A trial of cabozantinib for gastro intestinal stromal tumour (CaboGIST; EORTC 1317)

The research team found that cabozantinib could be a useful treatment for GIST that had spread.

Trial design
This trial was for people with gastro intestinal stromal tumour (GIST) that had spread. They’d already had treatment with imatinib and sunitinib, but their GIST had continued to grow.

Everyone taking part had cabozantinib tablets once a day. They took it for as long as it was working and the side effects weren’t too bad.

Results
A total of 50 people joined this trial. They all had GIST that had spread.

At 12 weeks after starting treatment, the research team looked at how many people’s GIST had not grown any more. They found it was 30 out of 50 people (60%). 

They also looked at how well the treatment worked overall. They were able to assess this for 49 out of the 50 people who took part. They found that the cancer:

• got a bit smaller in 7 people (14%)
• stayed the same in 34 people (68%)
• continued to grow in 8 people (16%)

CABOGIST trial bar chart showing how treatment affected GIST

These results are a bit better than you would expect with other treatments available for GIST that has spread.

Side effects
Nearly everyone taking part had at least 1 side effect, but some of these were mild. 

Non serious side effects
The most common non serious side effects were:

• 38 people (76%) had diarrhoea
• 30 people (60%) had sore skin on their hands and feet (palmar plantar syndrome)
• 25 people (50%) had extreme tiredness (fatigue)
• 21 people (42%) had increased blood pressure
• 20 people (40%) had weight loss
• 15 people (30%) had a sore mouth (mucositis)

CABOGIST trial bar chart showing the most common non serious side effects

Some people had the same side effects, but they were worse. This included 13 people (26%) who had more severe diarrhoea. And 4 people (8%) who had more severe palmar plantar syndrome.

Serious side effects
Researchers can class a side effect as serious for a number of reasons, including if:

• the person has to go to hospital because of it
• it is particularly important for the specific treatment in the trial

A total of 15 people in this trial had a serious side effect.

The most common serious side effects were:

• 3 people (6%) had diarrhoea
• 2 people (4%) had a change in heart rhythm called atrioventricular block
• 2 people (4%) developed a small tube between the bowel and the skin (an anal fistula)

CABOGIST trial bar chart showing the most common serious side effects

Measuring how well treatment works
In 2022, the research team looked at a new way to measure how well treatment had worked. They used a system that looked at the density of the cancer as well as the size. This is called the Choi criteria. 

They also used the RECIST criteria, which was the standard system used at the time. Someone at each hospital looked at the scans of the people taking part there (local RECIST). And someone at a central hospital looked at all the scans (central RECIST).

The team compared:

• the Choi criteria
• local RECIST
• central RECIST

They looked at 43 people who took part in the CaboGIST trial.

The found that the Choi criteria and the central RECIST both classed:

• more people’s GIST as having got smaller or stayed the same, and
• fewer people’s GIST as having got worse

This is compared to local RECIST.

Conclusion
The research team concluded that cabozantinib could be a useful treatment for GIST. This is for people whose GIST has continued to grow despite other treatment. They suggest more trials are done.

They also concluded that it’s important to include the density of GIST when looking to see how well treatment has worked.

Other trials of cabozantinib in the future may show different results.

More detailed information
There is more information about this research in the references below. 

Please note, these articles are not in plain English. They have been written for health care professionals and researchers.

Activity and safety of the multi-target tyrosine kinase inhibitor cabozantinib in patients with metastatic gastrointestinal stromal tumour after treatment with imatinib and sunitinib: European Organisation for Research and Treatment of Cancer phase II trial 1317 'CaboGIST'
P Schöffski and others
European Journal of Cancer, 2020. Volume 134, pages 62-74.

Exploratory analysis of tumor imaging in a Phase 2 trial with cabozantinib in gastrointestinal stromal tumor: lessons learned from study EORTC STBSG 1317 ‘CaboGIST’
A Kyriazoglou and others
Acta Oncologica, 2022. Volume 61, issue 6, pages 663–668

Future plans
At the time of writing this summary there were no other planned trials looking at cabozantinib for GIST.

Where this information comes from
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.