A study looking at a new way to give melphalan chemotherapy for prostate cancer that can no longer be treated with hormone therapy (PR-2006-03)

Cancer type:

Prostate cancer

Status:

Results

Phase:

Phase 1

This study used stem cells to allow doctors to give melphalan (Alkeran) chemotherapy twice as often for prostate cancer.

Doctors often use hormone therapy to treat prostate cancer. This treatment usually works well for a few years. But the hormone therapy may stop working so well after a time. Doctors may then use other treatments, such as chemotherapy.

Doctors have used melphalan to treat prostate cancer, but it causes a drop in blood cells, limiting the chemotherapy dose men can have. In this study men had their own stem cells Open a glossary item through a drip after chemotherapy. This should have helped their blood cell counts to recover more quickly. So doctors should have been able to safely give the melphalan twice as often as before. They also wanted to see if hormone therapy would start working again after having melphalan. The aims of this study were to

Find out the highest dose of melphalan that men could have with a transplant of stem cells
See how well a higher dose of melphalan followed by stem cells worked for hormone resistant prostate cancer
Understand more about any side effects
Study prostate cancer cells from blood samples to understand what makes them respond to hormone therapy again

Summary of results

The study team found that melphalan followed by stem cell transplant did work for hormone resistant prostate cancer, but the side effects were quite bad.

This was a phase 1 study. It recruited 24 men. Everyone had melphalan followed by a stem cell transplant.

The first few men taking part had a low dose of melphalan. If they didn’t have any serious side effects, the next few men had a higher dose. And so on, until they found the highest dose they could give. This is called a dose escalation study.

To find out how well the treatment had worked the researchers looked at

Prostate specific antigen (PSA) levels in the blood
Bone scan and CT scan
Number of cancer cells that were in the blood – these are called circulating tumour cells (CTCs)

Of the 24 men recruited, the team were able to look at the results of 23.

PSA levels had fallen in 16 out of these 23 men. The average length of time it took for their PSA to start rising again was just under 3 months.

At 3 months the men had a bone scan and a CT scan. The bone scans showed that the cancer had got worse in 4 men. The team were able to look at the results of 11 CT scans. These showed that

The cancer had shrunk in 4 men – a partial response
The cancer had stayed the same in 7 men

The researchers found that those men who had low numbers of circulating tumour cells were free of their cancer for longer than those who had large numbers.

The worst side effect was a drop in the number of white blood cells causing an increased risk of infection. Unfortunately one man got a lung infection while his white blood cells were low and this caused his death.

Other side effects included

After completing their melphalan treatment, 20 men restarted hormone treatment when their PSA started to rise again. For 7 of these men, their PSA dropped by half or more.

The study team concluded that melphalan followed by stem cell transplant did work for men with hormone resistant prostate cancer but some side effects could be very harmful. They also said that CTCs could possibly be used to identify men who may benefit from having this treatment. They noted that the hormone resistant prostate cancer in many of these men responded when they restarted hormone treatment.

We have based this summary on information from the team who ran the trial. 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. We have not analysed the data ourselves.