item. It is for post menopausal Open a glossary item women who have oestrogen receptor positive Open a glossary item (ER positive) breast cancer.

Doctors often treat early breast cancer with surgery. They may suggest chemotherapy before surgery to shrink the cancer. This is called neo adjuvant chemotherapy.

Most breast cancers in post menopausal women need the hormone oestrogen Open a glossary item to grow. There are 2 pathways in the body that make oestrogen.

Irosustat is a type of hormone therapy that blocks one of these pathways.

In this study you have irosustat in the 2 weeks while you are waiting to have your planned treatment. During this time you will have 2 PET-CT scans. The researchers will use these scans to find out if irosustat can slow or stop the growth of the cancer.

The aim of this study is to use PET-CT scans to find out if irosustat can stop or slow the growth of early ER positive breast cancer.  

Who can enter

You may be able to enter this trial if

You cannot enter this trial if

  • You have cancer that has spread into the surrounding tissue (locally advanced breast cancer) or to another part of your body (secondary breast cancer)
  • You have inflammatory breast cancer
  • You have cancer that has spread throughout your breast
  • You have had another cancer in the past 5 years apart from successfully treated non melanoma skin cancer or carcinoma in situ of the cervix
  • You have had medications or supplements containing oestrogen, such as hormone replacement therapy Open a glossary item (HRT), vaginal oestrogen or phyto oestrogens Open a glossary item, in the month before agreeing to take part in this study
  • You have ever had an oestrogen implant Open a glossary item
  • You are taking any medication or supplements that affect the CYP2A or CYP3A enzymes,or that affect how irosustat works in the body
  • You have a serious heart problem
  • You have an infection that is causing problems
  • You have any other medical condition that could affect you taking part in this study
  • There is a reason you can’t have a PET-CT scan, such as not being able to lie flat

Trial design

This is a phase 2 trial. It will recruit 24 women. This study takes place while you are waiting to have your planned treatment.

Irosustat is a tablet. You take it daily for 2 weeks. You have a PET-CT scan before and after treatment.

You shouldn’t eat for 6 hours before your scan. You are allowed to drink water. You have an injection into a vein of a small amount of a radioactive drug (tracer). The scan takes about an hour.

If you agree to take part in this study the researchers will ask you for a sample of tissue after you have stopped taking irosustat. They will take it when you have your surgery. If you are to have additional treatment to shrink your cancer before surgery, they will do a needle biopsy. You don’t have to agree to this if you don’t want to. You can still take part in the study.

Hospital visits

You see the doctor to have some tests before taking part in this study. These tests include

  • Physical examination
  • Blood tests
  • Heart trace (ECG Open a glossary item)

You have a PET-CT scan before starting the treatment. During treatment you see the doctor each week for a physical examination and blood tests. In the second week of treatment, you have another PET-CT scan and a heart trace.

A month after treatment you see the doctor for the same tests, apart from the PET-CT scan.

Side effects

The most common side effects of irosustat are

The PET-CT scan is a safe test. The amount of radioactive drug is very small and shouldn’t cause any side effects. You may feel a little dizzy after the scan but this should soon go away.

Your doctor will talk to you about possible side effects before you agree to take part in this study.

We have information about PET-CT scans in our cancer tests section.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Dr Palmieri

Supported by

Biomedical Research Centre
Imperial Clinical Trials Unit – Cancer (ICTU-Ca)
Imperial College Healthcare NHS Trust

Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:

Oracle 8041

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Harriet wanted to try new treatments

Picture of Harriet

“I was keen to go on a clinical trial. I wanted to try new cancer treatments and hopefully help future generations.”

Last reviewed:

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