A study looking at a vaccination called TroVax in people with bowel cancer that has spread and cannot be removed with surgery (TaCTiCC)

Cancer type:

Bowel (colorectal) cancer

Secondary cancers

Status:

Results

Phase:

Pilot

This study looked at how a vaccine called TroVax affects the immune system in people who have bowel cancer that has spread to another part of the body.

More about this trial

Doctors can treat bowel cancer that has spread (advanced bowel cancer) with chemotherapy. But researchers are looking for ways to improve current standard treatments Open a glossary item .

If you have cancer, your immune system tries to attack and kill the cancer cells. Treatments such as TroVax may help the immune system to do this. But other cells in your body can stop your immune system attacking the cancer cells.

Researchers wanted to find out if a chemotherapy drug called cyclophosphamide can help get rid of cells that stop the immune system attacking cancer cells.

The main aim of this study was to see if there is a difference in how well your immune system responds to bowel cancer (the immune response Open a glossary item ) when you have TroVax or cyclophosphamide, or both.

Summary of results

This study showed that both cyclophosphamide and TroVax triggered the immune system into action in patients with advanced bowel cancer.

Results

The research team looked at the results of 52 people who took part. They all had bowel cancer that had spread to another part of the body, and had already had chemotherapy. Of those who took part:

8 didn’t have treatment as part of the study (group 1)
9 had cyclophosphamide tablets for 2 weeks (group 2)
17 had TroVax injections over 4 months (group 3)
18 had cyclophosphamide tablets followed by TroVax injections (group 4)

The research team measured the levels of various parts of the immune system in everyone taking part, to see if there were any changes.

The first were T cells, which help the immune system to kill cancer cells. The research team found that the number at least doubled in:

10 out of 17 patients (59%) who hadn’t had TroVax (groups 1 and 2)
20 out of 35 patients (57%) who’d had Trovax (groups 3 and 4)

The second were specific proteins made by B cells, which also help the body kill cancer cells. They found the number had at least doubled in:

15 out of 17 people (88%) who’d had TroVax alone (group 3)
13 out of 18 people (72%) who’d had cyclophosphamide and TroVax (group 4)

The third were regulatory T cells, or Tregs. These cells stop the immune system from killing cancer cells. So, by reducing the number of Tregs the immune system can kill cancer cells.

The research team found that people who’d had either cyclophosphamide or TroVax had a lower number of Tregs. But they found that having both treatments together didn’t work better than either of the treatments on their own.

When the research team looked at how well the treatment worked, they found the cancer stopped growing for longer in those whose immune system had responded to treatment. But it’s hard to draw firm conclusions because this was a small study.

Side effects

The people taking part didn’t have many side effects from either the cyclophosphamide or the TroVax, and they were mostly mild and didn’t last long. The most common side effects were feeling or being sick, and soreness at the injection site.

Conclusion

The research team concluded that both cyclophosphamide and TroVax were safe to use, and that either could be a useful treatment for bowel cancer that has spread. They suggest that larger trials are done to find out more about how well these treatments work, perhaps looking at other treatments alongside TroVax.

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item

) 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.